tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph
Subsystems (16)
Masami Hiramatsu (Google)
maintainerv17 cover tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph
Hi,
Here is the 17th version of the series to re-implement the fprobe on function-graph tracer. The previous version is;
https://lore.kernel.org/all/172895571278.107311.14000164546881236558.stgit@devnote2/
This version rebased on ftrace/for-next branch on linux-trace tree and drop first 2 patches and fix s390 implementations according to Heiko's review (Thanks!).
Overview
--------
This series rewrites the fprobe on this function-graph. The purposes of this change are;
1) Remove dependency of the rethook from fprobe so that we can reduce the return hook code and shadow stack.
2) Make 'ftrace_regs' the common trace interface for the function boundary.
1) Currently we have 2(or 3) different function return hook codes, the function-graph tracer and rethook (and legacy kretprobe). But since this is redundant and needs double maintenance cost, I would like to unify those. From the user's viewpoint, function- graph tracer is very useful to grasp the execution path. For this purpose, it is hard to use the rethook in the function-graph tracer, but the opposite is possible. (Strictly speaking, kretprobe can not use it because it requires 'pt_regs' for historical reasons.)
2) Now the fprobe provides the 'pt_regs' for its handler, but that is wrong for the function entry and exit. Moreover, depending on the architecture, there is no way to accurately reproduce 'pt_regs' outside of interrupt or exception handlers. This means fprobe should not use 'pt_regs' because it does not use such exceptions. (Conversely, kprobe should use 'pt_regs' because it is an abstract interface of the software breakpoint exception.)
This series changes fprobe to use function-graph tracer for tracing function entry and exit, instead of mixture of ftrace and rethook. Unlike the rethook which is a per-task list of system-wide allocated nodes, the function graph's ret_stack is a per-task shadow stack. Thus it does not need to set 'nr_maxactive' (which is the number of pre-allocated nodes).
Also the handlers will get the 'ftrace_regs' instead of 'pt_regs'. Since eBPF mulit_kprobe/multi_kretprobe events still use 'pt_regs' as their register interface, this changes it to convert 'ftrace_regs' to 'pt_regs'. Of course this conversion makes an incomplete 'pt_regs', so users must access only registers for function parameters or return value.
Design
------
Instead of using ftrace's function entry hook directly, the new fprobe is built on top of the function-graph's entry and return callbacks with 'ftrace_regs'.
Since the fprobe requires access to 'ftrace_regs', the architecture must support CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS and CONFIG_HAVE_FTRACE_GRAPH_FUNC, which enables to call function-graph entry callback with 'ftrace_regs', and also CONFIG_HAVE_FUNCTION_GRAPH_FREGS, which passes the ftrace_regs to return_to_handler.
All fprobes share a single function-graph ops (means shares a common ftrace filter) similar to the kprobe-on-ftrace. This needs another layer to find corresponding fprobe in the common function-graph callbacks, but has much better scalability, since the number of registered function-graph ops is limited.
In the entry callback, the fprobe runs its entry_handler and saves the address of 'fprobe' on the function-graph's shadow stack as data. The return callback decodes the data to get the 'fprobe' address, and runs the exit_handler.
The fprobe introduces two hash-tables, one is for entry callback which searches fprobes related to the given function address passed by entry callback. The other is for a return callback which checks if the given 'fprobe' data structure pointer is still valid. Note that it is possible to unregister fprobe before the return callback runs. Thus the address validation must be done before using it in the return callback.
Download
--------
This series can be applied against the ftrace/for-next branch in linux-trace tree.
This series can also be found below branch.
https://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git/log/?h=topic/fprobe-on-fgraph
Thank you,
---
Masami Hiramatsu (Google) (16):
function_graph: Pass ftrace_regs to entryfunc
function_graph: Replace fgraph_ret_regs with ftrace_regs
function_graph: Pass ftrace_regs to retfunc
fprobe: Use ftrace_regs in fprobe entry handler
fprobe: Use ftrace_regs in fprobe exit handler
tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs
tracing: Add ftrace_fill_perf_regs() for perf event tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS
bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled
ftrace: Add CONFIG_HAVE_FTRACE_GRAPH_FUNC
fprobe: Rewrite fprobe on function-graph tracer tracing/fprobe: Remove nr_maxactive from fprobe
selftests: ftrace: Remove obsolate maxactive syntax check selftests/ftrace: Add a test case for repeating register/unregister fprobe
Documentation: probes: Update fprobe on function-graph tracer
bpf: Add get_entry_ip() for arm64
Documentation/trace/fprobe.rst | 42 + arch/arm64/Kconfig | 2 arch/arm64/include/asm/ftrace.h | 47 + arch/arm64/kernel/asm-offsets.c | 12 arch/arm64/kernel/entry-ftrace.S | 32 + arch/arm64/kernel/ftrace.c | 20 + arch/loongarch/Kconfig | 4 arch/loongarch/include/asm/ftrace.h | 32 - arch/loongarch/kernel/asm-offsets.c | 12 arch/loongarch/kernel/ftrace_dyn.c | 10 arch/loongarch/kernel/mcount.S | 17 - arch/loongarch/kernel/mcount_dyn.S | 14 arch/powerpc/Kconfig | 1 arch/powerpc/include/asm/ftrace.h | 13 arch/powerpc/kernel/trace/ftrace.c | 2 arch/powerpc/kernel/trace/ftrace_64_pg.c | 10 arch/riscv/Kconfig | 3 arch/riscv/include/asm/ftrace.h | 45 + arch/riscv/kernel/ftrace.c | 17 + arch/riscv/kernel/mcount.S | 24 - arch/s390/Kconfig | 3 arch/s390/include/asm/ftrace.h | 32 + arch/s390/kernel/asm-offsets.c | 6 arch/s390/kernel/mcount.S | 12 arch/x86/Kconfig | 4 arch/x86/include/asm/ftrace.h | 33 - arch/x86/kernel/ftrace.c | 50 +- arch/x86/kernel/ftrace_32.S | 15 arch/x86/kernel/ftrace_64.S | 17 - include/linux/fprobe.h | 57 +- include/linux/ftrace.h | 103 +++ include/linux/ftrace_regs.h | 2 kernel/trace/Kconfig | 22 + kernel/trace/bpf_trace.c | 83 ++- kernel/trace/fgraph.c | 62 +- kernel/trace/fprobe.c | 637 ++++++++++++++------ kernel/trace/ftrace.c | 6 kernel/trace/trace.h | 6 kernel/trace/trace_fprobe.c | 146 ++--- kernel/trace/trace_functions_graph.c | 10 kernel/trace/trace_irqsoff.c | 6 kernel/trace/trace_probe_tmpl.h | 2 kernel/trace/trace_sched_wakeup.c | 6 kernel/trace/trace_selftest.c | 11 lib/test_fprobe.c | 51 -- samples/fprobe/fprobe_example.c | 4 .../test.d/dynevent/add_remove_fprobe_repeat.tc | 19 + .../ftrace/test.d/dynevent/fprobe_syntax_errors.tc | 4 48 files changed, 1160 insertions(+), 608 deletions(-) create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_repeat.tc
--
Masami Hiramatsu (Google) <[email protected]>
Masami Hiramatsu (Google)
maintainerPATCH v17 1/16 function_graph: Pass ftrace_regs to entryfunc
From: Masami Hiramatsu (Google) <[email protected]>
Pass ftrace_regs to the fgraph_ops::entryfunc(). If ftrace_regs is not available, it passes a NULL instead. User callback function can access some registers (including return address) via this ftrace_regs.
Note that the ftrace_regs can be NULL when the arch does NOT define:HAVE_DYNAMIC_FTRACE_WITH_ARGS or HAVE_DYNAMIC_FTRACE_WITH_REGS. More specifically, if HAVE_DYNAMIC_FTRACE_WITH_REGS is defined but not the HAVE_DYNAMIC_FTRACE_WITH_ARGS, and the ftrace ops used to register the function callback does not set FTRACE_OPS_FL_SAVE_REGS. In this case, ftrace_regs can be NULL in user callback.
---
Changes in v16:
- Add a note when the ftrace_regs can be NULL.
- Update against for the latest kernel.
Changes in v11:
- Update for the latest for-next branch.
Changes in v8:
- Just pass ftrace_regs to the handler instead of adding a new entryregfunc.
- Update riscv ftrace_graph_func().
Changes in v3:
- Update for new multiple fgraph.
--- arch/arm64/kernel/ftrace.c | 20 +++++++++++- arch/loongarch/kernel/ftrace_dyn.c | 10 +++++- arch/powerpc/kernel/trace/ftrace.c | 2 + arch/powerpc/kernel/trace/ftrace_64_pg.c | 10 ++++-- arch/riscv/kernel/ftrace.c | 17 ++++++++++ arch/x86/kernel/ftrace.c | 50 +++++++++++++++++++++--------- include/linux/ftrace.h | 17 ++++++++-- kernel/trace/fgraph.c | 25 +++++++++------ kernel/trace/ftrace.c | 3 +- kernel/trace/trace.h | 3 +- kernel/trace/trace_functions_graph.c | 3 +- kernel/trace/trace_irqsoff.c | 3 +- kernel/trace/trace_sched_wakeup.c | 3 +- kernel/trace/trace_selftest.c | 8 +++-- 14 files changed, 129 insertions(+), 45 deletions(-)
arch/arm64/kernel/ftrace.c +19 -1
@@ -481,7 +481,25 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,void ftrace_graph_func (unsigned long ip,unsigned long parent_ip,struct ftrace_ops *op,struct ftrace_regs *fregs) { -prepare_ftrace_return (ip, &arch_ftrace_regs (fregs)->lr,arch_ftrace_regs (fregs)->fp); +unsigned long return_hooker = (unsigned long )&return_to_handler; +unsigned long frame_pointer =arch_ftrace_regs (fregs)->fp; +unsigned long *parent = &arch_ftrace_regs (fregs)->lr; +unsigned long old; + +if (unlikely (atomic_read (¤t->tracing_graph_pause))) +return ; + +/* +* Note: +* No protection against faulting at *parent, which may be seen +* on other archs. It's unlikely on AArch64. +*/ + old = *parent; + +if (!function_graph_enter_regs (old, ip, frame_pointer, + (void *)frame_pointer, fregs)) { + *parent = return_hooker; + } }#else /*
arch/loongarch/kernel/ftrace_dyn.c +9 -1
@@ -243,8 +243,16 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, {struct pt_regs *regs = &arch_ftrace_regs (fregs)->regs;unsigned long *parent = (unsigned long *)®s->regs[1 ]; +unsigned long return_hooker = (unsigned long )&return_to_handler; +unsigned long old; + +if (unlikely (atomic_read (¤t->tracing_graph_pause))) +return ; + + old = *parent; -prepare_ftrace_return (ip, (unsigned long *)parent); +if (!function_graph_enter_regs (old, ip,0 , parent, fregs)) + *parent = return_hooker; }#else static int ftrace_modify_graph_caller (bool enable)
arch/powerpc/kernel/trace/ftrace.c +1 -1
@@ -434,7 +434,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,if (bit <0 ) goto out; -if (!function_graph_enter (parent_ip, ip,0 , (unsigned long *)sp)) +if (!function_graph_enter_regs (parent_ip, ip,0 , (unsigned long *)sp, fregs)) parent_ip =ppc_function_entry (return_to_handler);ftrace_test_recursion_unlock (bit);
arch/powerpc/kernel/trace/ftrace_64_pg.c +6 -4
@@ -800,7 +800,8 @@ int ftrace_disable_ftrace_graph_caller(void)* in current thread info. Return the address we want to divert to. */ static unsigned long -__prepare_ftrace_return (unsigned long parent,unsigned long ip,unsigned long sp) +__prepare_ftrace_return (unsigned long parent,unsigned long ip,unsigned long sp, +struct ftrace_regs *fregs) {unsigned long return_hooker;int bit;
@@ -817,7 +818,7 @@ __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp return_hooker =ppc_function_entry (return_to_handler); -if (!function_graph_enter (parent, ip,0 , (unsigned long *)sp)) +if (!function_graph_enter_regs (parent, ip,0 , (unsigned long *)sp, fregs)) parent = return_hooker;ftrace_test_recursion_unlock (bit);
@@ -829,13 +830,14 @@ __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long spvoid ftrace_graph_func (unsigned long ip,unsigned long parent_ip,struct ftrace_ops *op,struct ftrace_regs *fregs) { -arch_ftrace_regs (fregs)->regs.link =__prepare_ftrace_return (parent_ip, ip,arch_ftrace_regs (fregs)->regs.gpr[1 ]); +arch_ftrace_regs (fregs)->regs.link =__prepare_ftrace_return (parent_ip, ip, +arch_ftrace_regs (fregs)->regs.gpr[1 ], fregs); }#else unsigned long prepare_ftrace_return (unsigned long parent,unsigned long ip,unsigned long sp) { -return __prepare_ftrace_return (parent, ip, sp); +return __prepare_ftrace_return (parent, ip, sp,NULL ); }#endif #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
arch/riscv/kernel/ftrace.c +16 -1
@@ -214,7 +214,22 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,void ftrace_graph_func (unsigned long ip,unsigned long parent_ip,struct ftrace_ops *op,struct ftrace_regs *fregs) { -prepare_ftrace_return (&arch_ftrace_regs (fregs)->ra, ip,arch_ftrace_regs (fregs)->s0); +unsigned long return_hooker = (unsigned long )&return_to_handler; +unsigned long frame_pointer =arch_ftrace_regs (fregs)->s0; +unsigned long *parent = &arch_ftrace_regs (fregs)->ra; +unsigned long old; + +if (unlikely (atomic_read (¤t->tracing_graph_pause))) +return ; + +/* +* We don't suffer access faults, so no extra fault-recovery assembly +* is needed here. +*/ + old = *parent; + +if (!function_graph_enter_regs (old, ip, frame_pointer, parent, fregs)) + *parent = return_hooker; }#else /* CONFIG_DYNAMIC_FTRACE_WITH_ARGS */ extern void ftrace_graph_call (void );
arch/x86/kernel/ftrace.c +35 -15
72 lines not on this page · raw message
include/linux/ftrace.h +13 -4
@@ -1071,10 +1071,12 @@ struct fgraph_ops;typedef void (*trace_func_graph_ret_t )(struct ftrace_graph_ret *,struct fgraph_ops *);/* return */ typedef int (*trace_func_graph_ent_t )(struct ftrace_graph_ent *, -struct fgraph_ops *);/* entry */ +struct fgraph_ops *, +struct ftrace_regs *);/* entry */ extern int ftrace_graph_entry_stub (struct ftrace_graph_ent *trace, -struct fgraph_ops *gops); +struct fgraph_ops *gops, +struct ftrace_regs *fregs);bool ftrace_pids_enabled (struct ftrace_ops *ops);#ifdef CONFIG_FUNCTION_GRAPH_TRACER
@@ -1114,8 +1116,15 @@ struct ftrace_ret_stack {extern void return_to_handler (void );extern int -function_graph_enter (unsigned long ret,unsigned long func, -unsigned long frame_pointer,unsigned long *retp); +function_graph_enter_regs (unsigned long ret,unsigned long func, +unsigned long frame_pointer,unsigned long *retp, +struct ftrace_regs *fregs); + +static inline int function_graph_enter (unsigned long ret,unsigned long func, +unsigned long fp,unsigned long *retp) +{ +return function_graph_enter_regs (ret, func, fp, retp,NULL ); +}struct ftrace_ret_stack *ftrace_graph_get_ret_stack (struct task_struct *task,int skip);
kernel/trace/fgraph.c +15 -10
@@ -290,7 +290,8 @@ static inline unsigned long make_data_type_val(int idx, int size, int offset) }/* ftrace_graph_entry set to this to tell some archs to run function graph */ -static int entry_run (struct ftrace_graph_ent *trace,struct fgraph_ops *ops) +static int entry_run (struct ftrace_graph_ent *trace,struct fgraph_ops *ops, +struct ftrace_regs *fregs) {return 0 ; }
@@ -518,7 +519,8 @@ int __weak ftrace_disable_ftrace_graph_caller(void)#endif int ftrace_graph_entry_stub (struct ftrace_graph_ent *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) {return 0 ; }
@@ -642,8 +644,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,#endif /* If the caller does not use ftrace, call this function. */ -int function_graph_enter (unsigned long ret,unsigned long func, -unsigned long frame_pointer,unsigned long *retp) +int function_graph_enter_regs (unsigned long ret,unsigned long func, +unsigned long frame_pointer,unsigned long *retp, +struct ftrace_regs *fregs) {struct ftrace_graph_ent trace;unsigned long bitmap =0 ;
@@ -661,7 +664,7 @@ int function_graph_enter(unsigned long ret, unsigned long func,if (static_branch_likely (&fgraph_do_direct)) {int save_curr_ret_stack = current->curr_ret_stack; -if (static_call (fgraph_func)(&trace, fgraph_direct_gops)) +if (static_call (fgraph_func)(&trace, fgraph_direct_gops, fregs)) bitmap |=BIT (fgraph_direct_gops->idx);else /* Clear out any saved storage */
@@ -679,7 +682,7 @@ int function_graph_enter(unsigned long ret, unsigned long func, save_curr_ret_stack = current->curr_ret_stack;if (ftrace_ops_test (&gops->ops, func,NULL ) && - gops->entryfunc (&trace, gops)) + gops->entryfunc (&trace, gops, fregs)) bitmap |=BIT (i);else /* Clear out any saved storage */
@@ -977,7 +980,7 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,static struct ftrace_ops graph_ops = { .func = ftrace_graph_func, - .flags =FTRACE_OPS_GRAPH_STUB , + .flags =FTRACE_OPS_GRAPH_STUB |FTRACE_OPS_FL_SAVE_ARGS , #ifdef FTRACE_GRAPH_TRAMP_ADDR .trampoline =FTRACE_GRAPH_TRAMP_ADDR , /* trampoline_size is only needed for dynamically allocated tramps */
@@ -987,7 +990,8 @@ static struct ftrace_ops graph_ops = {void fgraph_init_ops (struct ftrace_ops *dst_ops,struct ftrace_ops *src_ops) { - dst_ops->flags =FTRACE_OPS_FL_PID |FTRACE_OPS_GRAPH_STUB ; + dst_ops->flags =FTRACE_OPS_FL_PID |FTRACE_OPS_GRAPH_STUB | +FTRACE_OPS_FL_SAVE_ARGS ;#ifdef CONFIG_DYNAMIC_FTRACE if (src_ops) {
@@ -1159,7 +1163,8 @@ void ftrace_graph_exit_task(struct task_struct *t)#ifdef CONFIG_DYNAMIC_FTRACE static int fgraph_pid_func (struct ftrace_graph_ent *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) {struct trace_array *tr = gops->ops.private;int pid;
@@ -1173,7 +1178,7 @@ static int fgraph_pid_func(struct ftrace_graph_ent *trace,return 0 ; } -return gops->saved_func (trace, gops); +return gops->saved_func (trace, gops, fregs); }void fgraph_update_pid_func (void )
kernel/trace/ftrace.c +2 -1
@@ -827,7 +827,8 @@ struct profile_fgraph_data { };static int profile_graph_entry (struct ftrace_graph_ent *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) {struct profile_fgraph_data *profile_data;
kernel/trace/trace.h +2 -1
@@ -695,7 +695,8 @@ void trace_default_header(struct seq_file *m);void print_trace_header (struct seq_file *m,struct trace_iterator *iter);void trace_graph_return (struct ftrace_graph_ret *trace,struct fgraph_ops *gops); -int trace_graph_entry (struct ftrace_graph_ent *trace,struct fgraph_ops *gops); +int trace_graph_entry (struct ftrace_graph_ent *trace,struct fgraph_ops *gops, +struct ftrace_regs *fregs);void tracing_start_cmdline_record (void );void tracing_stop_cmdline_record (void );
kernel/trace/trace_functions_graph.c +2 -1
@@ -177,7 +177,8 @@ struct fgraph_times { };int trace_graph_entry (struct ftrace_graph_ent *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) {unsigned long *task_var =fgraph_get_task_var (gops);struct trace_array *tr = gops->private;
kernel/trace/trace_irqsoff.c +2 -1
@@ -176,7 +176,8 @@ static int irqsoff_display_graph(struct trace_array *tr, int set) }static int irqsoff_graph_entry (struct ftrace_graph_ent *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) {struct trace_array *tr = irqsoff_trace;struct trace_array_cpu *data;
kernel/trace/trace_sched_wakeup.c +2 -1
@@ -113,7 +113,8 @@ static int wakeup_display_graph(struct trace_array *tr, int set) }static int wakeup_graph_entry (struct ftrace_graph_ent *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) {struct trace_array *tr = wakeup_trace;struct trace_array_cpu *data;
kernel/trace/trace_selftest.c +5 -3
@@ -774,7 +774,8 @@ struct fgraph_fixture { };static __init int store_entry (struct ftrace_graph_ent *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) { struct fgraph_fixture *fixture = container_of(gops, struct fgraph_fixture, gops);const char *type = fixture->store_type_name;
@@ -1025,7 +1026,8 @@ static unsigned int graph_hang_thresh;/* Wrap the real function entry probe to avoid possible hanging */ static int trace_graph_entry_watchdog (struct ftrace_graph_ent *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) {/* This is harmlessly racy, we want to approximately detect a hang */ if (unlikely (++graph_hang_thresh >GRAPH_MAX_FUNC_TEST )) {
@@ -1039,7 +1041,7 @@ static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace,return 0 ; } -return trace_graph_entry (trace, gops); +return trace_graph_entry (trace, gops, fregs); }static struct fgraph_ops fgraph_ops__initdata = {
Steven Rostedt
maintainerRe: [PATCH v17 01/16] function_graph: Pass ftrace_regs to entryfunc
Quoted 5 lines · On Wed, 16 Oct 2024 09:57:55 +0900 "Masami Hiramatsu (Google)"…
From: Masami Hiramatsu (Google) <[email protected]>
Pass
ftrace_regsto thefgraph_ops::entryfunc(). Ifftrace_regsis not available, it passes a NULL instead. User callback function can access some registers (including return address) via thisftrace_regs.
BTW, you can use "fgraph:" for short. It makes the subject easier to read. I've been using that instead of "function_graph:" lately.
-- Steve
Masami Hiramatsu (Google)
maintainerRe: [PATCH v17 01/16] function_graph: Pass ftrace_regs to entryfunc
Quoted 11 lines · On Wed, 16 Oct 2024 09:53:25 -0400 Steven Rostedt <[email protected]> wrote:
Quoted 5 lines · On Wed, 16 Oct 2024 09:57:55 +0900 "Masami Hiramatsu (Google)"…
From: Masami Hiramatsu (Google) <[email protected]>
Pass
ftrace_regsto thefgraph_ops::entryfunc(). Ifftrace_regsis not available, it passes a NULL instead. User callback function can access some registers (including return address) via thisftrace_regs.BTW, you can use "fgraph:" for short. It makes the subject easier to read. I've been using that instead of "
function_graph:" lately.
OK, I'll use it in the next version.
Thank you,
Quoted 2 lines
-- Steve
Signature · 1 line
Masami Hiramatsu (Google) <[email protected]>
Will Deacon
maintainerRe: [PATCH v17 01/16] function_graph: Pass ftrace_regs to entryfunc
In reply to Masami Hiramatsu (Google)Quoted 78 lines · Masami Hiramatsu (Google)
From: Masami Hiramatsu (Google) <[email protected]>
Pass
ftrace_regsto thefgraph_ops::entryfunc(). Ifftrace_regsis not available, it passes a NULL instead. User callback function can access some registers (including return address) via thisftrace_regs.Note that the
ftrace_regscan be NULL when the arch does NOT define:HAVE_DYNAMIC_FTRACE_WITH_ARGSorHAVE_DYNAMIC_FTRACE_WITH_REGS. More specifically, ifHAVE_DYNAMIC_FTRACE_WITH_REGSis defined but not theHAVE_DYNAMIC_FTRACE_WITH_ARGS, and the ftrace ops used to register the function callback does not setFTRACE_OPS_FL_SAVE_REGS. In this case,ftrace_regscan be NULL in user callback.Signed-off-by Masami Hiramatsu (Google) <[email protected]>Cc Steven Rostedt <[email protected]>Cc Mark Rutland <[email protected]>Cc Catalin Marinas <[email protected]>Cc Will Deacon <[email protected]>Cc Huacai Chen <[email protected]>Cc WANG Xuerui <[email protected]>Cc Michael Ellerman <[email protected]>Cc Nicholas Piggin <[email protected]>Cc Christophe Leroy <[email protected]>Cc Naveen N Rao <[email protected]>Cc Madhavan Srinivasan <[email protected]>Cc Paul Walmsley <[email protected]>Cc Palmer Dabbelt <[email protected]>Cc Albert Ou <[email protected]>Cc Thomas Gleixner <[email protected]>Cc Ingo Molnar <[email protected]>Cc Borislav Petkov <[email protected]>Cc Dave Hansen <[email protected]>Cc "H. Peter Anvin" <[email protected]>Cc Mathieu Desnoyers <[email protected]>---
Changes in v16:
- Add a note when theftrace_regscan be NULL.
- Update against for the latest kernel.
Changes in v11:
- Update for the latest for-next branch.
Changes in v8:
- Just passftrace_regsto the handler instead of adding a new entryregfunc.
- Update riscvftrace_graph_func().
Changes in v3:
- Update for new multiple fgraph.--- arch/arm64/kernel/ftrace.c | 20 +++++++++++- arch/loongarch/kernel/ftrace_dyn.c | 10 +++++- arch/powerpc/kernel/trace/ftrace.c | 2 + arch/powerpc/kernel/trace/ftrace_64_pg.c | 10 ++++-- arch/riscv/kernel/ftrace.c | 17 ++++++++++ arch/x86/kernel/ftrace.c | 50 +++++++++++++++++++++--------- include/linux/ftrace.h | 17 ++++++++-- kernel/trace/fgraph.c | 25 +++++++++------ kernel/trace/ftrace.c | 3 +- kernel/trace/trace.h | 3 +- kernel/trace/trace_functions_graph.c | 3 +- kernel/trace/trace_irqsoff.c | 3 +- kernel/trace/trace_sched_wakeup.c | 3 +- kernel/trace/trace_selftest.c | 8 +++-- 14 files changed, 129 insertions(+), 45 deletions(-)arch/arm64/kernel/ftrace.c +4
-1@@ -481,7 +481,25 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,void ftrace_graph_func (unsigned long ip,unsigned long parent_ip,struct ftrace_ops *op,struct ftrace_regs *fregs) { -prepare_ftrace_return (ip, &arch_ftrace_regs (fregs)->lr,arch_ftrace_regs (fregs)->fp); +unsigned long return_hooker = (unsigned long )&return_to_handler; +unsigned long frame_pointer =arch_ftrace_regs (fregs)->fp; +unsigned long *parent = &arch_ftrace_regs (fregs)->lr; +unsigned long old;
arch/arm64/kernel/ftrace.c void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent, · line 497
Quoted 10 lines
arch/arm64/kernel/ftrace.c +10
-0+ +if (unlikely (atomic_read (¤t->tracing_graph_pause))) +return ; + +/* +* Note: +* No protection against faulting at *parent, which may be seen +* on other archs. It's unlikely on AArch64. +*/ + old = *parent;
Sorry to pick on this line again, but the comment is very non-committal] and I think this is something on which we need to be definitive.
Either the access can fault, and we should handle it, or it will never fault and we don't need to handle it. Saying it's unlikely means we need to handle it :)
Will
Masami Hiramatsu (Google)
maintainerRe: [PATCH v17 01/16] function_graph: Pass ftrace_regs to entryfunc
Quoted 84 lines · On Mon, 21 Oct 2024 18:03:40 +0100 Will Deacon <[email protected]> wrote:
Quoted 83 lines · Masami Hiramatsu (Google)
From: Masami Hiramatsu (Google) <[email protected]>
Pass
ftrace_regsto thefgraph_ops::entryfunc(). Ifftrace_regsis not available, it passes a NULL instead. User callback function can access some registers (including return address) via thisftrace_regs.Note that the
ftrace_regscan be NULL when the arch does NOT define:HAVE_DYNAMIC_FTRACE_WITH_ARGSorHAVE_DYNAMIC_FTRACE_WITH_REGS. More specifically, ifHAVE_DYNAMIC_FTRACE_WITH_REGSis defined but not theHAVE_DYNAMIC_FTRACE_WITH_ARGS, and the ftrace ops used to register the function callback does not setFTRACE_OPS_FL_SAVE_REGS. In this case,ftrace_regscan be NULL in user callback.Signed-off-by Masami Hiramatsu (Google) <[email protected]>Cc Steven Rostedt <[email protected]>Cc Mark Rutland <[email protected]>Cc Catalin Marinas <[email protected]>Cc Will Deacon <[email protected]>Cc Huacai Chen <[email protected]>Cc WANG Xuerui <[email protected]>Cc Michael Ellerman <[email protected]>Cc Nicholas Piggin <[email protected]>Cc Christophe Leroy <[email protected]>Cc Naveen N Rao <[email protected]>Cc Madhavan Srinivasan <[email protected]>Cc Paul Walmsley <[email protected]>Cc Palmer Dabbelt <[email protected]>Cc Albert Ou <[email protected]>Cc Thomas Gleixner <[email protected]>Cc Ingo Molnar <[email protected]>Cc Borislav Petkov <[email protected]>Cc Dave Hansen <[email protected]>Cc "H. Peter Anvin" <[email protected]>Cc Mathieu Desnoyers <[email protected]>---
Changes in v16:
- Add a note when theftrace_regscan be NULL.
- Update against for the latest kernel.
Changes in v11:
- Update for the latest for-next branch.
Changes in v8:
- Just passftrace_regsto the handler instead of adding a new entryregfunc.
- Update riscvftrace_graph_func().
Changes in v3:
- Update for new multiple fgraph.--- arch/arm64/kernel/ftrace.c | 20 +++++++++++- arch/loongarch/kernel/ftrace_dyn.c | 10 +++++- arch/powerpc/kernel/trace/ftrace.c | 2 + arch/powerpc/kernel/trace/ftrace_64_pg.c | 10 ++++-- arch/riscv/kernel/ftrace.c | 17 ++++++++++ arch/x86/kernel/ftrace.c | 50 +++++++++++++++++++++--------- include/linux/ftrace.h | 17 ++++++++-- kernel/trace/fgraph.c | 25 +++++++++------ kernel/trace/ftrace.c | 3 +- kernel/trace/trace.h | 3 +- kernel/trace/trace_functions_graph.c | 3 +- kernel/trace/trace_irqsoff.c | 3 +- kernel/trace/trace_sched_wakeup.c | 3 +- kernel/trace/trace_selftest.c | 8 +++-- 14 files changed, 129 insertions(+), 45 deletions(-)arch/arm64/kernel/ftrace.c +9
-1@@ -481,7 +481,25 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,void ftrace_graph_func (unsigned long ip,unsigned long parent_ip,struct ftrace_ops *op,struct ftrace_regs *fregs) { -prepare_ftrace_return (ip, &arch_ftrace_regs (fregs)->lr,arch_ftrace_regs (fregs)->fp); +unsigned long return_hooker = (unsigned long )&return_to_handler; +unsigned long frame_pointer =arch_ftrace_regs (fregs)->fp; +unsigned long *parent = &arch_ftrace_regs (fregs)->lr; +unsigned long old; + +if (unlikely (atomic_read (¤t->tracing_graph_pause))) +return ; + +/*
Quoted 8 lines
arch/arm64/kernel/ftrace.c void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent, · line 497
Quoted 5 lines
arch/arm64/kernel/ftrace.c +5
-0+* Note: +* No protection against faulting at *parent, which may be seen +* on other archs. It's unlikely on AArch64. +*/ + old = *parent;Sorry to pick on this line again, but the comment is very non-committal] and I think this is something on which we need to be definitive.
Agreed. I think this does not happen because it is a part of __arch_ftrace_regs, which is stored on kernel stack.
I copied it from prepare_ftrace_return(), so that also need to be changed too.
Let me remove this comment.
Thank you,
Quoted 7 lines
Either the access can fault, and we should handle it, or it will never fault and we don't need to handle it. Saying it's unlikely means we need to handle it :)
Will
Signature · 1 line
Masami Hiramatsu (Google) <[email protected]>
Masami Hiramatsu (Google)
maintainerPATCH v17 2/16 function_graph: Replace fgraph_ret_regs with ftrace_regs
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Use ftrace_regs instead of fgraph_ret_regs for tracing return value on function_graph tracer because of simplifying the callback interface.
The CONFIG_HAVE_FUNCTION_GRAPH_RETVAL is also replaced by CONFIG_HAVE_FUNCTION_GRAPH_FREGS.
---
Changes in v17:
- Fixes s390 return_to_handler according to Heiko's advice.
Changes in v16:
- According to the recent ftrace_regs.h change, override ftrace_regs_get_frame_pointer() if needed.
- s390: keep stack_frame on stack, just replace fgraph_ret_regs with ftrace_regs.
Changes in v8:
- Newly added.
--- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/ftrace.h | 23 ++++++----------------- arch/arm64/kernel/asm-offsets.c | 12 ------------ arch/arm64/kernel/entry-ftrace.S | 32 ++++++++++++++++++-------------- arch/loongarch/Kconfig | 2 +- arch/loongarch/include/asm/ftrace.h | 26 ++++---------------------- arch/loongarch/kernel/asm-offsets.c | 12 ------------ arch/loongarch/kernel/mcount.S | 17 ++++++++++------- arch/loongarch/kernel/mcount_dyn.S | 14 +++++++------- arch/riscv/Kconfig | 2 +- arch/riscv/include/asm/ftrace.h | 26 +++++--------------------- arch/riscv/kernel/mcount.S | 24 +++++++++++++----------- arch/s390/Kconfig | 2 +- arch/s390/include/asm/ftrace.h | 24 +++++++----------------- arch/s390/kernel/asm-offsets.c | 6 ------ arch/s390/kernel/mcount.S | 12 ++++++------ arch/x86/Kconfig | 2 +- arch/x86/include/asm/ftrace.h | 20 -------------------- arch/x86/kernel/ftrace_32.S | 15 +++++++++------ arch/x86/kernel/ftrace_64.S | 17 +++++++++-------- include/linux/ftrace.h | 12 +++++++++--- include/linux/ftrace_regs.h | 2 ++ kernel/trace/Kconfig | 4 ++-- kernel/trace/fgraph.c | 21 +++++++++------------ 24 files changed, 121 insertions(+), 207 deletions(-)
arch/arm64/Kconfig +1 -0
@@ -215,6 +215,7 @@ config ARM64 select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FUNCTION_TRACER select HAVE_FUNCTION_ERROR_INJECTION + select HAVE_FUNCTION_GRAPH_FREGS select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_GRAPH_RETVAL select HAVE_GCC_PLUGINS
arch/arm64/include/asm/ftrace.h +6 -17
@@ -129,6 +129,12 @@ ftrace_override_function_with_return(struct ftrace_regs *fregs)arch_ftrace_regs (fregs)->pc =arch_ftrace_regs (fregs)->lr; } +static __always_inline unsigned long +ftrace_regs_get_frame_pointer (const struct ftrace_regs *fregs) +{ +return arch_ftrace_regs (fregs)->fp; +} +int ftrace_regs_query_register_offset (const char *name);int ftrace_init_nop (struct module *mod,struct dyn_ftrace *rec);
@@ -186,23 +192,6 @@ static inline bool arch_syscall_match_sym_name(const char *sym,#ifndef __ASSEMBLY__#ifdef CONFIG_FUNCTION_GRAPH_TRACER -struct fgraph_ret_regs { -/* x0 - x7 */ -unsigned long regs[8 ]; - -unsigned long fp; -unsigned long __unused; -}; - -static inline unsigned long fgraph_ret_regs_return_value (struct fgraph_ret_regs *ret_regs) -{ -return ret_regs->regs[0 ]; -} - -static inline unsigned long fgraph_ret_regs_frame_pointer (struct fgraph_ret_regs *ret_regs) -{ -return ret_regs->fp; -}void prepare_ftrace_return (unsigned long self_addr,unsigned long *parent,unsigned long frame_pointer);
arch/arm64/kernel/asm-offsets.c +0 -12
@@ -201,18 +201,6 @@ int main(void)DEFINE (FTRACE_OPS_FUNC , offsetof(struct ftrace_ops , func));#endif BLANK (); -#ifdef CONFIG_FUNCTION_GRAPH_TRACER - DEFINE(FGRET_REGS_X0, offsetof(struct fgraph_ret_regs, regs[0])); - DEFINE(FGRET_REGS_X1, offsetof(struct fgraph_ret_regs, regs[1])); - DEFINE(FGRET_REGS_X2, offsetof(struct fgraph_ret_regs, regs[2])); - DEFINE(FGRET_REGS_X3, offsetof(struct fgraph_ret_regs, regs[3])); - DEFINE(FGRET_REGS_X4, offsetof(struct fgraph_ret_regs, regs[4])); - DEFINE(FGRET_REGS_X5, offsetof(struct fgraph_ret_regs, regs[5])); - DEFINE(FGRET_REGS_X6, offsetof(struct fgraph_ret_regs, regs[6])); - DEFINE(FGRET_REGS_X7, offsetof(struct fgraph_ret_regs, regs[7])); -DEFINE (FGRET_REGS_FP , offsetof(struct fgraph_ret_regs , fp)); -DEFINE (FGRET_REGS_SIZE ,sizeof (struct fgraph_ret_regs )); -#endif #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS DEFINE (FTRACE_OPS_DIRECT_CALL , offsetof(struct ftrace_ops , direct_call));#endif
arch/arm64/kernel/entry-ftrace.S +18 -14
@@ -329,24 +329,28 @@ SYM_FUNC_END(ftrace_stub_graph) * @fp is checked against the value passed by ftrace_graph_caller(). */ SYM_CODE_START(return_to_handler) - /* save return value regs */ - sub sp, sp, #FGRET_REGS_SIZE - stp x0, x1, [sp, #FGRET_REGS_X0] - stp x2, x3, [sp, #FGRET_REGS_X2] - stp x4, x5, [sp, #FGRET_REGS_X4] - stp x6, x7, [sp, #FGRET_REGS_X6] - str x29, [sp, #FGRET_REGS_FP] // parent's fp + /* Make room for ftrace_regs */ + sub sp, sp, #FREGS_SIZE + + /* Save return value regs */ + stp x0, x1, [sp, #FREGS_X0] + stp x2, x3, [sp, #FREGS_X2] + stp x4, x5, [sp, #FREGS_X4] + stp x6, x7, [sp, #FREGS_X6] + + /* Save the callsite's FP */ + str x29, [sp, #FREGS_FP] mov x0, sp - bl ftrace_return_to_handler // addr = ftrace_return_to_hander(regs); + bl ftrace_return_to_handler // addr = ftrace_return_to_hander(fregs); mov x30, x0 // restore the original return address - /* restore return value regs */ - ldp x0, x1, [sp, #FGRET_REGS_X0] - ldp x2, x3, [sp, #FGRET_REGS_X2] - ldp x4, x5, [sp, #FGRET_REGS_X4] - ldp x6, x7, [sp, #FGRET_REGS_X6] - add sp, sp, #FGRET_REGS_SIZE + /* Restore return value regs */ + ldp x0, x1, [sp, #FREGS_X0] + ldp x2, x3, [sp, #FREGS_X2] + ldp x4, x5, [sp, #FREGS_X4] + ldp x6, x7, [sp, #FREGS_X6] + add sp, sp, #FREGS_SIZE ret SYM_CODE_END(return_to_handler)
arch/loongarch/Kconfig +1 -1
@@ -135,7 +135,7 @@ config LOONGARCH select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FUNCTION_ARG_ACCESS_API select HAVE_FUNCTION_ERROR_INJECTION - select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER + select HAVE_FUNCTION_GRAPH_FREGS select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_TRACER select HAVE_GCC_PLUGINS
arch/loongarch/include/asm/ftrace.h +4 -22
@@ -57,6 +57,10 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, unsigned long ip)instruction_pointer_set (&arch_ftrace_regs (fregs)->regs, ip); } +#undef ftrace_regs_get_frame_pointer +#define ftrace_regs_get_frame_pointer (fregs) \ + (arch_ftrace_regs(fregs)->regs.regs[22]) +#define ftrace_graph_func ftrace_graph_funcvoid ftrace_graph_func (unsigned long ip,unsigned long parent_ip,struct ftrace_ops *op,struct ftrace_regs *fregs);
@@ -78,26 +82,4 @@ __arch_ftrace_set_direct_caller(struct pt_regs *regs, unsigned long addr)#endif /* CONFIG_FUNCTION_TRACER */ -#ifndef __ASSEMBLY__ -#ifdef CONFIG_FUNCTION_GRAPH_TRACER -struct fgraph_ret_regs { -/* a0 - a1 */ -unsigned long regs[2 ]; - -unsigned long fp; -unsigned long __unused; -}; - -static inline unsigned long fgraph_ret_regs_return_value (struct fgraph_ret_regs *ret_regs) -{ -return ret_regs->regs[0 ]; -} - -static inline unsigned long fgraph_ret_regs_frame_pointer (struct fgraph_ret_regs *ret_regs) -{ -return ret_regs->fp; -} -#endif /* ifdef CONFIG_FUNCTION_GRAPH_TRACER */ -#endif -#endif /* _ASM_LOONGARCH_FTRACE_H */
arch/loongarch/kernel/asm-offsets.c +0 -12
@@ -279,18 +279,6 @@ static void __used output_pbe_defines(void) }#endif -#ifdef CONFIG_FUNCTION_GRAPH_TRACER -static void __used output_fgraph_ret_regs_defines (void ) -{ -COMMENT ("LoongArch fgraph_ret_regs offsets." ); -OFFSET (FGRET_REGS_A0 , fgraph_ret_regs, regs[0 ]); -OFFSET (FGRET_REGS_A1 , fgraph_ret_regs, regs[1 ]); -OFFSET (FGRET_REGS_FP , fgraph_ret_regs, fp); -DEFINE (FGRET_REGS_SIZE ,sizeof (struct fgraph_ret_regs )); -BLANK (); -} -#endif -static void __used output_kvm_defines (void ) {COMMENT ("KVM/LoongArch Specific offsets." );
arch/loongarch/kernel/mcount.S +10 -7
@@ -79,10 +79,11 @@ SYM_FUNC_START(ftrace_graph_caller) SYM_FUNC_END(ftrace_graph_caller) SYM_FUNC_START(return_to_handler) - PTR_ADDI sp, sp, -FGRET_REGS_SIZE - PTR_S a0, sp, FGRET_REGS_A0 - PTR_S a1, sp, FGRET_REGS_A1 - PTR_S zero, sp, FGRET_REGS_FP + /* Save return value regs */ + PTR_ADDI sp, sp, -PT_SIZE + PTR_S a0, sp, PT_R4 + PTR_S a1, sp, PT_R5 + PTR_S zero, sp, PT_R22 move a0, sp bl ftrace_return_to_handler
@@ -90,9 +91,11 @@ SYM_FUNC_START(return_to_handler) /* Restore the real parent address: a0 -> ra */ move ra, a0 - PTR_L a0, sp, FGRET_REGS_A0 - PTR_L a1, sp, FGRET_REGS_A1 - PTR_ADDI sp, sp, FGRET_REGS_SIZE + /* Restore return value regs */ + PTR_L a0, sp, PT_R4 + PTR_L a1, sp, PT_R5 + PTR_ADDI sp, sp, PT_SIZE + jr ra SYM_FUNC_END(return_to_handler) #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
arch/loongarch/kernel/mcount_dyn.S +7 -7
@@ -140,19 +140,19 @@ SYM_CODE_END(ftrace_graph_caller) SYM_CODE_START(return_to_handler) UNWIND_HINT_UNDEFINED /* Save return value regs */ - PTR_ADDI sp, sp, -FGRET_REGS_SIZE - PTR_S a0, sp, FGRET_REGS_A0 - PTR_S a1, sp, FGRET_REGS_A1 - PTR_S zero, sp, FGRET_REGS_FP + PTR_ADDI sp, sp, -PT_SIZE + PTR_S a0, sp, PT_R4 + PTR_S a1, sp, PT_R5 + PTR_S zero, sp, PT_R22 move a0, sp bl ftrace_return_to_handler move ra, a0 /* Restore return value regs */ - PTR_L a0, sp, FGRET_REGS_A0 - PTR_L a1, sp, FGRET_REGS_A1 - PTR_ADDI sp, sp, FGRET_REGS_SIZE + PTR_L a0, sp, PT_R4 + PTR_L a1, sp, PT_R5 + PTR_ADDI sp, sp, PT_SIZE jr ra SYM_CODE_END(return_to_handler)
arch/riscv/Kconfig +1 -1
@@ -144,7 +144,7 @@ config RISCV select HAVE_DYNAMIC_FTRACE_WITH_ARGS if HAVE_DYNAMIC_FTRACE select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL select HAVE_FUNCTION_GRAPH_TRACER - select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER + select HAVE_FUNCTION_GRAPH_FREGS select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !PREEMPTION select HAVE_EBPF_JIT if MMU select HAVE_GUP_FAST if MMU
arch/riscv/include/asm/ftrace.h +5 -21
@@ -168,6 +168,11 @@ static __always_inline unsigned long ftrace_regs_get_stack_pointer(const structreturn arch_ftrace_regs (fregs)->sp; } +static __always_inline unsigned long ftrace_regs_get_frame_pointer (const struct ftrace_regs *fregs) +{ +return arch_ftrace_regs (fregs)->s0; +} +static __always_inline unsigned long ftrace_regs_get_argument (struct ftrace_regs *fregs,unsigned int n) {
@@ -208,25 +213,4 @@ static inline void arch_ftrace_set_direct_caller(struct ftrace_regs *fregs, unsi#endif /* CONFIG_DYNAMIC_FTRACE */ -#ifndef __ASSEMBLY__ -#ifdef CONFIG_FUNCTION_GRAPH_TRACER -struct fgraph_ret_regs { -unsigned long a1; -unsigned long a0; -unsigned long s0; -unsigned long ra; -}; - -static inline unsigned long fgraph_ret_regs_return_value (struct fgraph_ret_regs *ret_regs) -{ -return ret_regs->a0; -} - -static inline unsigned long fgraph_ret_regs_frame_pointer (struct fgraph_ret_regs *ret_regs) -{ -return ret_regs->s0; -} -#endif /* ifdef CONFIG_FUNCTION_GRAPH_TRACER */ -#endif -#endif /* _ASM_RISCV_FTRACE_H */
arch/riscv/kernel/mcount.S +13 -11
@@ -12,6 +12,8 @@ #include <asm/asm-offsets.h> #include <asm/ftrace.h> +#define ABI_SIZE_ON_STACK 80 + .text .macro SAVE_ABI_STATE
@@ -26,12 +28,12 @@ * register if a0 was not saved. */ .macro SAVE_RET_ABI_STATE - addi sp, sp, -4*SZREG - REG_S s0, 2*SZREG(sp) - REG_S ra, 3*SZREG(sp) - REG_S a0, 1*SZREG(sp) - REG_S a1, 0*SZREG(sp) - addi s0, sp, 4*SZREG + addi sp, sp, -ABI_SIZE_ON_STACK + REG_S ra, 1*SZREG(sp) + REG_S s0, 8*SZREG(sp) + REG_S a0, 10*SZREG(sp) + REG_S a1, 11*SZREG(sp) + addi s0, sp, ABI_SIZE_ON_STACK .endm .macro RESTORE_ABI_STATE
@@ -41,11 +43,11 @@ .endm .macro RESTORE_RET_ABI_STATE - REG_L ra, 3*SZREG(sp) - REG_L s0, 2*SZREG(sp) - REG_L a0, 1*SZREG(sp) - REG_L a1, 0*SZREG(sp) - addi sp, sp, 4*SZREG + REG_L ra, 1*SZREG(sp) + REG_L s0, 8*SZREG(sp) + REG_L a0, 10*SZREG(sp) + REG_L a1, 11*SZREG(sp) + addi sp, sp, ABI_SIZE_ON_STACK .endm SYM_TYPED_FUNC_START(ftrace_stub)
arch/s390/Kconfig +1 -1
@@ -184,7 +184,7 @@ config S390 select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FUNCTION_ARG_ACCESS_API select HAVE_FUNCTION_ERROR_INJECTION - select HAVE_FUNCTION_GRAPH_RETVAL + select HAVE_FUNCTION_GRAPH_FREGS select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_TRACER select HAVE_GCC_PLUGINS
arch/s390/include/asm/ftrace.h +7 -17
@@ -62,23 +62,6 @@ static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *return NULL ; } -#ifdef CONFIG_FUNCTION_GRAPH_TRACER -struct fgraph_ret_regs { -unsigned long gpr2; -unsigned long fp; -}; - -static __always_inline unsigned long fgraph_ret_regs_return_value (struct fgraph_ret_regs *ret_regs) -{ -return ret_regs->gpr2; -} - -static __always_inline unsigned long fgraph_ret_regs_frame_pointer (struct fgraph_ret_regs *ret_regs) -{ -return ret_regs->fp; -} -#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ - static __always_inline voidftrace_regs_set_instruction_pointer (struct ftrace_regs *fregs,unsigned long ip)
@@ -86,6 +69,13 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,arch_ftrace_regs (fregs)->regs.psw.addr = ip; } +#undef ftrace_regs_get_frame_pointer +static __always_inline unsigned long +ftrace_regs_get_frame_pointer (struct ftrace_regs *fregs) +{ +return ftrace_regs_get_stack_pointer (fregs); +} +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS /* * When an ftrace registered caller is tracing a function that is
arch/s390/kernel/asm-offsets.c +0 -6
@@ -178,12 +178,6 @@ int main(void)DEFINE (OLDMEM_SIZE ,PARMAREA + offsetof(struct parmarea , oldmem_size));DEFINE (COMMAND_LINE ,PARMAREA + offsetof(struct parmarea , command_line));DEFINE (MAX_COMMAND_LINE_SIZE ,PARMAREA + offsetof(struct parmarea , max_command_line_size)); -#ifdef CONFIG_FUNCTION_GRAPH_TRACER -/* function graph return value tracing */ -OFFSET (__FGRAPH_RET_GPR2, fgraph_ret_regs, gpr2); -OFFSET (__FGRAPH_RET_FP, fgraph_ret_regs, fp); -DEFINE (__FGRAPH_RET_SIZE,sizeof (struct fgraph_ret_regs )); -#endif OFFSET (__FTRACE_REGS_PT_REGS, __arch_ftrace_regs, regs);DEFINE (__FTRACE_REGS_SIZE,sizeof (struct __arch_ftrace_regs ));
arch/s390/kernel/mcount.S +6 -6
@@ -134,14 +134,14 @@ SYM_CODE_END(ftrace_common) SYM_FUNC_START(return_to_handler) stmg %r2,%r5,32(%r15) lgr %r1,%r15 - aghi %r15,-(STACK_FRAME_OVERHEAD+__FGRAPH_RET_SIZE) + # allocate ftrace_regs and stack frame for ftrace_return_to_handler + aghi %r15,-STACK_FRAME_SIZE_FREGS stg %r1,__SF_BACKCHAIN(%r15) - la %r3,STACK_FRAME_OVERHEAD(%r15) - stg %r1,__FGRAPH_RET_FP(%r3) - stg %r2,__FGRAPH_RET_GPR2(%r3) - lgr %r2,%r3 + stg %r2,(STACK_FREGS_PTREGS_GPRS+2*8)(%r15) + stg %r1,(STACK_FREGS_PTREGS_GPRS+15*8)(%r15) + la %r2,STACK_FRAME_OVERHEAD(%r15) brasl %r14,ftrace_return_to_handler - aghi %r15,STACK_FRAME_OVERHEAD+__FGRAPH_RET_SIZE + aghi %r15,STACK_FRAME_SIZE_FREGS lgr %r14,%r2 lmg %r2,%r5,32(%r15) BR_EX %r14
arch/x86/Kconfig +1 -1
@@ -232,7 +232,7 @@ config X86 select HAVE_GUP_FAST select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE select HAVE_FTRACE_MCOUNT_RECORD - select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER + select HAVE_FUNCTION_GRAPH_FREGS if HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) select HAVE_FUNCTION_TRACER select HAVE_GCC_PLUGINS
arch/x86/include/asm/ftrace.h +0 -20
@@ -132,24 +132,4 @@ static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)#endif /* !COMPILE_OFFSETS */ #endif /* !__ASSEMBLY__ */ -#ifndef __ASSEMBLY__ -#ifdef CONFIG_FUNCTION_GRAPH_TRACER -struct fgraph_ret_regs { -unsigned long ax; -unsigned long dx; -unsigned long bp; -}; - -static inline unsigned long fgraph_ret_regs_return_value (struct fgraph_ret_regs *ret_regs) -{ -return ret_regs->ax; -} - -static inline unsigned long fgraph_ret_regs_frame_pointer (struct fgraph_ret_regs *ret_regs) -{ -return ret_regs->bp; -} -#endif /* ifdef CONFIG_FUNCTION_GRAPH_TRACER */ -#endif -#endif /* _ASM_X86_FTRACE_H */
arch/x86/kernel/ftrace_32.S +9 -6
@@ -23,6 +23,8 @@ SYM_FUNC_START(__fentry__) SYM_FUNC_END(__fentry__) EXPORT_SYMBOL(__fentry__) +#define FRAME_SIZE PT_OLDSS+4 + SYM_CODE_START(ftrace_caller) #ifdef CONFIG_FRAME_POINTER
@@ -187,14 +189,15 @@ SYM_CODE_END(ftrace_graph_caller) .globl return_to_handler return_to_handler: - pushl $0 - pushl %edx - pushl %eax + subl $(FRAME_SIZE), %esp + movl $0, PT_EBP(%esp) + movl %edx, PT_EDX(%esp) + movl %eax, PT_EAX(%esp) movl %esp, %eax call ftrace_return_to_handler movl %eax, %ecx - popl %eax - popl %edx - addl $4, %esp # skip ebp + movl %eax, PT_EAX(%esp) + movl %edx, PT_EDX(%esp) + addl $(FRAME_SIZE), %esp JMP_NOSPEC ecx #endif
arch/x86/kernel/ftrace_64.S +9 -8
@@ -348,21 +348,22 @@ STACK_FRAME_NON_STANDARD_FP(__fentry__) SYM_CODE_START(return_to_handler) UNWIND_HINT_UNDEFINED ANNOTATE_NOENDBR - subq $24, %rsp - /* Save the return values */ - movq %rax, (%rsp) - movq %rdx, 8(%rsp) - movq %rbp, 16(%rsp) + /* Save ftrace_regs for function exit context */ + subq $(FRAME_SIZE), %rsp + + movq %rax, RAX(%rsp) + movq %rdx, RDX(%rsp) + movq %rbp, RBP(%rsp) movq %rsp, %rdi call ftrace_return_to_handler movq %rax, %rdi - movq 8(%rsp), %rdx - movq (%rsp), %rax + movq RDX(%rsp), %rdx + movq RAX(%rsp), %rax - addq $24, %rsp + addq $(FRAME_SIZE), %rsp /* * Jump back to the old return address. This cannot be JMP_NOSPEC rdi * since IBT would demand that contain ENDBR, which simply isn't so for
include/linux/ftrace.h +9 -3
@@ -43,9 +43,8 @@ struct dyn_ftrace;char *arch_ftrace_match_adjust (char *str,const char *search); -#ifdef CONFIG_HAVE_FUNCTION_GRAPH_RETVAL -struct fgraph_ret_regs ; -unsigned long ftrace_return_to_handler (struct fgraph_ret_regs *ret_regs); +#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FREGS +unsigned long ftrace_return_to_handler (struct ftrace_regs *fregs);#else unsigned long ftrace_return_to_handler (unsigned long frame_pointer);#endif
@@ -134,6 +133,13 @@ extern int ftrace_enabled;* Also, architecture dependent fields can be used for internal process. * (e.g. orig_ax on x86_64) * +* Basically, ftrace_regs stores the registers related to the context. +* On function entry, registers for function parameters and hooking the +* function call are stored, and on function exit, registers for function +* return value and frame pointers are stored. +* +* And also, it dpends on the context that which registers are restored +* from the ftrace_regs. * On the function entry, those registers will be restored except for * the stack pointer, so that user can change the function parameters * and instruction pointer (e.g. live patching.)
include/linux/ftrace_regs.h +2 -0
@@ -30,6 +30,8 @@ struct ftrace_regs; override_function_with_return(&arch_ftrace_regs(fregs)->regs)#define ftrace_regs_query_register_offset (name) \ regs_query_register_offset(name) +#define ftrace_regs_get_frame_pointer (fregs) \ + frame_pointer(&arch_ftrace_regs(fregs)->regs)#endif /* HAVE_ARCH_FTRACE_REGS */
kernel/trace/Kconfig +2 -2
@@ -31,7 +31,7 @@ config HAVE_FUNCTION_GRAPH_TRACER help See Documentation/trace/ftrace-design.rst -config HAVE_FUNCTION_GRAPH_RETVAL +config HAVE_FUNCTION_GRAPH_FREGS bool config HAVE_DYNAMIC_FTRACE
@@ -232,7 +232,7 @@ config FUNCTION_GRAPH_TRACER config FUNCTION_GRAPH_RETVAL bool "Kernel Function Graph Return Value" - depends on HAVE_FUNCTION_GRAPH_RETVAL + depends on HAVE_FUNCTION_GRAPH_FREGS depends on FUNCTION_GRAPH_TRACER default n help
kernel/trace/fgraph.c +9 -12
@@ -793,15 +793,12 @@ static struct notifier_block ftrace_suspend_notifier = { .notifier_call = ftrace_suspend_notifier_call, }; -/* fgraph_ret_regs is not defined without CONFIG_FUNCTION_GRAPH_RETVAL */ -struct fgraph_ret_regs ; -/* * Send the trace to the ring-buffer. * @return the original return address. */ -static unsigned long __ftrace_return_to_handler (struct fgraph_ret_regs *ret_regs, -unsigned long frame_pointer) +static inline unsigned long +__ftrace_return_to_handler (struct ftrace_regs *fregs,unsigned long frame_pointer) {struct ftrace_ret_stack *ret_stack;struct ftrace_graph_ret trace;
@@ -821,7 +818,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs trace.rettime =trace_clock_local ();#ifdef CONFIG_FUNCTION_GRAPH_RETVAL - trace.retval =fgraph_ret_regs_return_value (ret_regs); + trace.retval =ftrace_regs_get_return_value (fregs);#endif bitmap =get_bitmap_bits (current, offset);
@@ -856,14 +853,14 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs }/* -* After all architecures have selected HAVE_FUNCTION_GRAPH_RETVAL, we can -* leave only ftrace_return_to_handler(ret_regs). +* After all architecures have selected HAVE_FUNCTION_GRAPH_FREGS, we can +* leave only ftrace_return_to_handler(fregs). */ -#ifdef CONFIG_HAVE_FUNCTION_GRAPH_RETVAL -unsigned long ftrace_return_to_handler (struct fgraph_ret_regs *ret_regs) +#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FREGS +unsigned long ftrace_return_to_handler (struct ftrace_regs *fregs) { -return __ftrace_return_to_handler (ret_regs, -fgraph_ret_regs_frame_pointer (ret_regs)); +return __ftrace_return_to_handler (fregs, +ftrace_regs_get_frame_pointer (fregs)); }#else unsigned long ftrace_return_to_handler (unsigned long frame_pointer)
Re: [PATCH v17 02/16] function_graph: Replace fgraph_ret_regs with ftrace_regs
Quoted 42 lines · Masami Hiramatsu (Google)
From: Masami Hiramatsu (Google) <[email protected]>
Use
ftrace_regsinstead offgraph_ret_regsfor tracing return value onfunction_graphtracer because of simplifying the callback interface.The
CONFIG_HAVE_FUNCTION_GRAPH_RETVALis also replaced byCONFIG_HAVE_FUNCTION_GRAPH_FREGS.Signed-off-by Masami Hiramatsu (Google) <[email protected]>Acked-by Heiko Carstens <[email protected]>Cc Catalin Marinas <[email protected]>Cc Will Deacon <[email protected]>Cc Steven Rostedt <[email protected]>Cc Mark Rutland <[email protected]>Cc Huacai Chen <[email protected]>Cc WANG Xuerui <[email protected]>Cc Paul Walmsley <[email protected]>Cc Palmer Dabbelt <[email protected]>Cc Albert Ou <[email protected]>Cc Vasily Gorbik <[email protected]>Cc Alexander Gordeev <[email protected]>Cc Heiko Carstens <[email protected]>Cc Christian Borntraeger <[email protected]>Cc Sven Schnelle <[email protected]>Cc Thomas Gleixner <[email protected]>Cc Ingo Molnar <[email protected]>Cc Borislav Petkov <[email protected]>Cc Dave Hansen <[email protected]>Cc "H. Peter Anvin" <[email protected]>Cc Mathieu Desnoyers <[email protected]>---
Changes in v17:
- Fixes s390return_to_handleraccording to Heiko's advice.
Changes in v16:
- According to the recentftrace_regs.hchange, overrideftrace_regs_get_frame_pointer()if needed.
- s390: keepstack_frameon stack, just replacefgraph_ret_regswithftrace_regs.
Changes in v8:
- Newly added.
Quoted 5 lines
--- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/ftrace.h | 23 ++++++----------------- arch/arm64/kernel/asm-offsets.c | 12 ------------ arch/arm64/kernel/entry-ftrace.S | 32 ++++++++++++++++++--------------
For the arm64 parts:
Will
Masami Hiramatsu (Google)
maintainerRe: [PATCH v17 02/16] function_graph: Replace fgraph_ret_regs with ftrace_regs
Quoted 49 lines · On Mon, 21 Oct 2024 17:46:58 +0100 Will Deacon <[email protected]> wrote:
Quoted 42 lines · Masami Hiramatsu (Google)
From: Masami Hiramatsu (Google) <[email protected]>
Use
ftrace_regsinstead offgraph_ret_regsfor tracing return value onfunction_graphtracer because of simplifying the callback interface.The
CONFIG_HAVE_FUNCTION_GRAPH_RETVALis also replaced byCONFIG_HAVE_FUNCTION_GRAPH_FREGS.Signed-off-by Masami Hiramatsu (Google) <[email protected]>Acked-by Heiko Carstens <[email protected]>Cc Catalin Marinas <[email protected]>Cc Will Deacon <[email protected]>Cc Steven Rostedt <[email protected]>Cc Mark Rutland <[email protected]>Cc Huacai Chen <[email protected]>Cc WANG Xuerui <[email protected]>Cc Paul Walmsley <[email protected]>Cc Palmer Dabbelt <[email protected]>Cc Albert Ou <[email protected]>Cc Vasily Gorbik <[email protected]>Cc Alexander Gordeev <[email protected]>Cc Heiko Carstens <[email protected]>Cc Christian Borntraeger <[email protected]>Cc Sven Schnelle <[email protected]>Cc Thomas Gleixner <[email protected]>Cc Ingo Molnar <[email protected]>Cc Borislav Petkov <[email protected]>Cc Dave Hansen <[email protected]>Cc "H. Peter Anvin" <[email protected]>Cc Mathieu Desnoyers <[email protected]>---
Changes in v17:
- Fixes s390return_to_handleraccording to Heiko's advice.
Changes in v16:
- According to the recentftrace_regs.hchange, overrideftrace_regs_get_frame_pointer()if needed.
- s390: keepstack_frameon stack, just replacefgraph_ret_regswithftrace_regs.
Changes in v8:
- Newly added.Quoted 5 lines
--- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/ftrace.h | 23 ++++++----------------- arch/arm64/kernel/asm-offsets.c | 12 ------------ arch/arm64/kernel/entry-ftrace.S | 32 ++++++++++++++++++--------------
Quoted 3 lines
For the arm64 parts:
Acked-by Will Deacon <[email protected]>
Thank you!
Quoted 2 lines
Will
Signature · 1 line
Masami Hiramatsu (Google) <[email protected]>
Masami Hiramatsu (Google)
maintainerPATCH v17 3/16 function_graph: Pass ftrace_regs to retfunc
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Pass ftrace_regs to the fgraph_ops::retfunc(). If ftrace_regs is not available, it passes a NULL instead. User callback function can access some registers (including return address) via this ftrace_regs.
---
Changes in v8:
- Pass ftrace_regs to retfunc, instead of adding retregfunc.
Changes in v6:
- update to use ftrace_regs_get_return_value() because of reordering patches.
Changes in v3:
- Update for new multiple fgraph.
- Save the return address to instruction pointer in ftrace_regs.
--- include/linux/ftrace.h | 3 ++- kernel/trace/fgraph.c | 16 +++++++++++----- kernel/trace/ftrace.c | 3 ++- kernel/trace/trace.h | 3 ++- kernel/trace/trace_functions_graph.c | 7 ++++--- kernel/trace/trace_irqsoff.c | 3 ++- kernel/trace/trace_sched_wakeup.c | 3 ++- kernel/trace/trace_selftest.c | 3 ++- 8 files changed, 27 insertions(+), 14 deletions(-)
include/linux/ftrace.h +2 -1
@@ -1075,7 +1075,8 @@ struct fgraph_ops;/* Type of the callback handlers for tracing function graph*/ typedef void (*trace_func_graph_ret_t )(struct ftrace_graph_ret *, -struct fgraph_ops *);/* return */ +struct fgraph_ops *, +struct ftrace_regs *);/* return */ typedef int (*trace_func_graph_ent_t )(struct ftrace_graph_ent *,struct fgraph_ops *,struct ftrace_regs *);/* entry */
kernel/trace/fgraph.c +11 -5
@@ -297,7 +297,8 @@ static int entry_run(struct ftrace_graph_ent *trace, struct fgraph_ops *ops, }/* ftrace_graph_return set to this to tell some archs to run function graph */ -static void return_run (struct ftrace_graph_ret *trace,struct fgraph_ops *ops) +static void return_run (struct ftrace_graph_ret *trace,struct fgraph_ops *ops, +struct ftrace_regs *fregs) { }
@@ -526,7 +527,8 @@ int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, }static void ftrace_graph_ret_stub (struct ftrace_graph_ret *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) { }
@@ -817,6 +819,9 @@ __ftrace_return_to_handler(struct ftrace_regs *fregs, unsigned long frame_pointe } trace.rettime =trace_clock_local (); +if (fregs) +ftrace_regs_set_instruction_pointer (fregs, ret); +#ifdef CONFIG_FUNCTION_GRAPH_RETVAL trace.retval =ftrace_regs_get_return_value (fregs);#endif
@@ -826,7 +831,7 @@ __ftrace_return_to_handler(struct ftrace_regs *fregs, unsigned long frame_pointe#ifdef CONFIG_HAVE_STATIC_CALL if (static_branch_likely (&fgraph_do_direct)) {if (test_bit (fgraph_direct_gops->idx, &bitmap)) -static_call (fgraph_retfunc)(&trace, fgraph_direct_gops); +static_call (fgraph_retfunc)(&trace, fgraph_direct_gops, fregs); } else#endif {
@@ -836,7 +841,7 @@ __ftrace_return_to_handler(struct ftrace_regs *fregs, unsigned long frame_pointeif (gops == &fgraph_stub)continue ; - gops->retfunc (&trace, gops); + gops->retfunc (&trace, gops, fregs); } }
@@ -1009,7 +1014,8 @@ void ftrace_graph_sleep_time_control(bool enable)* Simply points to ftrace_stub, but with the proper protocol. * Defined by the linker script in linux/vmlinux.lds.h */ -void ftrace_stub_graph (struct ftrace_graph_ret *trace,struct fgraph_ops *gops); +void ftrace_stub_graph (struct ftrace_graph_ret *trace,struct fgraph_ops *gops, +struct ftrace_regs *fregs);/* The callbacks that hook a function */ trace_func_graph_ret_t ftrace_graph_return = ftrace_stub_graph;
kernel/trace/ftrace.c +2 -1
@@ -850,7 +850,8 @@ static int profile_graph_entry(struct ftrace_graph_ent *trace, }static void profile_graph_return (struct ftrace_graph_ret *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) {struct profile_fgraph_data *profile_data;struct ftrace_profile_stat *stat;
kernel/trace/trace.h +2 -1
@@ -694,7 +694,8 @@ void trace_latency_header(struct seq_file *m);void trace_default_header (struct seq_file *m);void print_trace_header (struct seq_file *m,struct trace_iterator *iter); -void trace_graph_return (struct ftrace_graph_ret *trace,struct fgraph_ops *gops); +void trace_graph_return (struct ftrace_graph_ret *trace,struct fgraph_ops *gops, +struct ftrace_regs *fregs);int trace_graph_entry (struct ftrace_graph_ent *trace,struct fgraph_ops *gops,struct ftrace_regs *fregs);
kernel/trace/trace_functions_graph.c +4 -3
@@ -319,7 +319,7 @@ static void handle_nosleeptime(struct ftrace_graph_ret *trace, }void trace_graph_return (struct ftrace_graph_ret *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops,struct ftrace_regs *fregs) {unsigned long *task_var =fgraph_get_task_var (gops);struct trace_array *tr = gops->private;
@@ -359,7 +359,8 @@ void trace_graph_return(struct ftrace_graph_ret *trace, }static void trace_graph_thresh_return (struct ftrace_graph_ret *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) {struct fgraph_times *ftimes;int size;
@@ -383,7 +384,7 @@ static void trace_graph_thresh_return(struct ftrace_graph_ret *trace, (trace->rettime - ftimes->calltime < tracing_thresh)) return; else -trace_graph_return (trace ,gops ); +trace_graph_return (trace ,gops ,fregs ); }static struct fgraph_ops funcgraph_ops = {
kernel/trace/trace_irqsoff.c +2 -1
@@ -208,7 +208,8 @@ static int irqsoff_graph_entry(struct ftrace_graph_ent *trace, }static void irqsoff_graph_return (struct ftrace_graph_ret *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) {struct trace_array *tr = irqsoff_trace;struct trace_array_cpu *data;
kernel/trace/trace_sched_wakeup.c +2 -1
@@ -144,7 +144,8 @@ static int wakeup_graph_entry(struct ftrace_graph_ent *trace, }static void wakeup_graph_return (struct ftrace_graph_ret *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) {struct trace_array *tr = wakeup_trace;struct trace_array_cpu *data;
kernel/trace/trace_selftest.c +2 -1
@@ -808,7 +808,8 @@ static __init int store_entry(struct ftrace_graph_ent *trace, }static __init void store_return (struct ftrace_graph_ret *trace, -struct fgraph_ops *gops) +struct fgraph_ops *gops, +struct ftrace_regs *fregs) { struct fgraph_fixture *fixture = container_of(gops, struct fgraph_fixture, gops);const char *type = fixture->store_type_name;
Masami Hiramatsu (Google)
maintainerPATCH v17 4/16 fprobe: Use ftrace_regs in fprobe entry handler
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
This allows fprobes to be available with CONFIG_DYNAMIC_FTRACE_WITH_ARGS instead of CONFIG_DYNAMIC_FTRACE_WITH_REGS, then we can enable fprobe on arm64.
---
Changes in v6:
- Keep using SAVE_REGS flag to avoid breaking bpf kprobe-multi test.
--- include/linux/fprobe.h | 2 +- kernel/trace/Kconfig | 3 ++- kernel/trace/bpf_trace.c | 10 +++++++--- kernel/trace/fprobe.c | 3 ++- kernel/trace/trace_fprobe.c | 6 +++++- lib/test_fprobe.c | 4 ++-- samples/fprobe/fprobe_example.c | 2 +- 7 files changed, 20 insertions(+), 10 deletions(-)
include/linux/fprobe.h +1 -1
@@ -10,7 +10,7 @@struct fprobe ;typedef int (*fprobe_entry_cb )(struct fprobe *fp,unsigned long entry_ip, -unsigned long ret_ip,struct pt_regs *regs, +unsigned long ret_ip,struct ftrace_regs *regs,void *entry_data); typedef void (*fprobe_exit_cb)(struct fprobe *fp, unsigned long entry_ip,
kernel/trace/Kconfig +2 -1
@@ -297,7 +297,7 @@ config DYNAMIC_FTRACE_WITH_ARGS config FPROBE bool "Kernel Function Probe (fprobe)" depends on FUNCTION_TRACER - depends on DYNAMIC_FTRACE_WITH_REGS + depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS depends on HAVE_RETHOOK select RETHOOK default n
@@ -682,6 +682,7 @@ config FPROBE_EVENTS select TRACING select PROBE_EVENTS select DYNAMIC_EVENTS + depends on DYNAMIC_FTRACE_WITH_REGS default y help This allows user to add tracing events on the function entry and
kernel/trace/bpf_trace.c +7 -3
@@ -2517,7 +2517,7 @@ struct bpf_session_run_ctx {void *data; }; -#ifdef CONFIG_FPROBE +#if defined(CONFIG_FPROBE) && defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS) struct bpf_kprobe_multi_link { struct bpf_link link; struct fprobe fp;
@@ -2769,12 +2769,16 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,static int kprobe_multi_link_handler (struct fprobe *fp,unsigned long fentry_ip, -unsigned long ret_ip,struct pt_regs *regs, +unsigned long ret_ip,struct ftrace_regs *fregs,void *data) { +struct pt_regs *regs =ftrace_get_regs (fregs);struct bpf_kprobe_multi_link *link;int err; +if (!regs) +return 0 ; + link = container_of(fp, struct bpf_kprobe_multi_link, fp); err =kprobe_multi_link_prog_run (link,get_entry_ip (fentry_ip), regs, false, data);return is_kprobe_session (link->link.prog) ? err :0 ;
@@ -3049,7 +3053,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prkvfree (cookies); return err; } -#else /* !CONFIG_FPROBE */ +#else /* !CONFIG_FPROBE || !CONFIG_DYNAMIC_FTRACE_WITH_REGS */ int bpf_kprobe_multi_link_attach (const union bpf_attr *attr,struct bpf_prog *prog) {return -EOPNOTSUPP ;
kernel/trace/fprobe.c +2 -1
@@ -46,7 +46,7 @@ static inline void __fprobe_handler(unsigned long ip, unsigned long parent_ip, }if (fp->entry_handler) - ret = fp->entry_handler (fp, ip, parent_ip,ftrace_get_regs (fregs), entry_data); + ret = fp->entry_handler (fp, ip, parent_ip, fregs, entry_data);/* If entry_handler returns !0, nmissed is not counted. */ if (rh) {
@@ -182,6 +182,7 @@ static void fprobe_init(struct fprobe *fp) fp->ops.func = fprobe_kprobe_handler; else fp->ops.func = fprobe_handler; + fp->ops.flags |=FTRACE_OPS_FL_SAVE_REGS ; }
kernel/trace/trace_fprobe.c +5 -1
@@ -339,12 +339,16 @@ NOKPROBE_SYMBOL(fexit_perf_func);#endif /* CONFIG_PERF_EVENTS */ static int fentry_dispatcher (struct fprobe *fp,unsigned long entry_ip, -unsigned long ret_ip,struct pt_regs *regs, +unsigned long ret_ip,struct ftrace_regs *fregs,void *entry_data) { struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp); +struct pt_regs *regs =ftrace_get_regs (fregs);int ret =0 ; +if (!regs) +return 0 ; +if (trace_probe_test_flag (&tf->tp,TP_FLAG_TRACE ))fentry_trace_func (tf, entry_ip, regs);#ifdef CONFIG_PERF_EVENTS
lib/test_fprobe.c +2 -2
@@ -40,7 +40,7 @@ static noinline u32 fprobe_selftest_nest_target(u32 value, u32 (*nest)(u32)) static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip,unsigned long ret_ip, -struct pt_regs *regs,void *data) +struct ftrace_regs *fregs,void *data) {KUNIT_EXPECT_FALSE (current_test,preemptible ());/* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */
@@ -81,7 +81,7 @@ static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip,unsigned long ret_ip, -struct pt_regs *regs,void *data) +struct ftrace_regs *fregs,void *data) {KUNIT_EXPECT_FALSE (current_test,preemptible ());return 0 ;
samples/fprobe/fprobe_example.c +1 -1
@@ -50,7 +50,7 @@ static void show_backtrace(void)static int sample_entry_handler (struct fprobe *fp,unsigned long ip,unsigned long ret_ip, -struct pt_regs *regs,void *data) +struct ftrace_regs *fregs,void *data) {if (use_trace)/*
Masami Hiramatsu (Google)
maintainerPATCH v17 5/16 fprobe: Use ftrace_regs in fprobe exit handler
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Change the fprobe exit handler to use ftrace_regs structure instead of pt_regs. This also introduce HAVE_FTRACE_REGS_HAVING_PT_REGS which means the ftrace_regs is including the pt_regs so that ftrace_regs can provide pt_regs without memory allocation.
Fprobe introduces a new dependency with that.
---
Changes in v16:
- Rename HAVE_PT_REGS_TO_FTRACE_REGS_CAST to HAVE_FTRACE_REGS_HAVING_PT_REGS.
Changes in v3:
- Use ftrace_regs_get_return_value()
Changes from previous series: NOTHING, just forward ported.
--- arch/loongarch/Kconfig | 1 + arch/s390/Kconfig | 1 + arch/x86/Kconfig | 1 + include/linux/fprobe.h | 2 +- include/linux/ftrace.h | 6 ++++++ kernel/trace/Kconfig | 7 +++++++ kernel/trace/bpf_trace.c | 6 +++++- kernel/trace/fprobe.c | 3 ++- kernel/trace/trace_fprobe.c | 6 +++++- lib/test_fprobe.c | 6 +++--- samples/fprobe/fprobe_example.c | 2 +- 11 files changed, 33 insertions(+), 8 deletions(-)
arch/loongarch/Kconfig +1 -0
@@ -126,6 +126,7 @@ config LOONGARCH select HAVE_DMA_CONTIGUOUS select HAVE_DYNAMIC_FTRACE select HAVE_DYNAMIC_FTRACE_WITH_ARGS + select HAVE_FTRACE_REGS_HAVING_PT_REGS select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS select HAVE_DYNAMIC_FTRACE_WITH_REGS select HAVE_EBPF_JIT
arch/s390/Kconfig +1 -0
@@ -175,6 +175,7 @@ config S390 select HAVE_DMA_CONTIGUOUS select HAVE_DYNAMIC_FTRACE select HAVE_DYNAMIC_FTRACE_WITH_ARGS + select HAVE_FTRACE_REGS_HAVING_PT_REGS select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS select HAVE_DYNAMIC_FTRACE_WITH_REGS select HAVE_EBPF_JIT if HAVE_MARCH_Z196_FEATURES
arch/x86/Kconfig +1 -0
@@ -222,6 +222,7 @@ config X86 select HAVE_DYNAMIC_FTRACE select HAVE_DYNAMIC_FTRACE_WITH_REGS select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64 + select HAVE_FTRACE_REGS_HAVING_PT_REGS if X86_64 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS select HAVE_SAMPLE_FTRACE_DIRECT if X86_64 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
include/linux/fprobe.h +1 -1
@@ -14,7 +14,7 @@ typedef int (*fprobe_entry_cb)(struct fprobe *fp, unsigned long entry_ip, void *entry_data);typedef void (*fprobe_exit_cb )(struct fprobe *fp,unsigned long entry_ip, -unsigned long ret_ip,struct pt_regs *regs, +unsigned long ret_ip,struct ftrace_regs *regs,void *entry_data);/**
include/linux/ftrace.h +6 -0
@@ -176,6 +176,12 @@ static inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *fregs)#define ftrace_regs_set_instruction_pointer (fregs, ip) do { } while (0)#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */ +#ifdef CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS + +static_assert (sizeof (struct pt_regs ) ==ftrace_regs_size ()); + +#endif /* CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS */ + static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs) {if (!fregs)
kernel/trace/Kconfig +7 -0
@@ -57,6 +57,12 @@ config HAVE_DYNAMIC_FTRACE_WITH_ARGS This allows for use of ftrace_regs_get_argument() and ftrace_regs_get_stack_pointer(). +config HAVE_FTRACE_REGS_HAVING_PT_REGS + bool + help + If this is set, ftrace_regs has pt_regs, thus it can convert to + pt_regs without allocating memory. + config HAVE_DYNAMIC_FTRACE_NO_PATCHABLE bool help
@@ -298,6 +304,7 @@ config FPROBE bool "Kernel Function Probe (fprobe)" depends on FUNCTION_TRACER depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS + depends on HAVE_FTRACE_REGS_HAVING_PT_REGS || !HAVE_DYNAMIC_FTRACE_WITH_ARGS depends on HAVE_RETHOOK select RETHOOK default n
kernel/trace/bpf_trace.c +5 -1
@@ -2786,10 +2786,14 @@ kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,static void kprobe_multi_link_exit_handler (struct fprobe *fp,unsigned long fentry_ip, -unsigned long ret_ip,struct pt_regs *regs, +unsigned long ret_ip,struct ftrace_regs *fregs,void *data) {struct bpf_kprobe_multi_link *link; +struct pt_regs *regs =ftrace_get_regs (fregs); + +if (!regs) +return ; link = container_of(fp, struct bpf_kprobe_multi_link, fp);kprobe_multi_link_prog_run (link,get_entry_ip (fentry_ip), regs, true, data);
kernel/trace/fprobe.c +2 -1
@@ -124,6 +124,7 @@ static void fprobe_exit_handler(struct rethook_node *rh, void *data, {struct fprobe *fp = (struct fprobe *)data;struct fprobe_rethook_node *fpr; +struct ftrace_regs *fregs = (struct ftrace_regs *)regs;int bit;if (!fp ||fprobe_disabled (fp))
@@ -141,7 +142,7 @@ static void fprobe_exit_handler(struct rethook_node *rh, void *data,return ; } - fp->exit_handler (fp, fpr->entry_ip, ret_ip, regs, + fp->exit_handler (fp, fpr->entry_ip, ret_ip, fregs, fp->entry_data_size ? (void *)fpr->data :NULL );ftrace_test_recursion_unlock (bit); }
kernel/trace/trace_fprobe.c +5 -1
@@ -360,10 +360,14 @@ static int fentry_dispatcher(struct fprobe *fp, unsigned long entry_ip,NOKPROBE_SYMBOL (fentry_dispatcher);static void fexit_dispatcher (struct fprobe *fp,unsigned long entry_ip, -unsigned long ret_ip,struct pt_regs *regs, +unsigned long ret_ip,struct ftrace_regs *fregs,void *entry_data) { struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp); +struct pt_regs *regs =ftrace_get_regs (fregs); + +if (!regs) +return ;if (trace_probe_test_flag (&tf->tp,TP_FLAG_TRACE ))fexit_trace_func (tf, entry_ip, ret_ip, regs, entry_data);
lib/test_fprobe.c +3 -3
@@ -59,9 +59,9 @@ static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip, static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,unsigned long ret_ip, -struct pt_regs *regs,void *data) +struct ftrace_regs *fregs,void *data) { -unsigned long ret =regs_return_value (regs); +unsigned long ret =ftrace_regs_get_return_value (fregs);KUNIT_EXPECT_FALSE (current_test,preemptible ());if (ip != target_ip) {
@@ -89,7 +89,7 @@ static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip, static notrace void nest_exit_handler(struct fprobe *fp, unsigned long ip,unsigned long ret_ip, -struct pt_regs *regs,void *data) +struct ftrace_regs *fregs,void *data) {KUNIT_EXPECT_FALSE (current_test,preemptible ());KUNIT_EXPECT_EQ (current_test, ip, target_nest_ip);
samples/fprobe/fprobe_example.c +1 -1
@@ -67,7 +67,7 @@ static int sample_entry_handler(struct fprobe *fp, unsigned long ip, }static void sample_exit_handler (struct fprobe *fp,unsigned long ip, -unsigned long ret_ip,struct pt_regs *regs, +unsigned long ret_ip,struct ftrace_regs *regs,void *data) {unsigned long rip = ret_ip;
Masami Hiramatsu (Google)
maintainerPATCH v17 6/16 tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Add ftrace_partial_regs() which converts the ftrace_regs to pt_regs. This is for the eBPF which needs this to keep the same pt_regs interface to access registers.
Thus when replacing the pt_regs with ftrace_regs in fprobes (which is used by kprobe_multi eBPF event), this will be used.
If the architecture defines its own ftrace_regs, this copies partial registers to pt_regs and returns it. If not, ftrace_regs is the same as pt_regs and ftrace_partial_regs() will return ftrace_regs::regs.
---
Changes in v14:
- Add riscv change.
Changes in v8:
- Add the reason why this required in changelog.
Changes from previous series: NOTHING, just forward ported.
--- arch/arm64/include/asm/ftrace.h | 11 +++++++++++ arch/riscv/include/asm/ftrace.h | 14 ++++++++++++++ include/linux/ftrace.h | 17 +++++++++++++++++ 3 files changed, 42 insertions(+)
arch/arm64/include/asm/ftrace.h +11 -0
@@ -135,6 +135,17 @@ ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs)return arch_ftrace_regs (fregs)->fp; } +static __always_inline struct pt_regs * +ftrace_partial_regs (const struct ftrace_regs *fregs,struct pt_regs *regs) +{ +memcpy (regs->regs,arch_ftrace_regs (fregs)->regs,sizeof (u64) *9 ); + regs->sp =arch_ftrace_regs (fregs)->sp; + regs->pc =arch_ftrace_regs (fregs)->pc; + regs->regs[29 ] =arch_ftrace_regs (fregs)->fp; + regs->regs[30 ] =arch_ftrace_regs (fregs)->lr; +return regs; +} +int ftrace_regs_query_register_offset (const char *name);int ftrace_init_nop (struct module *mod,struct dyn_ftrace *rec);
arch/riscv/include/asm/ftrace.h +14 -0
@@ -197,6 +197,20 @@ static __always_inline void ftrace_override_function_with_return(struct ftrace_rarch_ftrace_regs (fregs)->epc =arch_ftrace_regs (fregs)->ra; } +static __always_inline struct pt_regs * +ftrace_partial_regs (const struct ftrace_regs *fregs,struct pt_regs *regs) +{ +struct __arch_ftrace_regs *afregs =arch_ftrace_regs (fregs); + +memcpy (®s->a0, afregs->args,sizeof (u64) *8 ); + regs->epc = afregs->epc; + regs->ra = afregs->ra; + regs->sp = afregs->sp; + regs->s0 = afregs->s0; + regs->t1 = afregs->t1; +return regs; +} +int ftrace_regs_query_register_offset (const char *name); void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
include/linux/ftrace.h +17 -0
@@ -190,6 +190,23 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregsreturn arch_ftrace_get_regs (fregs); } +#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS ) || \ + defined(CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS ) + +static __always_inline struct pt_regs * +ftrace_partial_regs (struct ftrace_regs *fregs,struct pt_regs *regs) +{ +/* +* If CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS=y, ftrace_regs memory +* layout is including pt_regs. So always returns that address. +* Since arch_ftrace_get_regs() will check some members and may return +* NULL, we can not use it. +*/ +return &arch_ftrace_regs (fregs)->regs; +} + +#endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS */ +/* * When true, the ftrace_regs_{get,set}_*() functions may be used on fregs. * Note: this can be true even when ftrace_get_regs() cannot provide a pt_regs.
Will Deacon
maintainerRe: [PATCH v17 06/16] tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs
Quoted 39 lines · Masami Hiramatsu (Google)
From: Masami Hiramatsu (Google) <[email protected]>
Add
ftrace_partial_regs()which converts theftrace_regstopt_regs. This is for the eBPF which needs this to keep the samept_regsinterface to access registers.
Thus when replacing thept_regswithftrace_regsin fprobes (which is used bykprobe_multieBPF event), this will be used.If the architecture defines its own
ftrace_regs, this copies partial registers topt_regsand returns it. If not,ftrace_regsis the same aspt_regsandftrace_partial_regs()will returnftrace_regs::regs.Signed-off-by Masami Hiramatsu (Google) <[email protected]>Acked-by Florent Revest <[email protected]>Cc Steven Rostedt <[email protected]>Cc Mark Rutland <[email protected]>Cc Catalin Marinas <[email protected]>Cc Will Deacon <[email protected]>Cc Paul Walmsley <[email protected]>Cc Palmer Dabbelt <[email protected]>Cc Albert Ou <[email protected]>---
Changes in v14:
- Add riscv change.
Changes in v8:
- Add the reason why this required in changelog.
Changes from previous series: NOTHING, just forward ported.--- arch/arm64/include/asm/ftrace.h | 11 +++++++++++ arch/riscv/include/asm/ftrace.h | 14 ++++++++++++++ include/linux/ftrace.h | 17 +++++++++++++++++ 3 files changed, 42 insertions(+)arch/arm64/include/asm/ftrace.h +0
-0
arch/arm64/include/asm/ftrace.h ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs) · line 141
Quoted 7 lines
arch/arm64/include/asm/ftrace.h +4
-0@@ -135,6 +135,17 @@ ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs)return arch_ftrace_regs (fregs)->fp; } +static __always_inline struct pt_regs * +ftrace_partial_regs (const struct ftrace_regs *fregs,struct pt_regs *regs) +{ +memcpy (regs->regs,arch_ftrace_regs (fregs)->regs,sizeof (u64) *9 );
Since ftrace_regs::regs is an 'unsigned long regs[9]' can we just use sizeof() on that instead of hard-coding the length of the array here?
Will
Masami Hiramatsu (Google)
maintainerRe: [PATCH v17 06/16] tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs
Quoted 43 lines · On Mon, 21 Oct 2024 17:46:19 +0100 Will Deacon <[email protected]> wrote:
Quoted 42 lines · Masami Hiramatsu (Google)
From: Masami Hiramatsu (Google) <[email protected]>
Add
ftrace_partial_regs()which converts theftrace_regstopt_regs. This is for the eBPF which needs this to keep the samept_regsinterface to access registers.
Thus when replacing thept_regswithftrace_regsin fprobes (which is used bykprobe_multieBPF event), this will be used.If the architecture defines its own
ftrace_regs, this copies partial registers topt_regsand returns it. If not,ftrace_regsis the same aspt_regsandftrace_partial_regs()will returnftrace_regs::regs.Signed-off-by Masami Hiramatsu (Google) <[email protected]>Acked-by Florent Revest <[email protected]>Cc Steven Rostedt <[email protected]>Cc Mark Rutland <[email protected]>Cc Catalin Marinas <[email protected]>Cc Will Deacon <[email protected]>Cc Paul Walmsley <[email protected]>Cc Palmer Dabbelt <[email protected]>Cc Albert Ou <[email protected]>---
Changes in v14:
- Add riscv change.
Changes in v8:
- Add the reason why this required in changelog.
Changes from previous series: NOTHING, just forward ported.--- arch/arm64/include/asm/ftrace.h | 11 +++++++++++ arch/riscv/include/asm/ftrace.h | 14 ++++++++++++++ include/linux/ftrace.h | 17 +++++++++++++++++ 3 files changed, 42 insertions(+)arch/arm64/include/asm/ftrace.h +0
-0@@ -135,6 +135,17 @@ ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs)return arch_ftrace_regs (fregs)->fp; }
Quoted 7 lines
arch/arm64/include/asm/ftrace.h ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs) · line 141
Quoted 4 lines
arch/arm64/include/asm/ftrace.h +4
-0+static __always_inline struct pt_regs * +ftrace_partial_regs (const struct ftrace_regs *fregs,struct pt_regs *regs) +{ +memcpy (regs->regs,arch_ftrace_regs (fregs)->regs,sizeof (u64) *9 );Since
ftrace_regs::regsis an 'unsigned long regs[9]' can we just usesizeof()on that instead of hard-coding the length of the array here?
Good catch! I will update it.
Thank you!
Quoted 2 lines
Will
Signature · 1 line
Masami Hiramatsu (Google) <[email protected]>
Masami Hiramatsu (Google)
maintainerPATCH v17 7/16 tracing: Add ftrace_fill_perf_regs() for perf event
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Add ftrace_fill_perf_regs() which should be compatible with the perf_fetch_caller_regs(). In other words, the pt_regs returned from the ftrace_fill_perf_regs() must satisfy 'user_mode(regs) == false' and can be used for stack tracing.
---
Changes in v16:
- Fix s390 to clear psw.mask according to Heiko's suggestion.
--- arch/arm64/include/asm/ftrace.h | 7 +++++++ arch/powerpc/include/asm/ftrace.h | 7 +++++++ arch/s390/include/asm/ftrace.h | 6 ++++++ arch/x86/include/asm/ftrace.h | 7 +++++++ include/linux/ftrace.h | 31 +++++++++++++++++++++++++++++++ 5 files changed, 58 insertions(+)
arch/arm64/include/asm/ftrace.h +7 -0
@@ -146,6 +146,13 @@ ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)return regs; } +#define arch_ftrace_fill_perf_regs (fregs, _regs) do { \ + (_regs)->pc = arch_ftrace_regs(fregs)->pc; \ + (_regs)->regs[29] = arch_ftrace_regs(fregs)->fp; \ + (_regs)->sp = arch_ftrace_regs(fregs)->sp; \ + (_regs)->pstate = PSR_MODE_EL1h; \ + } while (0) +int ftrace_regs_query_register_offset (const char *name);int ftrace_init_nop (struct module *mod,struct dyn_ftrace *rec);
arch/powerpc/include/asm/ftrace.h +7 -0
@@ -40,6 +40,13 @@ static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *return arch_ftrace_regs (fregs)->regs.msr ? &arch_ftrace_regs (fregs)->regs :NULL ; } +#define arch_ftrace_fill_perf_regs (fregs, _regs) do { \ + (_regs)->result = 0; \ + (_regs)->nip = arch_ftrace_regs(fregs)->regs.nip; \ + (_regs)->gpr[1] = arch_ftrace_regs(fregs)->regs.gpr[1]; \ + asm volatile("mfmsr %0" : "=r" ((_regs)->msr)); \ + } while (0) + static __always_inline voidftrace_regs_set_instruction_pointer (struct ftrace_regs *fregs,unsigned long ip)
arch/s390/include/asm/ftrace.h +6 -0
@@ -76,6 +76,12 @@ ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs)return ftrace_regs_get_stack_pointer (fregs); } +#define arch_ftrace_fill_perf_regs (fregs, _regs) do { \ + (_regs)->psw.mask = 0; \ + (_regs)->psw.addr = arch_ftrace_regs(fregs)->regs.psw.addr; \ + (_regs)->gprs[15] = arch_ftrace_regs(fregs)->regs.gprs[15]; \ + } while (0) +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS /* * When an ftrace registered caller is tracing a function that is
arch/x86/include/asm/ftrace.h +7 -0
@@ -45,6 +45,13 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs)return &arch_ftrace_regs (fregs)->regs; } +#define arch_ftrace_fill_perf_regs (fregs, _regs) do { \ + (_regs)->ip = arch_ftrace_regs(fregs)->regs.ip; \ + (_regs)->sp = arch_ftrace_regs(fregs)->regs.sp; \ + (_regs)->cs = __KERNEL_CS; \ + (_regs)->flags = 0; \ + } while (0) +#define ftrace_regs_set_instruction_pointer (fregs, _ip) \ do { arch_ftrace_regs(fregs)->regs.ip = (_ip); } while (0)
include/linux/ftrace.h +31 -0
@@ -207,6 +207,37 @@ ftrace_partial_regs(struct ftrace_regs *fregs, struct pt_regs *regs)#endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS */ +#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS + +/* +* Please define arch dependent pt_regs which compatible to the +* perf_arch_fetch_caller_regs() but based on ftrace_regs. +* This requires +* - user_mode(_regs) returns false (always kernel mode). +* - able to use the _regs for stack trace. +*/ +#ifndef arch_ftrace_fill_perf_regs +/* As same as perf_arch_fetch_caller_regs(), do nothing by default */ +#define arch_ftrace_fill_perf_regs (fregs, _regs) do {} while (0) +#endif + +static __always_inline struct pt_regs * +ftrace_fill_perf_regs (struct ftrace_regs *fregs,struct pt_regs *regs) +{ +arch_ftrace_fill_perf_regs (fregs, regs); +return regs; +} + +#else /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */ + +static __always_inline struct pt_regs * +ftrace_fill_perf_regs (struct ftrace_regs *fregs,struct pt_regs *regs) +{ +return &arch_ftrace_regs (fregs)->regs; +} + +#endif +/* * When true, the ftrace_regs_{get,set}_*() functions may be used on fregs. * Note: this can be true even when ftrace_get_regs() cannot provide a pt_regs.
Re: [PATCH v17 07/16] tracing: Add ftrace_fill_perf_regs() for perf event
Quoted 45 lines · Masami Hiramatsu (Google)
From: Masami Hiramatsu (Google) <[email protected]>
Add
ftrace_fill_perf_regs()which should be compatible with theperf_fetch_caller_regs(). In other words, thept_regsreturned from theftrace_fill_perf_regs()must satisfy 'user_mode(regs)== false' and can be used for stack tracing.Signed-off-by Masami Hiramatsu (Google) <[email protected]>Cc Steven Rostedt <[email protected]>Cc Mark Rutland <[email protected]>Cc Catalin Marinas <[email protected]>Cc Will Deacon <[email protected]>Cc Michael Ellerman <[email protected]>Cc Nicholas Piggin <[email protected]>Cc Christophe Leroy <[email protected]>Cc Naveen N Rao <[email protected]>Cc Madhavan Srinivasan <[email protected]>Cc Heiko Carstens <[email protected]>Cc Vasily Gorbik <[email protected]>Cc Alexander Gordeev <[email protected]>Cc Christian Borntraeger <[email protected]>Cc Sven Schnelle <[email protected]>Cc Thomas Gleixner <[email protected]>Cc Ingo Molnar <[email protected]>Cc Borislav Petkov <[email protected]>Cc Dave Hansen <[email protected]>Cc "H. Peter Anvin" <[email protected]>---
Changes in v16:
- Fix s390 to clear psw.mask according to Heiko's suggestion.--- arch/arm64/include/asm/ftrace.h | 7 +++++++ arch/powerpc/include/asm/ftrace.h | 7 +++++++ arch/s390/include/asm/ftrace.h | 6 ++++++ arch/x86/include/asm/ftrace.h | 7 +++++++ include/linux/ftrace.h | 31 +++++++++++++++++++++++++++++++ 5 files changed, 58 insertions(+)arch/arm64/include/asm/ftrace.h +0
-0
arch/arm64/include/asm/ftrace.h ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs) · line 154
Quoted 9 lines
arch/arm64/include/asm/ftrace.h +6
-0@@ -146,6 +146,13 @@ ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)return regs; } +#define arch_ftrace_fill_perf_regs (fregs, _regs) do { \ + (_regs)->pc = arch_ftrace_regs(fregs)->pc; \ + (_regs)->regs[29] = arch_ftrace_regs(fregs)->fp; \ + (_regs)->sp = arch_ftrace_regs(fregs)->sp; \ + (_regs)->pstate = PSR_MODE_EL1h; \ + } while (0)
arm64 bit looks correct to me:
Will
Masami Hiramatsu (Google)
maintainerRe: [PATCH v17 07/16] tracing: Add ftrace_fill_perf_regs() for perf event
Quoted 58 lines · On Mon, 21 Oct 2024 18:01:21 +0100 Will Deacon <[email protected]> wrote:
Quoted 45 lines · Masami Hiramatsu (Google)
From: Masami Hiramatsu (Google) <[email protected]>
Add
ftrace_fill_perf_regs()which should be compatible with theperf_fetch_caller_regs(). In other words, thept_regsreturned from theftrace_fill_perf_regs()must satisfy 'user_mode(regs)== false' and can be used for stack tracing.Signed-off-by Masami Hiramatsu (Google) <[email protected]>Cc Steven Rostedt <[email protected]>Cc Mark Rutland <[email protected]>Cc Catalin Marinas <[email protected]>Cc Will Deacon <[email protected]>Cc Michael Ellerman <[email protected]>Cc Nicholas Piggin <[email protected]>Cc Christophe Leroy <[email protected]>Cc Naveen N Rao <[email protected]>Cc Madhavan Srinivasan <[email protected]>Cc Heiko Carstens <[email protected]>Cc Vasily Gorbik <[email protected]>Cc Alexander Gordeev <[email protected]>Cc Christian Borntraeger <[email protected]>Cc Sven Schnelle <[email protected]>Cc Thomas Gleixner <[email protected]>Cc Ingo Molnar <[email protected]>Cc Borislav Petkov <[email protected]>Cc Dave Hansen <[email protected]>Cc "H. Peter Anvin" <[email protected]>---
Changes in v16:
- Fix s390 to clear psw.mask according to Heiko's suggestion.--- arch/arm64/include/asm/ftrace.h | 7 +++++++ arch/powerpc/include/asm/ftrace.h | 7 +++++++ arch/s390/include/asm/ftrace.h | 6 ++++++ arch/x86/include/asm/ftrace.h | 7 +++++++ include/linux/ftrace.h | 31 +++++++++++++++++++++++++++++++ 5 files changed, 58 insertions(+)arch/arm64/include/asm/ftrace.h +0
-0arch/arm64/include/asm/ftrace.h ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs) · line 154
Quoted 9 lines
arch/arm64/include/asm/ftrace.h +6
-0@@ -146,6 +146,13 @@ ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)return regs; } +#define arch_ftrace_fill_perf_regs (fregs, _regs) do { \ + (_regs)->pc = arch_ftrace_regs(fregs)->pc; \ + (_regs)->regs[29] = arch_ftrace_regs(fregs)->fp; \ + (_regs)->sp = arch_ftrace_regs(fregs)->sp; \ + (_regs)->pstate = PSR_MODE_EL1h; \ + } while (0)arm64 bit looks correct to me:
Quoted 1 line
Acked-by Will Deacon <[email protected]>
Thank you!
Quoted 2 lines
Will
Signature · 1 line
Masami Hiramatsu (Google) <[email protected]>
Masami Hiramatsu (Google)
maintainerPATCH v17 8/16 tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Allow fprobe events to be enabled with CONFIG_DYNAMIC_FTRACE_WITH_ARGS. With this change, fprobe events mostly use ftrace_regs instead of pt_regs. Note that if the arch doesn't enable HAVE_FTRACE_REGS_HAVING_PT_REGS, fprobe events will not be able to be used from perf.
---
Changes in v9:
- Copy store_trace_entry_data() as store_fprobe_entry_data() for fprobe.
Chagnes in v3:
- Use ftrace_regs_get_return_value().
Changes in v2:
- Define ftrace_regs_get_kernel_stack_nth() for !CONFIG_HAVE_REGS_AND_STACK_ACCESS_API.
Changes from previous series: Update against the new series.
--- include/linux/ftrace.h | 17 ++++++ kernel/trace/Kconfig | 1 kernel/trace/trace_fprobe.c | 107 +++++++++++++++++++++++++-------------- kernel/trace/trace_probe_tmpl.h | 2 - 4 files changed, 86 insertions(+), 41 deletions(-)
include/linux/ftrace.h +17 -0
@@ -250,6 +250,23 @@ static __always_inline bool ftrace_regs_has_args(struct ftrace_regs *fregs)return ftrace_get_regs (fregs) !=NULL ; } +#ifdef CONFIG_HAVE_REGS_AND_STACK_ACCESS_API +static __always_inline unsigned long +ftrace_regs_get_kernel_stack_nth (struct ftrace_regs *fregs,unsigned int nth) +{ +unsigned long *stackp; + + stackp = (unsigned long *)ftrace_regs_get_stack_pointer (fregs); +if (((unsigned long )(stackp + nth) & ~(THREAD_SIZE -1 )) == + ((unsigned long )stackp & ~(THREAD_SIZE -1 ))) +return *(stackp + nth); + +return 0 ; +} +#else /* !CONFIG_HAVE_REGS_AND_STACK_ACCESS_API */ +#define ftrace_regs_get_kernel_stack_nth (fregs, nth) (0L) +#endif /* CONFIG_HAVE_REGS_AND_STACK_ACCESS_API */ +typedef void (*ftrace_func_t )(unsigned long ip,unsigned long parent_ip,struct ftrace_ops *op,struct ftrace_regs *fregs);
kernel/trace/Kconfig +0 -1
@@ -689,7 +689,6 @@ config FPROBE_EVENTS select TRACING select PROBE_EVENTS select DYNAMIC_EVENTS - depends on DYNAMIC_FTRACE_WITH_REGS default y help This allows user to add tracing events on the function entry and
kernel/trace/trace_fprobe.c +68 -39
271 lines not on this page · raw message
kernel/trace/trace_probe_tmpl.h +1 -1
@@ -232,7 +232,7 @@ process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,/* Sum up total data length for dynamic arrays (strings) */ static nokprobe_inline int -__get_data_size (struct trace_probe *tp,struct pt_regs *regs,void *edata) +__get_data_size (struct trace_probe *tp,void *regs,void *edata) {struct probe_arg *arg;int i, len, ret =0 ;
Masami Hiramatsu (Google)
maintainerPATCH v17 9/16 bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Enable kprobe_multi feature if CONFIG_FPROBE is enabled. The pt_regs is converted from ftrace_regs by ftrace_partial_regs(), thus some registers may always returns 0. But it should be enough for function entry (access arguments) and exit (access return value).
---
Changes in v9:
- Avoid wasting memory for bpf_kprobe_multi_pt_regs when CONFIG_HAVE_PT_REGS_TO_FTRACE_REGS_CAST=y
--- kernel/trace/bpf_trace.c | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-)
kernel/trace/bpf_trace.c +14 -13
@@ -2517,7 +2517,7 @@ struct bpf_session_run_ctx {void *data; }; -#if defined(CONFIG_FPROBE) && defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS) +#ifdef CONFIG_FPROBE struct bpf_kprobe_multi_link { struct bpf_link link; struct fprobe fp;
@@ -2540,6 +2540,13 @@ struct user_syms {char *buf; }; +#ifndef CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS +static DEFINE_PER_CPU(struct pt_regs, bpf_kprobe_multi_pt_regs); +#define bpf_kprobe_multi_pt_regs_ptr () this_cpu_ptr(&bpf_kprobe_multi_pt_regs) +#else +#define bpf_kprobe_multi_pt_regs_ptr () (NULL) +#endif +static int copy_user_syms (struct user_syms *us,unsigned long __user *usyms,u32 cnt) {unsigned long __user usymbol;
@@ -2734,7 +2741,7 @@ static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx)static int kprobe_multi_link_prog_run (struct bpf_kprobe_multi_link *link, -unsigned long entry_ip,struct pt_regs *regs, +unsigned long entry_ip,struct ftrace_regs *fregs,bool is_return,void *data) {struct bpf_kprobe_multi_run_ctx run_ctx = {
@@ -2746,6 +2753,7 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, .entry_ip = entry_ip, };struct bpf_run_ctx *old_run_ctx; +struct pt_regs *regs;int err;if (unlikely (__this_cpu_inc_return (bpf_prog_active) !=1 )) {
@@ -2756,6 +2764,7 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,migrate_disable ();rcu_read_lock (); + regs =ftrace_partial_regs (fregs,bpf_kprobe_multi_pt_regs_ptr ()); old_run_ctx =bpf_set_run_ctx (&run_ctx.session_ctx.run_ctx); err =bpf_prog_run (link->link.prog, regs);bpf_reset_run_ctx (old_run_ctx);
@@ -2772,15 +2781,11 @@ kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip, unsigned long ret_ip, struct ftrace_regs *fregs, void *data) { - struct pt_regs *regs = ftrace_get_regs(fregs); struct bpf_kprobe_multi_link *link;int err; -if (!regs) -return 0 ; - link = container_of(fp, struct bpf_kprobe_multi_link, fp); - err =kprobe_multi_link_prog_run (link,get_entry_ip (fentry_ip), regs, false, data); + err =kprobe_multi_link_prog_run (link,get_entry_ip (fentry_ip), fregs, false, data);return is_kprobe_session (link->link.prog) ? err :0 ; }
@@ -2790,13 +2795,9 @@ kprobe_multi_link_exit_handler(struct fprobe *fp, unsigned long fentry_ip, void *data) {struct bpf_kprobe_multi_link *link; -struct pt_regs *regs =ftrace_get_regs (fregs); - -if (!regs) -return ; link = container_of(fp, struct bpf_kprobe_multi_link, fp); -kprobe_multi_link_prog_run (link,get_entry_ip (fentry_ip), regs, true, data); +kprobe_multi_link_prog_run (link,get_entry_ip (fentry_ip), fregs, true, data); }static int symbols_cmp_r (const void *a,const void *b,const void *priv)
@@ -3057,7 +3058,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prkvfree (cookies); return err; } -#else /* !CONFIG_FPROBE || !CONFIG_DYNAMIC_FTRACE_WITH_REGS */ +#else /* !CONFIG_FPROBE */ int bpf_kprobe_multi_link_attach (const union bpf_attr *attr,struct bpf_prog *prog) {return -EOPNOTSUPP ;
Masami Hiramatsu (Google)
maintainerPATCH v17 10/16 ftrace: Add CONFIG_HAVE_FTRACE_GRAPH_FUNC
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Add CONFIG_HAVE_FTRACE_GRAPH_FUNC kconfig in addition to ftrace_graph_func macro check. This is for the other feature (e.g. FPROBE) which requires to access ftrace_regs from fgraph_ops::entryfunc() can avoid compiling if the fgraph can not pass the valid ftrace_regs.
---
Changes in v8:
- Newly added.
--- arch/arm64/Kconfig | 1 + arch/loongarch/Kconfig | 1 + arch/powerpc/Kconfig | 1 + arch/riscv/Kconfig | 1 + arch/x86/Kconfig | 1 + kernel/trace/Kconfig | 5 +++++ 6 files changed, 10 insertions(+)
arch/arm64/Kconfig +1 -0
@@ -212,6 +212,7 @@ config ARM64 select HAVE_SAMPLE_FTRACE_DIRECT_MULTI select HAVE_EFFICIENT_UNALIGNED_ACCESS select HAVE_GUP_FAST + select HAVE_FTRACE_GRAPH_FUNC select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FUNCTION_TRACER select HAVE_FUNCTION_ERROR_INJECTION
arch/loongarch/Kconfig +1 -0
@@ -133,6 +133,7 @@ config LOONGARCH select HAVE_EFFICIENT_UNALIGNED_ACCESS if !ARCH_STRICT_ALIGN select HAVE_EXIT_THREAD select HAVE_GUP_FAST + select HAVE_FTRACE_GRAPH_FUNC select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FUNCTION_ARG_ACCESS_API select HAVE_FUNCTION_ERROR_INJECTION
arch/powerpc/Kconfig +1 -0
@@ -238,6 +238,7 @@ config PPC select HAVE_EBPF_JIT select HAVE_EFFICIENT_UNALIGNED_ACCESS select HAVE_GUP_FAST + select HAVE_FTRACE_GRAPH_FUNC select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FUNCTION_ARG_ACCESS_API select HAVE_FUNCTION_DESCRIPTORS if PPC64_ELF_ABI_V1
arch/riscv/Kconfig +1 -0
@@ -142,6 +142,7 @@ config RISCV select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE) select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS select HAVE_DYNAMIC_FTRACE_WITH_ARGS if HAVE_DYNAMIC_FTRACE + select HAVE_FTRACE_GRAPH_FUNC select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_GRAPH_FREGS
arch/x86/Kconfig +1 -0
@@ -232,6 +232,7 @@ config X86 select HAVE_EXIT_THREAD select HAVE_GUP_FAST select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE + select HAVE_FTRACE_GRAPH_FUNC if HAVE_FUNCTION_GRAPH_TRACER select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FUNCTION_GRAPH_FREGS if HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
kernel/trace/Kconfig +5 -0
@@ -34,6 +34,11 @@ config HAVE_FUNCTION_GRAPH_TRACER config HAVE_FUNCTION_GRAPH_FREGS bool +config HAVE_FTRACE_GRAPH_FUNC + bool + help + True if ftrace_graph_func() is defined. + config HAVE_DYNAMIC_FTRACE bool help
Masami Hiramatsu (Google)
maintainerPATCH v17 11/16 fprobe: Rewrite fprobe on function-graph tracer
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Rewrite fprobe implementation on function-graph tracer. Major API changes are:
- 'nr_maxactive' field is deprecated.
- This depends on CONFIG_DYNAMIC_FTRACE_WITH_ARGS or !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS, and CONFIG_HAVE_FUNCTION_GRAPH_FREGS. So currently works only on x86_64.
- Currently the entry size is limited in 15 * sizeof(long).
- If there is too many fprobe exit handler set on the same function, it will fail to probe.
---
Changes in v14:
- Add ftrace_regs_get_return_addresss() for riscv.
Changes in v12:
- Skip updating ftrace hash if not required.
Changes in v9:
- Remove unneeded prototype of ftrace_regs_get_return_address().
- Fix entry data address calculation.
- Remove DIV_ROUND_UP() from hotpath.
Changes in v8:
- Use trace_func_graph_ret/ent_t for fgraph_ops.
- Update CONFIG_FPROBE dependencies.
- Add ftrace_regs_get_return_address() for each arch.
Changes in v3:
- Update for new reserve_data/retrieve_data API.
- Fix internal push/pop on fgraph data logic so that it can correctly save/restore the returning fprobes.
Changes in v2:
- Add more lockdep_assert_held(fprobe_mutex)
- Use READ_ONCE() and WRITE_ONCE() for fprobe_hlist_node::fp.
- Add NOKPROBE_SYMBOL() for the functions which is called from entry/exit callback.
--- arch/arm64/include/asm/ftrace.h | 6 arch/loongarch/include/asm/ftrace.h | 6 arch/powerpc/include/asm/ftrace.h | 6 arch/riscv/include/asm/ftrace.h | 5 arch/s390/include/asm/ftrace.h | 6 arch/x86/include/asm/ftrace.h | 6 include/linux/fprobe.h | 53 ++- kernel/trace/Kconfig | 8 kernel/trace/fprobe.c | 639 +++++++++++++++++++++++++---------- lib/test_fprobe.c | 45 -- 10 files changed, 535 insertions(+), 245 deletions(-)
arch/arm64/include/asm/ftrace.h +6 -0
@@ -135,6 +135,12 @@ ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs)return arch_ftrace_regs (fregs)->fp; } +static __always_inline unsigned long +ftrace_regs_get_return_address (const struct ftrace_regs *fregs) +{ +return arch_ftrace_regs (fregs)->lr; +} + static __always_inline struct pt_regs *ftrace_partial_regs (const struct ftrace_regs *fregs,struct pt_regs *regs) {
arch/loongarch/include/asm/ftrace.h +6 -0
@@ -61,6 +61,12 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, unsigned long ip)#define ftrace_regs_get_frame_pointer (fregs) \ (arch_ftrace_regs(fregs)->regs.regs[22]) +static __always_inline unsigned long +ftrace_regs_get_return_address (struct ftrace_regs *fregs) +{ +return *(unsigned long *)(arch_ftrace_regs (fregs)->regs.regs[1 ]); +} +#define ftrace_graph_func ftrace_graph_funcvoid ftrace_graph_func (unsigned long ip,unsigned long parent_ip,struct ftrace_ops *op,struct ftrace_regs *fregs);
arch/powerpc/include/asm/ftrace.h +6 -0
@@ -54,6 +54,12 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,regs_set_return_ip (&arch_ftrace_regs (fregs)->regs, ip); } +static __always_inline unsigned long +ftrace_regs_get_return_address (struct ftrace_regs *fregs) +{ +return arch_ftrace_regs (fregs)->regs.link; +} +struct ftrace_ops ;#define ftrace_graph_func ftrace_graph_func
arch/riscv/include/asm/ftrace.h +5 -0
@@ -186,6 +186,11 @@ static __always_inline unsigned long ftrace_regs_get_return_value(const struct freturn arch_ftrace_regs (fregs)->a0; } +static __always_inline unsigned long ftrace_regs_get_return_address (const struct ftrace_regs *fregs) +{ +return arch_ftrace_regs (fregs)->ra; +} + static __always_inline void ftrace_regs_set_return_value(struct ftrace_regs *fregs,unsigned long ret) {
arch/s390/include/asm/ftrace.h +6 -0
@@ -76,6 +76,12 @@ ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs)return ftrace_regs_get_stack_pointer (fregs); } +static __always_inline unsigned long +ftrace_regs_get_return_address (const struct ftrace_regs *fregs) +{ +return arch_ftrace_regs (fregs)->regs.gprs[14 ]; +} +#define arch_ftrace_fill_perf_regs (fregs, _regs) do { \ (_regs)->psw.mask = 0; \ (_regs)->psw.addr = arch_ftrace_regs(fregs)->regs.psw.addr; \
arch/x86/include/asm/ftrace.h +6 -0
@@ -56,6 +56,12 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs) do { arch_ftrace_regs(fregs)->regs.ip = (_ip); } while (0) +static __always_inline unsigned long +ftrace_regs_get_return_address (struct ftrace_regs *fregs) +{ +return *(unsigned long *)ftrace_regs_get_stack_pointer (fregs); +} +struct ftrace_ops ;#define ftrace_graph_func ftrace_graph_func void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
include/linux/fprobe.h +38 -15
83 lines not on this page · raw message
kernel/trace/Kconfig +3 -5
@@ -307,11 +307,9 @@ config DYNAMIC_FTRACE_WITH_ARGS config FPROBE bool "Kernel Function Probe (fprobe)" - depends on FUNCTION_TRACER - depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS - depends on HAVE_FTRACE_REGS_HAVING_PT_REGS || !HAVE_DYNAMIC_FTRACE_WITH_ARGS - depends on HAVE_RETHOOK - select RETHOOK + depends on HAVE_FUNCTION_GRAPH_FREGS && HAVE_FTRACE_GRAPH_FUNC + select FUNCTION_GRAPH_TRACER + select DYNAMIC_FTRACE_WITH_ARGS default n help This option enables kernel function probe (fprobe) based on ftrace.
kernel/trace/fprobe.c +459 -180
769 lines not on this page · raw message
lib/test_fprobe.c +0 -45
85 lines not on this page · raw message
Sven Schnelle
reviewerRe: [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer
Quoted 42 lines · Masami Hiramatsu (Google)
From: Masami Hiramatsu (Google) <[email protected]>
Rewrite fprobe implementation on function-graph tracer. Major API changes are:
- 'nr_maxactive' field is deprecated.
- This depends onCONFIG_DYNAMIC_FTRACE_WITH_ARGSor !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS, andCONFIG_HAVE_FUNCTION_GRAPH_FREGS. So currently works only onx86_64.
- Currently the entry size is limited in 15 * sizeof(long).
- If there is too many fprobe exit handler set on the same function, it will fail to probe.Signed-off-by Masami Hiramatsu (Google) <[email protected]>Cc Steven Rostedt <[email protected]>Cc Mark Rutland <[email protected]>Cc Catalin Marinas <[email protected]>Cc Will Deacon <[email protected]>Cc Huacai Chen <[email protected]>Cc WANG Xuerui <[email protected]>Cc Michael Ellerman <[email protected]>Cc Nicholas Piggin <[email protected]>Cc Christophe Leroy <[email protected]>Cc Naveen N Rao <[email protected]>Cc Madhavan Srinivasan <[email protected]>Cc Paul Walmsley <[email protected]>Cc Palmer Dabbelt <[email protected]>Cc Albert Ou <[email protected]>Cc Heiko Carstens <[email protected]>Cc Vasily Gorbik <[email protected]>Cc Alexander Gordeev <[email protected]>Cc Christian Borntraeger <[email protected]>Cc Sven Schnelle <[email protected]>Cc Thomas Gleixner <[email protected]>Cc Ingo Molnar <[email protected]>Cc Borislav Petkov <[email protected]>Cc Dave Hansen <[email protected]>Cc "H. Peter Anvin" <[email protected]>Cc Mathieu Desnoyers <[email protected]>Cc Andrew Morton <[email protected]>
[..]
Quoted 5 lines
include/linux/fprobe.h +0
-0@@ -5,10 +5,11 @@
[..]
Quoted 11 lines
include/linux/fprobe.h +10
-0+static inline unsigned long encode_fprobe_header (struct fprobe *fp,int size_words) +{ +if (WARN_ON_ONCE (size_words >MAX_FPROBE_DATA_SIZE_WORD || + ((unsigned long )fp & ~FPROBE_HEADER_PTR_MASK ) != + ~FPROBE_HEADER_PTR_MASK )) { +return 0 ; } +return ((unsigned long )size_words <<FPROBE_HEADER_PTR_BITS ) | + ((unsigned long )fp &FPROBE_HEADER_PTR_MASK ); +} +
include/linux/fprobe.h
Quoted 10 lines
include/linux/fprobe.h +10
-0+/* Return reserved data size in words */ +static inline int decode_fprobe_header (unsigned long val,struct fprobe **fp) +{ +unsigned long ptr; + + ptr = (val &FPROBE_HEADER_PTR_MASK ) | ~FPROBE_HEADER_PTR_MASK ; +if (fp) + *fp = (struct fprobe *)ptr; +return val >>FPROBE_HEADER_PTR_BITS ; +}
I think that still has the issue that the size is encoded in the leftmost fields of the pointer, which doesn't work on all architectures. I reported this already in v15
(https://lore.kernel.org/all/[email protected]/)
Steven Rostedt
maintainerRe: [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer
Quoted 7 lines · On Wed, 16 Oct 2024 14:07:31 +0200 Sven Schnelle <[email protected]> wrote:
Quoted 7 lines
kernel/trace/fprobe.c +7
-0+/* Return reserved data size in words */ +static inline int decode_fprobe_header (unsigned long val,struct fprobe **fp) +{ +unsigned long ptr; + + ptr = (val &FPROBE_HEADER_PTR_MASK ) | ~FPROBE_HEADER_PTR_MASK ; +if (fp)
Quoted 8 lines
kernel/trace/fprobe.c line 174
Quoted 3 lines
kernel/trace/fprobe.c +3
-0+ *fp = (struct fprobe *)ptr; +return val >>FPROBE_HEADER_PTR_BITS ; +}I think that still has the issue that the size is encoded in the leftmost fields of the pointer, which doesn't work on all architectures. I reported this already in v15
(https://lore.kernel.org/all/[email protected]/)
From what you said in v15:
Quoted 5 lines
I haven't yet fully understood why this logic is needed, but the
WARN_ON_ONCEtriggers on s390. I'm assuming this fails because fp always has the upper bits of the address set on x86 (and likely others). As an example, in my test setup, fp is0x8feec218on s390, while it is0xffff888100add118in x86-kvm.
Since we only need to save 4 bits for size, we could have what it is replacing always be zero or always be f, depending on the arch. The question then is, is s390's 4 MSBs always zero?
Thus we could make it be:
static inline int decode_fprobe_header(unsigned long val, struct fprobe **fp)
{
unsigned long ptr;
ptr = (val & FPROBE_HEADER_PTR_MASK) | FPROBE_HEADER_MSB_MASK;
if (fp)
*fp = (struct fprobe *)ptr;
return val >> FPROBE_HEADER_PTR_BITS;
}And define FPROBE_HEADER_MSB_MASK to be either:
For most archs:
#define FPROBE_HEADER_MSB_MASK (0xf << FPROBE_HEADER_PTR_BITS)
or on s390:
#define FPROBE_HEADER_MSB_MASK (0x0)
Would this work?
-- Steve
Sven Schnelle
reviewerRe: [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer
Quoted 27 lines · Steven Rostedt
Quoted 7 lines · On Wed, 16 Oct 2024 14:07:31 +0200 Sven Schnelle <[email protected]> wrote:
Quoted 7 lines
kernel/trace/fprobe.c +7
-0+/* Return reserved data size in words */ +static inline int decode_fprobe_header (unsigned long val,struct fprobe **fp) +{ +unsigned long ptr; + + ptr = (val &FPROBE_HEADER_PTR_MASK ) | ~FPROBE_HEADER_PTR_MASK ; +if (fp)Quoted 8 lines
kernel/trace/fprobe.c line 174
Quoted 3 lines
kernel/trace/fprobe.c +3
-0+ *fp = (struct fprobe *)ptr; +return val >>FPROBE_HEADER_PTR_BITS ; +}I think that still has the issue that the size is encoded in the leftmost fields of the pointer, which doesn't work on all architectures. I reported this already in v15
(https://lore.kernel.org/all/[email protected]/)From what you said in v15:
Quoted 5 lines
I haven't yet fully understood why this logic is needed, but the
WARN_ON_ONCEtriggers on s390. I'm assuming this fails because fp always has the upper bits of the address set on x86 (and likely others). As an example, in my test setup, fp is0x8feec218on s390, while it is0xffff888100add118in x86-kvm.
Quoted 3 lines
Since we only need to save 4 bits for size, we could have what it is replacing always be zero or always be f, depending on the arch. The question then is, is s390's 4 MSBs always zero?
s390 has separate address spaces for kernel and userspace - so kernel addresses could be anywhere. I don't know think the range should be limited artifically because of some optimizations.
Steven Rostedt
maintainerRe: [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer
Quoted 8 lines · On Wed, 16 Oct 2024 20:13:25 +0200 Sven Schnelle <[email protected]> wrote:
Quoted 8 lines
From what you said in v15:
Quoted 5 lines
I haven't yet fully understood why this logic is needed, but the
WARN_ON_ONCEtriggers on s390. I'm assuming this fails because fp always has the upper bits of the address set on x86 (and likely others). As an example, in my test setup, fp is0x8feec218on s390, while it is0xffff888100add118in x86-kvm.
Quoted 7 lines
Quoted 3 lines
Since we only need to save 4 bits for size, we could have what it is replacing always be zero or always be f, depending on the arch. The question then is, is s390's 4 MSBs always zero?
s390 has separate address spaces for kernel and userspace - so kernel addresses could be anywhere. I don't know think the range should be limited artifically because of some optimizations.
Note, this is information saved in the shadow stack. When the first callback is attached to the fgraph tracer, all tasks will get a shadow stack. It currently defaults to PAGE_SIZE. When a function is entered and one of the callbacks wants to trace that function, information is saved on the shadow stack, including the original return address as the old return address is replaced to a call to a trampoline to jump to the return side callback on function exit.
We allow up to 16 callbacks to be attached to the tracer. Each that wants to trace the return side will have some information saved on this shadow stack. Note all information in the shadow stack is saved by natural word size (8 bytes on 64 bit machines, leaving 512 storage slots on 4096 size shadow stack).
Each entry callback can also reserve information on this shadow stack (in word aligned segments) that can be retrieved by the function exit callback.
This information we are storing is saved on this shadow stack. The optimization being done here is to not waste a full 8 bytes (1 slot on the shadow stack) for just 4 bits.
If we need to save the full fp, then there's no choice but to use a full slot to also save the 4 bits. If other architectures can do tricks to combine the size and fp, they should, to save the slots.
I also plan on changing the size of the shadow stack. We could even do that per architecture. Thus, if we need to use two slots on the shadow stack to save the fp and size, then we could make the shadow stack bigger for those architectures that need that.
-- Steve
Heiko Carstens
maintainerRe: [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer
In reply to Steven RostedtQuoted 28 lines · Steven Rostedt
Quoted 5 lines · On Wed, 16 Oct 2024 14:07:31 +0200 Sven Schnelle <[email protected]> wrote:
I haven't yet fully understood why this logic is needed, but the
WARN_ON_ONCEtriggers on s390. I'm assuming this fails because fp always has the upper bits of the address set on x86 (and likely others). As an example, in my test setup, fp is0x8feec218on s390, while it is0xffff888100add118in x86-kvm.Since we only need to save 4 bits for size, we could have what it is replacing always be zero or always be f, depending on the arch. The question then is, is s390's 4 MSBs always zero?
Thus we could make it be:
static inline int
decode_fprobe_header(unsigned long val, struct fprobe **fp){ unsigned long ptr; ptr = (val & FPROBE_HEADER_PTR_MASK) | FPROBE_HEADER_MSB_MASK; if (fp) *fp = (struct fprobe *)ptr; return val >> FPROBE_HEADER_PTR_BITS; }And define
FPROBE_HEADER_MSB_MASKto be either:For most archs:
Quoted 7 lines
#define
FPROBE_HEADER_MSB_MASK(0xf<<FPROBE_HEADER_PTR_BITS)or on s390:
#define
FPROBE_HEADER_MSB_MASK(0x0)Would this work?
This would work for s390. Right now we don't make any use of the four MSBs, and they are always zero. If for some reason this would ever change, we would need to come up with a different solution.
Please note that this only works for addresses in the kernel address space. For user space the full 64 bit address range (minus the top page) can be used for user space applications. I'm just writing this here, just in case something like this comes up for uprobes or something similar as well.
Masami Hiramatsu (Google)
maintainerRe: [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer
Quoted 33 lines · On Fri, 18 Oct 2024 14:49:52 +0200 Heiko Carstens <[email protected]> wrote:
Quoted 32 lines · Steven Rostedt
Quoted 5 lines · On Wed, 16 Oct 2024 14:07:31 +0200 Sven Schnelle <[email protected]> wrote:
I haven't yet fully understood why this logic is needed, but the
WARN_ON_ONCEtriggers on s390. I'm assuming this fails because fp always has the upper bits of the address set on x86 (and likely others). As an example, in my test setup, fp is0x8feec218on s390, while it is0xffff888100add118in x86-kvm.Since we only need to save 4 bits for size, we could have what it is replacing always be zero or always be f, depending on the arch. The question then is, is s390's 4 MSBs always zero?
Thus we could make it be:
static inline int
decode_fprobe_header(unsigned long val, struct fprobe **fp){ unsigned long ptr; ptr = (val & FPROBE_HEADER_PTR_MASK) | FPROBE_HEADER_MSB_MASK; if (fp) *fp = (struct fprobe *)ptr; return val >> FPROBE_HEADER_PTR_BITS; }And define
FPROBE_HEADER_MSB_MASKto be either:For most archs:
#define
FPROBE_HEADER_MSB_MASK(0xf<<FPROBE_HEADER_PTR_BITS)or on s390:
Quoted 7 lines
Quoted 3 lines
#define
FPROBE_HEADER_MSB_MASK(0x0)Would this work?
This would work for s390. Right now we don't make any use of the four MSBs, and they are always zero. If for some reason this would ever change, we would need to come up with a different solution.
Ah, so fill with zero works for s390 kernel. Thanks for the info.
Quoted 3 lines
Please note that this only works for addresses in the kernel address space. For user space the full 64 bit address range (minus the top page) can be used for user space applications.
I wonder what is the unsigned long size (stack entry size) of the s390? is it 64bit?
Quoted 3 lines
I'm just writing this
here, just in case something like this comes up for uprobes or something similar as well.
I'm considering another solution if it doesn't work. Of course if above works, it is the best compression ratio.
This is only if it doesn't work, we can consolidate a set of fprobe header in N + 1 entries as
0: [# of fprobes(4bit)|4bit array of sizes]
1: [fp 1]
2: [fp 1 data]
...
So if we have 3 fprobes on the same entry and has 0, 3, 2 data size, then
0:[3|0|3|2|0...0]
1:[fp1]
2:[fp2]
3:[fp2 data 1]
4:[fp2 data 2]
5:[fp2 data 3]
6:[fp3]
7:[fp3 data 1]
8:[fp3 data 2]
Thank you,
Signature · 1 line
Masami Hiramatsu (Google) <[email protected]>
Heiko Carstens
maintainerRe: [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer
Quoted 6 lines
Quoted 3 lines
Please note that this only works for addresses in the kernel address space. For user space the full 64 bit address range (minus the top page) can be used for user space applications.
I wonder what is the unsigned long size (stack entry size) of the s390? is it 64bit?
The s390 kernel is 64 bit only. So unsigned long is 64 bit as well.
Quoted 6 lines
Quoted 3 lines
I'm just writing this
here, just in case something like this comes up for uprobes or something similar as well.I'm considering another solution if it doesn't work. Of course if above works, it is the best compression ratio.
I'm think we are not talking about uprobes here, and everything ftrace related would just work (tm) with the first four MSBs assumed to be zero.
Masami Hiramatsu (Google)
maintainerRe: [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer
Quoted 9 lines · On Mon, 21 Oct 2024 18:31:39 +0200 Heiko Carstens <[email protected]> wrote:
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Please note that this only works for addresses in the kernel address space. For user space the full 64 bit address range (minus the top page) can be used for user space applications.
I wonder what is the unsigned long size (stack entry size) of the s390? is it 64bit?
The s390 kernel is 64 bit only. So unsigned long is 64 bit as well.
Ah, got it.
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I'm just writing this
here, just in case something like this comes up for uprobes or something similar as well.I'm considering another solution if it doesn't work. Of course if above works, it is the best compression ratio.
I'm think we are not talking about uprobes here, and everything ftrace related would just work (tm) with the first four MSBs assumed to be zero.
yeah, but we still have other 32bit architectures support (e.g. i386, arm).
Thank you,
Signature · 1 line
Masami Hiramatsu (Google) <[email protected]>
Masami Hiramatsu (Google)
maintainerRe: [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer
In reply to Sven SchnelleQuoted 70 lines · On Wed, 16 Oct 2024 14:07:31 +0200 Sven Schnelle <[email protected]> wrote:
Quoted 42 lines · Masami Hiramatsu (Google)
From: Masami Hiramatsu (Google) <[email protected]>
Rewrite fprobe implementation on function-graph tracer. Major API changes are:
- 'nr_maxactive' field is deprecated.
- This depends onCONFIG_DYNAMIC_FTRACE_WITH_ARGSor !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS, andCONFIG_HAVE_FUNCTION_GRAPH_FREGS. So currently works only onx86_64.
- Currently the entry size is limited in 15 * sizeof(long).
- If there is too many fprobe exit handler set on the same function, it will fail to probe.Signed-off-by Masami Hiramatsu (Google) <[email protected]>Cc Steven Rostedt <[email protected]>Cc Mark Rutland <[email protected]>Cc Catalin Marinas <[email protected]>Cc Will Deacon <[email protected]>Cc Huacai Chen <[email protected]>Cc WANG Xuerui <[email protected]>Cc Michael Ellerman <[email protected]>Cc Nicholas Piggin <[email protected]>Cc Christophe Leroy <[email protected]>Cc Naveen N Rao <[email protected]>Cc Madhavan Srinivasan <[email protected]>Cc Paul Walmsley <[email protected]>Cc Palmer Dabbelt <[email protected]>Cc Albert Ou <[email protected]>Cc Heiko Carstens <[email protected]>Cc Vasily Gorbik <[email protected]>Cc Alexander Gordeev <[email protected]>Cc Christian Borntraeger <[email protected]>Cc Sven Schnelle <[email protected]>Cc Thomas Gleixner <[email protected]>Cc Ingo Molnar <[email protected]>Cc Borislav Petkov <[email protected]>Cc Dave Hansen <[email protected]>Cc "H. Peter Anvin" <[email protected]>Cc Mathieu Desnoyers <[email protected]>Cc Andrew Morton <[email protected]>[..]
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include/linux/fprobe.h +0
-0@@ -5,10 +5,11 @@[..]
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include/linux/fprobe.h +17
-0+static inline unsigned long encode_fprobe_header (struct fprobe *fp,int size_words) +{ +if (WARN_ON_ONCE (size_words >MAX_FPROBE_DATA_SIZE_WORD || + ((unsigned long )fp & ~FPROBE_HEADER_PTR_MASK ) != + ~FPROBE_HEADER_PTR_MASK )) { +return 0 ; } +return ((unsigned long )size_words <<FPROBE_HEADER_PTR_BITS ) | + ((unsigned long )fp &FPROBE_HEADER_PTR_MASK ); +} + +/* Return reserved data size in words */ +static inline int decode_fprobe_header (unsigned long val,struct fprobe **fp) +{ +unsigned long ptr; + + ptr = (val &FPROBE_HEADER_PTR_MASK ) | ~FPROBE_HEADER_PTR_MASK ; +if (fp)
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include/linux/fprobe.h
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include/linux/fprobe.h +3
-0+ *fp = (struct fprobe *)ptr; +return val >>FPROBE_HEADER_PTR_BITS ; +}I think that still has the issue that the size is encoded in the leftmost fields of the pointer, which doesn't work on all architectures. I reported this already in v15
(https://lore.kernel.org/all/[email protected]/)
Oops, thanks for reporting. I should missed that.
Quoted 5 lines
I haven't yet fully understood why this logic is needed, but the
WARN_ON_ONCEtriggers on s390. I'm assuming this fails because fp always has the upper bits of the address set on x86 (and likely others). As an example, in my test setup, fp is0x8feec218on s390, while it is0xffff888100add118in x86-kvm.
Ah, so s390 kernel/user memory layout is something like 4G/4G? Hmm, this encode expects the leftmost 4bit is filled. For the architecture which has 32bit address space, we may be possible to use "unsigned long long" for 'val' on shadow stack (and use the first 32bit for fp and another 32bit for size).
Anyway, I need to redesign it depending on architecture.
Thank you!
Signature · 1 line
Masami Hiramatsu (Google) <[email protected]>
Sven Schnelle
reviewerRe: [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer
Quoted 16 lines · Masami Hiramatsu (Google)
Quoted 5 lines · On Wed, 16 Oct 2024 14:07:31 +0200 Sven Schnelle <[email protected]> wrote:
"Masami Hiramatsu (Google)" <[email protected]> writes:
I think that still has the issue that the size is encoded in the leftmost fields of the pointer, which doesn't work on all architectures. I reported this already in v15
(https://lore.kernel.org/all/[email protected]/)Oops, thanks for reporting. I should missed that.
Quoted 5 lines
I haven't yet fully understood why this logic is needed, but the
WARN_ON_ONCEtriggers on s390. I'm assuming this fails because fp always has the upper bits of the address set on x86 (and likely others). As an example, in my test setup, fp is0x8feec218on s390, while it is0xffff888100add118in x86-kvm.
Quoted 7 lines
Ah, so s390 kernel/user memory layout is something like 4G/4G? Hmm, this encode expects the leftmost 4bit is filled. For the architecture which has 32bit address space, we may be possible to use "unsigned long long" for 'val' on shadow stack (and use the first 32bit for fp and another 32bit for size).
Anyway, I need to redesign it depending on architecture.
Could you explain a bit more what redesign means? Thanks!
Masami Hiramatsu (Google)
maintainerRe: [PATCH v17 11/16] fprobe: Rewrite fprobe on function-graph tracer
Quoted 24 lines · On Wed, 16 Oct 2024 20:14:54 +0200 Sven Schnelle <[email protected]> wrote:
Quoted 22 lines · Masami Hiramatsu (Google)
Quoted 5 lines · On Wed, 16 Oct 2024 14:07:31 +0200 Sven Schnelle <[email protected]> wrote:
"Masami Hiramatsu (Google)" <[email protected]> writes:
I think that still has the issue that the size is encoded in the leftmost fields of the pointer, which doesn't work on all architectures. I reported this already in v15
(https://lore.kernel.org/all/[email protected]/)Oops, thanks for reporting. I should missed that.
Quoted 5 lines
I haven't yet fully understood why this logic is needed, but the
WARN_ON_ONCEtriggers on s390. I'm assuming this fails because fp always has the upper bits of the address set on x86 (and likely others). As an example, in my test setup, fp is0x8feec218on s390, while it is0xffff888100add118in x86-kvm.Ah, so s390 kernel/user memory layout is something like 4G/4G? Hmm, this encode expects the leftmost 4bit is filled. For the architecture which has 32bit address space, we may be possible to use "unsigned long long" for 'val' on shadow stack (and use the first 32bit for fp and another 32bit for size).
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Anyway, I need to redesign it depending on architecture.
Could you explain a bit more what redesign means? Thanks!
This "encoded" data is for recording the *fp (the address of fprobe) and its data size into one value and storing it on the shadow stack.
On x86-64, the kernel objects are puts on the highest memory address, thus the highest bits are always same. So it uses 4bits for recording the data size. Most of other 64bit architecture are similar memory layout, so we can use the highest bits. Note that the data size must be a multiplier of u64 (== 8byte), so 4bits is enough since shadow stack size is limited.
The s390 and other 32bit address space architectures need special care for it. Thus I think we can use 2 slots (= 2 * u32) for saving data in this case.
Thank you,
Signature · 1 line
Masami Hiramatsu (Google) <[email protected]>
Masami Hiramatsu (Google)
maintainerPATCH v17 12/16 tracing/fprobe: Remove nr_maxactive from fprobe
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Remove depercated fprobe::nr_maxactive. This involves fprobe events to rejects the maxactive number.
---
Changes in v2:
- Newly added.
--- include/linux/fprobe.h | 2 -- kernel/trace/trace_fprobe.c | 43 ++++++------------------------------------- 2 files changed, 6 insertions(+), 39 deletions(-)
include/linux/fprobe.h +0 -2
@@ -54,7 +54,6 @@ struct fprobe_hlist {* @nmissed: The counter for missing events. * @flags: The status flag. * @entry_data_size: The private data storage size. -* @nr_maxactive: The max number of active functions. (*deprecated) * @entry_handler: The callback function for function entry. * @exit_handler: The callback function for function exit. * @hlist_array: The fprobe_hlist for fprobe search from IP hash table.
@@ -63,7 +62,6 @@ struct fprobe {unsigned long nmissed;unsigned int flags;size_t entry_data_size; -int nr_maxactive;fprobe_entry_cb entry_handler;fprobe_exit_cb exit_handler;
kernel/trace/trace_fprobe.c +6 -37
92 lines not on this page · raw message
Masami Hiramatsu (Google)
maintainerPATCH v17 13/16 selftests: ftrace: Remove obsolate maxactive syntax check
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Since the fprobe event does not support maxactive anymore, stop testing the maxactive syntax error checking.
--- .../ftrace/test.d/dynevent/fprobe_syntax_errors.tc | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc +1 -3
@@ -16,9 +16,7 @@ aarch64) REG=%r0 ;; esac -check_error 'f^100 vfs_read' # MAXACT_NO_KPROBE -check_error 'f^1a111 vfs_read' # BAD_MAXACT -check_error 'f^100000 vfs_read' # MAXACT_TOO_BIG +check_error 'f^100 vfs_read' # BAD_MAXACT check_error 'f ^non_exist_func' # BAD_PROBE_ADDR (enoent) check_error 'f ^vfs_read+10' # BAD_PROBE_ADDR
Masami Hiramatsu (Google)
maintainerPATCH v17 14/16 selftests/ftrace: Add a test case for repeating register/unregister fprobe
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
This test case repeats define and undefine the fprobe dynamic event to ensure that the fprobe does not cause any issue with such operations.
--- .../test.d/dynevent/add_remove_fprobe_repeat.tc | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_repeat.tc
tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_repeat.tc new file +19 -0
@@ -0,0 +1,19 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Generic dynamic event - Repeating add/remove fprobe events +# requires: dynamic_events "f[:[<group>/][<event>]] <func-name>[%return] [<args>]":README + +echo 0 > events/enable +echo > dynamic_events + +PLACE=$FUNCTION_FORK +REPEAT_TIMES=64 + +for i in `seq 1 $REPEAT_TIMES`; do + echo "f:myevent $PLACE" >> dynamic_events + grep -q myevent dynamic_events + test -d events/fprobes/myevent + echo > dynamic_events +done + +clear_trace
Masami Hiramatsu (Google)
maintainerPATCH v17 15/16 Documentation: probes: Update fprobe on function-graph tracer
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Update fprobe documentation for the new fprobe on function-graph tracer. This includes some bahvior changes and pt_regs to ftrace_regs interface change.
---
Changes in v2:
- Update @fregs parameter explanation.
--- Documentation/trace/fprobe.rst | 42 ++++++++++++++++++++++++++-------------- 1 file changed, 27 insertions(+), 15 deletions(-)
Documentation/trace/fprobe.rst +27 -15
@@ -9,9 +9,10 @@ Fprobe - Function entry/exit probe Introduction ============ -Fprobe is a function entry/exit probe mechanism based on ftrace. -Instead of using ftrace full feature, if you only want to attach callbacks -on function entry and exit, similar to the kprobes and kretprobes, you can +Fprobe is a function entry/exit probe mechanism based on the function-graph +tracer. +Instead of tracing all functions, if you want to attach callbacks on specific +function entry and exit, similar to the kprobes and kretprobes, you can use fprobe. Compared with kprobes and kretprobes, fprobe gives faster instrumentation for multiple functions with single handler. This document describes how to use fprobe.
@@ -91,12 +92,14 @@ The prototype of the entry/exit callback function are as follows: .. code-block:: c - int entry_callback(struct fprobe *fp, unsigned long entry_ip, unsigned long ret_ip, struct pt_regs *regs, void *entry_data); + int entry_callback(struct fprobe *fp, unsigned long entry_ip, unsigned long ret_ip, struct ftrace_regs *fregs, void *entry_data); - void exit_callback(struct fprobe *fp, unsigned long entry_ip, unsigned long ret_ip, struct pt_regs *regs, void *entry_data); + void exit_callback(struct fprobe *fp, unsigned long entry_ip, unsigned long ret_ip, struct ftrace_regs *fregs, void *entry_data); -Note that the @entry_ip is saved at function entry and passed to exit handler. -If the entry callback function returns !0, the corresponding exit callback will be cancelled. +Note that the @entry_ip is saved at function entry and passed to exit +handler. +If the entry callback function returns !0, the corresponding exit callback +will be cancelled. @fp This is the address of `fprobe` data structure related to this handler.
@@ -112,12 +115,10 @@ If the entry callback function returns !0, the corresponding exit callback will This is the return address that the traced function will return to, somewhere in the caller. This can be used at both entry and exit. -@regs - This is the `pt_regs` data structure at the entry and exit. Note that - the instruction pointer of @regs may be different from the @entry_ip - in the entry_handler. If you need traced instruction pointer, you need - to use @entry_ip. On the other hand, in the exit_handler, the instruction - pointer of @regs is set to the current return address. +@fregs + This is the `ftrace_regs` data structure at the entry and exit. This + includes the function parameters, or the return values. So user can + access thos values via appropriate `ftrace_regs_*` APIs. @entry_data This is a local storage to share the data between entry and exit handlers.
@@ -125,6 +126,17 @@ If the entry callback function returns !0, the corresponding exit callback will and `entry_data_size` field when registering the fprobe, the storage is allocated and passed to both `entry_handler` and `exit_handler`. +Entry data size and exit handlers on the same function +====================================================== + +Since the entry data is passed via per-task stack and it is has limited size, +the entry data size per probe is limited to `15 * sizeof(long)`. You also need +to take care that the different fprobes are probing on the same function, this +limit becomes smaller. The entry data size is aligned to `sizeof(long)` and +each fprobe which has exit handler uses a `sizeof(long)` space on the stack, +you should keep the number of fprobes on the same function as small as +possible. + Share the callbacks with kprobes ================================
@@ -165,8 +177,8 @@ This counter counts up when; - fprobe fails to take ftrace_recursion lock. This usually means that a function which is traced by other ftrace users is called from the entry_handler. - - fprobe fails to setup the function exit because of the shortage of rethook - (the shadow stack for hooking the function return.) + - fprobe fails to setup the function exit because of failing to allocate the + data buffer from the per-task shadow stack. The `fprobe::nmissed` field counts up in both cases. Therefore, the former skips both of entry and exit callback and the latter skips the exit
Masami Hiramatsu (Google)
maintainerPATCH v17 16/16 bpf: Add get_entry_ip() for arm64
In reply to Masami Hiramatsu (Google)From: Masami Hiramatsu (Google) <[email protected]>
Add get_entry_ip() implementation for arm64. This is based on the information in ftrace_call_adjust() on arm64. Basically function entry address = ftrace call entry_ip - 4, but when there is a BTI at the first instruction, we need one more instruction back (entry_ip - 8.)
--- kernel/trace/bpf_trace.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+)
kernel/trace/bpf_trace.c +64 -0
@@ -1042,6 +1042,70 @@ static unsigned long get_entry_ip(unsigned long fentry_ip) fentry_ip -=ENDBR_INSN_SIZE ;return fentry_ip; } +#elif defined(CONFIG_ARM64 ) +#include <asm/insn.h> + +static unsigned long get_entry_ip (unsigned long fentry_ip) +{ +u32 insn; + +/* +* When using patchable-function-entry without pre-function NOPS, ftrace +* entry is the address of the first NOP after the function entry point. +* +* The compiler has either generated: +* +* func+00: func: NOP // To be patched to MOV X9, LR +* func+04: NOP // To be patched to BL <caller> +* +* Or: +* +* func-04: BTI C +* func+00: func: NOP // To be patched to MOV X9, LR +* func+04: NOP // To be patched to BL <caller> +* +* The fentry_ip is the address of `BL <caller>` which is at `func + 4` +* bytes in either case. +*/ +if (!IS_ENABLED (CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS )) +return fentry_ip -AARCH64_INSN_SIZE ; + +/* +* When using patchable-function-entry with pre-function NOPs, BTI is +* a bit different. +* +* func+00: func: NOP // To be patched to MOV X9, LR +* func+04: NOP // To be patched to BL <caller> +* +* Or: +* +* func+00: func: BTI C +* func+04: NOP // To be patched to MOV X9, LR +* func+08: NOP // To be patched to BL <caller> +* +* The fentry_ip is the address of `BL <caller>` which is at either +* `func + 4` or `func + 8` depends on whether there is a BTI. +*/ + +/* If there is no BTI, the func address should be one instruction before. */ +if (!IS_ENABLED (CONFIG_ARM64_BTI_KERNEL )) +return fentry_ip -AARCH64_INSN_SIZE ; + +/* We want to be extra safe in case entry ip is on the page edge, +* but otherwise we need to avoid get_kernel_nofault()'s overhead. +*/ +if ((fentry_ip & ~PAGE_MASK ) <AARCH64_INSN_SIZE *2 ) { +if (get_kernel_nofault (insn, (u32 *)(fentry_ip -AARCH64_INSN_SIZE *2 ))) +return fentry_ip -AARCH64_INSN_SIZE ; + }else { + insn = *(u32 *)(fentry_ip -AARCH64_INSN_SIZE *2 ); + } + +if (aarch64_insn_is_bti (le32_to_cpu ((__le32 )insn))) +return fentry_ip -AARCH64_INSN_SIZE *2 ; + +return fentry_ip -AARCH64_INSN_SIZE ; +}#else #define get_entry_ip (fentry_ip) fentry_ip#endif