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bpf: Add missed stats for kprobes

PATCH Superseded Jiri Olsa 5 participants 34 messages Aug 28, 2023 – Sep 5, 2023

Subsystems (9)
Kselftest BPF Tracing Arm STM32 +5 more subsystems

v1 of 3 Superseded Latest is v3 →

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Jiri Olsa

author reviewer
#0 lore raw

cover bpf: Add missed stats for kprobes

hi,
at the moment we can't retrieve the number of missed kprobe executions and subsequent execution of BPF programs.

This patchset adds:
- counting of missed execution on attach layer for:
. kprobes attached through perf link (kprobe/ftrace)
. kprobes attached through kprobe.multi link (fprobe)
- counting of recursion_misses for BPF kprobe programs
- counting runtime stats (kernel.bpf_stats_enabled=1) for BPF programs executed through bpf_prog_run_array - kprobes, perf events, trace syscall probes

It's still technically possible to create kprobe without perf link (using SET_BPF perf ioctl) in which case we don't have a way to retrieve the kprobe's 'missed' count. However both libbpf and cilium/ebpf libraries use perf link if it's available, and for old kernels without perf link support we can use BPF program to retrieve the kprobe missed count.

Also available at:
https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
bpf/missed_stats

thanks,
jirka

---
Jiri Olsa (12):
bpf: Move update_prog_stats to syscall object
bpf: Move bpf_prog_start_time to linux/filter.h
bpf: Count stats for kprobe_multi programs
bpf: Add missed value to kprobe_multi link info
bpf: Add missed value to kprobe perf link info
bpf: Count missed stats in trace_call_bpf
bpf: Move bpf_prog_run_array down in the header file
bpf: Count run stats in bpf_prog_run_array
bpftool: Display missed count for kprobe_multi link
bpftool: Display missed count for kprobe perf link selftests/bpf: Add test missed counts of perf event link kprobe elftests/bpf: Add test recursion stats of perf event link kprobe

 include/linux/bpf.h                                         | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------------------------
 include/linux/trace_events.h                                |   6 ++++--
 include/uapi/linux/bpf.h                                    |   2 ++
 kernel/bpf/syscall.c                                        |  36 +++++++++++++++++++++++++------
 kernel/bpf/trampoline.c                                     |  45 +++++----------------------------------
 kernel/trace/bpf_trace.c                                    |  17 ++++++++++++---
 kernel/trace/trace_kprobe.c                                 |   5 ++++-
 tools/bpf/bpftool/link.c                                    |   8 ++++++-
 tools/include/uapi/linux/bpf.h                              |   2 ++
 tools/testing/selftests/bpf/DENYLIST.aarch64                |   1 +
 tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c       |   5 +++++
 tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h |   2 ++
 tools/testing/selftests/bpf/prog_tests/missed.c             |  97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/missed_kprobe.c           |  30 ++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c |  48 +++++++++++++++++++++++++++++++++++++++++
 15 files changed, 327 insertions(+), 83 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/missed.c
 create mode 100644 tools/testing/selftests/bpf/progs/missed_kprobe.c
 create mode 100644 tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c
author reviewer
#1 lore raw

PATCH 1/12 bpf: Move update_prog_stats to syscall object

Moving update_prog_stats function to syscall object and making it global together with NO_START_TIME macro and adding 'bpf_' prefix for both.

It will be used by other program types in following changes.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/linux/bpf.h     |  7 +++++++
 kernel/bpf/syscall.c    | 22 ++++++++++++++++++++++
 kernel/bpf/trampoline.c | 37 +++++++------------------------------
 3 files changed, 36 insertions(+), 30 deletions(-)
include/linux/bpf.h +7 -0
index 12596af59c00..05eece17a989 100644
@@ -1982,6 +1982,8 @@ bpf_prog_run_array_uprobe(const struct bpf_prog_array __rcu *array_rcu,
 	return ret;
 }
 
+#define BPF_PROG_NO_START_TIME 1
+
 #ifdef CONFIG_BPF_SYSCALL
 DECLARE_PER_CPU(int, bpf_prog_active);
 extern struct mutex bpf_stats_enabled_mutex;

@@ -2456,6 +2458,7 @@ static inline bool has_current_bpf_ctx(void)
 }
 
 void notrace bpf_prog_inc_misses_counter(struct bpf_prog *prog);
+void notrace bpf_prog_update_prog_stats(struct bpf_prog *prog, u64 start);
 
 void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data,
 		     enum bpf_dynptr_type type, u32 offset, u32 size);

@@ -2695,6 +2698,10 @@ static inline void bpf_prog_inc_misses_counter(struct bpf_prog *prog)
 {
 }
 
+static void bpf_prog_update_prog_stats(struct bpf_prog *prog, u64 start)
+{
+}
+
 static inline void bpf_cgrp_storage_free(struct cgroup *cgroup)
 {
 }
kernel/bpf/syscall.c +22 -0
index ebeb0695305a..5d39d98f5eb1 100644
@@ -2188,6 +2188,28 @@ void notrace bpf_prog_inc_misses_counter(struct bpf_prog *prog)
 	u64_stats_update_end_irqrestore(&stats->syncp, flags);
 }
 
+void notrace bpf_prog_update_prog_stats(struct bpf_prog *prog,
+					u64 start)
+{
+	struct bpf_prog_stats *stats;
+
+	if (static_branch_unlikely(&bpf_stats_enabled_key) &&
+	    /* static_key could be enabled in __bpf_prog_enter*
+	     * and disabled in __bpf_prog_exit*.
+	     * And vice versa.
+	     * Hence check that 'start' is valid.
+	     */
+	    start > BPF_PROG_NO_START_TIME) {
+		unsigned long flags;
+
+		stats = this_cpu_ptr(prog->stats);
+		flags = u64_stats_update_begin_irqsave(&stats->syncp);
+		u64_stats_inc(&stats->cnt);
+		u64_stats_add(&stats->nsecs, sched_clock() - start);
+		u64_stats_update_end_irqrestore(&stats->syncp, flags);
+	}
+}
+
 static void bpf_prog_get_stats(const struct bpf_prog *prog,
 			       struct bpf_prog_kstats *stats)
 {
kernel/bpf/trampoline.c +7 -30
index 78acf28d4873..a6528e847fae 100644
@@ -819,15 +819,14 @@ void bpf_trampoline_put(struct bpf_trampoline *tr)
 	mutex_unlock(&trampoline_mutex);
 }
 
-#define NO_START_TIME 1
 static __always_inline u64 notrace bpf_prog_start_time(void)
 {
-	u64 start = NO_START_TIME;
+	u64 start = BPF_PROG_NO_START_TIME;
 
 	if (static_branch_unlikely(&bpf_stats_enabled_key)) {
 		start = sched_clock();
 		if (unlikely(!start))
-			start = NO_START_TIME;
+			start = BPF_PROG_NO_START_TIME;
 	}
 	return start;
 }

@@ -860,35 +859,13 @@ static u64 notrace __bpf_prog_enter_recur(struct bpf_prog *prog, struct bpf_tram
 	return bpf_prog_start_time();
 }
 
-static void notrace update_prog_stats(struct bpf_prog *prog,
-				      u64 start)
-{
-	struct bpf_prog_stats *stats;
-
-	if (static_branch_unlikely(&bpf_stats_enabled_key) &&
-	    /* static_key could be enabled in __bpf_prog_enter*
-	     * and disabled in __bpf_prog_exit*.
-	     * And vice versa.
-	     * Hence check that 'start' is valid.
-	     */
-	    start > NO_START_TIME) {
-		unsigned long flags;
-
-		stats = this_cpu_ptr(prog->stats);
-		flags = u64_stats_update_begin_irqsave(&stats->syncp);
-		u64_stats_inc(&stats->cnt);
-		u64_stats_add(&stats->nsecs, sched_clock() - start);
-		u64_stats_update_end_irqrestore(&stats->syncp, flags);
-	}
-}
-
 static void notrace __bpf_prog_exit_recur(struct bpf_prog *prog, u64 start,
 					  struct bpf_tramp_run_ctx *run_ctx)
 	__releases(RCU)
 {
 	bpf_reset_run_ctx(run_ctx->saved_run_ctx);
 
-	update_prog_stats(prog, start);
+	bpf_prog_update_prog_stats(prog, start);
 	this_cpu_dec(*(prog->active));
 	migrate_enable();
 	rcu_read_unlock();

@@ -906,7 +883,7 @@ static u64 notrace __bpf_prog_enter_lsm_cgroup(struct bpf_prog *prog,
 
 	run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx);
 
-	return NO_START_TIME;
+	return BPF_PROG_NO_START_TIME;
 }
 
 static void notrace __bpf_prog_exit_lsm_cgroup(struct bpf_prog *prog, u64 start,

@@ -941,7 +918,7 @@ void notrace __bpf_prog_exit_sleepable_recur(struct bpf_prog *prog, u64 start,
 {
 	bpf_reset_run_ctx(run_ctx->saved_run_ctx);
 
-	update_prog_stats(prog, start);
+	bpf_prog_update_prog_stats(prog, start);
 	this_cpu_dec(*(prog->active));
 	migrate_enable();
 	rcu_read_unlock_trace();

@@ -964,7 +941,7 @@ static void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start,
 {
 	bpf_reset_run_ctx(run_ctx->saved_run_ctx);
 
-	update_prog_stats(prog, start);
+	bpf_prog_update_prog_stats(prog, start);
 	migrate_enable();
 	rcu_read_unlock_trace();
 }

@@ -987,7 +964,7 @@ static void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start,
 {
 	bpf_reset_run_ctx(run_ctx->saved_run_ctx);
 
-	update_prog_stats(prog, start);
+	bpf_prog_update_prog_stats(prog, start);
 	migrate_enable();
 	rcu_read_unlock();
 }
Signature · 1 line
2.41.0
#2 lore raw

Re: [PATCH bpf-next 01/12] bpf: Move update_prog_stats to syscall object

Review

Quoted 9 lines · Jiri Olsa

static void notrace __bpf_prog_exit_recur(struct bpf_prog *prog, u64 start,
struct bpf_tramp_run_ctx *run_ctx)
__releases(RCU)

 {
        bpf_reset_run_ctx(run_ctx->saved_run_ctx);
(quoted diff) +1 -1
-       update_prog_stats(prog, start);
+       bpf_prog_update_prog_stats(prog, start);

I bet this adds a noticeable performance regression. The function was inlined before and the static key made it a nop. Above makes it into a function call.
Please use always_inline and move it to a header.

#3 lore raw

Re: [PATCH bpf-next 01/12] bpf: Move update_prog_stats to syscall object

Quoted 8 lines · Alexei Starovoitov
Quoted 7 lines · Jiri Olsa

static void notrace __bpf_prog_exit_recur(struct bpf_prog *prog, u64 start,
struct bpf_tramp_run_ctx *run_ctx)
__releases(RCU)

 {
        bpf_reset_run_ctx(run_ctx->saved_run_ctx);
Quoted 7 lines

Review

Quoted 2 lines
(quoted diff) +1 -1
-       update_prog_stats(prog, start);
+       bpf_prog_update_prog_stats(prog, start);

I bet this adds a noticeable performance regression. The function was inlined before and the static key made it a nop. Above makes it into a function call.
Please use always_inline and move it to a header.

right.. will change

thanks,
jirka

author reviewer
#4 lore raw

PATCH 2/12 bpf: Move bpf_prog_start_time to linux/filter.h

In reply to Jiri Olsa

Moving bpf_prog_start_time to linux/filter.h and making it globally available.

It will be used by other program types in following changes.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/linux/bpf.h     | 20 ++++++++++++++++++++
 kernel/bpf/trampoline.c | 12 ------------
 2 files changed, 20 insertions(+), 12 deletions(-)
include/linux/bpf.h +20 -0
index 05eece17a989..23a73f52c7bc 100644
@@ -29,6 +29,9 @@
 #include <linux/rcupdate_trace.h>
 #include <linux/static_call.h>
 #include <linux/memcontrol.h>
+#include <linux/sched/clock.h>
+
+DECLARE_STATIC_KEY_FALSE(bpf_stats_enabled_key);
 
 struct bpf_verifier_env;
 struct bpf_verifier_log;

@@ -2460,6 +2463,18 @@ static inline bool has_current_bpf_ctx(void)
 void notrace bpf_prog_inc_misses_counter(struct bpf_prog *prog);
 void notrace bpf_prog_update_prog_stats(struct bpf_prog *prog, u64 start);
 
+static __always_inline u64 notrace bpf_prog_start_time(void)
+{
+	u64 start = BPF_PROG_NO_START_TIME;
+
+	if (static_branch_unlikely(&bpf_stats_enabled_key)) {
+		start = sched_clock();
+		if (unlikely(!start))
+			start = BPF_PROG_NO_START_TIME;
+	}
+	return start;
+}
+
 void bpf_dynptr_init(struct bpf_dynptr_kern *ptr, void *data,
 		     enum bpf_dynptr_type type, u32 offset, u32 size);
 void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr);

@@ -2702,6 +2717,11 @@ static void bpf_prog_update_prog_stats(struct bpf_prog *prog, u64 start)
 {
 }
 
+static inline u64 notrace bpf_prog_start_time(void)
+{
+	return 0;
+}
+
 static inline void bpf_cgrp_storage_free(struct cgroup *cgroup)
 {
 }
kernel/bpf/trampoline.c +0 -12
index a6528e847fae..ed5b014f9532 100644
@@ -819,18 +819,6 @@ void bpf_trampoline_put(struct bpf_trampoline *tr)
 	mutex_unlock(&trampoline_mutex);
 }
 
-static __always_inline u64 notrace bpf_prog_start_time(void)
-{
-	u64 start = BPF_PROG_NO_START_TIME;
-
-	if (static_branch_unlikely(&bpf_stats_enabled_key)) {
-		start = sched_clock();
-		if (unlikely(!start))
-			start = BPF_PROG_NO_START_TIME;
-	}
-	return start;
-}
-
 /* The logic is similar to bpf_prog_run(), but with an explicit
  * rcu_read_lock() and migrate_disable() which are required
  * for the trampoline. The macro is split into
Signature · 1 line
2.41.0
Acked-by on v1 2/12
#5 lore raw

Re: [PATCH bpf-next 02/12] bpf: Move bpf_prog_start_time to linux/filter.h

Quoted 6 lines · Jiri Olsa

Moving bpf_prog_start_time to linux/filter.h and making it globally available.

It will be used by other program types in following changes.

Signed-off-by Jiri Olsa <[email protected]>
Acked-by Hou Tao <[email protected]>
author reviewer
#6 lore raw

PATCH 3/12 bpf: Count stats for kprobe_multi programs

In reply to Jiri Olsa

Adding support to gather stats for kprobe_multi programs.

We now count:
- missed stats due to bpf_prog_active protection (always)
- cnt/nsec of the bpf program execution (if kernel.bpf_stats_enabled=1)

Signed-off-by Jiri Olsa <[email protected]>
---
 kernel/trace/bpf_trace.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
kernel/trace/bpf_trace.c +7 -1
index a7264b2c17ad..0a8685fc1eee 100644
@@ -2706,18 +2706,24 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
 		.link = link,
 		.entry_ip = entry_ip,
 	};
+	struct bpf_prog *prog = link->link.prog;
 	struct bpf_run_ctx *old_run_ctx;
+	u64 start;
 	int err;
 
 	if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
+		bpf_prog_inc_misses_counter(prog);
 		err = 0;
 		goto out;
 	}
 
+
 	migrate_disable();
 	rcu_read_lock();
 	old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
-	err = bpf_prog_run(link->link.prog, regs);
+	start = bpf_prog_start_time();
+	err = bpf_prog_run(prog, regs);
+	bpf_prog_update_prog_stats(prog, start);
 	bpf_reset_run_ctx(old_run_ctx);
 	rcu_read_unlock();
 	migrate_enable();
Signature · 1 line
2.41.0
Acked-by on v1 3/12
#7 lore raw

Re: [PATCH bpf-next 03/12] bpf: Count stats for kprobe_multi programs

Quoted 7 lines · Jiri Olsa

Adding support to gather stats for kprobe_multi programs.

We now count:
- missed stats due to bpf_prog_active protection (always)
- cnt/nsec of the bpf program execution (if kernel.bpf_stats_enabled=1)

Signed-off-by Jiri Olsa <[email protected]>
Acked-by Hou Tao <[email protected]>

With one nit below.

Quoted 14 lines
---
 kernel/trace/bpf_trace.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
kernel/trace/bpf_trace.c +1 -0
index a7264b2c17ad..0a8685fc1eee 100644
@@ -2706,18 +2706,24 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
 		.link = link,
 		.entry_ip = entry_ip,
 	};
+	struct bpf_prog *prog = link->link.prog;
 	struct bpf_run_ctx *old_run_ctx;

kernel/trace/bpf_trace.c kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, · line 2720

Quoted 10 lines
kernel/trace/bpf_trace.c +3 -0
+	u64 start;
 	int err;
 
 	if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
+		bpf_prog_inc_misses_counter(prog);
 		err = 0;
 		goto out;
 	}
 
+

The extra empty line is not needed here.

#8 lore raw

Re: [PATCH bpf-next 03/12] bpf: Count stats for kprobe_multi programs

In reply to Jiri Olsa

Hi,

Quoted 28 lines · Jiri Olsa

Adding support to gather stats for kprobe_multi programs.

We now count:
- missed stats due to bpf_prog_active protection (always)
- cnt/nsec of the bpf program execution (if kernel.bpf_stats_enabled=1)

Signed-off-by Jiri Olsa <[email protected]>
---
 kernel/trace/bpf_trace.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
kernel/trace/bpf_trace.c +3 -0
index a7264b2c17ad..0a8685fc1eee 100644
@@ -2706,18 +2706,24 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
 		.link = link,
 		.entry_ip = entry_ip,
 	};
+	struct bpf_prog *prog = link->link.prog;
 	struct bpf_run_ctx *old_run_ctx;
+	u64 start;
 	int err;
 
 	if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
+		bpf_prog_inc_misses_counter(prog);
 		err = 0;
 		goto out;

kernel/trace/bpf_trace.c kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, · line 2726

Quoted 10 lines
kernel/trace/bpf_trace.c +4 -1
 	}
 
+
 	migrate_disable();
 	rcu_read_lock();
 	old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
-	err = bpf_prog_run(link->link.prog, regs);
+	start = bpf_prog_start_time();
+	err = bpf_prog_run(prog, regs);
+	bpf_prog_update_prog_stats(prog, start);

Oops, I missed the bpf_prog_run() here. It seems that bpf_prog_run() has already done the accounting thing, so there is no need for double accounting.

Quoted 3 lines
kernel/trace/bpf_trace.c +0 -0
 	bpf_reset_run_ctx(old_run_ctx);
 	rcu_read_unlock();
 	migrate_enable();
#9 lore raw

Re: [PATCH bpf-next 03/12] bpf: Count stats for kprobe_multi programs

Quoted 33 lines · Hou Tao

Hi,

Quoted 30 lines · Jiri Olsa

Adding support to gather stats for kprobe_multi programs.

We now count:
- missed stats due to bpf_prog_active protection (always)
- cnt/nsec of the bpf program execution (if kernel.bpf_stats_enabled=1)

Signed-off-by Jiri Olsa <[email protected]>
---
 kernel/trace/bpf_trace.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
kernel/trace/bpf_trace.c +3 -0
index a7264b2c17ad..0a8685fc1eee 100644
@@ -2706,18 +2706,24 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
 		.link = link,
 		.entry_ip = entry_ip,
 	};
+	struct bpf_prog *prog = link->link.prog;
 	struct bpf_run_ctx *old_run_ctx;
+	u64 start;
 	int err;
 
 	if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
+		bpf_prog_inc_misses_counter(prog);
 		err = 0;
 		goto out;
 	}
Quoted 12 lines

kernel/trace/bpf_trace.c kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, · line 2726

Quoted 8 lines
kernel/trace/bpf_trace.c +4 -1
+
 	migrate_disable();
 	rcu_read_lock();
 	old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
-	err = bpf_prog_run(link->link.prog, regs);
+	start = bpf_prog_start_time();
+	err = bpf_prog_run(prog, regs);
+	bpf_prog_update_prog_stats(prog, start);

Oops, I missed the bpf_prog_run() here. It seems that bpf_prog_run() has already done the accounting thing, so there is no need for double accounting.

right, same as the other change, thanks

jirka

Quoted 4 lines
Quoted 3 lines
kernel/trace/bpf_trace.c +0 -0
 	bpf_reset_run_ctx(old_run_ctx);
 	rcu_read_unlock();
 	migrate_enable();
author reviewer
#10 lore raw

PATCH 4/12 bpf: Add missed value to kprobe_multi link info

In reply to Jiri Olsa

Add missed value to kprobe_multi link info to hold the stats of missed kprobe_multi probe.

The missed counter gets incremented when fprobe fails the recursion check or there's no rethook available for return probe. In either case the attached bpf program is not executed.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/uapi/linux/bpf.h       | 1 +
 kernel/trace/bpf_trace.c       | 1 +
 tools/include/uapi/linux/bpf.h | 1 +
 3 files changed, 3 insertions(+)
include/uapi/linux/bpf.h +1 -0
index 8790b3962e4b..b754edfb0cd7 100644
@@ -6523,6 +6523,7 @@ struct bpf_link_info {
 			__aligned_u64 addrs;
 			__u32 count; /* in/out: kprobe_multi function count */
 			__u32 flags;
+			__u64 missed;
 		} kprobe_multi;
 		struct {
 			__u32 type; /* enum bpf_perf_event_type */
kernel/trace/bpf_trace.c +1 -0
index 0a8685fc1eee..0eaec3c4a5fd 100644
@@ -2614,6 +2614,7 @@ static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
 	kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link);
 	info->kprobe_multi.count = kmulti_link->cnt;
 	info->kprobe_multi.flags = kmulti_link->flags;
+	info->kprobe_multi.missed = kmulti_link->fp.nmissed;
 
 	if (!uaddrs)
 		return 0;
tools/include/uapi/linux/bpf.h +1 -0
index 8790b3962e4b..b754edfb0cd7 100644
@@ -6523,6 +6523,7 @@ struct bpf_link_info {
 			__aligned_u64 addrs;
 			__u32 count; /* in/out: kprobe_multi function count */
 			__u32 flags;
+			__u64 missed;
 		} kprobe_multi;
 		struct {
 			__u32 type; /* enum bpf_perf_event_type */
Signature · 1 line
2.41.0
Acked-by on v1 4/12
#11 lore raw

Re: [PATCH bpf-next 04/12] bpf: Add missed value to kprobe_multi link info

Quoted 8 lines · Jiri Olsa

Add missed value to kprobe_multi link info to hold the stats of missed kprobe_multi probe.

The missed counter gets incremented when fprobe fails the recursion check or there's no rethook available for return probe. In either case the attached bpf program is not executed.

Signed-off-by Jiri Olsa <[email protected]>
Acked-by Hou Tao <[email protected]>
author reviewer
#12 lore raw

PATCH 5/12 bpf: Add missed value to kprobe perf link info

In reply to Jiri Olsa

Add missed value to kprobe attached through perf link info to hold the stats of missed kprobe handler execution.

The kprobe's missed counter gets incremented when kprobe handler is not executed due to another kprobe running on the same cpu.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/linux/trace_events.h   |  6 ++++--
 include/uapi/linux/bpf.h       |  1 +
 kernel/bpf/syscall.c           | 14 ++++++++------
 kernel/trace/bpf_trace.c       |  5 +++--
 kernel/trace/trace_kprobe.c    |  5 ++++-
 tools/include/uapi/linux/bpf.h |  1 +
 6 files changed, 21 insertions(+), 11 deletions(-)
include/linux/trace_events.h +4 -2
index 5b85cf18c350..3917ddcf90bf 100644
@@ -750,7 +750,8 @@ struct bpf_raw_event_map *bpf_get_raw_tracepoint(const char *name);
 void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp);
 int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
 			    u32 *fd_type, const char **buf,
-			    u64 *probe_offset, u64 *probe_addr);
+			    u64 *probe_offset, u64 *probe_addr,
+			    unsigned long *missed);
 int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);
 int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);
 #else

@@ -790,7 +791,7 @@ static inline void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
 static inline int bpf_get_perf_event_info(const struct perf_event *event,
 					  u32 *prog_id, u32 *fd_type,
 					  const char **buf, u64 *probe_offset,
-					  u64 *probe_addr)
+					  u64 *probe_addr, unsigned long *missed)
 {
 	return -EOPNOTSUPP;
 }

@@ -865,6 +866,7 @@ extern void perf_kprobe_destroy(struct perf_event *event);
 extern int bpf_get_kprobe_info(const struct perf_event *event,
 			       u32 *fd_type, const char **symbol,
 			       u64 *probe_offset, u64 *probe_addr,
+			       unsigned long *missed,
 			       bool perf_type_tracepoint);
 #endif
 #ifdef CONFIG_UPROBE_EVENTS
include/uapi/linux/bpf.h +1 -0
index b754edfb0cd7..5a39c7a13499 100644
@@ -6539,6 +6539,7 @@ struct bpf_link_info {
 					__u32 name_len;
 					__u32 offset; /* offset from func_name */
 					__u64 addr;
+					__u64 missed;
 				} kprobe; /* BPF_PERF_EVENT_KPROBE, BPF_PERF_EVENT_KRETPROBE */
 				struct {
 					__aligned_u64 tp_name;   /* in/out */
kernel/bpf/syscall.c +8 -6
index 5d39d98f5eb1..775aeb869cfb 100644
@@ -3392,7 +3392,7 @@ static void bpf_perf_link_dealloc(struct bpf_link *link)
 static int bpf_perf_link_fill_common(const struct perf_event *event,
 				     char __user *uname, u32 ulen,
 				     u64 *probe_offset, u64 *probe_addr,
-				     u32 *fd_type)
+				     u32 *fd_type, unsigned long *missed)
 {
 	const char *buf;
 	u32 prog_id;

@@ -3403,7 +3403,7 @@ static int bpf_perf_link_fill_common(const struct perf_event *event,
 		return -EINVAL;
 
 	err = bpf_get_perf_event_info(event, &prog_id, fd_type, &buf,
-				      probe_offset, probe_addr);
+				      probe_offset, probe_addr, missed);
 	if (err)
 		return err;
 	if (!uname)

@@ -3426,6 +3426,7 @@ static int bpf_perf_link_fill_common(const struct perf_event *event,
 static int bpf_perf_link_fill_kprobe(const struct perf_event *event,
 				     struct bpf_link_info *info)
 {
+	unsigned long missed;
 	char __user *uname;
 	u64 addr, offset;
 	u32 ulen, type;

@@ -3434,7 +3435,7 @@ static int bpf_perf_link_fill_kprobe(const struct perf_event *event,
 	uname = u64_to_user_ptr(info->perf_event.kprobe.func_name);
 	ulen = info->perf_event.kprobe.name_len;
 	err = bpf_perf_link_fill_common(event, uname, ulen, &offset, &addr,
-					&type);
+					&type, &missed);
 	if (err)
 		return err;
 	if (type == BPF_FD_TYPE_KRETPROBE)

@@ -3443,6 +3444,7 @@ static int bpf_perf_link_fill_kprobe(const struct perf_event *event,
 		info->perf_event.type = BPF_PERF_EVENT_KPROBE;
 
 	info->perf_event.kprobe.offset = offset;
+	info->perf_event.kprobe.missed = missed;
 	if (!kallsyms_show_value(current_cred()))
 		addr = 0;
 	info->perf_event.kprobe.addr = addr;

@@ -3462,7 +3464,7 @@ static int bpf_perf_link_fill_uprobe(const struct perf_event *event,
 	uname = u64_to_user_ptr(info->perf_event.uprobe.file_name);
 	ulen = info->perf_event.uprobe.name_len;
 	err = bpf_perf_link_fill_common(event, uname, ulen, &offset, &addr,
-					&type);
+					&type, NULL);
 	if (err)
 		return err;
 

@@ -3498,7 +3500,7 @@ static int bpf_perf_link_fill_tracepoint(const struct perf_event *event,
 	uname = u64_to_user_ptr(info->perf_event.tracepoint.tp_name);
 	ulen = info->perf_event.tracepoint.name_len;
 	info->perf_event.type = BPF_PERF_EVENT_TRACEPOINT;
-	return bpf_perf_link_fill_common(event, uname, ulen, NULL, NULL, NULL);
+	return bpf_perf_link_fill_common(event, uname, ulen, NULL, NULL, NULL, NULL);
 }
 
 static int bpf_perf_link_fill_perf_event(const struct perf_event *event,

@@ -4831,7 +4833,7 @@ static int bpf_task_fd_query(const union bpf_attr *attr,
 
 		err = bpf_get_perf_event_info(event, &prog_id, &fd_type,
 					      &buf, &probe_offset,
-					      &probe_addr);
+					      &probe_addr, NULL);
 		if (!err)
 			err = bpf_task_fd_query_copy(attr, uattr, prog_id,
 						     fd_type, buf,
kernel/trace/bpf_trace.c +3 -2
index 0eaec3c4a5fd..cde6360bf8e8 100644
@@ -2384,7 +2384,8 @@ int bpf_probe_unregister(struct bpf_raw_event_map *btp, struct bpf_prog *prog)
 
 int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
 			    u32 *fd_type, const char **buf,
-			    u64 *probe_offset, u64 *probe_addr)
+			    u64 *probe_offset, u64 *probe_addr,
+			    unsigned long *missed)
 {
 	bool is_tracepoint, is_syscall_tp;
 	struct bpf_prog *prog;

@@ -2419,7 +2420,7 @@ int bpf_get_perf_event_info(const struct perf_event *event, u32 *prog_id,
 #ifdef CONFIG_KPROBE_EVENTS
 		if (flags & TRACE_EVENT_FL_KPROBE)
 			err = bpf_get_kprobe_info(event, fd_type, buf,
-						  probe_offset, probe_addr,
+						  probe_offset, probe_addr, missed,
 						  event->attr.type == PERF_TYPE_TRACEPOINT);
 #endif
 #ifdef CONFIG_UPROBE_EVENTS
kernel/trace/trace_kprobe.c +4 -1
index 17c21c0b2dd1..998c88874507 100644
@@ -1546,7 +1546,8 @@ NOKPROBE_SYMBOL(kretprobe_perf_func);
 
 int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
 			const char **symbol, u64 *probe_offset,
-			u64 *probe_addr, bool perf_type_tracepoint)
+			u64 *probe_addr, unsigned long *missed,
+			bool perf_type_tracepoint)
 {
 	const char *pevent = trace_event_name(event->tp_event);
 	const char *group = event->tp_event->class->system;

@@ -1565,6 +1566,8 @@ int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
 	*probe_addr = kallsyms_show_value(current_cred()) ?
 		      (unsigned long)tk->rp.kp.addr : 0;
 	*symbol = tk->symbol;
+	if (missed)
+		*missed = tk->rp.kp.nmissed;
 	return 0;
 }
 #endif	/* CONFIG_PERF_EVENTS */
tools/include/uapi/linux/bpf.h +1 -0
index b754edfb0cd7..5a39c7a13499 100644
@@ -6539,6 +6539,7 @@ struct bpf_link_info {
 					__u32 name_len;
 					__u32 offset; /* offset from func_name */
 					__u64 addr;
+					__u64 missed;
 				} kprobe; /* BPF_PERF_EVENT_KPROBE, BPF_PERF_EVENT_KRETPROBE */
 				struct {
 					__aligned_u64 tp_name;   /* in/out */
Signature · 1 line
2.41.0
#13 lore raw

Re: [PATCH bpf-next 05/12] bpf: Add missed value to kprobe perf link info

Hi,

Quoted 16 lines · Jiri Olsa

Add missed value to kprobe attached through perf link info to hold the stats of missed kprobe handler execution.

The kprobe's missed counter gets incremented when kprobe handler is not executed due to another kprobe running on the same cpu.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/linux/trace_events.h   |  6 ++++--
 include/uapi/linux/bpf.h       |  1 +
 kernel/bpf/syscall.c           | 14 ++++++++------
 kernel/trace/bpf_trace.c       |  5 +++--
 kernel/trace/trace_kprobe.c    |  5 ++++-
 tools/include/uapi/linux/bpf.h |  1 +
 6 files changed, 21 insertions(+), 11 deletions(-)

SNIP

Quoted 15 lines
kernel/trace/trace_kprobe.c +2 -1
index 17c21c0b2dd1..998c88874507 100644
@@ -1546,7 +1546,8 @@ NOKPROBE_SYMBOL(kretprobe_perf_func);
 
 int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
 			const char **symbol, u64 *probe_offset,
-			u64 *probe_addr, bool perf_type_tracepoint)
+			u64 *probe_addr, unsigned long *missed,
+			bool perf_type_tracepoint)
 {
 	const char *pevent = trace_event_name(event->tp_event);
 	const char *group = event->tp_event->class->system;

kernel/trace/trace_kprobe.c int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type, · line 1570

Quoted 5 lines
kernel/trace/trace_kprobe.c +2 -0
@@ -1565,6 +1566,8 @@ int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
 	*probe_addr = kallsyms_show_value(current_cred()) ?
 		      (unsigned long)tk->rp.kp.addr : 0;
 	*symbol = tk->symbol;
+	if (missed)
+		*missed = tk->rp.kp.nmissed;

According to the implement of probes_profile_seq_show(), the missed counter for kretprobe should be tk->rp.kp.nmissed + tk->rp.nmissed. I think it would be a good idea to factor out a common helper to get the missed counter for kprobe or kretprobe.

Quoted 15 lines
kernel/trace/trace_kprobe.c +0 -0
 	return 0;
 }
 #endif	/* CONFIG_PERF_EVENTS */
tools/include/uapi/linux/bpf.h +1 -0
index b754edfb0cd7..5a39c7a13499 100644
@@ -6539,6 +6539,7 @@ struct bpf_link_info {
 					__u32 name_len;
 					__u32 offset; /* offset from func_name */
 					__u64 addr;
+					__u64 missed;
 				} kprobe; /* BPF_PERF_EVENT_KPROBE, BPF_PERF_EVENT_KRETPROBE */
 				struct {
 					__aligned_u64 tp_name;   /* in/out */
#14 lore raw

Re: [PATCH bpf-next 05/12] bpf: Add missed value to kprobe perf link info

Quoted 38 lines · Hou Tao

Hi,

Quoted 16 lines · Jiri Olsa

Add missed value to kprobe attached through perf link info to hold the stats of missed kprobe handler execution.

The kprobe's missed counter gets incremented when kprobe handler is not executed due to another kprobe running on the same cpu.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/linux/trace_events.h   |  6 ++++--
 include/uapi/linux/bpf.h       |  1 +
 kernel/bpf/syscall.c           | 14 ++++++++------
 kernel/trace/bpf_trace.c       |  5 +++--
 kernel/trace/trace_kprobe.c    |  5 ++++-
 tools/include/uapi/linux/bpf.h |  1 +
 6 files changed, 21 insertions(+), 11 deletions(-)

SNIP

Quoted 17 lines
kernel/trace/trace_kprobe.c +2 -1
index 17c21c0b2dd1..998c88874507 100644
@@ -1546,7 +1546,8 @@ NOKPROBE_SYMBOL(kretprobe_perf_func);
 
 int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
 			const char **symbol, u64 *probe_offset,
-			u64 *probe_addr, bool perf_type_tracepoint)
+			u64 *probe_addr, unsigned long *missed,
+			bool perf_type_tracepoint)
 {
 	const char *pevent = trace_event_name(event->tp_event);
 	const char *group = event->tp_event->class->system;

@@ -1565,6 +1566,8 @@ int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
 	*probe_addr = kallsyms_show_value(current_cred()) ?
 		      (unsigned long)tk->rp.kp.addr : 0;
Quoted 8 lines

kernel/trace/trace_kprobe.c int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type, · line 1570

Quoted 3 lines
kernel/trace/trace_kprobe.c +2 -0
 	*symbol = tk->symbol;
+	if (missed)
+		*missed = tk->rp.kp.nmissed;

According to the implement of probes_profile_seq_show(), the missed counter for kretprobe should be tk->rp.kp.nmissed + tk->rp.nmissed. I think it would be a good idea to factor out a common helper to get the missed counter for kprobe or kretprobe.

ok, makes sense.. will check, I was also thinking to move bpf_get_kprobe_info args into struct

jirka

Quoted 16 lines
Quoted 15 lines
kernel/trace/trace_kprobe.c +0 -0
 	return 0;
 }
 #endif	/* CONFIG_PERF_EVENTS */
tools/include/uapi/linux/bpf.h +1 -0
index b754edfb0cd7..5a39c7a13499 100644
@@ -6539,6 +6539,7 @@ struct bpf_link_info {
 					__u32 name_len;
 					__u32 offset; /* offset from func_name */
 					__u64 addr;
+					__u64 missed;
 				} kprobe; /* BPF_PERF_EVENT_KPROBE, BPF_PERF_EVENT_KRETPROBE */
 				struct {
 					__aligned_u64 tp_name;   /* in/out */
author reviewer
#15 lore raw

PATCH 6/12 bpf: Count missed stats in trace_call_bpf

In reply to Jiri Olsa

Increase misses stats in case bpf array execution is skipped because of recursion check in trace_call_bpf.

Adding bpf_prog_missed_array that increase misses counts for all bpf programs in bpf_prog_array.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/linux/bpf.h      | 16 ++++++++++++++++
 kernel/trace/bpf_trace.c |  3 +++
 2 files changed, 19 insertions(+)
include/linux/bpf.h +16 -0
index 23a73f52c7bc..71154e991730 100644
@@ -2932,6 +2932,22 @@ static inline int sock_map_bpf_prog_query(const union bpf_attr *attr,
 #endif /* CONFIG_BPF_SYSCALL */
 #endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */
 
+static __always_inline void
+bpf_prog_missed_array(const struct bpf_prog_array *array)
+{
+	const struct bpf_prog_array_item *item;
+	struct bpf_prog *prog;
+
+	if (unlikely(!array))
+		return;
+
+	item = &array->items[0];
+	while ((prog = READ_ONCE(item->prog))) {
+		bpf_prog_inc_misses_counter(prog);
+		item++;
+	}
+}
+
 #if defined(CONFIG_INET) && defined(CONFIG_BPF_SYSCALL)
 void bpf_sk_reuseport_detach(struct sock *sk);
 int bpf_fd_reuseport_array_lookup_elem(struct bpf_map *map, void *key,
kernel/trace/bpf_trace.c +3 -0
index cde6360bf8e8..7961f9d9dd13 100644
@@ -117,6 +117,9 @@ unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx)
 		 * and don't send kprobe event into ring-buffer,
 		 * so return zero here
 		 */
+		rcu_read_lock();
+		bpf_prog_missed_array(rcu_dereference(call->prog_array));
+		rcu_read_unlock();
 		ret = 0;
 		goto out;
 	}
Signature · 1 line
2.41.0
#16 lore raw

Re: [PATCH bpf-next 06/12] bpf: Count missed stats in trace_call_bpf

Quoted 18 lines · Jiri Olsa

Increase misses stats in case bpf array execution is skipped because of recursion check in trace_call_bpf.

Adding bpf_prog_missed_array that increase misses counts for all bpf programs in bpf_prog_array.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/linux/bpf.h      | 16 ++++++++++++++++
 kernel/trace/bpf_trace.c |  3 +++
 2 files changed, 19 insertions(+)
include/linux/bpf.h +0 -0
index 23a73f52c7bc..71154e991730 100644

include/linux/bpf.h static inline int sock_map_bpf_prog_query(const union bpf_attr *attr, · line 2936

Quoted 5 lines
include/linux/bpf.h +2 -0
@@ -2932,6 +2932,22 @@ static inline int sock_map_bpf_prog_query(const union bpf_attr *attr,
 #endif /* CONFIG_BPF_SYSCALL */
 #endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */
 
+static __always_inline void
+bpf_prog_missed_array(const struct bpf_prog_array *array)

The name hardly explains the purpose.
Please give it a better name.
Maybe bpf_prog_inc_misses_counters ?
Just extra "s".

#17 lore raw

Re: [PATCH bpf-next 06/12] bpf: Count missed stats in trace_call_bpf

Quoted 22 lines · Alexei Starovoitov
Quoted 21 lines · Jiri Olsa

Increase misses stats in case bpf array execution is skipped because of recursion check in trace_call_bpf.

Adding bpf_prog_missed_array that increase misses counts for all bpf programs in bpf_prog_array.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/linux/bpf.h      | 16 ++++++++++++++++
 kernel/trace/bpf_trace.c |  3 +++
 2 files changed, 19 insertions(+)
include/linux/bpf.h +0 -0
index 23a73f52c7bc..71154e991730 100644
@@ -2932,6 +2932,22 @@ static inline int sock_map_bpf_prog_query(const union bpf_attr *attr,
 #endif /* CONFIG_BPF_SYSCALL */
 #endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */
Quoted 7 lines

include/linux/bpf.h static inline int sock_map_bpf_prog_query(const union bpf_attr *attr, · line 2936

Quoted 2 lines
include/linux/bpf.h +2 -0
+static __always_inline void
+bpf_prog_missed_array(const struct bpf_prog_array *array)

The name hardly explains the purpose.
Please give it a better name.
Maybe bpf_prog_inc_misses_counters ?
Just extra "s".

I thought making it similar to bpf_prog_run_array, but bpf_prog_inc_misses_counters sounds better

thanks,
jirka

author reviewer
#18 lore raw

PATCH 7/12 bpf: Move bpf_prog_run_array down in the header file

In reply to Jiri Olsa

Moving bpf_prog_run_array down in the header file so we can easily use bpf_prog_start_time and bpf_prog_update_prog_stats functions in bpf_prog_run_array in following change.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/linux/bpf.h | 60 ++++++++++++++++++++++-----------------------
 1 file changed, 30 insertions(+), 30 deletions(-)
include/linux/bpf.h +30 -30
index 71154e991730..478fdc4794c9 100644
@@ -1904,36 +1904,6 @@ static inline void bpf_reset_run_ctx(struct bpf_run_ctx *old_ctx)
 
 typedef u32 (*bpf_prog_run_fn)(const struct bpf_prog *prog, const void *ctx);
 
-static __always_inline u32
-bpf_prog_run_array(const struct bpf_prog_array *array,
-		   const void *ctx, bpf_prog_run_fn run_prog)
-{
-	const struct bpf_prog_array_item *item;
-	const struct bpf_prog *prog;
-	struct bpf_run_ctx *old_run_ctx;
-	struct bpf_trace_run_ctx run_ctx;
-	u32 ret = 1;
-
-	RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "no rcu lock held");
-
-	if (unlikely(!array))
-		return ret;
-
-	run_ctx.is_uprobe = false;
-
-	migrate_disable();
-	old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
-	item = &array->items[0];
-	while ((prog = READ_ONCE(item->prog))) {
-		run_ctx.bpf_cookie = item->bpf_cookie;
-		ret &= run_prog(prog, ctx);
-		item++;
-	}
-	bpf_reset_run_ctx(old_run_ctx);
-	migrate_enable();
-	return ret;
-}
-
 /* Notes on RCU design for bpf_prog_arrays containing sleepable programs:
  *
  * We use the tasks_trace rcu flavor read section to protect the bpf_prog_array

@@ -2740,6 +2710,36 @@ static inline void bpf_dynptr_set_rdonly(struct bpf_dynptr_kern *ptr)
 }
 #endif /* CONFIG_BPF_SYSCALL */
 
+static __always_inline u32
+bpf_prog_run_array(const struct bpf_prog_array *array,
+		   const void *ctx, bpf_prog_run_fn run_prog)
+{
+	const struct bpf_prog_array_item *item;
+	const struct bpf_prog *prog;
+	struct bpf_run_ctx *old_run_ctx;
+	struct bpf_trace_run_ctx run_ctx;
+	u32 ret = 1;
+
+	RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "no rcu lock held");
+
+	if (unlikely(!array))
+		return ret;
+
+	run_ctx.is_uprobe = false;
+
+	migrate_disable();
+	old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
+	item = &array->items[0];
+	while ((prog = READ_ONCE(item->prog))) {
+		run_ctx.bpf_cookie = item->bpf_cookie;
+		ret &= run_prog(prog, ctx);
+		item++;
+	}
+	bpf_reset_run_ctx(old_run_ctx);
+	migrate_enable();
+	return ret;
+}
+
 static __always_inline int
 bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr)
 {
Signature · 1 line
2.41.0
author reviewer
#19 lore raw

PATCH 8/12 bpf: Count run stats in bpf_prog_run_array

In reply to Jiri Olsa

Count runtime stats for bf programs executed through bpf_prog_run_array function. That covers kprobe, perf event and trace syscall probe.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/linux/bpf.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
include/linux/bpf.h +4 -1
index 478fdc4794c9..732253eea675 100644
@@ -2715,10 +2715,11 @@ bpf_prog_run_array(const struct bpf_prog_array *array,
 		   const void *ctx, bpf_prog_run_fn run_prog)
 {
 	const struct bpf_prog_array_item *item;
-	const struct bpf_prog *prog;
+	struct bpf_prog *prog;
 	struct bpf_run_ctx *old_run_ctx;
 	struct bpf_trace_run_ctx run_ctx;
 	u32 ret = 1;
+	u64 start;
 
 	RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "no rcu lock held");
 

@@ -2732,7 +2733,9 @@ bpf_prog_run_array(const struct bpf_prog_array *array,
 	item = &array->items[0];
 	while ((prog = READ_ONCE(item->prog))) {
 		run_ctx.bpf_cookie = item->bpf_cookie;
+		start = bpf_prog_start_time();
 		ret &= run_prog(prog, ctx);
+		bpf_prog_update_prog_stats(prog, start);
 		item++;
 	}
 	bpf_reset_run_ctx(old_run_ctx);
Signature · 1 line
2.41.0
#20 lore raw

Re: [PATCH bpf-next 08/12] bpf: Count run stats in bpf_prog_run_array

Hi,

Quoted 26 lines · Jiri Olsa

Count runtime stats for bf programs executed through bpf_prog_run_array function. That covers kprobe, perf event and trace syscall probe.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/linux/bpf.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
include/linux/bpf.h +2 -1
index 478fdc4794c9..732253eea675 100644
@@ -2715,10 +2715,11 @@ bpf_prog_run_array(const struct bpf_prog_array *array,
 		   const void *ctx, bpf_prog_run_fn run_prog)
 {
 	const struct bpf_prog_array_item *item;
-	const struct bpf_prog *prog;
+	struct bpf_prog *prog;
 	struct bpf_run_ctx *old_run_ctx;
 	struct bpf_trace_run_ctx run_ctx;
 	u32 ret = 1;
+	u64 start;
 
 	RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "no rcu lock held");

include/linux/bpf.h bpf_prog_run_array(const struct bpf_prog_array *array, · line 2740

Quoted 8 lines
include/linux/bpf.h +2 -0
@@ -2732,7 +2733,9 @@ bpf_prog_run_array(const struct bpf_prog_array *array,
 	item = &array->items[0];
 	while ((prog = READ_ONCE(item->prog))) {
 		run_ctx.bpf_cookie = item->bpf_cookie;
+		start = bpf_prog_start_time();
 		ret &= run_prog(prog, ctx);
+		bpf_prog_update_prog_stats(prog, start);
 		item++;
 	}

bpf_prog_run() has already accounted the running count and the consumed time for the prog, so I think both previous patch and this patch are not needed.

Quoted 1 line
include/linux/bpf.h +0 -0
 	bpf_reset_run_ctx(old_run_ctx);
#21 lore raw

Re: [PATCH bpf-next 08/12] bpf: Count run stats in bpf_prog_run_array

Quoted 28 lines · Hou Tao

Hi,

Quoted 25 lines · Jiri Olsa

Count runtime stats for bf programs executed through bpf_prog_run_array function. That covers kprobe, perf event and trace syscall probe.

Signed-off-by Jiri Olsa <[email protected]>
---
 include/linux/bpf.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
include/linux/bpf.h +2 -1
index 478fdc4794c9..732253eea675 100644
@@ -2715,10 +2715,11 @@ bpf_prog_run_array(const struct bpf_prog_array *array,
 		   const void *ctx, bpf_prog_run_fn run_prog)
 {
 	const struct bpf_prog_array_item *item;
-	const struct bpf_prog *prog;
+	struct bpf_prog *prog;
 	struct bpf_run_ctx *old_run_ctx;
 	struct bpf_trace_run_ctx run_ctx;
 	u32 ret = 1;
+	u64 start;
 
 	RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "no rcu lock held");
Quoted 13 lines

include/linux/bpf.h bpf_prog_run_array(const struct bpf_prog_array *array, · line 2740

Quoted 9 lines
include/linux/bpf.h +2 -0
@@ -2732,7 +2733,9 @@ bpf_prog_run_array(const struct bpf_prog_array *array,
 	item = &array->items[0];
 	while ((prog = READ_ONCE(item->prog))) {
 		run_ctx.bpf_cookie = item->bpf_cookie;
+		start = bpf_prog_start_time();
 		ret &= run_prog(prog, ctx);
+		bpf_prog_update_prog_stats(prog, start);
 		item++;
 	}

bpf_prog_run() has already accounted the running count and the consumed time for the prog, so I think both previous patch and this patch are not needed.

ugh right, I missed that.. thanks

jirka

Quoted 3 lines
Quoted 2 lines
include/linux/bpf.h +0 -0
 	bpf_reset_run_ctx(old_run_ctx);
author reviewer
#22 lore raw

PATCH 9/12 bpftool: Display missed count for kprobe_multi link

In reply to Jiri Olsa

Adding 'missed' field to display missed counts for kprobes attached by kprobe multi link, like:

  # bpftool link
  5: kprobe_multi  prog 76
          kprobe.multi  func_cnt 1 missed 1
          addr             func [module]
          ffffffffa039c030 fp3_test [fprobe_test]
  # bpftool link -jp
  [{
          "id": 5,
          "type": "kprobe_multi",
          "prog_id": 76,
          "retprobe": false,
          "func_cnt": 1,
          "missed": 1,
          "funcs": [{
                  "addr": 18446744072102723632,
                  "func": "fp3_test",
                  "module": "fprobe_test"
              }
          ]
      }
  ]
Signed-off-by Jiri Olsa <[email protected]>
---
 tools/bpf/bpftool/link.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
tools/bpf/bpftool/link.c +4 -1
index 0b214f6ab5c8..7387e51a5e5c 100644
@@ -265,6 +265,7 @@ show_kprobe_multi_json(struct bpf_link_info *info, json_writer_t *wtr)
 	jsonw_bool_field(json_wtr, "retprobe",
 			 info->kprobe_multi.flags & BPF_F_KPROBE_MULTI_RETURN);
 	jsonw_uint_field(json_wtr, "func_cnt", info->kprobe_multi.count);
+	jsonw_uint_field(json_wtr, "missed", info->kprobe_multi.missed);
 	jsonw_name(json_wtr, "funcs");
 	jsonw_start_array(json_wtr);
 	addrs = u64_to_ptr(info->kprobe_multi.addrs);

@@ -640,7 +641,9 @@ static void show_kprobe_multi_plain(struct bpf_link_info *info)
 		printf("\n\tkretprobe.multi  ");
 	else
 		printf("\n\tkprobe.multi  ");
-	printf("func_cnt %u  ", info->kprobe_multi.count);
+	printf("func_cnt %u", info->kprobe_multi.count);
+	if (info->kprobe_multi.missed)
+		printf(" missed %llu", info->kprobe_multi.missed);
 	addrs = (__u64 *)u64_to_ptr(info->kprobe_multi.addrs);
 	qsort(addrs, info->kprobe_multi.count, sizeof(__u64), cmp_u64);
Signature · 1 line
2.41.0
Reviewed-by on v1 9/12
#23 lore raw

Re: [PATCH bpf-next 09/12] bpftool: Display missed count for kprobe_multi link

Quoted 44 lines · Jiri Olsa

Adding 'missed' field to display missed counts for kprobes attached by kprobe multi link, like:

  # bpftool link
  5: kprobe_multi  prog 76
          kprobe.multi  func_cnt 1 missed 1
          addr             func [module]
          ffffffffa039c030 fp3_test [fprobe_test]
  # bpftool link -jp
  [{
          "id": 5,
          "type": "kprobe_multi",
          "prog_id": 76,
          "retprobe": false,
          "func_cnt": 1,
          "missed": 1,
          "funcs": [{
                  "addr": 18446744072102723632,
                  "func": "fp3_test",
                  "module": "fprobe_test"
              }
          ]
      }
  ]
Signed-off-by Jiri Olsa <[email protected]>
---
 tools/bpf/bpftool/link.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
tools/bpf/bpftool/link.c +1 -0
index 0b214f6ab5c8..7387e51a5e5c 100644
@@ -265,6 +265,7 @@ show_kprobe_multi_json(struct bpf_link_info *info, json_writer_t *wtr)
 	jsonw_bool_field(json_wtr, "retprobe",
 			 info->kprobe_multi.flags & BPF_F_KPROBE_MULTI_RETURN);
 	jsonw_uint_field(json_wtr, "func_cnt", info->kprobe_multi.count);
+	jsonw_uint_field(json_wtr, "missed", info->kprobe_multi.missed);
 	jsonw_name(json_wtr, "funcs");
 	jsonw_start_array(json_wtr);
 	addrs = u64_to_ptr(info->kprobe_multi.addrs);

tools/bpf/bpftool/link.c static void show_kprobe_multi_plain(struct bpf_link_info *info) · line 646

Quoted 7 lines
tools/bpf/bpftool/link.c +3 -1
@@ -640,7 +641,9 @@ static void show_kprobe_multi_plain(struct bpf_link_info *info)
 		printf("\n\tkretprobe.multi  ");
 	else
 		printf("\n\tkprobe.multi  ");
-	printf("func_cnt %u  ", info->kprobe_multi.count);
+	printf("func_cnt %u", info->kprobe_multi.count);
+	if (info->kprobe_multi.missed)
+		printf(" missed %llu", info->kprobe_multi.missed);

Nit: If you respin, please conserve the double space at the beginning of " missed %llu", to visually help separate from the previous field in the plain output.

Looks good otherwise, thanks!

Reviewed-by Quentin Monnet <[email protected]>
Quoted 3 lines
tools/bpf/bpftool/link.c +0 -0
 	addrs = (__u64 *)u64_to_ptr(info->kprobe_multi.addrs);
 	qsort(addrs, info->kprobe_multi.count, sizeof(__u64), cmp_u64);
#24 lore raw

Re: [PATCH bpf-next 09/12] bpftool: Display missed count for kprobe_multi link

Quoted 48 lines · Quentin Monnet
Quoted 47 lines · Jiri Olsa

Adding 'missed' field to display missed counts for kprobes attached by kprobe multi link, like:

  # bpftool link
  5: kprobe_multi  prog 76
          kprobe.multi  func_cnt 1 missed 1
          addr             func [module]
          ffffffffa039c030 fp3_test [fprobe_test]
  # bpftool link -jp
  [{
          "id": 5,
          "type": "kprobe_multi",
          "prog_id": 76,
          "retprobe": false,
          "func_cnt": 1,
          "missed": 1,
          "funcs": [{
                  "addr": 18446744072102723632,
                  "func": "fp3_test",
                  "module": "fprobe_test"
              }
          ]
      }
  ]
Signed-off-by Jiri Olsa <[email protected]>
---
 tools/bpf/bpftool/link.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
tools/bpf/bpftool/link.c +1 -0
index 0b214f6ab5c8..7387e51a5e5c 100644
@@ -265,6 +265,7 @@ show_kprobe_multi_json(struct bpf_link_info *info, json_writer_t *wtr)
 	jsonw_bool_field(json_wtr, "retprobe",
 			 info->kprobe_multi.flags & BPF_F_KPROBE_MULTI_RETURN);
 	jsonw_uint_field(json_wtr, "func_cnt", info->kprobe_multi.count);
+	jsonw_uint_field(json_wtr, "missed", info->kprobe_multi.missed);
 	jsonw_name(json_wtr, "funcs");
 	jsonw_start_array(json_wtr);
 	addrs = u64_to_ptr(info->kprobe_multi.addrs);

@@ -640,7 +641,9 @@ static void show_kprobe_multi_plain(struct bpf_link_info *info)
 		printf("\n\tkretprobe.multi  ");
 	else
 		printf("\n\tkprobe.multi  ");
Quoted 8 lines

tools/bpf/bpftool/link.c static void show_kprobe_multi_plain(struct bpf_link_info *info) · line 646

Quoted 4 lines
tools/bpf/bpftool/link.c +3 -1
-	printf("func_cnt %u  ", info->kprobe_multi.count);
+	printf("func_cnt %u", info->kprobe_multi.count);
+	if (info->kprobe_multi.missed)
+		printf(" missed %llu", info->kprobe_multi.missed);

Nit: If you respin, please conserve the double space at the beginning of " missed %llu", to visually help separate from the previous field in the plain output.

right, will fix that

Quoted 4 lines

Looks good otherwise, thanks!

Reviewed-by Quentin Monnet <[email protected]>

thanks,
jirka

Quoted 5 lines
Quoted 4 lines
tools/bpf/bpftool/link.c +0 -0
 	addrs = (__u64 *)u64_to_ptr(info->kprobe_multi.addrs);
 	qsort(addrs, info->kprobe_multi.count, sizeof(__u64), cmp_u64);
author reviewer
#25 lore raw

PATCH 10/12 bpftool: Display missed count for kprobe perf link

In reply to Jiri Olsa

Adding 'missed' field to display missed counts for kprobes attached by perf event link, like:

  # bpftool link
  5: perf_event  prog 82
          kprobe ffffffff815203e0 ksys_write
  6: perf_event  prog 83
          kprobe ffffffff811d1e50 scheduler_tick missed 682217
  # bpftool link -jp
  [{
          "id": 5,
          "type": "perf_event",
          "prog_id": 82,
          "retprobe": false,
          "addr": 18446744071584220128,
          "func": "ksys_write",
          "offset": 0,
          "missed": 0
      },{
          "id": 6,
          "type": "perf_event",
          "prog_id": 83,
          "retprobe": false,
          "addr": 18446744071580753488,
          "func": "scheduler_tick",
          "offset": 0,
          "missed": 693469
      }
  ]
Signed-off-by Jiri Olsa <[email protected]>
---
 tools/bpf/bpftool/link.c | 3 +++
 1 file changed, 3 insertions(+)
tools/bpf/bpftool/link.c +3 -0
index 7387e51a5e5c..d65129318f82 100644
@@ -302,6 +302,7 @@ show_perf_event_kprobe_json(struct bpf_link_info *info, json_writer_t *wtr)
 	jsonw_string_field(wtr, "func",
 			   u64_to_ptr(info->perf_event.kprobe.func_name));
 	jsonw_uint_field(wtr, "offset", info->perf_event.kprobe.offset);
+	jsonw_uint_field(wtr, "missed", info->perf_event.kprobe.missed);
 }
 
 static void

@@ -686,6 +687,8 @@ static void show_perf_event_kprobe_plain(struct bpf_link_info *info)
 	printf("%s", buf);
 	if (info->perf_event.kprobe.offset)
 		printf("+%#x", info->perf_event.kprobe.offset);
+	if (info->perf_event.kprobe.missed)
+		printf(" missed %llu", info->perf_event.kprobe.missed);
 	printf("  ");
 }
Signature · 1 line
2.41.0
Reviewed-by on v1 10/12
#26 lore raw

Re: [PATCH bpf-next 10/12] bpftool: Display missed count for kprobe perf link

Quoted 49 lines · Jiri Olsa

Adding 'missed' field to display missed counts for kprobes attached by perf event link, like:

  # bpftool link
  5: perf_event  prog 82
          kprobe ffffffff815203e0 ksys_write
  6: perf_event  prog 83
          kprobe ffffffff811d1e50 scheduler_tick missed 682217
  # bpftool link -jp
  [{
          "id": 5,
          "type": "perf_event",
          "prog_id": 82,
          "retprobe": false,
          "addr": 18446744071584220128,
          "func": "ksys_write",
          "offset": 0,
          "missed": 0
      },{
          "id": 6,
          "type": "perf_event",
          "prog_id": 83,
          "retprobe": false,
          "addr": 18446744071580753488,
          "func": "scheduler_tick",
          "offset": 0,
          "missed": 693469
      }
  ]
Signed-off-by Jiri Olsa <[email protected]>
---
 tools/bpf/bpftool/link.c | 3 +++
 1 file changed, 3 insertions(+)
tools/bpf/bpftool/link.c +1 -0
index 7387e51a5e5c..d65129318f82 100644
@@ -302,6 +302,7 @@ show_perf_event_kprobe_json(struct bpf_link_info *info, json_writer_t *wtr)
 	jsonw_string_field(wtr, "func",
 			   u64_to_ptr(info->perf_event.kprobe.func_name));
 	jsonw_uint_field(wtr, "offset", info->perf_event.kprobe.offset);
+	jsonw_uint_field(wtr, "missed", info->perf_event.kprobe.missed);
 }
 
 static void

tools/bpf/bpftool/link.c static void show_perf_event_kprobe_plain(struct bpf_link_info *info) · line 694

Quoted 8 lines
tools/bpf/bpftool/link.c +2 -0
@@ -686,6 +687,8 @@ static void show_perf_event_kprobe_plain(struct bpf_link_info *info)
 	printf("%s", buf);
 	if (info->perf_event.kprobe.offset)
 		printf("+%#x", info->perf_event.kprobe.offset);
+	if (info->perf_event.kprobe.missed)
+		printf(" missed %llu", info->perf_event.kprobe.missed);
 	printf("  ");
 }

Same comment as for the previous patch: double space between fields in plain output please. Thanks!

Reviewed-by Quentin Monnet <[email protected]>
#27 lore raw

Re: [PATCH bpf-next 10/12] bpftool: Display missed count for kprobe perf link

Quoted 62 lines · Quentin Monnet
Quoted 49 lines · Jiri Olsa

Adding 'missed' field to display missed counts for kprobes attached by perf event link, like:

  # bpftool link
  5: perf_event  prog 82
          kprobe ffffffff815203e0 ksys_write
  6: perf_event  prog 83
          kprobe ffffffff811d1e50 scheduler_tick missed 682217
  # bpftool link -jp
  [{
          "id": 5,
          "type": "perf_event",
          "prog_id": 82,
          "retprobe": false,
          "addr": 18446744071584220128,
          "func": "ksys_write",
          "offset": 0,
          "missed": 0
      },{
          "id": 6,
          "type": "perf_event",
          "prog_id": 83,
          "retprobe": false,
          "addr": 18446744071580753488,
          "func": "scheduler_tick",
          "offset": 0,
          "missed": 693469
      }
  ]
Signed-off-by Jiri Olsa <[email protected]>
---
 tools/bpf/bpftool/link.c | 3 +++
 1 file changed, 3 insertions(+)
tools/bpf/bpftool/link.c +1 -0
index 7387e51a5e5c..d65129318f82 100644
@@ -302,6 +302,7 @@ show_perf_event_kprobe_json(struct bpf_link_info *info, json_writer_t *wtr)
 	jsonw_string_field(wtr, "func",
 			   u64_to_ptr(info->perf_event.kprobe.func_name));
 	jsonw_uint_field(wtr, "offset", info->perf_event.kprobe.offset);
+	jsonw_uint_field(wtr, "missed", info->perf_event.kprobe.missed);
 }
 
 static void

tools/bpf/bpftool/link.c static void show_perf_event_kprobe_plain(struct bpf_link_info *info) · line 694

Quoted 8 lines
tools/bpf/bpftool/link.c +2 -0
@@ -686,6 +687,8 @@ static void show_perf_event_kprobe_plain(struct bpf_link_info *info)
 	printf("%s", buf);
 	if (info->perf_event.kprobe.offset)
 		printf("+%#x", info->perf_event.kprobe.offset);
+	if (info->perf_event.kprobe.missed)
+		printf(" missed %llu", info->perf_event.kprobe.missed);
 	printf("  ");
 }

Same comment as for the previous patch: double space between fields in plain output please. Thanks!

Quoted 1 line
Reviewed-by Quentin Monnet <[email protected]>

will fix, thanks

jirka

author reviewer
#28 lore raw

PATCH 11/12 selftests/bpf: Add test missed counts of perf event link kprobe

In reply to Jiri Olsa

Adding test that puts kprobe on bpf_fentry_test1 that calls bpf_kfunc_common_test kfunc, which has also kprobe on.

The latter won't get triggered due to kprobe recursion check and kprobe missed counter is incremented.

Signed-off-by Jiri Olsa <[email protected]>
---
 .../selftests/bpf/bpf_testmod/bpf_testmod.c   |  5 ++
 .../bpf/bpf_testmod/bpf_testmod_kfunc.h       |  2 +
 .../testing/selftests/bpf/prog_tests/missed.c | 47 +++++++++++++++++++
 .../selftests/bpf/progs/missed_kprobe.c       | 30 ++++++++++++
 4 files changed, 84 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/missed.c
 create mode 100644 tools/testing/selftests/bpf/progs/missed_kprobe.c
tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c +5 -0
index cefc5dd72573..a5e246f7b202 100644
@@ -138,6 +138,10 @@ __bpf_kfunc void bpf_iter_testmod_seq_destroy(struct bpf_iter_testmod_seq *it)
 	it->cnt = 0;
 }
 
+__bpf_kfunc void bpf_kfunc_common_test(void)
+{
+}
+
 struct bpf_testmod_btf_type_tag_1 {
 	int a;
 };

@@ -343,6 +347,7 @@ BTF_SET8_START(bpf_testmod_common_kfunc_ids)
 BTF_ID_FLAGS(func, bpf_iter_testmod_seq_new, KF_ITER_NEW)
 BTF_ID_FLAGS(func, bpf_iter_testmod_seq_next, KF_ITER_NEXT | KF_RET_NULL)
 BTF_ID_FLAGS(func, bpf_iter_testmod_seq_destroy, KF_ITER_DESTROY)
+BTF_ID_FLAGS(func, bpf_kfunc_common_test)
 BTF_SET8_END(bpf_testmod_common_kfunc_ids)
 
 static const struct btf_kfunc_id_set bpf_testmod_common_kfunc_set = {
tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h +2 -0
index f5c5b1375c24..7c664dd61059 100644
@@ -104,4 +104,6 @@ void bpf_kfunc_call_test_fail1(struct prog_test_fail1 *p);
 void bpf_kfunc_call_test_fail2(struct prog_test_fail2 *p);
 void bpf_kfunc_call_test_fail3(struct prog_test_fail3 *p);
 void bpf_kfunc_call_test_mem_len_fail1(void *mem, int len);
+
+void bpf_kfunc_common_test(void) __ksym;
 #endif /* _BPF_TESTMOD_KFUNC_H */
tools/testing/selftests/bpf/prog_tests/missed.c new file +47 -0

47 lines not on this page · raw message

tools/testing/selftests/bpf/progs/missed_kprobe.c new file +30 -0
new file mode 100644
index 000000000000..7f9ef701f5de
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "../bpf_testmod/bpf_testmod_kfunc.h"
+
+char _license[] SEC("license") = "GPL";
+
+/*
+ * No tests in here, just to trigger 'bpf_fentry_test*'
+ * through tracing test_run
+ */
+SEC("fentry/bpf_modify_return_test")
+int BPF_PROG(trigger)
+{
+	return 0;
+}
+
+SEC("kprobe/bpf_fentry_test1")
+int test1(struct pt_regs *ctx)
+{
+	bpf_kfunc_common_test();
+	return 0;
+}
+
+SEC("kprobe/bpf_kfunc_common_test")
+int test2(struct pt_regs *ctx)
+{
+	return 0;
+}
Signature · 1 line
2.41.0
Acked-by on v1 11/12
#29 lore raw

Re: [PATCH bpf-next 11/12] selftests/bpf: Add test missed counts of perf event link kprobe

Quoted 7 lines · Jiri Olsa

Adding test that puts kprobe on bpf_fentry_test1 that calls bpf_kfunc_common_test kfunc, which has also kprobe on.

The latter won't get triggered due to kprobe recursion check and kprobe missed counter is incremented.

Signed-off-by Jiri Olsa <[email protected]>
Acked-by Hou Tao <[email protected]>
author reviewer
#30 lore raw

PATCH 12/12 selftests/bpf: Add test recursion stats of perf event link kprobe

In reply to Jiri Olsa

Adding selftest that puts kprobe.multi on bpf_fentry_test1 that calls bpf_kfunc_common_test kfunc which has 3 perf event kprobes and 1 kprobe.multi attached.

Because fprobe (kprobe.multi attach layear) does not have strict recursion check the kprobe's bpf_prog_active check is hit for test2-5.

Disabling this test for arm64, because there's no fprobe support yet.

Signed-off-by Jiri Olsa <[email protected]>
---
 tools/testing/selftests/bpf/DENYLIST.aarch64  |  1 +
 .../testing/selftests/bpf/prog_tests/missed.c | 50 +++++++++++++++++++
 .../bpf/progs/missed_kprobe_recursion.c       | 48 ++++++++++++++++++
 3 files changed, 99 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c
tools/testing/selftests/bpf/DENYLIST.aarch64 +1 -0
index 7f768d335698..3f2187c049db 100644
@@ -15,3 +15,4 @@ fexit_test/fexit_many_args                       # fexit_many_args:FAIL:fexit_ma
 fill_link_info/kprobe_multi_link_info            # bpf_program__attach_kprobe_multi_opts unexpected error: -95
 fill_link_info/kretprobe_multi_link_info         # bpf_program__attach_kprobe_multi_opts unexpected error: -95
 fill_link_info/kprobe_multi_invalid_ubuff        # bpf_program__attach_kprobe_multi_opts unexpected error: -95
+missed/kprobe_recursion                          # missed_kprobe_recursion__attach unexpected error: -95 (errno 95)
tools/testing/selftests/bpf/prog_tests/missed.c +50 -0

64 lines not on this page · raw message

tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c new file +48 -0

48 lines not on this page · raw message

Signature · 1 line
2.41.0
Acked-by on v1 12/12
#31 lore raw

Re: [PATCH bpf-next 12/12] selftests/bpf: Add test recursion stats of perf event link kprobe

Quoted 10 lines · Jiri Olsa

Adding selftest that puts kprobe.multi on bpf_fentry_test1 that calls bpf_kfunc_common_test kfunc which has 3 perf event kprobes and 1 kprobe.multi attached.

Because fprobe (kprobe.multi attach layear) does not have strict recursion check the kprobe's bpf_prog_active check is hit for test2-5.

Disabling this test for arm64, because there's no fprobe support yet.

Signed-off-by Jiri Olsa <[email protected]>
Acked-by Hou Tao <[email protected]>
#32 lore raw
In reply to Jiri Olsa

Hi,

Quoted 9 lines · Jiri Olsa

hi,
at the moment we can't retrieve the number of missed kprobe executions and subsequent execution of BPF programs.

This patchset adds:
- counting of missed execution on attach layer for:
. kprobes attached through perf link (kprobe/ftrace) . kprobes attached through kprobe.multi link (fprobe)
- counting of recursion_misses for BPF kprobe programs

Because trace_call_bpf() is used for both kprobe and trace-point bpf program, so I think it is better to add one selftest for missed counter for trace-point program as well.

Quoted 55 lines

- counting runtime stats (kernel.bpf_stats_enabled=1) for BPF programs executed through bpf_prog_run_array - kprobes, perf events, trace syscall probes

It's still technically possible to create kprobe without perf link (using SET_BPF perf ioctl) in which case we don't have a way to retrieve the kprobe's 'missed' count. However both libbpf and cilium/ebpf libraries use perf link if it's available, and for old kernels without perf link support we can use BPF program to retrieve the kprobe missed count.

Also available at:
https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
bpf/missed_stats

thanks,
jirka

---
Jiri Olsa (12):
bpf: Move update_prog_stats to syscall object
bpf: Move bpf_prog_start_time to linux/filter.h
bpf: Count stats for kprobe_multi programs
bpf: Add missed value to kprobe_multi link info
bpf: Add missed value to kprobe perf link info
bpf: Count missed stats in trace_call_bpf
bpf: Move bpf_prog_run_array down in the header file
bpf: Count run stats in bpf_prog_run_array
bpftool: Display missed count for kprobe_multi link
bpftool: Display missed count for kprobe perf link selftests/bpf: Add test missed counts of perf event link kprobe elftests/bpf: Add test recursion stats of perf event link kprobe

 include/linux/bpf.h                                         | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------------------------
 include/linux/trace_events.h                                |   6 ++++--
 include/uapi/linux/bpf.h                                    |   2 ++
 kernel/bpf/syscall.c                                        |  36 +++++++++++++++++++++++++------
 kernel/bpf/trampoline.c                                     |  45 +++++----------------------------------
 kernel/trace/bpf_trace.c                                    |  17 ++++++++++++---
 kernel/trace/trace_kprobe.c                                 |   5 ++++-
 tools/bpf/bpftool/link.c                                    |   8 ++++++-
 tools/include/uapi/linux/bpf.h                              |   2 ++
 tools/testing/selftests/bpf/DENYLIST.aarch64                |   1 +
 tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c       |   5 +++++
 tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h |   2 ++
 tools/testing/selftests/bpf/prog_tests/missed.c             |  97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/missed_kprobe.c           |  30 ++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c |  48 +++++++++++++++++++++++++++++++++++++++++
 15 files changed, 327 insertions(+), 83 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/missed.c
 create mode 100644 tools/testing/selftests/bpf/progs/missed_kprobe.c
 create mode 100644 tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c

.

#33 lore raw
Quoted 13 lines · Hou Tao

Hi,

Quoted 9 lines · Jiri Olsa

hi,
at the moment we can't retrieve the number of missed kprobe executions and subsequent execution of BPF programs.

This patchset adds:
- counting of missed execution on attach layer for:
. kprobes attached through perf link (kprobe/ftrace) . kprobes attached through kprobe.multi link (fprobe)
- counting of recursion_misses for BPF kprobe programs

Quoted 3 lines

Because trace_call_bpf() is used for both kprobe and trace-point bpf program, so I think it is better to add one selftest for missed counter for trace-point program as well.

ok, will try to add some

thanks,
jirka

Quoted 56 lines
Quoted 55 lines

- counting runtime stats (kernel.bpf_stats_enabled=1) for BPF programs executed through bpf_prog_run_array - kprobes, perf events, trace syscall probes

It's still technically possible to create kprobe without perf link (using SET_BPF perf ioctl) in which case we don't have a way to retrieve the kprobe's 'missed' count. However both libbpf and cilium/ebpf libraries use perf link if it's available, and for old kernels without perf link support we can use BPF program to retrieve the kprobe missed count.

Also available at:
https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
bpf/missed_stats

thanks,
jirka

---
Jiri Olsa (12):
bpf: Move update_prog_stats to syscall object
bpf: Move bpf_prog_start_time to linux/filter.h
bpf: Count stats for kprobe_multi programs
bpf: Add missed value to kprobe_multi link info
bpf: Add missed value to kprobe perf link info
bpf: Count missed stats in trace_call_bpf
bpf: Move bpf_prog_run_array down in the header file
bpf: Count run stats in bpf_prog_run_array
bpftool: Display missed count for kprobe_multi link
bpftool: Display missed count for kprobe perf link selftests/bpf: Add test missed counts of perf event link kprobe elftests/bpf: Add test recursion stats of perf event link kprobe

 include/linux/bpf.h                                         | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------------------------
 include/linux/trace_events.h                                |   6 ++++--
 include/uapi/linux/bpf.h                                    |   2 ++
 kernel/bpf/syscall.c                                        |  36 +++++++++++++++++++++++++------
 kernel/bpf/trampoline.c                                     |  45 +++++----------------------------------
 kernel/trace/bpf_trace.c                                    |  17 ++++++++++++---
 kernel/trace/trace_kprobe.c                                 |   5 ++++-
 tools/bpf/bpftool/link.c                                    |   8 ++++++-
 tools/include/uapi/linux/bpf.h                              |   2 ++
 tools/testing/selftests/bpf/DENYLIST.aarch64                |   1 +
 tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c       |   5 +++++
 tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h |   2 ++
 tools/testing/selftests/bpf/prog_tests/missed.c             |  97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/missed_kprobe.c           |  30 ++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c |  48 +++++++++++++++++++++++++++++++++++++++++
 15 files changed, 327 insertions(+), 83 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/missed.c
 create mode 100644 tools/testing/selftests/bpf/progs/missed_kprobe.c
 create mode 100644 tools/testing/selftests/bpf/progs/missed_kprobe_recursion.c

.