mips static function tracer support

From: Wu Zhangjin <[email protected]>

if -pg of gcc is enabled. a calling to _mcount will be inserted to each kernel function. so, there is a possibility to trace the functions in _mcount.

here is the implementation of mips specific _mcount for static function tracer.

-ffunction-sections option not works with -pg, so disable it if enables FUNCTION_TRACER.

Signed-off-by Wu Zhangjin <[email protected]>

---
 arch/mips/Kconfig              |    2 +
 arch/mips/Makefile             |    2 +
 arch/mips/include/asm/ftrace.h |   25 ++++++++++-
 arch/mips/kernel/Makefile      |    8 +++
 arch/mips/kernel/mcount.S      |   98 ++++++++++++++++++++++++++++++++++++++++
 arch/mips/kernel/mips_ksyms.c  |    5 ++
 6 files changed, 139 insertions(+), 1 deletions(-)
 create mode 100644 arch/mips/kernel/mcount.S

arch/mips/Kconfig +2 -0

index 09b1287..d5c01ca 100644
@@ -4,6 +4,8 @@ config MIPS
 	select HAVE_IDE
 	select HAVE_OPROFILE
 	select HAVE_ARCH_KGDB
+	select HAVE_FUNCTION_TRACER
+	select HAVE_FUNCTION_TRACE_MCOUNT_TEST
 	# Horrible source of confusion.  Die, die, die ...
 	select EMBEDDED
 	select RTC_LIB

arch/mips/Makefile +2 -0

index c4cae9e..f86fb15 100644
@@ -48,7 +48,9 @@ ifneq ($(SUBARCH),$(ARCH))
   endif
 endif
 
+ifndef CONFIG_FUNCTION_TRACER
 cflags-y := -ffunction-sections
+endif
 cflags-y += $(call cc-option, -mno-check-zero-division)
 
 ifdef CONFIG_32BIT

arch/mips/include/asm/ftrace.h +24 -1

index 40a8c17..5f8ebcf 100644
@@ -1 +1,24 @@
-/* empty */
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive for
+ * more details.
+ *
+ * Copyright (C) 2009 DSLab, Lanzhou University, China
+ * Author: Wu Zhangjin <[email protected]>
+ */
+
+#ifndef _ASM_MIPS_FTRACE_H
+#define _ASM_MIPS_FTRACE_H
+
+#ifdef CONFIG_FUNCTION_TRACER
+
+#define MCOUNT_ADDR ((unsigned long)(_mcount))
+#define MCOUNT_INSN_SIZE 4		/* sizeof mcount call */
+
+#ifndef __ASSEMBLY__
+extern void _mcount(void);
+#define mcount _mcount
+
+#endif /* __ASSEMBLY__ */
+#endif /* CONFIG_FUNCTION_TRACER */
+#endif /* _ASM_MIPS_FTRACE_H */

arch/mips/kernel/Makefile +0 -0

index e961221..d167dde 100644

arch/mips/kernel/Makefile +5 -0

+CFLAGS_REMOVE_early_printk.o = -pg
+endif
+
 obj-$(CONFIG_CEVT_BCM1480)	+= cevt-bcm1480.o
 obj-$(CONFIG_CEVT_R4K_LIB)	+= cevt-r4k.o
 obj-$(CONFIG_MIPS_MT_SMTC)	+= cevt-smtc.o

@@ -24,6 +30,8 @@ obj-$(CONFIG_SYNC_R4K)		+= sync-r4k.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 obj-$(CONFIG_MODULES)		+= mips_ksyms.o module.o
 
+obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o
+
 obj-$(CONFIG_CPU_LOONGSON2)	+= r4k_fpu.o r4k_switch.o
 obj-$(CONFIG_CPU_MIPS32)	+= r4k_fpu.o r4k_switch.o
 obj-$(CONFIG_CPU_MIPS64)	+= r4k_fpu.o r4k_switch.o

arch/mips/kernel/mcount.S new file +0 -1

new file mode 100644
index 0000000..268724e
--- /dev/null

Quoted 88 lines · On Fri, 29 May 2009, [email protected] wrote:

From: Wu Zhangjin <[email protected]>

if -pg of gcc is enabled. a calling to _mcount will be inserted to each kernel function. so, there is a possibility to trace the functions in _mcount.

here is the implementation of mips specific _mcount for static function tracer.

-ffunction-sections option not works with -pg, so disable it if enables FUNCTION_TRACER.

Signed-off-by Wu Zhangjin <[email protected]>

---
 arch/mips/Kconfig              |    2 +
 arch/mips/Makefile             |    2 +
 arch/mips/include/asm/ftrace.h |   25 ++++++++++-
 arch/mips/kernel/Makefile      |    8 +++
 arch/mips/kernel/mcount.S      |   98 ++++++++++++++++++++++++++++++++++++++++
 arch/mips/kernel/mips_ksyms.c  |    5 ++
 6 files changed, 139 insertions(+), 1 deletions(-)
 create mode 100644 arch/mips/kernel/mcount.S

arch/mips/Kconfig +2 -0

index 09b1287..d5c01ca 100644
@@ -4,6 +4,8 @@ config MIPS
 	select HAVE_IDE
 	select HAVE_OPROFILE
 	select HAVE_ARCH_KGDB
+	select HAVE_FUNCTION_TRACER
+	select HAVE_FUNCTION_TRACE_MCOUNT_TEST
 	# Horrible source of confusion.  Die, die, die ...
 	select EMBEDDED
 	select RTC_LIB

arch/mips/Makefile +2 -0

index c4cae9e..f86fb15 100644
@@ -48,7 +48,9 @@ ifneq ($(SUBARCH),$(ARCH))
   endif
 endif
 
+ifndef CONFIG_FUNCTION_TRACER
 cflags-y := -ffunction-sections
+endif
 cflags-y += $(call cc-option, -mno-check-zero-division)
 
 ifdef CONFIG_32BIT

arch/mips/include/asm/ftrace.h +24 -1

index 40a8c17..5f8ebcf 100644
@@ -1 +1,24 @@
-/* empty */
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive for
+ * more details.
+ *
+ * Copyright (C) 2009 DSLab, Lanzhou University, China
+ * Author: Wu Zhangjin <[email protected]>
+ */
+
+#ifndef _ASM_MIPS_FTRACE_H
+#define _ASM_MIPS_FTRACE_H
+
+#ifdef CONFIG_FUNCTION_TRACER
+
+#define MCOUNT_ADDR ((unsigned long)(_mcount))
+#define MCOUNT_INSN_SIZE 4		/* sizeof mcount call */
+
+#ifndef __ASSEMBLY__
+extern void _mcount(void);
+#define mcount _mcount
+
+#endif /* __ASSEMBLY__ */
+#endif /* CONFIG_FUNCTION_TRACER */
+#endif /* _ASM_MIPS_FTRACE_H */

arch/mips/kernel/Makefile +0 -0

index e961221..d167dde 100644
@@ -8,6 +8,12 @@ obj-y		+= cpu-probe.o branch.o entry.o genex.o irq.o process.o \
 		   ptrace.o reset.o setup.o signal.o syscall.o \
 		   time.o topology.o traps.o unaligned.o watch.o
 

arch/mips/kernel/Makefile obj-y += cpu-probe.o branch.o entry.o genex.o irq.o process.o \ · line 13

Quoted 3 lines

arch/mips/kernel/Makefile +3 -0

+ifdef CONFIG_FUNCTION_TRACER
+# Do not profile debug and lowlevel utilities
+CFLAGS_REMOVE_mcount.o = -pg

mcount.S is an assembly file, the above is for C files. So it is not needed.

-- Steve

Quoted 19 lines

arch/mips/kernel/Makefile +5 -0

+CFLAGS_REMOVE_early_printk.o = -pg
+endif
+
 obj-$(CONFIG_CEVT_BCM1480)	+= cevt-bcm1480.o
 obj-$(CONFIG_CEVT_R4K_LIB)	+= cevt-r4k.o
 obj-$(CONFIG_MIPS_MT_SMTC)	+= cevt-smtc.o

@@ -24,6 +30,8 @@ obj-$(CONFIG_SYNC_R4K)		+= sync-r4k.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 obj-$(CONFIG_MODULES)		+= mips_ksyms.o module.o
 
+obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o
+
 obj-$(CONFIG_CPU_LOONGSON2)	+= r4k_fpu.o r4k_switch.o
 obj-$(CONFIG_CPU_MIPS32)	+= r4k_fpu.o r4k_switch.o
 obj-$(CONFIG_CPU_MIPS64)	+= r4k_fpu.o r4k_switch.o

arch/mips/kernel/mcount.S new file +0 -1

new file mode 100644
index 0000000..268724e
--- /dev/null

From: Wu Zhangjin <[email protected]>

dynamic function tracer need to replace "nop" to "jumps & links" and something reversely.

Signed-off-by Wu Zhangjin <[email protected]>

---
 arch/mips/Kconfig              |    3 +
 arch/mips/include/asm/ftrace.h |   10 ++
 arch/mips/kernel/Makefile      |    2 +
 arch/mips/kernel/ftrace.c      |  217 ++++++++++++++++++++++++++++++++++++++++
 arch/mips/kernel/mcount.S      |   31 ++++++
 scripts/Makefile.build         |    1 +
 scripts/recordmcount.pl        |   32 +++++-
 7 files changed, 290 insertions(+), 6 deletions(-)
 create mode 100644 arch/mips/kernel/ftrace.c

arch/mips/Kconfig +3 -0

index d5c01ca..0c00536 100644
@@ -6,6 +6,9 @@ config MIPS
 	select HAVE_ARCH_KGDB
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUNCTION_TRACE_MCOUNT_TEST
+	select HAVE_DYNAMIC_FTRACE
+	select HAVE_FTRACE_MCOUNT_RECORD
+	select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE
 	# Horrible source of confusion.  Die, die, die ...
 	select EMBEDDED
 	select RTC_LIB

arch/mips/include/asm/ftrace.h +10 -0

index 5f8ebcf..b4970c9 100644
@@ -19,6 +19,16 @@
 extern void _mcount(void);
 #define mcount _mcount
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+/* reloction of mcount call site is the same as the address */
+static inline unsigned long ftrace_call_adjust(unsigned long addr)
+{
+	return addr;
+}
+
+struct dyn_arch_ftrace {
+};
+#endif /*  CONFIG_DYNAMIC_FTRACE */
 #endif /* __ASSEMBLY__ */
 #endif /* CONFIG_FUNCTION_TRACER */
 #endif /* _ASM_MIPS_FTRACE_H */

arch/mips/kernel/Makefile +2 -0

index d167dde..6b1a8a5 100644
@@ -11,6 +11,7 @@ obj-y		+= cpu-probe.o branch.o entry.o genex.o irq.o process.o \
 ifdef CONFIG_FUNCTION_TRACER
 # Do not profile debug and lowlevel utilities
 CFLAGS_REMOVE_mcount.o = -pg
+CFLAGS_REMOVE_ftrace.o = -pg
 CFLAGS_REMOVE_early_printk.o = -pg
 endif
 

@@ -31,6 +32,7 @@ obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 obj-$(CONFIG_MODULES)		+= mips_ksyms.o module.o
 
 obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o
+obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o
 
 obj-$(CONFIG_CPU_LOONGSON2)	+= r4k_fpu.o r4k_switch.o
 obj-$(CONFIG_CPU_MIPS32)	+= r4k_fpu.o r4k_switch.o

arch/mips/kernel/ftrace.c new file +128 -0

new file mode 100644
index 0000000..827c128
@@ -0,0 +1,217 @@
+/*
+ * Code for replacing ftrace calls with jumps.
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <[email protected]>
+ * Copyright (C) 2009 DSLab, Lanzhou University, China
+ * Author: Wu Zhangjin <[email protected]>
+ *
+ * Thanks goes to Steven Rostedt for writing the original x86 version.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/hardirq.h>
+#include <linux/uaccess.h>
+#include <linux/percpu.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/ftrace.h>
+
+#include <asm/cacheflush.h>
+#include <asm/ftrace.h>
+#include <asm/asm.h>
+#include <asm/unistd.h>
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+#define JAL 0x0c000000	/* jump & link: ip --> ra, jump to target */
+#define ADDR_MASK 0x03ffffff	/*  op_code|addr : 31...26|25 ....0 */
+
+static unsigned int ftrace_nop = 0x00000000;
+
+static unsigned char *ftrace_call_replace(unsigned long op_code,
+					  unsigned long addr)
+{
+    static unsigned int op;
+
+    op = op_code | ((addr >> 2) & ADDR_MASK);
+
+    return (unsigned char *) &op;
+}
+
+static atomic_t nmi_running = ATOMIC_INIT(0);
+static int mod_code_status;	/* holds return value of text write */
+static int mod_code_write;	/* set when NMI should do the write */
+static void *mod_code_ip;	/* holds the IP to write to */
+static void *mod_code_newcode;	/* holds the text to write to the IP */
+
+static unsigned nmi_wait_count;
+static atomic_t nmi_update_count = ATOMIC_INIT(0);
+
+int ftrace_arch_read_dyn_info(char *buf, int size)
+{
+    int r;
+
+    r = snprintf(buf, size, "%u %u",
+		 nmi_wait_count, atomic_read(&nmi_update_count));
+    return r;
+}
+
+static void ftrace_mod_code(void)
+{
+    /*
+     * Yes, more than one CPU process can be writing to mod_code_status.
+     *    (and the code itself)
+     * But if one were to fail, then they all should, and if one were
+     * to succeed, then they all should.
+     */
+    mod_code_status = probe_kernel_write(mod_code_ip, mod_code_newcode,
+					 MCOUNT_INSN_SIZE);
+
+    /* if we fail, then kill any new writers */
+    if (mod_code_status)
+		mod_code_write = 0;
+}
+
+void ftrace_nmi_enter(void)
+{
+    atomic_inc(&nmi_running);
+    /* Must have nmi_running seen before reading write flag */
+    smp_mb();
+    if (mod_code_write) {
+		ftrace_mod_code();
+		atomic_inc(&nmi_update_count);
+    }
+}
+
+void ftrace_nmi_exit(void)
+{
+    /* Finish all executions before clearing nmi_running */
+    smp_wmb();
+    atomic_dec(&nmi_running);
+}
+
+static void wait_for_nmi(void)
+{
+    int waited = 0;
+
+    while (atomic_read(&nmi_running)) {
+		waited = 1;
+		cpu_relax();
+    }
+
+    if (waited)
+		nmi_wait_count++;
+}
+
+static int do_ftrace_mod_code(unsigned long ip, void *new_code)
+{
+    mod_code_ip = (void *) ip;
+    mod_code_newcode = new_code;
+
+    /* The buffers need to be visible before we let NMIs write them */
+    smp_wmb();
+
+    mod_code_write = 1;
+
+    /* Make sure write bit is visible before we wait on NMIs */
+    smp_mb();
+
+    wait_for_nmi();
+
+    /* Make sure all running NMIs have finished before we write the code */
+    smp_mb();
+
+    ftrace_mod_code();
+
+    /* Make sure the write happens before clearing the bit */
+    smp_wmb();

arch/mips/kernel/ftrace.c new file +7 -0

+
+static unsigned char *ftrace_nop_replace(void)
+{
+    return (unsigned char *) &ftrace_nop;
+}
+
+static int

arch/mips/kernel/ftrace.c new file +48 -0

+     *
+     * No real locking needed, this code is run through
+     * kstop_machine, or before SMP starts.
+     */
+
+    /* read the text we want to modify */
+    if (probe_kernel_read(replaced, (void *) ip, MCOUNT_INSN_SIZE))
+		return -EFAULT;
+
+    /* Make sure it is what we expect it to be */
+    if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
+		return -EINVAL;
+
+    /* replace the text with the new text */
+    if (do_ftrace_mod_code(ip, new_code))
+		return -EPERM;
+
+    return 0;
+}
+
+int ftrace_make_nop(struct module *mod,
+		    struct dyn_ftrace *rec, unsigned long addr)
+{
+    unsigned char *new, *old;
+
+    old = ftrace_call_replace(JAL, addr);
+    new = ftrace_nop_replace();
+
+    return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+    unsigned char *new, *old;
+
+    old = ftrace_nop_replace();
+    new = ftrace_call_replace(JAL, addr);
+
+    return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+    unsigned long ip = (unsigned long) (&ftrace_call);
+    unsigned char old[MCOUNT_INSN_SIZE], *new;
+    int ret;
+
+    memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);

arch/mips/kernel/ftrace.c new file +4 -0

+
+    return 0;
+}
+#endif				/* CONFIG_DYNAMIC_FTRACE */

arch/mips/kernel/mcount.S +31 -0

index 268724e..ce8a0ba 100644
@@ -67,6 +67,35 @@
 	move ra, $1
 	.endm
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+LEAF(_mcount)
+	RESTORE_SP_FOR_32BIT
+ 	RETURN_BACK
+ 	END(_mcount)
+
+NESTED(ftrace_caller, PT_SIZE, ra)
+	RESTORE_SP_FOR_32BIT
+	lw	t0, function_trace_stop
+	bnez	t0, ftrace_stub
+	nop
+
+	MCOUNT_SAVE_REGS
+
+	MCOUNT_SET_ARGS
+	.globl ftrace_call
+ftrace_call:
+	jal	ftrace_stub
+	nop
+
+	MCOUNT_RESTORE_REGS
+	.globl ftrace_stub
+ftrace_stub:
+	RETURN_BACK
+	END(ftrace_caller)
+
+#else	/* ! CONFIG_DYNAMIC_FTRACE */
+
 NESTED(_mcount, PT_SIZE, ra)
 	RESTORE_SP_FOR_32BIT
 	PTR_L	t0, function_trace_stop

@@ -94,5 +123,7 @@ ftrace_stub:
 	RETURN_BACK
 	END(_mcount)
 
+#endif	/* ! CONFIG_DYNAMIC_FTRACE */
+
 	.set at
 	.set reorder

scripts/Makefile.build +0 -0

index 5c4b7a4..548d575 100644

scripts/recordmcount.pl +12 -3

index 409596e..e963948 100755
@@ -100,13 +100,13 @@ $P =~ s@.*/@@g;
 
 my $V = '0.1';
 
-if ($#ARGV < 7) {
-	print "usage: $P arch bits objdump objcopy cc ld nm rm mv is_module inputfile\n";
+if ($#ARGV < 8) {
+	print "usage: $P arch endian bits objdump objcopy cc ld nm rm mv is_module inputfile\n";
 	print "version: $V\n";
 	exit(1);
 }
 
-my ($arch, $bits, $objdump, $objcopy, $cc,
+my ($arch, $endian, $bits, $objdump, $objcopy, $cc,
     $ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV;
 
 # This file refers to mcount and shouldn't be ftraced, so lets' ignore it

@@ -213,6 +213,26 @@ if ($arch eq "x86_64") {
     if ($is_module eq "0") {
         $cc .= " -mconstant-gp";
     }
+
+} elsif ($arch eq "mips") {
+	$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
+	$objdump .= " -Melf-trad".$endian."mips ";
+
+	if ($endian eq "big") {
+		$endian = " -EB ";
+		$ld .= " -melf".$bits."btsmip";
+	} else {

scripts/recordmcount.pl +2 -2

     #
     # Step 6: Link the global version to our list.
     #
-    `$ld -r $globalobj $mcount_o -o $globalmix`;
+    `$ld -r $globalobj $mcount_o -o $globalmix 2>&1 >/dev/null`;
 
     #
     # Step 7: Convert the local functions back into local symbols

@@ -454,7 +474,7 @@ if ($#converts >= 0) {
     `$objcopy $locallist $globalmix $inputfile`;
 
     # Remove the temp files
-    `$rm $globalobj $globalmix`;
+    `$rm $globalobj $globalmix 2>&1 >/dev/null`;
 
 } else {
 

Signature · 1 line

1.6.0.4

Quoted 215 lines · On Fri, 29 May 2009, [email protected] wrote:

From: Wu Zhangjin <[email protected]>

dynamic function tracer need to replace "nop" to "jumps & links" and something reversely.

Signed-off-by Wu Zhangjin <[email protected]>

---
 arch/mips/Kconfig              |    3 +
 arch/mips/include/asm/ftrace.h |   10 ++
 arch/mips/kernel/Makefile      |    2 +
 arch/mips/kernel/ftrace.c      |  217 ++++++++++++++++++++++++++++++++++++++++
 arch/mips/kernel/mcount.S      |   31 ++++++
 scripts/Makefile.build         |    1 +
 scripts/recordmcount.pl        |   32 +++++-
 7 files changed, 290 insertions(+), 6 deletions(-)
 create mode 100644 arch/mips/kernel/ftrace.c

arch/mips/Kconfig +3 -0

index d5c01ca..0c00536 100644
@@ -6,6 +6,9 @@ config MIPS
 	select HAVE_ARCH_KGDB
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUNCTION_TRACE_MCOUNT_TEST
+	select HAVE_DYNAMIC_FTRACE
+	select HAVE_FTRACE_MCOUNT_RECORD
+	select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE
 	# Horrible source of confusion.  Die, die, die ...
 	select EMBEDDED
 	select RTC_LIB

arch/mips/include/asm/ftrace.h +10 -0

index 5f8ebcf..b4970c9 100644
@@ -19,6 +19,16 @@
 extern void _mcount(void);
 #define mcount _mcount
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+/* reloction of mcount call site is the same as the address */
+static inline unsigned long ftrace_call_adjust(unsigned long addr)
+{
+	return addr;
+}
+
+struct dyn_arch_ftrace {
+};
+#endif /*  CONFIG_DYNAMIC_FTRACE */
 #endif /* __ASSEMBLY__ */
 #endif /* CONFIG_FUNCTION_TRACER */
 #endif /* _ASM_MIPS_FTRACE_H */

arch/mips/kernel/Makefile +2 -0

index d167dde..6b1a8a5 100644
@@ -11,6 +11,7 @@ obj-y		+= cpu-probe.o branch.o entry.o genex.o irq.o process.o \
 ifdef CONFIG_FUNCTION_TRACER
 # Do not profile debug and lowlevel utilities
 CFLAGS_REMOVE_mcount.o = -pg
+CFLAGS_REMOVE_ftrace.o = -pg
 CFLAGS_REMOVE_early_printk.o = -pg
 endif
 

@@ -31,6 +32,7 @@ obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 obj-$(CONFIG_MODULES)		+= mips_ksyms.o module.o
 
 obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o
+obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o
 
 obj-$(CONFIG_CPU_LOONGSON2)	+= r4k_fpu.o r4k_switch.o
 obj-$(CONFIG_CPU_MIPS32)	+= r4k_fpu.o r4k_switch.o

arch/mips/kernel/ftrace.c new file +137 -0

new file mode 100644
index 0000000..827c128
@@ -0,0 +1,217 @@
+/*
+ * Code for replacing ftrace calls with jumps.
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <[email protected]>
+ * Copyright (C) 2009 DSLab, Lanzhou University, China
+ * Author: Wu Zhangjin <[email protected]>
+ *
+ * Thanks goes to Steven Rostedt for writing the original x86 version.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/hardirq.h>
+#include <linux/uaccess.h>
+#include <linux/percpu.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/ftrace.h>
+
+#include <asm/cacheflush.h>
+#include <asm/ftrace.h>
+#include <asm/asm.h>
+#include <asm/unistd.h>
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+#define JAL 0x0c000000	/* jump & link: ip --> ra, jump to target */
+#define ADDR_MASK 0x03ffffff	/*  op_code|addr : 31...26|25 ....0 */
+
+static unsigned int ftrace_nop = 0x00000000;
+
+static unsigned char *ftrace_call_replace(unsigned long op_code,
+					  unsigned long addr)
+{
+    static unsigned int op;
+
+    op = op_code | ((addr >> 2) & ADDR_MASK);
+
+    return (unsigned char *) &op;
+}
+
+static atomic_t nmi_running = ATOMIC_INIT(0);
+static int mod_code_status;	/* holds return value of text write */
+static int mod_code_write;	/* set when NMI should do the write */
+static void *mod_code_ip;	/* holds the IP to write to */
+static void *mod_code_newcode;	/* holds the text to write to the IP */
+
+static unsigned nmi_wait_count;
+static atomic_t nmi_update_count = ATOMIC_INIT(0);
+
+int ftrace_arch_read_dyn_info(char *buf, int size)
+{
+    int r;
+
+    r = snprintf(buf, size, "%u %u",
+		 nmi_wait_count, atomic_read(&nmi_update_count));
+    return r;
+}
+
+static void ftrace_mod_code(void)
+{
+    /*
+     * Yes, more than one CPU process can be writing to mod_code_status.
+     *    (and the code itself)
+     * But if one were to fail, then they all should, and if one were
+     * to succeed, then they all should.
+     */
+    mod_code_status = probe_kernel_write(mod_code_ip, mod_code_newcode,
+					 MCOUNT_INSN_SIZE);
+
+    /* if we fail, then kill any new writers */
+    if (mod_code_status)
+		mod_code_write = 0;
+}
+
+void ftrace_nmi_enter(void)
+{
+    atomic_inc(&nmi_running);
+    /* Must have nmi_running seen before reading write flag */
+    smp_mb();
+    if (mod_code_write) {
+		ftrace_mod_code();
+		atomic_inc(&nmi_update_count);
+    }
+}
+
+void ftrace_nmi_exit(void)
+{
+    /* Finish all executions before clearing nmi_running */
+    smp_wmb();
+    atomic_dec(&nmi_running);
+}
+
+static void wait_for_nmi(void)
+{
+    int waited = 0;
+
+    while (atomic_read(&nmi_running)) {
+		waited = 1;
+		cpu_relax();
+    }
+
+    if (waited)
+		nmi_wait_count++;
+}
+
+static int do_ftrace_mod_code(unsigned long ip, void *new_code)
+{
+    mod_code_ip = (void *) ip;
+    mod_code_newcode = new_code;
+
+    /* The buffers need to be visible before we let NMIs write them */
+    smp_wmb();
+
+    mod_code_write = 1;
+
+    /* Make sure write bit is visible before we wait on NMIs */
+    smp_mb();
+
+    wait_for_nmi();
+
+    /* Make sure all running NMIs have finished before we write the code */
+    smp_mb();
+
+    ftrace_mod_code();
+
+    /* Make sure the write happens before clearing the bit */
+    smp_wmb();
+
+    mod_code_write = 0;
+
+    /* make sure NMIs see the cleared bit */
+    smp_mb();
+
+    wait_for_nmi();
+
+    return mod_code_status;

arch/mips/kernel/ftrace.c line 138

Quoted 1 line

arch/mips/kernel/ftrace.c new file +1 -0

+}

Hmm, this is basically exactly the same as x86's version. I wounder if we should make a helper function in generic code to let archs use it. We can put the do_ftrace_mod_code into kernel/trace/ftrace.c and have weak functions for the ftrace_mod_code. If the arch needs this to handle NMIs, then it can use it. This code was tricky to write, and I would hate to have it duplicated in every arch.

Quoted 12 lines

arch/mips/kernel/ftrace.c new file +12 -0

+
+static unsigned char *ftrace_nop_replace(void)
+{
+    return (unsigned char *) &ftrace_nop;
+}
+
+static int
+ftrace_modify_code(unsigned long ip, unsigned char *old_code,
+		   unsigned char *new_code)
+{
+    unsigned char replaced[MCOUNT_INSN_SIZE];
+

arch/mips/kernel/ftrace.c line 155

Quoted 5 lines

arch/mips/kernel/ftrace.c new file +5 -0

+    /*
+     * Note: Due to modules and __init, code can
+     *  disappear and change, we need to protect against faulting
+     *  as well as code changing. We do this by using the
+     *  probe_kernel_* functions.

hehe, this is an old comment. We don't touch __init sections anymore. I need to remove it from the x86 file.

Quoted 48 lines

arch/mips/kernel/ftrace.c new file +48 -0

+     *
+     * No real locking needed, this code is run through
+     * kstop_machine, or before SMP starts.
+     */
+
+    /* read the text we want to modify */
+    if (probe_kernel_read(replaced, (void *) ip, MCOUNT_INSN_SIZE))
+		return -EFAULT;
+
+    /* Make sure it is what we expect it to be */
+    if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
+		return -EINVAL;
+
+    /* replace the text with the new text */
+    if (do_ftrace_mod_code(ip, new_code))
+		return -EPERM;
+
+    return 0;
+}
+
+int ftrace_make_nop(struct module *mod,
+		    struct dyn_ftrace *rec, unsigned long addr)
+{
+    unsigned char *new, *old;
+
+    old = ftrace_call_replace(JAL, addr);
+    new = ftrace_nop_replace();
+
+    return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+    unsigned char *new, *old;
+
+    old = ftrace_nop_replace();
+    new = ftrace_call_replace(JAL, addr);
+
+    return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+    unsigned long ip = (unsigned long) (&ftrace_call);
+    unsigned char old[MCOUNT_INSN_SIZE], *new;
+    int ret;
+
+    memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);

arch/mips/kernel/ftrace.c line 213

Quoted 10 lines

arch/mips/kernel/ftrace.c new file +10 -0

+    new = ftrace_call_replace(JAL, (unsigned long) func);
+    ret = ftrace_modify_code(ip, old, new);
+
+    return ret;
+}
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+    /* The return code is retured via data */
+    *(unsigned long *) data = 0;

egad, I need to clean that up too. I should return the true error code with ret. That is legacy from the first version of the dynamic ftrace code.

This review is showing all the flaws of my own work ;-)

Quoted 58 lines

arch/mips/kernel/ftrace.c new file +4 -0

+
+    return 0;
+}
+#endif				/* CONFIG_DYNAMIC_FTRACE */

arch/mips/kernel/mcount.S +31 -0

index 268724e..ce8a0ba 100644
@@ -67,6 +67,35 @@
 	move ra, $1
 	.endm
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+LEAF(_mcount)
+	RESTORE_SP_FOR_32BIT
+ 	RETURN_BACK
+ 	END(_mcount)
+
+NESTED(ftrace_caller, PT_SIZE, ra)
+	RESTORE_SP_FOR_32BIT
+	lw	t0, function_trace_stop
+	bnez	t0, ftrace_stub
+	nop
+
+	MCOUNT_SAVE_REGS
+
+	MCOUNT_SET_ARGS
+	.globl ftrace_call
+ftrace_call:
+	jal	ftrace_stub
+	nop
+
+	MCOUNT_RESTORE_REGS
+	.globl ftrace_stub
+ftrace_stub:
+	RETURN_BACK
+	END(ftrace_caller)
+
+#else	/* ! CONFIG_DYNAMIC_FTRACE */
+
 NESTED(_mcount, PT_SIZE, ra)
 	RESTORE_SP_FOR_32BIT
 	PTR_L	t0, function_trace_stop

@@ -94,5 +123,7 @@ ftrace_stub:
 	RETURN_BACK
 	END(_mcount)
 
+#endif	/* ! CONFIG_DYNAMIC_FTRACE */
+
 	.set at
 	.set reorder

scripts/Makefile.build +0 -0

index 5c4b7a4..548d575 100644
@@ -207,6 +207,7 @@ endif
 

scripts/Makefile.build endif · line 213

Quoted 6 lines

scripts/Makefile.build +1 -0

 ifdef CONFIG_FTRACE_MCOUNT_RECORD
 cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
+	"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
 	"$(if $(CONFIG_64BIT),64,32)" \
 	"$(OBJDUMP)" "$(OBJCOPY)" "$(CC)" "$(LD)" "$(NM)" "$(RM)" "$(MV)" \
 	"$(if $(part-of-module),1,0)" "$(@)";

This big/little endian addition, I would like in its own patch.

Quoted 34 lines

scripts/recordmcount.pl +12 -3

index 409596e..e963948 100755
@@ -100,13 +100,13 @@ $P =~ s@.*/@@g;
 
 my $V = '0.1';
 
-if ($#ARGV < 7) {
-	print "usage: $P arch bits objdump objcopy cc ld nm rm mv is_module inputfile\n";
+if ($#ARGV < 8) {
+	print "usage: $P arch endian bits objdump objcopy cc ld nm rm mv is_module inputfile\n";
 	print "version: $V\n";
 	exit(1);
 }
 
-my ($arch, $bits, $objdump, $objcopy, $cc,
+my ($arch, $endian, $bits, $objdump, $objcopy, $cc,
     $ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV;
 
 # This file refers to mcount and shouldn't be ftraced, so lets' ignore it

@@ -213,6 +213,26 @@ if ($arch eq "x86_64") {
     if ($is_module eq "0") {
         $cc .= " -mconstant-gp";
     }
+
+} elsif ($arch eq "mips") {
+	$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
+	$objdump .= " -Melf-trad".$endian."mips ";
+
+	if ($endian eq "big") {
+		$endian = " -EB ";
+		$ld .= " -melf".$bits."btsmip";
+	} else {

scripts/recordmcount.pl if ($arch eq "x86_64") { · line 234

Quoted 10 lines

scripts/recordmcount.pl +10 -0

+		$endian = " -EL ";
+		$ld .= " -melf".$bits."ltsmip";
+	}
+
+	$cc .= " -mno-abicalls -fno-pic -mabi=" . $bits . $endian;
+    $ld .= $endian;
+
+    if ($bits == 64) {
+		$type = ".dword";
+    }

The mips addition to the recordmcount.pl is OK to keep with this patch.

scripts/recordmcount.pl if ($#converts >= 0) { · line 464

Quoted 10 lines

scripts/recordmcount.pl +2 -1

+
 } else {
     die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
 }

@@ -441,12 +461,12 @@ if ($#converts >= 0) {
     #
     # Step 5: set up each local function as a global
     #
-    `$objcopy $globallist $inputfile $globalobj`;
+    `$objcopy $globallist $inputfile $globalobj 2>&1 >/dev/null`;

Are these spitting out errors?

-- Steve

Quoted 22 lines

scripts/recordmcount.pl +2 -2

     #
     # Step 6: Link the global version to our list.
     #
-    `$ld -r $globalobj $mcount_o -o $globalmix`;
+    `$ld -r $globalobj $mcount_o -o $globalmix 2>&1 >/dev/null`;
 
     #
     # Step 7: Convert the local functions back into local symbols

@@ -454,7 +474,7 @@ if ($#converts >= 0) {
     `$objcopy $locallist $globalmix $inputfile`;
 
     # Remove the temp files
-    `$rm $globalobj $globalmix`;
+    `$rm $globalobj $globalmix 2>&1 >/dev/null`;
 
 } else {
 

Signature · 1 line

1.6.0.4

Quoted 10 lines · Steven Rostedt

Quoted 1 line · On Fri, 29 May 2009, [email protected] wrote:

From: Wu Zhangjin <[email protected]>

Hmm, this is basically exactly the same as x86's version. I wounder if we should make a helper function in generic code to let archs use it. We can put the do_ftrace_mod_code into kernel/trace/ftrace.c and have weak functions for the ftrace_mod_code. If the arch needs this to handle NMIs, then it can use it. This code was tricky to write, and I would hate to have it duplicated in every arch.

so, when will you put do_ftrace_mod_code into kernel/trace/ftrace.c? i just checked the powerpc version, seems something different, so, we should handle it carefully and tune the relative arch-dependent parts?

Quoted 13 lines

Quoted 13 lines

arch/mips/kernel/ftrace.c new file +12 -0

+
+static unsigned char *ftrace_nop_replace(void)
+{
+    return (unsigned char *) &ftrace_nop;
+}
+
+static int
+ftrace_modify_code(unsigned long ip, unsigned char *old_code,
+		   unsigned char *new_code)
+{
+    unsigned char replaced[MCOUNT_INSN_SIZE];
+

Quoted 9 lines

arch/mips/kernel/ftrace.c line 155

Quoted 5 lines

arch/mips/kernel/ftrace.c new file +5 -0

+    /*
+     * Note: Due to modules and __init, code can
+     *  disappear and change, we need to protect against faulting
+     *  as well as code changing. We do this by using the
+     *  probe_kernel_* functions.

hehe, this is an old comment. We don't touch __init sections anymore. I need to remove it from the x86 file.

Removed, this is the same in powerpc version.

Quoted 63 lines

Quoted 49 lines

arch/mips/kernel/ftrace.c new file +48 -0

+     *
+     * No real locking needed, this code is run through
+     * kstop_machine, or before SMP starts.
+     */
+
+    /* read the text we want to modify */
+    if (probe_kernel_read(replaced, (void *) ip, MCOUNT_INSN_SIZE))
+		return -EFAULT;
+
+    /* Make sure it is what we expect it to be */
+    if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
+		return -EINVAL;
+
+    /* replace the text with the new text */
+    if (do_ftrace_mod_code(ip, new_code))
+		return -EPERM;
+
+    return 0;
+}
+
+int ftrace_make_nop(struct module *mod,
+		    struct dyn_ftrace *rec, unsigned long addr)
+{
+    unsigned char *new, *old;
+
+    old = ftrace_call_replace(JAL, addr);
+    new = ftrace_nop_replace();
+
+    return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+    unsigned char *new, *old;
+
+    old = ftrace_nop_replace();
+    new = ftrace_call_replace(JAL, addr);
+
+    return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+    unsigned long ip = (unsigned long) (&ftrace_call);
+    unsigned char old[MCOUNT_INSN_SIZE], *new;
+    int ret;
+
+    memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);

arch/mips/kernel/ftrace.c line 213

Quoted 10 lines

arch/mips/kernel/ftrace.c new file +10 -0

+    new = ftrace_call_replace(JAL, (unsigned long) func);
+    ret = ftrace_modify_code(ip, old, new);
+
+    return ret;
+}
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+    /* The return code is retured via data */
+    *(unsigned long *) data = 0;

egad, I need to clean that up too. I should return the true error code with ret. That is legacy from the first version of the dynamic ftrace code.

Quoted 2 lines

This review is showing all the flaws of my own work ;-)

Yeap, most of it is copied from your original x86 version.

there are really lots of duplications among different arch-specific versions, need to cleanup carefully, and should we write something like a helper document for people developing arch-specific version?

Quoted 59 lines

Quoted 59 lines

arch/mips/kernel/ftrace.c new file +4 -0

+
+    return 0;
+}
+#endif				/* CONFIG_DYNAMIC_FTRACE */

arch/mips/kernel/mcount.S +31 -0

index 268724e..ce8a0ba 100644
@@ -67,6 +67,35 @@
 	move ra, $1
 	.endm
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+LEAF(_mcount)
+	RESTORE_SP_FOR_32BIT
+ 	RETURN_BACK
+ 	END(_mcount)
+
+NESTED(ftrace_caller, PT_SIZE, ra)
+	RESTORE_SP_FOR_32BIT
+	lw	t0, function_trace_stop
+	bnez	t0, ftrace_stub
+	nop
+
+	MCOUNT_SAVE_REGS
+
+	MCOUNT_SET_ARGS
+	.globl ftrace_call
+ftrace_call:
+	jal	ftrace_stub
+	nop
+
+	MCOUNT_RESTORE_REGS
+	.globl ftrace_stub
+ftrace_stub:
+	RETURN_BACK
+	END(ftrace_caller)
+
+#else	/* ! CONFIG_DYNAMIC_FTRACE */
+
 NESTED(_mcount, PT_SIZE, ra)
 	RESTORE_SP_FOR_32BIT
 	PTR_L	t0, function_trace_stop

@@ -94,5 +123,7 @@ ftrace_stub:
 	RETURN_BACK
 	END(_mcount)
 
+#endif	/* ! CONFIG_DYNAMIC_FTRACE */
+
 	.set at
 	.set reorder

scripts/Makefile.build +0 -0

index 5c4b7a4..548d575 100644
@@ -207,6 +207,7 @@ endif
 

Quoted 9 lines

scripts/Makefile.build endif · line 213

Quoted 6 lines

scripts/Makefile.build +1 -0

 ifdef CONFIG_FTRACE_MCOUNT_RECORD
 cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
+	"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
 	"$(if $(CONFIG_64BIT),64,32)" \
 	"$(OBJDUMP)" "$(OBJCOPY)" "$(CC)" "$(LD)" "$(NM)" "$(RM)" "$(MV)" \
 	"$(if $(part-of-module),1,0)" "$(@)";

This big/little endian addition, I would like in its own patch.

okay, will split it out later.

Quoted 48 lines

Quoted 35 lines

scripts/recordmcount.pl +12 -3

index 409596e..e963948 100755
@@ -100,13 +100,13 @@ $P =~ s@.*/@@g;
 
 my $V = '0.1';
 
-if ($#ARGV < 7) {
-	print "usage: $P arch bits objdump objcopy cc ld nm rm mv is_module inputfile\n";
+if ($#ARGV < 8) {
+	print "usage: $P arch endian bits objdump objcopy cc ld nm rm mv is_module inputfile\n";
 	print "version: $V\n";
 	exit(1);
 }
 
-my ($arch, $bits, $objdump, $objcopy, $cc,
+my ($arch, $endian, $bits, $objdump, $objcopy, $cc,
     $ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV;
 
 # This file refers to mcount and shouldn't be ftraced, so lets' ignore it

@@ -213,6 +213,26 @@ if ($arch eq "x86_64") {
     if ($is_module eq "0") {
         $cc .= " -mconstant-gp";
     }
+
+} elsif ($arch eq "mips") {
+	$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
+	$objdump .= " -Melf-trad".$endian."mips ";
+
+	if ($endian eq "big") {
+		$endian = " -EB ";
+		$ld .= " -melf".$bits."btsmip";
+	} else {

scripts/recordmcount.pl if ($arch eq "x86_64") { · line 234

Quoted 10 lines

scripts/recordmcount.pl +10 -0

+		$endian = " -EL ";
+		$ld .= " -melf".$bits."ltsmip";
+	}
+
+	$cc .= " -mno-abicalls -fno-pic -mabi=" . $bits . $endian;
+    $ld .= $endian;
+
+    if ($bits == 64) {
+		$type = ".dword";
+    }

The mips addition to the recordmcount.pl is OK to keep with this patch.

Quoted 13 lines

scripts/recordmcount.pl if ($#converts >= 0) { · line 464

Quoted 10 lines

scripts/recordmcount.pl +2 -1

+
 } else {
     die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
 }

@@ -441,12 +461,12 @@ if ($#converts >= 0) {
     #
     # Step 5: set up each local function as a global
     #
-    `$objcopy $globallist $inputfile $globalobj`;
+    `$objcopy $globallist $inputfile $globalobj 2>&1 >/dev/null`;

Are these spitting out errors?

no errors, but some warnings.

seems some files not have _mcount(ooh, I did this patch about two months ago, so not remember the _real_ reason now), so there will some complaint about "No such file ...", this fix just make it not complain again.

arch/mips/kernel/mcount.S +35 -1

index ce8a0ba..bd58f16 100644
@@ -28,6 +28,10 @@
 	PTR_SUBU	sp, PT_SIZE
 	PTR_S	ra, PT_R31(sp)
 	PTR_S	$1, PT_R1(sp)
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	PTR_S	v0, PT_R2(sp)
+	PTR_S	v1, PT_R3(sp)
+#endif
 	PTR_S	a0, PT_R4(sp)
 	PTR_S	a1, PT_R5(sp)
 	PTR_S	a2, PT_R6(sp)

@@ -43,6 +47,10 @@
 	.macro MCOUNT_RESTORE_REGS
 	PTR_L	ra, PT_R31(sp)
 	PTR_L	$1, PT_R1(sp)
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	PTR_L	v0, PT_R2(sp)
+	PTR_L	v1, PT_R3(sp)
+#endif
 	PTR_L	a0, PT_R4(sp)
 	PTR_L	a1, PT_R5(sp)
 	PTR_L	a2, PT_R6(sp)

@@ -89,6 +97,14 @@ ftrace_call:
 	nop
 
 	MCOUNT_RESTORE_REGS
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	.globl ftrace_graph_call
+ftrace_graph_call:
+	j	ftrace_stub
+	nop
+#endif
+
 	.globl ftrace_stub
 ftrace_stub:
 	RETURN_BACK

@@ -106,7 +122,15 @@ NESTED(_mcount, PT_SIZE, ra)
 	PTR_L	t1, ftrace_trace_function /* please don't use t1 later, safe? */
 	bne	t0, t1, static_trace
 	nop
-
+#ifdef	CONFIG_FUNCTION_GRAPH_TRACER
+	PTR_L	t2, ftrace_graph_return
+	bne	t0,	t2, ftrace_graph_caller
+	nop
+	PTR_LA	t0, ftrace_graph_entry_stub
+	PTR_L	t2, ftrace_graph_entry
+	bne	t0,	t2, ftrace_graph_caller
+	nop
+#endif
 	j	ftrace_stub
 	nop
 

@@ -125,5 +149,37 @@ ftrace_stub:
 
 #endif	/* ! CONFIG_DYNAMIC_FTRACE */
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+
+NESTED(ftrace_graph_caller, PT_SIZE, ra)
+	MCOUNT_SAVE_REGS
+
+	MCOUNT_SET_ARGS
+	jal	prepare_ftrace_return
+	nop
+
+	/* overwrite the parent as &return_to_handler: v0 -> $1(at) */

arch/mips/kernel/mcount.S +12 -0

+
+	jal	ftrace_return_to_handler
+	nop
+
+	/* restore the real parent address: v0 -> ra */
+	PTR_S	v0, PT_R31(sp)
+
+	MCOUNT_RESTORE_REGS
+	RETURN_BACK
+
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
 	.set at
 	.set reorder

arch/mips/kernel/vmlinux.lds.S +1 -0

index 58738c8..67435e5 100644
@@ -36,6 +36,7 @@ SECTIONS
 		SCHED_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
+		IRQENTRY_TEXT
 		*(.text.*)
 		*(.fixup)
 		*(.gnu.warning)

Signature · 1 line

1.6.0.4

Quoted 76 lines · On Fri, 29 May 2009, [email protected] wrote:

arch/mips/kernel/mcount.S +39 -1

index ce8a0ba..bd58f16 100644
@@ -28,6 +28,10 @@
 	PTR_SUBU	sp, PT_SIZE
 	PTR_S	ra, PT_R31(sp)
 	PTR_S	$1, PT_R1(sp)
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	PTR_S	v0, PT_R2(sp)
+	PTR_S	v1, PT_R3(sp)
+#endif
 	PTR_S	a0, PT_R4(sp)
 	PTR_S	a1, PT_R5(sp)
 	PTR_S	a2, PT_R6(sp)

@@ -43,6 +47,10 @@
 	.macro MCOUNT_RESTORE_REGS
 	PTR_L	ra, PT_R31(sp)
 	PTR_L	$1, PT_R1(sp)
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	PTR_L	v0, PT_R2(sp)
+	PTR_L	v1, PT_R3(sp)
+#endif
 	PTR_L	a0, PT_R4(sp)
 	PTR_L	a1, PT_R5(sp)
 	PTR_L	a2, PT_R6(sp)

@@ -89,6 +97,14 @@ ftrace_call:
 	nop
 
 	MCOUNT_RESTORE_REGS
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	.globl ftrace_graph_call
+ftrace_graph_call:
+	j	ftrace_stub
+	nop
+#endif
+
 	.globl ftrace_stub
 ftrace_stub:
 	RETURN_BACK

@@ -106,7 +122,15 @@ NESTED(_mcount, PT_SIZE, ra)
 	PTR_L	t1, ftrace_trace_function /* please don't use t1 later, safe? */
 	bne	t0, t1, static_trace
 	nop
-
+#ifdef	CONFIG_FUNCTION_GRAPH_TRACER
+	PTR_L	t2, ftrace_graph_return
+	bne	t0,	t2, ftrace_graph_caller
+	nop
+	PTR_LA	t0, ftrace_graph_entry_stub
+	PTR_L	t2, ftrace_graph_entry
+	bne	t0,	t2, ftrace_graph_caller
+	nop
+#endif
 	j	ftrace_stub
 	nop
 

@@ -125,5 +149,37 @@ ftrace_stub:
 
 #endif	/* ! CONFIG_DYNAMIC_FTRACE */
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+
+NESTED(ftrace_graph_caller, PT_SIZE, ra)
+	MCOUNT_SAVE_REGS
+
+	MCOUNT_SET_ARGS
+	jal	prepare_ftrace_return
+	nop
+
+	/* overwrite the parent as &return_to_handler: v0 -> $1(at) */
+	PTR_S	v0, PT_R1(sp)
+
+	MCOUNT_RESTORE_REGS
+	RETURN_BACK

arch/mips/kernel/mcount.S ftrace_stub: · line 171

Quoted 6 lines

arch/mips/kernel/mcount.S +6 -0

+	END(ftrace_graph_caller)
+
+	.align	2
+	.globl	return_to_handler
+return_to_handler:
+	MCOUNT_SAVE_REGS

I'm not sure which version of function_graph tracer you looked at,

but I'm
pretty sure you can just save the return code registers of the function.

return_to_handler is called on the return of a function.

Thus, any callee
saved registers have already been restored and would also be restored by ftrace_return_to_handler. Any callee registers would have been saved by the function you are about to return to.

Thus the only things you need to save are the return code registers.

-- Steve

Quoted 30 lines

arch/mips/kernel/mcount.S +12 -0

+
+	jal	ftrace_return_to_handler
+	nop
+
+	/* restore the real parent address: v0 -> ra */
+	PTR_S	v0, PT_R31(sp)
+
+	MCOUNT_RESTORE_REGS
+	RETURN_BACK
+
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
 	.set at
 	.set reorder

arch/mips/kernel/vmlinux.lds.S +1 -0

index 58738c8..67435e5 100644
@@ -36,6 +36,7 @@ SECTIONS
 		SCHED_TEXT
 		LOCK_TEXT
 		KPROBES_TEXT
+		IRQENTRY_TEXT
 		*(.text.*)
 		*(.fixup)
 		*(.gnu.warning)

Signature · 1 line

1.6.0.4

Quoted 13 lines

Quoted 13 lines

arch/mips/kernel/mcount.S +13 -0

+
+NESTED(ftrace_graph_caller, PT_SIZE, ra)
+	MCOUNT_SAVE_REGS
+
+	MCOUNT_SET_ARGS
+	jal	prepare_ftrace_return
+	nop
+
+	/* overwrite the parent as &return_to_handler: v0 -> $1(at) */
+	PTR_S	v0, PT_R1(sp)
+
+	MCOUNT_RESTORE_REGS
+	RETURN_BACK

Quoted 8 lines

arch/mips/kernel/mcount.S ftrace_stub: · line 171

Quoted 6 lines

arch/mips/kernel/mcount.S +6 -0

+	END(ftrace_graph_caller)
+
+	.align	2
+	.globl	return_to_handler
+return_to_handler:
+	MCOUNT_SAVE_REGS

I'm not sure which version of function_graph tracer you looked at,

currently, I'm using the master branch of the latest linux-mips git tree. so, the function_graph should be the latest version?

BTW: which git branch should i apply these patches to?

Quoted 5 lines

but I'm
pretty sure you can just save the return code registers of the function.

return_to_handler is called on the return of a function.

Yeap.

Quoted 5 lines

Thus, any callee
saved registers have already been restored and would also be restored by ftrace_return_to_handler. Any callee registers would have been saved by the function you are about to return to.

Quoted 1 line

Thus the only things you need to save are the return code registers.

have tried to not save/restore the arguments(a0-7) registers, the kernel will hang:

CPU 0 Unable to handle kernel paging request at virtual address 0000000c, epc == 80101360, ra == 8010b114
Oops[#1]:
Cpu 0

$ 0   : 00000000 8010b114 00000000 00000000
$ 4   : 87830d00 87830d00 8780c380 10002400
$ 8   : 5607ec00 0000000b 00000000 5607ec00
$12   : 5607ec00 9e3779b9 9e3779b9 00000000
$16   : 00000000 10002400 00000000 87884d00
$20   : 000000d0 801857cc 00000000 80483e00
$24   : 00000000 00000000                  
$28   : 87976000 87977cd8 87977cd8 8010b114
Hi    : 0000000b
Lo    : 5607ec00
epc   : 80101360 plat_irq_dispatch+0x70/0x250
    Not tainted
ra    : 8010b114 return_to_handler+0x0/0x4c
Status: 10002402    KERNEL EXL 
Cause : 50808008
BadVA : 0000000c
PrId  : 00019300 (MIPS 24Kc)
Process bash (pid: 533, threadinfo=87976000, task=8796f560,
tls=2aad5100)
Stack : 00000062 0000006f 80455ef8 9e3779b9 00000000 00000020 87977da8
80101f80
        804b0000 804b0000 87977d08 8010b330 00000000 80483e00 00000000
10002401
        00000000 00000000 804b0000 804b3854 00000000 00000004 08042c2b
8010b0a0
        00000000 0000005f 80455fe4 9e3779b9 9e3779b9 00000000 87884d80
00000020
        00000000 87884d00 000000d0 801857cc 00000000 80483e00 00000000
00000000
        ...
Call Trace:
[<80101360>] plat_irq_dispatch+0x70/0x250
[<80101f80>] ret_from_irq+0x0/0x4
[<80183dd4>] ftrace_run_update_code+0x58/0xdc
[<8018410c>] ftrace_startup+0x7c/0x90
[<80185ab8>] register_ftrace_graph+0x40c/0x440
[<801955a0>] graph_trace_init+0x28/0x54
[<80190d00>] tracer_init+0x34/0x50
[<80190f34>] tracing_set_tracer+0x218/0x2c4
[<801910b8>] tracing_set_trace_write+0xd8/0x144

Code: 00000000  0c05cc3c  02002021 <8c43000c> 02002021  0060f809
00402821  0c04cec0  00000000 
Disabling lock debugging due to kernel taint
Kernel panic - not syncing: Fatal exception in interrupt

so, i think there is really a need to use the current MCOUNT_SAVE/RESTORE_REGS, some arguments registers should be saved. and we can share this common macros :-)

From: Wu Zhangjin <[email protected]>

by default, ring_buffer_time_stamp calling sched_clock(jiffies-based) function to get timestamp, in x86, there is a tsc(64bit) based sched_clock, but in mips, the 'tsc'(clock counter) is only 32bit long, which will easily rollover, and there is no precise sched_clock in mips, we need to get one ourselves.

to avoid invading the whole linux-mips, i do not want to implement a tsc-based native_sched_clock like x86 does. because, there is a need to handling rollover of the only 32-bit long 'tsc' of mips, which will need extra overhead. in reality, i have tried to implement one(just like the ring_buffer_time_stamp here does), but make the kernel hangs when booting, i am not sure why it not work.

herein, i just implement a mips-specific ring_buffer_time_stamp in arch/mips/kernel/ftrace.c via adding __attribute__((weak)) before ring_buffer_time_stamp(...) {} in kernel/trace/ring_buffer.c and do something in arch/mips/kernel/ftrace.c like this:

u64  ring_buffer_time_stamp \
       __attribute__((alias("native_ring_buffer_time_stamp")));

and, as the same, there is also a need to implement a mips-specific trace_clock_local based on the above ring_buffer_timep_stamp, this clock function is called in function graph tracer to get calltime & rettime of a function.

and what about the trace_clock and trace_clock_global function, should we also implement a mips-secific one? i am not sure.

Signed-off-by Wu Zhangjin <[email protected]>

---
 arch/mips/kernel/Makefile       |    2 +
 arch/mips/kernel/csrc-r4k.c     |    2 +-
 arch/mips/kernel/ftrace_clock.c |   77 +++++++++++++++++++++++++++++++++++++++
 kernel/trace/ring_buffer.c      |    3 +-
 kernel/trace/trace_clock.c      |    2 +-
 5 files changed, 83 insertions(+), 3 deletions(-)
 create mode 100644 arch/mips/kernel/ftrace_clock.c

arch/mips/kernel/Makefile +2 -0

index 6b1a8a5..5dec76f 100644
@@ -12,6 +12,7 @@ ifdef CONFIG_FUNCTION_TRACER
 # Do not profile debug and lowlevel utilities
 CFLAGS_REMOVE_mcount.o = -pg
 CFLAGS_REMOVE_ftrace.o = -pg
+CFLAGS_REMOVE_ftrace_clock.o = -pg
 CFLAGS_REMOVE_early_printk.o = -pg
 endif
 

@@ -33,6 +34,7 @@ obj-$(CONFIG_MODULES)		+= mips_ksyms.o module.o
 
 obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o
+obj-$(CONFIG_NOP_TRACER)	+= ftrace_clock.o
 
 obj-$(CONFIG_CPU_LOONGSON2)	+= r4k_fpu.o r4k_switch.o
 obj-$(CONFIG_CPU_MIPS32)	+= r4k_fpu.o r4k_switch.o

arch/mips/kernel/csrc-r4k.c +1 -1

index e95a3cd..3da1c7a 100644
@@ -10,7 +10,7 @@
 
 #include <asm/time.h>
 
-static cycle_t c0_hpt_read(struct clocksource *cs)
+static cycle_t notrace c0_hpt_read(struct clocksource *cs)
 {
 	return read_c0_count();
 }

arch/mips/kernel/ftrace_clock.c new file +77 -0

new file mode 100644
index 0000000..2f3b05a
@@ -0,0 +1,77 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive for
+ * more details.
+ *
+ * Copyright (C) 2009 DSLab, Lanzhou University, China
+ * Author: Wu Zhangjin <[email protected]>
+ */
+
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/jiffies.h>
+#include <linux/clocksource.h>
+#include <linux/ring_buffer.h>
+
+/* Up this if you want to test the TIME_EXTENTS and normalization */
+#ifndef DEBUG_SHIFT
+#define DEBUG_SHIFT 0
+#endif
+
+/* mips-specific ring_buffer_time_stamp implementation,
+ * the original one is defined in kernel/trace/ring_buffer.c
+ */
+
+u64 native_ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu)
+{
+	u64 current_cycles;
+	static unsigned long old_jiffies;
+	static u64 time, old_cycles;
+
+	preempt_disable_notrace();
+    /* update timestamp to avoid missing the timer interrupt */
+	if (time_before(jiffies, old_jiffies)) {
+		old_jiffies = jiffies;
+		time = sched_clock();
+		old_cycles = clock->cycle_last;
+	}
+	current_cycles = clock->read(clock);
+
+	time = (time + cyc2ns(clock, (current_cycles - old_cycles)
+				& clock->mask)) << DEBUG_SHIFT;
+
+	old_cycles = current_cycles;
+	preempt_enable_no_resched_notrace();
+
+	return time;
+}
+
+u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu)
+		__attribute__((alias("native_ring_buffer_time_stamp")));
+
+/*
+ * native_trace_clock_local(): the simplest and least coherent tracing clock.
+ *
+ * Useful for tracing that does not cross to other CPUs nor
+ * does it go through idle events.
+ */
+u64 native_trace_clock_local(void)
+{
+	unsigned long flags;
+	u64 clock;
+
+	/*
+	 * sched_clock() is an architecture implemented, fast, scalable,
+	 * lockless clock. It is not guaranteed to be coherent across
+	 * CPUs, nor across CPU idle events.
+	 */
+	raw_local_irq_save(flags);
+	clock = ring_buffer_time_stamp(NULL, raw_smp_processor_id());
+	raw_local_irq_restore(flags);
+
+	return clock;
+}
+
+u64 trace_clock_local(void)
+		__attribute__((alias("native_trace_clock_local")));
+

kernel/trace/ring_buffer.c +0 -0

index 960cbf4..717bd8e 100644

kernel/trace/ring_buffer.c +0 -0

 	u64 time;
 

kernel/trace/trace_clock.c +1 -1

index b588fd8..78c98c8 100644
@@ -26,7 +26,7 @@
  * Useful for tracing that does not cross to other CPUs nor
  * does it go through idle events.
  */
-u64 notrace trace_clock_local(void)
+u64 __attribute__((weak)) notrace trace_clock_local(void)
 {
 	unsigned long flags;
 	u64 clock;

Signature · 1 line

1.6.0.4

From: Wu Zhangjin <[email protected]>

FIXME: there are several different sys_call_entry in mips64, but currently, i only use the the one in arch/mips/kernel/scall64-o32.S so,if people not use o32 standard, it will not compiled normally.

the system call tracing demo in a debian system on qemu-system-mipsel/malta:

debian-mips-malta:~# mount -t debugfs nodev /debug
debian-mips-malta:~# echo 20000 > /debug/tracing/buffer_size_kb
debian-mips-malta:~# cat /debug/tracing/available_tracers
syscall nop
debian-mips-malta:~# echo syscall > /debug/tracing/current_tracer
debian-mips-malta:~# echo 1 > /debug/tracing/tracing_enabled
debian-mips-malta:~# sleep 1
debian-mips-malta:~# echo 0 > /debug/tracing/tracing_enabled
debian-mips-malta:~# cat /debug/tracing/trace | head -20
           <...>-533   [000]    60.458291: sys_write(fd: 1, buf: 4fc408, count: 8)
           <...>-533   [000]    64.325614: sys_getrlimit(resource: 3, rlim: 530020)
           <...>-533   [000]    64.327089: sys_read(fd: 2, buf: 4fc008, count: 6)
           <...>-533   [000]    64.969663: sys_exit(error_code: 2)
           <...>-533   [000]    65.608794: sys_exit(error_code: 2)
           <...>-533   [000]    66.231796: sys_read(fd: 2, buf: 4fc008, count: 6)
           <...>-533   [000]    66.913687: sys_open(filename: 1, flags: 0, mode: a)
           <...>-533   [000]    66.914617: sys_exit(error_code: 1)
           <...>-533   [000]    70.797507: sys_exit(error_code: 503be8)
           <...>-536   [000]    70.833108: sys_exit(error_code: 2aac6cfc)
           <...>-536   [000]    70.833897: sys_exit(error_code: 2aac6540)
           <...>-536   [000]    70.835711: sys_exit(error_code: 2aac6cfc)
           <...>-536   [000]    70.840609: sys_lchown(filename: 3, user: 7fb08b38, group: 20)
           <...>-533   [000]    71.877785: sys_open(filename: ffffffff, flags: 7fcf08c8, mode: b)
           <...>-533   [000]    75.531122: sys_open(filename: 1, flags: 0, mode: a)

Signed-off-by Wu Zhangjin <[email protected]>

---
 arch/mips/Kconfig                   |    1 +
 arch/mips/include/asm/ptrace.h      |    2 +
 arch/mips/include/asm/reg.h         |    5 ++
 arch/mips/include/asm/syscall.h     |   84 +++++++++++++++++++++++++++++++++++
 arch/mips/include/asm/thread_info.h |    5 ++-
 arch/mips/kernel/Makefile           |    1 +
 arch/mips/kernel/entry.S            |    2 +-
 arch/mips/kernel/ftrace.c           |   71 +++++++++++++++++++++++++++++
 arch/mips/kernel/ptrace.c           |   14 +++++-
 arch/mips/kernel/scall64-o32.S      |    2 +-
 10 files changed, 182 insertions(+), 5 deletions(-)
 create mode 100644 arch/mips/include/asm/syscall.h

arch/mips/Kconfig +1 -0

index ac1437e..f488027 100644
@@ -10,6 +10,7 @@ config MIPS
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE
 	select HAVE_FUNCTION_GRAPH_TRACER
+	select HAVE_FTRACE_SYSCALLS
 	# Horrible source of confusion.  Die, die, die ...
 	select EMBEDDED
 	select RTC_LIB

arch/mips/include/asm/ptrace.h +2 -0

index ce47118..32e5b62 100644
@@ -45,6 +45,8 @@ struct pt_regs {
 	unsigned long cp0_badvaddr;
 	unsigned long cp0_cause;
 	unsigned long cp0_epc;
+	/* Used for restarting system calls */
+	unsigned long orig_v0;
 #ifdef CONFIG_MIPS_MT_SMTC
 	unsigned long cp0_tcstatus;
 #endif /* CONFIG_MIPS_MT_SMTC */

arch/mips/include/asm/reg.h +5 -0

index 634b55d..93d66bc 100644
@@ -65,6 +65,8 @@
 #define EF_CP0_CAUSE		43
 #define EF_UNUSED0		44
 
+#define EF_ORIG_V0		45
+
 #define EF_SIZE			180
 
 #endif

@@ -121,6 +123,9 @@
 #define EF_CP0_STATUS		36
 #define EF_CP0_CAUSE		37
 
+
+#define EF_ORIG_V0			38
+
 #define EF_SIZE			304	/* size in bytes */
 
 #endif /* CONFIG_64BIT */

arch/mips/include/asm/syscall.h new file +84 -0

new file mode 100644
index 0000000..b785098
@@ -0,0 +1,84 @@
+/*
+ * Access to user system call parameters and results
+ *
+ * Copyright (C) 2008 Red Hat, Inc.  All rights reserved.
+ * Copyright (C) 2009 DSLab, Lanzhou University, China
+ * Author: Wu Zhangjin <[email protected]>
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU General Public License v.2.
+ *
+ * See asm-generic/syscall.h for descriptions of what we must do here.
+ */
+
+#ifndef _ASM_SYSCALL_H
+#define _ASM_SYSCALL_H	1
+
+#include <linux/sched.h>
+
+static inline long syscall_get_nr(struct task_struct *task,
+				  struct pt_regs *regs)
+{
+	/*        syscall   Exc-Code: 0 1000 00     v0 */
+	return ((regs->cp0_cause&0xff) == 0x20)  ? regs->regs[2] : -1L;
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+				    struct pt_regs *regs)
+{
+	regs->regs[2] = regs->orig_v0;
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+				     struct pt_regs *regs)
+{
+	return regs->regs[2] ? -regs->regs[2] : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+					    struct pt_regs *regs)
+{
+	return regs->regs[2];
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+					    struct pt_regs *regs,
+					    int error, long val)
+{
+	if (error)
+		regs->regs[2] = -error;
+	else
+		regs->regs[2] = val;
+}
+
+static inline void syscall_get_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 unsigned long *args)
+{
+#ifdef CONFIG_32BIT
+	/* fixme: only 4 argument register available in mip32, so, how to handle
+	 * others?
+	 */
+	BUG_ON(i + n > 4);
+#else
+	BUG_ON(i + n > 6);
+#endif
+	memcpy(args, &regs->regs[4 + i], n * sizeof(args[0]));
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 const unsigned long *args)
+{
+#ifdef CONFIG_32BIT
+	BUG_ON(i + n > 4);
+#else
+	BUG_ON(i + n > 6);
+#endif
+	memcpy(&regs->regs[4 + i], args, n * sizeof(args[0]));
+}
+
+#endif	/* _ASM_SYSCALL_H */

arch/mips/include/asm/thread_info.h +4 -1

index 143a481..1d55dc0 100644
@@ -128,6 +128,7 @@ register struct thread_info *__current_thread_info __asm__("$28");
 #define TIF_32BIT_ADDR		23	/* 32-bit address space (o32/n32) */
 #define TIF_FPUBOUND		24	/* thread bound to FPU-full CPU set */
 #define TIF_LOAD_WATCH		25	/* If set, load watch registers */
+#define TIF_SYSCALL_FTRACE	27	/* for ftrace syscall instrumentation */
 #define TIF_SYSCALL_TRACE	31	/* syscall trace active */
 
 #ifdef CONFIG_MIPS32_O32

@@ -151,11 +152,13 @@ register struct thread_info *__current_thread_info __asm__("$28");
 #define _TIF_32BIT_ADDR		(1<<TIF_32BIT_ADDR)
 #define _TIF_FPUBOUND		(1<<TIF_FPUBOUND)
 #define _TIF_LOAD_WATCH		(1<<TIF_LOAD_WATCH)
+#define _TIF_SYSCALL_FTRACE	(1<<TIF_SYSCALL_FTRACE)
 
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK		(0x0000ffef & ~_TIF_SECCOMP)
 /* work to do on any return to u-space */
-#define _TIF_ALLWORK_MASK	(0x8000ffff & ~_TIF_SECCOMP)
+#define _TIF_ALLWORK_MASK	\
+	((0x8000ffff & ~_TIF_SECCOMP) | _TIF_SYSCALL_FTRACE)
 
 #endif /* __KERNEL__ */
 

arch/mips/kernel/Makefile +1 -0

index 5dec76f..8b4fafa 100644
@@ -34,6 +34,7 @@ obj-$(CONFIG_MODULES)		+= mips_ksyms.o module.o
 
 obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o
+obj-$(CONFIG_FTRACE_SYSCALLS)	+= ftrace.o
 obj-$(CONFIG_NOP_TRACER)	+= ftrace_clock.o
 
 obj-$(CONFIG_CPU_LOONGSON2)	+= r4k_fpu.o r4k_switch.o

arch/mips/kernel/entry.S +1 -1

index ffa3310..786e4ef 100644
@@ -167,7 +167,7 @@ work_notifysig:				# deal with pending signals and
 FEXPORT(syscall_exit_work_partial)
 	SAVE_STATIC
 syscall_exit_work:
-	li	t0, _TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT
+	li	t0, _TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SYSCALL_FTRACE
 	and	t0, a2			# a2 is preloaded with TI_FLAGS
 	beqz	t0, work_pending	# trace bit set?
 	local_irq_enable		# could let do_syscall_trace()

arch/mips/kernel/ftrace.c +71 -0

index e7f15f7..5967998 100644
@@ -22,6 +22,8 @@
 #include <asm/asm.h>
 #include <asm/unistd.h>
 
+#include <trace/syscall.h>
+
 #ifdef CONFIG_DYNAMIC_FTRACE
 
 #define JAL 0x0c000000	/* jump & link: ip --> ra, jump to target */

@@ -287,3 +289,72 @@ out:
     return parent_ip;
 }
 #endif				/* CONFIG_FUNCTION_GRAPH_TRACER */
+
+#ifdef CONFIG_FTRACE_SYSCALLS
+
+extern unsigned long __start_syscalls_metadata[];
+extern unsigned long __stop_syscalls_metadata[];
+
+/* fixme: in mips64, there are different entries of sys_call_table when using
+ * different standards, in loongson2f based machines: Fuloong & Yeeloong, the
+ * system use o32 standard, so here, we only use the sys_call_table in
+ * arch/mips/kernel/scall64-o32.S */
+
+extern unsigned long *sys_call_table;
+
+static struct syscall_metadata **syscalls_metadata;
+
+static struct syscall_metadata *find_syscall_meta(unsigned long *syscall)
+{
+	struct syscall_metadata *start;
+	struct syscall_metadata *stop;
+	char str[KSYM_SYMBOL_LEN];
+
+
+	start = (struct syscall_metadata *)__start_syscalls_metadata;
+	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
+	kallsyms_lookup((unsigned long) syscall, NULL, NULL, NULL, str);
+
+	for ( ; start < stop; start++) {
+		if (start->name && !strcmp(start->name, str))
+			return start;
+	}
+	return NULL;
+}
+
+struct syscall_metadata *syscall_nr_to_meta(int nr)
+{
+	if (!syscalls_metadata || nr >= __NR_Linux_syscalls || nr < 0)
+		return NULL;
+
+	return syscalls_metadata[nr];
+}
+
+void arch_init_ftrace_syscalls(void)
+{
+	int i;
+	struct syscall_metadata *meta;
+	unsigned long **psys_syscall_table = &sys_call_table;
+	static atomic_t refs;
+
+	if (atomic_inc_return(&refs) != 1)
+		goto end;
+
+	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
+					__NR_Linux_syscalls, GFP_KERNEL);
+	if (!syscalls_metadata) {
+		WARN_ON(1);
+		return;
+	}
+
+	for (i = 0; i < __NR_Linux_syscalls; i++) {
+		meta = find_syscall_meta(psys_syscall_table[i]);
+		syscalls_metadata[i] = meta;
+	}
+	return;
+
+	/* Paranoid: avoid overflow */
+end:
+	atomic_dec(&refs);
+}
+#endif	/* CONFIG_FTRACE_SYSCALLS */

arch/mips/kernel/ptrace.c +12 -2

index 054861c..fa762dc 100644
@@ -25,6 +25,7 @@
 #include <linux/security.h>
 #include <linux/audit.h>
 #include <linux/seccomp.h>
+#include <linux/ftrace.h>
 
 #include <asm/byteorder.h>
 #include <asm/cpu.h>

@@ -39,6 +40,7 @@
 #include <asm/bootinfo.h>
 #include <asm/reg.h>
 
+#include <trace/syscall.h>
 /*
  * Called by kernel/ptrace.c when detaching..
  *

@@ -60,7 +62,7 @@ int ptrace_getregs(struct task_struct *child, __s64 __user *data)
 	struct pt_regs *regs;
 	int i;
 
-	if (!access_ok(VERIFY_WRITE, data, 38 * 8))
+	if (!access_ok(VERIFY_WRITE, data, 39 * 8))
 		return -EIO;
 
 	regs = task_pt_regs(child);

@@ -73,6 +75,7 @@ int ptrace_getregs(struct task_struct *child, __s64 __user *data)
 	__put_user((long)regs->cp0_badvaddr, data + EF_CP0_BADVADDR - EF_R0);
 	__put_user((long)regs->cp0_status, data + EF_CP0_STATUS - EF_R0);
 	__put_user((long)regs->cp0_cause, data + EF_CP0_CAUSE - EF_R0);
+	__put_user((long)regs->orig_v0, data + EF_ORIG_V0 - EF_R0);
 
 	return 0;
 }

@@ -87,7 +90,7 @@ int ptrace_setregs(struct task_struct *child, __s64 __user *data)
 	struct pt_regs *regs;
 	int i;
 
-	if (!access_ok(VERIFY_READ, data, 38 * 8))
+	if (!access_ok(VERIFY_READ, data, 39 * 8))
 		return -EIO;
 
 	regs = task_pt_regs(child);

@@ -97,6 +100,7 @@ int ptrace_setregs(struct task_struct *child, __s64 __user *data)
 	__get_user(regs->lo, data + EF_LO - EF_R0);
 	__get_user(regs->hi, data + EF_HI - EF_R0);
 	__get_user(regs->cp0_epc, data + EF_CP0_EPC - EF_R0);
+	__get_user(regs->orig_v0, data + EF_ORIG_V0 - EF_R0);
 
 	/* badvaddr, status, and cause may not be written.  */
 

@@ -575,6 +579,9 @@ asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
 	if (!(current->ptrace & PT_PTRACED))
 		goto out;
 
+	if (unlikely(test_thread_flag(TIF_SYSCALL_FTRACE)))
+		ftrace_syscall_exit(regs);
+
 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
 		goto out;
 

@@ -594,6 +601,9 @@ asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
 	}
 
 out:
+	if (unlikely(test_thread_flag(TIF_SYSCALL_FTRACE)))
+		ftrace_syscall_enter(regs);
+
 	if (unlikely(current->audit_context) && !entryexit)
 		audit_syscall_entry(audit_arch(), regs->regs[0],
 				    regs->regs[4], regs->regs[5],

arch/mips/kernel/scall64-o32.S +1 -1

index a5598b2..dd1f13a 100644
@@ -202,7 +202,7 @@ einval:	li	v0, -ENOSYS
 
 	.align	3
 	.type	sys_call_table,@object
-sys_call_table:
+EXPORT(sys_call_table)
 	PTR	sys32_syscall			/* 4000 */
 	PTR	sys_exit
 	PTR	sys_fork

Signature · 1 line

1.6.0.4