[PATCH] arm: Add KPROBES_ON_FTRACE supported
Add support for kprobes on ftrace call sites to avoid much of the overhead
with regular kprobes. Try it with simple steps:
cd /sys/kernel/debug/tracing/
echo 'p:myprobe sys_clone r0=%r0 r1=%r1 r2=%r2' > kprobe_events
echo 1 > events/kprobes/enable
echo 1 > events/kprobes/myprobe/enable
cat trace
# tracer: nop
#
# entries-in-buffer/entries-written: 2/2 #P:4
#
#_-=> irqs-off/BH-disabled
# / _=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# / delay
# TASK-PID CPU# | TIMESTAMP FUNCTION
# | | | | | |
sh-75 [000] .33.793362: myprobe:
(sys_clone+0xc/0xa0) r0=0x1200011 r1=0x0 r2=0x0
sh-75 [000] .34.817804: myprobe:
(sys_clone+0xc/0xa0) r0=0x1200011 r1=0x0 r2=0x0
cat /sys/kernel/debug/kprobes/list
c03453e8 k sys_clone+0xc[FTRACE]
^^
Signed-off-by: Jinjie Ruan
---
.../debug/kprobes-on-ftrace/arch-support.txt | 2 +-
arch/arm/Kconfig | 1 +
arch/arm/include/asm/ftrace.h | 17 ++
arch/arm/kernel/ftrace.c | 17 --
arch/arm/probes/Makefile | 1 +
arch/arm/probes/ftrace.c | 53 +++
arch/arm/probes/kprobes/core.c| 32 +++
7 files changed, 105 insertions(+), 18 deletions(-)
create mode 100644 arch/arm/probes/ftrace.c
diff --git a/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt
b/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt
index 02febc883588..4ecd7d53e859 100644
--- a/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt
+++ b/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt
@@ -8,7 +8,7 @@
---
| alpha: | TODO |
| arc: | TODO |
-| arm: | TODO |
+| arm: | ok |
| arm64: | TODO |
|csky: | ok |
| hexagon: | TODO |
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index ee5115252aac..ed13b1743f94 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -114,6 +114,7 @@ config ARM
select HAVE_KERNEL_LZO
select HAVE_KERNEL_XZ
select HAVE_KPROBES if !XIP_KERNEL && !CPU_ENDIAN_BE32 && !CPU_V7M
+ select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL && !CPU_ENDIAN_BE32 &&
!CPU_V7M
select HAVE_KRETPROBES if HAVE_KPROBES
select HAVE_MOD_ARCH_SPECIFIC
select HAVE_NMI
diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 5be3ddc96a50..c8e3f808b70c 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -22,6 +22,23 @@ struct dyn_arch_ftrace {
#endif
};
+/*
+ * The compiler emitted profiling hook consists of
+ *
+ * PUSH{LR}
+ * BL __gnu_mcount_nc
+ *
+ * To turn this combined sequence into a NOP, we need to restore the value of
+ * SP before the PUSH. Let's use an ADD rather than a POP into LR, as LR is not
+ * modified anyway, and reloading LR from memory is highly likely to be less
+ * efficient.
+ */
+#ifdef CONFIG_THUMB2_KERNEL
+#defineNOP 0xf10d0d04 /* add.w sp, sp, #4 */
+#else
+#defineNOP 0xe28dd004 /* add sp, sp, #4 */
+#endif
+
static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
/* With Thumb-2, the recorded addresses have the lsb set */
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index a0b6d1e3812f..f0f1bdf27637 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -25,23 +25,6 @@
#include
#include
-/*
- * The compiler emitted profiling hook consists of
- *
- * PUSH{LR}
- * BL __gnu_mcount_nc
- *
- * To turn this combined sequence into a NOP, we need to restore the value of
- * SP before the PUSH. Let's use an ADD rather than a POP into LR, as LR is not
- * modified anyway, and reloading LR from memory is highly likely to be less
- * efficient.
- */
-#ifdef CONFIG_THUMB2_KERNEL
-#defineNOP 0xf10d0d04 /* add.w sp, sp, #4 */
-#else
-#defineNOP 0xe28dd004 /* add sp, sp, #4 */
-#endif
-
#ifdef CONFIG_DYNAMIC_FTRACE
static int __ftrace_modify_code(void *data)
diff --git a/arch/arm/probes/Makefile b/arch/arm/probes/Makefile
index 8b0ea5ace100..b3c355942a21 100644
--- a/arch/arm/probes/Makefile
+++ b/arch/arm/probes/Makefi
[PATCH v2] arm: Add KPROBES_ON_FTRACE supported
Add support for kprobes on ftrace call sites to avoid much of the overhead
with regular kprobes. Try it with simple steps:
cd /sys/kernel/debug/tracing/
echo 'p:myprobe sys_clone r0=%r0 r1=%r1 r2=%r2' > kprobe_events
echo 1 > events/kprobes/enable
echo 1 > events/kprobes/myprobe/enable
cat trace
# tracer: nop
#
# entries-in-buffer/entries-written: 2/2 #P:4
#
#_-=> irqs-off/BH-disabled
# / _=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# / delay
# TASK-PID CPU# | TIMESTAMP FUNCTION
# | | | | | |
sh-75 [000] .33.793362: myprobe:
(sys_clone+0xc/0xa0) r0=0x1200011 r1=0x0 r2=0x0
sh-75 [000] .34.817804: myprobe:
(sys_clone+0xc/0xa0) r0=0x1200011 r1=0x0 r2=0x0
cat /sys/kernel/debug/kprobes/list
c03453e8 k sys_clone+0xc[FTRACE]
^^
Signed-off-by: Jinjie Ruan
Reported-by: kernel test robot
Closes:
https://lore.kernel.org/oe-kbuild-all/202406160646.j89u1ukk-...@intel.com/
---
v2:
- Fix the allmodconfig compile issue by renaming "NOP" to "FTRACE_NOP".
---
.../debug/kprobes-on-ftrace/arch-support.txt | 2 +-
arch/arm/Kconfig | 1 +
arch/arm/include/asm/ftrace.h | 17 ++
arch/arm/kernel/ftrace.c | 19 +--
arch/arm/probes/Makefile | 1 +
arch/arm/probes/ftrace.c | 53 +++
arch/arm/probes/kprobes/core.c| 32 +++
7 files changed, 106 insertions(+), 19 deletions(-)
create mode 100644 arch/arm/probes/ftrace.c
diff --git a/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt
b/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt
index 02febc883588..4ecd7d53e859 100644
--- a/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt
+++ b/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt
@@ -8,7 +8,7 @@
---
| alpha: | TODO |
| arc: | TODO |
-| arm: | TODO |
+| arm: | ok |
| arm64: | TODO |
|csky: | ok |
| hexagon: | TODO |
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 9f09a16338e3..036381c5d42f 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -114,6 +114,7 @@ config ARM
select HAVE_KERNEL_LZO
select HAVE_KERNEL_XZ
select HAVE_KPROBES if !XIP_KERNEL && !CPU_ENDIAN_BE32 && !CPU_V7M
+ select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL && !CPU_ENDIAN_BE32 &&
!CPU_V7M
select HAVE_KRETPROBES if HAVE_KPROBES
select HAVE_MOD_ARCH_SPECIFIC
select HAVE_NMI
diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 5be3ddc96a50..ecf5590f3657 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -22,6 +22,23 @@ struct dyn_arch_ftrace {
#endif
};
+/*
+ * The compiler emitted profiling hook consists of
+ *
+ * PUSH{LR}
+ * BL __gnu_mcount_nc
+ *
+ * To turn this combined sequence into a NOP, we need to restore the value of
+ * SP before the PUSH. Let's use an ADD rather than a POP into LR, as LR is not
+ * modified anyway, and reloading LR from memory is highly likely to be less
+ * efficient.
+ */
+#ifdef CONFIG_THUMB2_KERNEL
+#defineFTRACE_NOP 0xf10d0d04 /* add.w sp, sp, #4 */
+#else
+#defineFTRACE_NOP 0xe28dd004 /* add sp, sp, #4 */
+#endif
+
static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
/* With Thumb-2, the recorded addresses have the lsb set */
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index e61591f33a6c..0bb372f5aa1d 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -25,23 +25,6 @@
#include
#include
-/*
- * The compiler emitted profiling hook consists of
- *
- * PUSH{LR}
- * BL __gnu_mcount_nc
- *
- * To turn this combined sequence into a NOP, we need to restore the value of
- * SP before the PUSH. Let's use an ADD rather than a POP into LR, as LR is not
- * modified anyway, and reloading LR from memory is highly likely to be less
- * efficient.
- */
-#ifdef CONFIG_THUMB2_KERNEL
-#defineNOP 0xf10d0d04 /* add.w sp, sp, #4 */
-#else
-#defineNOP 0xe28dd004 /* add sp, sp, #4 */
-#endif
-
#i
Re: [PATCH v2] arm: Add KPROBES_ON_FTRACE supported
Gentle ping.
On 2024/6/18 11:52, Jinjie Ruan wrote:
> Add support for kprobes on ftrace call sites to avoid much of the overhead
> with regular kprobes. Try it with simple steps:
>
> cd /sys/kernel/debug/tracing/
> echo 'p:myprobe sys_clone r0=%r0 r1=%r1 r2=%r2' > kprobe_events
> echo 1 > events/kprobes/enable
> echo 1 > events/kprobes/myprobe/enable
> cat trace
> # tracer: nop
> #
> # entries-in-buffer/entries-written: 2/2 #P:4
> #
> #_-=> irqs-off/BH-disabled
> # / _=> need-resched
> # | / _---=> hardirq/softirq
> # || / _--=> preempt-depth
> # ||| / _-=> migrate-disable
> # / delay
> # TASK-PID CPU# | TIMESTAMP FUNCTION
> # | | | | | |
> sh-75 [000] .33.793362: myprobe:
> (sys_clone+0xc/0xa0) r0=0x1200011 r1=0x0 r2=0x0
> sh-75 [000] .34.817804: myprobe:
> (sys_clone+0xc/0xa0) r0=0x1200011 r1=0x0 r2=0x0
>
> cat /sys/kernel/debug/kprobes/list
> c03453e8 k sys_clone+0xc[FTRACE]
> ^^
>
> Signed-off-by: Jinjie Ruan
> Reported-by: kernel test robot
> Closes:
> https://lore.kernel.org/oe-kbuild-all/202406160646.j89u1ukk-...@intel.com/
> ---
> v2:
> - Fix the allmodconfig compile issue by renaming "NOP" to "FTRACE_NOP".
> ---
> .../debug/kprobes-on-ftrace/arch-support.txt | 2 +-
> arch/arm/Kconfig | 1 +
> arch/arm/include/asm/ftrace.h | 17 ++
> arch/arm/kernel/ftrace.c | 19 +--
> arch/arm/probes/Makefile | 1 +
> arch/arm/probes/ftrace.c | 53 +++
> arch/arm/probes/kprobes/core.c| 32 +++
> 7 files changed, 106 insertions(+), 19 deletions(-)
> create mode 100644 arch/arm/probes/ftrace.c
>
> diff --git a/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt
> b/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt
> index 02febc883588..4ecd7d53e859 100644
> --- a/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt
> +++ b/Documentation/features/debug/kprobes-on-ftrace/arch-support.txt
> @@ -8,7 +8,7 @@
> ---
> | alpha: | TODO |
> | arc: | TODO |
> -| arm: | TODO |
> +| arm: | ok |
> | arm64: | TODO |
> |csky: | ok |
> | hexagon: | TODO |
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 9f09a16338e3..036381c5d42f 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -114,6 +114,7 @@ config ARM
> select HAVE_KERNEL_LZO
> select HAVE_KERNEL_XZ
> select HAVE_KPROBES if !XIP_KERNEL && !CPU_ENDIAN_BE32 && !CPU_V7M
> + select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL && !CPU_ENDIAN_BE32 &&
> !CPU_V7M
> select HAVE_KRETPROBES if HAVE_KPROBES
> select HAVE_MOD_ARCH_SPECIFIC
> select HAVE_NMI
> diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
> index 5be3ddc96a50..ecf5590f3657 100644
> --- a/arch/arm/include/asm/ftrace.h
> +++ b/arch/arm/include/asm/ftrace.h
> @@ -22,6 +22,23 @@ struct dyn_arch_ftrace {
> #endif
> };
>
> +/*
> + * The compiler emitted profiling hook consists of
> + *
> + * PUSH{LR}
> + * BL __gnu_mcount_nc
> + *
> + * To turn this combined sequence into a NOP, we need to restore the value of
> + * SP before the PUSH. Let's use an ADD rather than a POP into LR, as LR is
> not
> + * modified anyway, and reloading LR from memory is highly likely to be less
> + * efficient.
> + */
> +#ifdef CONFIG_THUMB2_KERNEL
> +#define FTRACE_NOP 0xf10d0d04 /* add.w sp, sp, #4 */
> +#else
> +#define FTRACE_NOP 0xe28dd004 /* add sp, sp, #4 */
> +#endif
> +
> static inline unsigned long ftrace_call_adjust(unsigned long addr)
> {
> /* With Thumb-2, the recorded addresses have the lsb set */
> diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
> index e61591f33a6c..0bb372f5aa1d 100644
> --- a/arch/arm/kernel/ftrace.c
> +++ b/arch/arm/kernel/ftrace.c
> @@ -25,23 +25,6 @@
> #include
> #include
>
> -/*
> - * The compi
