Re: [PATCH v8 2/2] ARM: kprobes: enable OPTPROBES for ARM 32
On 2014/11/18 14:32, Wang Nan wrote:
> This patch introduce kprobeopt for ARM 32.
>
> Limitations:
> - Currently only kernel compiled with ARM ISA is supported.
>
> - Offset between probe point and optinsn slot must not larger than
>32MiB. Masami Hiramatsu suggests replacing 2 words, it will make
>things complex. Futher patch can make such optimization.
>
> Kprobe opt on ARM is relatively simpler than kprobe opt on x86 because
> ARM instruction is always 4 bytes aligned and 4 bytes long. This patch
> replace probed instruction by a 'b', branch to trampoline code and then
> calls optimized_callback(). optimized_callback() calls opt_pre_handler()
> to execute kprobe handler. It also emulate/simulate replaced instruction.
>
> When unregistering kprobe, the deferred manner of unoptimizer may leave
> branch instruction before optimizer is called. Different from x86_64,
> which only copy the probed insn after optprobe_template_end and
> reexecute them, this patch call singlestep to emulate/simulate the insn
> directly. Futher patch can optimize this behavior.
>
> v1 -> v2:
>
> - Improvement: if replaced instruction is conditional, generate a
>conditional branch instruction for it;
>
> - Introduces RELATIVEJUMP_OPCODES due to ARM kprobe_opcode_t is 4
>bytes;
>
> - Removes size field in struct arch_optimized_insn;
>
> - Use arm_gen_branch() to generate branch instruction;
>
> - Remove all recover logic: ARM doesn't use tail buffer, no need
>recover replaced instructions like x86;
>
> - Remove incorrect CONFIG_THUMB checking;
>
> - can_optimize() always returns true if address is well aligned;
>
> - Improve optimized_callback: using opt_pre_handler();
>
> - Bugfix: correct range checking code and improve comments;
>
> - Fix commit message.
>
> v2 -> v3:
>
> - Rename RELATIVEJUMP_OPCODES to MAX_COPIED_INSNS;
>
> - Remove unneeded checking:
> arch_check_optimized_kprobe(), can_optimize();
>
> - Add missing flush_icache_range() in arch_prepare_optimized_kprobe();
>
> - Remove unneeded 'return;'.
>
> v3 -> v4:
>
> - Use __mem_to_opcode_arm() to translate copied_insn to ensure it
>works in big endian kernel;
>
> - Replace 'nop' placeholder in trampoline code template with
>'.long 0' to avoid confusion: reader may regard 'nop' as an
>instruction, but it is value in fact.
>
> v4 -> v5:
>
> - Don't optimize stack store operations.
>
> - Introduce prepared field to arch_optimized_insn to indicate whether
>it is prepared. Similar to size field with x86. See v1 -> v2.
>
> v5 -> v6:
>
> - Dynamically reserve stack according to instruction.
>
> - Rename: kprobes-opt.c -> kprobes-opt-arm.c.
>
> - Set op->optinsn.insn after all works are done.
>
> v6 -> v7:
>
> - Using checker to check stack consumption.
>
> v7 -> v8:
>
> - Small code adjustments.
>
> Signed-off-by: Wang Nan
> Acked-by: Masami Hiramatsu
> Cc: Jon Medhurst (Tixy)
> Cc: Russell King - ARM Linux
> Cc: Will Deacon
> ---
> arch/arm/Kconfig | 1 +
> arch/arm/include/asm/kprobes.h| 26
> arch/arm/kernel/Makefile | 3 +-
> arch/arm/kernel/kprobes-opt-arm.c | 285
> ++
> 4 files changed, 314 insertions(+), 1 deletion(-)
> create mode 100644 arch/arm/kernel/kprobes-opt-arm.c
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 89c4b5c..8281cea 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -59,6 +59,7 @@ config ARM
> select HAVE_MEMBLOCK
> select HAVE_MOD_ARCH_SPECIFIC if ARM_UNWIND
> select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
> + select HAVE_OPTPROBES if (!THUMB2_KERNEL)
> select HAVE_PERF_EVENTS
> select HAVE_PERF_REGS
> select HAVE_PERF_USER_STACK_DUMP
> diff --git a/arch/arm/include/asm/kprobes.h b/arch/arm/include/asm/kprobes.h
> index 56f9ac6..c1016cb 100644
> --- a/arch/arm/include/asm/kprobes.h
> +++ b/arch/arm/include/asm/kprobes.h
> @@ -50,5 +50,31 @@ int kprobe_fault_handler(struct pt_regs *regs, unsigned
> int fsr);
> int kprobe_exceptions_notify(struct notifier_block *self,
>unsigned long val, void *data);
>
> +/* optinsn template addresses */
> +extern __visible kprobe_opcode_t optprobe_template_entry;
> +extern __visible kprobe_opcode_t optprobe_template_val;
> +extern __visible kprobe_opcode_t optprobe_template_call;
> +extern __visible kprobe_opcode_t optprobe_template_end;
> +
> +#define MAX_OPTIMIZED_LENGTH (4)
> +#define MAX_OPTINSN_SIZE \
> + (((unsigned long)_template_end - \
> + (unsigned long)_template_entry))
> +#define RELATIVEJUMP_SIZE(4)
> +
> +struct arch_optimized_insn {
> + /*
> + * copy of the original instructions.
> + * Different from x86, ARM kprobe_opcode_t is u32.
> + */
> +#define MAX_COPIED_INSN ((RELATIVEJUMP_SIZE) / sizeof(kprobe_opcode_t))
> + kprobe_opcode_t
Re: [PATCH v8 2/2] ARM: kprobes: enable OPTPROBES for ARM 32
On 2014/11/18 14:32, Wang Nan wrote:
This patch introduce kprobeopt for ARM 32.
Limitations:
- Currently only kernel compiled with ARM ISA is supported.
- Offset between probe point and optinsn slot must not larger than
32MiB. Masami Hiramatsu suggests replacing 2 words, it will make
things complex. Futher patch can make such optimization.
Kprobe opt on ARM is relatively simpler than kprobe opt on x86 because
ARM instruction is always 4 bytes aligned and 4 bytes long. This patch
replace probed instruction by a 'b', branch to trampoline code and then
calls optimized_callback(). optimized_callback() calls opt_pre_handler()
to execute kprobe handler. It also emulate/simulate replaced instruction.
When unregistering kprobe, the deferred manner of unoptimizer may leave
branch instruction before optimizer is called. Different from x86_64,
which only copy the probed insn after optprobe_template_end and
reexecute them, this patch call singlestep to emulate/simulate the insn
directly. Futher patch can optimize this behavior.
v1 - v2:
- Improvement: if replaced instruction is conditional, generate a
conditional branch instruction for it;
- Introduces RELATIVEJUMP_OPCODES due to ARM kprobe_opcode_t is 4
bytes;
- Removes size field in struct arch_optimized_insn;
- Use arm_gen_branch() to generate branch instruction;
- Remove all recover logic: ARM doesn't use tail buffer, no need
recover replaced instructions like x86;
- Remove incorrect CONFIG_THUMB checking;
- can_optimize() always returns true if address is well aligned;
- Improve optimized_callback: using opt_pre_handler();
- Bugfix: correct range checking code and improve comments;
- Fix commit message.
v2 - v3:
- Rename RELATIVEJUMP_OPCODES to MAX_COPIED_INSNS;
- Remove unneeded checking:
arch_check_optimized_kprobe(), can_optimize();
- Add missing flush_icache_range() in arch_prepare_optimized_kprobe();
- Remove unneeded 'return;'.
v3 - v4:
- Use __mem_to_opcode_arm() to translate copied_insn to ensure it
works in big endian kernel;
- Replace 'nop' placeholder in trampoline code template with
'.long 0' to avoid confusion: reader may regard 'nop' as an
instruction, but it is value in fact.
v4 - v5:
- Don't optimize stack store operations.
- Introduce prepared field to arch_optimized_insn to indicate whether
it is prepared. Similar to size field with x86. See v1 - v2.
v5 - v6:
- Dynamically reserve stack according to instruction.
- Rename: kprobes-opt.c - kprobes-opt-arm.c.
- Set op-optinsn.insn after all works are done.
v6 - v7:
- Using checker to check stack consumption.
v7 - v8:
- Small code adjustments.
Signed-off-by: Wang Nan wangn...@huawei.com
Acked-by: Masami Hiramatsu masami.hiramatsu...@hitachi.com
Cc: Jon Medhurst (Tixy) t...@linaro.org
Cc: Russell King - ARM Linux li...@arm.linux.org.uk
Cc: Will Deacon will.dea...@arm.com
---
arch/arm/Kconfig | 1 +
arch/arm/include/asm/kprobes.h| 26
arch/arm/kernel/Makefile | 3 +-
arch/arm/kernel/kprobes-opt-arm.c | 285
++
4 files changed, 314 insertions(+), 1 deletion(-)
create mode 100644 arch/arm/kernel/kprobes-opt-arm.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 89c4b5c..8281cea 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -59,6 +59,7 @@ config ARM
select HAVE_MEMBLOCK
select HAVE_MOD_ARCH_SPECIFIC if ARM_UNWIND
select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
+ select HAVE_OPTPROBES if (!THUMB2_KERNEL)
select HAVE_PERF_EVENTS
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
diff --git a/arch/arm/include/asm/kprobes.h b/arch/arm/include/asm/kprobes.h
index 56f9ac6..c1016cb 100644
--- a/arch/arm/include/asm/kprobes.h
+++ b/arch/arm/include/asm/kprobes.h
@@ -50,5 +50,31 @@ int kprobe_fault_handler(struct pt_regs *regs, unsigned
int fsr);
int kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data);
+/* optinsn template addresses */
+extern __visible kprobe_opcode_t optprobe_template_entry;
+extern __visible kprobe_opcode_t optprobe_template_val;
+extern __visible kprobe_opcode_t optprobe_template_call;
+extern __visible kprobe_opcode_t optprobe_template_end;
+
+#define MAX_OPTIMIZED_LENGTH (4)
+#define MAX_OPTINSN_SIZE \
+ (((unsigned long)optprobe_template_end - \
+ (unsigned long)optprobe_template_entry))
+#define RELATIVEJUMP_SIZE(4)
+
+struct arch_optimized_insn {
+ /*
+ * copy of the original instructions.
+ * Different from x86, ARM kprobe_opcode_t is u32.
+ */
+#define MAX_COPIED_INSN ((RELATIVEJUMP_SIZE) / sizeof(kprobe_opcode_t))
+ kprobe_opcode_t copied_insn[MAX_COPIED_INSN];
+ /* detour code
[PATCH v8 2/2] ARM: kprobes: enable OPTPROBES for ARM 32
This patch introduce kprobeopt for ARM 32.
Limitations:
- Currently only kernel compiled with ARM ISA is supported.
- Offset between probe point and optinsn slot must not larger than
32MiB. Masami Hiramatsu suggests replacing 2 words, it will make
things complex. Futher patch can make such optimization.
Kprobe opt on ARM is relatively simpler than kprobe opt on x86 because
ARM instruction is always 4 bytes aligned and 4 bytes long. This patch
replace probed instruction by a 'b', branch to trampoline code and then
calls optimized_callback(). optimized_callback() calls opt_pre_handler()
to execute kprobe handler. It also emulate/simulate replaced instruction.
When unregistering kprobe, the deferred manner of unoptimizer may leave
branch instruction before optimizer is called. Different from x86_64,
which only copy the probed insn after optprobe_template_end and
reexecute them, this patch call singlestep to emulate/simulate the insn
directly. Futher patch can optimize this behavior.
v1 -> v2:
- Improvement: if replaced instruction is conditional, generate a
conditional branch instruction for it;
- Introduces RELATIVEJUMP_OPCODES due to ARM kprobe_opcode_t is 4
bytes;
- Removes size field in struct arch_optimized_insn;
- Use arm_gen_branch() to generate branch instruction;
- Remove all recover logic: ARM doesn't use tail buffer, no need
recover replaced instructions like x86;
- Remove incorrect CONFIG_THUMB checking;
- can_optimize() always returns true if address is well aligned;
- Improve optimized_callback: using opt_pre_handler();
- Bugfix: correct range checking code and improve comments;
- Fix commit message.
v2 -> v3:
- Rename RELATIVEJUMP_OPCODES to MAX_COPIED_INSNS;
- Remove unneeded checking:
arch_check_optimized_kprobe(), can_optimize();
- Add missing flush_icache_range() in arch_prepare_optimized_kprobe();
- Remove unneeded 'return;'.
v3 -> v4:
- Use __mem_to_opcode_arm() to translate copied_insn to ensure it
works in big endian kernel;
- Replace 'nop' placeholder in trampoline code template with
'.long 0' to avoid confusion: reader may regard 'nop' as an
instruction, but it is value in fact.
v4 -> v5:
- Don't optimize stack store operations.
- Introduce prepared field to arch_optimized_insn to indicate whether
it is prepared. Similar to size field with x86. See v1 -> v2.
v5 -> v6:
- Dynamically reserve stack according to instruction.
- Rename: kprobes-opt.c -> kprobes-opt-arm.c.
- Set op->optinsn.insn after all works are done.
v6 -> v7:
- Using checker to check stack consumption.
v7 -> v8:
- Small code adjustments.
Signed-off-by: Wang Nan
Acked-by: Masami Hiramatsu
Cc: Jon Medhurst (Tixy)
Cc: Russell King - ARM Linux
Cc: Will Deacon
---
arch/arm/Kconfig | 1 +
arch/arm/include/asm/kprobes.h| 26
arch/arm/kernel/Makefile | 3 +-
arch/arm/kernel/kprobes-opt-arm.c | 285 ++
4 files changed, 314 insertions(+), 1 deletion(-)
create mode 100644 arch/arm/kernel/kprobes-opt-arm.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 89c4b5c..8281cea 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -59,6 +59,7 @@ config ARM
select HAVE_MEMBLOCK
select HAVE_MOD_ARCH_SPECIFIC if ARM_UNWIND
select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
+ select HAVE_OPTPROBES if (!THUMB2_KERNEL)
select HAVE_PERF_EVENTS
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
diff --git a/arch/arm/include/asm/kprobes.h b/arch/arm/include/asm/kprobes.h
index 56f9ac6..c1016cb 100644
--- a/arch/arm/include/asm/kprobes.h
+++ b/arch/arm/include/asm/kprobes.h
@@ -50,5 +50,31 @@ int kprobe_fault_handler(struct pt_regs *regs, unsigned int
fsr);
int kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data);
+/* optinsn template addresses */
+extern __visible kprobe_opcode_t optprobe_template_entry;
+extern __visible kprobe_opcode_t optprobe_template_val;
+extern __visible kprobe_opcode_t optprobe_template_call;
+extern __visible kprobe_opcode_t optprobe_template_end;
+
+#define MAX_OPTIMIZED_LENGTH (4)
+#define MAX_OPTINSN_SIZE \
+ (((unsigned long)_template_end - \
+ (unsigned long)_template_entry))
+#define RELATIVEJUMP_SIZE (4)
+
+struct arch_optimized_insn {
+ /*
+* copy of the original instructions.
+* Different from x86, ARM kprobe_opcode_t is u32.
+*/
+#define MAX_COPIED_INSN((RELATIVEJUMP_SIZE) / sizeof(kprobe_opcode_t))
+ kprobe_opcode_t copied_insn[MAX_COPIED_INSN];
+ /* detour code buffer */
+ kprobe_opcode_t *insn;
+ /*
+* we always copies one instruction on arm32,
+* size always be 4, so no size field.
+*/
+};
#endif /* _ARM_KPROBES_H */
diff --git a/arch/arm/kernel/Makefile
[PATCH v8 2/2] ARM: kprobes: enable OPTPROBES for ARM 32
This patch introduce kprobeopt for ARM 32.
Limitations:
- Currently only kernel compiled with ARM ISA is supported.
- Offset between probe point and optinsn slot must not larger than
32MiB. Masami Hiramatsu suggests replacing 2 words, it will make
things complex. Futher patch can make such optimization.
Kprobe opt on ARM is relatively simpler than kprobe opt on x86 because
ARM instruction is always 4 bytes aligned and 4 bytes long. This patch
replace probed instruction by a 'b', branch to trampoline code and then
calls optimized_callback(). optimized_callback() calls opt_pre_handler()
to execute kprobe handler. It also emulate/simulate replaced instruction.
When unregistering kprobe, the deferred manner of unoptimizer may leave
branch instruction before optimizer is called. Different from x86_64,
which only copy the probed insn after optprobe_template_end and
reexecute them, this patch call singlestep to emulate/simulate the insn
directly. Futher patch can optimize this behavior.
v1 - v2:
- Improvement: if replaced instruction is conditional, generate a
conditional branch instruction for it;
- Introduces RELATIVEJUMP_OPCODES due to ARM kprobe_opcode_t is 4
bytes;
- Removes size field in struct arch_optimized_insn;
- Use arm_gen_branch() to generate branch instruction;
- Remove all recover logic: ARM doesn't use tail buffer, no need
recover replaced instructions like x86;
- Remove incorrect CONFIG_THUMB checking;
- can_optimize() always returns true if address is well aligned;
- Improve optimized_callback: using opt_pre_handler();
- Bugfix: correct range checking code and improve comments;
- Fix commit message.
v2 - v3:
- Rename RELATIVEJUMP_OPCODES to MAX_COPIED_INSNS;
- Remove unneeded checking:
arch_check_optimized_kprobe(), can_optimize();
- Add missing flush_icache_range() in arch_prepare_optimized_kprobe();
- Remove unneeded 'return;'.
v3 - v4:
- Use __mem_to_opcode_arm() to translate copied_insn to ensure it
works in big endian kernel;
- Replace 'nop' placeholder in trampoline code template with
'.long 0' to avoid confusion: reader may regard 'nop' as an
instruction, but it is value in fact.
v4 - v5:
- Don't optimize stack store operations.
- Introduce prepared field to arch_optimized_insn to indicate whether
it is prepared. Similar to size field with x86. See v1 - v2.
v5 - v6:
- Dynamically reserve stack according to instruction.
- Rename: kprobes-opt.c - kprobes-opt-arm.c.
- Set op-optinsn.insn after all works are done.
v6 - v7:
- Using checker to check stack consumption.
v7 - v8:
- Small code adjustments.
Signed-off-by: Wang Nan wangn...@huawei.com
Acked-by: Masami Hiramatsu masami.hiramatsu...@hitachi.com
Cc: Jon Medhurst (Tixy) t...@linaro.org
Cc: Russell King - ARM Linux li...@arm.linux.org.uk
Cc: Will Deacon will.dea...@arm.com
---
arch/arm/Kconfig | 1 +
arch/arm/include/asm/kprobes.h| 26
arch/arm/kernel/Makefile | 3 +-
arch/arm/kernel/kprobes-opt-arm.c | 285 ++
4 files changed, 314 insertions(+), 1 deletion(-)
create mode 100644 arch/arm/kernel/kprobes-opt-arm.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 89c4b5c..8281cea 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -59,6 +59,7 @@ config ARM
select HAVE_MEMBLOCK
select HAVE_MOD_ARCH_SPECIFIC if ARM_UNWIND
select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
+ select HAVE_OPTPROBES if (!THUMB2_KERNEL)
select HAVE_PERF_EVENTS
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
diff --git a/arch/arm/include/asm/kprobes.h b/arch/arm/include/asm/kprobes.h
index 56f9ac6..c1016cb 100644
--- a/arch/arm/include/asm/kprobes.h
+++ b/arch/arm/include/asm/kprobes.h
@@ -50,5 +50,31 @@ int kprobe_fault_handler(struct pt_regs *regs, unsigned int
fsr);
int kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data);
+/* optinsn template addresses */
+extern __visible kprobe_opcode_t optprobe_template_entry;
+extern __visible kprobe_opcode_t optprobe_template_val;
+extern __visible kprobe_opcode_t optprobe_template_call;
+extern __visible kprobe_opcode_t optprobe_template_end;
+
+#define MAX_OPTIMIZED_LENGTH (4)
+#define MAX_OPTINSN_SIZE \
+ (((unsigned long)optprobe_template_end - \
+ (unsigned long)optprobe_template_entry))
+#define RELATIVEJUMP_SIZE (4)
+
+struct arch_optimized_insn {
+ /*
+* copy of the original instructions.
+* Different from x86, ARM kprobe_opcode_t is u32.
+*/
+#define MAX_COPIED_INSN((RELATIVEJUMP_SIZE) / sizeof(kprobe_opcode_t))
+ kprobe_opcode_t copied_insn[MAX_COPIED_INSN];
+ /* detour code buffer */
+ kprobe_opcode_t *insn;
+ /*
+* we always copies one instruction on arm32,
+* size always be 4, so
