[PATCH] arm: ftrace: Adds support for ftrace operations

[PATCH] arm: ftrace: Adds support for ftrace operations

[Jean-Jacques Hiblot]

Hi all,

This patch adds support for ftrace operations on the ARM architecture.
This support is needed by kgraft and possibly other ftrace-based tools.
My goal is to have kgraft working on ARM and aarch64.

I tested this patch with a toy implementation of kgraft for ARM and basic
usage of function and function_graph tracers
It doesn't show any problem with the ftrace selftests and the tests found
today in branch ftrace/testing-mystuff of linux-trace repository
(git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git)

Jean-Jacques Hiblot (1):
  arm: ftrace: Adds support for ftrace operations

 arch/arm/Kconfig               |  2 ++
 arch/arm/include/asm/ftrace.h  |  3 ++
 arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
 arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
 4 files changed, 106 insertions(+), 1 deletion(-)

-- 
2.1.3

[PATCH] arm: ftrace: Adds support for ftrace operations

[Jean-Jacques Hiblot]

Hi all,

This patch adds support for ftrace operations on the ARM architecture.
This support is needed by kgraft and possibly other ftrace-based tools.
My goal is to have kgraft working on ARM and aarch64.

I tested this patch with a toy implementation of kgraft for ARM and basic
usage of function and function_graph tracers
It doesn't show any problem with the ftrace selftests and the tests found
today in branch ftrace/testing-mystuff of linux-trace repository
(git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git)

Jean-Jacques Hiblot (1):
  arm: ftrace: Adds support for ftrace operations

 arch/arm/Kconfig               |  2 ++
 arch/arm/include/asm/ftrace.h  |  3 ++
 arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
 arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
 4 files changed, 106 insertions(+), 1 deletion(-)

-- 
2.1.3

[PATCH 01/01] arm: ftrace: Adds support for ftrace operations

[Jean-Jacques Hiblot]

Ftrace operations require that DYNAMIC_FTRACE_WITH_REGS is enabled.
This patch introduces a new ftrace handler that store the registers on the
stack before calling the next stage. The registers are also restored from the
stack before going back to the instrumented function.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
---
 arch/arm/Kconfig               |  2 ++
 arch/arm/include/asm/ftrace.h  |  3 ++
 arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
 arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
 4 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 32cbbd5..6f928ee 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -39,6 +39,7 @@ config ARM
 	select HAVE_DMA_ATTRS
 	select HAVE_DMA_CONTIGUOUS if MMU
 	select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL)
+	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
 	select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL)
 	select HAVE_FUNCTION_GRAPH_TRACER if (!THUMB2_KERNEL)
@@ -72,6 +73,7 @@ config ARM
 	select PERF_USE_VMALLOC
 	select RTC_LIB
 	select SYS_SUPPORTS_APM_EMULATION
+	select FRAME_POINTER if DYNAMIC_FTRACE_WITH_REGS && FUNCTION_GRAPH_TRACER
 	# Above selects are sorted alphabetically; please add new ones
 	# according to that.  Thanks.
 	help
diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 39eb16b..d8e9bea 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -10,6 +10,9 @@ extern void mcount(void);
 extern void __gnu_mcount_nc(void);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
+
+#define ARCH_SUPPORTS_FTRACE_OPS 1
+
 struct dyn_arch_ftrace {
 #ifdef CONFIG_OLD_MCOUNT
 	bool	old_mcount;
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index e52fe5a..9594fe2 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -197,7 +197,10 @@ ENDPROC(ret_from_fork)
 
 	mcount_get_lr	r1			@ lr of instrumented func
 	mcount_adjust_addr	r0, lr		@ instrumented function
-
+	ldr r2, =function_trace_op
+	ldr r2, [r2]				@ pointer to the current
+						@ function tracing op
+	mov r3, #0				@ regs is NULL
 	.globl ftrace_call\suffix
 ftrace_call\suffix:
 	bl	ftrace_stub
@@ -211,6 +214,38 @@ ftrace_graph_call\suffix:
 	mcount_exit
 .endm
 
+.macro __ftrace_regs_caller
+
+	add 	ip, sp, #4	@ move in IP the value of SP as it was
+				@ before the push {lr} of the mcount mechanism
+	stmdb	sp!, {ip,lr,pc}
+	stmdb	sp!, {r0-r11,lr}
+	@ stack content  at this point:
+	@ 0  4         44    48   52       56   60   64
+	@ RO | R1 | ... | R11 | LR | SP + 4 | LR | PC | previous LR |
+
+	mov r3, sp				@ struct pt_regs*
+	ldr r2, =function_trace_op
+	ldr r2, [r2]				@ pointer to the current
+						@ function tracing op
+	ldr	r1, [sp, #64]			@ lr of instrumented func
+	mcount_adjust_addr	r0, lr		@ instrumented function
+
+	.globl ftrace_regs_call
+ftrace_regs_call:
+	bl	ftrace_stub
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	.globl ftrace_graph_regs_call
+ftrace_graph_regs_call:
+	mov	r0, r0
+#endif
+	ldr	lr, [sp, #64]		@ get the previous LR value from stack
+	ldmia	sp, {r0-r11, ip, sp}	@ pop the saved registers INCLUDING
+					@ the stack pointer
+	ret	ip
+.endm
+
 .macro __ftrace_graph_caller
 	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -226,6 +261,24 @@ ftrace_graph_call\suffix:
 	mcount_exit
 .endm
 
+
+.macro __ftrace_graph_regs_caller
+
+	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)
+
+	@ called from __ftrace_regs_caller
+	ldr	r1, [sp, #56]		@ instrumented routine (func)
+	mcount_adjust_addr	r1, r1
+
+	mov	r2, fp			@ frame pointer
+	bl	prepare_ftrace_return
+
+	ldr	lr, [fp, #-4]		@ restore LR from the stack
+	ldmia	sp, {r0-r11, ip, sp}	@ pop the saved registers INCLUDING
+					@ the stack pointer
+	ret	ip
+.endm
+
 #ifdef CONFIG_OLD_MCOUNT
 /*
  * mcount
@@ -312,14 +365,27 @@ UNWIND(.fnstart)
 	__ftrace_caller
 UNWIND(.fnend)
 ENDPROC(ftrace_caller)
+
+ENTRY(ftrace_regs_caller)
+UNWIND(.fnstart)
+	__ftrace_regs_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_regs_caller)
 #endif
 
+
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 ENTRY(ftrace_graph_caller)
 UNWIND(.fnstart)
 	__ftrace_graph_caller
 UNWIND(.fnend)
 ENDPROC(ftrace_graph_caller)
+
+ENTRY(ftrace_graph_regs_caller)
+UNWIND(.fnstart)
+	__ftrace_graph_regs_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_graph_regs_caller)
 #endif
 
 .purgem mcount_enter
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index af9a8a9..35c5743 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -130,6 +130,16 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 	}
 #endif
 
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+	if (!ret) {
+		pc = (unsigned long)&ftrace_regs_call;
+		new = ftrace_call_replace(pc, (unsigned long)func);
+
+		ret = ftrace_modify_code(pc, 0, new, false);
+	}
+#endif
+
 	return ret;
 }
 
@@ -139,6 +149,20 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 	unsigned long ip = rec->ip;
 
 	old = ftrace_nop_replace(rec);
+
+	new = ftrace_call_replace(ip, adjust_address(rec, addr));
+
+	return ftrace_modify_code(rec->ip, old, new, true);
+}
+
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+				unsigned long addr)
+{
+	unsigned long new, old;
+	unsigned long ip = rec->ip;
+
+	old = ftrace_call_replace(ip, adjust_address(rec, old_addr));
+
 	new = ftrace_call_replace(ip, adjust_address(rec, addr));
 
 	return ftrace_modify_code(rec->ip, old, new, true);
@@ -211,6 +235,9 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 extern unsigned long ftrace_graph_call;
 extern unsigned long ftrace_graph_call_old;
 extern void ftrace_graph_caller_old(void);
+extern unsigned long ftrace_graph_regs_call;
+extern void ftrace_graph_regs_caller(void);
+
 
 static int __ftrace_modify_caller(unsigned long *callsite,
 				  void (*func) (void), bool enable)
@@ -240,6 +267,13 @@ static int ftrace_modify_graph_caller(bool enable)
 					     enable);
 #endif
 
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+	if (!ret)
+		ret = __ftrace_modify_caller(&ftrace_graph_regs_call,
+				     ftrace_graph_regs_caller,
+				     enable);
+#endif
+
 	return ret;
 }
 
-- 
2.1.3

[PATCH 01/01] arm: ftrace: Adds support for ftrace operations

[Jean-Jacques Hiblot]

Ftrace operations require that DYNAMIC_FTRACE_WITH_REGS is enabled.
This patch introduces a new ftrace handler that store the registers on the
stack before calling the next stage. The registers are also restored from the
stack before going back to the instrumented function.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
---
 arch/arm/Kconfig               |  2 ++
 arch/arm/include/asm/ftrace.h  |  3 ++
 arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
 arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
 4 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 32cbbd5..6f928ee 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -39,6 +39,7 @@ config ARM
 	select HAVE_DMA_ATTRS
 	select HAVE_DMA_CONTIGUOUS if MMU
 	select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL)
+	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
 	select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL)
 	select HAVE_FUNCTION_GRAPH_TRACER if (!THUMB2_KERNEL)
@@ -72,6 +73,7 @@ config ARM
 	select PERF_USE_VMALLOC
 	select RTC_LIB
 	select SYS_SUPPORTS_APM_EMULATION
+	select FRAME_POINTER if DYNAMIC_FTRACE_WITH_REGS && FUNCTION_GRAPH_TRACER
 	# Above selects are sorted alphabetically; please add new ones
 	# according to that.  Thanks.
 	help
diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 39eb16b..d8e9bea 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -10,6 +10,9 @@ extern void mcount(void);
 extern void __gnu_mcount_nc(void);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
+
+#define ARCH_SUPPORTS_FTRACE_OPS 1
+
 struct dyn_arch_ftrace {
 #ifdef CONFIG_OLD_MCOUNT
 	bool	old_mcount;
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index e52fe5a..9594fe2 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -197,7 +197,10 @@ ENDPROC(ret_from_fork)
 
 	mcount_get_lr	r1			@ lr of instrumented func
 	mcount_adjust_addr	r0, lr		@ instrumented function
-
+	ldr r2, =function_trace_op
+	ldr r2, [r2]				@ pointer to the current
+						@ function tracing op
+	mov r3, #0				@ regs is NULL
 	.globl ftrace_call\suffix
 ftrace_call\suffix:
 	bl	ftrace_stub
@@ -211,6 +214,38 @@ ftrace_graph_call\suffix:
 	mcount_exit
 .endm
 
+.macro __ftrace_regs_caller
+
+	add 	ip, sp, #4	@ move in IP the value of SP as it was
+				@ before the push {lr} of the mcount mechanism
+	stmdb	sp!, {ip,lr,pc}
+	stmdb	sp!, {r0-r11,lr}
+	@ stack content  at this point:
+	@ 0  4         44    48   52       56   60   64
+	@ RO | R1 | ... | R11 | LR | SP + 4 | LR | PC | previous LR |
+
+	mov r3, sp				@ struct pt_regs*
+	ldr r2, =function_trace_op
+	ldr r2, [r2]				@ pointer to the current
+						@ function tracing op
+	ldr	r1, [sp, #64]			@ lr of instrumented func
+	mcount_adjust_addr	r0, lr		@ instrumented function
+
+	.globl ftrace_regs_call
+ftrace_regs_call:
+	bl	ftrace_stub
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	.globl ftrace_graph_regs_call
+ftrace_graph_regs_call:
+	mov	r0, r0
+#endif
+	ldr	lr, [sp, #64]		@ get the previous LR value from stack
+	ldmia	sp, {r0-r11, ip, sp}	@ pop the saved registers INCLUDING
+					@ the stack pointer
+	ret	ip
+.endm
+
 .macro __ftrace_graph_caller
 	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -226,6 +261,24 @@ ftrace_graph_call\suffix:
 	mcount_exit
 .endm
 
+
+.macro __ftrace_graph_regs_caller
+
+	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)
+
+	@ called from __ftrace_regs_caller
+	ldr	r1, [sp, #56]		@ instrumented routine (func)
+	mcount_adjust_addr	r1, r1
+
+	mov	r2, fp			@ frame pointer
+	bl	prepare_ftrace_return
+
+	ldr	lr, [fp, #-4]		@ restore LR from the stack
+	ldmia	sp, {r0-r11, ip, sp}	@ pop the saved registers INCLUDING
+					@ the stack pointer
+	ret	ip
+.endm
+
 #ifdef CONFIG_OLD_MCOUNT
 /*
  * mcount
@@ -312,14 +365,27 @@ UNWIND(.fnstart)
 	__ftrace_caller
 UNWIND(.fnend)
 ENDPROC(ftrace_caller)
+
+ENTRY(ftrace_regs_caller)
+UNWIND(.fnstart)
+	__ftrace_regs_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_regs_caller)
 #endif
 
+
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 ENTRY(ftrace_graph_caller)
 UNWIND(.fnstart)
 	__ftrace_graph_caller
 UNWIND(.fnend)
 ENDPROC(ftrace_graph_caller)
+
+ENTRY(ftrace_graph_regs_caller)
+UNWIND(.fnstart)
+	__ftrace_graph_regs_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_graph_regs_caller)
 #endif
 
 .purgem mcount_enter
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index af9a8a9..35c5743 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -130,6 +130,16 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 	}
 #endif
 
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+	if (!ret) {
+		pc = (unsigned long)&ftrace_regs_call;
+		new = ftrace_call_replace(pc, (unsigned long)func);
+
+		ret = ftrace_modify_code(pc, 0, new, false);
+	}
+#endif
+
 	return ret;
 }
 
@@ -139,6 +149,20 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 	unsigned long ip = rec->ip;
 
 	old = ftrace_nop_replace(rec);
+
+	new = ftrace_call_replace(ip, adjust_address(rec, addr));
+
+	return ftrace_modify_code(rec->ip, old, new, true);
+}
+
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+				unsigned long addr)
+{
+	unsigned long new, old;
+	unsigned long ip = rec->ip;
+
+	old = ftrace_call_replace(ip, adjust_address(rec, old_addr));
+
 	new = ftrace_call_replace(ip, adjust_address(rec, addr));
 
 	return ftrace_modify_code(rec->ip, old, new, true);
@@ -211,6 +235,9 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 extern unsigned long ftrace_graph_call;
 extern unsigned long ftrace_graph_call_old;
 extern void ftrace_graph_caller_old(void);
+extern unsigned long ftrace_graph_regs_call;
+extern void ftrace_graph_regs_caller(void);
+
 
 static int __ftrace_modify_caller(unsigned long *callsite,
 				  void (*func) (void), bool enable)
@@ -240,6 +267,13 @@ static int ftrace_modify_graph_caller(bool enable)
 					     enable);
 #endif
 
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+	if (!ret)
+		ret = __ftrace_modify_caller(&ftrace_graph_regs_call,
+				     ftrace_graph_regs_caller,
+				     enable);
+#endif
+
 	return ret;
 }
 
-- 
2.1.3

Re: [PATCH] arm: ftrace: Adds support for ftrace operations

[Steven Rostedt]

On Fri,  7 Nov 2014 15:59:11 +0100
Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:

> Hi all,
> 
> This patch adds support for ftrace operations on the ARM architecture.
> This support is needed by kgraft and possibly other ftrace-based tools.
> My goal is to have kgraft working on ARM and aarch64.

Can you add this to the change log of the patch. As that would be what
goes into git history. Because honestly, I had no idea what you meant
by "ftrace operations". If I don't understand that term, how can you
expect anyone else to?

> 
> I tested this patch with a toy implementation of kgraft for ARM and basic
> usage of function and function_graph tracers
> It doesn't show any problem with the ftrace selftests and the tests found
> today in branch ftrace/testing-mystuff of linux-trace repository
> (git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git)

Those tests are no where near what I have. Does this code work on the
beagle bone white? If so, I can probably run my full suite on it.

-- Steve

> 
> Jean-Jacques Hiblot (1):
>   arm: ftrace: Adds support for ftrace operations
> 
>  arch/arm/Kconfig               |  2 ++
>  arch/arm/include/asm/ftrace.h  |  3 ++
>  arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
>  arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
>  4 files changed, 106 insertions(+), 1 deletion(-)
> 

[PATCH] arm: ftrace: Adds support for ftrace operations

[Steven Rostedt]

On Fri,  7 Nov 2014 15:59:11 +0100
Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:

> Hi all,
> 
> This patch adds support for ftrace operations on the ARM architecture.
> This support is needed by kgraft and possibly other ftrace-based tools.
> My goal is to have kgraft working on ARM and aarch64.

Can you add this to the change log of the patch. As that would be what
goes into git history. Because honestly, I had no idea what you meant
by "ftrace operations". If I don't understand that term, how can you
expect anyone else to?

> 
> I tested this patch with a toy implementation of kgraft for ARM and basic
> usage of function and function_graph tracers
> It doesn't show any problem with the ftrace selftests and the tests found
> today in branch ftrace/testing-mystuff of linux-trace repository
> (git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git)

Those tests are no where near what I have. Does this code work on the
beagle bone white? If so, I can probably run my full suite on it.

-- Steve

> 
> Jean-Jacques Hiblot (1):
>   arm: ftrace: Adds support for ftrace operations
> 
>  arch/arm/Kconfig               |  2 ++
>  arch/arm/include/asm/ftrace.h  |  3 ++
>  arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
>  arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
>  4 files changed, 106 insertions(+), 1 deletion(-)
> 

Re: [PATCH] arm: ftrace: Adds support for ftrace operations

[Jean-Jacques Hiblot]

On 11/07/2014 05:52 PM, Steven Rostedt wrote:
> On Fri,  7 Nov 2014 15:59:11 +0100
> Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:
> 
>> Hi all,
>>
>> This patch adds support for ftrace operations on the ARM architecture.
>> This support is needed by kgraft and possibly other ftrace-based tools.
>> My goal is to have kgraft working on ARM and aarch64.
> 
> Can you add this to the change log of the patch. As that would be what
> goes into git history. Because honestly, I had no idea what you meant
> by "ftrace operations". If I don't understand that term, how can you
> expect anyone else to?
I'll try to come up with a clearer commit log.
> 
>>
>> I tested this patch with a toy implementation of kgraft for ARM and basic
>> usage of function and function_graph tracers
>> It doesn't show any problem with the ftrace selftests and the tests found
>> today in branch ftrace/testing-mystuff of linux-trace repository
>> (git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git)
> 
> Those tests are no where near what I have. Does this code work on the
> beagle bone white? If so, I can probably run my full suite on it.
It should work on any arm processor, It's not platform or SOC dependent
> 
> -- Steve
> 
>>
>> Jean-Jacques Hiblot (1):
>>   arm: ftrace: Adds support for ftrace operations
>>
>>  arch/arm/Kconfig               |  2 ++
>>  arch/arm/include/asm/ftrace.h  |  3 ++
>>  arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
>>  arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
>>  4 files changed, 106 insertions(+), 1 deletion(-)
>>
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

[PATCH] arm: ftrace: Adds support for ftrace operations

[Jean-Jacques Hiblot]

On 11/07/2014 05:52 PM, Steven Rostedt wrote:
> On Fri,  7 Nov 2014 15:59:11 +0100
> Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:
> 
>> Hi all,
>>
>> This patch adds support for ftrace operations on the ARM architecture.
>> This support is needed by kgraft and possibly other ftrace-based tools.
>> My goal is to have kgraft working on ARM and aarch64.
> 
> Can you add this to the change log of the patch. As that would be what
> goes into git history. Because honestly, I had no idea what you meant
> by "ftrace operations". If I don't understand that term, how can you
> expect anyone else to?
I'll try to come up with a clearer commit log.
> 
>>
>> I tested this patch with a toy implementation of kgraft for ARM and basic
>> usage of function and function_graph tracers
>> It doesn't show any problem with the ftrace selftests and the tests found
>> today in branch ftrace/testing-mystuff of linux-trace repository
>> (git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git)
> 
> Those tests are no where near what I have. Does this code work on the
> beagle bone white? If so, I can probably run my full suite on it.
It should work on any arm processor, It's not platform or SOC dependent
> 
> -- Steve
> 
>>
>> Jean-Jacques Hiblot (1):
>>   arm: ftrace: Adds support for ftrace operations
>>
>>  arch/arm/Kconfig               |  2 ++
>>  arch/arm/include/asm/ftrace.h  |  3 ++
>>  arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
>>  arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
>>  4 files changed, 106 insertions(+), 1 deletion(-)
>>
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

[PATCH v2 00/01] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS

[Jean-Jacques Hiblot]

This patch adds support for ftrace operations on the ARM architecture.
This support is needed by kgraft and possibly other ftrace-based tools.
My goal is to have kgraft working on ARM and aarch64.

I tested this patch with a toy implementation of kgraft for ARM and basic
usage of function and function_graph tracers
It doesn't show any problem with the ftrace selftests and the tests found
today in branch ftrace/testing-mystuff of linux-trace repository
(git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git)


change since v1:
 - changed the title and the commit log of the patch to make it more
   understandable

Jean-Jacques Hiblot (1):
  arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS

 arch/arm/Kconfig               |  2 ++
 arch/arm/include/asm/ftrace.h  |  3 ++
 arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
 arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
 4 files changed, 106 insertions(+), 1 deletion(-)

-- 
2.1.3

[PATCH v2 00/01] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS

[Jean-Jacques Hiblot]

This patch adds support for ftrace operations on the ARM architecture.
This support is needed by kgraft and possibly other ftrace-based tools.
My goal is to have kgraft working on ARM and aarch64.

I tested this patch with a toy implementation of kgraft for ARM and basic
usage of function and function_graph tracers
It doesn't show any problem with the ftrace selftests and the tests found
today in branch ftrace/testing-mystuff of linux-trace repository
(git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git)


change since v1:
 - changed the title and the commit log of the patch to make it more
   understandable

Jean-Jacques Hiblot (1):
  arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS

 arch/arm/Kconfig               |  2 ++
 arch/arm/include/asm/ftrace.h  |  3 ++
 arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
 arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
 4 files changed, 106 insertions(+), 1 deletion(-)

-- 
2.1.3

[PATCH v2 01/01] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS

[Jean-Jacques Hiblot]

The DYNAMIC_FTRACE_WITH_REGS configuration makes it possible for a ftrace
operation to specify if registers need to saved/restored by the ftrace handler.
This is needed by kgraft and possibly other ftrace-based tools, and the ARM
architecture is currently lacking this feature. It would also be the first step
to support the "Kprobes-on-ftrace" optimization on ARM.

This patch introduces a new ftrace handler that stores the registers on the
stack before calling the next stage. The registers are restored from the stack
before going back to the instrumented function.

A side-effect of this patch is to activate the support for ftrace_modify_call()
as it defines ARCH_SUPPORTS_FTRACE_OPS for the ARM architecture

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
---
 arch/arm/Kconfig               |  2 ++
 arch/arm/include/asm/ftrace.h  |  3 ++
 arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
 arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
 4 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 32cbbd5..6f928ee 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -39,6 +39,7 @@ config ARM
 	select HAVE_DMA_ATTRS
 	select HAVE_DMA_CONTIGUOUS if MMU
 	select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL)
+	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
 	select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL)
 	select HAVE_FUNCTION_GRAPH_TRACER if (!THUMB2_KERNEL)
@@ -72,6 +73,7 @@ config ARM
 	select PERF_USE_VMALLOC
 	select RTC_LIB
 	select SYS_SUPPORTS_APM_EMULATION
+	select FRAME_POINTER if DYNAMIC_FTRACE_WITH_REGS && FUNCTION_GRAPH_TRACER
 	# Above selects are sorted alphabetically; please add new ones
 	# according to that.  Thanks.
 	help
diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 39eb16b..d8e9bea 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -10,6 +10,9 @@ extern void mcount(void);
 extern void __gnu_mcount_nc(void);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
+
+#define ARCH_SUPPORTS_FTRACE_OPS 1
+
 struct dyn_arch_ftrace {
 #ifdef CONFIG_OLD_MCOUNT
 	bool	old_mcount;
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index e52fe5a..9594fe2 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -197,7 +197,10 @@ ENDPROC(ret_from_fork)
 
 	mcount_get_lr	r1			@ lr of instrumented func
 	mcount_adjust_addr	r0, lr		@ instrumented function
-
+	ldr r2, =function_trace_op
+	ldr r2, [r2]				@ pointer to the current
+						@ function tracing op
+	mov r3, #0				@ regs is NULL
 	.globl ftrace_call\suffix
 ftrace_call\suffix:
 	bl	ftrace_stub
@@ -211,6 +214,38 @@ ftrace_graph_call\suffix:
 	mcount_exit
 .endm
 
+.macro __ftrace_regs_caller
+
+	add 	ip, sp, #4	@ move in IP the value of SP as it was
+				@ before the push {lr} of the mcount mechanism
+	stmdb	sp!, {ip,lr,pc}
+	stmdb	sp!, {r0-r11,lr}
+	@ stack content  at this point:
+	@ 0  4         44    48   52       56   60   64
+	@ RO | R1 | ... | R11 | LR | SP + 4 | LR | PC | previous LR |
+
+	mov r3, sp				@ struct pt_regs*
+	ldr r2, =function_trace_op
+	ldr r2, [r2]				@ pointer to the current
+						@ function tracing op
+	ldr	r1, [sp, #64]			@ lr of instrumented func
+	mcount_adjust_addr	r0, lr		@ instrumented function
+
+	.globl ftrace_regs_call
+ftrace_regs_call:
+	bl	ftrace_stub
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	.globl ftrace_graph_regs_call
+ftrace_graph_regs_call:
+	mov	r0, r0
+#endif
+	ldr	lr, [sp, #64]		@ get the previous LR value from stack
+	ldmia	sp, {r0-r11, ip, sp}	@ pop the saved registers INCLUDING
+					@ the stack pointer
+	ret	ip
+.endm
+
 .macro __ftrace_graph_caller
 	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -226,6 +261,24 @@ ftrace_graph_call\suffix:
 	mcount_exit
 .endm
 
+
+.macro __ftrace_graph_regs_caller
+
+	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)
+
+	@ called from __ftrace_regs_caller
+	ldr	r1, [sp, #56]		@ instrumented routine (func)
+	mcount_adjust_addr	r1, r1
+
+	mov	r2, fp			@ frame pointer
+	bl	prepare_ftrace_return
+
+	ldr	lr, [fp, #-4]		@ restore LR from the stack
+	ldmia	sp, {r0-r11, ip, sp}	@ pop the saved registers INCLUDING
+					@ the stack pointer
+	ret	ip
+.endm
+
 #ifdef CONFIG_OLD_MCOUNT
 /*
  * mcount
@@ -312,14 +365,27 @@ UNWIND(.fnstart)
 	__ftrace_caller
 UNWIND(.fnend)
 ENDPROC(ftrace_caller)
+
+ENTRY(ftrace_regs_caller)
+UNWIND(.fnstart)
+	__ftrace_regs_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_regs_caller)
 #endif
 
+
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 ENTRY(ftrace_graph_caller)
 UNWIND(.fnstart)
 	__ftrace_graph_caller
 UNWIND(.fnend)
 ENDPROC(ftrace_graph_caller)
+
+ENTRY(ftrace_graph_regs_caller)
+UNWIND(.fnstart)
+	__ftrace_graph_regs_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_graph_regs_caller)
 #endif
 
 .purgem mcount_enter
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index af9a8a9..35c5743 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -130,6 +130,16 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 	}
 #endif
 
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+	if (!ret) {
+		pc = (unsigned long)&ftrace_regs_call;
+		new = ftrace_call_replace(pc, (unsigned long)func);
+
+		ret = ftrace_modify_code(pc, 0, new, false);
+	}
+#endif
+
 	return ret;
 }
 
@@ -139,6 +149,20 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 	unsigned long ip = rec->ip;
 
 	old = ftrace_nop_replace(rec);
+
+	new = ftrace_call_replace(ip, adjust_address(rec, addr));
+
+	return ftrace_modify_code(rec->ip, old, new, true);
+}
+
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+				unsigned long addr)
+{
+	unsigned long new, old;
+	unsigned long ip = rec->ip;
+
+	old = ftrace_call_replace(ip, adjust_address(rec, old_addr));
+
 	new = ftrace_call_replace(ip, adjust_address(rec, addr));
 
 	return ftrace_modify_code(rec->ip, old, new, true);
@@ -211,6 +235,9 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 extern unsigned long ftrace_graph_call;
 extern unsigned long ftrace_graph_call_old;
 extern void ftrace_graph_caller_old(void);
+extern unsigned long ftrace_graph_regs_call;
+extern void ftrace_graph_regs_caller(void);
+
 
 static int __ftrace_modify_caller(unsigned long *callsite,
 				  void (*func) (void), bool enable)
@@ -240,6 +267,13 @@ static int ftrace_modify_graph_caller(bool enable)
 					     enable);
 #endif
 
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+	if (!ret)
+		ret = __ftrace_modify_caller(&ftrace_graph_regs_call,
+				     ftrace_graph_regs_caller,
+				     enable);
+#endif
+
 	return ret;
 }
 
-- 
2.1.3

[PATCH v2 01/01] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS

[Jean-Jacques Hiblot]

The DYNAMIC_FTRACE_WITH_REGS configuration makes it possible for a ftrace
operation to specify if registers need to saved/restored by the ftrace handler.
This is needed by kgraft and possibly other ftrace-based tools, and the ARM
architecture is currently lacking this feature. It would also be the first step
to support the "Kprobes-on-ftrace" optimization on ARM.

This patch introduces a new ftrace handler that stores the registers on the
stack before calling the next stage. The registers are restored from the stack
before going back to the instrumented function.

A side-effect of this patch is to activate the support for ftrace_modify_call()
as it defines ARCH_SUPPORTS_FTRACE_OPS for the ARM architecture

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
---
 arch/arm/Kconfig               |  2 ++
 arch/arm/include/asm/ftrace.h  |  3 ++
 arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
 arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
 4 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 32cbbd5..6f928ee 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -39,6 +39,7 @@ config ARM
 	select HAVE_DMA_ATTRS
 	select HAVE_DMA_CONTIGUOUS if MMU
 	select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL)
+	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU
 	select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL)
 	select HAVE_FUNCTION_GRAPH_TRACER if (!THUMB2_KERNEL)
@@ -72,6 +73,7 @@ config ARM
 	select PERF_USE_VMALLOC
 	select RTC_LIB
 	select SYS_SUPPORTS_APM_EMULATION
+	select FRAME_POINTER if DYNAMIC_FTRACE_WITH_REGS && FUNCTION_GRAPH_TRACER
 	# Above selects are sorted alphabetically; please add new ones
 	# according to that.  Thanks.
 	help
diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 39eb16b..d8e9bea 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -10,6 +10,9 @@ extern void mcount(void);
 extern void __gnu_mcount_nc(void);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
+
+#define ARCH_SUPPORTS_FTRACE_OPS 1
+
 struct dyn_arch_ftrace {
 #ifdef CONFIG_OLD_MCOUNT
 	bool	old_mcount;
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index e52fe5a..9594fe2 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -197,7 +197,10 @@ ENDPROC(ret_from_fork)
 
 	mcount_get_lr	r1			@ lr of instrumented func
 	mcount_adjust_addr	r0, lr		@ instrumented function
-
+	ldr r2, =function_trace_op
+	ldr r2, [r2]				@ pointer to the current
+						@ function tracing op
+	mov r3, #0				@ regs is NULL
 	.globl ftrace_call\suffix
 ftrace_call\suffix:
 	bl	ftrace_stub
@@ -211,6 +214,38 @@ ftrace_graph_call\suffix:
 	mcount_exit
 .endm
 
+.macro __ftrace_regs_caller
+
+	add 	ip, sp, #4	@ move in IP the value of SP as it was
+				@ before the push {lr} of the mcount mechanism
+	stmdb	sp!, {ip,lr,pc}
+	stmdb	sp!, {r0-r11,lr}
+	@ stack content  at this point:
+	@ 0  4         44    48   52       56   60   64
+	@ RO | R1 | ... | R11 | LR | SP + 4 | LR | PC | previous LR |
+
+	mov r3, sp				@ struct pt_regs*
+	ldr r2, =function_trace_op
+	ldr r2, [r2]				@ pointer to the current
+						@ function tracing op
+	ldr	r1, [sp, #64]			@ lr of instrumented func
+	mcount_adjust_addr	r0, lr		@ instrumented function
+
+	.globl ftrace_regs_call
+ftrace_regs_call:
+	bl	ftrace_stub
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	.globl ftrace_graph_regs_call
+ftrace_graph_regs_call:
+	mov	r0, r0
+#endif
+	ldr	lr, [sp, #64]		@ get the previous LR value from stack
+	ldmia	sp, {r0-r11, ip, sp}	@ pop the saved registers INCLUDING
+					@ the stack pointer
+	ret	ip
+.endm
+
 .macro __ftrace_graph_caller
 	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -226,6 +261,24 @@ ftrace_graph_call\suffix:
 	mcount_exit
 .endm
 
+
+.macro __ftrace_graph_regs_caller
+
+	sub	r0, fp, #4		@ &lr of instrumented routine (&parent)
+
+	@ called from __ftrace_regs_caller
+	ldr	r1, [sp, #56]		@ instrumented routine (func)
+	mcount_adjust_addr	r1, r1
+
+	mov	r2, fp			@ frame pointer
+	bl	prepare_ftrace_return
+
+	ldr	lr, [fp, #-4]		@ restore LR from the stack
+	ldmia	sp, {r0-r11, ip, sp}	@ pop the saved registers INCLUDING
+					@ the stack pointer
+	ret	ip
+.endm
+
 #ifdef CONFIG_OLD_MCOUNT
 /*
  * mcount
@@ -312,14 +365,27 @@ UNWIND(.fnstart)
 	__ftrace_caller
 UNWIND(.fnend)
 ENDPROC(ftrace_caller)
+
+ENTRY(ftrace_regs_caller)
+UNWIND(.fnstart)
+	__ftrace_regs_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_regs_caller)
 #endif
 
+
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 ENTRY(ftrace_graph_caller)
 UNWIND(.fnstart)
 	__ftrace_graph_caller
 UNWIND(.fnend)
 ENDPROC(ftrace_graph_caller)
+
+ENTRY(ftrace_graph_regs_caller)
+UNWIND(.fnstart)
+	__ftrace_graph_regs_caller
+UNWIND(.fnend)
+ENDPROC(ftrace_graph_regs_caller)
 #endif
 
 .purgem mcount_enter
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index af9a8a9..35c5743 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -130,6 +130,16 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 	}
 #endif
 
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+	if (!ret) {
+		pc = (unsigned long)&ftrace_regs_call;
+		new = ftrace_call_replace(pc, (unsigned long)func);
+
+		ret = ftrace_modify_code(pc, 0, new, false);
+	}
+#endif
+
 	return ret;
 }
 
@@ -139,6 +149,20 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 	unsigned long ip = rec->ip;
 
 	old = ftrace_nop_replace(rec);
+
+	new = ftrace_call_replace(ip, adjust_address(rec, addr));
+
+	return ftrace_modify_code(rec->ip, old, new, true);
+}
+
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+				unsigned long addr)
+{
+	unsigned long new, old;
+	unsigned long ip = rec->ip;
+
+	old = ftrace_call_replace(ip, adjust_address(rec, old_addr));
+
 	new = ftrace_call_replace(ip, adjust_address(rec, addr));
 
 	return ftrace_modify_code(rec->ip, old, new, true);
@@ -211,6 +235,9 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 extern unsigned long ftrace_graph_call;
 extern unsigned long ftrace_graph_call_old;
 extern void ftrace_graph_caller_old(void);
+extern unsigned long ftrace_graph_regs_call;
+extern void ftrace_graph_regs_caller(void);
+
 
 static int __ftrace_modify_caller(unsigned long *callsite,
 				  void (*func) (void), bool enable)
@@ -240,6 +267,13 @@ static int ftrace_modify_graph_caller(bool enable)
 					     enable);
 #endif
 
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+	if (!ret)
+		ret = __ftrace_modify_caller(&ftrace_graph_regs_call,
+				     ftrace_graph_regs_caller,
+				     enable);
+#endif
+
 	return ret;
 }
 
-- 
2.1.3

Re: [PATCH] arm: ftrace: Adds support for ftrace operations

[Jean-Jacques Hiblot]

2014-11-07 18:01 GMT+01:00 Jean-Jacques Hiblot <jjhiblot@traphandler.com>:
>
>
> On 11/07/2014 05:52 PM, Steven Rostedt wrote:
>> On Fri,  7 Nov 2014 15:59:11 +0100
>> Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:
>>
>>> Hi all,
>>>
>>> This patch adds support for ftrace operations on the ARM architecture.
>>> This support is needed by kgraft and possibly other ftrace-based tools.
>>> My goal is to have kgraft working on ARM and aarch64.
>>
>> Can you add this to the change log of the patch. As that would be what
>> goes into git history. Because honestly, I had no idea what you meant
>> by "ftrace operations". If I don't understand that term, how can you
>> expect anyone else to?
> I'll try to come up with a clearer commit log.
>>
>>>
>>> I tested this patch with a toy implementation of kgraft for ARM and basic
>>> usage of function and function_graph tracers
>>> It doesn't show any problem with the ftrace selftests and the tests found
>>> today in branch ftrace/testing-mystuff of linux-trace repository
>>> (git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git)
>>
>> Those tests are no where near what I have. Does this code work on the
>> beagle bone white? If so, I can probably run my full suite on it.
> It should work on any arm processor, It's not platform or SOC dependent
>>
Hi Steve,
did you get a chance of running your tests suite on real hardware with
this patch? I'd be really interested in the results.

Jiri,
would you be interested in the patchs to run kgraft on ARM ? The
modifications required in kgraft core are minimal, it's mostly
architecture specific.

Jean-Jacques

>> -- Steve
>>
>>>
>>> Jean-Jacques Hiblot (1):
>>>   arm: ftrace: Adds support for ftrace operations
>>>
>>>  arch/arm/Kconfig               |  2 ++
>>>  arch/arm/include/asm/ftrace.h  |  3 ++
>>>  arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
>>>  arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
>>>  4 files changed, 106 insertions(+), 1 deletion(-)
>>>
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>

[PATCH] arm: ftrace: Adds support for ftrace operations

[Jean-Jacques Hiblot]

2014-11-07 18:01 GMT+01:00 Jean-Jacques Hiblot <jjhiblot@traphandler.com>:
>
>
> On 11/07/2014 05:52 PM, Steven Rostedt wrote:
>> On Fri,  7 Nov 2014 15:59:11 +0100
>> Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:
>>
>>> Hi all,
>>>
>>> This patch adds support for ftrace operations on the ARM architecture.
>>> This support is needed by kgraft and possibly other ftrace-based tools.
>>> My goal is to have kgraft working on ARM and aarch64.
>>
>> Can you add this to the change log of the patch. As that would be what
>> goes into git history. Because honestly, I had no idea what you meant
>> by "ftrace operations". If I don't understand that term, how can you
>> expect anyone else to?
> I'll try to come up with a clearer commit log.
>>
>>>
>>> I tested this patch with a toy implementation of kgraft for ARM and basic
>>> usage of function and function_graph tracers
>>> It doesn't show any problem with the ftrace selftests and the tests found
>>> today in branch ftrace/testing-mystuff of linux-trace repository
>>> (git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git)
>>
>> Those tests are no where near what I have. Does this code work on the
>> beagle bone white? If so, I can probably run my full suite on it.
> It should work on any arm processor, It's not platform or SOC dependent
>>
Hi Steve,
did you get a chance of running your tests suite on real hardware with
this patch? I'd be really interested in the results.

Jiri,
would you be interested in the patchs to run kgraft on ARM ? The
modifications required in kgraft core are minimal, it's mostly
architecture specific.

Jean-Jacques

>> -- Steve
>>
>>>
>>> Jean-Jacques Hiblot (1):
>>>   arm: ftrace: Adds support for ftrace operations
>>>
>>>  arch/arm/Kconfig               |  2 ++
>>>  arch/arm/include/asm/ftrace.h  |  3 ++
>>>  arch/arm/kernel/entry-common.S | 68 +++++++++++++++++++++++++++++++++++++++++-
>>>  arch/arm/kernel/ftrace.c       | 34 +++++++++++++++++++++
>>>  4 files changed, 106 insertions(+), 1 deletion(-)
>>>
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel at lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>

Re: [PATCH] arm: ftrace: Adds support for ftrace operations

[Steven Rostedt]

On Mon, 24 Nov 2014 10:59:24 +0100
Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:

> Hi Steve,
> did you get a chance of running your tests suite on real hardware with
> this patch? I'd be really interested in the results.

Yes I finally got it working on my beaglebone white. It passed all the
tests that passed without it. Although I'm not sure this patch itself
was tested as I didn't have kprobes which might use it.

-- Steve

[PATCH] arm: ftrace: Adds support for ftrace operations

[Steven Rostedt]

On Mon, 24 Nov 2014 10:59:24 +0100
Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:

> Hi Steve,
> did you get a chance of running your tests suite on real hardware with
> this patch? I'd be really interested in the results.

Yes I finally got it working on my beaglebone white. It passed all the
tests that passed without it. Although I'm not sure this patch itself
was tested as I didn't have kprobes which might use it.

-- Steve

Re: [PATCH] arm: ftrace: Adds support for ftrace operations

[Jean-Jacques Hiblot]

2014-11-26 0:20 GMT+01:00 Steven Rostedt <rostedt@goodmis.org>:
> On Mon, 24 Nov 2014 10:59:24 +0100
> Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:
>
>> Hi Steve,
>> did you get a chance of running your tests suite on real hardware with
>> this patch? I'd be really interested in the results.
>
> Yes I finally got it working on my beaglebone white. It passed all the
> tests that passed without it. Although I'm not sure this patch itself
> was tested as I didn't have kprobes which might use it.
>
Thanks for testing it. At least it doesn't cause regression.
What do you mean by not having krpobes which might use it ? Are you
thinking of the kprobe optimization based on ftrace ?

JJ

> -- Steve
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH] arm: ftrace: Adds support for ftrace operations

[Jean-Jacques Hiblot]

2014-11-26 0:20 GMT+01:00 Steven Rostedt <rostedt@goodmis.org>:
> On Mon, 24 Nov 2014 10:59:24 +0100
> Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:
>
>> Hi Steve,
>> did you get a chance of running your tests suite on real hardware with
>> this patch? I'd be really interested in the results.
>
> Yes I finally got it working on my beaglebone white. It passed all the
> tests that passed without it. Although I'm not sure this patch itself
> was tested as I didn't have kprobes which might use it.
>
Thanks for testing it. At least it doesn't cause regression.
What do you mean by not having krpobes which might use it ? Are you
thinking of the kprobe optimization based on ftrace ?

JJ

> -- Steve
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH] arm: ftrace: Adds support for ftrace operations

[Steven Rostedt]

On Thu, 27 Nov 2014 11:23:45 +0100
Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:

> 2014-11-26 0:20 GMT+01:00 Steven Rostedt <rostedt@goodmis.org>:
> > On Mon, 24 Nov 2014 10:59:24 +0100
> > Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:
> >
> >> Hi Steve,
> >> did you get a chance of running your tests suite on real hardware with
> >> this patch? I'd be really interested in the results.
> >
> > Yes I finally got it working on my beaglebone white. It passed all the
> > tests that passed without it. Although I'm not sure this patch itself
> > was tested as I didn't have kprobes which might use it.
> >
> Thanks for testing it. At least it doesn't cause regression.
> What do you mean by not having krpobes which might use it ? Are you
> thinking of the kprobe optimization based on ftrace ?
> 

Yep. My tests use that. But as ARM doesn't have an mfentry where
functions probed by kprobes at the start are optimized with ftrace, my
tests wont test it.

I also didn't have kprobes enabled on this board. Is it fully supported
in ARM, and does kprobes use it there too?

-- Steve

[PATCH] arm: ftrace: Adds support for ftrace operations

[Steven Rostedt]

On Thu, 27 Nov 2014 11:23:45 +0100
Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:

> 2014-11-26 0:20 GMT+01:00 Steven Rostedt <rostedt@goodmis.org>:
> > On Mon, 24 Nov 2014 10:59:24 +0100
> > Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote:
> >
> >> Hi Steve,
> >> did you get a chance of running your tests suite on real hardware with
> >> this patch? I'd be really interested in the results.
> >
> > Yes I finally got it working on my beaglebone white. It passed all the
> > tests that passed without it. Although I'm not sure this patch itself
> > was tested as I didn't have kprobes which might use it.
> >
> Thanks for testing it. At least it doesn't cause regression.
> What do you mean by not having krpobes which might use it ? Are you
> thinking of the kprobe optimization based on ftrace ?
> 

Yep. My tests use that. But as ARM doesn't have an mfentry where
functions probed by kprobes at the start are optimized with ftrace, my
tests wont test it.

I also didn't have kprobes enabled on this board. Is it fully supported
in ARM, and does kprobes use it there too?

-- Steve