[PATCH RESEND v3 1/2] ftrace: cleanup ftrace_graph_caller enable and disable

[PATCH RESEND v3 1/2] ftrace: cleanup ftrace_graph_caller enable and disable

[Chengming Zhou]

The ftrace_[enable,disable]_ftrace_graph_caller() are used to do
special hooks for graph tracer, which are not needed on some ARCHs
that use graph_ops:func function to install return_hooker.

So introduce the weak version in ftrace core code to cleanup
in x86.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
v3:
 - consolidate two #if into a single #if, suggested by Steve. Thanks.
---
 arch/x86/kernel/ftrace.c | 17 ++---------------
 kernel/trace/ftrace.c    | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 1e31c7d21597..b09d73c2ba89 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -579,9 +579,7 @@ void arch_ftrace_trampoline_free(struct ftrace_ops *ops)
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 
-#ifdef CONFIG_DYNAMIC_FTRACE
-
-#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+#if defined(CONFIG_DYNAMIC_FTRACE) && !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS)
 extern void ftrace_graph_call(void);
 static const char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
 {
@@ -610,18 +608,7 @@ int ftrace_disable_ftrace_graph_caller(void)
 
 	return ftrace_mod_jmp(ip, &ftrace_stub);
 }
-#else /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
-int ftrace_enable_ftrace_graph_caller(void)
-{
-	return 0;
-}
-
-int ftrace_disable_ftrace_graph_caller(void)
-{
-	return 0;
-}
-#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
-#endif /* !CONFIG_DYNAMIC_FTRACE */
+#endif /* CONFIG_DYNAMIC_FTRACE && !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
 
 /*
  * Hook the return address and push it in the stack of return addrs
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 4f1d2f5e7263..30622c755c77 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2721,6 +2721,26 @@ int __weak ftrace_arch_code_modify_post_process(void)
 	return 0;
 }
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+/*
+ * archs can override this function if they must do something
+ * to enable hook for graph tracer.
+ */
+int __weak ftrace_enable_ftrace_graph_caller(void)
+{
+	return 0;
+}
+
+/*
+ * archs can override this function if they must do something
+ * to disable hook for graph tracer.
+ */
+int __weak ftrace_disable_ftrace_graph_caller(void)
+{
+	return 0;
+}
+#endif
+
 void ftrace_modify_all_code(int command)
 {
 	int update = command & FTRACE_UPDATE_TRACE_FUNC;
-- 
2.20.1


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[PATCH RESEND v3 1/2] ftrace: cleanup ftrace_graph_caller enable and disable

[Chengming Zhou]

The ftrace_[enable,disable]_ftrace_graph_caller() are used to do
special hooks for graph tracer, which are not needed on some ARCHs
that use graph_ops:func function to install return_hooker.

So introduce the weak version in ftrace core code to cleanup
in x86.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
v3:
 - consolidate two #if into a single #if, suggested by Steve. Thanks.
---
 arch/x86/kernel/ftrace.c | 17 ++---------------
 kernel/trace/ftrace.c    | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 1e31c7d21597..b09d73c2ba89 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -579,9 +579,7 @@ void arch_ftrace_trampoline_free(struct ftrace_ops *ops)
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 
-#ifdef CONFIG_DYNAMIC_FTRACE
-
-#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+#if defined(CONFIG_DYNAMIC_FTRACE) && !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS)
 extern void ftrace_graph_call(void);
 static const char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
 {
@@ -610,18 +608,7 @@ int ftrace_disable_ftrace_graph_caller(void)
 
 	return ftrace_mod_jmp(ip, &ftrace_stub);
 }
-#else /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
-int ftrace_enable_ftrace_graph_caller(void)
-{
-	return 0;
-}
-
-int ftrace_disable_ftrace_graph_caller(void)
-{
-	return 0;
-}
-#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
-#endif /* !CONFIG_DYNAMIC_FTRACE */
+#endif /* CONFIG_DYNAMIC_FTRACE && !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
 
 /*
  * Hook the return address and push it in the stack of return addrs
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 4f1d2f5e7263..30622c755c77 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2721,6 +2721,26 @@ int __weak ftrace_arch_code_modify_post_process(void)
 	return 0;
 }
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+/*
+ * archs can override this function if they must do something
+ * to enable hook for graph tracer.
+ */
+int __weak ftrace_enable_ftrace_graph_caller(void)
+{
+	return 0;
+}
+
+/*
+ * archs can override this function if they must do something
+ * to disable hook for graph tracer.
+ */
+int __weak ftrace_disable_ftrace_graph_caller(void)
+{
+	return 0;
+}
+#endif
+
 void ftrace_modify_all_code(int command)
 {
 	int update = command & FTRACE_UPDATE_TRACE_FUNC;
-- 
2.20.1

[PATCH RESEND v3 2/2] arm64/ftrace: Make function graph use ftrace directly

[Chengming Zhou]

As we do in commit 0c0593b45c9b ("x86/ftrace: Make function graph
use ftrace directly"), we don't need special hook for graph tracer,
but instead we use graph_ops:func function to install return_hooker.

Since commit 3b23e4991fb6 ("arm64: implement ftrace with regs") add
implementation for FTRACE_WITH_REGS on arm64, we can easily adopt
the same cleanup on arm64.

And this cleanup only changes the FTRACE_WITH_REGS implementation,
so the mcount-based implementation is unaffected.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
v3:
 - Add comments in ftrace_graph_func() as suggested by Steve. Thanks.

v2:
 - Remove FTRACE_WITH_REGS ftrace_graph_caller asm, thanks Mark.
---
 arch/arm64/include/asm/ftrace.h  |  7 +++++++
 arch/arm64/kernel/entry-ftrace.S | 17 -----------------
 arch/arm64/kernel/ftrace.c       | 17 +++++++++++++++++
 3 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index 1494cfa8639b..dbc45a4157fa 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -80,8 +80,15 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
 
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 struct dyn_ftrace;
+struct ftrace_ops;
+struct ftrace_regs;
+
 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
 #define ftrace_init_nop ftrace_init_nop
+
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+		       struct ftrace_ops *op, struct ftrace_regs *fregs);
+#define ftrace_graph_func ftrace_graph_func
 #endif
 
 #define ftrace_return_address(n) return_address(n)
diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S
index e535480a4069..d42a205ef625 100644
--- a/arch/arm64/kernel/entry-ftrace.S
+++ b/arch/arm64/kernel/entry-ftrace.S
@@ -97,12 +97,6 @@ SYM_CODE_START(ftrace_common)
 SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)
 	bl	ftrace_stub
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-SYM_INNER_LABEL(ftrace_graph_call, SYM_L_GLOBAL) // ftrace_graph_caller();
-	nop				// If enabled, this will be replaced
-					// "b ftrace_graph_caller"
-#endif
-
 /*
  * At the callsite x0-x8 and x19-x30 were live. Any C code will have preserved
  * x19-x29 per the AAPCS, and we created frame records upon entry, so we need
@@ -127,17 +121,6 @@ ftrace_common_return:
 	ret	x9
 SYM_CODE_END(ftrace_common)
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-SYM_CODE_START(ftrace_graph_caller)
-	ldr	x0, [sp, #S_PC]
-	sub	x0, x0, #AARCH64_INSN_SIZE	// ip (callsite's BL insn)
-	add	x1, sp, #S_LR			// parent_ip (callsite's LR)
-	ldr	x2, [sp, #PT_REGS_SIZE]	   	// parent fp (callsite's FP)
-	bl	prepare_ftrace_return
-	b	ftrace_common_return
-SYM_CODE_END(ftrace_graph_caller)
-#endif
-
 #else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
 
 /*
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 4506c4a90ac1..35eb7c9b5e53 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -268,6 +268,22 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+		       struct ftrace_ops *op, struct ftrace_regs *fregs)
+{
+	/*
+	 * Athough graph_ops doesn't have FTRACE_OPS_FL_SAVE_REGS set in flags,
+	 * regs can't be NULL in DYNAMIC_FTRACE_WITH_REGS. By design, it should
+	 * be fixed when DYNAMIC_FTRACE_WITH_ARGS is implemented.
+	 */
+	struct pt_regs *regs = arch_ftrace_get_regs(fregs);
+	unsigned long *parent = (unsigned long *)&procedure_link_pointer(regs);
+
+	prepare_ftrace_return(ip, parent, frame_pointer(regs));
+}
+#else
 /*
  * Turn on/off the call to ftrace_graph_caller() in ftrace_caller()
  * depending on @enable.
@@ -297,5 +313,6 @@ int ftrace_disable_ftrace_graph_caller(void)
 {
 	return ftrace_modify_graph_caller(false);
 }
+#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
 #endif /* CONFIG_DYNAMIC_FTRACE */
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
-- 
2.20.1


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[PATCH RESEND v3 2/2] arm64/ftrace: Make function graph use ftrace directly

[Chengming Zhou]

As we do in commit 0c0593b45c9b ("x86/ftrace: Make function graph
use ftrace directly"), we don't need special hook for graph tracer,
but instead we use graph_ops:func function to install return_hooker.

Since commit 3b23e4991fb6 ("arm64: implement ftrace with regs") add
implementation for FTRACE_WITH_REGS on arm64, we can easily adopt
the same cleanup on arm64.

And this cleanup only changes the FTRACE_WITH_REGS implementation,
so the mcount-based implementation is unaffected.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
v3:
 - Add comments in ftrace_graph_func() as suggested by Steve. Thanks.

v2:
 - Remove FTRACE_WITH_REGS ftrace_graph_caller asm, thanks Mark.
---
 arch/arm64/include/asm/ftrace.h  |  7 +++++++
 arch/arm64/kernel/entry-ftrace.S | 17 -----------------
 arch/arm64/kernel/ftrace.c       | 17 +++++++++++++++++
 3 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index 1494cfa8639b..dbc45a4157fa 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -80,8 +80,15 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
 
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 struct dyn_ftrace;
+struct ftrace_ops;
+struct ftrace_regs;
+
 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
 #define ftrace_init_nop ftrace_init_nop
+
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+		       struct ftrace_ops *op, struct ftrace_regs *fregs);
+#define ftrace_graph_func ftrace_graph_func
 #endif
 
 #define ftrace_return_address(n) return_address(n)
diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S
index e535480a4069..d42a205ef625 100644
--- a/arch/arm64/kernel/entry-ftrace.S
+++ b/arch/arm64/kernel/entry-ftrace.S
@@ -97,12 +97,6 @@ SYM_CODE_START(ftrace_common)
 SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)
 	bl	ftrace_stub
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-SYM_INNER_LABEL(ftrace_graph_call, SYM_L_GLOBAL) // ftrace_graph_caller();
-	nop				// If enabled, this will be replaced
-					// "b ftrace_graph_caller"
-#endif
-
 /*
  * At the callsite x0-x8 and x19-x30 were live. Any C code will have preserved
  * x19-x29 per the AAPCS, and we created frame records upon entry, so we need
@@ -127,17 +121,6 @@ ftrace_common_return:
 	ret	x9
 SYM_CODE_END(ftrace_common)
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-SYM_CODE_START(ftrace_graph_caller)
-	ldr	x0, [sp, #S_PC]
-	sub	x0, x0, #AARCH64_INSN_SIZE	// ip (callsite's BL insn)
-	add	x1, sp, #S_LR			// parent_ip (callsite's LR)
-	ldr	x2, [sp, #PT_REGS_SIZE]	   	// parent fp (callsite's FP)
-	bl	prepare_ftrace_return
-	b	ftrace_common_return
-SYM_CODE_END(ftrace_graph_caller)
-#endif
-
 #else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
 
 /*
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 4506c4a90ac1..35eb7c9b5e53 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -268,6 +268,22 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+		       struct ftrace_ops *op, struct ftrace_regs *fregs)
+{
+	/*
+	 * Athough graph_ops doesn't have FTRACE_OPS_FL_SAVE_REGS set in flags,
+	 * regs can't be NULL in DYNAMIC_FTRACE_WITH_REGS. By design, it should
+	 * be fixed when DYNAMIC_FTRACE_WITH_ARGS is implemented.
+	 */
+	struct pt_regs *regs = arch_ftrace_get_regs(fregs);
+	unsigned long *parent = (unsigned long *)&procedure_link_pointer(regs);
+
+	prepare_ftrace_return(ip, parent, frame_pointer(regs));
+}
+#else
 /*
  * Turn on/off the call to ftrace_graph_caller() in ftrace_caller()
  * depending on @enable.
@@ -297,5 +313,6 @@ int ftrace_disable_ftrace_graph_caller(void)
 {
 	return ftrace_modify_graph_caller(false);
 }
+#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
 #endif /* CONFIG_DYNAMIC_FTRACE */
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
-- 
2.20.1

Re: [PATCH RESEND v3 1/2] ftrace: cleanup ftrace_graph_caller enable and disable

[Steven Rostedt]

On Sat,  9 Apr 2022 16:54:59 +0800
Chengming Zhou <zhouchengming@bytedance.com> wrote:

> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -2721,6 +2721,26 @@ int __weak ftrace_arch_code_modify_post_process(void)
>  	return 0;
>  }
>  
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER

Actually, can you put this into fgraph.c instead. That only gets compiled
if the above config is enabled. Thus, you do not even need to add the
#ifdef around it.

I intend to move even more code into fgraph.c that is only for function
graph. I don't want to add any new code to ftrace.c for it.

-- Steve


> +/*
> + * archs can override this function if they must do something
> + * to enable hook for graph tracer.
> + */
> +int __weak ftrace_enable_ftrace_graph_caller(void)
> +{
> +	return 0;
> +}
> +
> +/*
> + * archs can override this function if they must do something
> + * to disable hook for graph tracer.
> + */
> +int __weak ftrace_disable_ftrace_graph_caller(void)
> +{
> +	return 0;
> +}
> +#endif
> +
>  void ftrace_modify_all_code(int command)
>  {
>  	int update = command & FTRACE_UPDATE_TRACE_FUNC;

Re: [PATCH RESEND v3 1/2] ftrace: cleanup ftrace_graph_caller enable and disable

[Steven Rostedt]

On Sat,  9 Apr 2022 16:54:59 +0800
Chengming Zhou <zhouchengming@bytedance.com> wrote:

> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -2721,6 +2721,26 @@ int __weak ftrace_arch_code_modify_post_process(void)
>  	return 0;
>  }
>  
> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER

Actually, can you put this into fgraph.c instead. That only gets compiled
if the above config is enabled. Thus, you do not even need to add the
#ifdef around it.

I intend to move even more code into fgraph.c that is only for function
graph. I don't want to add any new code to ftrace.c for it.

-- Steve


> +/*
> + * archs can override this function if they must do something
> + * to enable hook for graph tracer.
> + */
> +int __weak ftrace_enable_ftrace_graph_caller(void)
> +{
> +	return 0;
> +}
> +
> +/*
> + * archs can override this function if they must do something
> + * to disable hook for graph tracer.
> + */
> +int __weak ftrace_disable_ftrace_graph_caller(void)
> +{
> +	return 0;
> +}
> +#endif
> +
>  void ftrace_modify_all_code(int command)
>  {
>  	int update = command & FTRACE_UPDATE_TRACE_FUNC;


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Re: [External] Re: [PATCH RESEND v3 1/2] ftrace: cleanup ftrace_graph_caller enable and disable

[Chengming Zhou]

On 2022/4/9 22:23, Steven Rostedt wrote:
> On Sat,  9 Apr 2022 16:54:59 +0800
> Chengming Zhou <zhouchengming@bytedance.com> wrote:
> 
>> --- a/kernel/trace/ftrace.c
>> +++ b/kernel/trace/ftrace.c
>> @@ -2721,6 +2721,26 @@ int __weak ftrace_arch_code_modify_post_process(void)
>>  	return 0;
>>  }
>>  
>> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> 
> Actually, can you put this into fgraph.c instead. That only gets compiled
> if the above config is enabled. Thus, you do not even need to add the
> #ifdef around it.
> 
> I intend to move even more code into fgraph.c that is only for function
> graph. I don't want to add any new code to ftrace.c for it.

Ok, make sense. I will do it.

Thanks.

> 
> -- Steve
> 
> 
>> +/*
>> + * archs can override this function if they must do something
>> + * to enable hook for graph tracer.
>> + */
>> +int __weak ftrace_enable_ftrace_graph_caller(void)
>> +{
>> +	return 0;
>> +}
>> +
>> +/*
>> + * archs can override this function if they must do something
>> + * to disable hook for graph tracer.
>> + */
>> +int __weak ftrace_disable_ftrace_graph_caller(void)
>> +{
>> +	return 0;
>> +}
>> +#endif
>> +
>>  void ftrace_modify_all_code(int command)
>>  {
>>  	int update = command & FTRACE_UPDATE_TRACE_FUNC;
> 

Re: [External] Re: [PATCH RESEND v3 1/2] ftrace: cleanup ftrace_graph_caller enable and disable

[Chengming Zhou]

On 2022/4/9 22:23, Steven Rostedt wrote:
> On Sat,  9 Apr 2022 16:54:59 +0800
> Chengming Zhou <zhouchengming@bytedance.com> wrote:
> 
>> --- a/kernel/trace/ftrace.c
>> +++ b/kernel/trace/ftrace.c
>> @@ -2721,6 +2721,26 @@ int __weak ftrace_arch_code_modify_post_process(void)
>>  	return 0;
>>  }
>>  
>> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> 
> Actually, can you put this into fgraph.c instead. That only gets compiled
> if the above config is enabled. Thus, you do not even need to add the
> #ifdef around it.
> 
> I intend to move even more code into fgraph.c that is only for function
> graph. I don't want to add any new code to ftrace.c for it.

Ok, make sense. I will do it.

Thanks.

> 
> -- Steve
> 
> 
>> +/*
>> + * archs can override this function if they must do something
>> + * to enable hook for graph tracer.
>> + */
>> +int __weak ftrace_enable_ftrace_graph_caller(void)
>> +{
>> +	return 0;
>> +}
>> +
>> +/*
>> + * archs can override this function if they must do something
>> + * to disable hook for graph tracer.
>> + */
>> +int __weak ftrace_disable_ftrace_graph_caller(void)
>> +{
>> +	return 0;
>> +}
>> +#endif
>> +
>>  void ftrace_modify_all_code(int command)
>>  {
>>  	int update = command & FTRACE_UPDATE_TRACE_FUNC;
> 

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