2023-03-28 13:49:38

by pengdonglin

Subject: [PATCH v8 3/8] ARM: ftrace: Enable HAVE_FUNCTION_GRAPH_RETVAL

The commit d4815c5d1bbd ("function_graph: Support recording and printing
the return value of function") laid the groundwork for the for the
funcgraph-retval, and this modification makes it available on the
ARM platform.

We introduce a new structure called fgraph_ret_regs for the ARM platform
to hold return registers and the frame pointer. We then fill its content
in the return_to_handler and pass its address to the function
ftrace_return_to_handler to record the return value.

Signed-off-by: Donglin Peng <[email protected]>
---
v8:
- Modify the control range of CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
---
arch/arm/Kconfig | 1 +
arch/arm/include/asm/ftrace.h | 18 ++++++++++++++++++
arch/arm/kernel/entry-ftrace.S | 6 +++++-
3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index e24a9820e12f..73061379855a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -98,6 +98,7 @@ config ARM
select HAVE_FAST_GUP if ARM_LPAE
select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
select HAVE_FUNCTION_ERROR_INJECTION
+ select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER if !XIP_KERNEL
select HAVE_GCC_PLUGINS
diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 7e9251ca29fe..2ab4bee21d79 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -77,4 +77,22 @@ static inline bool arch_syscall_match_sym_name(const char *sym,

#endif /* ifndef __ASSEMBLY__ */

+
+#ifndef __ASSEMBLY__
+struct fgraph_ret_regs {
+ unsigned long regs[4];
+ unsigned long fp;
+};
+
+static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
+{
+ return ret_regs->regs[0];
+}
+
+static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
+{
+ return ret_regs->fp;
+}
+#endif
+
#endif /* _ASM_ARM_FTRACE */
diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S
index 3e7bcaca5e07..5f1e74555b25 100644
--- a/arch/arm/kernel/entry-ftrace.S
+++ b/arch/arm/kernel/entry-ftrace.S
@@ -257,11 +257,15 @@ ENDPROC(ftrace_graph_regs_caller)

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(return_to_handler)
+ sub sp, sp, #4
stmdb sp!, {r0-r3}
- add r0, sp, #16 @ sp at exit of instrumented routine
+ add r0, sp, #20 @ sp at exit of instrumented routine
+ str r0, [sp, #16]
+ mov r0, sp
bl ftrace_return_to_handler
mov lr, r0 @ r0 has real ret addr
ldmia sp!, {r0-r3}
+ add sp, sp, #4 @ skip fp
ret lr
ENDPROC(return_to_handler)
#endif
--
2.25.1

2023-03-28 14:07:35

by Russell King (Oracle)

Subject: Re: [PATCH v8 3/8] ARM: ftrace: Enable HAVE_FUNCTION_GRAPH_RETVAL

On Tue, Mar 28, 2023 at 06:43:14AM -0700, Donglin Peng wrote:
> The commit d4815c5d1bbd ("function_graph: Support recording and printing
> the return value of function") laid the groundwork for the for the
> funcgraph-retval, and this modification makes it available on the
> ARM platform.
>
> We introduce a new structure called fgraph_ret_regs for the ARM platform
> to hold return registers and the frame pointer. We then fill its content
> in the return_to_handler and pass its address to the function
> ftrace_return_to_handler to record the return value.
>
> Signed-off-by: Donglin Peng <[email protected]>
> ---
> v8:
> - Modify the control range of CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
> ---
> arch/arm/Kconfig | 1 +
> arch/arm/include/asm/ftrace.h | 18 ++++++++++++++++++
> arch/arm/kernel/entry-ftrace.S | 6 +++++-
> 3 files changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index e24a9820e12f..73061379855a 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -98,6 +98,7 @@ config ARM
> select HAVE_FAST_GUP if ARM_LPAE
> select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
> select HAVE_FUNCTION_ERROR_INJECTION
> + select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
> select HAVE_FUNCTION_GRAPH_TRACER
> select HAVE_FUNCTION_TRACER if !XIP_KERNEL
> select HAVE_GCC_PLUGINS
> diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
> index 7e9251ca29fe..2ab4bee21d79 100644
> --- a/arch/arm/include/asm/ftrace.h
> +++ b/arch/arm/include/asm/ftrace.h
> @@ -77,4 +77,22 @@ static inline bool arch_syscall_match_sym_name(const char *sym,
>
> #endif /* ifndef __ASSEMBLY__ */
>
> +
> +#ifndef __ASSEMBLY__
> +struct fgraph_ret_regs {
> + unsigned long regs[4];
> + unsigned long fp;
> +};
> +
> +static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
> +{
> + return ret_regs->regs[0];
> +}
> +
> +static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
> +{
> + return ret_regs->fp;
> +}
> +#endif
> +
> #endif /* _ASM_ARM_FTRACE */
> diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S
> index 3e7bcaca5e07..5f1e74555b25 100644
> --- a/arch/arm/kernel/entry-ftrace.S
> +++ b/arch/arm/kernel/entry-ftrace.S
> @@ -257,11 +257,15 @@ ENDPROC(ftrace_graph_regs_caller)
>
> #ifdef CONFIG_FUNCTION_GRAPH_TRACER
> ENTRY(return_to_handler)
> + sub sp, sp, #4
> stmdb sp!, {r0-r3}
> - add r0, sp, #16 @ sp at exit of instrumented routine
> + add r0, sp, #20 @ sp at exit of instrumented routine
> + str r0, [sp, #16]
> + mov r0, sp

1) EABI wants the stack to be aligned to 8 bytes.
2) We can do better than this.

mov ip, sp
stmdb sp!, {r0-r3, ip, lr}
mov r0, sp

> bl ftrace_return_to_handler
> mov lr, r0 @ r0 has real ret addr
> ldmia sp!, {r0-r3}

ldmia sp, {r0-r3} @ since we need to manually adjust sp,

> + add sp, sp, #4 @ skip fp

add sp, sp, #4 * 6 @ restore stack pointer here

> ret lr
> ENDPROC(return_to_handler)
> #endif
> --
> 2.25.1
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>

--
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2023-03-29 01:18:03

by pengdonglin

Subject: Re: [PATCH v8 3/8] ARM: ftrace: Enable HAVE_FUNCTION_GRAPH_RETVAL

On 2023/3/28 22:02, Russell King (Oracle) wrote:
> On Tue, Mar 28, 2023 at 06:43:14AM -0700, Donglin Peng wrote:
>> The commit d4815c5d1bbd ("function_graph: Support recording and printing
>> the return value of function") laid the groundwork for the for the
>> funcgraph-retval, and this modification makes it available on the
>> ARM platform.
>>
>> We introduce a new structure called fgraph_ret_regs for the ARM platform
>> to hold return registers and the frame pointer. We then fill its content
>> in the return_to_handler and pass its address to the function
>> ftrace_return_to_handler to record the return value.
>>
>> Signed-off-by: Donglin Peng <[email protected]>
>> ---
>> v8:
>> - Modify the control range of CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
>> ---
>> arch/arm/Kconfig | 1 +
>> arch/arm/include/asm/ftrace.h | 18 ++++++++++++++++++
>> arch/arm/kernel/entry-ftrace.S | 6 +++++-
>> 3 files changed, 24 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
>> index e24a9820e12f..73061379855a 100644
>> --- a/arch/arm/Kconfig
>> +++ b/arch/arm/Kconfig
>> @@ -98,6 +98,7 @@ config ARM
>> select HAVE_FAST_GUP if ARM_LPAE
>> select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
>> select HAVE_FUNCTION_ERROR_INJECTION
>> + select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
>> select HAVE_FUNCTION_GRAPH_TRACER
>> select HAVE_FUNCTION_TRACER if !XIP_KERNEL
>> select HAVE_GCC_PLUGINS
>> diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
>> index 7e9251ca29fe..2ab4bee21d79 100644
>> --- a/arch/arm/include/asm/ftrace.h
>> +++ b/arch/arm/include/asm/ftrace.h
>> @@ -77,4 +77,22 @@ static inline bool arch_syscall_match_sym_name(const char *sym,
>>
>> #endif /* ifndef __ASSEMBLY__ */
>>
>> +
>> +#ifndef __ASSEMBLY__
>> +struct fgraph_ret_regs {
>> + unsigned long regs[4];
>> + unsigned long fp;
>> +};
>> +
>> +static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
>> +{
>> + return ret_regs->regs[0];
>> +}
>> +
>> +static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
>> +{
>> + return ret_regs->fp;
>> +}
>> +#endif
>> +
>> #endif /* _ASM_ARM_FTRACE */
>> diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S
>> index 3e7bcaca5e07..5f1e74555b25 100644
>> --- a/arch/arm/kernel/entry-ftrace.S
>> +++ b/arch/arm/kernel/entry-ftrace.S
>> @@ -257,11 +257,15 @@ ENDPROC(ftrace_graph_regs_caller)
>>
>> #ifdef CONFIG_FUNCTION_GRAPH_TRACER
>> ENTRY(return_to_handler)
>> + sub sp, sp, #4
>> stmdb sp!, {r0-r3}
>> - add r0, sp, #16 @ sp at exit of instrumented routine
>> + add r0, sp, #20 @ sp at exit of instrumented routine
>> + str r0, [sp, #16]
>> + mov r0, sp
>
> 1) EABI wants the stack to be aligned to 8 bytes.
> 2) We can do better than this.
>
> mov ip, sp
> stmdb sp!, {r0-r3, ip, lr}
> mov r0, sp

Great, I will modify it.

>
>> bl ftrace_return_to_handler
>> mov lr, r0 @ r0 has real ret addr
>> ldmia sp!, {r0-r3}
>
> ldmia sp, {r0-r3} @ since we need to manually adjust sp,

Thanks, I will modify it.

>
>> + add sp, sp, #4 @ skip fp
>
> add sp, sp, #4 * 6 @ restore stack pointer here

Thanks, I will modify it.

>
>> ret lr
>> ENDPROC(return_to_handler)
>> #endif
>> --
>> 2.25.1
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> [email protected]
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
>