Correct perf sampling with guest VMs

[PATCH 1/5] arm: perf: Drop unused functions

Posted by Colton Lewis 1 year, 3 months ago

perf_instruction_pointer() and perf_misc_flags() aren't used anywhere
in this particular perf implementation. Drop them.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
---
 arch/arm/include/asm/perf_event.h |  7 -------
 arch/arm/kernel/perf_callchain.c  | 17 -----------------
 2 files changed, 24 deletions(-)

diff --git a/arch/arm/include/asm/perf_event.h b/arch/arm/include/asm/perf_event.h
index bdbc1e590891..c08f16f2e243 100644
--- a/arch/arm/include/asm/perf_event.h
+++ b/arch/arm/include/asm/perf_event.h
@@ -8,13 +8,6 @@
 #ifndef __ARM_PERF_EVENT_H__
 #define __ARM_PERF_EVENT_H__
 
-#ifdef CONFIG_PERF_EVENTS
-struct pt_regs;
-extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
-extern unsigned long perf_misc_flags(struct pt_regs *regs);
-#define perf_misc_flags(regs)	perf_misc_flags(regs)
-#endif
-
 #define perf_arch_fetch_caller_regs(regs, __ip) { \
 	(regs)->ARM_pc = (__ip); \
 	frame_pointer((regs)) = (unsigned long) __builtin_frame_address(0); \
diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c
index 1d230ac9d0eb..a2601b1ef318 100644
--- a/arch/arm/kernel/perf_callchain.c
+++ b/arch/arm/kernel/perf_callchain.c
@@ -96,20 +96,3 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
 	arm_get_current_stackframe(regs, &fr);
 	walk_stackframe(&fr, callchain_trace, entry);
 }
-
-unsigned long perf_instruction_pointer(struct pt_regs *regs)
-{
-	return instruction_pointer(regs);
-}
-
-unsigned long perf_misc_flags(struct pt_regs *regs)
-{
-	int misc = 0;
-
-	if (user_mode(regs))
-		misc |= PERF_RECORD_MISC_USER;
-	else
-		misc |= PERF_RECORD_MISC_KERNEL;
-
-	return misc;
-}
-- 
2.46.0.469.g59c65b2a67-goog

Re: [PATCH 1/5] arm: perf: Drop unused functions

Posted by Mark Rutland 1 year, 3 months ago

On Wed, Sep 04, 2024 at 08:41:29PM +0000, Colton Lewis wrote:
> perf_instruction_pointer() and perf_misc_flags() aren't used anywhere
> in this particular perf implementation. Drop them.

I think it'd be better to say that arch/arm's implementation of these is
equivalent to the generic versions in include/linux/perf_event.h, and so
arch/arm doesn't need to provide its own versions. It doesn't matter if
arch/arm uses them itself since they're being provided for the core perf
code.

With words to that effect:

Acked-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> 
> Signed-off-by: Colton Lewis <coltonlewis@google.com>
> ---
>  arch/arm/include/asm/perf_event.h |  7 -------
>  arch/arm/kernel/perf_callchain.c  | 17 -----------------
>  2 files changed, 24 deletions(-)
> 
> diff --git a/arch/arm/include/asm/perf_event.h b/arch/arm/include/asm/perf_event.h
> index bdbc1e590891..c08f16f2e243 100644
> --- a/arch/arm/include/asm/perf_event.h
> +++ b/arch/arm/include/asm/perf_event.h
> @@ -8,13 +8,6 @@
>  #ifndef __ARM_PERF_EVENT_H__
>  #define __ARM_PERF_EVENT_H__
>  
> -#ifdef CONFIG_PERF_EVENTS
> -struct pt_regs;
> -extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
> -extern unsigned long perf_misc_flags(struct pt_regs *regs);
> -#define perf_misc_flags(regs)	perf_misc_flags(regs)
> -#endif
> -
>  #define perf_arch_fetch_caller_regs(regs, __ip) { \
>  	(regs)->ARM_pc = (__ip); \
>  	frame_pointer((regs)) = (unsigned long) __builtin_frame_address(0); \
> diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c
> index 1d230ac9d0eb..a2601b1ef318 100644
> --- a/arch/arm/kernel/perf_callchain.c
> +++ b/arch/arm/kernel/perf_callchain.c
> @@ -96,20 +96,3 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
>  	arm_get_current_stackframe(regs, &fr);
>  	walk_stackframe(&fr, callchain_trace, entry);
>  }
> -
> -unsigned long perf_instruction_pointer(struct pt_regs *regs)
> -{
> -	return instruction_pointer(regs);
> -}
> -
> -unsigned long perf_misc_flags(struct pt_regs *regs)
> -{
> -	int misc = 0;
> -
> -	if (user_mode(regs))
> -		misc |= PERF_RECORD_MISC_USER;
> -	else
> -		misc |= PERF_RECORD_MISC_KERNEL;
> -
> -	return misc;
> -}
> -- 
> 2.46.0.469.g59c65b2a67-goog
>

Re: [PATCH 1/5] arm: perf: Drop unused functions

Posted by Colton Lewis 1 year, 3 months ago

Mark Rutland <mark.rutland@arm.com> writes:

> On Wed, Sep 04, 2024 at 08:41:29PM +0000, Colton Lewis wrote:
>> perf_instruction_pointer() and perf_misc_flags() aren't used anywhere
>> in this particular perf implementation. Drop them.

> I think it'd be better to say that arch/arm's implementation of these is
> equivalent to the generic versions in include/linux/perf_event.h, and so
> arch/arm doesn't need to provide its own versions. It doesn't matter if
> arch/arm uses them itself since they're being provided for the core perf
> code.

> With words to that effect:

Done

> Acked-by: Mark Rutland <mark.rutland@arm.com>

> Mark.


>> Signed-off-by: Colton Lewis <coltonlewis@google.com>
>> ---
>>   arch/arm/include/asm/perf_event.h |  7 -------
>>   arch/arm/kernel/perf_callchain.c  | 17 -----------------
>>   2 files changed, 24 deletions(-)

>> diff --git a/arch/arm/include/asm/perf_event.h  
>> b/arch/arm/include/asm/perf_event.h
>> index bdbc1e590891..c08f16f2e243 100644
>> --- a/arch/arm/include/asm/perf_event.h
>> +++ b/arch/arm/include/asm/perf_event.h
>> @@ -8,13 +8,6 @@
>>   #ifndef __ARM_PERF_EVENT_H__
>>   #define __ARM_PERF_EVENT_H__

>> -#ifdef CONFIG_PERF_EVENTS
>> -struct pt_regs;
>> -extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
>> -extern unsigned long perf_misc_flags(struct pt_regs *regs);
>> -#define perf_misc_flags(regs)	perf_misc_flags(regs)
>> -#endif
>> -
>>   #define perf_arch_fetch_caller_regs(regs, __ip) { \
>>   	(regs)->ARM_pc = (__ip); \
>>   	frame_pointer((regs)) = (unsigned long) __builtin_frame_address(0); \
>> diff --git a/arch/arm/kernel/perf_callchain.c  
>> b/arch/arm/kernel/perf_callchain.c
>> index 1d230ac9d0eb..a2601b1ef318 100644
>> --- a/arch/arm/kernel/perf_callchain.c
>> +++ b/arch/arm/kernel/perf_callchain.c
>> @@ -96,20 +96,3 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx  
>> *entry, struct pt_regs *re
>>   	arm_get_current_stackframe(regs, &fr);
>>   	walk_stackframe(&fr, callchain_trace, entry);
>>   }
>> -
>> -unsigned long perf_instruction_pointer(struct pt_regs *regs)
>> -{
>> -	return instruction_pointer(regs);
>> -}
>> -
>> -unsigned long perf_misc_flags(struct pt_regs *regs)
>> -{
>> -	int misc = 0;
>> -
>> -	if (user_mode(regs))
>> -		misc |= PERF_RECORD_MISC_USER;
>> -	else
>> -		misc |= PERF_RECORD_MISC_KERNEL;
>> -
>> -	return misc;
>> -}
>> --
>> 2.46.0.469.g59c65b2a67-goog