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

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Message-ID: <ZtmHBuggqUr3ncw6@J2N7QTR9R3>
Date: Thu, 5 Sep 2024 11:25:10 +0100
From: Mark Rutland <mark.rutland@....com>
To: Colton Lewis <coltonlewis@...gle.com>
Cc: kvm@...r.kernel.org, Oliver Upton <oliver.upton@...ux.dev>,
	Sean Christopherson <seanjc@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Will Deacon <will@...nel.org>, Russell King <linux@...linux.org.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Naveen N Rao <naveen@...nel.org>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	"H . Peter Anvin" <hpa@...or.com>, linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org
Subject: Re: [PATCH 1/5] arm: perf: Drop unused functions

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@....com>

Mark.

> 
> Signed-off-by: Colton Lewis <coltonlewis@...gle.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
>