Subject: Re: [PATCH] riscv: Require FRAME_POINTER for some configurations

From: Conor Dooley <[email-masked]>
Date: Wed, 23 Aug 2023 16:44:24 +0100

On Wed, Aug 23, 2023 at 10:28:45AM +0200, Björn Töpel wrote:
> From: Björn Töpel <[email-masked]>
> 
> Some V configurations implicitly turn on '-fno-omit-frame-pointer',
> but leaving FRAME_POINTER disabled. This makes it hard to reason about
> the FRAME_POINTER config, and also triggers build failures introduced
> in by the commit in the Fixes: tag.
> 
> Select FRAME_POINTER explicitly for these configurations.
> 
> Fixes: ebc9cb03b21e ("riscv: stack: Fixup independent softirq stack for CONFIG_FRAME_POINTER=n")
> Signed-off-by: Björn Töpel <[email-masked]>

I think this is reasonable, even if you pre-patch version of this seemed
quite sceptical.
Reviewed-by: Conor Dooley <[email-masked]>

Thanks,
Conor.

> ---
>  arch/riscv/Kconfig  | 1 +
>  arch/riscv/Makefile | 3 ---
>  2 files changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 10e7a7ad175a..cd8075c092c3 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -62,6 +62,7 @@ config RISCV
>  	select COMMON_CLK
>  	select CPU_PM if CPU_IDLE || HIBERNATION
>  	select EDAC_SUPPORT
> +	select FRAME_POINTER if PERF_EVENTS || (FUNCTION_TRACER && !DYNAMIC_FTRACE)
>  	select GENERIC_ARCH_TOPOLOGY
>  	select GENERIC_ATOMIC64 if !64BIT
>  	select GENERIC_CLOCKEVENTS_BROADCAST if SMP
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index 6ec6d52a4180..1329e060c548 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -87,9 +87,6 @@ endif
>  ifeq ($(CONFIG_CMODEL_MEDANY),y)
>  	KBUILD_CFLAGS += -mcmodel=medany
>  endif
> -ifeq ($(CONFIG_PERF_EVENTS),y)
> -        KBUILD_CFLAGS += -fno-omit-frame-pointer
> -endif
>  
>  # Avoid generating .eh_frame sections.
>  KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables
> 
> base-commit: 89bf6209cad66214d3774dac86b6bbf2aec6a30d
> -- 
> 2.39.2
> 
> 
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