linux-kernel - Re: [PATCH v3] purgatory: fix disabling debug info

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Date:   Thu, 30 Mar 2023 15:29:28 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Alyssa Ross <hi@...ssa.is>
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        Nick Cao <nickcao@...hi.co>, linux-kbuild@...r.kernel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        linux-riscv@...ts.infradead.org, Tom Rix <trix@...hat.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        stable@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v3] purgatory: fix disabling debug info

On Thu, Mar 30, 2023 at 06:22:24PM +0000, Alyssa Ross wrote:
> Since 32ef9e5054ec, -Wa,-gdwarf-2 is no longer used in KBUILD_AFLAGS.
> Instead, it includes -g, the appropriate -gdwarf-* flag, and also the
> -Wa versions of both of those if building with Clang and GNU as.  As a
> result, debug info was being generated for the purgatory objects, even
> though the intention was that it not be.
> 
> Fixes: 32ef9e5054ec ("Makefile.debug: re-enable debug info for .S files")
> Signed-off-by: Alyssa Ross <hi@...ssa.is>
> Cc: stable@...r.kernel.org
> Acked-by: Nick Desaulniers <ndesaulniers@...gle.com>

This is definitely more future proof.

Reviewed-by: Nathan Chancellor <nathan@...nel.org>
Tested-by: Nathan Chancellor <nathan@...nel.org>

> ---
> v2: https://lore.kernel.org/r/20230326182120.194541-1-hi@alyssa.is
> 
> Difference from v2: replaced asflags-remove-y with every possible
> debug flag with asflags-y += -g0, as suggested by Nick Desaulniers.
> 
> Additionally, I've CCed the x86 maintainers this time, since Masahiro
> said he would like acks from subsystem maintainers, and
> get_maintainer.pl didn't pick them the first time around.
> 
>  arch/riscv/purgatory/Makefile | 7 +------
>  arch/x86/purgatory/Makefile   | 3 +--
>  2 files changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile
> index d16bf715a586..9c1e71853ee7 100644
> --- a/arch/riscv/purgatory/Makefile
> +++ b/arch/riscv/purgatory/Makefile
> @@ -84,12 +84,7 @@ CFLAGS_string.o			+= $(PURGATORY_CFLAGS)
>  CFLAGS_REMOVE_ctype.o		+= $(PURGATORY_CFLAGS_REMOVE)
>  CFLAGS_ctype.o			+= $(PURGATORY_CFLAGS)
>  
> -AFLAGS_REMOVE_entry.o		+= -Wa,-gdwarf-2
> -AFLAGS_REMOVE_memcpy.o		+= -Wa,-gdwarf-2
> -AFLAGS_REMOVE_memset.o		+= -Wa,-gdwarf-2
> -AFLAGS_REMOVE_strcmp.o		+= -Wa,-gdwarf-2
> -AFLAGS_REMOVE_strlen.o		+= -Wa,-gdwarf-2
> -AFLAGS_REMOVE_strncmp.o		+= -Wa,-gdwarf-2
> +asflags-y			+= -g0
>  
>  $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
>  		$(call if_changed,ld)
> diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
> index 17f09dc26381..8e6c81b1c8f7 100644
> --- a/arch/x86/purgatory/Makefile
> +++ b/arch/x86/purgatory/Makefile
> @@ -69,8 +69,7 @@ CFLAGS_sha256.o			+= $(PURGATORY_CFLAGS)
>  CFLAGS_REMOVE_string.o		+= $(PURGATORY_CFLAGS_REMOVE)
>  CFLAGS_string.o			+= $(PURGATORY_CFLAGS)
>  
> -AFLAGS_REMOVE_setup-x86_$(BITS).o	+= -Wa,-gdwarf-2
> -AFLAGS_REMOVE_entry64.o			+= -Wa,-gdwarf-2
> +asflags-y			+= -g0
>  
>  $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
>  		$(call if_changed,ld)
> -- 
> 2.37.1
> 
>