FAILED: patch "[PATCH] Kbuild: do not emit debug info for assembly with LLVM_IAS=1" failed to apply to 5.4-stable tree

FAILED: patch "[PATCH] Kbuild: do not emit debug info for assembly with LLVM_IAS=1" failed to apply to 5.4-stable tree

[gregkh]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b8a9092330da2030496ff357272f342eb970d51b Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Mon, 9 Nov 2020 10:35:28 -0800
Subject: [PATCH] Kbuild: do not emit debug info for assembly with LLVM_IAS=1

Clang's integrated assembler produces the warning for assembly files:

warning: DWARF2 only supports one section per compilation unit

If -Wa,-gdwarf-* is unspecified, then debug info is not emitted for
assembly sources (it is still emitted for C sources).  This will be
re-enabled for newer DWARF versions in a follow up patch.

Enables defconfig+CONFIG_DEBUG_INFO to build cleanly with
LLVM=1 LLVM_IAS=1 for x86_64 and arm64.

Cc: <stable@vger.kernel.org>
Link: https://github.com/ClangBuiltLinux/linux/issues/716
Reported-by: Dmitry Golovin <dima@golovin.in>
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Suggested-by: Dmitry Golovin <dima@golovin.in>
Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
Suggested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Fangrui Song <maskray@google.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

diff --git a/Makefile b/Makefile
index 87d659d3c8de..ae1592c1f5d6 100644
--- a/Makefile
+++ b/Makefile
@@ -828,7 +828,9 @@ else
 DEBUG_CFLAGS	+= -g
 endif
 
+ifneq ($(LLVM_IAS),1)
 KBUILD_AFLAGS	+= -Wa,-gdwarf-2
+endif
 
 ifdef CONFIG_DEBUG_INFO_DWARF4
 DEBUG_CFLAGS	+= -gdwarf-4

Re: FAILED: patch "[PATCH] Kbuild: do not emit debug info for assembly with LLVM_IAS=1" failed to apply to 5.4-stable tree

[Nick Desaulniers]

On Wed, Dec 9, 2020 at 1:03 AM <gregkh@linuxfoundation.org> wrote:
>
>
> The patch below does not apply to the 5.4-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

Cross referencing the thread where manual backports were provided:
https://lore.kernel.org/stable/CAKwvOdnGDHn+Y+g5AsKvOFiuF7iVAJ8+x53SgWxH9ejqEZwY9w@mail.gmail.com/
Sorry for the noise.

>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From b8a9092330da2030496ff357272f342eb970d51b Mon Sep 17 00:00:00 2001
> From: Nick Desaulniers <ndesaulniers@google.com>
> Date: Mon, 9 Nov 2020 10:35:28 -0800
> Subject: [PATCH] Kbuild: do not emit debug info for assembly with LLVM_IAS=1
>
> Clang's integrated assembler produces the warning for assembly files:
>
> warning: DWARF2 only supports one section per compilation unit
>
> If -Wa,-gdwarf-* is unspecified, then debug info is not emitted for
> assembly sources (it is still emitted for C sources).  This will be
> re-enabled for newer DWARF versions in a follow up patch.
>
> Enables defconfig+CONFIG_DEBUG_INFO to build cleanly with
> LLVM=1 LLVM_IAS=1 for x86_64 and arm64.
>
> Cc: <stable@vger.kernel.org>
> Link: https://github.com/ClangBuiltLinux/linux/issues/716
> Reported-by: Dmitry Golovin <dima@golovin.in>
> Reported-by: Nathan Chancellor <natechancellor@gmail.com>
> Suggested-by: Dmitry Golovin <dima@golovin.in>
> Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
> Suggested-by: Sedat Dilek <sedat.dilek@gmail.com>
> Reviewed-by: Fangrui Song <maskray@google.com>
> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
>
> diff --git a/Makefile b/Makefile
> index 87d659d3c8de..ae1592c1f5d6 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -828,7 +828,9 @@ else
>  DEBUG_CFLAGS   += -g
>  endif
>
> +ifneq ($(LLVM_IAS),1)
>  KBUILD_AFLAGS  += -Wa,-gdwarf-2
> +endif
>
>  ifdef CONFIG_DEBUG_INFO_DWARF4
>  DEBUG_CFLAGS   += -gdwarf-4
>


-- 
Thanks,
~Nick Desaulniers