From: Nick Desaulniers <ndesaulniers@google.com>
Date: Mon, 9 Nov 2020 18:35:28 +0000 (-0800)
Subject: Kbuild: do not emit debug info for assembly with LLVM_IAS=1
X-Git-Tag: v5.9.15~105
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1fcaa002e3ca7137379c96f63452612bdb5a1e88;p=thirdparty%2Fkernel%2Fstable.git

Kbuild: do not emit debug info for assembly with LLVM_IAS=1

commit b8a9092330da2030496ff357272f342eb970d51b upstream.

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>
[nd: backport to avoid conflicts from:
  commit 695afd3d7d58 ("kbuild: Simplify DEBUG_INFO Kconfig handling")]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/Makefile b/Makefile
index 0983973bcf082..a5dbc06c020f7 100644
--- a/Makefile
+++ b/Makefile
@@ -821,8 +821,11 @@ DEBUG_CFLAGS	+= -gsplit-dwarf
 else
 DEBUG_CFLAGS	+= -g
 endif
+ifneq ($(LLVM_IAS),1)
 KBUILD_AFLAGS	+= -Wa,-gdwarf-2
 endif
+endif
+
 ifdef CONFIG_DEBUG_INFO_DWARF4
 DEBUG_CFLAGS	+= -gdwarf-4
 endif