From: Nathan Chancellor <natechancellor@gmail.com>
To: Masahiro Yamada <yamada.masahiro@socionext.com>,
Michal Marek <michal.lkml@markovi.net>,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Nick Desaulniers <ndesaulniers@google.com>,
Arnd Bergmann <arnd@arndb.de>,
James Y Knight <jyknight@google.com>,
clang-built-linux@googlegroups.com,
Nathan Chancellor <natechancellor@gmail.com>,
stable@vger.kernel.org
Subject: [PATCH] Makefile: Add '-fno-builtin-bcmp' to CLANG_FLAGS
Date: Tue, 12 Mar 2019 14:52:04 -0700 [thread overview]
Message-ID: <20190312215203.27643-1-natechancellor@gmail.com> (raw)
After LLVM revision r355672 [1], all known working kernel configurations
fail to link [2]:
ld: init/do_mounts.o: in function `prepare_namespace':
do_mounts.c:(.init.text+0x5ca): undefined reference to `bcmp'
ld: do_mounts.c:(.init.text+0x5e6): undefined reference to `bcmp'
ld: init/initramfs.o: in function `do_header':
initramfs.c:(.init.text+0x6e0): undefined reference to `bcmp'
ld: initramfs.c:(.init.text+0x6f8): undefined reference to `bcmp'
ld: arch/x86/kernel/setup.o: in function `setup_arch':
setup.c:(.init.text+0x21d): undefined reference to `bcmp'
Commit 6edfba1b33c7 ("[PATCH] x86_64: Don't define string functions to
builtin") removed '-ffreestanding' globally and the kernel doesn't
provide a bcmp definition so the linker cannot find a reference to it.
Fix this by explicitly telling LLVM through Clang not to emit bcmp
references. This flag does not need to be behind 'cc-option' because all
working versions of Clang support this flag.
[1]: https://github.com/llvm/llvm-project/commit/8e16d73346f8091461319a7dfc4ddd18eedcff13
[2]: https://travis-ci.com/ClangBuiltLinux/continuous-integration/builds/104027249
Link: https://github.com/ClangBuiltLinux/linux/issues/416
Link: https://bugs.llvm.org/show_bug.cgi?id=41035
Cc: stable@vger.kernel.org
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
Makefile | 1 +
1 file changed, 1 insertion(+)
diff --git a/Makefile b/Makefile
index 9ef547fc7ffe..6645a274b6e3 100644
--- a/Makefile
+++ b/Makefile
@@ -501,6 +501,7 @@ ifneq ($(GCC_TOOLCHAIN),)
CLANG_FLAGS += --gcc-toolchain=$(GCC_TOOLCHAIN)
endif
CLANG_FLAGS += -no-integrated-as
+CLANG_FLAGS += -fno-builtin-bcmp
KBUILD_CFLAGS += $(CLANG_FLAGS)
KBUILD_AFLAGS += $(CLANG_FLAGS)
export CLANG_FLAGS
--
2.21.0
next reply other threads:[~2019-03-12 21:53 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-12 21:52 Nathan Chancellor [this message]
2019-03-12 22:55 ` [PATCH] Makefile: Add '-fno-builtin-bcmp' to CLANG_FLAGS Nick Desaulniers
2019-03-13 8:13 ` Rasmus Villemoes
2019-03-13 10:58 ` Masahiro Yamada
2019-03-13 13:44 ` Nathan Chancellor
2019-03-13 13:48 ` Arnd Bergmann
2019-03-13 15:32 ` Nathan Chancellor
2019-03-13 17:21 ` Nick Desaulniers
2019-03-13 17:27 ` Nick Desaulniers
2019-03-13 18:02 ` [PATCH] lib/string.c: implement a basic bcmp Nick Desaulniers
2019-03-13 18:11 ` Nick Desaulniers
2019-03-13 18:17 ` [PATCH v2] " Nick Desaulniers
2019-03-13 18:40 ` Steven Rostedt
2019-03-13 18:51 ` Nick Desaulniers
2019-03-13 19:01 ` Steven Rostedt
2019-03-13 19:34 ` Rasmus Villemoes
2019-03-13 20:12 ` Steven Rostedt
2019-03-13 20:37 ` [PATCH v3] " Nick Desaulniers
2019-03-13 21:03 ` Steven Rostedt
2019-03-13 21:13 ` [PATCH v4] " Nick Desaulniers
2019-03-14 3:15 ` Nathan Chancellor
2019-03-14 5:00 ` Masahiro Yamada
2019-03-14 8:33 ` Andy Shevchenko
2019-03-14 9:57 ` David Laight
2019-03-14 11:07 ` Rasmus Villemoes
2019-03-21 2:11 ` Andrew Morton
2019-03-21 17:02 ` Nick Desaulniers
2019-03-21 17:20 ` Nick Desaulniers
2019-03-21 21:05 ` Andrew Morton
2019-03-22 7:17 ` Rasmus Villemoes
2019-03-22 7:43 ` Sedat Dilek
2019-03-13 19:38 ` [PATCH] Makefile: Add '-fno-builtin-bcmp' to CLANG_FLAGS Arnd Bergmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190312215203.27643-1-natechancellor@gmail.com \
--to=natechancellor@gmail.com \
--cc=arnd@arndb.de \
--cc=clang-built-linux@googlegroups.com \
--cc=jyknight@google.com \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=michal.lkml@markovi.net \
--cc=ndesaulniers@google.com \
--cc=stable@vger.kernel.org \
--cc=yamada.masahiro@socionext.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).