From: David Gow <davidgow@google.com>
To: Kees Cook <keescook@chromium.org>
Cc: David Gow <davidgow@google.com>, Jeff Dike <jdike@addtoit.com>,
Richard Weinberger <richard@nod.at>,
Anton Ivanov <anton.ivanov@cambridgegreys.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Nathan Chancellor <nathan@kernel.org>,
linux-um@lists.infradead.org, linux-kbuild@vger.kernel.org,
linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
llvm@lists.linux.dev, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: [PATCH] um: clang: Strip out -mno-global-merge from USER_CFLAGS
Date: Thu, 3 Mar 2022 17:06:42 +0800 [thread overview]
Message-ID: <20220303090643.241747-1-davidgow@google.com> (raw)
The things built with USER_CFLAGS don't seem to recognise it as a
compiler option, and print a warning:
clang: warning: argument unused during compilation: '-mno-global-merge' [-Wunused-command-line-argument]
Fixes: 744814d2fa ("um: Allow builds with Clang")
Signed-off-by: David Gow <davidgow@google.com>
---
This warning shows up after merging:
https://lore.kernel.org/lkml/20220227184517.504931-6-keescook@chromium.org/
I'm not 100% sure why this is necessary, but it does seem to work. All
the attempts to get rid of -mno-global-merge entirely have been met with
skepticism, but I'm guessing that it's not a problem for just the UML
"user" files, as they shouldn't(?) interact too much with modules.
arch/um/Makefile | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/um/Makefile b/arch/um/Makefile
index f2fe63bfd819..320b09cd513c 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -75,6 +75,10 @@ USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -I%,,$(KBUILD_CFLAGS))) \
-D_FILE_OFFSET_BITS=64 -idirafter $(srctree)/include \
-idirafter $(objtree)/include -D__KERNEL__ -D__UM_HOST__
+ifdef CONFIG_CC_IS_CLANG
+USER_CFLAGS := $(patsubst -mno-global-merge,,$(USER_CFLAGS))
+endif
+
#This will adjust *FLAGS accordingly to the platform.
include $(srctree)/$(ARCH_DIR)/Makefile-os-$(OS)
--
2.35.1.616.g0bdcbb4464-goog
next reply other threads:[~2022-03-03 9:06 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-03 9:06 David Gow [this message]
2022-03-03 17:30 ` [PATCH] um: clang: Strip out -mno-global-merge from USER_CFLAGS Nathan Chancellor
2022-03-03 18:04 ` Kees Cook
2022-03-03 18:26 ` Nathan Chancellor
2022-03-03 18:39 ` Nick Desaulniers
2022-03-04 11:42 ` Sedat Dilek
2022-03-04 6:51 ` David Gow
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