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From: Nathan Chancellor <nathan@kernel.org>
To: Arnd Bergmann <arnd@arndb.de>, Kees Cook <keescook@chromium.org>,
	Nick Desaulniers <ndesaulniers@google.com>
Cc: linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
	Nathan Chancellor <nathan@kernel.org>,
	kernel test robot <lkp@intel.com>
Subject: [PATCH] vmlinux.lds.h: Define SANTIZER_DISCARDS with CONFIG_GCOV_KERNEL=y
Date: Fri, 29 Jan 2021 13:11:16 -0700	[thread overview]
Message-ID: <20210129201116.2658179-1-nathan@kernel.org> (raw)

clang produces .eh_frame sections when CONFIG_GCOV_KERNEL is enabled,
even when -fno-asynchronous-unwind-tables is in KBUILD_CFLAGS:

$ make CC=clang vmlinux
...
ld: warning: orphan section `.eh_frame' from `init/main.o' being placed in section `.eh_frame'
ld: warning: orphan section `.eh_frame' from `init/version.o' being placed in section `.eh_frame'
ld: warning: orphan section `.eh_frame' from `init/do_mounts.o' being placed in section `.eh_frame'
ld: warning: orphan section `.eh_frame' from `init/do_mounts_initrd.o' being placed in section `.eh_frame'
ld: warning: orphan section `.eh_frame' from `init/initramfs.o' being placed in section `.eh_frame'
ld: warning: orphan section `.eh_frame' from `init/calibrate.o' being placed in section `.eh_frame'
ld: warning: orphan section `.eh_frame' from `init/init_task.o' being placed in section `.eh_frame'
...

$ rg "GCOV_KERNEL|GCOV_PROFILE_ALL" .config
CONFIG_GCOV_KERNEL=y
CONFIG_ARCH_HAS_GCOV_PROFILE_ALL=y
CONFIG_GCOV_PROFILE_ALL=y

This was already handled for a couple of other options in
commit d812db78288d ("vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted
sections") and there is an open LLVM bug for this issue. Take advantage
of that section for this config as well so that there are no more orphan
warnings.

Link: https://bugs.llvm.org/show_bug.cgi?id=46478
Link: https://github.com/ClangBuiltLinux/linux/issues/1069
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 include/asm-generic/vmlinux.lds.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index b2b3d81b1535..f753fd449436 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -988,12 +988,13 @@
 #endif
 
 /*
- * Clang's -fsanitize=kernel-address and -fsanitize=thread produce
+ * Clang's -fsanitize=kernel-address, -fsanitize=thread,
+ * and -fprofile-arcs -ftest-coverage produce unwanted
  * unwanted sections (.eh_frame and .init_array.*), but
  * CONFIG_CONSTRUCTORS wants to keep any .init_array.* sections.
  * https://bugs.llvm.org/show_bug.cgi?id=46478
  */
-#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KCSAN)
+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KCSAN) || defined(CONFIG_GCOV_KERNEL)
 # ifdef CONFIG_CONSTRUCTORS
 #  define SANITIZER_DISCARDS						\
 	*(.eh_frame)

base-commit: bec4c2968fce2f44ce62d05288a633cd99a722eb
-- 
2.30.0


             reply	other threads:[~2021-01-29 20:13 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-29 20:11 Nathan Chancellor [this message]
2021-01-29 20:18 ` Nick Desaulniers
2021-01-29 21:27   ` Fangrui Song
2021-01-30  0:25 ` [PATCH v2] " Nathan Chancellor
2021-01-30  0:39   ` Sedat Dilek
2021-01-30  0:46   ` [PATCH v3] " Nathan Chancellor
2021-02-25 19:28     ` Nathan Chancellor
2021-02-25 21:19     ` Kees Cook

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