On Fri, Jan 29, 2021 at 05:46:51PM -0700, Nathan Chancellor wrote:
> 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 <[email protected]>
> Reviewed-by: Fangrui Song <[email protected]>
> Reviewed-by: Nick Desaulniers <[email protected]>
> Signed-off-by: Nathan Chancellor <[email protected]>
> ---
>
> v2 -> v3:
>
> * Fix double "unwanted" in comment section per Sedat.
>
> v1 -> v2:
>
> * Keep configs and flag names alphabetized.
>
> * Drop mention of -ftest-coverage since it does not cause this issue per
> Fangrui.
>
> * Pick up review tags from Fangrui and Nick.
>
> include/asm-generic/vmlinux.lds.h | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/include/asm-generic/vmlinux.lds.h
> b/include/asm-generic/vmlinux.lds.h
> index b2b3d81b1535..b61b537177fb 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
> - * unwanted sections (.eh_frame and .init_array.*), but
> - * CONFIG_CONSTRUCTORS wants to keep any .init_array.* sections.
> + * Clang's -fprofile-arcs, -fsanitize=kernel-address, and
> + * -fsanitize=thread produce 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_GCOV_KERNEL) || defined(CONFIG_KASAN_GENERIC) ||
> defined(CONFIG_KCSAN)
> # ifdef CONFIG_CONSTRUCTORS
> # define SANITIZER_DISCARDS \
> *(.eh_frame)
>
> base-commit: bec4c2968fce2f44ce62d05288a633cd99a722eb
> --
> 2.30.0
>
Andrew, Arnd, or Kees:
Would one of you be able to pick this up and get it to Linus? I think
the 0day bot just tripped over this again:
https://lists.01.org/hyperkitty/list/[email protected]/message/BXBY7OPVMOCCUZSCFEZXI7RG65RJWJ52/
https://lists.01.org/hyperkitty/list/[email protected]/message/QF62LWM6YSNWWNOM7AXYK4734AKH2SVT/
Cheers,
Nathan
