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    Subject[PATCH AUTOSEL 4.14 099/108] elfnote: mark all .note sections SHF_ALLOC
    Date
    From: Nick Desaulniers <ndesaulniers@google.com>

    [ Upstream commit 51da9dfb7f20911ae4e79e9b412a9c2d4c373d4b ]

    ELFNOTE_START allows callers to specify flags for .pushsection assembler
    directives. All callsites but ELF_NOTE use "a" for SHF_ALLOC. For vdso's
    that explicitly use ELF_NOTE_START and BUILD_SALT, the same section is
    specified twice after preprocessing, once with "a" flag, once without.
    Example:

    .pushsection .note.Linux, "a", @note ;
    .pushsection .note.Linux, "", @note ;

    While GNU as allows this ordering, it warns for the opposite ordering,
    making these directives position dependent. We'd prefer not to precisely
    match this behavior in Clang's integrated assembler. Instead, the non
    __ASSEMBLY__ definition of ELF_NOTE uses
    __attribute__((section(".note.Linux"))) which is created with SHF_ALLOC,
    so let's make the __ASSEMBLY__ definition of ELF_NOTE consistent with C
    and just always use "a" flag.

    This allows Clang to assemble a working mainline (5.6) kernel via:
    $ make CC=clang AS=clang

    Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
    Reviewed-by: Fangrui Song <maskray@google.com>
    Cc: Jeremy Fitzhardinge <jeremy@goop.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
    Link: https://github.com/ClangBuiltLinux/linux/issues/913
    Link: http://lkml.kernel.org/r/20200325231250.99205-1-ndesaulniers@google.com
    Debugged-by: Ilie Halip <ilie.halip@gmail.com>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    include/linux/elfnote.h | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/include/linux/elfnote.h b/include/linux/elfnote.h
    index f236f5b931b2..7fdd7f355b52 100644
    --- a/include/linux/elfnote.h
    +++ b/include/linux/elfnote.h
    @@ -54,7 +54,7 @@
    .popsection ;

    #define ELFNOTE(name, type, desc) \
    - ELFNOTE_START(name, type, "") \
    + ELFNOTE_START(name, type, "a") \
    desc ; \
    ELFNOTE_END

    --
    2.25.1
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