Commit 51da9dfb authored by Nick Desaulniers's avatar Nick Desaulniers Committed by Linus Torvalds

elfnote: mark all .note sections SHF_ALLOC

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: default avatarNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarNathan Chancellor <natechancellor@gmail.com>
Reviewed-by: default avatarFangrui 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.comDebugged-by: default avatarIlie Halip <ilie.halip@gmail.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 852991dd
...@@ -54,7 +54,7 @@ ...@@ -54,7 +54,7 @@
.popsection ; .popsection ;
#define ELFNOTE(name, type, desc) \ #define ELFNOTE(name, type, desc) \
ELFNOTE_START(name, type, "") \ ELFNOTE_START(name, type, "a") \
desc ; \ desc ; \
ELFNOTE_END ELFNOTE_END
......
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