Messages in this thread Patch in this message | | | Date | Wed, 25 Mar 2020 16:12:49 -0700 | Subject | [PATCH] elfnote: mark all .note sections SHF_ALLOC | From | Nick Desaulniers <> |
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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
Link: https://github.com/ClangBuiltLinux/linux/issues/913 Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Debugged-by: Ilie Halip <ilie.halip@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> --- Ilie has further treewide cleanups: https://github.com/ihalip/linux/commits/elfnote This patch is the simplest to move us forwards.
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 594d4e78654f..69b136e4dd2b 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 -- 2.26.0.rc2.310.g2932bb562d-goog
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