From ed647c9c7aa3f94beab8ea0cbb1419df05130adf Mon Sep 17 00:00:00 2001 From: Nick Desaulniers Date: Thu, 30 Apr 2020 16:17:43 +1000 Subject: [PATCH] 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 Link: https://github.com/ClangBuiltLinux/linux/issues/913 Link: http://lkml.kernel.org/r/20200325231250.99205-1-ndesaulniers@google.com Signed-off-by: Nick Desaulniers Debugged-by: Ilie Halip Reviewed-by: Nathan Chancellor Reviewed-by: Fangrui Song Cc: Jeremy Fitzhardinge Cc: Thomas Gleixner Cc: Vincenzo Frascino Signed-off-by: Andrew Morton Signed-off-by: Stephen Rothwell --- 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 594d4e78654fcf..69b136e4dd2b6f 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