From b4aa6da26135ab84dc00b9359879115baad730dd Mon Sep 17 00:00:00 2001 From: Nick Desaulniers Date: Thu, 4 Jun 2020 16:50:49 -0700 Subject: [PATCH] elfnote: mark all .note sections SHF_ALLOC commit 51da9dfb7f20911ae4e79e9b412a9c2d4c373d4b upstream. 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 Signed-off-by: Andrew Morton Reviewed-by: Nathan Chancellor Reviewed-by: Fangrui Song Cc: Jeremy Fitzhardinge Cc: Thomas Gleixner Cc: Vincenzo Frascino Link: https://github.com/ClangBuiltLinux/linux/issues/913 Link: http://lkml.kernel.org/r/20200325231250.99205-1-ndesaulniers@google.com Debugged-by: Ilie Halip Signed-off-by: Linus Torvalds Cc: Jian Cai Signed-off-by: Greg Kroah-Hartman --- 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