Messages in this thread | | | From | Nick Desaulniers <> | Date | Fri, 3 Apr 2020 15:13:34 -0700 | Subject | Re: [PATCH] elfnote: mark all .note sections SHF_ALLOC |
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dropping Jeremy; I got bounceback from the email address. Ping for review?
On Wed, Mar 25, 2020 at 4:13 PM Nick Desaulniers <ndesaulniers@google.com> wrote: > > 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 >
-- Thanks, ~Nick Desaulniers
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