Messages in this thread | | | Date | Mon, 29 Jun 2020 09:06:07 -0700 | From | Kees Cook <> | Subject | Re: [PATCH v3 6/7] x86/boot: Remove runtime relocations from head_{32,64}.S |
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On Mon, Jun 29, 2020 at 10:09:27AM -0400, Arvind Sankar wrote: > The BFD linker generates runtime relocations for z_input_len and > z_output_len, even though they are absolute symbols. > > This is fixed for binutils-2.35 [1]. Work around this for earlier > versions by defining two variables input_len and output_len in addition > to the symbols, and use them via position-independent references. > > This eliminates the last two runtime relocations in the head code and > allows us to drop the -z noreloc-overflow flag to the linker. > > [1] https://sourceware.org/bugzilla/show_bug.cgi?id=25754 > > Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> > Reviewed-by: Ard Biesheuvel <ardb@kernel.org> > Reviewed-by: Fangrui Song <maskray@google.com> > --- > arch/x86/boot/compressed/Makefile | 8 -------- > arch/x86/boot/compressed/head_32.S | 17 ++++++++--------- > arch/x86/boot/compressed/head_64.S | 4 ++-- > arch/x86/boot/compressed/mkpiggy.c | 6 ++++++ > 4 files changed, 16 insertions(+), 19 deletions(-)
I continue to really enjoy the smaller code. Anything that makes mkpiggy.c smaller is a win. :)
Reviewed-by: Kees Cook <keescook@chromium.org>
-- Kees Cook
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