x86/*/Makefile: Use -fno-asynchronous-unwind-tables to suppress .eh_frame sections

While discussing a patch to discard .eh_frame from the compressed
vmlinux using the linker script, Fangrui Song pointed out [1] that these
sections shouldn't exist in the first place because arch/x86/Makefile
uses -fno-asynchronous-unwind-tables.

It turns out this is because the Makefiles used to build the compressed
kernel redefine KBUILD_CFLAGS, dropping this flag.

Add the flag to the Makefile for the compressed kernel, as well as the
EFI stub Makefile to fix this.

Also add the flag to boot/Makefile and realmode/rm/Makefile so that the
kernel's boot code (boot/setup.elf) and realmode trampoline
(realmode/rm/realmode.elf) won't be compiled with .eh_frame sections,
since their linker scripts also just discard them.

  [1] https://lore.kernel.org/lkml/[email protected]/

Suggested-by: Fangrui Song <[email protected]>
Signed-off-by: Arvind Sankar <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Nathan Chancellor <[email protected]>
Reviewed-by: Nick Desaulniers <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Tested-by: Nathan Chancellor <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

0 files changed, 0 insertions, 0 deletions