diff options
| author | Kees Cook <keescook@chromium.org> | 2020-08-21 12:42:48 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-09-01 09:50:36 +0200 |
| commit | e2179a09ab089d3423751bd2b0c884ddb3eabe84 (patch) | |
| tree | 3ac95308f4a4342455582474f6702d20216c9415 /drivers/firmware | |
| parent | eff8728fe69880d3f7983bec3fb6cea4c306261f (diff) | |
| download | linux-e2179a09ab089d3423751bd2b0c884ddb3eabe84.tar.bz2 | |
efi/libstub: Disable -mbranch-protection
In preparation for adding --orphan-handling=warn to more architectures,
disable -mbranch-protection, as EFI does not yet support it[1]. This was
noticed due to it producing unwanted .note.gnu.property sections (prefixed
with .init due to the objcopy build step).
However, we must also work around a bug in Clang where the section is
still emitted for code-less object files[2], so also remove the section
during the objcopy.
[1] https://lore.kernel.org/lkml/CAMj1kXHck12juGi=E=P4hWP_8vQhQ+-x3vBMc3TGeRWdQ-XkxQ@mail.gmail.com
[2] https://bugs.llvm.org/show_bug.cgi?id=46480
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20200821194310.3089815-8-keescook@chromium.org
Diffstat (limited to 'drivers/firmware')
| -rw-r--r-- | drivers/firmware/efi/libstub/Makefile | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index 5eefd60917df..0c911e391d75 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -18,7 +18,8 @@ cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ \ # arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly # disable the stackleak plugin cflags-$(CONFIG_ARM64) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ - -fpie $(DISABLE_STACKLEAK_PLUGIN) + -fpie $(DISABLE_STACKLEAK_PLUGIN) \ + $(call cc-option,-mbranch-protection=none) cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ -fno-builtin -fpic \ $(call cc-option,-mno-single-pic-base) @@ -66,6 +67,12 @@ lib-$(CONFIG_X86) += x86-stub.o CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) +# Even when -mbranch-protection=none is set, Clang will generate a +# .note.gnu.property for code-less object files (like lib/ctype.c), +# so work around this by explicitly removing the unwanted section. +# https://bugs.llvm.org/show_bug.cgi?id=46480 +STUBCOPY_FLAGS-y += --remove-section=.note.gnu.property + # # For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the # .bss section, so the .bss section of the EFI stub needs to be included in the |