Messages in this thread | | | Date | Tue, 23 Jun 2020 20:31:42 -0700 | From | Fangrui Song <> | Subject | Re: [PATCH v3 3/9] efi/libstub: Remove .note.gnu.property |
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On 2020-06-23, Kees Cook wrote: >In preparation for adding --orphan-handling=warn to more architectures, >make sure unwanted sections don't end up appearing under the .init >section prefix that libstub adds to itself during objcopy. > >Signed-off-by: Kees Cook <keescook@chromium.org> >--- > drivers/firmware/efi/libstub/Makefile | 3 +++ > 1 file changed, 3 insertions(+) > >diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile >index 75daaf20374e..9d2d2e784bca 100644 >--- a/drivers/firmware/efi/libstub/Makefile >+++ b/drivers/firmware/efi/libstub/Makefile >@@ -66,6 +66,9 @@ lib-$(CONFIG_X86) += x86-stub.o > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > >+# Remove unwanted sections first. >+STUBCOPY_FLAGS-y += --remove-section=.note.gnu.property >+ > # > # For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the > # .bss section, so the .bss section of the EFI stub needs to be included in the
arch/arm64/Kconfig enables ARM64_PTR_AUTH by default. When the config is on
ifeq ($(CONFIG_ARM64_BTI_KERNEL),y) branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET_BTI) := -mbranch-protection=pac-ret+leaf+bti else branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET) := -mbranch-protection=pac-ret+leaf endif
This option creates .note.gnu.property:
% readelf -n drivers/firmware/efi/libstub/efi-stub.o
Displaying notes found in: .note.gnu.property Owner Data size Description GNU 0x00000010 NT_GNU_PROPERTY_TYPE_0 Properties: AArch64 feature: PAC
If .note.gnu.property is not desired in drivers/firmware/efi/libstub, specifying -mbranch-protection=none can override -mbranch-protection=pac-ret+leaf
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