From: Sami Tolvanen <samitolvanen@google.com>
Date: Mon, 27 Apr 2020 16:00:18 +0000 (-0700)
Subject: efi/libstub: Disable Shadow Call Stack
X-Git-Tag: v5.8-rc1~213^2^2~7
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=cc49c71d2abe99c1c2c9bedf0693ad2d3ee4a067;p=users%2Fwilly%2Flinux.git

efi/libstub: Disable Shadow Call Stack

Shadow stacks are not available in the EFI stub, filter out SCS flags.

Suggested-by: James Morse <james.morse@arm.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
---

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 094eabdecfe6..b52ae8c29560 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -32,6 +32,9 @@ KBUILD_CFLAGS			:= $(cflags-y) -DDISABLE_BRANCH_PROFILING \
 				   $(call cc-option,-fno-stack-protector) \
 				   -D__DISABLE_EXPORTS
 
+# remove SCS flags from all objects in this directory
+KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS))
+
 GCOV_PROFILE			:= n
 KASAN_SANITIZE			:= n
 UBSAN_SANITIZE			:= n