[PATCH 13/15] x86, cpu: Use LTO for cpu.c with CFI

From: Sami Tolvanen
Date: Fri Apr 16 2021 - 16:39:40 EST


Allow LTO to be used for cpu.c when CONFIG_CFI_CLANG is enabled to avoid
indirect call failures. CFI requires Clang >= 12, which doesn't have the
stack protector inlining bug.

Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
---
arch/x86/power/Makefile | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/x86/power/Makefile b/arch/x86/power/Makefile
index 379777572bc9..a0532851fed7 100644
--- a/arch/x86/power/Makefile
+++ b/arch/x86/power/Makefile
@@ -4,9 +4,11 @@
# itself be stack-protected
CFLAGS_cpu.o := -fno-stack-protector

+ifndef CONFIG_CFI_CLANG
# Clang may incorrectly inline functions with stack protector enabled into
# __restore_processor_state(): https://bugs.llvm.org/show_bug.cgi?id=47479
CFLAGS_REMOVE_cpu.o := $(CC_FLAGS_LTO)
+endif

obj-$(CONFIG_PM_SLEEP) += cpu.o
obj-$(CONFIG_HIBERNATION) += hibernate_$(BITS).o hibernate_asm_$(BITS).o hibernate.o
--
2.31.1.368.gbe11c130af-goog