KBUILD_CFLAGS is very carefully built up in the top level Makefile, particularly when cross compiling or using different build tools. Resetting KBUILD_CFLAGS via := assignment is an antipattern.
The comment above the reset mentions that -pg is problematic. Other Makefiles use `CFLAGS_REMOVE_file.o = $(CC_FLAGS_FTRACE)` when CONFIG_FUNCTION_TRACER is set. Prefer that pattern to wiping out all of the important KBUILD_CFLAGS then manually having to re-add them. Seems also that __stack_chk_fail references are generated when using CONFIG_STACKPROTECTOR or CONFIG_STACKPROTECTOR_STRONG.
Cc: stable@vger.kernel.org Fixes: 8fc5b4d4121c ("purgatory: core purgatory functionality") Reported-by: Vaibhav Rustagi vaibhavrustagi@google.com Suggested-by: Peter Zijlstra peterz@infradead.org Suggested-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Nick Desaulniers ndesaulniers@google.com Tested-by: Vaibhav Rustagi vaibhavrustagi@google.com --- Changes v4 -> v5: * Add RETPOLINE_CFLAGS when CONFIG_RETPOLINE=y as per tglx. * Add tglx's Suggested-by tag. Changes v3 -> v4: * Use tabs to align flags (stylistic change only). * Drop stable tag, patch 01/02 doesn't apply earlier than 5.1. * Add tglx's suggested by tag for the tabs. * Carry Vaibhav's tested by tag from v3 since v4 is simply stylistic. Changes v2 -> v3: * Prefer $(CC_FLAGS_FTRACE) which is exported to -pg. * Also check CONFIG_STACKPROTECTOR and CONFIG_STACKPROTECTOR_STRONG. * Cc stable. Changes v1 -> v2: Rather than manually add -mno-sse, -mno-mmx, -mno-sse2, prefer to filter -pg flags.
arch/x86/purgatory/Makefile | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) arch/x86/purgatory/Makefile | 33 ++++++++++++++++++++++++++++----- 1 file changed, 28 insertions(+), 5 deletions(-)
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile index 91ef244026d2..8901a1f89cf5 100644 --- a/arch/x86/purgatory/Makefile +++ b/arch/x86/purgatory/Makefile @@ -20,11 +20,34 @@ KCOV_INSTRUMENT := n
# Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That # in turn leaves some undefined symbols like __fentry__ in purgatory and not -# sure how to relocate those. Like kexec-tools, use custom flags. - -KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes -fno-zero-initialized-in-bss -fno-builtin -ffreestanding -c -Os -mcmodel=large -KBUILD_CFLAGS += -m$(BITS) -KBUILD_CFLAGS += $(call cc-option,-fno-PIE) +# sure how to relocate those. +ifdef CONFIG_FUNCTION_TRACER +CFLAGS_REMOVE_sha256.o += $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_purgatory.o += $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_string.o += $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_kexec-purgatory.o += $(CC_FLAGS_FTRACE) +endif + +ifdef CONFIG_STACKPROTECTOR +CFLAGS_REMOVE_sha256.o += -fstack-protector +CFLAGS_REMOVE_purgatory.o += -fstack-protector +CFLAGS_REMOVE_string.o += -fstack-protector +CFLAGS_REMOVE_kexec-purgatory.o += -fstack-protector +endif + +ifdef CONFIG_STACKPROTECTOR_STRONG +CFLAGS_REMOVE_sha256.o += -fstack-protector-strong +CFLAGS_REMOVE_purgatory.o += -fstack-protector-strong +CFLAGS_REMOVE_string.o += -fstack-protector-strong +CFLAGS_REMOVE_kexec-purgatory.o += -fstack-protector-strong +endif + +ifdef CONFIG_RETPOLINE +CFLAGS_REMOVE_sha256.o += $(RETPOLINE_CFLAGS) +CFLAGS_REMOVE_purgatory.o += $(RETPOLINE_CFLAGS) +CFLAGS_REMOVE_string.o += $(RETPOLINE_CFLAGS) +CFLAGS_REMOVE_kexec-purgatory.o += $(RETPOLINE_CFLAGS) +endif
$(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE $(call if_changed,ld)