Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b674f791 authored by Nick Desaulniers's avatar Nick Desaulniers Committed by Greg Kroah-Hartman
Browse files

x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS 



commit b059f801a937d164e03b33c1848bb3dca67c0b04 upstream.

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.

Fixes: 8fc5b4d4 ("purgatory: core purgatory functionality")
Reported-by: default avatarVaibhav Rustagi <vaibhavrustagi@google.com>
Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
Suggested-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarVaibhav Rustagi <vaibhavrustagi@google.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190807221539.94583-2-ndesaulniers@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0a9e41e2

arch/x86/purgatory/Makefile

+28 −5
Original line number Diff line number Diff line
@@ -17,11 +17,34 @@ 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)