On Sun, Feb 11, 2018 at 10:13:44AM -0800, Linus Torvalds wrote: > That actually sounds like we could just > > (a) make gcc 4.5 be the minimum required version > > (b) actually error out if we find a bad compiler So the unofficial plan was to enforce asm-goto and -fentry support by hard failure to build, which would get us at gcc-4.6 and then remove all the fallback cruft needed for those features -- for x86. If we want to do this tree wide, that's obviously OK with me too ;-) The below is the two force-asm-goto and force-fentry patches folded. --- Makefile | 17 +++++++++++------ arch/x86/Makefile | 25 +++++-------------------- 2 files changed, 16 insertions(+), 26 deletions(-) diff --git a/Makefile b/Makefile index d192dd826cce..1a46f23d0974 100644 --- a/Makefile +++ b/Makefile @@ -489,6 +489,17 @@ KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) endif +# check for 'asm goto' +ifeq ($(shell $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y) + CC_HAVE_ASM_GOTO := 1 + KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO + KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO +endif + +ifeq ($(call cc-option-yn, -mfentry), y) + CC_HAVE_FENTRY := 1 +endif + ifeq ($(config-targets),1) # =========================================================================== # *config targets only - make sure prerequisites are updated, and descend @@ -654,12 +665,6 @@ KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \ # Tell gcc to never replace conditional load with a non-conditional one KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0) -# check for 'asm goto' -ifeq ($(call shell-cached,$(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y) - KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO - KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO -endif - include scripts/Makefile.kcov include scripts/Makefile.gcc-plugins diff --git a/arch/x86/Makefile b/arch/x86/Makefile index fad55160dcb9..35cea458a7be 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -158,27 +158,12 @@ ifdef CONFIG_X86_X32 endif export CONFIG_X86_X32_ABI -# -# If the function graph tracer is used with mcount instead of fentry, -# '-maccumulate-outgoing-args' is needed to prevent a GCC bug -# (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109) -# -ifdef CONFIG_FUNCTION_GRAPH_TRACER - ifndef CONFIG_HAVE_FENTRY - ACCUMULATE_OUTGOING_ARGS := 1 - else - ifeq ($(call cc-option-yn, -mfentry), n) - ACCUMULATE_OUTGOING_ARGS := 1 - - # GCC ignores '-maccumulate-outgoing-args' when used with '-Os'. - # If '-Os' is enabled, disable it and print a warning. - ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE - undefine CONFIG_CC_OPTIMIZE_FOR_SIZE - $(warning Disabling CONFIG_CC_OPTIMIZE_FOR_SIZE. Your compiler does not have -mfentry so you cannot optimize for size with CONFIG_FUNCTION_GRAPH_TRACER.) - endif +ifndef CC_HAVE_ASM_GOTO + $(error Compiler lacks asm-goto support.) +endif - endif - endif +ifndef CC_HAVE_FENTRY + $(error Compiler lacks -mfentry support.) endif # -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
