| Message ID | 20201013003203.4168817-8-samitolvanen@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | Add support for Clang LTO | expand |
On Mon, Oct 12, 2020 at 05:31:45PM -0700, Sami Tolvanen wrote: > This change removes all instances of DISABLE_LTO from > Makefiles, as they are currently unused, and the preferred > method of disabling LTO is to filter out the flags instead. > > Suggested-by: Kees Cook <keescook@chromium.org> > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > Reviewed-by: Kees Cook <keescook@chromium.org> Hi Masahiro, Since this is independent of anything else and could be seen as a general cleanup, can this patch be taken into your tree, just to separate it from the list of dependencies for this series? -Kees
On Thu, Oct 15, 2020 at 7:43 AM Kees Cook <keescook@chromium.org> wrote: > > On Mon, Oct 12, 2020 at 05:31:45PM -0700, Sami Tolvanen wrote: > > This change removes all instances of DISABLE_LTO from > > Makefiles, as they are currently unused, and the preferred > > method of disabling LTO is to filter out the flags instead. > > > > Suggested-by: Kees Cook <keescook@chromium.org> > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > > Reviewed-by: Kees Cook <keescook@chromium.org> > > Hi Masahiro, > > Since this is independent of anything else and could be seen as a > general cleanup, can this patch be taken into your tree, just to > separate it from the list of dependencies for this series? > > -Kees > > -- > Kees Cook Yes, this is stale code because GCC LTO was not pulled. Applied to linux-kbuild. I added the following historical background. Note added by Masahiro Yamada: DISABLE_LTO was added as preparation for GCC LTO, but GCC LTO was not pulled into the mainline. (https://lkml.org/lkml/2014/4/8/272)
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile index 45d5cfe46429..e836e300440f 100644 --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile @@ -31,7 +31,6 @@ ccflags-y := -fno-common -fno-builtin -fno-stack-protector -ffixed-x18 ccflags-y += -DDISABLE_BRANCH_PROFILING CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) $(GCC_PLUGINS_CFLAGS) -KBUILD_CFLAGS += $(DISABLE_LTO) KASAN_SANITIZE := n UBSAN_SANITIZE := n OBJECT_FILES_NON_STANDARD := y diff --git a/arch/sparc/vdso/Makefile b/arch/sparc/vdso/Makefile index f44355e46f31..476c4b315505 100644 --- a/arch/sparc/vdso/Makefile +++ b/arch/sparc/vdso/Makefile @@ -3,8 +3,6 @@ # Building vDSO images for sparc. # -KBUILD_CFLAGS += $(DISABLE_LTO) - VDSO64-$(CONFIG_SPARC64) := y VDSOCOMPAT-$(CONFIG_COMPAT) := y diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index 215376d975a2..ecc27018ae13 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -9,8 +9,6 @@ ARCH_REL_TYPE_ABS := R_X86_64_JUMP_SLOT|R_X86_64_GLOB_DAT|R_X86_64_RELATIVE| ARCH_REL_TYPE_ABS += R_386_GLOB_DAT|R_386_JMP_SLOT|R_386_RELATIVE include $(srctree)/lib/vdso/Makefile -KBUILD_CFLAGS += $(DISABLE_LTO) - # Sanitizer runtimes are unavailable and cannot be linked here. KASAN_SANITIZE := n UBSAN_SANITIZE := n diff --git a/kernel/Makefile b/kernel/Makefile index 16ec9262ce9d..2561abc91961 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -38,9 +38,6 @@ KASAN_SANITIZE_kcov.o := n KCSAN_SANITIZE_kcov.o := n CFLAGS_kcov.o := $(call cc-option, -fno-conserve-stack) -fno-stack-protector -# cond_syscall is currently not LTO compatible -CFLAGS_sys_ni.o = $(DISABLE_LTO) - obj-y += sched/ obj-y += locking/ obj-y += power/ diff --git a/scripts/Makefile.build b/scripts/Makefile.build index cd4294435fef..6db5b1f55b14 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -111,7 +111,7 @@ endif # --------------------------------------------------------------------------- quiet_cmd_cc_s_c = CC $(quiet_modtag) $@ - cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS), $(c_flags)) $(DISABLE_LTO) -fverbose-asm -S -o $@ $< + cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS), $(c_flags)) -fverbose-asm -S -o $@ $< $(obj)/%.s: $(src)/%.c FORCE $(call if_changed_dep,cc_s_c)