| Message ID | 20090216142001.GA27869@oksana.dev.rtsoft.ru (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Mon, Feb 16, 2009 at 05:20:01PM +0300, Anton Vorontsov wrote: > On Sat, Feb 14, 2009 at 08:57:02PM +0100, Sam Ravnborg wrote: > [...] > > > > --- a/Makefile > > > > +++ b/Makefile > > > > @@ -525,8 +525,6 @@ else > > > > KBUILD_CFLAGS += -O2 > > > > endif > > > > > > > > -include $(srctree)/arch/$(SRCARCH)/Makefile > > > > - > > > > ifneq (CONFIG_FRAME_WARN,0) > > > > KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN}) > > > > endif > > > > @@ -555,6 +553,8 @@ ifdef CONFIG_DEBUG_SECTION_MISMATCH > > > > KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once) > > > > endif > > > > > > > > +include $(srctree)/arch/$(SRCARCH)/Makefile > > > > + > > > > # arch Makefile may override CC so keep this after arch Makefile is included > > > > NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) > > > > CHECKFLAGS += $(NOSTDINC_FLAGS) > > > > -- > > > > > > this patch is really for Sam to judge - Cc:-ed him. > > > > If we move the include further down then the following: > > > > # Force gcc to behave correct even for buggy distributions > > # Arch Makefiles may override this setting > > KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) > > > > will most likely fail. > > Hm... I don't get it, the comment says that the arch "may override > this setting", but currently it may not, since arch makefile is > included before this line. So my patch also fixes this "bug", no? > > Or arches supposed to overwrite "cc-option" behaviour? Hm.. > > There is an interesting commit: > > commit e06b8b98da071f7dd78fb7822991694288047df0 > Author: Sam Ravnborg <sam@ravnborg.org> > Date: Wed Feb 13 22:43:28 2008 +0100 > > kbuild: allow -fstack-protector to take effect > [...] > --- a/Makefile > +++ b/Makefile > @@ -507,6 +507,10 @@ else > KBUILD_CFLAGS += -O2 > endif > > +# Force gcc to behave correct even for buggy distributions > +# Arch Makefiles may override this setting > +KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) > + > include $(srctree)/arch/$(SRCARCH)/Makefile > > ifdef CONFIG_FRAME_POINTER > @@ -525,9 +529,6 @@ ifdef CONFIG_DEBUG_SECTION_MISMATCH > KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once) > endif > > -# Force gcc to behave correct even for buggy distributions > -KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) > - > # arch Makefile may override CC so keep this after arch Makefile is included > NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) > CHECKFLAGS += $(NOSTDINC_FLAGS) > > > ^^ Which does the same (wrt fno-stack-protector) as the patch I > sent, i.e. includes arch Makefile later. > > But then, this commit reverted things back (w/o your Ack): > > commit bef5b54bd7bf8117c75cb943d64549134c6d9a1f > Author: Ralf Baechle <ralf@linux-mips.org> > Date: Wed Jul 16 13:02:24 2008 +0100 > > Fix MIPS cross-compile problem > [...] > Signed-off-by: Ralf Baechle <ralf@linux-mips.org> > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Ok, I think I got it. It seems that Ralf was using this feature of arch/mips/Makefile: ifneq ($(SUBARCH),$(ARCH)) ifeq ($(CROSS_COMPILE),) CROSS_COMPILE := $(call cc-cross-prefix, $(tool-archpref)-linux- $(tool-archpref)-linux-gnu- $(tool-archpref)-unknown-linux-gnu-) endif endif There are few arches that have "auto detection" of CROSS_COMPILE variable: mips, m68k, parisc, xtensa, h8300 and blackfin. So `normal' arches don't have any chance to overwrite the flags because of the few offenders above. ;-) > [...] > --- a/Makefile > +++ b/Makefile > @@ -508,6 +508,8 @@ else > KBUILD_CFLAGS += -O2 > endif > > +include $(srctree)/arch/$(SRCARCH)/Makefile > + > ifneq (CONFIG_FRAME_WARN,0) > KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN}) > endif > @@ -516,8 +518,6 @@ endif > # Arch Makefiles may override this setting > KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) > > -include $(srctree)/arch/$(SRCARCH)/Makefile > - > ifdef CONFIG_FRAME_POINTER > KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls > else
On Mon, Feb 16, 2009 at 05:20:01PM +0300, Anton Vorontsov wrote: [...] > But then, this commit reverted things back (w/o your Ack): > > commit bef5b54bd7bf8117c75cb943d64549134c6d9a1f > Author: Ralf Baechle <ralf@linux-mips.org> > Date: Wed Jul 16 13:02:24 2008 +0100 > > Fix MIPS cross-compile problem > [...] > Signed-off-by: Ralf Baechle <ralf@linux-mips.org> > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> > > [...] > --- a/Makefile > +++ b/Makefile > @@ -508,6 +508,8 @@ else > KBUILD_CFLAGS += -O2 > endif > > +include $(srctree)/arch/$(SRCARCH)/Makefile > + > ifneq (CONFIG_FRAME_WARN,0) > KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN}) > endif > @@ -516,8 +518,6 @@ endif > # Arch Makefiles may override this setting > KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) > > -include $(srctree)/arch/$(SRCARCH)/Makefile > - > ifdef CONFIG_FRAME_POINTER > KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls > else Btw, I wonder if x86's CONFIG_CC_STACKPROTECTOR is a no-op since v2.6.27-rc1? Seems like it is.
* Anton Vorontsov <avorontsov@ru.mvista.com> wrote: > On Mon, Feb 16, 2009 at 05:20:01PM +0300, Anton Vorontsov wrote: > [...] > > But then, this commit reverted things back (w/o your Ack): > > > > commit bef5b54bd7bf8117c75cb943d64549134c6d9a1f > > Author: Ralf Baechle <ralf@linux-mips.org> > > Date: Wed Jul 16 13:02:24 2008 +0100 > > > > Fix MIPS cross-compile problem > > [...] > > Signed-off-by: Ralf Baechle <ralf@linux-mips.org> > > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> > > > > [...] > > --- a/Makefile > > +++ b/Makefile > > @@ -508,6 +508,8 @@ else > > KBUILD_CFLAGS += -O2 > > endif > > > > +include $(srctree)/arch/$(SRCARCH)/Makefile > > + > > ifneq (CONFIG_FRAME_WARN,0) > > KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN}) > > endif > > @@ -516,8 +518,6 @@ endif > > # Arch Makefiles may override this setting > > KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) > > > > -include $(srctree)/arch/$(SRCARCH)/Makefile > > - > > ifdef CONFIG_FRAME_POINTER > > KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls > > else > > Btw, I wonder if x86's CONFIG_CC_STACKPROTECTOR is a no-op since > v2.6.27-rc1? Seems like it is. that's fixed and merged up for 2.6.30. Ingo
> > There are few arches that have "auto detection" of CROSS_COMPILE > variable: mips, m68k, parisc, xtensa, h8300 and blackfin. > > So `normal' arches don't have any chance to overwrite the flags > because of the few offenders above. ;-) We also have archs where we add options to gcc that may impact for example -fno-stack-protector. We had a bug in x86 in this area for a while. So the only sane thing is to only add the most generic options to KBUILD_CFLAGS before we include the arch specific part. And we can then add the conditional options later - like the KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) in this case. We learned a few lessons in this area over time as your history digging also showed. Sam
--- a/Makefile +++ b/Makefile @@ -507,6 +507,10 @@ else KBUILD_CFLAGS += -O2 endif +# Force gcc to behave correct even for buggy distributions +# Arch Makefiles may override this setting +KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) + include $(srctree)/arch/$(SRCARCH)/Makefile ifdef CONFIG_FRAME_POINTER @@ -525,9 +529,6 @@ ifdef CONFIG_DEBUG_SECTION_MISMATCH KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once) endif -# Force gcc to behave correct even for buggy distributions -KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) - # arch Makefile may override CC so keep this after arch Makefile is included NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) CHECKFLAGS += $(NOSTDINC_FLAGS) ^^ Which does the same (wrt fno-stack-protector) as the patch I sent, i.e. includes arch Makefile later. But then, this commit reverted things back (w/o your Ack): commit bef5b54bd7bf8117c75cb943d64549134c6d9a1f Author: Ralf Baechle <ralf@linux-mips.org> Date: Wed Jul 16 13:02:24 2008 +0100 Fix MIPS cross-compile problem [...] Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [...] --- a/Makefile +++ b/Makefile @@ -508,6 +508,8 @@ else KBUILD_CFLAGS += -O2 endif +include $(srctree)/arch/$(SRCARCH)/Makefile + ifneq (CONFIG_FRAME_WARN,0) KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN}) endif @@ -516,8 +518,6 @@ endif # Arch Makefiles may override this setting KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) -include $(srctree)/arch/$(SRCARCH)/Makefile - ifdef CONFIG_FRAME_POINTER KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls else