| Message ID | 20161114185130.30641-1-bp@alien8.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2016-11-14 19:51:30 [+0100], Borislav Petkov wrote: > From: Borislav Petkov <bp@suse.de> > > So Sebastian turned off the PIE for kernel builds but that was too late > - Kbuild.include already uses KBUILD_CFLAGS and trying to disable gcc > options with, say cc-disable-warning, fails: > > gcc -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs > ... > -Wno-sign-compare -fno-asynchronous-unwind-tables -Wframe-address -c -x c /dev/null -o .31392.tmp > /dev/null:1:0: error: code model kernel does not support PIC mode > > because that returns an error and we can't disable the warning. For > example in this case: > > KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,) > > which leads to gcc issuing all those warnings again. This also means that all feature tests fail unless the -fno-PIE is there. Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> This thing gcc v3.4 only but I intend to update the min requirement to alteast gcc v3.4 to cover this. As per hpa gcc v3.4 is the lowest version should be used for x86… Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Dne 14.11.2016 v 19:51 Borislav Petkov napsal(a): > From: Borislav Petkov <bp@suse.de> > > So Sebastian turned off the PIE for kernel builds but that was too late > - Kbuild.include already uses KBUILD_CFLAGS and trying to disable gcc > options with, say cc-disable-warning, fails: > > gcc -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs > ... > -Wno-sign-compare -fno-asynchronous-unwind-tables -Wframe-address -c -x c /dev/null -o .31392.tmp > /dev/null:1:0: error: code model kernel does not support PIC mode > > because that returns an error and we can't disable the warning. For > example in this case: > > KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,) > > which leads to gcc issuing all those warnings again. > > So let's turn off PIE/PIC at the earliest possible moment, when we > declare KBUILD_CFLAGS so that cc-disable-warning picks it up too. > > Signed-off-by: Borislav Petkov <bp@suse.de> > Cc: Ben Hutchings <ben@decadent.org.uk> > Cc: Michal Marek <mmarek@suse.com> > Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- > Makefile | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/Makefile b/Makefile > index 3ff1fb26d8b2..5558cc5b1505 100644 > --- a/Makefile > +++ b/Makefile > @@ -399,11 +399,12 @@ KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ > -fno-strict-aliasing -fno-common \ > -Werror-implicit-function-declaration \ > -Wno-format-security \ > - -std=gnu89 > + -std=gnu89 -fno-PIE Please use the cc-option variant, otherwise good catch. Michal -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Makefile b/Makefile index 3ff1fb26d8b2..5558cc5b1505 100644 --- a/Makefile +++ b/Makefile @@ -399,11 +399,12 @@ KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ -fno-strict-aliasing -fno-common \ -Werror-implicit-function-declaration \ -Wno-format-security \ - -std=gnu89 + -std=gnu89 -fno-PIE + KBUILD_AFLAGS_KERNEL := KBUILD_CFLAGS_KERNEL := -KBUILD_AFLAGS := -D__ASSEMBLY__ +KBUILD_AFLAGS := -D__ASSEMBLY__ -fno-PIE KBUILD_AFLAGS_MODULE := -DMODULE KBUILD_CFLAGS_MODULE := -DMODULE KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds @@ -621,8 +622,6 @@ include arch/$(SRCARCH)/Makefile KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,) KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,) -KBUILD_CFLAGS += $(call cc-option,-fno-PIE) -KBUILD_AFLAGS += $(call cc-option,-fno-PIE) ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION KBUILD_CFLAGS += $(call cc-option,-ffunction-sections,)