On Mon, Nov 14, 2016 at 09:14:57PM +0100, Sebastian Andrzej Siewior wrote: > This also means that all feature tests fail unless the -fno-PIE is > there. > > Acked-by: Sebastian Andrzej Siewior <[email protected]> > > 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…
Ah yes, here's a v1.1. Let's leave the cc-option check until we sort out the min supported gcc version. CC: stable too. Thanks! --- From: Borislav Petkov <[email protected]> Date: Mon, 14 Nov 2016 19:41:31 +0100 Subject: [PATCH] kbuild: Steal gcc's pie from the very beginning 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. Also, we need the $(call cc-option ...) because -fno-PIE is supported since gcc v3.4 and our lowest supported gcc version is 3.2 right now. Signed-off-by: Borislav Petkov <[email protected]> Cc: [email protected] Cc: Ben Hutchings <[email protected]> Cc: Michal Marek <[email protected]> Cc: Sebastian Andrzej Siewior <[email protected]> --- Makefile | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/Makefile b/Makefile index 3ff1fb26d8b2..9bc877d073d7 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 $(call cc-option,-fno-PIE) + KBUILD_AFLAGS_KERNEL := KBUILD_CFLAGS_KERNEL := -KBUILD_AFLAGS := -D__ASSEMBLY__ +KBUILD_AFLAGS := -D__ASSEMBLY__ $(call cc-option,-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,) -- 2.10.0 -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.
