Patch "kbuild: Steal gcc's pie from the very beginning" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

kbuild: Steal gcc's pie from the very beginning

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
kbuild-steal-gcc-s-pie-from-the-very-beginning.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Borislav Petkov <[email protected]>
Date: Mon, 14 Nov 2016 19:41:31 +0100
Subject: kbuild: Steal gcc's pie from the very beginning

From: Borislav Petkov <[email protected]>

commit c6a385539175ebc603da53aafb7753d39089f32e upstream.

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.

---
 Makefile |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

@@ -395,11 +395,12 @@ KBUILD_CFLAGS   := -Wall -Wundef -Wstric
 		   -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

@@ -618,8 +619,6 @@ include arch/$(SRCARCH)/Makefile
 KBUILD_CFLAGS	+= $(call cc-option,-fno-delete-null-pointer-checks,)
 KBUILD_CFLAGS	+= $(call cc-disable-warning,maybe-uninitialized,)
 KBUILD_CFLAGS	+= $(call cc-disable-warning,frame-address,)
-KBUILD_CFLAGS	+= $(call cc-option,-fno-PIE)
-KBUILD_AFLAGS	+= $(call cc-option,-fno-PIE)
 
 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
 KBUILD_CFLAGS	+= -Os

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/x86-cpu-amd-fix-cpu_llc_id-for-amd-fam17h-systems.patch queue-4.4/kbuild-steal-gcc-s-pie-from-the-very-beginning.patch