2017-03-08 08:46:30 +00:00
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From e1c194ad704d298d6914e5b1efc4afee41a18a4c Mon Sep 17 00:00:00 2001
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From: Borislav Petkov <bp@suse.de>
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Date: Mon, 14 Nov 2016 19:41:31 +0100
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Subject: [PATCH] kbuild: Steal gcc's pie from the very beginning
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commit c6a385539175ebc603da53aafb7753d39089f32e upstream.
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So Sebastian turned off the PIE for kernel builds but that was too late
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- Kbuild.include already uses KBUILD_CFLAGS and trying to disable gcc
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options with, say cc-disable-warning, fails:
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gcc -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs
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...
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-Wno-sign-compare -fno-asynchronous-unwind-tables -Wframe-address -c -x c /dev/null -o .31392.tmp
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/dev/null:1:0: error: code model kernel does not support PIC mode
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because that returns an error and we can't disable the warning. For
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example in this case:
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KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
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which leads to gcc issuing all those warnings again.
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So let's turn off PIE/PIC at the earliest possible moment, when we
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declare KBUILD_CFLAGS so that cc-disable-warning picks it up too.
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Also, we need the $(call cc-option ...) because -fno-PIE is supported
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since gcc v3.4 and our lowest supported gcc version is 3.2 right now.
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Signed-off-by: Borislav Petkov <bp@suse.de>
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Cc: Ben Hutchings <ben@decadent.org.uk>
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Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Signed-off-by: Michal Marek <mmarek@suse.com>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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Makefile | 2 --
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1 file changed, 2 deletions(-)
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--- a/Makefile
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+++ b/Makefile
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@@ -619,8 +619,6 @@ include arch/$(SRCARCH)/Makefile
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KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,)
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KBUILD_CFLAGS += $(call cc-disable-warning,maybe-uninitialized,)
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KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
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-KBUILD_CFLAGS += $(call cc-option,-fno-PIE)
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-KBUILD_AFLAGS += $(call cc-option,-fno-PIE)
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ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
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2017-04-02 09:53:42 +00:00
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KBUILD_CFLAGS += -Os $(EXTRA_OPTIMIZATION)
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