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From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	j.neuschaefer@gmx.net, jniethe5@gmail.com
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH] powerpc/32: Fix boot failure with CONFIG_STACKPROTECTOR
Date: Thu, 29 Apr 2021 16:52:09 +0000 (UTC)	[thread overview]
Message-ID: <b688fe82927b330349d9e44553363fa451ea4d95.1619715114.git.christophe.leroy@csgroup.eu> (raw)

Commit 7c95d8893fb5 ("powerpc: Change calling convention for
create_branch() et. al.") complexified the frame of function
do_feature_fixups(), leading to GCC setting up a stack
guard when CONFIG_STACKPROTECTOR is selected.

The problem is that do_feature_fixups() is called very early
while 'current' in r2 is not set up yet and the code is still
not at the final address used at link time.

So, like other instrumentation, stack protection needs to be
deactivated for feature-fixups.c and code-patching.c

Reported-by: Jonathan Neuschaefer <j.neuschaefer@gmx.net>
Fixes: 7c95d8893fb5 ("powerpc: Change calling convention for create_branch() et. al.")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/lib/Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index f2c690ee75d1..cc1a8a0f311e 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -5,6 +5,9 @@
 
 ccflags-$(CONFIG_PPC64)	:= $(NO_MINIMAL_TOC)
 
+CFLAGS_code-patching.o += -fno-stack-protector
+CFLAGS_feature-fixups.o += -fno-stack-protector
+
 CFLAGS_REMOVE_code-patching.o = $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)
 
-- 
2.25.0


WARNING: multiple messages have this Message-ID (diff)
From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	 j.neuschaefer@gmx.net, jniethe5@gmail.com
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH] powerpc/32: Fix boot failure with CONFIG_STACKPROTECTOR
Date: Thu, 29 Apr 2021 16:52:09 +0000 (UTC)	[thread overview]
Message-ID: <b688fe82927b330349d9e44553363fa451ea4d95.1619715114.git.christophe.leroy@csgroup.eu> (raw)

Commit 7c95d8893fb5 ("powerpc: Change calling convention for
create_branch() et. al.") complexified the frame of function
do_feature_fixups(), leading to GCC setting up a stack
guard when CONFIG_STACKPROTECTOR is selected.

The problem is that do_feature_fixups() is called very early
while 'current' in r2 is not set up yet and the code is still
not at the final address used at link time.

So, like other instrumentation, stack protection needs to be
deactivated for feature-fixups.c and code-patching.c

Reported-by: Jonathan Neuschaefer <j.neuschaefer@gmx.net>
Fixes: 7c95d8893fb5 ("powerpc: Change calling convention for create_branch() et. al.")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/lib/Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index f2c690ee75d1..cc1a8a0f311e 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -5,6 +5,9 @@
 
 ccflags-$(CONFIG_PPC64)	:= $(NO_MINIMAL_TOC)
 
+CFLAGS_code-patching.o += -fno-stack-protector
+CFLAGS_feature-fixups.o += -fno-stack-protector
+
 CFLAGS_REMOVE_code-patching.o = $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)
 
-- 
2.25.0


             reply	other threads:[~2021-04-29 16:52 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-29 16:52 Christophe Leroy [this message]
2021-04-29 16:52 ` [PATCH] powerpc/32: Fix boot failure with CONFIG_STACKPROTECTOR Christophe Leroy
2021-04-29 17:49 ` Jonathan Neuschäfer
2021-04-29 17:49   ` Jonathan Neuschäfer

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