[PATCH 5.11 276/342] powerpc/32: Fix boot failure with CONFIG_STACKPROTECTOR

From: Greg Kroah-Hartman
Date: Mon May 10 2021 - 07:58:54 EST

From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>

commit f5668260b872e89b8d3942a8b7d4278aa9c2c981 upstream.

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

Fixes: 7c95d8893fb5 ("powerpc: Change calling convention for create_branch() et. al.")
Cc: stable@xxxxxxxxxxxxxxx # v5.8+
Reported-by: Jonathan Neuschaefer <j.neuschaefer@xxxxxxx>
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Tested-by: Jonathan Neuschaefer <j.neuschaefer@xxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/b688fe82927b330349d9e44553363fa451ea4d95.1619715114.git.christophe.leroy@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
arch/powerpc/lib/Makefile | 3 +++
1 file changed, 3 insertions(+)

--- 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)