From: Ard Biesheuvel <ardb@xxxxxxxxxx>
commit 89604523a76eb3e13014b2bdab7f8870becee284 upstream.
When using plugins, GCC requires that the -fplugin= options precedes
any of its plugin arguments appearing on the command line as well.
This is usually not a concern, but as it turns out, this requirement
is causing some issues with ARM's per-task stack protector plugin
and Kbuild's implementation of $(cc-option).
When the per-task stack protector plugin is enabled, and we tweak
the implementation of cc-option not to pipe the stderr output of
GCC to /dev/null, the following output is generated when GCC is
executed in the context of cc-option:
cc1: error: plugin arm_ssp_per_task_plugin should be specified before \
-fplugin-arg-arm_ssp_per_task_plugin-tso=1 in the command line
cc1: error: plugin arm_ssp_per_task_plugin should be specified before \
-fplugin-arg-arm_ssp_per_task_plugin-offset=24 in the command line
These errors will cause any option passed to cc-option to be treated
as unsupported, which is obviously incorrect.
The cause of this issue is the fact that the -fplugin= argument is
added to GCC_PLUGINS_CFLAGS, whereas the arguments above are added
to KBUILD_CFLAGS, and the contents of the former get filtered out of
the latter before being passed to the GCC running the cc-option test,
and so the -fplugin= option does not appear at all on the GCC command
line.
Adding the arguments to GCC_PLUGINS_CFLAGS instead of KBUILD_CFLAGS
would be the correct approach here, if it weren't for the fact that we
are using $(eval) to defer the moment that they are added until after
asm-offsets.h is generated, which is after the point where the contents
of GCC_PLUGINS_CFLAGS are added to KBUILD_CFLAGS. So instead, we have
to add our plugin arguments to both.
For similar reasons, we cannot append DISABLE_ARM_SSP_PER_TASK_PLUGIN
to KBUILD_CFLAGS, as it will be passed to GCC when executing in the
context of cc-option, whereas the other plugin arguments will have
been filtered out, resulting in a similar error and false negative
result as above. So add it to ccflags-y instead.
Fixes: 189af4657186da08 ("ARM: smp: add support for per-task stack canaries")
Reported-by: Merlijn Wajer <merlijn@xxxxxxxxxx>
Tested-by: Tony Lindgren <tony@xxxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/Makefile | 4 +++-
arch/arm/boot/compressed/Makefile | 4 ++--
2 files changed, 5 insertions(+), 3 deletions(-)
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -307,13 +307,15 @@ endif
ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)
prepare: stack_protector_prepare
stack_protector_prepare: prepare0
- $(eval KBUILD_CFLAGS += \
+ $(eval SSP_PLUGIN_CFLAGS := \
-fplugin-arg-arm_ssp_per_task_plugin-tso=$(shell \
awk '{if ($$2 == "THREAD_SZ_ORDER") print $$3;}'\
include/generated/asm-offsets.h) \
-fplugin-arg-arm_ssp_per_task_plugin-offset=$(shell \
awk '{if ($$2 == "TI_STACK_CANARY") print $$3;}'\
include/generated/asm-offsets.h))
+ $(eval KBUILD_CFLAGS += $(SSP_PLUGIN_CFLAGS))
+ $(eval GCC_PLUGINS_CFLAGS += $(SSP_PLUGIN_CFLAGS))
endif
all: $(notdir $(KBUILD_IMAGE))
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -101,7 +101,6 @@ clean-files += piggy_data lib1funcs.S as
$(libfdt) $(libfdt_hdrs) hyp-stub.S
KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
-KBUILD_CFLAGS += $(DISABLE_ARM_SSP_PER_TASK_PLUGIN)
ifeq ($(CONFIG_FUNCTION_TRACER),y)
ORIG_CFLAGS := $(KBUILD_CFLAGS)
@@ -117,7 +116,8 @@ CFLAGS_fdt_ro.o := $(nossp_flags)
CFLAGS_fdt_rw.o := $(nossp_flags)
CFLAGS_fdt_wip.o := $(nossp_flags)
-ccflags-y := -fpic $(call cc-option,-mno-single-pic-base,) -fno-builtin -I$(obj)
+ccflags-y := -fpic $(call cc-option,-mno-single-pic-base,) -fno-builtin \
+ -I$(obj) $(DISABLE_ARM_SSP_PER_TASK_PLUGIN)
asflags-y := -DZIMAGE
# Supply kernel BSS size to the decompressor via a linker symbol.
