linux-stable/scripts/Makefile.kasan
Arnd Bergmann 6baec880d7 kasan: turn off asan-stack for clang-8 and earlier
Building an arm64 allmodconfig kernel with clang results in over 140
warnings about overly large stack frames, the worst ones being:

  drivers/gpu/drm/panel/panel-sitronix-st7789v.c:196:12: error: stack frame size of 20224 bytes in function 'st7789v_prepare'
  drivers/video/fbdev/omap2/omapfb/displays/panel-tpo-td028ttec1.c:196:12: error: stack frame size of 13120 bytes in function 'td028ttec1_panel_enable'
  drivers/usb/host/max3421-hcd.c:1395:1: error: stack frame size of 10048 bytes in function 'max3421_spi_thread'
  drivers/net/wan/slic_ds26522.c:209:12: error: stack frame size of 9664 bytes in function 'slic_ds26522_probe'
  drivers/crypto/ccp/ccp-ops.c:2434:5: error: stack frame size of 8832 bytes in function 'ccp_run_cmd'
  drivers/media/dvb-frontends/stv0367.c:1005:12: error: stack frame size of 7840 bytes in function 'stv0367ter_algo'

None of these happen with gcc today, and almost all of these are the
result of a single known issue in llvm.  Hopefully it will eventually
get fixed with the clang-9 release.

In the meantime, the best idea I have is to turn off asan-stack for
clang-8 and earlier, so we can produce a kernel that is safe to run.

I have posted three patches that address the frame overflow warnings
that are not addressed by turning off asan-stack, so in combination with
this change, we get much closer to a clean allmodconfig build, which in
turn is necessary to do meaningful build regression testing.

It is still possible to turn on the CONFIG_ASAN_STACK option on all
versions of clang, and it's always enabled for gcc, but when
CONFIG_COMPILE_TEST is set, the option remains invisible, so
allmodconfig and randconfig builds (which are normally done with a
forced CONFIG_COMPILE_TEST) will still result in a mostly clean build.

Link: http://lkml.kernel.org/r/20190222222950.3997333-1-arnd@arndb.de
Link: https://bugs.llvm.org/show_bug.cgi?id=38809
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Qian Cai <cai@lca.pw>
Reviewed-by: Mark Brown <broonie@kernel.org>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-01 09:02:33 -08:00

56 lines
1.6 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0
ifdef CONFIG_KASAN_GENERIC
ifdef CONFIG_KASAN_INLINE
call_threshold := 10000
else
call_threshold := 0
endif
KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET)
CFLAGS_KASAN_MINIMAL := -fsanitize=kernel-address
cc-param = $(call cc-option, -mllvm -$(1), $(call cc-option, --param $(1)))
# -fasan-shadow-offset fails without -fsanitize
CFLAGS_KASAN_SHADOW := $(call cc-option, -fsanitize=kernel-address \
-fasan-shadow-offset=$(KASAN_SHADOW_OFFSET), \
$(call cc-option, -fsanitize=kernel-address \
-mllvm -asan-mapping-offset=$(KASAN_SHADOW_OFFSET)))
ifeq ($(strip $(CFLAGS_KASAN_SHADOW)),)
CFLAGS_KASAN := $(CFLAGS_KASAN_MINIMAL)
else
# Now add all the compiler specific options that are valid standalone
CFLAGS_KASAN := $(CFLAGS_KASAN_SHADOW) \
$(call cc-param,asan-globals=1) \
$(call cc-param,asan-instrumentation-with-call-threshold=$(call_threshold)) \
$(call cc-param,asan-stack=$(CONFIG_KASAN_STACK)) \
$(call cc-param,asan-use-after-scope=1) \
$(call cc-param,asan-instrument-allocas=1)
endif
ifdef CONFIG_KASAN_EXTRA
CFLAGS_KASAN += $(call cc-option, -fsanitize-address-use-after-scope)
endif
endif # CONFIG_KASAN_GENERIC
ifdef CONFIG_KASAN_SW_TAGS
ifdef CONFIG_KASAN_INLINE
instrumentation_flags := -mllvm -hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET)
else
instrumentation_flags := -mllvm -hwasan-instrument-with-calls=1
endif
CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
-mllvm -hwasan-instrument-stack=0 \
$(instrumentation_flags)
endif # CONFIG_KASAN_SW_TAGS
ifdef CONFIG_KASAN
CFLAGS_KASAN_NOSANITIZE := -fno-builtin
endif