Re: [PATCH] arm64: fix CONFIG_KASAN_SW_TAGS && CONFIG_KASAN_INLINE (was: Re: [PATCH V5 03/12] arm64: kasan: Switch to using) KASAN_SHADOW_OFFSET
From: Will Deacon <will@kernel.org>
Date: 2019-08-15 12:09:33
[+more kasan people and the kasan-dev list] On Wed, Aug 14, 2019 at 05:03:24PM +0100, Mark Rutland wrote:
On Wed, Aug 14, 2019 at 04:57:11PM +0100, Will Deacon wrote:quoted
On Wed, Aug 14, 2019 at 04:20:18PM +0100, Mark Rutland wrote:quoted
On Wed, Aug 07, 2019 at 04:55:15PM +0100, Steve Capper wrote:quoted
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index b2400f9c1213..2b7db0d41498 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile@@ -126,14 +126,6 @@ KBUILD_CFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT) KBUILD_CPPFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT) KBUILD_AFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT) -# KASAN_SHADOW_OFFSET = VA_START + (1 << (VA_BITS - KASAN_SHADOW_SCALE_SHIFT)) -# - (1 << (64 - KASAN_SHADOW_SCALE_SHIFT)) -# in 32-bit arithmetic -KASAN_SHADOW_OFFSET := $(shell printf "0x%08x00000000\n" $$(( \ - (0xffffffff & (-1 << ($(CONFIG_ARM64_VA_BITS) - 1 - 32))) \ - + (1 << ($(CONFIG_ARM64_VA_BITS) - 32 - $(KASAN_SHADOW_SCALE_SHIFT))) \ - - (1 << (64 - 32 - $(KASAN_SHADOW_SCALE_SHIFT))) )) ) - export TEXT_OFFSET GZFLAGS core-y += arch/arm64/kernel/ arch/arm64/mm/I've just spotted this breaks build using CONFIG_KASAN_SW_TAGS && CONFIG_KASAN_INLINE, as scripts/Makefile.kasan only propagates CONFIG_KASAN_SHADOW_OFFSET into KASAN_SHADOW_OFFSET when CONFIG_KASAN_GENERIC is selected, but consumes KASAN_SHADOW_OFFSET regardless. I think that's by accident rather than by design, but to minimize/localize the fixup, how about the below? I can send a cleanup patch for scripts/Makefile.kasan later.How much work is that? I've dropped this stuff from -next for now, so we have time to fix it properly as long as it's not going to take weeks.I wrote it first, so no effort; patch below.
The patch looks fine to me, but I'd like an Ack from one of the KASAN folks before I queue this via the arm64 tree (where support for 52-bit virtual addressing in the kernel [1] depends on this being fixed). Patch is quoted below. Please can somebody take a look? Thanks, Will [1] https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/log/?h=for-next/52-bit-kva
quoted hunk ↗ jump to hunk
From ecdf60051a850f817d98f84ae9011afa2311b8f1 Mon Sep 17 00:00:00 2001 From: Mark Rutland <mark.rutland@arm.com> Date: Wed, 14 Aug 2019 15:31:57 +0100 Subject: [PATCH] kasan/arm64: fix CONFIG_KASAN_SW_TAGS && KASAN_INLINE The generic Makefile.kasan propagates CONFIG_KASAN_SHADOW_OFFSET into KASAN_SHADOW_OFFSET, but only does so for CONFIG_KASAN_GENERIC. Since commit: 6bd1d0be0e97936d ("arm64: kasan: Switch to using KASAN_SHADOW_OFFSET") ... arm64 defines CONFIG_KASAN_SHADOW_OFFSET in Kconfig rather than defining KASAN_SHADOW_OFFSET in a Makefile. Thus, if CONFIG_KASAN_SW_TAGS && KASAN_INLINE are selected, we get build time splats due to KASAN_SHADOW_OFFSET not being set: | [mark@lakrids:~/src/linux]% usellvm 8.0.1 usekorg 8.1.0 make ARCH=arm64 CROSS_COMPILE=aarch64-linux- CC=clang | scripts/kconfig/conf --syncconfig Kconfig | CC scripts/mod/empty.o | clang (LLVM option parsing): for the -hwasan-mapping-offset option: '' value invalid for uint argument! | scripts/Makefile.build:273: recipe for target 'scripts/mod/empty.o' failed | make[1]: *** [scripts/mod/empty.o] Error 1 | Makefile:1123: recipe for target 'prepare0' failed | make: *** [prepare0] Error 2 Let's fix this by always propagating CONFIG_KASAN_SHADOW_OFFSET into KASAN_SHADOW_OFFSET if CONFIG_KASAN is selected, moving the existing common definition of +CFLAGS_KASAN_NOSANITIZE to the top of Makefile.kasan. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Andrey Ryabinin <redacted> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Steve Capper <redacted> Cc: Will Deacon <will@kernel.org> --- scripts/Makefile.kasan | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan index 6410bd22fe38..03757cc60e06 100644 --- a/scripts/Makefile.kasan +++ b/scripts/Makefile.kasan@@ -1,4 +1,9 @@ # SPDX-License-Identifier: GPL-2.0 +ifdef CONFIG_KASAN +CFLAGS_KASAN_NOSANITIZE := -fno-builtin +KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET) +endif + ifdef CONFIG_KASAN_GENERIC ifdef CONFIG_KASAN_INLINE@@ -7,8 +12,6 @@ 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)))@@ -45,7 +48,3 @@ CFLAGS_KASAN := -fsanitize=kernel-hwaddress \ $(instrumentation_flags) endif # CONFIG_KASAN_SW_TAGS - -ifdef CONFIG_KASAN -CFLAGS_KASAN_NOSANITIZE := -fno-builtin -endif-- 2.11.0
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