This is needed to allow memory tools like KASAN and KMSAN see the
memory accesses from the checksum code. Without CONFIG_GENERIC_CSUM the
tools can't see memory accesses originating from handwritten assembly
code.
For KASAN it's a question of detecting more bugs, for KMSAN using the C
implementation also helps avoid false positives originating from
seemingly uninitialized checksum values.
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
To: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Michal Simek <monstr@xxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
---
v2:
- dropped the "default n" (as requested by Randy Dunlap)
Change-Id: I645e2c097253a8d5717ad87e2e2df6f6f67251f3
---
arch/x86/Kconfig | 4 ++++
arch/x86/include/asm/checksum.h | 10 +++++++---
arch/x86/lib/Makefile | 2 ++
3 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6d2b0fb3a871..9ea394f6513a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -272,6 +272,10 @@ config GENERIC_ISA_DMA
def_bool y
depends on ISA_DMA_API
+config GENERIC_CSUM
+ bool
+ default y if KMSAN || KASAN
+
config GENERIC_BUG
def_bool y
depends on BUG
diff --git a/arch/x86/include/asm/checksum.h b/arch/x86/include/asm/checksum.h
index d79d1e622dcf..ab3464cbce26 100644
--- a/arch/x86/include/asm/checksum.h
+++ b/arch/x86/include/asm/checksum.h
@@ -1,6 +1,10 @@
/* SPDX-License-Identifier: GPL-2.0 */
-#ifdef CONFIG_X86_32
-# include <asm/checksum_32.h>
+#ifdef CONFIG_GENERIC_CSUM
+# include <asm-generic/checksum.h>
#else
-# include <asm/checksum_64.h>
+# ifdef CONFIG_X86_32
+# include <asm/checksum_32.h>
+# else
+# include <asm/checksum_64.h>
+# endif
#endif
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 5246db42de45..bca9031de9ff 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -55,7 +55,9 @@ endif
lib-$(CONFIG_X86_USE_3DNOW) += mmx_32.o
else
obj-y += iomap_copy_64.o
+ifneq ($(CONFIG_GENERIC_CSUM),y)
lib-y += csum-partial_64.o csum-copy_64.o csum-wrappers_64.o
+endif
lib-y += clear_page_64.o copy_page_64.o
lib-y += memmove_64.o memset_64.o
lib-y += copy_user_64.o
--
2.24.0.rc0.303.g954a862665-goog
