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Subject[PATCH 37/43] x86: kasan: kmsan: support CONFIG_GENERIC_CSUM on x86, enable it for KASAN/KMSAN
From
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@google.com>

---

Link: https://linux-review.googlesource.com/id/I3e95247be55b1112af59dbba07e8cbf34e50a581
---
arch/x86/Kconfig | 4 ++++
arch/x86/include/asm/checksum.h | 16 ++++++++++------
arch/x86/lib/Makefile | 2 ++
3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5c2ccb85f2efb..760570ff3f3e4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -310,6 +310,10 @@ 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 bca625a60186c..6df6ece8a28ec 100644
--- a/arch/x86/include/asm/checksum.h
+++ b/arch/x86/include/asm/checksum.h
@@ -1,9 +1,13 @@
/* SPDX-License-Identifier: GPL-2.0 */
-#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER 1
-#define HAVE_CSUM_COPY_USER
-#define _HAVE_ARCH_CSUM_AND_COPY
-#ifdef CONFIG_X86_32
-# include <asm/checksum_32.h>
+#ifdef CONFIG_GENERIC_CSUM
+# include <asm-generic/checksum.h>
#else
-# include <asm/checksum_64.h>
+# define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER 1
+# define HAVE_CSUM_COPY_USER
+# define _HAVE_ARCH_CSUM_AND_COPY
+# 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 c6506c6a70922..81be8498353a6 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -66,7 +66,9 @@ 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
--
2.34.1.173.g76aa8bc2d0-goog
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