+ x86-kmsan-use-c-versions-of-memset16-memset32-memset64.patch added to mm-unstable branch

+ x86-kmsan-use-c-versions-of-memset16-memset32-memset64.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: x86: kmsan: use C versions of memset16/memset32/memset64
has been added to the -mm mm-unstable branch.  Its filename is
     x86-kmsan-use-c-versions-of-memset16-memset32-memset64.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/x86-kmsan-use-c-versions-of-memset16-memset32-memset64.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Alexander Potapenko <glider@google.com>
Subject: x86: kmsan: use C versions of memset16/memset32/memset64
Date: Fri, 3 Mar 2023 15:14:32 +0100

KMSAN must see as many memory accesses as possible to prevent false
positive reports.  Fall back to versions of
memset16()/memset32()/memset64() implemented in lib/string.c instead of
those written in assembly.

Link: https://lkml.kernel.org/r/20230303141433.3422671-3-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Suggested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Helge Deller <deller@gmx.de>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---


--- a/arch/x86/include/asm/string_64.h~x86-kmsan-use-c-versions-of-memset16-memset32-memset64
+++ a/arch/x86/include/asm/string_64.h
@@ -22,6 +22,11 @@ extern void *__memcpy(void *to, const vo
 void *memset(void *s, int c, size_t n);
 void *__memset(void *s, int c, size_t n);
 
+/*
+ * KMSAN needs to instrument as much code as possible. Use C versions of
+ * memsetXX() from lib/string.c under KMSAN.
+ */
+#if !defined(CONFIG_KMSAN)
 #define __HAVE_ARCH_MEMSET16
 static inline void *memset16(uint16_t *s, uint16_t v, size_t n)
 {
@@ -57,6 +62,7 @@ static inline void *memset64(uint64_t *s
 		     : "memory");
 	return s;
 }
+#endif
 
 #define __HAVE_ARCH_MEMMOVE
 void *memmove(void *dest, const void *src, size_t count);
_

Patches currently in -mm which might be from glider@google.com are

x86-kmsan-dont-rename-memintrinsics-in-uninstrumented-files.patch
kmsan-another-take-at-fixing-memcpy-tests.patch
x86-kmsan-use-c-versions-of-memset16-memset32-memset64.patch
kmsan-add-memsetxx-tests.patch