x86: kmsan: handle open-coded assembly in lib/iomem.c

KMSAN cannot intercept memory accesses within asm() statements.  That's
why we add kmsan_unpoison_memory() and kmsan_check_memory() to hint it how
to handle memory copied from/to I/O memory.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Alexander Potapenko <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Herbert Xu <[email protected]>
Cc: Ilya Leoshkevich <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Vegard Nossum <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/x86/lib/iomem.c b/arch/x86/lib/iomem.c
index 3e2f33fc33de..e0411a3774d4 100644
--- a/arch/x86/lib/iomem.c
+++ b/arch/x86/lib/iomem.c
@@ -1,6 +1,7 @@
 #include <linux/string.h>
 #include <linux/module.h>
 #include <linux/io.h>
+#include <linux/kmsan-checks.h>
 
 #define movs(type,to,from) \
 	asm volatile("movs" type:"=&D" (to), "=&S" (from):"0" (to), "1" (from):"memory")
@@ -37,6 +38,8 @@ static void string_memcpy_fromio(void *to, const volatile void __iomem *from, si
 		n-=2;
 	}
 	rep_movs(to, (const void *)from, n);
+	/* KMSAN must treat values read from devices as initialized. */
+	kmsan_unpoison_memory(to, n);
 }
 
 static void string_memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
@@ -44,6 +47,8 @@ static void string_memcpy_toio(volatile void __iomem *to, const void *from, size
 	if (unlikely(!n))
 		return;
 
+	/* Make sure uninitialized memory isn't copied to devices. */
+	kmsan_check_memory(from, n);
 	/* Align any unaligned destination IO */
 	if (unlikely(1 & (unsigned long)to)) {
 		movs("b", to, from);