[PATCH 12/13] powerpc/string: Add KMSAN support

[Nicholas Miehlbradt]

KMSAN expects functions __mem{set,cpy,move} so add aliases pointing to
the respective functions.

Disable use of architecture specific memset{16,32,64} to ensure that
metadata is correctly updated and strn{cpy,cmp} and mem{chr,cmp} which
are implemented in assembly and therefore cannot be instrumented to
propagate/check metadata.

Alias calls to mem{set,cpy,move} to __msan_mem{set,cpy,move} in
instrumented code to correctly propagate metadata.

Signed-off-by: Nicholas Miehlbradt <nicholas at linux.ibm.com>
---
 arch/powerpc/include/asm/kmsan.h               |  7 +++++++
 arch/powerpc/include/asm/string.h              | 18 ++++++++++++++++--
 arch/powerpc/lib/Makefile                      |  2 ++
 arch/powerpc/lib/mem_64.S                      |  5 ++++-
 arch/powerpc/lib/memcpy_64.S                   |  2 ++
 .../selftests/powerpc/copyloops/asm/kmsan.h    |  0
 .../selftests/powerpc/copyloops/linux/export.h |  1 +
 7 files changed, 32 insertions(+), 3 deletions(-)
 create mode 100644 tools/testing/selftests/powerpc/copyloops/asm/kmsan.h

diff --git a/arch/powerpc/include/asm/kmsan.h b/arch/powerpc/include/asm/kmsan.h
index bc84f6ff2ee9..fc59dc24e170 100644
--- a/arch/powerpc/include/asm/kmsan.h
+++ b/arch/powerpc/include/asm/kmsan.h
@@ -7,6 +7,13 @@
 #ifndef _ASM_POWERPC_KMSAN_H
 #define _ASM_POWERPC_KMSAN_H
 
+#ifdef CONFIG_KMSAN
+#define EXPORT_SYMBOL_KMSAN(fn) SYM_FUNC_ALIAS(__##fn, fn) \
+				EXPORT_SYMBOL(__##fn)
+#else
+#define EXPORT_SYMBOL_KMSAN(fn)
+#endif
+
 #ifndef __ASSEMBLY__
 #ifndef MODULE
 
diff --git a/arch/powerpc/include/asm/string.h b/arch/powerpc/include/asm/string.h
index 60ba22770f51..412626ce619b 100644
--- a/arch/powerpc/include/asm/string.h
+++ b/arch/powerpc/include/asm/string.h
@@ -4,7 +4,7 @@
 
 #ifdef __KERNEL__
 
-#ifndef CONFIG_KASAN
+#if !defined(CONFIG_KASAN) && !defined(CONFIG_KMSAN)
 #define __HAVE_ARCH_STRNCPY
 #define __HAVE_ARCH_STRNCMP
 #define __HAVE_ARCH_MEMCHR
@@ -56,8 +56,22 @@ void *__memmove(void *to, const void *from, __kernel_size_t n);
 #endif /* CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX */
 #endif /* CONFIG_KASAN */
 
+#ifdef CONFIG_KMSAN
+
+void *__memset(void *s, int c, __kernel_size_t count);
+void *__memcpy(void *to, const void *from, __kernel_size_t n);
+void *__memmove(void *to, const void *from, __kernel_size_t n);
+
+#ifdef __SANITIZE_MEMORY__
+#include <linux/kmsan_string.h>
+#define memset __msan_memset
+#define memcpy __msan_memcpy
+#define memmove __msan_memmove
+#endif
+#endif /* CONFIG_KMSAN */
+
 #ifdef CONFIG_PPC64
-#ifndef CONFIG_KASAN
+#if !defined(CONFIG_KASAN) && !defined(CONFIG_KMSAN)
 #define __HAVE_ARCH_MEMSET32
 #define __HAVE_ARCH_MEMSET64
 
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 51ad0397c17a..fc3ea3eebbd6 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -32,9 +32,11 @@ obj-y += code-patching.o feature-fixups.o pmem.o
 obj-$(CONFIG_CODE_PATCHING_SELFTEST) += test-code-patching.o
 
 ifndef CONFIG_KASAN
+ifndef CONFIG_KMSAN
 obj-y	+=	string.o memcmp_$(BITS).o
 obj-$(CONFIG_PPC32)	+= strlen_32.o
 endif
+endif
 
 obj-$(CONFIG_PPC32)	+= div64.o copy_32.o crtsavres.o
 
diff --git a/arch/powerpc/lib/mem_64.S b/arch/powerpc/lib/mem_64.S
index 6fd06cd20faa..a55f2fac49b3 100644
--- a/arch/powerpc/lib/mem_64.S
+++ b/arch/powerpc/lib/mem_64.S
@@ -9,8 +9,9 @@
 #include <asm/errno.h>
 #include <asm/ppc_asm.h>
 #include <asm/kasan.h>
+#include <asm/kmsan.h>
 
-#ifndef CONFIG_KASAN
+#if !defined(CONFIG_KASAN) && !defined(CONFIG_KMSAN)
 _GLOBAL(__memset16)
 	rlwimi	r4,r4,16,0,15
 	/* fall through */
@@ -96,6 +97,7 @@ _GLOBAL_KASAN(memset)
 	blr
 EXPORT_SYMBOL(memset)
 EXPORT_SYMBOL_KASAN(memset)
+EXPORT_SYMBOL_KMSAN(memset)
 
 _GLOBAL_TOC_KASAN(memmove)
 	cmplw	0,r3,r4
@@ -140,3 +142,4 @@ _GLOBAL(backwards_memcpy)
 	b	1b
 EXPORT_SYMBOL(memmove)
 EXPORT_SYMBOL_KASAN(memmove)
+EXPORT_SYMBOL_KMSAN(memmove)
diff --git a/arch/powerpc/lib/memcpy_64.S b/arch/powerpc/lib/memcpy_64.S
index b5a67e20143f..1657861618cc 100644
--- a/arch/powerpc/lib/memcpy_64.S
+++ b/arch/powerpc/lib/memcpy_64.S
@@ -8,6 +8,7 @@
 #include <asm/asm-compat.h>
 #include <asm/feature-fixups.h>
 #include <asm/kasan.h>
+#include <asm/kmsan.h>
 
 #ifndef SELFTEST_CASE
 /* For big-endian, 0 == most CPUs, 1 == POWER6, 2 == Cell */
@@ -228,3 +229,4 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_LD_STD)
 #endif
 EXPORT_SYMBOL(memcpy)
 EXPORT_SYMBOL_KASAN(memcpy)
+EXPORT_SYMBOL_KMSAN(memcpy)
diff --git a/tools/testing/selftests/powerpc/copyloops/asm/kmsan.h b/tools/testing/selftests/powerpc/copyloops/asm/kmsan.h
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/tools/testing/selftests/powerpc/copyloops/linux/export.h b/tools/testing/selftests/powerpc/copyloops/linux/export.h
index e6b80d5fbd14..6379624bbf9b 100644
--- a/tools/testing/selftests/powerpc/copyloops/linux/export.h
+++ b/tools/testing/selftests/powerpc/copyloops/linux/export.h
@@ -2,3 +2,4 @@
 #define EXPORT_SYMBOL(x)
 #define EXPORT_SYMBOL_GPL(x)
 #define EXPORT_SYMBOL_KASAN(x)
+#define EXPORT_SYMBOL_KMSAN(x)
-- 
2.40.1