[PATCH v9 02/11] powerpc: prepare string/mem functions for KASAN

[Christophe Leroy <christophe.leroy@c-s.fr>]

CONFIG_KASAN implements wrappers for memcpy() memmove() and memset()
Those wrappers are doing the verification then call respectively
__memcpy() __memmove() and __memset(). The arches are therefore
expected to rename their optimised functions that way.

For files on which KASAN is inhibited, #defines are used to allow
them to directly call optimised versions of the functions without
going through the KASAN wrappers.

See commit 393f203f5fd5 ("x86_64: kasan: add interceptors for
memset/memmove/memcpy functions") for details.

Other string / mem functions do not (yet) have kasan wrappers,
we therefore have to fallback to the generic versions when
KASAN is active, otherwise KASAN checks will be skipped.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/include/asm/kasan.h       | 15 +++++++++++++++
 arch/powerpc/include/asm/string.h      | 32 +++++++++++++++++++++++++++++---
 arch/powerpc/kernel/prom_init_check.sh | 10 +++++++++-
 arch/powerpc/lib/Makefile              | 11 ++++++++---
 arch/powerpc/lib/copy_32.S             | 15 +++++++++------
 arch/powerpc/lib/mem_64.S              | 11 +++++++----
 arch/powerpc/lib/memcpy_64.S           |  5 +++--
 7 files changed, 80 insertions(+), 19 deletions(-)
 create mode 100644 arch/powerpc/include/asm/kasan.h

diff --git a/arch/powerpc/include/asm/kasan.h b/arch/powerpc/include/asm/kasan.h
new file mode 100644
index 000000000000..c3161b8fc017
--- /dev/null
+++ b/arch/powerpc/include/asm/kasan.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_KASAN_H
+#define __ASM_KASAN_H
+
+#ifdef CONFIG_KASAN
+#define _GLOBAL_KASAN(fn)	.weak fn ; _GLOBAL(__##fn) ; _GLOBAL(fn)
+#define _GLOBAL_TOC_KASAN(fn)	.weak fn ; _GLOBAL_TOC(__##fn) ; _GLOBAL_TOC(fn)
+#define EXPORT_SYMBOL_KASAN(fn)	EXPORT_SYMBOL(__##fn) ; EXPORT_SYMBOL(fn)
+#else
+#define _GLOBAL_KASAN(fn)	_GLOBAL(fn)
+#define _GLOBAL_TOC_KASAN(fn)	_GLOBAL_TOC(fn)
+#define EXPORT_SYMBOL_KASAN(fn)	EXPORT_SYMBOL(fn)
+#endif
+
+#endif
diff --git a/arch/powerpc/include/asm/string.h b/arch/powerpc/include/asm/string.h
index 1647de15a31e..9bf6dffb4090 100644
--- a/arch/powerpc/include/asm/string.h
+++ b/arch/powerpc/include/asm/string.h
@@ -4,14 +4,17 @@
 
 #ifdef __KERNEL__
 
+#ifndef CONFIG_KASAN
 #define __HAVE_ARCH_STRNCPY
 #define __HAVE_ARCH_STRNCMP
+#define __HAVE_ARCH_MEMCHR
+#define __HAVE_ARCH_MEMCMP
+#define __HAVE_ARCH_MEMSET16
+#endif
+
 #define __HAVE_ARCH_MEMSET
 #define __HAVE_ARCH_MEMCPY
 #define __HAVE_ARCH_MEMMOVE
-#define __HAVE_ARCH_MEMCMP
-#define __HAVE_ARCH_MEMCHR
-#define __HAVE_ARCH_MEMSET16
 #define __HAVE_ARCH_MEMCPY_FLUSHCACHE
 
 extern char * strcpy(char *,const char *);
@@ -27,7 +30,27 @@ extern int memcmp(const void *,const void *,__kernel_size_t);
 extern void * memchr(const void *,int,__kernel_size_t);
 extern void * memcpy_flushcache(void *,const void *,__kernel_size_t);
 
+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);
+
+#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
+/*
+ * For files that are not instrumented (e.g. mm/slub.c) we
+ * should use not instrumented version of mem* functions.
+ */
+#define memcpy(dst, src, len) __memcpy(dst, src, len)
+#define memmove(dst, src, len) __memmove(dst, src, len)
+#define memset(s, c, n) __memset(s, c, n)
+
+#ifndef __NO_FORTIFY
+#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
+#endif
+
+#endif
+
 #ifdef CONFIG_PPC64
+#ifndef CONFIG_KASAN
 #define __HAVE_ARCH_MEMSET32
 #define __HAVE_ARCH_MEMSET64
 
@@ -49,8 +72,11 @@ static inline void *memset64(uint64_t *p, uint64_t v, __kernel_size_t n)
 {
 	return __memset64(p, v, n * 8);
 }
+#endif
 #else
+#ifndef CONFIG_KASAN
 #define __HAVE_ARCH_STRLEN
+#endif
 
 extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
 #endif
diff --git a/arch/powerpc/kernel/prom_init_check.sh b/arch/powerpc/kernel/prom_init_check.sh
index 667df97d2595..181fd10008ef 100644
--- a/arch/powerpc/kernel/prom_init_check.sh
+++ b/arch/powerpc/kernel/prom_init_check.sh
@@ -16,8 +16,16 @@
 # If you really need to reference something from prom_init.o add
 # it to the list below:
 
+grep "^CONFIG_KASAN=y$" .config >/dev/null
+if [ $? -eq 0 ]
+then
+	MEM_FUNCS="__memcpy __memset"
+else
+	MEM_FUNCS="memcpy memset"
+fi
+
 WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
-_end enter_prom memcpy memset reloc_offset __secondary_hold
+_end enter_prom $MEM_FUNCS reloc_offset __secondary_hold
 __secondary_hold_acknowledge __secondary_hold_spinloop __start
 strcmp strcpy strlcpy strlen strncmp strstr kstrtobool logo_linux_clut224
 reloc_got2 kernstart_addr memstart_addr linux_banner _stext
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 79396e184bca..47a4de434c22 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -8,9 +8,14 @@ ccflags-$(CONFIG_PPC64)	:= $(NO_MINIMAL_TOC)
 CFLAGS_REMOVE_code-patching.o = $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)
 
-obj-y += string.o alloc.o code-patching.o feature-fixups.o
+obj-y += alloc.o code-patching.o feature-fixups.o
 
-obj-$(CONFIG_PPC32)	+= div64.o copy_32.o crtsavres.o strlen_32.o
+ifndef CONFIG_KASAN
+obj-y	+=	string.o memcmp_$(BITS).o
+obj-$(CONFIG_PPC32)	+= strlen_32.o
+endif
+
+obj-$(CONFIG_PPC32)	+= div64.o copy_32.o crtsavres.o
 
 obj-$(CONFIG_FUNCTION_ERROR_INJECTION)	+= error-inject.o
 
@@ -34,7 +39,7 @@ obj64-$(CONFIG_KPROBES_SANITY_TEST)	+= test_emulate_step.o \
 					   test_emulate_step_exec_instr.o
 
 obj-y			+= checksum_$(BITS).o checksum_wrappers.o \
-			   string_$(BITS).o memcmp_$(BITS).o
+			   string_$(BITS).o
 
 obj-y			+= sstep.o ldstfp.o quad.o
 obj64-y			+= quad.o
diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index ba66846fe973..fc4fa7246200 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -14,6 +14,7 @@
 #include <asm/ppc_asm.h>
 #include <asm/export.h>
 #include <asm/code-patching-asm.h>
+#include <asm/kasan.h>
 
 #define COPY_16_BYTES		\
 	lwz	r7,4(r4);	\
@@ -68,6 +69,7 @@ CACHELINE_BYTES = L1_CACHE_BYTES
 LG_CACHELINE_BYTES = L1_CACHE_SHIFT
 CACHELINE_MASK = (L1_CACHE_BYTES-1)
 
+#ifndef CONFIG_KASAN
 _GLOBAL(memset16)
 	rlwinm.	r0 ,r5, 31, 1, 31
 	addi	r6, r3, -4
@@ -81,6 +83,7 @@ _GLOBAL(memset16)
 	sth	r4, 4(r6)
 	blr
 EXPORT_SYMBOL(memset16)
+#endif
 
 /*
  * Use dcbz on the complete cache lines in the destination
@@ -91,7 +94,7 @@ EXPORT_SYMBOL(memset16)
  * We therefore skip the optimised bloc that uses dcbz. This jump is
  * replaced by a nop once cache is active. This is done in machine_init()
  */
-_GLOBAL(memset)
+_GLOBAL_KASAN(memset)
 	cmplwi	0,r5,4
 	blt	7f
 
@@ -150,7 +153,7 @@ _GLOBAL(memset)
 9:	stbu	r4,1(r6)
 	bdnz	9b
 	blr
-EXPORT_SYMBOL(memset)
+EXPORT_SYMBOL_KASAN(memset)
 
 /*
  * This version uses dcbz on the complete cache lines in the
@@ -163,12 +166,12 @@ EXPORT_SYMBOL(memset)
  * We therefore jump to generic_memcpy which doesn't use dcbz. This jump is
  * replaced by a nop once cache is active. This is done in machine_init()
  */
-_GLOBAL(memmove)
+_GLOBAL_KASAN(memmove)
 	cmplw	0,r3,r4
 	bgt	backwards_memcpy
 	/* fall through */
 
-_GLOBAL(memcpy)
+_GLOBAL_KASAN(memcpy)
 1:	b	generic_memcpy
 	patch_site	1b, patch__memcpy_nocache
 
@@ -242,8 +245,8 @@ _GLOBAL(memcpy)
 	stbu	r0,1(r6)
 	bdnz	40b
 65:	blr
-EXPORT_SYMBOL(memcpy)
-EXPORT_SYMBOL(memmove)
+EXPORT_SYMBOL_KASAN(memcpy)
+EXPORT_SYMBOL_KASAN(memmove)
 
 generic_memcpy:
 	srwi.	r7,r5,3
diff --git a/arch/powerpc/lib/mem_64.S b/arch/powerpc/lib/mem_64.S
index 3c3be02f33b7..7cd6cf6822a2 100644
--- a/arch/powerpc/lib/mem_64.S
+++ b/arch/powerpc/lib/mem_64.S
@@ -12,7 +12,9 @@
 #include <asm/errno.h>
 #include <asm/ppc_asm.h>
 #include <asm/export.h>
+#include <asm/kasan.h>
 
+#ifndef CONFIG_KASAN
 _GLOBAL(__memset16)
 	rlwimi	r4,r4,16,0,15
 	/* fall through */
@@ -29,8 +31,9 @@ _GLOBAL(__memset64)
 EXPORT_SYMBOL(__memset16)
 EXPORT_SYMBOL(__memset32)
 EXPORT_SYMBOL(__memset64)
+#endif
 
-_GLOBAL(memset)
+_GLOBAL_KASAN(memset)
 	neg	r0,r3
 	rlwimi	r4,r4,8,16,23
 	andi.	r0,r0,7			/* # bytes to be 8-byte aligned */
@@ -95,9 +98,9 @@ _GLOBAL(memset)
 10:	bflr	31
 	stb	r4,0(r6)
 	blr
-EXPORT_SYMBOL(memset)
+EXPORT_SYMBOL_KASAN(memset)
 
-_GLOBAL_TOC(memmove)
+_GLOBAL_TOC_KASAN(memmove)
 	cmplw	0,r3,r4
 	bgt	backwards_memcpy
 	b	memcpy
@@ -138,4 +141,4 @@ _GLOBAL(backwards_memcpy)
 	beq	2b
 	mtctr	r7
 	b	1b
-EXPORT_SYMBOL(memmove)
+EXPORT_SYMBOL_KASAN(memmove)
diff --git a/arch/powerpc/lib/memcpy_64.S b/arch/powerpc/lib/memcpy_64.S
index 273ea67e60a1..862b515b8868 100644
--- a/arch/powerpc/lib/memcpy_64.S
+++ b/arch/powerpc/lib/memcpy_64.S
@@ -11,6 +11,7 @@
 #include <asm/export.h>
 #include <asm/asm-compat.h>
 #include <asm/feature-fixups.h>
+#include <asm/kasan.h>
 
 #ifndef SELFTEST_CASE
 /* For big-endian, 0 == most CPUs, 1 == POWER6, 2 == Cell */
@@ -18,7 +19,7 @@
 #endif
 
 	.align	7
-_GLOBAL_TOC(memcpy)
+_GLOBAL_TOC_KASAN(memcpy)
 BEGIN_FTR_SECTION
 #ifdef __LITTLE_ENDIAN__
 	cmpdi	cr7,r5,0
@@ -229,4 +230,4 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_LD_STD)
 4:	ld	r3,-STACKFRAMESIZE+STK_REG(R31)(r1)	/* return dest pointer */
 	blr
 #endif
-EXPORT_SYMBOL(memcpy)
+EXPORT_SYMBOL_KASAN(memcpy)
-- 
2.13.3