[PATCH] powerpc/kasan: require memintrinsic prefix support for KASAN

@@ -7,6 +7,10 @@ config CC_HAS_ELFV2
 config CC_HAS_PREFIXED
 	def_bool PPC64 && $(cc-option, -mcpu=power10 -mprefixed)
 
+config PPC_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
+	def_bool (CC_IS_CLANG && $(cc-option,-fsanitize=kernel-address -mllvm -asan-kernel-mem-intrinsic-prefix=1)) || \
+		 (CC_IS_GCC && $(cc-option,-fsanitize=kernel-address --param asan-kernel-mem-intrinsic-prefix=1))
+
 config CC_HAS_PCREL
 	# Clang has a bug (https://github.com/llvm/llvm-project/issues/62372)
 	# where pcrel code is not generated if -msoft-float, -mno-altivec, or

@@ -220,9 +224,9 @@ config PPC
 	select HAVE_ARCH_HUGE_VMAP		if PPC_RADIX_MMU || PPC_8xx
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_JUMP_LABEL_RELATIVE
-	select HAVE_ARCH_KASAN			if PPC32 && PAGE_SHIFT <= 14
-	select HAVE_ARCH_KASAN			if PPC_RADIX_MMU
-	select HAVE_ARCH_KASAN			if PPC_BOOK3E_64
+	select HAVE_ARCH_KASAN			if PPC32 && PAGE_SHIFT <= 14 && PPC_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
+	select HAVE_ARCH_KASAN			if PPC_RADIX_MMU && PPC_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
+	select HAVE_ARCH_KASAN			if PPC_BOOK3E_64 && PPC_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
 	select HAVE_ARCH_KASAN_VMALLOC		if HAVE_ARCH_KASAN
 	select HAVE_ARCH_KCSAN
 	select HAVE_ARCH_KFENCE			if ARCH_SUPPORTS_DEBUG_PAGEALLOC

@@ -2,20 +2,17 @@
 #ifndef __ASM_KASAN_H
 #define __ASM_KASAN_H
 
-#if defined(CONFIG_KASAN) && !defined(CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX)
-#define _GLOBAL_KASAN(fn)			\
-	_GLOBAL(fn);				\
-	_GLOBAL(__##fn)
-#define _GLOBAL_TOC_KASAN(fn)			\
-	_GLOBAL_TOC(fn);			\
-	_GLOBAL_TOC(__##fn)
-#define EXPORT_SYMBOL_KASAN(fn)			\
-	EXPORT_SYMBOL(__##fn)
-#else /* CONFIG_KASAN && !CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX */
+/*
+ * powerpc requires CC_HAS_KASAN_MEMINTRINSIC_PREFIX whenever KASAN is
+ * enabled (see PPC_CC_HAS_KASAN_MEMINTRINSIC_PREFIX in arch/powerpc/Kconfig),
+ * so the compiler always emits __asan_mem*() at instrumented call sites and
+ * bare mem*() inside __no_sanitize_address / noinstr code.  The old dual
+ * entry-point trick (_GLOBAL_KASAN emitting both memset and __memset) is
+ * therefore never needed.
+ */
 #define _GLOBAL_KASAN(fn)	_GLOBAL(fn)
 #define _GLOBAL_TOC_KASAN(fn)	_GLOBAL_TOC(fn)
 #define EXPORT_SYMBOL_KASAN(fn)
-#endif /* CONFIG_KASAN && !CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX */
 
 #ifndef __ASSEMBLER__
 

@@ -29,29 +29,14 @@ extern void * memchr(const void *,int,__kernel_size_t);
 void memcpy_flushcache(void *dest, const void *src, size_t size);
 
 #ifdef CONFIG_KASAN
-/* __mem variants are used by KASAN to implement instrumented meminstrinsics. */
-#ifdef CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
+/*
+ * powerpc requires CC_HAS_KASAN_MEMINTRINSIC_PREFIX whenever KASAN is
+ * enabled, so the compiler emits __asan_mem*() at instrumented sites.
+ * The raw mem* symbols are always safe to call directly.
+ */
 #define __memset memset
 #define __memcpy memcpy
 #define __memmove memmove
-#else /* CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX */
-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);
-#ifndef __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 /* !__SANITIZE_ADDRESS__ */
-#endif /* CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX */
 #endif /* CONFIG_KASAN */
 
 #ifdef CONFIG_PPC64

@@ -36,8 +36,8 @@ void __init set_cur_cpu_spec(struct cpu_spec *s)
 
 	t = PTRRELOC(t);
 	/*
-	 * use memcpy() instead of *t = *s so that GCC replaces it
-	 * by __memcpy() when KASAN is active
+	 * use memcpy() instead of *t = *s so that the compiler replaces it
+	 * by __asan_memcpy() when KASAN is active
 	 */
 	memcpy(t, s, sizeof(*t));
 

@@ -55,7 +55,7 @@ static struct cpu_spec * __init setup_cpu_spec(unsigned long offset,
 
 	/*
 	 * Copy everything, then do fixups. Use memcpy() instead of *t = *s
-	 * so that GCC replaces it by __memcpy() when KASAN is active
+	 * so that the compiler replaces it by __asan_memcpy() when KASAN is active
 	 */
 	memcpy(t, s, sizeof(*t));
 

@@ -1365,8 +1365,8 @@ static void __init prom_check_platform_support(void)
 	/*
 	 * First copy the architecture vec template
 	 *
-	 * use memcpy() instead of *vec = *vec_template so that GCC replaces it
-	 * by __memcpy() when KASAN is active
+	 * use memcpy() instead of *vec = *vec_template so that the compiler
+	 * replaces it by __asan_memcpy() when KASAN is active
 	 */
 	memcpy(&ibm_architecture_vec, &ibm_architecture_vec_template,
 	       sizeof(ibm_architecture_vec));