diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 2580e27e432874..b27ed9739eea58 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -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
diff --git a/arch/powerpc/include/asm/kasan.h b/arch/powerpc/include/asm/kasan.h
index a690e7da53c279..d62756b87ba4a4 100644
--- a/arch/powerpc/include/asm/kasan.h
+++ b/arch/powerpc/include/asm/kasan.h
@@ -2,20 +2,9 @@
 #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 */
 #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__
 
diff --git a/arch/powerpc/include/asm/string.h b/arch/powerpc/include/asm/string.h
index 1981bd4036b548..72b5c93a2b8486 100644
--- a/arch/powerpc/include/asm/string.h
+++ b/arch/powerpc/include/asm/string.h
@@ -29,29 +29,10 @@ 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
+/* Used by mm/kasan/shadow.c as raw backends to bypass KASAN checking. */
 #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
diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
index 6f6801da9dc1e2..233b5c650d1ebd 100644
--- a/arch/powerpc/kernel/cputable.c
+++ b/arch/powerpc/kernel/cputable.c
@@ -36,8 +36,12 @@ 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 because t is a PTRRELOC-adjusted
+	 * pointer and this code runs before the MMU mapping is established.
+	 * A struct assignment is a compiler-generated aggregate copy whose
+	 * implementation is not under our control in relocation-sensitive code;
+	 * memcpy() ensures the adjusted pointer is explicitly passed to the
+	 * copy routine.
 	 */
 	memcpy(t, s, sizeof(*t));
 
@@ -55,7 +59,11 @@ 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
+	 * because t is a PTRRELOC-adjusted pointer and this code runs before
+	 * the MMU mapping is established. A struct assignment is a
+	 * compiler-generated aggregate copy whose implementation is not under
+	 * our control in relocation-sensitive code; memcpy() ensures the
+	 * adjusted pointer is explicitly passed to the copy routine.
 	 */
 	memcpy(t, s, sizeof(*t));
 
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index eb9f556b0937e3..d6d7f1ede319d6 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -1363,10 +1363,12 @@ static void __init prom_check_platform_support(void)
 				       "ibm,arch-vec-5-platform-support");
 
 	/*
-	 * First copy the architecture vec template
-	 *
-	 * use memcpy() instead of *vec = *vec_template so that GCC replaces it
-	 * by __memcpy() when KASAN is active
+	 * First copy the architecture vec template. Use memcpy() instead of
+	 * a struct assignment because this code runs before the MMU mapping
+	 * is established. A struct assignment is a compiler-generated
+	 * aggregate copy whose implementation is not under our control in
+	 * relocation-sensitive code; memcpy() ensures the adjusted pointer
+	 * is explicitly passed to the copy routine.
 	 */
 	memcpy(&ibm_architecture_vec, &ibm_architecture_vec_template,
 	       sizeof(ibm_architecture_vec));