kasan: emit different calls for instrumentable memintrinsics

Clang 15 provides an option to prefix memcpy/memset/memmove calls with
__asan_/__hwasan_ in instrumented functions:
https://reviews.llvm.org/D122724

GCC will add support in future:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108777

Use it to regain KASAN instrumentation of memcpy/memset/memmove on
architectures that require noinstr to be really free from instrumented
mem*() functions (all GENERIC_ENTRY architectures).

Link: https://lkml.kernel.org/r/20230224085942.1791837-1-elver@google.com
Fixes: 69d4c0d321 ("entry, kasan, x86: Disallow overriding mem*() functions")
Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: kasan-dev@googlegroups.com
Cc: Kees Cook <keescook@chromium.org>
Cc: Linux Kernel Functional Testing <lkft@linaro.org>
Cc: Nathan Chancellor <nathan@kernel.org> # build only
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nicolas Schier <nicolas@fjasle.eu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/kasan/kasan.h

@@ -666,4 +666,8 @@ void __hwasan_storeN_noabort(unsigned long addr, size_t size);
 
 void __hwasan_tag_memory(unsigned long addr, u8 tag, unsigned long size);
 
+void *__hwasan_memset(void *addr, int c, size_t len);
+void *__hwasan_memmove(void *dest, const void *src, size_t len);
+void *__hwasan_memcpy(void *dest, const void *src, size_t len);
+
 #endif /* __MM_KASAN_KASAN_H */

mm/kasan/shadow.c

@@ -107,6 +107,17 @@ void *__asan_memcpy(void *dest, const void *src, size_t len)
 }
 EXPORT_SYMBOL(__asan_memcpy);
 
+#ifdef CONFIG_KASAN_SW_TAGS
+void *__hwasan_memset(void *addr, int c, size_t len) __alias(__asan_memset);
+EXPORT_SYMBOL(__hwasan_memset);
+#ifdef __HAVE_ARCH_MEMMOVE
+void *__hwasan_memmove(void *dest, const void *src, size_t len) __alias(__asan_memmove);
+EXPORT_SYMBOL(__hwasan_memmove);
+#endif
+void *__hwasan_memcpy(void *dest, const void *src, size_t len) __alias(__asan_memcpy);
+EXPORT_SYMBOL(__hwasan_memcpy);
+#endif
+
 void kasan_poison(const void *addr, size_t size, u8 value, bool init)
 {
 	void *shadow_start, *shadow_end;

scripts/Makefile.kasan

@@ -38,6 +38,11 @@ endif
 
 CFLAGS_KASAN += $(call cc-param,asan-stack=$(stack_enable))
 
+# Instrument memcpy/memset/memmove calls by using instrumented __asan_mem*()
+# instead. With compilers that don't support this option, compiler-inserted
+# memintrinsics won't be checked by KASAN on GENERIC_ENTRY architectures.
+CFLAGS_KASAN += $(call cc-param,asan-kernel-mem-intrinsic-prefix=1)
+
 endif # CONFIG_KASAN_GENERIC
 
 ifdef CONFIG_KASAN_SW_TAGS
@@ -54,6 +59,9 @@ CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
 		$(call cc-param,hwasan-inline-all-checks=0) \
 		$(instrumentation_flags)
 
+# Instrument memcpy/memset/memmove calls by using instrumented __hwasan_mem*().
+CFLAGS_KASAN += $(call cc-param,hwasan-kernel-mem-intrinsic-prefix=1)
+
 endif # CONFIG_KASAN_SW_TAGS
 
 export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE