From 36be5cba99f6f9984a9a9f0454f95a38f4184d3e Mon Sep 17 00:00:00 2001
From: Marco Elver <elver@google.com>
Date: Fri, 24 Feb 2023 09:59:40 +0100
Subject: kasan: treat meminstrinsic as builtins in uninstrumented files

Where the compiler instruments meminstrinsics by generating calls to
__asan/__hwasan_ prefixed functions, let the compiler consider
memintrinsics as builtin again.

To do so, never override memset/memmove/memcpy if the compiler does the
correct instrumentation - even on !GENERIC_ENTRY architectures.

[elver@google.com: powerpc: don't rename memintrinsics if compiler adds prefixes]
  Link: https://lore.kernel.org/all/20230224085942.1791837-1-elver@google.com/ [1]
  Link: https://lkml.kernel.org/r/20230227094726.3833247-1-elver@google.com
Link: https://lkml.kernel.org/r/20230224085942.1791837-2-elver@google.com
Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
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: Kees Cook <keescook@chromium.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nicolas Schier <nicolas@fjasle.eu>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 lib/Kconfig.kasan | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'lib/Kconfig.kasan')

diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index be6ee6020290..fdca89c05745 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -49,6 +49,15 @@ menuconfig KASAN
 
 if KASAN
 
+config 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))
+	# Don't define it if we don't need it: compilation of the test uses
+	# this variable to decide how the compiler should treat builtins.
+	depends on !KASAN_HW_TAGS
+	help
+	  The compiler is able to prefix memintrinsics with __asan or __hwasan.
+
 choice
 	prompt "KASAN mode"
 	default KASAN_GENERIC
-- 
cgit