From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 118/166] lib/stackdepot.c: build with -fno-builtin Date: Mon, 06 Apr 2020 20:10:19 -0700 Message-ID: <20200407031019.GPp46WoMb%akpm@linux-foundation.org> References: <20200406200254.a69ebd9e08c4074e41ddebaf@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:55764 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726591AbgDGDKU (ORCPT ); Mon, 6 Apr 2020 23:10:20 -0400 In-Reply-To: <20200406200254.a69ebd9e08c4074e41ddebaf@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, andreyknvl@google.com, arnd@arndb.de, aryabinin@virtuozzo.com, dvyukov@google.com, elver@google.com, glider@google.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, sergey.senozhatsky@gmail.com, torvalds@linux-foundation.org, vegard.nossum@oracle.com From: Alexander Potapenko Subject: lib/stackdepot.c: build with -fno-builtin Clang may replace stackdepot_memcmp() with a call to instrumented bcmp(), which is exactly what we wanted to avoid creating stackdepot_memcmp(). Building the file with -fno-builtin prevents such optimizations. This patch has been previously mailed as part of KMSAN RFC patch series. Link: http://lkml.kernel.org/r/20200220141916.55455-2-glider@google.com Signed-off-by: Alexander Potapenko Cc: Vegard Nossum Cc: Dmitry Vyukov Cc: Marco Elver Cc: Andrey Konovalov Cc: Sergey Senozhatsky Cc: Arnd Bergmann Cc: Andrey Ryabinin Signed-off-by: Andrew Morton --- lib/Makefile | 4 ++++ 1 file changed, 4 insertions(+) --- a/lib/Makefile~stackdepot-build-with-fno-builtin +++ a/lib/Makefile @@ -223,6 +223,10 @@ obj-$(CONFIG_MEMREGION) += memregion.o obj-$(CONFIG_STMP_DEVICE) += stmp_device.o obj-$(CONFIG_IRQ_POLL) += irq_poll.o +# stackdepot.c should not be instrumented or call instrumented functions. +# Prevent the compiler from calling builtins like memcmp() or bcmp() from this +# file. +CFLAGS_stackdepot.o += -fno-builtin obj-$(CONFIG_STACKDEPOT) += stackdepot.o KASAN_SANITIZE_stackdepot.o := n KCOV_INSTRUMENT_stackdepot.o := n _