From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io1-f72.google.com (mail-io1-f72.google.com [209.85.166.72]) by kanga.kvack.org (Postfix) with ESMTP id 603728E004D for ; Tue, 11 Dec 2018 08:45:03 -0500 (EST) Received: by mail-io1-f72.google.com with SMTP id r65so14072840iod.12 for ; Tue, 11 Dec 2018 05:45:03 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id y7sor7003186ioa.135.2018.12.11.05.45.02 for (Google Transport Security); Tue, 11 Dec 2018 05:45:02 -0800 (PST) MIME-Version: 1.0 References: <20181211133453.2835077-1-arnd@arndb.de> In-Reply-To: <20181211133453.2835077-1-arnd@arndb.de> From: Dmitry Vyukov Date: Tue, 11 Dec 2018 14:44:50 +0100 Message-ID: Subject: Re: [PATCH] kasan: fix kasan_check_read/write definitions Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Arnd Bergmann Cc: Andrew Morton , Andrey Ryabinin , anders.roxell@linaro.org, Ard Biesheuvel , Will Deacon , Mark Rutland , Alexander Potapenko , Andrey Konovalov , Stephen Rothwell , kasan-dev , LKML , Linux-MM On Tue, Dec 11, 2018 at 2:35 PM Arnd Bergmann wrote: > > Building little-endian allmodconfig kernels on arm64 started failing > with the generated atomic.h implementation, since we now try to call > kasan helpers from the EFI stub: > > aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set': > include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write' > > I suspect that we get similar problems in other files that explicitly > disable KASAN for some reason but call atomic_t based helper functions. > > We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro > that the compiler sets instead of checking CONFIG_KASAN, but this in turn > requires a small hack in mm/kasan/common.c so we do see the extern > declaration there instead of the inline function. Alexander, I think you are doing a similar thing for similar reasons in KMSAN patch (see KMSAN_CHECK_ATOMIC_PARAMS): https://github.com/google/kmsan/commit/17ebbfe19624c84adf79b0e5a74fd258c49ff12b Namely, non-KMSAN-instrumented files must not get KMSAN callbacks from atomics too. Arnd patch does it the other way around: non-instrumented files need to opt-in instead of opt-out. Let's settle on a common way to do this, so that we can use it consistently across all tools. > Fixes: b1864b828644 ("locking/atomics: build atomic headers as required") > Reported-by: Anders Roxell > Signed-off-by: Arnd Bergmann > --- > include/linux/kasan-checks.h | 2 +- > mm/kasan/common.c | 2 ++ > 2 files changed, 3 insertions(+), 1 deletion(-) > > diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h > index d314150658a4..a61dc075e2ce 100644 > --- a/include/linux/kasan-checks.h > +++ b/include/linux/kasan-checks.h > @@ -2,7 +2,7 @@ > #ifndef _LINUX_KASAN_CHECKS_H > #define _LINUX_KASAN_CHECKS_H > > -#ifdef CONFIG_KASAN > +#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL) > void kasan_check_read(const volatile void *p, unsigned int size); > void kasan_check_write(const volatile void *p, unsigned int size); > #else > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index 03d5d1374ca7..51a7932c33a3 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -14,6 +14,8 @@ > * > */ > > +#define __KASAN_INTERNAL > + > #include > #include > #include > -- > 2.20.0 >