From: Andrey Konovalov <andreyknvl@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Dmitry Vyukov <dvyukov@google.com>,
Marco Elver <elver@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Will Deacon <will.deacon@arm.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Evgenii Stepanov <eugenis@google.com>,
Branislav Rankov <Branislav.Rankov@arm.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
kasan-dev <kasan-dev@googlegroups.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 07/11] kasan: add compiler barriers to KUNIT_EXPECT_KASAN_FAIL
Date: Tue, 12 Jan 2021 20:50:54 +0100 [thread overview]
Message-ID: <CAAeHK+yFw5YcR1jAYbE+PSLc0NowCv88mS8kJLspe_RkSjX37w@mail.gmail.com> (raw)
In-Reply-To: <CAG_fn=Uqp6dt5VGF8Dt6FeQzDgcEbVY8fs+5+wyMp2d1Z98sEw@mail.gmail.com>
On Tue, Jan 12, 2021 at 9:18 AM Alexander Potapenko <glider@google.com> wrote:
>
> On Tue, Jan 5, 2021 at 7:28 PM Andrey Konovalov <andreyknvl@google.com> wrote:
> >
> > It might not be obvious to the compiler that the expression must be
> > executed between writing and reading to fail_data. In this case, the
> > compiler might reorder or optimize away some of the accesses, and
> > the tests will fail.
>
> Have you seen this happen in practice?
Yes.
> Are these accesses to fail_data that are optimized (in which case we
> could make it volatile)?
Yes. AFAIU compiler doesn't expect expression to change fail_data
fields, no those accesses and checks are optimized away.
> Note that compiler barriers won't probably help against removing
> memory accesses, they only prevent reordering.
>
> > + barrier(); \
> > expression; \
> > + barrier(); \
>
> The need for barriers is not obvious to the reader, so a comment in
> the code clarifying that would be nice.
Will add a comment in v2, thanks!
next prev parent reply other threads:[~2021-01-12 19:51 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-05 18:27 [PATCH 00/11] kasan: HW_TAGS tests support and fixes Andrey Konovalov
2021-01-05 18:27 ` [PATCH 01/11] kasan: prefix exported functions with kasan_ Andrey Konovalov
2021-01-12 7:38 ` Alexander Potapenko
2021-01-12 11:19 ` Marco Elver
2021-01-05 18:27 ` [PATCH 02/11] kasan: clarify HW_TAGS impact on TBI Andrey Konovalov
2021-01-12 7:40 ` Alexander Potapenko
2021-01-12 11:38 ` Marco Elver
2021-01-05 18:27 ` [PATCH 03/11] kasan: clean up comments in tests Andrey Konovalov
2021-01-12 7:53 ` Alexander Potapenko
2021-01-12 17:55 ` Andrey Konovalov
2021-01-12 13:07 ` Marco Elver
2021-01-05 18:27 ` [PATCH 04/11] kasan: add match-all tag tests Andrey Konovalov
2021-01-12 8:04 ` Alexander Potapenko
2021-01-12 18:10 ` Andrey Konovalov
2021-01-12 13:17 ` Marco Elver
2021-01-12 18:11 ` Andrey Konovalov
2021-01-05 18:27 ` [PATCH 05/11] kasan, arm64: allow using KUnit tests with HW_TAGS mode Andrey Konovalov
2021-01-12 19:01 ` Catalin Marinas
2021-01-15 13:11 ` Andrey Konovalov
2021-01-15 15:04 ` Vincenzo Frascino
2021-01-05 18:27 ` [PATCH 06/11] kasan: rename CONFIG_TEST_KASAN_MODULE Andrey Konovalov
2021-01-12 8:09 ` Alexander Potapenko
2021-01-12 18:26 ` Andrey Konovalov
2021-01-12 13:33 ` Marco Elver
2021-01-12 18:28 ` Andrey Konovalov
2021-01-05 18:27 ` [PATCH 07/11] kasan: add compiler barriers to KUNIT_EXPECT_KASAN_FAIL Andrey Konovalov
2021-01-12 8:18 ` Alexander Potapenko
2021-01-12 19:50 ` Andrey Konovalov [this message]
2021-01-12 19:57 ` Andrey Konovalov
2021-01-12 13:34 ` Marco Elver
2021-01-05 18:27 ` [PATCH 08/11] kasan: adopt kmalloc_uaf2 test to HW_TAGS mode Andrey Konovalov
2021-01-12 8:25 ` Alexander Potapenko
2021-01-12 20:04 ` Andrey Konovalov
2021-01-12 13:39 ` Marco Elver
2021-01-12 20:05 ` Andrey Konovalov
2021-01-05 18:27 ` [PATCH 09/11] kasan: fix memory corruption in kasan_bitops_tags test Andrey Konovalov
2021-01-12 8:30 ` Alexander Potapenko
2021-01-12 20:06 ` Andrey Konovalov
2021-01-13 12:30 ` Alexander Potapenko
2021-01-12 13:55 ` Marco Elver
2021-01-05 18:27 ` [PATCH 10/11] kasan: fix bug detection via ksize for HW_TAGS mode Andrey Konovalov
2021-01-12 14:32 ` Marco Elver
2021-01-12 21:16 ` Andrey Konovalov
2021-01-12 22:54 ` Marco Elver
2021-01-05 18:27 ` [PATCH 11/11] kasan: add proper page allocator tests Andrey Konovalov
2021-01-12 8:57 ` Alexander Potapenko
2021-01-12 14:34 ` Marco Elver
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