From: Arnd Bergmann <arnd@arndb.de>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Vegard Nossum <vegard.nossum@oracle.com>,
Dmitry Vyukov <dvyukov@google.com>,
Linux Memory Management List <linux-mm@kvack.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Christoph Hellwig <hch@lst.de>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Eric Dumazet <edumazet@google.com>,
Eric Van Hensbergen <ericvh@gmail.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Harry Wentland <harry.wentland@amd.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Ingo Molnar <mingo@elte.hu>, Jens Axboe <axboe@kernel.dk>,
"Martin K . Petersen" <martin.petersen@oracle.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Michal Simek <monstr@monstr.eu>, Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Takashi Iwai <tiwai@suse.com>, "Theodore Ts'o" <tytso@mit.edu>,
Thomas Gleixner <tglx@linutronix.de>,
Wolfram Sang <wsa@the-dreams.de>,
Vasily Gorbik <gor@linux.ibm.com>,
Ilya Leoshkevich <iii@linux.ibm.com>,
Mark Rutland <mark.rutland@arm.com>,
Matthew Wilcox <willy@infradead.org>,
Randy Dunlap <rdunlap@infradead.org>,
Andrey Konovalov <andreyknvl@google.com>,
Marco Elver <elver@google.com>,
Nick Desaulniers <ndesaulniers@google.com>,
clang-built-linux <clang-built-linux@googlegroups.com>
Subject: Re: [PATCH RFC v2 02/25] stackdepot: prevent Clang from optimizing away stackdepot_memcmp()
Date: Thu, 7 Nov 2019 11:00:19 +0100 [thread overview]
Message-ID: <CAK8P3a0pSy_dwg8h8vTK-yoa1W1OxLiisnBe9E_tDBfJY9E1qQ@mail.gmail.com> (raw)
In-Reply-To: <47fdac13-fa2c-2acd-2480-5e6d4db208f8@virtuozzo.com>
On Thu, Nov 7, 2019 at 10:46 AM Andrey Ryabinin <aryabinin@virtuozzo.com> wrote:
> On 11/7/19 12:22 PM, Alexander Potapenko wrote:
> > On Thu, Nov 7, 2019 at 10:04 AM Arnd Bergmann <arnd@arndb.de> wrote:
> >> On Thu, Nov 7, 2019 at 7:08 AM Sergey Senozhatsky
> >> <sergey.senozhatsky.work@gmail.com> wrote:
> >> The normal way to do a volatile access would be
> >> READ_ONCE()/WRITE_ONCE(), but that seems stronger than
> >> the barrier() here. I'd just stick to adding a barrier.
> > I actually like the READ_ONCE idea more, as READ_ONCE is really a
> > documented way to prevent the compiler from merging reads, which is
> > what we want here.
>
> I would rather go with -fno-builtin-bcmp or maybe even -fno-builtin if that works.
The commit message for 5f074f3e192f ("lib/string.c: implement a basic bcmp")
mentions that -fno-builtin-bcmp did not work for LTO when the global bcmp()
help was added. I don't know whether the same applies here, but my guess is
that it's the same issue.
Arnd
next prev parent reply other threads:[~2019-11-07 10:00 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-30 14:22 [PATCH RFC v2 00/25] Add KernelMemorySanitizer infrastructure glider
2019-10-30 14:22 ` [PATCH RFC v2 01/25] stackdepot: check depot_index before accessing the stack slab glider
2019-10-30 14:22 ` [PATCH RFC v2 02/25] stackdepot: prevent Clang from optimizing away stackdepot_memcmp() glider
2019-11-01 5:50 ` Sergey Senozhatsky
2019-11-06 11:43 ` Alexander Potapenko
2019-11-07 6:08 ` Sergey Senozhatsky
2019-11-07 9:04 ` Arnd Bergmann
2019-11-07 9:22 ` Alexander Potapenko
2019-11-07 9:28 ` Arnd Bergmann
2019-11-07 9:43 ` Alexander Potapenko
[not found] ` <47fdac13-fa2c-2acd-2480-5e6d4db208f8@virtuozzo.com>
2019-11-07 10:00 ` Arnd Bergmann [this message]
[not found] ` <6875c6e6-2f1f-f8e6-e5d7-d451c48397ff@virtuozzo.com>
2019-11-07 10:30 ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 03/25] kasan: stackdepot: move filter_irq_stacks() to stackdepot.c glider
2019-10-30 14:22 ` [PATCH RFC v2 04/25] stackdepot: reserve 5 extra bits in depot_stack_handle_t glider
2019-10-30 14:22 ` [PATCH RFC v2 05/25] kmsan: add ReST documentation glider
2019-10-30 14:22 ` [PATCH RFC v2 06/25] kmsan: gfp: introduce __GFP_NO_KMSAN_SHADOW glider
2019-10-30 14:22 ` [PATCH RFC v2 07/25] kmsan: introduce __no_sanitize_memory and __SANITIZE_MEMORY__ glider
2019-10-30 15:50 ` Andrey Konovalov
2019-11-01 12:52 ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 08/25] kmsan: reduce vmalloc space glider
2019-10-30 14:22 ` [PATCH RFC v2 09/25] kmsan: add KMSAN runtime glider
2019-11-08 12:08 ` Dmitry Vyukov
2019-11-08 12:17 ` Dmitry Vyukov
2019-11-21 12:06 ` Alexander Potapenko
2019-11-13 8:13 ` Wolfram Sang
2019-11-21 12:01 ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 10/25] kmsan: define READ_ONCE_NOCHECK() glider
2019-11-05 14:21 ` Mark Rutland
2019-11-21 12:08 ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 11/25] kmsan: x86: sync metadata pages on page fault glider
2019-10-30 14:22 ` [PATCH RFC v2 12/25] kmsan: add tests for KMSAN glider
2019-10-30 14:22 ` [PATCH RFC v2 13/25] kmsan: make READ_ONCE_TASK_STACK() return initialized values glider
2019-10-30 14:22 ` [PATCH RFC v2 14/25] kmsan: Kconfig changes to disable options incompatible with KMSAN glider
2019-10-30 14:34 ` Qian Cai
2019-10-30 14:34 ` Christoph Hellwig
2019-10-30 14:22 ` [PATCH RFC v2 15/25] kmsan: Changing existing files to enable KMSAN builds glider
2019-10-30 14:36 ` Christoph Hellwig
2019-10-30 14:22 ` [PATCH RFC v2 16/25] kmsan: disable KMSAN instrumentation for certain kernel parts glider
2019-10-30 14:22 ` [PATCH RFC v2 17/25] kmsan: mm: call KMSAN hooks from SLUB code glider
2019-10-30 16:07 ` Andrey Konovalov
2019-10-30 14:22 ` [PATCH RFC v2 18/25] kmsan: call KMSAN hooks where needed glider
2019-10-31 11:49 ` Petr Mladek
2019-11-01 8:26 ` Sergey Senozhatsky
2019-11-05 14:12 ` Alexander Potapenko
2019-11-06 9:04 ` Petr Mladek
2019-11-06 9:07 ` Sergey Senozhatsky
2019-10-30 14:22 ` [PATCH RFC v2 19/25] kmsan: disable instrumentation of certain functions glider
2019-10-30 14:22 ` [PATCH RFC v2 20/25] kmsan: unpoison |tlb| in arch_tlb_gather_mmu() glider
2019-10-30 14:22 ` [PATCH RFC v2 21/25] kmsan: use __msan_memcpy() where possible glider
2019-10-30 14:22 ` [PATCH RFC v2 22/25] kmsan: unpoisoning buffers from devices etc glider
2019-10-30 14:38 ` Christoph Hellwig
2019-11-05 15:02 ` Alexander Potapenko
2019-11-07 13:00 ` Alexander Potapenko
2019-11-13 11:07 ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 23/25] kmsan: hooks for copy_to_user() and friends glider
2019-10-30 14:22 ` [PATCH RFC v2 24/25] kmsan: disable strscpy() optimization under KMSAN glider
2019-10-30 14:22 ` [PATCH RFC v2 25/25] net: kasan: kmsan: support CONFIG_GENERIC_CSUM on x86, enable it for KASAN/KMSAN glider
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