From: Peter Zijlstra <peterz@infradead.org>
To: "Christoph Müllner" <christophm30@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Guo Ren <guoren@kernel.org>,
linux-riscv <linux-riscv@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-csky@vger.kernel.org,
linux-arch <linux-arch@vger.kernel.org>,
Guo Ren <guoren@linux.alibaba.com>, Will Deacon <will@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Waiman Long <longman@redhat.com>,
Arnd Bergmann <arnd@arndb.de>, Anup Patel <anup@brainfault.org>
Subject: Re: [PATCH v4 3/4] locking/qspinlock: Add ARCH_USE_QUEUED_SPINLOCKS_XCHG32
Date: Wed, 7 Apr 2021 18:44:34 +0200 [thread overview]
Message-ID: <YG3hcg32xw/D03P2@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <YG3U677P9QKqFGMY@hirez.programming.kicks-ass.net>
On Wed, Apr 07, 2021 at 05:51:07PM +0200, Peter Zijlstra wrote:
> On Wed, Apr 07, 2021 at 04:29:12PM +0200, Christoph Müllner wrote:
> > Further, it is not the case that RISC-V has no guarantees at all.
> > It just does not provide a forward progress guarantee for a
> > synchronization implementation,
> > that writes in an endless loop to a memory location while trying to
> > complete an LL/SC
> > loop on the same memory location at the same time.
>
> Userspace can DoS the kernel that way, see futex.
The longer answer is that this means you cannot share locks (or any
atomic really) across a trust boundary, which is of course exactly what
futex does.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: "Christoph Müllner" <christophm30@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Guo Ren <guoren@kernel.org>,
linux-riscv <linux-riscv@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-csky@vger.kernel.org,
linux-arch <linux-arch@vger.kernel.org>,
Guo Ren <guoren@linux.alibaba.com>, Will Deacon <will@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Waiman Long <longman@redhat.com>,
Arnd Bergmann <arnd@arndb.de>, Anup Patel <anup@brainfault.org>
Subject: Re: [PATCH v4 3/4] locking/qspinlock: Add ARCH_USE_QUEUED_SPINLOCKS_XCHG32
Date: Wed, 7 Apr 2021 18:44:34 +0200 [thread overview]
Message-ID: <YG3hcg32xw/D03P2@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <YG3U677P9QKqFGMY@hirez.programming.kicks-ass.net>
On Wed, Apr 07, 2021 at 05:51:07PM +0200, Peter Zijlstra wrote:
> On Wed, Apr 07, 2021 at 04:29:12PM +0200, Christoph Müllner wrote:
> > Further, it is not the case that RISC-V has no guarantees at all.
> > It just does not provide a forward progress guarantee for a
> > synchronization implementation,
> > that writes in an endless loop to a memory location while trying to
> > complete an LL/SC
> > loop on the same memory location at the same time.
>
> Userspace can DoS the kernel that way, see futex.
The longer answer is that this means you cannot share locks (or any
atomic really) across a trust boundary, which is of course exactly what
futex does.
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2021-04-07 16:45 UTC|newest]
Thread overview: 126+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-27 18:06 [PATCH v4 0/4] riscv: Add qspinlock/qrwlock guoren
2021-03-27 18:06 ` guoren
2021-03-27 18:06 ` [PATCH v4 1/4] riscv: cmpxchg.h: Cleanup unused code guoren
2021-03-27 18:06 ` guoren
2021-03-27 18:06 ` [PATCH v4 2/4] riscv: cmpxchg.h: Merge macros guoren
2021-03-27 18:06 ` guoren
2021-03-27 21:25 ` Arnd Bergmann
2021-03-27 21:25 ` Arnd Bergmann
2021-03-28 1:50 ` Guo Ren
2021-03-28 1:50 ` Guo Ren
2021-03-27 18:06 ` [PATCH v4 3/4] locking/qspinlock: Add ARCH_USE_QUEUED_SPINLOCKS_XCHG32 guoren
2021-03-27 18:06 ` guoren
2021-03-27 18:43 ` Waiman Long
2021-03-27 18:43 ` Waiman Long
2021-03-28 1:48 ` Guo Ren
2021-03-28 1:48 ` Guo Ren
2021-03-29 7:50 ` Peter Zijlstra
2021-03-29 7:50 ` Peter Zijlstra
2021-03-29 9:41 ` Arnd Bergmann
2021-03-29 9:41 ` Arnd Bergmann
2021-03-29 11:16 ` Peter Zijlstra
2021-03-29 11:16 ` Peter Zijlstra
2021-03-29 11:29 ` Peter Zijlstra
2021-03-29 11:29 ` Peter Zijlstra
2021-03-29 12:52 ` Guo Ren
2021-03-29 12:52 ` Guo Ren
2021-03-29 13:56 ` Arnd Bergmann
2021-03-29 13:56 ` Arnd Bergmann
2021-03-30 2:26 ` Guo Ren
2021-03-30 2:26 ` Guo Ren
2021-03-30 5:51 ` Anup Patel
2021-03-30 5:51 ` Anup Patel
2021-03-30 6:26 ` Guo Ren
2021-03-30 6:26 ` Guo Ren
2021-03-30 7:11 ` Arnd Bergmann
2021-03-30 7:11 ` Arnd Bergmann
2021-03-31 4:18 ` Guo Ren
2021-03-31 4:18 ` Guo Ren
2021-03-31 5:33 ` Paul Campbell
2021-03-31 5:33 ` Paul Campbell
2021-04-05 16:12 ` Guo Ren
2021-04-05 16:12 ` Guo Ren
2021-03-31 6:44 ` Guo Ren
2021-03-31 6:44 ` Guo Ren
2021-03-31 7:12 ` Arnd Bergmann
2021-03-31 7:12 ` Arnd Bergmann
2021-03-29 11:19 ` Guo Ren
2021-03-29 11:19 ` Guo Ren
2021-03-29 11:26 ` Peter Zijlstra
2021-03-29 11:26 ` Peter Zijlstra
2021-03-29 12:01 ` Guo Ren
2021-03-29 12:01 ` Guo Ren
2021-03-29 12:49 ` Peter Zijlstra
2021-03-29 12:49 ` Peter Zijlstra
2021-03-30 3:13 ` Guo Ren
2021-03-30 3:13 ` Guo Ren
2021-03-30 4:54 ` Anup Patel
2021-03-30 4:54 ` Anup Patel
2021-03-30 6:27 ` Guo Ren
2021-03-30 6:27 ` Guo Ren
2021-03-30 8:31 ` David Laight
2021-03-30 8:31 ` David Laight
2021-03-30 14:09 ` Waiman Long
2021-03-30 14:09 ` Waiman Long
2021-03-31 14:47 ` Guo Ren
2021-03-31 14:47 ` Guo Ren
2021-04-05 16:45 ` Guo Ren
2021-04-05 16:45 ` Guo Ren
2021-03-30 16:08 ` Peter Zijlstra
2021-03-30 16:08 ` Peter Zijlstra
2021-03-30 22:35 ` Stafford Horne
2021-03-30 22:35 ` Stafford Horne
2021-03-31 7:23 ` Arnd Bergmann
2021-03-31 7:23 ` Arnd Bergmann
2021-03-31 12:31 ` Stafford Horne
2021-03-31 12:31 ` Stafford Horne
2021-03-31 15:10 ` Guo Ren
2021-03-31 15:10 ` Guo Ren
2021-04-06 8:51 ` Stafford Horne
2021-04-06 8:51 ` Stafford Horne
2021-04-06 3:50 ` Guo Ren
2021-04-06 3:50 ` Guo Ren
2021-04-06 8:56 ` Stafford Horne
2021-04-06 8:56 ` Stafford Horne
2021-04-07 8:42 ` Arnd Bergmann
2021-04-07 8:42 ` Arnd Bergmann
2021-04-07 11:36 ` Peter Zijlstra
2021-04-07 11:36 ` Peter Zijlstra
2021-04-07 11:57 ` Arnd Bergmann
2021-04-07 11:57 ` Arnd Bergmann
2021-04-07 12:02 ` Peter Zijlstra
2021-04-07 12:02 ` Peter Zijlstra
2021-04-05 16:40 ` Guo Ren
2021-04-05 16:40 ` Guo Ren
2021-03-31 15:22 ` Guo Ren
2021-03-31 15:22 ` Guo Ren
2021-04-06 7:15 ` Peter Zijlstra
2021-04-06 7:15 ` Peter Zijlstra
2021-04-07 9:42 ` Christoph Hellwig
2021-04-07 9:42 ` Christoph Hellwig
2021-04-07 14:29 ` Christoph Müllner
2021-04-07 14:29 ` Christoph Müllner
2021-04-07 14:34 ` Christoph Hellwig
2021-04-07 14:34 ` Christoph Hellwig
2021-04-07 15:51 ` Peter Zijlstra
2021-04-07 15:51 ` Peter Zijlstra
2021-04-07 16:44 ` Peter Zijlstra [this message]
2021-04-07 16:44 ` Peter Zijlstra
2021-04-07 15:52 ` Peter Zijlstra
2021-04-07 15:52 ` Peter Zijlstra
2021-04-07 16:54 ` Peter Zijlstra
2021-04-07 16:54 ` Peter Zijlstra
2021-04-07 16:00 ` Peter Zijlstra
2021-04-07 16:00 ` Peter Zijlstra
2021-04-07 19:50 ` Christoph Müllner
2021-04-07 19:50 ` Christoph Müllner
2021-04-06 17:24 ` Boqun Feng
2021-04-06 17:24 ` Boqun Feng
2021-04-07 9:26 ` Peter Zijlstra
2021-04-07 9:26 ` Peter Zijlstra
2021-03-29 12:13 ` Anup Patel
2021-03-29 12:13 ` Anup Patel
2021-03-29 12:54 ` Peter Zijlstra
2021-03-29 12:54 ` Peter Zijlstra
2021-03-27 18:06 ` [PATCH v4 4/4] riscv: Convert custom spinlock/rwlock to generic qspinlock/qrwlock guoren
2021-03-27 18:06 ` guoren
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YG3hcg32xw/D03P2@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=anup@brainfault.org \
--cc=arnd@arndb.de \
--cc=christophm30@gmail.com \
--cc=guoren@kernel.org \
--cc=guoren@linux.alibaba.com \
--cc=hch@infradead.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-csky@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=longman@redhat.com \
--cc=mingo@redhat.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.