From: Peter Zijlstra <peterz@infradead.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Piotr Figiel <figiel@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
paulmck <paulmck@kernel.org>, Boqun Feng <boqun.feng@gmail.com>,
Oleg Nesterov <oleg@redhat.com>,
"Dmitry V. Levin" <ldv@altlinux.org>,
Florian Weimer <fweimer@redhat.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Andrei Vagin <avagin@gmail.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Peter Oskolkov <posk@google.com>,
Kamil Yurtsever <kyurtsever@google.com>,
Chris Kennelly <ckennelly@google.com>,
Paul Turner <pjt@google.com>, emmir <emmir@google.com>,
linux-man <linux-man@vger.kernel.org>,
linux-api <linux-api@vger.kernel.org>
Subject: Re: [PATCH v2] ptrace: add PTRACE_GET_RSEQ_CONFIGURATION request
Date: Thu, 11 Mar 2021 17:51:45 +0100 [thread overview]
Message-ID: <YEpKoa9PgjffO7Q5@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1173189328.5477.1615474316906.JavaMail.zimbra@efficios.com>
On Thu, Mar 11, 2021 at 09:51:56AM -0500, Mathieu Desnoyers wrote:
>
>
> ----- On Feb 26, 2021, at 8:51 AM, Piotr Figiel figiel@google.com wrote:
>
> > For userspace checkpoint and restore (C/R) a way of getting process state
> > containing RSEQ configuration is needed.
> >
> > There are two ways this information is going to be used:
> > - to re-enable RSEQ for threads which had it enabled before C/R
> > - to detect if a thread was in a critical section during C/R
> >
> > Since C/R preserves TLS memory and addresses RSEQ ABI will be restored
> > using the address registered before C/R.
> >
> > Detection whether the thread is in a critical section during C/R is needed
> > to enforce behavior of RSEQ abort during C/R. Attaching with ptrace()
> > before registers are dumped itself doesn't cause RSEQ abort.
> > Restoring the instruction pointer within the critical section is
> > problematic because rseq_cs may get cleared before the control is passed
> > to the migrated application code leading to RSEQ invariants not being
> > preserved. C/R code will use RSEQ ABI address to find the abort handler
> > to which the instruction pointer needs to be set.
> >
> > To achieve above goals expose the RSEQ ABI address and the signature value
> > with the new ptrace request PTRACE_GET_RSEQ_CONFIGURATION.
> >
> > This new ptrace request can also be used by debuggers so they are aware
> > of stops within restartable sequences in progress.
> >
> > Signed-off-by: Piotr Figiel <figiel@google.com>
> > Reviewed-by: Michal Miroslaw <emmir@google.com>
>
> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
How do we route this? Do I stick this in tip/sched/core as being an rseq
patch?
next prev parent reply other threads:[~2021-03-11 16:53 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 13:51 [PATCH v2] ptrace: add PTRACE_GET_RSEQ_CONFIGURATION request Piotr Figiel
2021-02-26 15:32 ` Mathieu Desnoyers
2021-02-26 16:04 ` Michał Mirosław
2021-02-26 16:41 ` Mathieu Desnoyers
2021-02-26 16:06 ` Piotr Figiel
2021-03-03 18:55 ` Mathieu Desnoyers
2021-03-03 17:10 ` Florian Weimer
2021-03-10 18:50 ` Oleg Nesterov
2021-03-11 14:51 ` Mathieu Desnoyers
2021-03-11 16:51 ` Peter Zijlstra [this message]
2021-03-11 17:24 ` Mathieu Desnoyers
2021-03-17 13:13 ` [tip: sched/core] rseq, ptrace: Add " tip-bot2 for Piotr Figiel
2021-03-17 15:19 ` tip-bot2 for Piotr Figiel
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