From: Will Deacon <will@kernel.org>
To: Keno Fischer <keno@juliacomputing.com>
Cc: linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
Oleg Nesterov <oleg@redhat.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Kyle Huey <khuey@pernos.co>
Subject: Re: arm64: Register modification during syscall entry/exit stop
Date: Wed, 27 May 2020 10:55:29 +0100 [thread overview]
Message-ID: <20200527095528.GC11111@willie-the-truck> (raw)
In-Reply-To: <CABV8kRxfet2RXXNcUoTKwfVzFWEQfxAkXUX4M5XhkP3nc-0+rQ@mail.gmail.com>
On Sun, May 24, 2020 at 02:56:35AM -0400, Keno Fischer wrote:
> Just ran into this issue again, with what I think may be most compelling
> example yet why this is problematic:
>
> The tracee incurred a signal, we PTRACE_SYSEMU'd to the rt_sigreturn,
> which the tracer tried to emulate by applying the state from the signal frame.
> However, the PTRACE_SYSEMU stop is a syscall-stop, so the tracer's write
> to x7 was ignored and x7 retained the value it had in the signal handler,
> which broke the tracee.
Yeah, that sounds like a good justification to add a way to stop this. Could
you send a patch, please?
Interestingly, I *thought* the current behaviour was needed by strace, but I
can't find anything there that seems to require it. Oh well, we're stuck
with it anyway.
Will
next prev parent reply other threads:[~2020-05-27 9:55 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 1:05 arm64: Register modification during syscall entry/exit stop Keno Fischer
2020-05-19 8:15 ` Will Deacon
2020-05-19 8:37 ` Keno Fischer
2020-05-20 17:41 ` Will Deacon
2020-05-23 5:35 ` Keno Fischer
2020-05-24 6:56 ` Keno Fischer
2020-05-27 9:55 ` Will Deacon [this message]
2020-05-27 10:19 ` Dave Martin
2020-05-31 9:33 ` Will Deacon
2020-05-31 16:13 ` Keno Fischer
2020-06-01 9:14 ` Dave Martin
2020-06-01 9:23 ` Keno Fischer
2020-06-01 9:52 ` Dave Martin
2020-05-31 16:20 ` Keno Fischer
2020-06-01 9:23 ` Dave Martin
2020-06-01 9:40 ` Keno Fischer
2020-06-01 9:59 ` Dave Martin
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