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From: Andrei Vagin <avagin@gmail.com>
To: Keno Fischer <keno@juliacomputing.com>
Cc: Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Oleg Nesterov <oleg@redhat.com>,
	linux-arm-kernel@lists.infradead.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-api@vger.kernel.org,
	Anthony Steinhauser <asteinhauser@google.com>,
	Dave Martin <Dave.Martin@arm.com>, Kyle Huey <khuey@pernos.co>,
	Robert O'Callahan <roc@pernos.co>
Subject: Re: [PATCH 0/3 v2] arm64/ptrace: allow to get all registers on syscall traps
Date: Mon, 8 Feb 2021 10:37:52 -0800	[thread overview]
Message-ID: <20210208183752.GB559391@gmail.com> (raw)
In-Reply-To: <CABV8kRzg1BaKdAhqXU3hONhfPAHj6Nbw0wLBC1Lo7PN1UA0CoA@mail.gmail.com>

On Mon, Feb 01, 2021 at 07:11:12PM -0500, Keno Fischer wrote:
> Hi Andrei,
> 
> > This series introduces the PTRACE_O_ARM64_RAW_REGS option. If it is set,
> > PTRACE_GETREGSET returns values of all registers, and PTRACE_SETREGSET
> > allows to change any of them.
> 
> thanks for picking this up. I meant to work on this, but unfortunately ran out
> of time to be able to push it through, so I'm glad you're working on
> it, since it
> does absolutely need to get fixed. Besides this issue, the other problem we
> ran into when trying to port our ptracer to aarch64 is that orig_x0 is not
> accessible through the ptrace interface on aarch64, which can cause tricky
> behavior around restarts.

Could you describe the problem in more details? I wonder whether we have
the same thing in CRIU...

> We managed to work around that in the end,
> but it's painful. If we're fixing the kernel here anyway, I'm wondering if
> we might want to address that as well while we're at it.

Sure let think how to do this properly.

In this case, I think the ptrace option isn't a good choise. I don't
think that it is a good idea to change the layout of regset depending on
options...

Thanks,
Andrei

> 
> Keno

WARNING: multiple messages have this Message-ID (diff)
From: Andrei Vagin <avagin@gmail.com>
To: Keno Fischer <keno@juliacomputing.com>
Cc: Kyle Huey <khuey@pernos.co>,
	Anthony Steinhauser <asteinhauser@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Oleg Nesterov <oleg@redhat.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Robert O'Callahan <roc@pernos.co>,
	linux-api@vger.kernel.org, Will Deacon <will@kernel.org>,
	Dave Martin <Dave.Martin@arm.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/3 v2] arm64/ptrace: allow to get all registers on syscall traps
Date: Mon, 8 Feb 2021 10:37:52 -0800	[thread overview]
Message-ID: <20210208183752.GB559391@gmail.com> (raw)
In-Reply-To: <CABV8kRzg1BaKdAhqXU3hONhfPAHj6Nbw0wLBC1Lo7PN1UA0CoA@mail.gmail.com>

On Mon, Feb 01, 2021 at 07:11:12PM -0500, Keno Fischer wrote:
> Hi Andrei,
> 
> > This series introduces the PTRACE_O_ARM64_RAW_REGS option. If it is set,
> > PTRACE_GETREGSET returns values of all registers, and PTRACE_SETREGSET
> > allows to change any of them.
> 
> thanks for picking this up. I meant to work on this, but unfortunately ran out
> of time to be able to push it through, so I'm glad you're working on
> it, since it
> does absolutely need to get fixed. Besides this issue, the other problem we
> ran into when trying to port our ptracer to aarch64 is that orig_x0 is not
> accessible through the ptrace interface on aarch64, which can cause tricky
> behavior around restarts.

Could you describe the problem in more details? I wonder whether we have
the same thing in CRIU...

> We managed to work around that in the end,
> but it's painful. If we're fixing the kernel here anyway, I'm wondering if
> we might want to address that as well while we're at it.

Sure let think how to do this properly.

In this case, I think the ptrace option isn't a good choise. I don't
think that it is a good idea to change the layout of regset depending on
options...

Thanks,
Andrei

> 
> Keno

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  reply	other threads:[~2021-02-08 20:12 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-01 19:40 [PATCH 0/3 v2] arm64/ptrace: allow to get all registers on syscall traps Andrei Vagin
2021-02-01 19:40 ` Andrei Vagin
2021-02-01 19:40 ` [PATCH 1/3] arm64/ptrace: don't clobber task registers on syscall entry/exit traps Andrei Vagin
2021-02-01 19:40   ` Andrei Vagin
2021-02-04 15:23   ` Will Deacon
2021-02-04 15:23     ` Will Deacon
2021-02-04 16:41     ` Dave Martin
2021-02-04 16:41       ` Dave Martin
2021-02-25 16:00     ` Andrei Vagin
2021-02-25 16:00       ` Andrei Vagin
2021-02-01 19:40 ` [PATCH 2/3] arm64/ptrace: introduce PTRACE_O_ARM64_RAW_REGS Andrei Vagin
2021-02-01 19:40   ` Andrei Vagin
2021-02-04 15:36   ` Will Deacon
2021-02-04 15:36     ` Will Deacon
2021-02-08 18:31     ` Andrei Vagin
2021-02-08 18:31       ` Andrei Vagin
2021-02-01 19:40 ` [PATCH 3/3] selftest/arm64/ptrace: add tests for PTRACE_O_ARM64_RAW_REGS Andrei Vagin
2021-02-01 19:40   ` Andrei Vagin
2021-02-04 15:40   ` Will Deacon
2021-02-04 15:40     ` Will Deacon
2021-02-10 20:54     ` Kees Cook
2021-02-10 20:54       ` Kees Cook
2021-02-02  0:11 ` [PATCH 0/3 v2] arm64/ptrace: allow to get all registers on syscall traps Keno Fischer
2021-02-02  0:11   ` Keno Fischer
2021-02-08 18:37   ` Andrei Vagin [this message]
2021-02-08 18:37     ` Andrei Vagin
2021-02-08 19:18     ` Keno Fischer
2021-02-08 19:18       ` Keno Fischer
2021-02-04 14:53 ` Will Deacon
2021-02-04 14:53   ` Will Deacon

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