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From: Dave Martin <Dave.Martin@arm•com>
To: Keno Fischer <keno@juliacomputing•com>
Cc: Kyle Huey <khuey@pernos•co>,
	Catalin Marinas <catalin.marinas@arm•com>,
	Linux Kernel Mailing List <linux-kernel@vger•kernel.org>,
	Oleg Nesterov <oleg@redhat•com>, Will Deacon <will@kernel•org>,
	linux-arm-kernel@lists•infradead.org
Subject: Re: arm64: Register modification during syscall entry/exit stop
Date: Mon, 1 Jun 2020 10:14:41 +0100	[thread overview]
Message-ID: <20200601091441.GW5031@arm.com> (raw)
In-Reply-To: <CABV8kRyHo+EAWaMUzGA220z=HJRBCpH6UWiYGb84uSL3h8HQHw@mail.gmail.com>

On Sun, May 31, 2020 at 12:13:18PM -0400, Keno Fischer wrote:
> > Keno -- are you planning to send out a patch? You previously spoke about
> > implementing this using PTRACE_SETOPTIONS.
> 
> Yes, I'll have a patch for you. Though I've come to the conclusion
> that introducing a new regset is probably a better way to solve it.
> We can then also expose orig_x0 at the same time and give it sane semantics
> (there's some problems with the way it works currently - I'll write it up
> together with the patch).

I'd worry that having a new ptrace option would be useless bug-
compatibility that is just going to bitrot.

Can you explain why userspace would write a changed value for x7
but at the same time need that new to be thrown away?

That sounds like a nonsensical thing for userspace to be doing.

Cheers
---Dave

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next prev parent reply	other threads:[~2020-06-01  9:14 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
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 [this message]
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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