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From:   Keno Fischer <keno@juliacomputing.com>
Date:   Mon, 1 Feb 2021 19:11:12 -0500
Message-ID: <CABV8kRzg1BaKdAhqXU3hONhfPAHj6Nbw0wLBC1Lo7PN1UA0CoA@mail.gmail.com>
Subject: Re: [PATCH 0/3 v2] arm64/ptrace: allow to get all registers on
 syscall traps
To:     Andrei Vagin <avagin@gmail.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>
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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. 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.

Keno