From: "Michał Mirosław" <emmir@google.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Piotr Figiel <figiel@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.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>,
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: Fri, 26 Feb 2021 17:04:25 +0100 [thread overview]
Message-ID: <CABb0KFFhbxU0xq0A=m2FO83j04vrzwVa2-JwKJi1mtRhu_0kSg@mail.gmail.com> (raw)
In-Reply-To: <192824546.8190.1614353555831.JavaMail.zimbra@efficios.com>
On Fri, 26 Feb 2021 at 16:32, Mathieu Desnoyers
<mathieu.desnoyers@efficios.com> wrote:
>
> ----- On Feb 26, 2021, at 8:51 AM, Piotr Figiel figiel@google.com wrote:
> [...]
> > ---
> > v2:
> > Applied review comments:
> > - changed return value from the ptrace request to the size of the
> > configuration structure
> > - expanded configuration structure with the flags field and
> > the rseq abi structure size
> >
> [...]
> > +#define PTRACE_GET_RSEQ_CONFIGURATION 0x420f
> > +
> > +struct ptrace_rseq_configuration {
> > + __u64 rseq_abi_pointer;
> > + __u32 rseq_abi_size;
> > + __u32 signature;
> > + __u32 flags;
> > + __u32 pad;
> > +};
> > +
> [...]
> > +#ifdef CONFIG_RSEQ
> > +static long ptrace_get_rseq_configuration(struct task_struct *task,
> > + unsigned long size, void __user *data)
> > +{
> > + struct ptrace_rseq_configuration conf = {
> > + .rseq_abi_pointer = (u64)(uintptr_t)task->rseq,
> > + .rseq_abi_size = sizeof(*task->rseq),
> > + .signature = task->rseq_sig,
> > + .flags = 0,
> > + };
> > +
> > + size = min_t(unsigned long, size, sizeof(conf));
> > + if (copy_to_user(data, &conf, size))
> > + return -EFAULT;
> > + return sizeof(conf);
> > +}
>
> I think what Florian was after would be:
>
> struct ptrace_rseq_configuration {
> __u32 size; /* size of struct ptrace_rseq_configuration */
> __u32 flags;
> __u64 rseq_abi_pointer;
> __u32 signature;
> __u32 pad;
> };
>
> where:
>
> .size = sizeof(struct ptrace_rseq_configuration),
>
> This way, the configuration structure can be expanded in the future. The
> rseq ABI structure is by definition fixed-size, so there is no point in
> having its size here.
>
> Florian, did I understand your request correctly, or am I missing your point ?
In this case returning sizeof(conf) would serve the same purpose, wouldn't it?
Best Regards
Michał Mirosław
[Resent because of HTML mail misfeature...]
next prev parent reply other threads:[~2021-02-26 16:05 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 [this message]
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
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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