From: "Dmitry V. Levin" <ldv-u2l5PoMzF/Vg9hUCZPvPmw@public.gmane.org>
To: Joey Pabalinas <joeypabalinas-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org>,
Eugene Syromyatnikov
<esyr-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
strace-devel-3+4lAyCyj6AWlMsSdNXQLw@public.gmane.org,
Andy Lutomirski <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH RESEND v3 1/3] ptrace: pass type of a syscall-stop in ptrace_message
Date: Sun, 25 Nov 2018 05:10:59 +0300 [thread overview]
Message-ID: <20181125021059.GA1190@altlinux.org> (raw)
In-Reply-To: <20181125015402.glcaw3kghcu4pr22-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
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On Sat, Nov 24, 2018 at 03:54:02PM -1000, Joey Pabalinas wrote:
> On Sun, Nov 25, 2018 at 02:22:27AM +0100, Elvira Khabirova wrote:
> > Define two constants, PTRACE_EVENTMSG_SYSCALL_ENTRY and
> > PTRACE_EVENTMSG_SYSCALL_EXIT, and place them in ptrace_message
> > for the duration of syscall-stops.
> > This way ptracers can distinguish syscall-enter-stops
> > from syscall-exit-stops using PTRACE_GETEVENTMSG request.
>
> Is there an advantage to using two constants instead of a single
> sys_exit bit (set/unset for syscall-exit-stop/syscall-enter-stop)?
Given that without this patch the value returned by PTRACE_GETEVENTMSG
during syscall stop is undefined, we need two different ptrace_message
values that cannot be set by other ptrace events to enable reliable
identification of syscall-enter-stop and syscall-exit-stop in userspace:
if we make PTRACE_GETEVENTMSG return 0 or any other value routinely set by
other ptrace events, it would be hard for userspace to find out whether
the kernel implements new semantics or not.
--
ldv
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WARNING: multiple messages have this Message-ID (diff)
From: "Dmitry V. Levin" <ldv@altlinux.org>
To: Joey Pabalinas <joeypabalinas@gmail.com>
Cc: Elvira Khabirova <lineprinter@altlinux.org>,
Oleg Nesterov <oleg@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>, Andy Lutomirski <luto@kernel.org>,
Eugene Syromyatnikov <esyr@redhat.com>,
linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
strace-devel@lists.strace.io
Subject: Re: [PATCH RESEND v3 1/3] ptrace: pass type of a syscall-stop in ptrace_message
Date: Sun, 25 Nov 2018 05:10:59 +0300 [thread overview]
Message-ID: <20181125021059.GA1190@altlinux.org> (raw)
In-Reply-To: <20181125015402.glcaw3kghcu4pr22@gmail.com>
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On Sat, Nov 24, 2018 at 03:54:02PM -1000, Joey Pabalinas wrote:
> On Sun, Nov 25, 2018 at 02:22:27AM +0100, Elvira Khabirova wrote:
> > Define two constants, PTRACE_EVENTMSG_SYSCALL_ENTRY and
> > PTRACE_EVENTMSG_SYSCALL_EXIT, and place them in ptrace_message
> > for the duration of syscall-stops.
> > This way ptracers can distinguish syscall-enter-stops
> > from syscall-exit-stops using PTRACE_GETEVENTMSG request.
>
> Is there an advantage to using two constants instead of a single
> sys_exit bit (set/unset for syscall-exit-stop/syscall-enter-stop)?
Given that without this patch the value returned by PTRACE_GETEVENTMSG
during syscall stop is undefined, we need two different ptrace_message
values that cannot be set by other ptrace events to enable reliable
identification of syscall-enter-stop and syscall-exit-stop in userspace:
if we make PTRACE_GETEVENTMSG return 0 or any other value routinely set by
other ptrace events, it would be hard for userspace to find out whether
the kernel implements new semantics or not.
--
ldv
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next prev parent reply other threads:[~2018-11-25 2:10 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-25 1:21 [PATCH RESEND v3 0/3] ptrace: add PTRACE_GET_SYSCALL_INFO request Elvira Khabirova
2018-11-25 1:21 ` Elvira Khabirova
2018-11-25 1:22 ` [PATCH RESEND v3 1/3] ptrace: pass type of a syscall-stop in ptrace_message Elvira Khabirova
2018-11-25 1:22 ` Elvira Khabirova
2018-11-25 1:54 ` Joey Pabalinas
[not found] ` <20181125015402.glcaw3kghcu4pr22-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-11-25 2:10 ` Dmitry V. Levin [this message]
2018-11-25 2:10 ` Dmitry V. Levin
[not found] ` <20181125021059.GA1190-u2l5PoMzF/Vg9hUCZPvPmw@public.gmane.org>
2018-11-25 6:17 ` Joey Pabalinas
2018-11-25 6:17 ` Joey Pabalinas
2018-11-26 14:56 ` Oleg Nesterov
[not found] ` <20181126145643.GD1660-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2018-11-27 2:53 ` Elvira Khabirova
2018-11-27 2:53 ` Elvira Khabirova
2018-11-27 3:48 ` Dmitry V. Levin
2018-11-25 1:23 ` [PATCH RESEND v3 2/3] ptrace: add PTRACE_GET_SYSCALL_INFO request Elvira Khabirova
2018-11-25 1:23 ` Elvira Khabirova
2018-11-25 1:23 ` [RFC PATCH RESEND v3 3/3] ptrace: add PTRACE_EVENT_SECCOMP support to PTRACE_GET_SYSCALL_INFO Elvira Khabirova
2018-11-25 1:23 ` Elvira Khabirova
2018-11-26 14:35 ` Oleg Nesterov
2018-11-26 14:35 ` Oleg Nesterov
[not found] ` <20181126143524.GB1660-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2018-11-27 3:07 ` Elvira Khabirova
2018-11-27 3:07 ` Elvira Khabirova
2018-11-27 3:21 ` Dmitry V. Levin
2018-11-27 3:21 ` Dmitry V. Levin
2018-11-27 12:31 ` Oleg Nesterov
[not found] ` <20181127123116.GA13284-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2018-11-27 23:27 ` Dmitry V. Levin
2018-11-27 23:27 ` Dmitry V. Levin
2018-11-28 12:35 ` Oleg Nesterov
[not found] ` <20181128123545.GA30395-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2018-11-28 12:44 ` Dmitry V. Levin
2018-11-28 12:44 ` Dmitry V. Levin
2018-11-28 13:13 ` Oleg Nesterov
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