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From: "Dmitry V. Levin" <ldv@altlinux.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Elvira Khabirova <lineprinter@altlinux.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@kernel.org>, Andy Lutomirski <luto@kernel.org>,
	Eugene Syromyatnikov <esyr@redhat.com>,
	linux-kernel@vger.kernel.org, strace-devel@lists.strace.io
Subject: Re: [RFC PATCH] ptrace: add PTRACE_GET_SYSCALL_INFO request
Date: Wed, 7 Nov 2018 19:12:44 +0300	[thread overview]
Message-ID: <20181107161244.GA27809@altlinux.org> (raw)
In-Reply-To: <20181107112100.GA20419@redhat.com>

On Wed, Nov 07, 2018 at 12:21:01PM +0100, Oleg Nesterov wrote:
> On 11/07, Elvira Khabirova wrote:
> >
> > In short, if a 64-bit task performs a syscall through int 0x80, its tracer
> > has no reliable means to find out that the syscall was, in fact,
> > a compat syscall, and misidentifies it.
> > * Syscall-enter-stop and syscall-exit-stop look the same for the tracer.
> 
> Yes, this was discussed many times...
> 
> So perhaps it makes sense to encode compat/is_enter in ->ptrace_message,
> debugger can use PTRACE_GETEVENTMSG to get this info.

This would mean for the debugger an extra syscall invocation for each
syscall stop.  When strace doesn't have to fetch memory, it invokes three
syscalls per syscall stop (wait4, PTRACE_GETREGSET, and PTRACE_SYSCALL).
We definitely want to avoid adding PTRACE_GETEVENTMSG on top of that.


-- 
ldv

  parent reply	other threads:[~2018-11-07 16:12 UTC|newest]

Thread overview: 84+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-07  3:27 Elvira Khabirova
2018-11-07 11:21 ` Oleg Nesterov
2018-11-07 14:06   ` Andy Lutomirski
2018-11-07 16:44     ` Oleg Nesterov
2018-11-07 20:02       ` Elvira Khabirova
2018-11-08  9:16         ` Oleg Nesterov
2018-11-07 20:20       ` Andy Lutomirski
2018-11-08 14:33         ` Oleg Nesterov
2018-11-07 16:12   ` Dmitry V. Levin [this message]
2018-11-07 15:50 ` Dmitry V. Levin
2018-11-07 20:44 ` Andy Lutomirski
2018-11-09  3:13   ` [PATCH 00/13] Prepare for PTRACE_GET_SYSCALL_INFO Dmitry V. Levin
2018-11-09  3:15     ` [PATCH 01/13] Move EM_HEXAGON to uapi/linux/elf-em.h Dmitry V. Levin
2018-11-09  3:15     ` [PATCH 02/13] elf-em.h: add EM_ARC Dmitry V. Levin
2018-11-09 14:20       ` Alexey Brodkin
2018-11-09 16:41       ` Vineet Gupta
2018-11-09 21:44         ` Dmitry V. Levin
2018-11-09 23:33           ` [PATCH 02/13 v2] Move EM_ARCOMPACT and EM_ARCV2 to uapi/linux/elf-em.h Dmitry V. Levin
2018-11-09 23:42             ` Vineet Gupta
2018-11-09  3:15     ` [PATCH 03/13] elf-em.h: add EM_NDS32 Dmitry V. Levin
2018-11-09  3:15     ` [PATCH 04/13] elf-em.h: add EM_XTENSA Dmitry V. Levin
2018-11-09  6:45       ` Max Filippov
2018-11-09  3:15     ` [PATCH 05/13] m68k: define syscall_get_arch() Dmitry V. Levin
2018-11-09  3:16     ` [PATCH 06/13] arc: " Dmitry V. Levin
2018-11-09 14:22       ` Alexey Brodkin
2018-11-09 15:17         ` Andy Lutomirski
2018-11-09 15:27           ` Alexey Brodkin
2018-11-09 15:56             ` Andy Lutomirski
2018-11-09 16:11               ` Alexey Brodkin
2018-11-09 16:35                 ` Andy Lutomirski
2018-11-09 23:33                   ` [PATCH 06/13 v2] " Dmitry V. Levin
2018-11-09 23:39                     ` Vineet Gupta
2018-11-09 23:54                       ` [PATCH 06/13 v3] " Dmitry V. Levin
2018-11-10  0:06                         ` Vineet Gupta
2018-11-09 16:50       ` [PATCH 06/13] " Vineet Gupta
2018-11-09 19:03         ` Andy Lutomirski
2018-11-09 19:13           ` Vineet Gupta
2018-11-09  3:16     ` [PATCH 07/13] c6x: " Dmitry V. Levin
2018-11-10  2:01       ` [PATCH 07/13 v2] " Dmitry V. Levin
2018-11-09  3:16     ` [PATCH 08/13] h8300: " Dmitry V. Levin
2018-11-09  3:16     ` [PATCH 09/13] hexagon: " Dmitry V. Levin
2018-11-09  3:16     ` [PATCH 10/13] nds32: " Dmitry V. Levin
2018-11-10  2:01       ` [PATCH 10/13 v2] " Dmitry V. Levin
2018-11-09  3:17     ` [PATCH 11/13] nios2: " Dmitry V. Levin
2018-11-09  3:17     ` [PATCH 12/13] riscv: " Dmitry V. Levin
2018-11-09  6:59       ` David Abdurachmanov
2018-11-09 22:28         ` Dmitry V. Levin
2018-11-10  5:12           ` David Abdurachmanov
2018-11-10  9:27           ` Andreas Schwab
2018-11-09 18:45       ` Palmer Dabbelt
2018-11-09 21:31         ` Dmitry V. Levin
2018-11-09 22:48           ` [PATCH 12/13 v2] " Dmitry V. Levin
2018-11-11 21:21             ` Palmer Dabbelt
2018-11-09  3:17     ` [PATCH 13/13] xtensa: " Dmitry V. Levin
2018-11-09  6:48       ` Max Filippov
2018-11-09  6:06     ` [PATCH 00/13] Prepare for PTRACE_GET_SYSCALL_INFO Andy Lutomirski
2018-11-10 14:09     ` [PATCH 14/13] Move EM_UNICORE to uapi/linux/elf-em.h Dmitry V. Levin
2018-11-10 14:10     ` [PATCH 15/13] unicore32: define syscall_get_arch() Dmitry V. Levin
2018-11-13  3:38   ` [RFC PATCH] ptrace: add PTRACE_GET_SYSCALL_INFO request Dmitry V. Levin
2018-11-20  0:11   ` [PATCH v2 00/15] Prepare for PTRACE_GET_SYSCALL_INFO Dmitry V. Levin
2018-11-20  0:14     ` [PATCH v2 01/15] Move EM_HEXAGON to uapi/linux/elf-em.h Dmitry V. Levin
2018-11-20  0:14     ` [PATCH v2 02/15] Move EM_ARCOMPACT and EM_ARCV2 " Dmitry V. Levin
2018-11-20  0:14     ` [PATCH v2 03/15] Move EM_UNICORE " Dmitry V. Levin
2018-11-20  0:15     ` [PATCH v2 04/15] elf-em.h: add EM_NDS32 Dmitry V. Levin
2018-11-20  0:15     ` [PATCH v2 05/15] elf-em.h: add EM_XTENSA Dmitry V. Levin
2018-11-20  0:15     ` [PATCH v2 06/15] m68k: define syscall_get_arch() Dmitry V. Levin
2018-12-02 10:29       ` Geert Uytterhoeven
2018-12-03  0:24         ` Dmitry V. Levin
2018-12-03  7:36           ` Geert Uytterhoeven
2018-11-20  0:15     ` [PATCH v2 07/15] arc: " Dmitry V. Levin
2018-11-20  0:15     ` [PATCH v2 08/15] c6x: " Dmitry V. Levin
2018-11-20  0:16     ` [PATCH v2 09/15] h8300: " Dmitry V. Levin
2018-11-20  0:16     ` [PATCH v2 10/15] hexagon: " Dmitry V. Levin
2018-11-20  0:16     ` [PATCH v2 11/15] nds32: " Dmitry V. Levin
2018-11-20  0:16     ` [PATCH v2 12/15] nios2: " Dmitry V. Levin
2018-11-20  0:16     ` [PATCH v2 13/15] riscv: " Dmitry V. Levin
2018-11-20  0:16     ` [PATCH v2 14/15] unicore32: " Dmitry V. Levin
2018-11-20  0:17     ` [PATCH v2 15/15] xtensa: " Dmitry V. Levin
2018-11-20 20:26     ` [PATCH v2 00/15] Prepare for PTRACE_GET_SYSCALL_INFO Paul Moore
     [not found]     ` <20181121004422.GA29053@altlinux.org>
     [not found]       ` <20181121184004.jro532jopnbmru2m@pburton-laptop>
2018-11-21 19:00         ` [PATCH v2 16/15] syscall_get_arch: add "struct task_struct *" argument Dmitry V. Levin
2018-11-21 19:14           ` [PATCH] mips: fix mips_get_syscall_arg o32 check Dmitry V. Levin
2018-11-21 19:23             ` Paul Burton
2018-11-21 19:35           ` [PATCH v2 16/15 v2] syscall_get_arch: add "struct task_struct *" argument Dmitry V. Levin
2018-11-21 19:45             ` Paul Burton

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