From: "H. Peter Anvin" <hpa@zytor.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Andrew Lutomirski <luto@mit.edu>,
user-mode-linux-devel@lists.sourceforge.net,
Richard Weinberger <richard@nod.at>,
linux-kernel@vger.kernel.org, mingo@redhat.com,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386)
Date: Sun, 21 Aug 2011 22:03:33 -0700 [thread overview]
Message-ID: <4E51E325.2050502@zytor.com> (raw)
In-Reply-To: <20110822042605.GR2203@ZenIV.linux.org.uk>
On 08/21/2011 09:26 PM, Al Viro wrote:
> On Sun, Aug 21, 2011 at 09:11:54PM -0700, H. Peter Anvin wrote:
>>> lack of point - the *only* CPU where it would matter would be K6-2, IIRC,
>>> and (again, IIRC) it had some differences in SYSCALL semantics compared to
>>> K7 (which supports SYSENTER as well). Bugger if I remember what those
>>> differences might've been... Some flag not cleared?
>>
>> The most likely reason for a binary to execute a stray SYSCALL is
>> because they read it out of the vdso. Totally daft, but we certainly
>> see a lot of stupid things as evidenced by the JIT thread earlier this
>> month.
>
> Um... What, blindly, no matter what surrounds it in there? What will
> happen to the same eager JIT when it steps on SYSENTER?
The JIT will have had to manage SYSENTER already. It's not a change,
whereas SYSCALL would be. We could just try it, and see if anything
breaks, of course.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
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WARNING: multiple messages have this Message-ID (diff)
From: "H. Peter Anvin" <hpa@zytor.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Lutomirski <luto@mit.edu>,
mingo@redhat.com, Richard Weinberger <richard@nod.at>,
user-mode-linux-devel@lists.sourceforge.net,
linux-kernel@vger.kernel.org
Subject: Re: SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386)
Date: Sun, 21 Aug 2011 22:03:33 -0700 [thread overview]
Message-ID: <4E51E325.2050502@zytor.com> (raw)
In-Reply-To: <20110822042605.GR2203@ZenIV.linux.org.uk>
On 08/21/2011 09:26 PM, Al Viro wrote:
> On Sun, Aug 21, 2011 at 09:11:54PM -0700, H. Peter Anvin wrote:
>>> lack of point - the *only* CPU where it would matter would be K6-2, IIRC,
>>> and (again, IIRC) it had some differences in SYSCALL semantics compared to
>>> K7 (which supports SYSENTER as well). Bugger if I remember what those
>>> differences might've been... Some flag not cleared?
>>
>> The most likely reason for a binary to execute a stray SYSCALL is
>> because they read it out of the vdso. Totally daft, but we certainly
>> see a lot of stupid things as evidenced by the JIT thread earlier this
>> month.
>
> Um... What, blindly, no matter what surrounds it in there? What will
> happen to the same eager JIT when it steps on SYSENTER?
The JIT will have had to manage SYSENTER already. It's not a change,
whereas SYSCALL would be. We could just try it, and see if anything
breaks, of course.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2011-08-22 5:03 UTC|newest]
Thread overview: 161+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-18 18:58 [uml-devel] Subject: [PATCH 00/91] pending uml patches Al Viro
2011-08-18 18:58 ` Al Viro
2011-08-18 19:12 ` [uml-devel] " Richard Weinberger
2011-08-18 19:12 ` Richard Weinberger
2011-08-18 19:19 ` [uml-devel] " Al Viro
2011-08-18 19:19 ` Al Viro
2011-08-19 4:31 ` Al Viro
2011-08-19 8:51 ` [uml-devel] " Richard Weinberger
2011-08-19 8:51 ` Richard Weinberger
2011-08-20 1:18 ` [RFC] weird crap with vdso on uml/i386 Al Viro
2011-08-20 15:22 ` Richard Weinberger
2011-08-20 20:14 ` [uml-devel] " Al Viro
2011-08-20 20:14 ` Al Viro
2011-08-20 20:55 ` Richard Weinberger
2011-08-20 21:26 ` Andrew Lutomirski
2011-08-20 21:26 ` Andrew Lutomirski
2011-08-20 21:38 ` [uml-devel] " Richard Weinberger
2011-08-20 21:38 ` Richard Weinberger
2011-08-20 21:40 ` [uml-devel] " Andrew Lutomirski
2011-08-20 21:40 ` Andrew Lutomirski
2011-08-21 6:34 ` [uml-devel] " Al Viro
2011-08-21 6:34 ` Al Viro
2011-08-21 8:42 ` [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) Al Viro
2011-08-21 8:42 ` Al Viro
2011-08-21 11:24 ` [uml-devel] " Andrew Lutomirski
2011-08-21 11:24 ` Andrew Lutomirski
2011-08-21 13:37 ` [uml-devel] " Andrew Lutomirski
2011-08-21 13:37 ` Andrew Lutomirski
2011-08-21 14:51 ` [uml-devel] " Al Viro
2011-08-21 14:51 ` Al Viro
2011-08-21 14:43 ` Al Viro
2011-08-21 16:41 ` [uml-devel] " Al Viro
2011-08-21 16:41 ` Al Viro
2011-08-22 0:44 ` Andrew Lutomirski
2011-08-22 0:44 ` Andrew Lutomirski
2011-08-22 1:09 ` Linus Torvalds
2011-08-22 1:19 ` [uml-devel] " Al Viro
2011-08-22 1:19 ` Al Viro
2011-08-22 1:19 ` [uml-devel] " H. Peter Anvin
2011-08-22 1:19 ` H. Peter Anvin
2011-08-22 21:25 ` [tip:x86/urgent] x86-32, vdso: On system call restart after SYSENTER, use int $0x80 tip-bot for H. Peter Anvin
2011-08-23 23:40 ` tip-bot for H. Peter Anvin
2011-08-22 1:16 ` [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) Al Viro
2011-08-22 1:16 ` Al Viro
2011-08-22 1:41 ` [uml-devel] " Linus Torvalds
2011-08-22 1:41 ` Linus Torvalds
2011-08-22 1:48 ` [uml-devel] " H. Peter Anvin
2011-08-22 1:48 ` H. Peter Anvin
2011-08-22 2:01 ` [uml-devel] " Andrew Lutomirski
2011-08-22 2:01 ` Andrew Lutomirski
2011-08-22 2:07 ` [uml-devel] " Al Viro
2011-08-22 2:07 ` Al Viro
2011-08-22 2:26 ` [uml-devel] " Andrew Lutomirski
2011-08-22 2:26 ` Andrew Lutomirski
2011-08-22 2:34 ` [uml-devel] " H. Peter Anvin
2011-08-22 2:34 ` H. Peter Anvin
2011-08-22 4:05 ` [uml-devel] " H. Peter Anvin
2011-08-22 4:05 ` H. Peter Anvin
2011-08-22 9:53 ` [uml-devel] " Ingo Molnar
2011-08-22 13:34 ` Andrew Lutomirski
2011-08-22 13:34 ` Andrew Lutomirski
2011-08-22 14:40 ` Borislav Petkov
2011-08-22 14:40 ` Borislav Petkov
2011-08-22 15:13 ` Al Viro
2011-08-22 15:13 ` Al Viro
2011-08-22 20:05 ` Linus Torvalds
2011-08-22 20:05 ` Linus Torvalds
2011-08-22 20:11 ` H. Peter Anvin
2011-08-22 20:11 ` H. Peter Anvin
2011-08-22 21:52 ` Andrew Lutomirski
2011-08-22 21:52 ` Andrew Lutomirski
2011-08-22 22:04 ` H. Peter Anvin
2011-08-22 22:04 ` H. Peter Anvin
2011-08-22 23:27 ` Linus Torvalds
2011-08-22 23:46 ` H. Peter Anvin
2011-08-22 23:46 ` H. Peter Anvin
2011-08-23 0:03 ` Al Viro
2011-08-23 0:03 ` Al Viro
2011-08-23 0:07 ` Al Viro
2011-08-23 0:07 ` Al Viro
2011-08-23 0:07 ` H. Peter Anvin
2011-08-23 0:07 ` H. Peter Anvin
2011-08-23 0:22 ` Linus Torvalds
2011-08-23 0:22 ` Linus Torvalds
2011-08-23 1:01 ` Al Viro
2011-08-23 1:13 ` Al Viro
2011-08-23 1:13 ` Al Viro
2011-08-23 1:59 ` Linus Torvalds
2011-08-23 1:59 ` Linus Torvalds
2011-08-23 2:59 ` Al Viro
2011-08-23 2:59 ` Al Viro
2011-08-23 2:17 ` Al Viro
2011-08-23 6:15 ` Al Viro
2011-08-23 14:26 ` Borislav Petkov
2011-08-23 16:30 ` Al Viro
2011-08-23 16:30 ` Al Viro
2011-08-23 16:03 ` Linus Torvalds
2011-08-23 16:03 ` Linus Torvalds
2011-08-23 16:11 ` Andrew Lutomirski
2011-08-23 16:11 ` Andrew Lutomirski
2011-08-23 16:20 ` Linus Torvalds
2011-08-23 16:20 ` Linus Torvalds
2011-08-23 17:33 ` Al Viro
2011-08-23 17:33 ` Al Viro
2011-08-23 18:04 ` Al Viro
2011-08-23 18:04 ` Al Viro
2011-08-24 12:44 ` [PATCH] x86, asm: Document some of the syscall asm glue Borislav Petkov
2011-08-23 16:22 ` [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) Borislav Petkov
2011-08-23 16:29 ` Linus Torvalds
2011-08-23 16:53 ` Al Viro
2011-08-23 16:53 ` Al Viro
2011-08-23 16:58 ` Richard Weinberger
2011-08-23 16:58 ` Richard Weinberger
2011-08-23 17:07 ` Al Viro
2011-08-23 17:07 ` Al Viro
2011-08-23 17:29 ` Richard Weinberger
2011-08-23 17:29 ` Richard Weinberger
2011-08-25 0:05 ` Richard Weinberger
2011-08-23 19:15 ` H. Peter Anvin
2011-08-23 19:15 ` H. Peter Anvin
2011-08-23 20:56 ` Borislav Petkov
2011-08-23 21:06 ` H. Peter Anvin
2011-08-23 21:10 ` Borislav Petkov
2011-08-23 23:04 ` H. Peter Anvin
2011-08-23 23:04 ` H. Peter Anvin
2011-08-24 21:10 ` H. Peter Anvin
2011-08-24 21:10 ` H. Peter Anvin
2011-08-23 16:48 ` Al Viro
2011-08-23 16:48 ` Al Viro
2011-08-23 17:33 ` Linus Torvalds
2011-08-23 17:33 ` Linus Torvalds
2011-08-23 21:08 ` H. Peter Anvin
2011-08-23 21:08 ` H. Peter Anvin
2011-08-23 21:20 ` Linus Torvalds
2011-08-23 21:20 ` Linus Torvalds
2011-08-23 23:04 ` H. Peter Anvin
2011-08-23 23:04 ` H. Peter Anvin
2011-08-23 19:18 ` H. Peter Anvin
2011-08-23 19:18 ` H. Peter Anvin
2011-08-23 19:24 ` Linus Torvalds
2011-08-23 19:24 ` Linus Torvalds
2011-08-23 19:26 ` H. Peter Anvin
2011-08-23 19:26 ` H. Peter Anvin
2011-08-23 19:41 ` Al Viro
2011-08-23 19:41 ` Al Viro
2011-08-23 19:43 ` Linus Torvalds
2011-08-23 19:43 ` Linus Torvalds
2011-08-23 21:17 ` Al Viro
2011-08-23 21:17 ` Al Viro
2011-08-23 1:16 ` Andrew Lutomirski
2011-08-23 1:18 ` H. Peter Anvin
2011-08-23 1:18 ` H. Peter Anvin
2011-08-22 4:07 ` Al Viro
2011-08-22 4:11 ` [uml-devel] " H. Peter Anvin
2011-08-22 4:11 ` H. Peter Anvin
2011-08-22 4:26 ` [uml-devel] " Al Viro
2011-08-22 4:26 ` Al Viro
2011-08-22 5:03 ` H. Peter Anvin [this message]
2011-08-22 5:03 ` H. Peter Anvin
2011-08-23 5:10 ` [uml-devel] " Andrew Lutomirski
2011-08-23 5:10 ` Andrew Lutomirski
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