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From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@amd64.org>, Andrew Lutomirski <luto@mit.edu>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>,
	"user-mode-linux-devel@lists.sourceforge.net" 
	<user-mode-linux-devel@lists.sourceforge.net>,
	Richard Weinberger <richard@nod.at>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"mingo@redhat.com" <mingo@redhat.com>
Subject: Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386)
Date: Tue, 23 Aug 2011 17:53:20 +0100	[thread overview]
Message-ID: <20110823165320.GG2203@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CA+55aFxJF88EJ=WhPq08j4+REBgpvVHVwbg5BR05DD+exRyp8A@mail.gmail.com>

On Tue, Aug 23, 2011 at 09:29:29AM -0700, Linus Torvalds wrote:

> Oh yes.
> 
> System call performance is *important*. And x86 is *important*.
> 
> UML? In comparison, not that important.
> 
> So quite frankly, if this is purely an UML issue (and unless we're
> missing something else, that's what it looks like, despite all the
> confusion we've had so far), then if we have a choice between "remove
> syscall instruction" and "remove UML", then ...

Agreed.  Note, BTW, that UML has perfectly usable workaround for 99% of
that - don't tell the binaries it has *any* vdso in such cases.  And
"remove UML" turns into "remove support under UML for 32bit binaries
that go out of their way to do SYSCALL directly, which wouldn't work
on native 32bit", which is really a no-brainer.

WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Lutomirski <luto@mit.edu>,
	"user-mode-linux-devel@lists.sourceforge.net"
	<user-mode-linux-devel@lists.sourceforge.net>,
	Richard Weinberger <richard@nod.at>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Borislav Petkov <bp@amd64.org>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>
Subject: Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386)
Date: Tue, 23 Aug 2011 17:53:20 +0100	[thread overview]
Message-ID: <20110823165320.GG2203@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CA+55aFxJF88EJ=WhPq08j4+REBgpvVHVwbg5BR05DD+exRyp8A@mail.gmail.com>

On Tue, Aug 23, 2011 at 09:29:29AM -0700, Linus Torvalds wrote:

> Oh yes.
> 
> System call performance is *important*. And x86 is *important*.
> 
> UML? In comparison, not that important.
> 
> So quite frankly, if this is purely an UML issue (and unless we're
> missing something else, that's what it looks like, despite all the
> confusion we've had so far), then if we have a choice between "remove
> syscall instruction" and "remove UML", then ...

Agreed.  Note, BTW, that UML has perfectly usable workaround for 99% of
that - don't tell the binaries it has *any* vdso in such cases.  And
"remove UML" turns into "remove support under UML for 32bit binaries
that go out of their way to do SYSCALL directly, which wouldn't work
on native 32bit", which is really a no-brainer.

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  reply	other threads:[~2011-08-23 16:53 UTC|newest]

Thread overview: 161+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-18 18:58 Subject: [PATCH 00/91] pending uml patches Al Viro
2011-08-18 18:58 ` [uml-devel] " Al Viro
2011-08-18 19:12 ` Richard Weinberger
2011-08-18 19:12   ` [uml-devel] " Richard Weinberger
2011-08-18 19:19   ` Al Viro
2011-08-18 19:19     ` [uml-devel] " Al Viro
2011-08-19  4:31     ` Al Viro
2011-08-19  8:51       ` Richard Weinberger
2011-08-19  8:51         ` [uml-devel] " 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             ` Al Viro
2011-08-20 20:14               ` [uml-devel] " 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                   ` Richard Weinberger
2011-08-20 21:38                     ` [uml-devel] " Richard Weinberger
2011-08-20 21:40                   ` Andrew Lutomirski
2011-08-20 21:40                     ` [uml-devel] " Andrew Lutomirski
2011-08-21  6:34                     ` Al Viro
2011-08-21  6:34                       ` [uml-devel] " Al Viro
2011-08-21  8:42                       ` SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) Al Viro
2011-08-21  8:42                         ` [uml-devel] " Al Viro
2011-08-21 11:24                         ` Andrew Lutomirski
2011-08-21 11:24                           ` [uml-devel] " Andrew Lutomirski
2011-08-21 13:37                           ` Andrew Lutomirski
2011-08-21 13:37                             ` [uml-devel] " Andrew Lutomirski
2011-08-21 14:51                             ` Al Viro
2011-08-21 14:51                               ` [uml-devel] " Al Viro
2011-08-21 14:43                           ` Al Viro
2011-08-21 16:41                             ` Al Viro
2011-08-21 16:41                               ` [uml-devel] " 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                                   ` Al Viro
2011-08-22  1:19                                     ` [uml-devel] " Al Viro
2011-08-22  1:19                                   ` H. Peter Anvin
2011-08-22  1:19                                     ` [uml-devel] " 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                                 ` SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) Al Viro
2011-08-22  1:16                                   ` [uml-devel] " Al Viro
2011-08-22  1:41                                   ` Linus Torvalds
2011-08-22  1:41                                     ` [uml-devel] " Linus Torvalds
2011-08-22  1:48                                     ` H. Peter Anvin
2011-08-22  1:48                                       ` [uml-devel] " H. Peter Anvin
2011-08-22  2:01                                       ` Andrew Lutomirski
2011-08-22  2:01                                         ` [uml-devel] " Andrew Lutomirski
2011-08-22  2:07                                         ` Al Viro
2011-08-22  2:07                                           ` [uml-devel] " Al Viro
2011-08-22  2:26                                           ` Andrew Lutomirski
2011-08-22  2:26                                             ` [uml-devel] " Andrew Lutomirski
2011-08-22  2:34                                             ` H. Peter Anvin
2011-08-22  2:34                                               ` [uml-devel] " H. Peter Anvin
2011-08-22  4:05                                             ` H. Peter Anvin
2011-08-22  4:05                                               ` [uml-devel] " H. Peter Anvin
2011-08-22  9:53                                               ` 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 [this message]
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                                       ` H. Peter Anvin
2011-08-22  4:11                                         ` [uml-devel] " H. Peter Anvin
2011-08-22  4:26                                         ` Al Viro
2011-08-22  4:26                                           ` [uml-devel] " Al Viro
2011-08-22  5:03                                           ` H. Peter Anvin
2011-08-22  5:03                                             ` [uml-devel] " H. Peter Anvin
2011-08-23  5:10                                             ` Andrew Lutomirski
2011-08-23  5:10                                               ` [uml-devel] " Andrew Lutomirski

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