From: "H. Peter Anvin" <hpa@zytor.com>
To: Borislav Petkov <bp@amd64.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>,
"mingo@redhat.com" <mingo@redhat.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Linus Torvalds <torvalds@linux-foundation.org>,
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 12:15:58 -0700 [thread overview]
Message-ID: <4E53FC6E.1030807@zytor.com> (raw)
In-Reply-To: <20110823162251.GC13138@aftab>
On 08/23/2011 09:22 AM, Borislav Petkov wrote:
> On Tue, Aug 23, 2011 at 12:11:43PM -0400, Andrew Lutomirski wrote:
>> In any case, this seems insanely overcomplicated. I'd be less afraid
>> of something like my approach (which, I think, makes all of the
>> SYSCALL weirdness pretty much transparent to ptrace users) or of just
>> removing SYSCALL entirely from 32-bit code.
>
> I don't think that removing SYSCALL from 32-bit code just so that UML
> trapped syscalls work is something we'd like since SYSCALL is much
> cheaper than INT $0x80:
>
> "As a result, SYSCALL and SYSRET can take fewer than one-fourth the
> number of internal clock cycles to complete than the legacy CALL and RET
> instructions."
>
> http://support.amd.com/us/Processor_TechDocs/24593.pdf, p. 152.
>
> I know, it is 32-bit syscall on 64-bit kernel which should be pretty
> rare but still...
>
Right, but if you had said the difference had disappeared on current AMD
silicon it would be much less of an issue. That's why I wanted to find
that bit out from you.
-hpa
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WARNING: multiple messages have this Message-ID (diff)
From: "H. Peter Anvin" <hpa@zytor.com>
To: Borislav Petkov <bp@amd64.org>
Cc: Andrew Lutomirski <luto@mit.edu>,
Linus Torvalds <torvalds@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>, 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 12:15:58 -0700 [thread overview]
Message-ID: <4E53FC6E.1030807@zytor.com> (raw)
In-Reply-To: <20110823162251.GC13138@aftab>
On 08/23/2011 09:22 AM, Borislav Petkov wrote:
> On Tue, Aug 23, 2011 at 12:11:43PM -0400, Andrew Lutomirski wrote:
>> In any case, this seems insanely overcomplicated. I'd be less afraid
>> of something like my approach (which, I think, makes all of the
>> SYSCALL weirdness pretty much transparent to ptrace users) or of just
>> removing SYSCALL entirely from 32-bit code.
>
> I don't think that removing SYSCALL from 32-bit code just so that UML
> trapped syscalls work is something we'd like since SYSCALL is much
> cheaper than INT $0x80:
>
> "As a result, SYSCALL and SYSRET can take fewer than one-fourth the
> number of internal clock cycles to complete than the legacy CALL and RET
> instructions."
>
> http://support.amd.com/us/Processor_TechDocs/24593.pdf, p. 152.
>
> I know, it is 32-bit syscall on 64-bit kernel which should be pretty
> rare but still...
>
Right, but if you had said the difference had disappeared on current AMD
silicon it would be much less of an issue. That's why I wanted to find
that bit out from you.
-hpa
next prev parent reply other threads:[~2011-08-23 19:16 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 [this message]
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 ` [uml-devel] " H. Peter Anvin
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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