From: "H. Peter Anvin" <hpa@zytor.com>
To: Andrew Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>,
x86@kernel.org, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, lueckintel@yahoo.com,
kimwooyoung@gmail.com, Suresh Siddha <suresh.b.siddha@intel.com>
Subject: Re: New vsyscall emulation breaks JITs
Date: Fri, 05 Aug 2011 17:32:10 -0700 [thread overview]
Message-ID: <4E3C8B8A.3080007@zytor.com> (raw)
In-Reply-To: <CAObL_7HPgqvoBm4pkTi9ZmF1K0SsyQWKev_idzjLJ9ST=RO=9A@mail.gmail.com>
On 08/05/2011 05:20 PM, Andrew Lutomirski wrote:
>
> I was thinking of 0x20 - 0x39. 0x40, 0x41, and 0x42 should do the
> trick. I'll cook up a patch.
>
> If you want to keep those vectors available for devices as well, we
> could hook do_general_protection instead, but that's a little messy.
> Are there x86 machines out there that are starved for interrupt
> vectors?
>
Yes, but 3 aren't going to matter much.
However, on systems which have interrupt migration enabled we're not
using 0x21-0x2f for anything (because we need a single interrupt with
absolutely lowest priority). Out of that range, there are a couple of
values which should be safe to use because they would be harmless
instructions of various forms:
0x24 - AND AL, imm8
0x25 - AND EAX, imm32
0x26 - ES:
0x2C - SUB AL, imm8
0x2D - SUB EAX, imm32
0x2E - CS:
[Cc: Suresh who is the expert on the interrupt assignments]
-hpa
next prev parent reply other threads:[~2011-08-06 0:32 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-05 20:09 New vsyscall emulation breaks JITs Andi Kleen
2011-08-05 20:23 ` H. Peter Anvin
2011-08-05 20:26 ` Andi Kleen
2011-08-05 20:36 ` H. Peter Anvin
2011-08-05 20:47 ` Andi Kleen
2011-08-05 20:45 ` Andrew Lutomirski
2011-08-05 20:48 ` H. Peter Anvin
2011-08-05 20:52 ` Andi Kleen
2011-08-05 21:00 ` Andrew Lutomirski
2011-08-05 21:21 ` Andi Kleen
2011-08-05 21:26 ` Andrew Lutomirski
2011-08-05 22:06 ` H. Peter Anvin
2011-08-05 22:11 ` Andrew Lutomirski
2011-08-06 0:20 ` Andrew Lutomirski
2011-08-06 0:32 ` H. Peter Anvin [this message]
2011-08-06 3:01 ` [RFC] x86-64: Allow emulated vsyscalls from user addresses Andy Lutomirski
2011-08-06 3:04 ` [RFC v2] " Andy Lutomirski
2011-08-06 6:45 ` Ingo Molnar
2011-08-07 12:19 ` Borislav Petkov
2011-08-07 12:58 ` Andrew Lutomirski
2011-08-07 15:44 ` Borislav Petkov
2011-08-07 16:14 ` Andrew Lutomirski
2011-08-11 13:16 ` Pavel Machek
2011-08-11 13:27 ` Andrew Lutomirski
2011-08-09 22:27 ` New vsyscall emulation breaks JITs Suresh Siddha
2011-08-09 13:26 ` Andrew Lutomirski
2011-08-09 15:04 ` Andi Kleen
2011-08-09 15:22 ` Andrew Lutomirski
2011-08-09 16:47 ` [RFC] x86-64: Add vsyscall=emulate|native|none option Andy Lutomirski
2011-08-09 19:54 ` Linus Torvalds
2011-08-09 16:57 ` New vsyscall emulation breaks JITs H. Peter Anvin
2011-08-09 17:05 ` Andrew Lutomirski
[not found] ` <1312919938.17118.YahooMailNeo@web120010.mail.ne1.yahoo.com>
2011-08-09 20:59 ` H. Peter Anvin
2011-08-09 21:04 ` Andrew Lutomirski
2011-08-09 22:36 ` Linus Torvalds
2011-08-10 0:56 ` H. Peter Anvin
[not found] ` <1312934493.45753.YahooMailNeo@web120015.mail.ne1.yahoo.com>
2011-08-10 1:49 ` H. Peter Anvin
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