From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
arjan@linux.intel.com, bp@alien8.de, jpoimboe@redhat.com,
richard.weinberger@gmail.com
Subject: Re: [PATCH] x86: Implement __WARN using UD0
Date: Thu, 23 Feb 2017 15:09:29 +0100 [thread overview]
Message-ID: <20170223140929.GU6536@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20170223132813.GB6515@twins.programming.kicks-ass.net>
On Thu, Feb 23, 2017 at 02:28:13PM +0100, Peter Zijlstra wrote:
> + * Since various instruction decoders disagree on the length of UD1,
> + * we cannot use it either. So use UD0 for WARN.
> + *
> + * (binutils knows about "ud1" but {en,de}codes it as 2 bytes, whereas
> + * our kernel decoder thinks it takes a ModRM byte, which seems consistent
> + * with various things like the Intel SDM instruction encoding rules)
> + */
> +
> +#define ASM_UD0 ".byte 0x0f, 0xff"
> +#define ASM_UD1 ".byte 0x0f, 0xb9" /* + ModRM */
> +#define ASM_UD2 ".byte 0x0f, 0x0b"
http://repo.or.cz/nasm.git/blob/HEAD:/x86/insns.dat
has:
1378 UD0 void [ 0f ff] 186,UNDOC
1379 UD1 void [ 0f b9] 186,UNDOC
1380 UD2B void [ 0f b9] 186,UNDOC,ND
1381 UD2 void [ 0f 0b] 186
1382 UD2A void [ 0f 0b] 186,ND
which seems to use the 2 byte version of UD1.
hpa, any input?
next prev parent reply other threads:[~2017-02-23 14:10 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-23 13:28 [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra
2017-02-23 14:09 ` Peter Zijlstra [this message]
2017-02-23 14:59 ` Peter Zijlstra
2017-02-23 15:09 ` hpa
2017-02-23 15:23 ` Peter Zijlstra
2017-02-23 15:32 ` hpa
2017-02-23 16:03 ` Borislav Petkov
2017-02-23 14:12 ` Josh Poimboeuf
2017-02-23 14:17 ` Borislav Petkov
2017-02-23 14:36 ` Peter Zijlstra
2017-02-23 14:14 ` Arjan van de Ven
2017-02-23 14:57 ` Peter Zijlstra
2017-02-24 7:43 ` Ingo Molnar
2017-02-24 8:31 ` Peter Zijlstra
2017-02-24 9:06 ` hpa
2017-02-24 9:11 ` hpa
2017-02-24 9:15 ` Ingo Molnar
2017-02-24 9:46 ` Borislav Petkov
2017-02-24 9:52 ` H. Peter Anvin
[not found] ` <21ac6e53-2fcd-52e9-e72d-9faf7da14d1e@zytor.com>
2017-02-24 10:41 ` Peter Zijlstra
2017-02-25 10:38 ` Borislav Petkov
2017-02-25 17:55 ` hpa
2017-02-25 19:38 ` Borislav Petkov
2017-02-25 20:04 ` hpa
2017-02-25 20:29 ` Borislav Petkov
2017-02-24 11:16 ` [PATCH -v2] " Peter Zijlstra
2017-02-25 8:19 ` [RFC][PATCH] bug: Add _ONCE logic to report_bug() Peter Zijlstra
2017-02-25 9:18 ` Ingo Molnar
2017-02-25 9:44 ` Peter Zijlstra
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