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Groups > linux.kernel > #1586935
| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] x86: Implement __WARN using UD0 |
| Date | 2017-02-23 16:00 +0100 |
| Message-ID | <te329-2EY-15@gated-at.bofh.it> (permalink) |
| References | <te1D4-1LK-9@gated-at.bofh.it> <te2pr-2oI-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, Feb 23, 2017 at 03:09:29PM +0100, Peter Zijlstra wrote:
> 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?
N/m, as Josh said, they're listed in the latest SDM (Dec 2016) and that
lists UD1 /r, so 3 bytes.
This means binutils decodes it wrong.
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[PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-23 14:30 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Arjan van de Ven <arjan@linux.intel.com> - 2017-02-23 15:20 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-23 16:00 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Ingo Molnar <mingo@kernel.org> - 2017-02-24 09:00 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-24 09:40 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Ingo Molnar <mingo@kernel.org> - 2017-02-24 10:20 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Borislav Petkov <bp@alien8.de> - 2017-02-24 10:50 +0100
Re: [PATCH] x86: Implement __WARN using UD0 "H. Peter Anvin" <hpa@zytor.com> - 2017-02-24 12:50 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-24 12:50 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Borislav Petkov <bp@alien8.de> - 2017-02-25 11:50 +0100
Re: [PATCH] x86: Implement __WARN using UD0 hpa@zytor.com - 2017-02-25 19:00 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Borislav Petkov <bp@alien8.de> - 2017-02-25 20:40 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Borislav Petkov <bp@alien8.de> - 2017-02-25 21:40 +0100
Re: [PATCH] x86: Implement __WARN using UD0 hpa@zytor.com - 2017-02-25 21:50 +0100
Re: [PATCH] x86: Implement __WARN using UD0 hpa@zytor.com - 2017-02-24 10:20 +0100
Re: [PATCH] x86: Implement __WARN using UD0 hpa@zytor.com - 2017-02-24 10:50 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-23 15:20 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-23 16:00 +0100
Re: [PATCH] x86: Implement __WARN using UD0 hpa@zytor.com - 2017-02-23 16:20 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-23 16:30 +0100
Re: [PATCH] x86: Implement __WARN using UD0 hpa@zytor.com - 2017-02-23 16:40 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Borislav Petkov <bp@alien8.de> - 2017-02-23 17:10 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Josh Poimboeuf <jpoimboe@redhat.com> - 2017-02-23 15:20 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Borislav Petkov <bp@alien8.de> - 2017-02-23 15:30 +0100
Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-23 15:40 +0100
[PATCH -v2] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-24 12:20 +0100
[RFC][PATCH] bug: Add _ONCE logic to report_bug() Peter Zijlstra <peterz@infradead.org> - 2017-02-25 10:10 +0100
Re: [RFC][PATCH] bug: Add _ONCE logic to report_bug() Ingo Molnar <mingo@kernel.org> - 2017-02-25 10:20 +0100
Re: [RFC][PATCH] bug: Add _ONCE logic to report_bug() Peter Zijlstra <peterz@infradead.org> - 2017-02-25 11:50 +0100
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