linux-kernel - Re: [PATCH -tip v14 01/12] x86: instruction decoder API

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Message-ID: <20090820152549.GD6389@nowhere>
Date:	Thu, 20 Aug 2009 17:25:51 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Masami Hiramatsu <mhiramat@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>,
	lkml <linux-kernel@...r.kernel.org>,
	systemtap <systemtap@...rces.redhat.com>,
	kvm <kvm@...r.kernel.org>,
	DLE <dle-develop@...ts.sourceforge.net>,
	Jim Keniston <jkenisto@...ibm.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Avi Kivity <avi@...hat.com>, Andi Kleen <ak@...ux.intel.com>,
	Christoph Hellwig <hch@...radead.org>,
	"Frank Ch. Eigler" <fche@...hat.com>,
	Jason Baron <jbaron@...hat.com>,
	"K.Prasad" <prasad@...ux.vnet.ibm.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Li Zefan <lizf@...fujitsu.com>,
	PrzemysławPawełczyk <przemyslaw@...elczyk.it>,
	Roland McGrath <roland@...hat.com>,
	Sam Ravnborg <sam@...nborg.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Tom Zanussi <tzanussi@...il.com>,
	Vegard Nossum <vegard.nossum@...il.com>
Subject: Re: [PATCH -tip v14 01/12] x86: instruction decoder API

On Thu, Aug 20, 2009 at 11:03:40AM -0400, Masami Hiramatsu wrote:
> Frederic Weisbecker wrote:
>> On Thu, Aug 20, 2009 at 01:42:31AM +0200, Frederic Weisbecker wrote:
>>> On Thu, Aug 13, 2009 at 04:34:13PM -0400, Masami Hiramatsu wrote:
>>>> Add x86 instruction decoder to arch-specific libraries. This decoder
>>>> can decode x86 instructions used in kernel into prefix, opcode, modrm,
>>>> sib, displacement and immediates. This can also show the length of
>>>> instructions.
>>>>
>>>> This version introduces instruction attributes for decoding instructions.
>>>> The instruction attribute tables are generated from the opcode map file
>>>> (x86-opcode-map.txt) by the generator script(gen-insn-attr-x86.awk).
>>>>
>>>> Currently, the opcode maps are based on opcode maps in Intel(R) 64 and
>>>> IA-32 Architectures Software Developers Manual Vol.2: Appendix.A,
>>>> and consist of below two types of opcode tables.
>>>>
>>>> 1-byte/2-bytes/3-bytes opcodes, which has 256 elements, are
>>>> written as below;
>>>>
>>>>   Table: table-name
>>>>   Referrer: escaped-name
>>>>   opcode: mnemonic|GrpXXX [operand1[,operand2...]] [(extra1)[,(extra2)...] [| 2nd-mnemonic ...]
>>>>    (or)
>>>>   opcode: escape # escaped-name
>>>>   EndTable
>>>>
>>>> Group opcodes, which has 8 elements, are written as below;
>>>>
>>>>   GrpTable: GrpXXX
>>>>   reg:  mnemonic [operand1[,operand2...]] [(extra1)[,(extra2)...] [| 2nd-mnemonic ...]
>>>>   EndTable
>>>>
>>>> These opcode maps include a few SSE and FP opcodes (for setup), because
>>>> those opcodes are used in the kernel.
>>>>
>>>
>>>
>>> I'm getting the following build error on an old K7 box:
>>>
>>> arch/x86/lib/inat.c: In function ‘inat_get_opcode_attribute’:
>>> arch/x86/lib/inat.c:29: erreur: ‘inat_primary_table’ undeclared (first use in this function)
>>> arch/x86/lib/inat.c:29: erreur: (Each undeclared identifier is reported only once
>>> arch/x86/lib/inat.c:29: erreur: for each function it appears in.)
>>>
>>>
>>> I've attached my config. I haven't such problem on a dual x86-64 box.
>>
>>
>> Actually I have the same problem in x86-64
>> The content of my arch/x86/lib/inat-tables.c:
>>
>> /* x86 opcode map generated from x86-opcode-map.txt */
>> /* Do not change this code. */
>> /* Table: one byte opcode */
>> /* Escape opcode map array */
>> const insn_attr_t const *inat_escape_tables[INAT_ESC_MAX + 1][INAT_LPREFIX_MAX + 1] = {
>> };
>>
>> /* Group opcode map array */
>> const insn_attr_t const *inat_group_tables[INAT_GRP_MAX + 1][INAT_LPREFIX_MAX + 1] = {
>> };
>>
>>
>> I guess there is a problem with the generation of this file.
>
> Aah, you may use mawk on Ubuntu 9.04, right?
> If so, unfortunately, mawk is still under development.
>
> http://invisible-island.net/mawk/CHANGES



Aargh...


>> 20090727
>> 	add check/fix to prevent gsub from recurring to modify on a substring
>> 	of the current line when the regular expression is anchored to the
>> 	beginning of the line; fixes gawk's anchgsub testcase.
>>
>> 	add check for implicit concatenation mistaken for exponent; fixes
>> 	gawk's hex testcase.
>>
>> 	add character-classes to built-in regular expressions.
>         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Look, this means we can't use char-class expressions like
> [:lower:] until this version...
>
> And I've found another bug in mawk-1.3.3-20090728(the latest one).
> it almost works, but;
>
> $ mawk 'BEGIN {printf("0x%x\n", 0)}'
> 0x1


Ouch, indeed.



> $ gawk 'BEGIN {printf("0x%x\n", 0)}'
> 0x0
>
> This bug skips an array element index 0x0 in inat-tables.c :(
>
> So, I recommend you to install gawk instead mawk until that
> supports all posix-awk features, since I don't think it is
> good idea to avoid all those bugs which depends on
> implementation (not specification).
>
>
> Thank you,



Yeah, indeed. May be add a warning (or build error) in case the user uses
mawk?

Anyway that works fine now with gawk, thanks!
All your patches build well :-)


>
> -- 
> Masami Hiramatsu
>
> Software Engineer
> Hitachi Computer Products (America), Inc.
> Software Solutions Division
>
> e-mail: mhiramat@...hat.com
>

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