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

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Date:	Thu, 20 Aug 2009 11:03:40 -0400
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Frederic Weisbecker <fweisbec@...il.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

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

> 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
$ 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,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@...hat.com

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