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

Masami Hiramatsu
2009-08-20T16:13:34Z

Frederic Weisbecker wrote:
> 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?

Hmm, it is possible that mawk will fix those bugs and catch up soon,
so, I think checking mawk is not a good idea.
(and since there will be other awk implementations, it's not fair.)

I think what all I can do now is reporting bugs to
mawk and ubuntu people.:-)

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

Thank you for testing!