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

Frederic Weisbecker
2009-08-20T18:07:45Z

On Thu, Aug 20, 2009 at 12:16:05PM -0400, Masami Hiramatsu wrote:
> 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.:-)

Yeah, but without your tip I couldn't be able to find the origin
before some time.
And the kernel couldn't build anyway.

At least we should do something with this version of mawk.

>>
>> Anyway that works fine now with gawk, thanks!
>> All your patches build well :-)
>
> Thank you for testing!
>
> --
> Masami Hiramatsu
>
> Software Engineer
> Hitachi Computer Products (America), Inc.
> Software Solutions Division
>
> e-mail: mhiramat@redhat.com
>