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

Frederic Weisbecker
2009-08-20T20:14:40Z

On Thu, Aug 20, 2009 at 03:01:25PM -0400, Masami Hiramatsu wrote:
> Frederic Weisbecker wrote:
>> 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.
>
> Hm, indeed.
> Maybe, we can run additional sanity check script before using
> awk, like this;
>
> ---
> res=`echo a | $AWK '/[[:lower:]]+/{print "OK"}'`
> [ "$res" != "OK" ] && exit 1
>
> res=`$AWK 'BEGIN {printf("%x", 0)}'`
> [ "$res" != "0" ] && exit 1
>
> exit 0
> ---
>
> Thanks,
>

Yeah, that looks good.

Thanks.