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


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 âinat_get_opcode_attributeâ:
arch/x86/lib/inat.c:29: erreur: âinat_primary_tableâ 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!


--
Masami Hiramatsu

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

e-mail: mhiramat@redhat.com


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