Re: [PATCH -tip 3/6 V4.1] x86: instruction decorder API

From: Jim Keniston <jkenisto@us.ibm.com>
To: Masami Hiramatsu <mhiramat@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>,
	Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
	Andi Kleen <andi@firstfloor.org>,
	kvm@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	systemtap-ml <systemtap@sources.redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Vegard Nossum <vegard.nossum@gmail.com>,
	Avi Kivity <avi@redhat.com>, Roland McGrath <roland@redhat.com>
Subject: Re: [PATCH -tip 3/6 V4.1] x86: instruction decorder API
Date: Thu, 23 Apr 2009 15:22:32 -0700	[thread overview]
Message-ID: <1240525367.3461.10.camel@dyn9047018094.beaverton.ibm.com> (raw)
In-Reply-To: <49F0A570.8000908@redhat.com>

On Thu, 2009-04-23 at 13:29 -0400, Masami Hiramatsu wrote:
...
> 
> Hmm, maybe, parser can handle "(extra_info)" as a solid keyword.
> so let's define actual format.
> 
> <opcode maps>
> Table: table-name
> Referrer: escamed-name
> opcode: mnemonic|Grp [operand1[,operand2...]] [(extra1)[,(extra2)...] [| 2nd-mnemonic ...]
> opcode: ESC # escaped-name
> 
> <group maps>
> reg: mnemonic ...

For some instruction groups -- e.g., Groups 12, 13, 14 -- the
instruction prefix (66, f2, f3) and the reg field both affect the
instruction type.  And for some x87 instructions, the value of the modrm
byte's rm field also affects the instruction type.  (For others, rm just
selects among the st(0)..st(7) registers, as one might expect.)

Of course, that's all about floating-point instructions, which are of
more interest to uprobes than kprobes. 

Jim