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From: Borislav Petkov <bp@alien8.de>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: x86-ml <x86@kernel.org>, Joerg Roedel <jroedel@suse.de>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] Have insn decoder functions return success/failure
Date: Fri, 23 Oct 2020 11:17:55 +0200	[thread overview]
Message-ID: <20201023091755.GA23324@zn.tnic> (raw)
In-Reply-To: <20201022222140.f46e6db1243e05fdd049b504@kernel.org>

On Thu, Oct 22, 2020 at 10:21:40PM +0900, Masami Hiramatsu wrote:
> extern void insn_init(struct insn *insn, const void *kaddr, int buf_len, int x86_64);
> extern void insn_get_prefixes(struct insn *insn);
> extern void insn_get_opcode(struct insn *insn);
> extern void insn_get_modrm(struct insn *insn);
> extern void insn_get_sib(struct insn *insn);
> extern void insn_get_displacement(struct insn *insn);
> extern void insn_get_immediate(struct insn *insn);
> extern void insn_get_length(struct insn *insn);

...

> Ah, so you meant that we don't need such a different insn_get_* APIs,
> but a single insn_decode() API, which will decode all fields.
> (IOW, alias of insn_init() and insn_get_length(), right?)

Yes, so there should be a balance between what one wants to decode:

length, opcodes, etc

vs

when one needs only a certain *single* aspect: sib, length,
displacement, etc.

So if you need a couple of things, you can simply call the insn_decode()
function - I'm reading forward and I like your naming :) - and when
that returns success, you can be sure that struct insn contains all the
fields needed.

Otherwise...

> > If there are specialized uses, you can call some of the insn_get_*
> > helpers if you're not interested in decoding the full insn.
> 
> OK, agreed.

... yes, exactly!

> > But if simply calling insn_decode_insn() would give you everything and
> > that is not that expensive, we can do that - API simplicity.
> 
> I rather like simple "insn_decode()" function, no need to repeat
> insn again.
> 
> int insn_decode(struct insn *insn, const void *kaddr, int buf_len, bool x86_64);

Yap, good.

Ok, seems we agree, lemme poke at this one more time, convert some users
and we can see how it looks like and talk then.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  parent reply	other threads:[~2020-10-23  9:18 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-20 12:02 [RFC] Have insn decoder functions return success/failure Borislav Petkov
2020-10-20 14:27 ` Masami Hiramatsu
2020-10-20 14:37   ` Borislav Petkov
2020-10-21  0:50     ` Masami Hiramatsu
2020-10-21  9:27       ` Borislav Petkov
2020-10-21 14:26         ` Masami Hiramatsu
2020-10-21 16:45           ` Borislav Petkov
2020-10-22  7:31             ` Masami Hiramatsu
2020-10-22  9:30               ` Borislav Petkov
2020-10-22 13:21                 ` Masami Hiramatsu
2020-10-22 17:58                   ` Andy Lutomirski
2020-10-23  9:20                     ` Borislav Petkov
2020-10-23  9:28                     ` Masami Hiramatsu
2020-10-23  9:32                       ` Borislav Petkov
2020-10-23 10:47                         ` Masami Hiramatsu
2020-10-23 23:27                           ` Borislav Petkov
2020-10-24  0:12                             ` Andy Lutomirski
2020-10-24  7:21                               ` Masami Hiramatsu
2020-10-24  8:23                               ` Borislav Petkov
2020-10-24 16:10                                 ` Andy Lutomirski
2020-10-27 13:42                                   ` Borislav Petkov
2020-10-28 11:36                                     ` Masami Hiramatsu
2020-10-24  7:13                             ` Masami Hiramatsu
2020-10-24  8:24                               ` Borislav Petkov
2020-10-29 12:42                             ` Borislav Petkov
2020-10-30  1:24                               ` Masami Hiramatsu
2020-10-30 13:07                                 ` Borislav Petkov
2020-10-23  9:17                   ` Borislav Petkov [this message]
2020-10-22  8:04             ` Peter Zijlstra

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