linux-kernel - Re: [RFC PATCH 6/6] uprobes/x86: Emulate rip-relative conditional "near" jmp's

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Message-ID: <20140409165042.GE18486@redhat.com>
Date:	Wed, 9 Apr 2014 18:50:42 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Jim Keniston <jkenisto@...ux.vnet.ibm.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <aarapov@...hat.com>,
	David Long <dave.long@...aro.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	"Frank Ch. Eigler" <fche@...hat.com>,
	Jonathan Lebon <jlebon@...hat.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 6/6] uprobes/x86: Emulate rip-relative conditional
	"near" jmp's

On 04/08, Jim Keniston wrote:
>
> On Mon, 2014-04-07 at 16:28 +0200, Oleg Nesterov wrote:
> >
> > It seems that 16bit condi jmp is just 0x0f + short_jump_opc_plus_0x10.
>
> Yes, but the code could use a comment to that effect.  See below.

OK, will do.

> Searching for "jump" in the AMD manual, I see that there are 3 other
> instructions that are essentially conditional branches: loop,
> loope/loopz, and loopne/loopnz.

Yes, I know, Denys already informed me privately ;)

> The offset is always 8 bits.

And thus this series can ignore them. But as I already said, I'll try
to support them later just for completeness.

> BTW, patches 2 and 3 look fine to me.

Great!

Thanks again Jim for your helpful review.

Oleg.

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