lkml.org 
[lkml]   [2013]   [Nov]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCHSET 00/13] tracing/uprobes: Add support for more fetch methods (v6)
Date
Hi Oleg and Masami,

On Sat, 9 Nov 2013 16:23:13 +0100, Oleg Nesterov wrote:
> On 11/09, Masami Hiramatsu wrote:
>>
>> In that case, I suggest you to use "@+addr" for the relative address,
>> since that is an offset, isn't that? :)
>
> Agreed, @+addr looks better!

Looks good to me too.

>
>> BTW, it seems that @addr syntax is hard to use for uprobes, because
>> current uprobes is based on a binary, not a process, we cannot specify
>> which process is probed when we define it.
>
> Yes, exactly. That is why we suggest that user-space should pass the
> ip-relative address (actually offset). This should hopefully solve all
> problems with relocations.

Let me clarify what I understand.

For @addr syntax: kernel does no translation and uses given address

For @+addr syntax: user-space uses relative symbol address from a loaded
base address and kernel calculates the base address
using "current->utask->vaddr - tu->offset".

Is that right?

Thanks,
Namhyung


\
 
 \ /
  Last update: 2013-11-12 09:21    [W:1.078 / U:0.080 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site