Re: [PATCHSET 00/13] tracing/uprobes: Add support for more fetch methods (v6)

[Namhyung Kim]

On Mon, 4 Nov 2013 16:51:31 +0100, Oleg Nesterov wrote:
> On 11/04, Namhyung Kim wrote:
>> On Mon, 04 Nov 2013 17:46:41 +0900, Namhyung Kim wrote:
>> > On Sat, 2 Nov 2013 16:54:58 +0100, Oleg Nesterov wrote:
>> >> - this only allows to read the data from the same binary.
>> >
>> > Right.  This is also an unnecessary restriction.  We should be able to
>> > access data in other binary.
>>
>> Hmm.. I guess this gonna be not simple
>
> Yes ;)
>
> - perhaps it can only be
>> supported for per-process uprobe with known virtual addresses?
>
> "Known" is very limited. Even in the simplest case (like your test-case
> from from 0/13), you simply can't know the address of "int glob" if you
> compile it with "-pie -fPIC".
>
> As for other binaries (say libc) the problem is even worse, and
> randomize_va_space adds even more pain.

Hmm.. right.  We should deal with relative addresses from the base
mapping address of a binary.

>
> But in any case, I strongly believe that it doesn't make any sense to
> rely on tu->inode in get_user_vaddr().

I'll think about it more.

Thanks,
Namhyung
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