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

From: Oleg Nesterov
Date: Tue Nov 12 2013 - 13:43:08 EST


Hi Namhyung,

On 11/12, Namhyung Kim wrote:
>
> Let me clarify what I understand.
>
> For @addr syntax: kernel does no translation and uses given address

Yes,

> 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".

Looks right to me.

IOW, when user-space calculates the "addr" for @+ argument, it should
assume that this binary will be mmaped at "NULL" (so that the virtual
address of the probed function is always equal to its offset in the
probed binary).

Masami, Steven, et al, do you agree?

Oleg.

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