Messages in this thread | | | From | Namhyung Kim <> | Subject | Re: [PATCHSET 00/13] tracing/uprobes: Add support for more fetch methods (v6) | Date | Tue, 12 Nov 2013 17:00:01 +0900 |
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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
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