Hi Namhyung,This seems really interesting and is what I am looking for. Can it capture all function entries/exits? I mean does it fully handle variable instruction sizes in dynamic mode? In any case, thanks! and I hope that it becomes stable as soon as possible, so that everyone can use it.
Regards. On 2020-07-16 05:34, Namhyung Kim wrote:
Hi all,On Thu, Jul 16, 2020 at 3:28 AM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:On Wed, 15 Jul 2020 20:37:16 +0430 ahmadkhorrami <ahmadkhorrami@xxxxxxxx> wrote: Hi, What is the most efficient way to capture occurrence of a function call/return of a binary program in userspace? It seems the answer is Uprobes. 1) Am I right? But Uprobes use "int" instruction which leads to a switch into kernel mode. 2) Wouldn't it be better to avoid this transition? I'm looking forward to your reply and will be happy to read your opinions. Regards. Hi, I believe LTTng has utilities that can help you trace user space programs. I think there's also a users ftrace like utility that Namhyung was working on. But I don't know where in the development that is.
It's in https://github.com/namhyung/uftraceBasically it also requires recompilation to add mcount calls for each function.
But it now also supports dynamic tracing without any recompilation.. :) It's still experimental and has some limitation, but the idea is to copyfirst 5 bytes (on x86_64) somewhere and replace it to a call instruction.
Thanks Namhyung
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