Messages in this thread | | | Date | Mon, 5 Oct 2009 22:58:28 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH tracing/kprobes v2 1/5] tracing/kprobes: Rename special variables syntax |
| |
On Mon, Oct 05, 2009 at 04:18:39PM -0400, Masami Hiramatsu wrote: > Frederic Weisbecker wrote: >> For the function arguments, I guess we don't need to worry >> anymore about r0, r1, etc... but we can deal with the true var >> name, without any kind of prefixes. > > This depends on ABI, function argument from ABI doesn't need > debuginfo, but it will be unstable on some arch, e.g. x86-32 > with/without asmlinkage. > > Thus, I think that we can just describe where function arguments > will be(e.g. arg0 is ax) as a note for each architecture > in Documents/trace/kprobetrace.txt.
Yeah that may help. Although everyone can look at the calling convention ABI for a given arch but that would still help.
>> What about @return :-) ? > > Hmm, it might conflict with global symbol... Maybe, we can remove this > because retprobe already shows return address in the head of entry.
It won't conflict since "return" is a reserved word and can't then be used as a symbol.
But yeah, if it's an embeded field, we should remove it.
>> What if we take the following: >> >> [Ftrace and perf probe side] >> >> %reg = registers, we can also play with deref and offsets like (%esp), 8(%esp), etc. > > Hmm, on x86-32, sp at intr context is not pointing the top of stack. actually &sp is > the real address of the stack :( > Perhaps, on x86-32, we can translate %sp to stack address in kprobe-tracer.
Oh? You mean in the saved registers while triggering an int 3?
> > %return = return value > > or %retval? :)
Yeah, better!
> >> @return = return addr > > I'd like to remove it, because it's already shown.
Ok.
>> arg(n) = arg number, where n is the number > > How about %N? or just adds a note in documents. >
Hmm, the problem is that %1, %2, etc. is not very self-explainable.
May be %arg1, %arg2, etc.. But would that sound confusing since we have % for registers?
>> [Perf probe only] >> >> var = variable name, global or local, we can deal with shadow issues later >> through variable scope: func_name:var, filename:var, whatever for now >> it's not a problem. Local also includes argument names. > > That's fine to me. :-) >
Great :) Thanks!
| |