Messages in this thread | | | Date | Mon, 05 Oct 2009 17:11:05 -0400 | From | Masami Hiramatsu <> | Subject | Re: [PATCH tracing/kprobes v2 1/5] tracing/kprobes: Rename special variables syntax |
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Frederic Weisbecker wrote: > 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?
Yes, interrupt/exception handlers don't save sp on x86-32.
>>> 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?
As I sent right now, how about %argumentN ? it will not conflict with register names...
Thank you,
-- Masami Hiramatsu
Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division
e-mail: mhiramat@redhat.com
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