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Re: [PATCH -v4 4/9] tracing: add static function tracer support for MIPS

To: rostedt@goodmis.org
Subject: Re: [PATCH -v4 4/9] tracing: add static function tracer support for MIPS
From: Adam Nemet <anemet@caviumnetworks.com>
Date: Thu, 22 Oct 2009 14:29:56 -0700
Cc: David Daney <ddaney@caviumnetworks.com>, wuzhangjin@gmail.com, Richard Sandiford <rdsandiford@googlemail.com>, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, Thomas Gleixner <tglx@linutronix.de>, Ralf Baechle <ralf@linux-mips.org>, Nicholas Mc Guire <der.herr@hofr.at>
In-reply-to: <1256244726.20866.802.camel@gandalf.stny.rr.com>
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Steven Rostedt writes:
> On Thu, 2009-10-22 at 13:30 -0700, Adam Nemet wrote:
> > Also note that for functions invoked via tail call you won't get an exit
> > event.  E.g. if bar is tail-called from foo:
> > 
> >   foo entered
> >   bar entered
> >   foo/bar exited
> > 
> > However, this is not MIPS-specific and you can always disable tail calls
> > with -fno-optimize-sibling-calls.
> 
> The question is, would bar have a _mcount call? So far, we have not had
> any issues with this on either x86 nor PPC.

Yes, bar will have an _mcount call.  The difference is that bar will return to
foo's caller directly rather than to foo first.

Adam

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