linux-kernel - Re: [PATCH 1/2] perf, x86-mm: Add exit-fault tracing

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Message-ID: <20161027083714.GF3568@worktop.programming.kicks-ass.net>
Date:   Thu, 27 Oct 2016 10:37:14 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Alexis Berlemont <alexis.berlemont@...il.com>,
        linux-kernel@...r.kernel.org, mingo@...hat.com,
        alexander.shishkin@...ux.intel.com
Subject: Re: [PATCH 1/2] perf, x86-mm: Add exit-fault tracing

On Wed, Oct 26, 2016 at 04:53:39PM -0200, Arnaldo Carvalho de Melo wrote:

> > > +++ b/arch/x86/mm/fault.c
> > > @@ -1488,6 +1488,7 @@ trace_do_page_fault(struct pt_regs *regs, unsigned long error_code)
> > >  	prev_state = exception_enter();
> > >  	trace_page_fault_entries(address, regs, error_code);
> > >  	__do_page_fault(regs, error_code, address);
> > > +	trace_page_fault_exit(address);
> > 
> > Aside from my general hatred of tracepoint, it bugs me that its not
> > symmetric like the irq vector ones. But I'll leave that to x86 people.
> 
> What is the simmetry problem, you think we should have:

Look at arch/x86/include/asm/trace/irq_vectors.h and

$ git grep "trace.*_VECTOR"

The entry and exit tracepoints are fully symmetric and generate from a
single macro.