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Subject: Re: [PATCH 09/14] perf, x86: use LBR for PEBS IP+1 fixup
From: Peter Zijlstra <peterz@infradead.org>
To: Masami Hiramatsu <mhiramat@redhat.com>
Cc: mingo@elte.hu, linux-kernel@vger.kernel.org, paulus@samba.org,
       eranian@google.com, robert.richter@amd.com, fweisbec@gmail.com,
       Arnaldo Carvalho de Melo <acme@infradead.org>,
       Yanmin Zhang <yanmin_zhang@linux.intel.com>
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References: <20100304140046.596569763@chello.nl>
	 <20100304140100.619375431@chello.nl>  <4B8FDE16.3050403@redhat.com>
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Date: Thu, 04 Mar 2010 18:54:22 +0100
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On Thu, 2010-03-04 at 11:21 -0500, Masami Hiramatsu wrote:
> Peter Zijlstra wrote:

> > +#define perf_misc_flags(regs)				\
> > +({	int misc = 0;					\
> > +	if (user_mode(regs))				\
> > +		misc |= PERF_RECORD_MISC_USER;		\
> > +	else						\
> > +		misc |= PERF_RECORD_MISC_KERNEL;	\
> > +	if (regs->flags & PERF_EFLAGS_EXACT)		\
> > +		misc |= PERF_RECORD_MISC_EXACT;		\
> > +	misc; })
> > +
> > +#define perf_instruction_pointer(regs)	((regs)->ip)
> 
> Hmm, why don't you use instruction_pointer() defined in asm/ptrace.h?
> And I couldn't find any user of this macro in this patch...

perf_instruction_pointer() is used in kernel/perf_event.c, and yeah I
could have used instruction_pointer() but that's yet another wrapper.

Anyway, Yanmin is poking at doing kvm-guest profiling and will likely
rewrite all of the perf_misc() and perf_instruction_pointer() stuff
soon.