linux-kernel - Re: Re: [PATCH perf/core 1/2] [BUGFIX] perf-probe: Fix to handle optimized not-inlined but has no instance

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Date:	Wed, 11 Feb 2015 17:42:20 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc:	Peter Zijlstra <peterz@...radead.org>, namhyung@...nel.org,
	Ingo Molnar <mingo@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Re: [PATCH perf/core 1/2] [BUGFIX] perf-probe: Fix to handle
 optimized not-inlined but has no instance

Em Sun, Feb 08, 2015 at 05:37:08PM +0900, Masami Hiramatsu escreveu:
> (2015/01/30 23:21), Arnaldo Carvalho de Melo wrote:
> > So perhaps I need a 'noinline' _and_ '__sched', so that I have a "optimized
> > no-inline functions which have only function definition but no actual instance
> > at that point"?
> 
> Ok, actually vmalloc_fault is marked as a nokprobe symbol.
> 
> $ grep vmalloc_fault -r arch/x86/
> arch/x86/mm/fault.c:static noinline int vmalloc_fault(unsigned long address)
> arch/x86/mm/fault.c:NOKPROBE_SYMBOL(vmalloc_fault);
> arch/x86/mm/fault.c:static noinline int vmalloc_fault(unsigned long address)
> arch/x86/mm/fault.c:NOKPROBE_SYMBOL(vmalloc_fault);
> arch/x86/mm/fault.c:                    if (vmalloc_fault(address) >= 0)
> 
> All the symbols which marked by NOKPROBE_SYMBOL macro can not be
> kprobed. And we now have <debugfs>/kprobes/blacklist special file

Ok!

> to get all nokprobe symbols.

> I'll make another perf-probe patch which looks the blacklist before
> trying define new events.

Ok, that will help, improving the error messages is a big priority.

- Arnaldo
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