linux-kernel - Re: [PATCH v9 10/14 UPDATE] perf tools: Check the target platform before assigning unwind methods

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Date:	Tue, 7 Jun 2016 15:06:55 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	He Kuang <hekuang@...wei.com>
Cc:	peterz@...radead.org, mingo@...hat.com,
	alexander.shishkin@...ux.intel.com, jolsa@...hat.com,
	wangnan0@...wei.com, jpoimboe@...hat.com, ak@...ux.intel.com,
	eranian@...gle.com, namhyung@...nel.org, adrian.hunter@...el.com,
	sukadev@...ux.vnet.ibm.com, masami.hiramatsu.pt@...achi.com,
	tumanova@...ux.vnet.ibm.com, kan.liang@...el.com,
	penberg@...nel.org, dsahern@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 10/14 UPDATE] perf tools: Check the target platform
 before assigning unwind methods

Em Sat, Jun 04, 2016 at 05:36:29AM +0000, He Kuang escreveu:
> -int unwind__prepare_access(struct thread *thread)
> +int unwind__prepare_access(struct thread *thread, struct map *map)
>  {
> +	const char *arch;
> +	enum dso_type dso_type;
> +
> +	if (thread->addr_space) {
> +		pr_debug("unwind: thread map already set, dso=%s\n",
> +			 map->dso->name);
> +		return 0;
> +	}
> +
> +	/* env->arch is NULL for live-mode (i.e. perf top) */
> +	if (!thread->mg->machine->env || !thread->mg->machine->env->arch)
> +		return 0;

You can not simply return here, you need to jump to...

> +
> +	dso_type = dso__type(map->dso, thread->mg->machine);
> +	if (dso_type == DSO__TYPE_UNKNOWN)
> +		return 0;
> +
> +	arch = normalize_arch(thread->mg->machine->env->arch);
> +	pr_debug("unwind: target platform=%s\n", arch);
> +

Here:

>  	unwind__register_ops(thread, local_unwind_libunwind_ops);

This way things continue work on, say:

  perf top --call-graph dwarf

or:

  perf trace --call-graph dwarf usleep 1

And also:

  perf test unwind

Will pass, fixing it.
  
>  	return thread->unwind_libunwind_ops->prepare_access(thread);
> diff --git a/tools/perf/util/unwind.h b/tools/perf/util/unwind.h
> index bbd73d9..bf9f593 100644
> --- a/tools/perf/util/unwind.h
> +++ b/tools/perf/util/unwind.h
> @@ -30,11 +30,12 @@ int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
>  /* libunwind specific */
>  #ifdef HAVE_LIBUNWIND_SUPPORT
>  int libunwind__arch_reg_id(int regnum);
> -int unwind__prepare_access(struct thread *thread);
> +int unwind__prepare_access(struct thread *thread, struct map *map);
>  void unwind__flush_access(struct thread *thread);
>  void unwind__finish_access(struct thread *thread);
>  #else
> -static inline int unwind__prepare_access(struct thread *thread __maybe_unused)
> +static inline int unwind__prepare_access(struct thread *thread __maybe_unused,
> +					 struct map *map __maybe_unused)
>  {
>  	return 0;
>  }
> @@ -53,7 +54,8 @@ unwind__get_entries(unwind_entry_cb_t cb __maybe_unused,
>  	return 0;
>  }
>  
> -static inline int unwind__prepare_access(struct thread *thread __maybe_unused)
> +static inline int unwind__prepare_access(struct thread *thread __maybe_unused,
> +					 struct map *map __maybe_unused)
>  {
>  	return 0;
>  }
> -- 
> 1.8.5.2