Re: [PATCH V7 04/25] perf tools: Add support for AUX area recording

[Jiri Olsa <jolsa@redhat.com>]

On Tue, Mar 31, 2015 at 02:38:33PM +0300, Adrian Hunter wrote:
> Add support for reading from the AUX area
> tracing mmap and synthesizing AUX area
> tracing events.
> 
> This patch introduces an abstraction for recording
> AUX area data.  Recording is initialized
> by auxtrace_record__init() which is a weak function
> to be implemented by the architecture to provide
> recording callbacks.  Recording is mainly handled
> by auxtrace_mmap__read() and
> perf_event__synthesize_auxtrace() but there are
> callbacks for miscellaneous needs including
> validating and processing user options, populating
> private data in auxtrace_info_event, and freeing
> the structure when finished.
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>

Acked-by: Jiri Olsa <jolsa@kernel.org>

> ---
>  tools/perf/perf.h          |   2 +
>  tools/perf/util/auxtrace.c | 176 +++++++++++++++++++++++++++++++++++++++++++++
>  tools/perf/util/auxtrace.h |  56 ++++++++++++++-
>  tools/perf/util/record.c   |  11 ++-
>  4 files changed, 243 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/perf.h b/tools/perf/perf.h
> index c38a085..95a3bd4 100644
> --- a/tools/perf/perf.h
> +++ b/tools/perf/perf.h
> @@ -54,8 +54,10 @@ struct record_opts {
>  	bool	     period;
>  	bool	     sample_intr_regs;
>  	bool	     running_time;
> +	bool	     full_auxtrace;
>  	unsigned int freq;
>  	unsigned int mmap_pages;
> +	unsigned int auxtrace_mmap_pages;
>  	unsigned int user_freq;
>  	u64          branch_stack;
>  	u64	     default_interval;
> diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
> index 75419a5..b3ed200 100644
> --- a/tools/perf/util/auxtrace.c
> +++ b/tools/perf/util/auxtrace.c
> @@ -23,6 +23,10 @@
>  #include <linux/bitops.h>
>  #include <linux/log2.h>
>  
> +#include <stdlib.h>
> +#include <string.h>
> +#include <errno.h>
> +
>  #include "../perf.h"
>  #include "util.h"
>  #include "evlist.h"
> @@ -31,6 +35,9 @@
>  #include "asm/bug.h"
>  #include "auxtrace.h"
>  
> +#include "event.h"
> +#include "debug.h"
> +
>  int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,
>  			struct auxtrace_mmap_params *mp,
>  			void *userpg, int fd)
> @@ -106,3 +113,172 @@ void auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp,
>  		mp->tid = evlist->threads->map[idx];
>  	}
>  }
> +
> +size_t auxtrace_record__info_priv_size(struct auxtrace_record *itr)
> +{
> +	if (itr)
> +		return itr->info_priv_size(itr);
> +	return 0;
> +}
> +
> +static int auxtrace_not_supported(void)
> +{
> +	pr_err("AUX area tracing is not supported on this architecture\n");
> +	return -EINVAL;
> +}
> +
> +int auxtrace_record__info_fill(struct auxtrace_record *itr,
> +			       struct perf_session *session,
> +			       struct auxtrace_info_event *auxtrace_info,
> +			       size_t priv_size)
> +{
> +	if (itr)
> +		return itr->info_fill(itr, session, auxtrace_info, priv_size);
> +	return auxtrace_not_supported();
> +}
> +
> +void auxtrace_record__free(struct auxtrace_record *itr)
> +{
> +	if (itr)
> +		itr->free(itr);
> +}
> +
> +int auxtrace_record__options(struct auxtrace_record *itr,
> +			     struct perf_evlist *evlist,
> +			     struct record_opts *opts)
> +{
> +	if (itr)
> +		return itr->recording_options(itr, evlist, opts);
> +	return 0;
> +}
> +
> +u64 auxtrace_record__reference(struct auxtrace_record *itr)
> +{
> +	if (itr)
> +		return itr->reference(itr);
> +	return 0;
> +}
> +
> +struct auxtrace_record *__weak
> +auxtrace_record__init(struct perf_evlist *evlist __maybe_unused, int *err)
> +{
> +	*err = 0;
> +	return NULL;
> +}
> +
> +int perf_event__synthesize_auxtrace_info(struct auxtrace_record *itr,
> +					 struct perf_tool *tool,
> +					 struct perf_session *session,
> +					 perf_event__handler_t process)
> +{
> +	union perf_event *ev;
> +	size_t priv_size;
> +	int err;
> +
> +	pr_debug2("Synthesizing auxtrace information\n");
> +	priv_size = auxtrace_record__info_priv_size(itr);
> +	ev = zalloc(sizeof(struct auxtrace_info_event) + priv_size);
> +	if (!ev)
> +		return -ENOMEM;
> +
> +	ev->auxtrace_info.header.type = PERF_RECORD_AUXTRACE_INFO;
> +	ev->auxtrace_info.header.size = sizeof(struct auxtrace_info_event) +
> +					priv_size;
> +	err = auxtrace_record__info_fill(itr, session, &ev->auxtrace_info,
> +					 priv_size);
> +	if (err)
> +		goto out_free;
> +
> +	err = process(tool, ev, NULL, NULL);
> +out_free:
> +	free(ev);
> +	return err;
> +}
> +
> +int auxtrace_mmap__read(struct auxtrace_mmap *mm, struct auxtrace_record *itr,
> +			struct perf_tool *tool, process_auxtrace_t fn)
> +{
> +	u64 head = auxtrace_mmap__read_head(mm);
> +	u64 old = mm->prev, offset, ref;
> +	unsigned char *data = mm->base;
> +	size_t size, head_off, old_off, len1, len2, padding;
> +	union perf_event ev;
> +	void *data1, *data2;
> +
> +	if (old == head)
> +		return 0;
> +
> +	pr_debug3("auxtrace idx %d old %#"PRIx64" head %#"PRIx64" diff %#"PRIx64"\n",
> +		  mm->idx, old, head, head - old);
> +
> +	if (mm->mask) {
> +		head_off = head & mm->mask;
> +		old_off = old & mm->mask;
> +	} else {
> +		head_off = head % mm->len;
> +		old_off = old % mm->len;
> +	}
> +
> +	if (head_off > old_off)
> +		size = head_off - old_off;
> +	else
> +		size = mm->len - (old_off - head_off);
> +
> +	ref = auxtrace_record__reference(itr);
> +
> +	if (head > old || size <= head || mm->mask) {
> +		offset = head - size;
> +	} else {
> +		/*
> +		 * When the buffer size is not a power of 2, 'head' wraps at the
> +		 * highest multiple of the buffer size, so we have to subtract
> +		 * the remainder here.
> +		 */
> +		u64 rem = (0ULL - mm->len) % mm->len;
> +
> +		offset = head - size - rem;
> +	}
> +
> +	if (size > head_off) {
> +		len1 = size - head_off;
> +		data1 = &data[mm->len - len1];
> +		len2 = head_off;
> +		data2 = &data[0];
> +	} else {
> +		len1 = size;
> +		data1 = &data[head_off - len1];
> +		len2 = 0;
> +		data2 = NULL;
> +	}
> +
> +	/* padding must be written by fn() e.g. record__process_auxtrace() */
> +	padding = size & 7;
> +	if (padding)
> +		padding = 8 - padding;
> +
> +	memset(&ev, 0, sizeof(ev));
> +	ev.auxtrace.header.type = PERF_RECORD_AUXTRACE;
> +	ev.auxtrace.header.size = sizeof(ev.auxtrace);
> +	ev.auxtrace.size = size + padding;
> +	ev.auxtrace.offset = offset;
> +	ev.auxtrace.reference = ref;
> +	ev.auxtrace.idx = mm->idx;
> +	ev.auxtrace.tid = mm->tid;
> +	ev.auxtrace.cpu = mm->cpu;
> +
> +	if (fn(tool, &ev, data1, len1, data2, len2))
> +		return -1;
> +
> +	mm->prev = head;
> +
> +	auxtrace_mmap__write_tail(mm, head);
> +	if (itr->read_finish) {
> +		int err;
> +
> +		err = itr->read_finish(itr, mm->idx);
> +		if (err < 0)
> +			return err;
> +	}
> +
> +	return 1;
> +}
> diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
> index 735ca2a..e00f426 100644
> --- a/tools/perf/util/auxtrace.h
> +++ b/tools/perf/util/auxtrace.h
> @@ -18,13 +18,18 @@
>  
>  #include <sys/types.h>
>  #include <stdbool.h>
> -
> +#include <stddef.h>
>  #include <linux/perf_event.h>
>  #include <linux/types.h>
>  
>  #include "../perf.h"
>  
> +union perf_event;
> +struct perf_session;
>  struct perf_evlist;
> +struct perf_tool;
> +struct record_opts;
> +struct auxtrace_info_event;
>  
>  /**
>   * struct auxtrace_mmap - records an mmap of the auxtrace buffer.
> @@ -70,6 +75,29 @@ struct auxtrace_mmap_params {
>  	int		cpu;
>  };
>  
> +/**
> + * struct auxtrace_record - callbacks for recording AUX area data.
> + * @recording_options: validate and process recording options
> + * @info_priv_size: return the size of the private data in auxtrace_info_event
> + * @info_fill: fill-in the private data in auxtrace_info_event
> + * @free: free this auxtrace record structure
> + * @reference: provide a 64-bit reference number for auxtrace_event
> + * @read_finish: called after reading from an auxtrace mmap
> + */
> +struct auxtrace_record {
> +	int (*recording_options)(struct auxtrace_record *itr,
> +				 struct perf_evlist *evlist,
> +				 struct record_opts *opts);
> +	size_t (*info_priv_size)(struct auxtrace_record *itr);
> +	int (*info_fill)(struct auxtrace_record *itr,
> +			 struct perf_session *session,
> +			 struct auxtrace_info_event *auxtrace_info,
> +			 size_t priv_size);
> +	void (*free)(struct auxtrace_record *itr);
> +	u64 (*reference)(struct auxtrace_record *itr);
> +	int (*read_finish)(struct auxtrace_record *itr, int idx);
> +};
> +
>  static inline u64 auxtrace_mmap__read_head(struct auxtrace_mmap *mm __maybe_unused)
>  {
>  	/* Not yet implemented */
> @@ -94,4 +122,30 @@ void auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp,
>  				   struct perf_evlist *evlist, int idx,
>  				   bool per_cpu);
>  
> +typedef int (*process_auxtrace_t)(struct perf_tool *tool,
> +				  union perf_event *event, void *data1,
> +				  size_t len1, void *data2, size_t len2);
> +
> +int auxtrace_mmap__read(struct auxtrace_mmap *mm, struct auxtrace_record *itr,
> +			struct perf_tool *tool, process_auxtrace_t fn);
> +
> +struct auxtrace_record *auxtrace_record__init(struct perf_evlist *evlist,
> +					      int *err);
> +
> +int auxtrace_record__options(struct auxtrace_record *itr,
> +			     struct perf_evlist *evlist,
> +			     struct record_opts *opts);
> +size_t auxtrace_record__info_priv_size(struct auxtrace_record *itr);
> +int auxtrace_record__info_fill(struct auxtrace_record *itr,
> +			       struct perf_session *session,
> +			       struct auxtrace_info_event *auxtrace_info,
> +			       size_t priv_size);
> +void auxtrace_record__free(struct auxtrace_record *itr);
> +u64 auxtrace_record__reference(struct auxtrace_record *itr);
> +
> +int perf_event__synthesize_auxtrace_info(struct auxtrace_record *itr,
> +					 struct perf_tool *tool,
> +					 struct perf_session *session,
> +					 perf_event__handler_t process);
> +
>  #endif
> diff --git a/tools/perf/util/record.c b/tools/perf/util/record.c
> index 8acd0df..0ccfa49 100644
> --- a/tools/perf/util/record.c
> +++ b/tools/perf/util/record.c
> @@ -119,7 +119,16 @@ void perf_evlist__config(struct perf_evlist *evlist, struct record_opts *opts)
>  			evsel->attr.comm_exec = 1;
>  	}
>  
> -	if (evlist->nr_entries > 1) {
> +	if (opts->full_auxtrace) {
> +		/*
> +		 * Need to be able to synthesize and parse selected events with
> +		 * arbitrary sample types, which requires always being able to
> +		 * match the id.
> +		 */
> +		use_sample_identifier = perf_can_sample_identifier();
> +		evlist__for_each(evlist, evsel)
> +			perf_evsel__set_sample_id(evsel, use_sample_identifier);
> +	} else if (evlist->nr_entries > 1) {
>  		struct perf_evsel *first = perf_evlist__first(evlist);
>  
>  		evlist__for_each(evlist, evsel) {
> -- 
> 1.9.1
>