perf parse: Copy string to perf_evsel_config_term

perf with CoreSight fails to record trace data with command:

  perf record -e cs_etm/@tmc_etr0/u --per-thread ls
  failed to set sink "" on event cs_etm/@tmc_etr0/u with 21 (Is a
  directory)/perf/

This failure is root caused with the commit 1dc9255 ("perf
parse: Add a deep delete for parse event terms").

The log shows, cs_etm fails to parse the sink attribution; cs_etm event
relies on the event configuration to pass sink name, but the event
specific configuration data cannot be passed properly with flow:

  get_config_terms()
    ADD_CONFIG_TERM(DRV_CFG, term->val.str);
      __t->val.str = term->val.str;
        `> __t->val.str is assigned to term->val.str;

  parse_events_terms__purge()
    parse_events_term__delete()
      zfree(&term->val.str);
        `> term->val.str is freed and assigned to NULL pointer;

  cs_etm_set_sink_attr()
    sink = __t->val.str;
      `> sink string has been freed.

To fix this issue, in the function get_config_terms(), this patch
changes to use strdup() for allocation a new duplicate string rather
than directly assignment string pointer.

This patch addes a new field 'free_str' in the data structure
perf_evsel_config_term; 'free_str' is set to true when the union is used
as a string pointer; thus it can tell perf_evsel__free_config_terms() to
free the string.

Fixes: 1dc9255 ("perf parse: Add a deep delete for parse event terms")
Suggested-by: Jiri Olsa <[email protected]>
Signed-off-by: Leo Yan <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Mathieu Poirier <[email protected]>
Cc: Mike Leach <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Suzuki Poulouse <[email protected]>
Cc: [email protected]
Link: http://lore.kernel.org/lkml/[email protected]
[ Use zfree() in perf_evsel__free_config_terms ]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

:#	modified:   tools/perf/util/evsel_config.h

Author: Leo Yan

tools/perf/util/evsel.c

@@ -1265,6 +1265,8 @@ static void perf_evsel__free_config_terms(struct evsel *evsel)
 
 	list_for_each_entry_safe(term, h, &evsel->config_terms, list) {
 		list_del_init(&term->list);
+		if (term->free_str)
+			zfree(&term->val.str);
 		free(term);
 	}
 }

tools/perf/util/evsel_config.h

@@ -32,6 +32,7 @@ enum evsel_term_type {
 struct perf_evsel_config_term {
 	struct list_head      list;
 	enum evsel_term_type  type;
+	bool		      free_str;
 	union {
 		u64	      period;
 		u64	      freq;

tools/perf/util/parse-events.c

@@ -1240,7 +1240,12 @@ do {								\
 #define ADD_CONFIG_TERM_STR(__type, __val)			\
 do {								\
 	ADD_CONFIG_TERM(__type);				\
-	__t->val.str = __val;					\
+	__t->val.str = strdup(__val);				\
+	if (!__t->val.str) {					\
+		zfree(&__t);					\
+		return -ENOMEM;					\
+	}							\
+	__t->free_str = true;					\
 } while (0)
 
 	struct parse_events_term *term;