Re: [PATCH 04/14] perf tools: Add fake pmu support

Ian Rogers
2020-06-01T07:22:46Z

On Sun, May 24, 2020 at 3:42 PM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Adding the way to create pmu event without the actual
> PMU being in place. This way we can test metrics defined
> for any processors.
>
> The interface is to define fake_pmu in struct parse_events_state
> data. It will be used only in tests via special interface
> function added in following changes.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> tools/perf/util/parse-events.c | 14 ++++++++++---
> tools/perf/util/parse-events.h | 3 ++-
> tools/perf/util/parse-events.l | 8 ++++++--
> tools/perf/util/parse-events.y | 37 ++++++++++++++++++++++++++++++++--
> 4 files changed, 54 insertions(+), 8 deletions(-)
>
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index 27b8e49d690e..8304f9b6e6be 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -1415,6 +1415,7 @@ int parse_events_add_pmu(struct parse_events_state *parse_state,
> bool auto_merge_stats,
> bool use_alias)
> {
> + bool is_fake = parse_state->fake_pmu;
> struct perf_event_attr attr;
> struct perf_pmu_info info;
> struct perf_pmu *pmu;
> @@ -1436,7 +1437,14 @@ int parse_events_add_pmu(struct parse_events_state *parse_state,
> fprintf(stderr, "' that may result in non-fatal errors\n");
> }
>
> - pmu = perf_pmu__find(name);
> + if (is_fake) {
> + static struct perf_pmu fake_pmu = { };
> +
> + pmu = &fake_pmu;
> + } else {
> + pmu = perf_pmu__find(name);
> + }
> +
> if (!pmu) {
> char *err_str;
>
> @@ -1469,7 +1477,7 @@ int parse_events_add_pmu(struct parse_events_state *parse_state,
> }
> }
>
> - if (perf_pmu__check_alias(pmu, head_config, &info))
> + if (!is_fake && perf_pmu__check_alias(pmu, head_config, &info))
> return -EINVAL;
>
> if (verbose > 1) {
> @@ -1502,7 +1510,7 @@ int parse_events_add_pmu(struct parse_events_state *parse_state,
> if (pmu->default_config && get_config_chgs(pmu, head_config, &config_terms))
> return -ENOMEM;
>
> - if (perf_pmu__config(pmu, &attr, head_config, parse_state->error)) {
> + if (!is_fake && perf_pmu__config(pmu, &attr, head_config, parse_state->error)) {
> struct evsel_config_term *pos, *tmp;
>
> list_for_each_entry_safe(pos, tmp, &config_terms, list) {
> diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
> index d60510e0609f..963b0ea6c448 100644
> --- a/tools/perf/util/parse-events.h
> +++ b/tools/perf/util/parse-events.h
> @@ -126,9 +126,10 @@ struct parse_events_state {
> int idx;
> int nr_groups;
> struct parse_events_error *error;
> - struct evlist *evlist;
> + struct evlist *evlist;
> struct list_head *terms;
> int stoken;
> + bool fake_pmu;
> };
>
> void parse_events__handle_error(struct parse_events_error *err, int idx,
> diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
> index 002802e17059..56912c9641f5 100644
> --- a/tools/perf/util/parse-events.l
> +++ b/tools/perf/util/parse-events.l
> @@ -129,12 +129,16 @@ do { \
> yyless(0); \
> } while (0)
>
> -static int pmu_str_check(yyscan_t scanner)
> +static int pmu_str_check(yyscan_t scanner, struct parse_events_state *parse_state)
> {
> YYSTYPE *yylval = parse_events_get_lval(scanner);
> char *text = parse_events_get_text(scanner);
>
> yylval->str = strdup(text);
> +
> + if (parse_state->fake_pmu)
> + return PE_PMU_EVENT_FAKE;
> +
> switch (perf_pmu__parse_check(text)) {
> case PMU_EVENT_SYMBOL_PREFIX:
> return PE_PMU_EVENT_PRE;
> @@ -376,7 +380,7 @@ r{num_raw_hex} { return raw(yyscanner); }
> {modifier_event} { return str(yyscanner, PE_MODIFIER_EVENT); }
> {bpf_object} { if (!isbpf(yyscanner)) { USER_REJECT }; return str(yyscanner, PE_BPF_OBJECT); }
> {bpf_source} { if (!isbpf(yyscanner)) { USER_REJECT }; return str(yyscanner, PE_BPF_SOURCE); }
> -{name} { return pmu_str_check(yyscanner); }
> +{name} { return pmu_str_check(yyscanner, _parse_state); }
> {name_tag} { return str(yyscanner, PE_NAME); }
> "/" { BEGIN(config); return '/'; }
> - { return '-'; }
> diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
> index c4ca932d092d..d1b04b8d81ea 100644
> --- a/tools/perf/util/parse-events.y
> +++ b/tools/perf/util/parse-events.y
> @@ -69,7 +69,7 @@ static void inc_group_count(struct list_head *list,
> %token PE_NAME_CACHE_TYPE PE_NAME_CACHE_OP_RESULT
> %token PE_PREFIX_MEM PE_PREFIX_RAW PE_PREFIX_GROUP
> %token PE_ERROR
> -%token PE_PMU_EVENT_PRE PE_PMU_EVENT_SUF PE_KERNEL_PMU_EVENT
> +%token PE_PMU_EVENT_PRE PE_PMU_EVENT_SUF PE_KERNEL_PMU_EVENT PE_PMU_EVENT_FAKE
> %token PE_ARRAY_ALL PE_ARRAY_RANGE
> %token PE_DRV_CFG_TERM
> %type <num> PE_VALUE
> @@ -87,7 +87,7 @@ static void inc_group_count(struct list_head *list,
> %type <str> PE_MODIFIER_EVENT
> %type <str> PE_MODIFIER_BP
> %type <str> PE_EVENT_NAME
> -%type <str> PE_PMU_EVENT_PRE PE_PMU_EVENT_SUF PE_KERNEL_PMU_EVENT
> +%type <str> PE_PMU_EVENT_PRE PE_PMU_EVENT_SUF PE_KERNEL_PMU_EVENT PE_PMU_EVENT_FAKE
> %type <str> PE_DRV_CFG_TERM
> %destructor { free ($$); } <str>
> %type <term> event_term
> @@ -356,6 +356,39 @@ PE_PMU_EVENT_PRE '-' PE_PMU_EVENT_SUF sep_dc
> YYABORT;
> $$ = list;
> }
> +|
> +PE_PMU_EVENT_FAKE sep_dc
> +{
> + struct list_head *list;
> + int err;
> +
> + list = alloc_list();
> + if (!list)
> + YYABORT;
> +
> + err = parse_events_add_pmu(_parse_state, list, $1, NULL, false, false);
> + free($1);
> + if (err < 0)

nit: on error this needs:
free(list);
otherwise something like fuzz testing could go down the error path and
complain about memory leaks.

Thanks,
Ian

> + YYABORT;
> + $$ = list;
> +}
> +|
> +PE_PMU_EVENT_FAKE opt_pmu_config
> +{
> + struct list_head *list;
> + int err;
> +
> + list = alloc_list();
> + if (!list)
> + YYABORT;
> +
> + err = parse_events_add_pmu(_parse_state, list, $1, $2, false, false);
> + free($1);
> + parse_events_terms__delete($2);
> + if (err < 0)
> + YYABORT;
> + $$ = list;
> +}
>
> value_sym:
> PE_VALUE_SYM_HW
> --
> 2.25.4
>