Re: [PATCH 15/19] perf metric: Add recursion check when processing nested metrics

Arnaldo Carvalho de Melo
2020-07-28T12:35:18Z

Em Sun, Jul 19, 2020 at 03:40:26PM -0700, Ian Rogers escreveu:
> On Sun, Jul 19, 2020 at 11:14 AM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > Keeping the stack of nested metrics via 'struct expr_id' objects
> > and checking if we are in recursion via already processed metric.
> >
> > The stack is implemented as static array within the struct egroup
> > with 100 entries, which should be enough nesting depth for any
> > metric we have or plan to have at the moment.
> >
> > Adding test that simulates the recursion and checks we can
> > detect it.
> >
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
>
> Acked-by: Ian Rogers <irogers@google.com>

Thanks, applied.

- Arnaldo

> Thanks,
> Ian
>
> > ---
> > tools/perf/tests/parse-metric.c | 34 +++++++++-
> > tools/perf/util/expr.c | 2 +
> > tools/perf/util/expr.h | 9 ++-
> > tools/perf/util/metricgroup.c | 117 +++++++++++++++++++++++++++++---
> > 4 files changed, 149 insertions(+), 13 deletions(-)
> >
> > diff --git a/tools/perf/tests/parse-metric.c b/tools/perf/tests/parse-metric.c
> > index aa4d5a9f09a8..01370ccb9ed9 100644
> > --- a/tools/perf/tests/parse-metric.c
> > +++ b/tools/perf/tests/parse-metric.c
> > @@ -57,6 +57,18 @@ static struct pmu_event pme_test[] = {
> > .metric_expr = "d_ratio(dcache_l2_all_miss, dcache_l2_all)",
> > .metric_name = "DCache_L2_Misses",
> > },
> > +{
> > + .metric_expr = "ipc + m2",
> > + .metric_name = "M1",
> > +},
> > +{
> > + .metric_expr = "ipc + m1",
> > + .metric_name = "M2",
> > +},
> > +{
> > + .metric_expr = "1/m3",
> > + .metric_name = "M3",
> > +}
> > };
> >
> > static struct pmu_events_map map = {
> > @@ -139,8 +151,8 @@ static int compute_metric(const char *name, struct value *vals, double *ratio)
> > err = metricgroup__parse_groups_test(evlist, &map, name,
> > false, false,
> > &metric_events);
> > -
> > - TEST_ASSERT_VAL("failed to parse metric", err == 0);
> > + if (err)
> > + return err;
> >
> > if (perf_evlist__alloc_stats(evlist, false))
> > return -1;
> > @@ -264,11 +276,29 @@ static int test_dcache_l2(void)
> > return 0;
> > }
> >
> > +static int test_recursion_fail(void)
> > +{
> > + double ratio;
> > + struct value vals[] = {
> > + { .event = "inst_retired.any", .val = 300 },
> > + { .event = "cpu_clk_unhalted.thread", .val = 200 },
> > + { 0 },
> > + };
> > +
> > + TEST_ASSERT_VAL("failed to find recursion",
> > + compute_metric("M1", vals, &ratio) == -1);
> > +
> > + TEST_ASSERT_VAL("failed to find recursion",
> > + compute_metric("M3", vals, &ratio) == -1);
> > + return 0;
> > +}
> > +
> > int test__parse_metric(struct test *test __maybe_unused, int subtest __maybe_unused)
> > {
> > TEST_ASSERT_VAL("IPC failed", test_ipc() == 0);
> > TEST_ASSERT_VAL("frontend failed", test_frontend() == 0);
> > TEST_ASSERT_VAL("cache_miss_cycles failed", test_cache_miss_cycles() == 0);
> > TEST_ASSERT_VAL("DCache_L2 failed", test_dcache_l2() == 0);
> > + TEST_ASSERT_VAL("recursion fail failed", test_recursion_fail() == 0);
> > return 0;
> > }
> > diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
> > index a346ca590513..53482ef53c41 100644
> > --- a/tools/perf/util/expr.c
> > +++ b/tools/perf/util/expr.c
> > @@ -47,6 +47,8 @@ int expr__add_id(struct expr_parse_ctx *ctx, const char *id)
> > if (!data_ptr)
> > return -ENOMEM;
> >
> > + data_ptr->parent = ctx->parent;
> > +
> > ret = hashmap__set(&ctx->ids, id, data_ptr,
> > (const void **)&old_key, (void **)&old_data);
> > if (ret)
> > diff --git a/tools/perf/util/expr.h b/tools/perf/util/expr.h
> > index 9ed208d93418..fc2b5e824a66 100644
> > --- a/tools/perf/util/expr.h
> > +++ b/tools/perf/util/expr.h
> > @@ -13,8 +13,14 @@
> >
> > struct metric_ref;
> >
> > +struct expr_id {
> > + char *id;
> > + struct expr_id *parent;
> > +};
> > +
> > struct expr_parse_ctx {
> > - struct hashmap ids;
> > + struct hashmap ids;
> > + struct expr_id *parent;
> > };
> >
> > struct expr_id_data {
> > @@ -25,6 +31,7 @@ struct expr_id_data {
> > const char *metric_expr;
> > bool counted;
> > } ref;
> > + struct expr_id *parent;
> > };
> >
> > bool is_ref;
> > diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> > index 332414d93f7a..2a45ee94fd61 100644
> > --- a/tools/perf/util/metricgroup.c
> > +++ b/tools/perf/util/metricgroup.c
> > @@ -24,6 +24,7 @@
> > #include <subcmd/parse-options.h>
> > #include <api/fs/fs.h>
> > #include "util.h"
> > +#include <asm/bug.h>
> >
> > struct metric_event *metricgroup__lookup(struct rblist *metric_events,
> > struct evsel *evsel,
> > @@ -126,6 +127,28 @@ struct egroup {
> > bool has_constraint;
> > };
> >
> > +#define RECURSION_ID_MAX 100
> > +
> > +struct expr_ids {
> > + struct expr_id id[RECURSION_ID_MAX];
> > + int cnt;
> > +};
> > +
> > +static struct expr_id *expr_ids__alloc(struct expr_ids *ids)
> > +{
> > + if (ids->cnt >= RECURSION_ID_MAX)
> > + return NULL;
> > + return &ids->id[ids->cnt++];
> > +}
> > +
> > +static void expr_ids__exit(struct expr_ids *ids)
> > +{
> > + int i;
> > +
> > + for (i = 0; i < ids->cnt; i++)
> > + free(ids->id[i].id);
> > +}
> > +
> > /**
> > * Find a group of events in perf_evlist that correpond to those from a parsed
> > * metric expression. Note, as find_evsel_group is called in the same order as
> > @@ -620,7 +643,9 @@ static int __add_metric(struct list_head *group_list,
> > struct pmu_event *pe,
> > bool metric_no_group,
> > int runtime,
> > - struct egroup **egp)
> > + struct egroup **egp,
> > + struct expr_id *parent,
> > + struct expr_ids *ids)
> > {
> > struct metric_ref_node *ref;
> > struct egroup *eg;
> > @@ -630,7 +655,7 @@ static int __add_metric(struct list_head *group_list,
> > * We got in here for the parent group,
> > * allocate it and put it on the list.
> > */
> > - eg = malloc(sizeof(*eg));
> > + eg = zalloc(sizeof(*eg));
> > if (!eg)
> > return -ENOMEM;
> >
> > @@ -643,6 +668,18 @@ static int __add_metric(struct list_head *group_list,
> > INIT_LIST_HEAD(&eg->metric_refs);
> > eg->metric_refs_cnt = 0;
> > *egp = eg;
> > +
> > + parent = expr_ids__alloc(ids);
> > + if (!parent) {
> > + free(eg);
> > + return -EINVAL;
> > + }
> > +
> > + parent->id = strdup(pe->metric_name);
> > + if (!parent->id) {
> > + free(eg);
> > + return -ENOMEM;
> > + }
> > } else {
> > /*
> > * We got here for the referenced metric, via the
> > @@ -668,6 +705,10 @@ static int __add_metric(struct list_head *group_list,
> > eg->metric_refs_cnt++;
> > }
> >
> > + /* Force all found IDs in metric to have us as parent ID. */
> > + WARN_ON_ONCE(!parent);
> > + eg->pctx.parent = parent;
> > +
> > /*
> > * For both the parent and referenced metrics, we parse
> > * all the metric's IDs and add it to the parent context.
> > @@ -728,15 +769,62 @@ static struct pmu_event *find_metric(const char *metric, struct pmu_events_map *
> > return NULL;
> > }
> >
> > +static int recursion_check(struct egroup *eg, const char *id, struct expr_id **parent,
> > + struct expr_ids *ids)
> > +{
> > + struct expr_id_data *data;
> > + struct expr_id *p;
> > + int ret;
> > +
> > + /*
> > + * We get the parent referenced by 'id' argument and
> > + * traverse through all the parent object IDs to check
> > + * if we already processed 'id', if we did, it's recursion
> > + * and we fail.
> > + */
> > + ret = expr__get_id(&eg->pctx, id, &data);
> > + if (ret)
> > + return ret;
> > +
> > + p = data->parent;
> > +
> > + while (p->parent) {
> > + if (!strcmp(p->id, id)) {
> > + pr_err("failed: recursion detected for %s\n", id);
> > + return -1;
> > + }
> > + p = p->parent;
> > + }
> > +
> > + /*
> > + * If we are over the limit of static entris, the metric
> > + * is too difficult/nested to process, fail as well.
> > + */
> > + p = expr_ids__alloc(ids);
> > + if (!p) {
> > + pr_err("failed: too many nested metrics\n");
> > + return -EINVAL;
> > + }
> > +
> > + p->id = strdup(id);
> > + p->parent = data->parent;
> > + *parent = p;
> > +
> > + return p->id ? 0 : -ENOMEM;
> > +}
> > +
> > static int add_metric(struct list_head *group_list,
> > struct pmu_event *pe,
> > bool metric_no_group,
> > - struct egroup **egp);
> > + struct egroup **egp,
> > + struct expr_id *parent,
> > + struct expr_ids *ids);
> >
> > static int resolve_metric(struct egroup *eg,
> > bool metric_no_group,
> > struct list_head *group_list,
> > - struct pmu_events_map *map)
> > + struct pmu_events_map *map,
> > + struct expr_ids *ids)
> > {
> > struct hashmap_entry *cur;
> > size_t bkt;
> > @@ -750,18 +838,23 @@ static int resolve_metric(struct egroup *eg,
> > do {
> > all = true;
> > hashmap__for_each_entry((&eg->pctx.ids), cur, bkt) {
> > + struct expr_id *parent;
> > struct pmu_event *pe;
> >
> > pe = find_metric(cur->key, map);
> > if (!pe)
> > continue;
> >
> > + ret = recursion_check(eg, cur->key, &parent, ids);
> > + if (ret)
> > + return ret;
> > +
> > all = false;
> > /* The metric key itself needs to go out.. */
> > expr__del_id(&eg->pctx, cur->key);
> >
> > /* ... and it gets resolved to the parent context. */
> > - ret = add_metric(group_list, pe, metric_no_group, &eg);
> > + ret = add_metric(group_list, pe, metric_no_group, &eg, parent, ids);
> > if (ret)
> > return ret;
> >
> > @@ -779,14 +872,16 @@ static int resolve_metric(struct egroup *eg,
> > static int add_metric(struct list_head *group_list,
> > struct pmu_event *pe,
> > bool metric_no_group,
> > - struct egroup **egp)
> > + struct egroup **egp,
> > + struct expr_id *parent,
> > + struct expr_ids *ids)
> > {
> > int ret = 0;
> >
> > pr_debug("metric expr %s for %s\n", pe->metric_expr, pe->metric_name);
> >
> > if (!strstr(pe->metric_expr, "?")) {
> > - ret = __add_metric(group_list, pe, metric_no_group, 1, egp);
> > + ret = __add_metric(group_list, pe, metric_no_group, 1, egp, parent, ids);
> > } else {
> > int j, count;
> >
> > @@ -798,7 +893,7 @@ static int add_metric(struct list_head *group_list,
> > */
> >
> > for (j = 0; j < count && !ret; j++) {
> > - ret = __add_metric(group_list, pe, metric_no_group, j, egp);
> > + ret = __add_metric(group_list, pe, metric_no_group, j, egp, parent, ids);
> > }
> > }
> >
> > @@ -811,6 +906,7 @@ static int metricgroup__add_metric(const char *metric, bool metric_no_group,
> > struct pmu_events_map *map)
> >
> > {
> > + struct expr_ids ids = { 0 };
> > struct pmu_event *pe;
> > struct egroup *eg;
> > LIST_HEAD(list);
> > @@ -821,7 +917,7 @@ static int metricgroup__add_metric(const char *metric, bool metric_no_group,
> > has_match = true;
> > eg = NULL;
> >
> > - ret = add_metric(&list, pe, metric_no_group, &eg);
> > + ret = add_metric(&list, pe, metric_no_group, &eg, NULL, &ids);
> > if (ret)
> > return ret;
> >
> > @@ -830,7 +926,7 @@ static int metricgroup__add_metric(const char *metric, bool metric_no_group,
> > * included in the expression.
> > */
> > ret = resolve_metric(eg, metric_no_group,
> > - &list, map);
> > + &list, map, &ids);
> > if (ret)
> > return ret;
> > }
> > @@ -853,6 +949,7 @@ static int metricgroup__add_metric(const char *metric, bool metric_no_group,
> > }
> >
> > list_splice(&list, group_list);
> > + expr_ids__exit(&ids);
> > return 0;
> > }
> >
> > --
> > 2.25.4
> >

--

- Arnaldo