[PATCH v2 13/16] perf parse-events: Improvements to modifier parsing

Ian Rogers
2024-04-16T07:30:49Z

Use a struct/bitmap rather than a copied string from lexer.

In lexer give improved error message when too many precise flags are
given or repeated modifiers.

Before:
```
$ perf stat -e 'cycles:kuk' true
event syntax error: 'cycles:kuk'
\___ Bad modifier
...
$ perf stat -e 'cycles:pppp' true
event syntax error: 'cycles:pppp'
\___ Bad modifier
...
$ perf stat -e '{instructions:p,cycles:pp}:pp' -a true
event syntax error: '..cycles:pp}:pp'
\___ Bad modifier
...
```
After:
```
$ perf stat -e 'cycles:kuk' true
event syntax error: 'cycles:kuk'
\___ Duplicate modifier 'k' (kernel)
...
$ perf stat -e 'cycles:pppp' true
event syntax error: 'cycles:pppp'
\___ Maximum precise value is 3
...
$ perf stat -e '{instructions:p,cycles:pp}:pp' true
event syntax error: '..cycles:pp}:pp'
\___ Maximum combined precise value is 3, adding precision to "cycles:pp"
...
```

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/parse-events.c | 250 ++++++++++++---------------------
tools/perf/util/parse-events.h | 23 ++-
tools/perf/util/parse-events.l | 75 +++++++++-
tools/perf/util/parse-events.y | 28 +---
4 files changed, 194 insertions(+), 182 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index ebada37ef98a..3ab533d0e653 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1700,12 +1700,6 @@ int parse_events_multi_pmu_add_or_add_pmu(struct parse_events_state *parse_state
return -EINVAL;
}

-int parse_events__modifier_group(struct list_head *list,
- char *event_mod)
-{
- return parse_events__modifier_event(list, event_mod, true);
-}
-
void parse_events__set_leader(char *name, struct list_head *list)
{
struct evsel *leader;
@@ -1720,183 +1714,125 @@ void parse_events__set_leader(char *name, struct list_head *list)
leader->group_name = name;
}

-struct event_modifier {
- int eu;
- int ek;
- int eh;
- int eH;
- int eG;
- int eI;
- int precise;
- int precise_max;
- int exclude_GH;
- int sample_read;
- int pinned;
- int weak;
- int exclusive;
- int bpf_counter;
-};
+static int parse_events__modifier_list(struct parse_events_state *parse_state,
+ YYLTYPE *loc,
+ struct list_head *list,
+ struct parse_events_modifier mod,
+ bool group)
+{
+ struct evsel *evsel;

-static int get_event_modifier(struct event_modifier *mod, char *str,
- struct evsel *evsel)
-{
- int eu = evsel ? evsel->core.attr.exclude_user : 0;
- int ek = evsel ? evsel->core.attr.exclude_kernel : 0;
- int eh = evsel ? evsel->core.attr.exclude_hv : 0;
- int eH = evsel ? evsel->core.attr.exclude_host : 0;
- int eG = evsel ? evsel->core.attr.exclude_guest : 0;
- int eI = evsel ? evsel->core.attr.exclude_idle : 0;
- int precise = evsel ? evsel->core.attr.precise_ip : 0;
- int precise_max = 0;
- int sample_read = 0;
- int pinned = evsel ? evsel->core.attr.pinned : 0;
- int exclusive = evsel ? evsel->core.attr.exclusive : 0;
-
- int exclude = eu | ek | eh;
- int exclude_GH = evsel ? evsel->exclude_GH : 0;
- int weak = 0;
- int bpf_counter = 0;
-
- memset(mod, 0, sizeof(*mod));
-
- while (*str) {
- if (*str == 'u') {
+ if (!group && mod.weak) {
+ parse_events_error__handle(parse_state->error, loc->first_column,
+ strdup("Weak modifier is for use with groups"), NULL);
+ return -EINVAL;
+ }
+
+ __evlist__for_each_entry(list, evsel) {
+ /* Translate modifiers into the equivalent evsel excludes. */
+ int eu = group ? evsel->core.attr.exclude_user : 0;
+ int ek = group ? evsel->core.attr.exclude_kernel : 0;
+ int eh = group ? evsel->core.attr.exclude_hv : 0;
+ int eH = group ? evsel->core.attr.exclude_host : 0;
+ int eG = group ? evsel->core.attr.exclude_guest : 0;
+ int exclude = eu | ek | eh;
+ int exclude_GH = group ? evsel->exclude_GH : 0;
+
+ if (mod.precise) {
+ /* use of precise requires exclude_guest */
+ eG = 1;
+ }
+ if (mod.user) {
if (!exclude)
exclude = eu = ek = eh = 1;
if (!exclude_GH && !perf_guest)
eG = 1;
eu = 0;
- } else if (*str == 'k') {
+ }
+ if (mod.kernel) {
if (!exclude)
exclude = eu = ek = eh = 1;
ek = 0;
- } else if (*str == 'h') {
+ }
+ if (mod.hypervisor) {
if (!exclude)
exclude = eu = ek = eh = 1;
eh = 0;
- } else if (*str == 'G') {
+ }
+ if (mod.guest) {
if (!exclude_GH)
exclude_GH = eG = eH = 1;
eG = 0;
- } else if (*str == 'H') {
+ }
+ if (mod.host) {
if (!exclude_GH)
exclude_GH = eG = eH = 1;
eH = 0;
- } else if (*str == 'I') {
- eI = 1;
- } else if (*str == 'p') {
- precise++;
- /* use of precise requires exclude_guest */
- if (!exclude_GH)
- eG = 1;
- } else if (*str == 'P') {
- precise_max = 1;
- } else if (*str == 'S') {
- sample_read = 1;
- } else if (*str == 'D') {
- pinned = 1;
- } else if (*str == 'e') {
- exclusive = 1;
- } else if (*str == 'W') {
- weak = 1;
- } else if (*str == 'b') {
- bpf_counter = 1;
- } else
- break;
-
- ++str;
+ }
+ evsel->core.attr.exclude_user = eu;
+ evsel->core.attr.exclude_kernel = ek;
+ evsel->core.attr.exclude_hv = eh;
+ evsel->core.attr.exclude_host = eH;
+ evsel->core.attr.exclude_guest = eG;
+ evsel->exclude_GH = exclude_GH;
+
+ /* Simple modifiers copied to the evsel. */
+ if (mod.precise) {
+ u8 precise = evsel->core.attr.precise_ip + mod.precise;
+ /*
+ * precise ip:
+ *
+ * 0 - SAMPLE_IP can have arbitrary skid
+ * 1 - SAMPLE_IP must have constant skid
+ * 2 - SAMPLE_IP requested to have 0 skid
+ * 3 - SAMPLE_IP must have 0 skid
+ *
+ * See also PERF_RECORD_MISC_EXACT_IP
+ */
+ if (precise > 3) {
+ char *help;
+
+ if (asprintf(&help,
+ "Maximum combined precise value is 3, adding precision to \"%s\"",
+ evsel__name(evsel)) > 0) {
+ parse_events_error__handle(parse_state->error,
+ loc->first_column,
+ help, NULL);
+ }
+ return -EINVAL;
+ }
+ evsel->core.attr.precise_ip = precise;
+ }
+ if (mod.precise_max)
+ evsel->precise_max = 1;
+ if (mod.non_idle)
+ evsel->core.attr.exclude_idle = 1;
+ if (mod.sample_read)
+ evsel->sample_read = 1;
+ if (mod.pinned && evsel__is_group_leader(evsel))
+ evsel->core.attr.pinned = 1;
+ if (mod.exclusive && evsel__is_group_leader(evsel))
+ evsel->core.attr.exclusive = 1;
+ if (mod.weak)
+ evsel->weak_group = true;
+ if (mod.bpf)
+ evsel->bpf_counter = true;
}
-
- /*
- * precise ip:
- *
- * 0 - SAMPLE_IP can have arbitrary skid
- * 1 - SAMPLE_IP must have constant skid
- * 2 - SAMPLE_IP requested to have 0 skid
- * 3 - SAMPLE_IP must have 0 skid
- *
- * See also PERF_RECORD_MISC_EXACT_IP
- */
- if (precise > 3)
- return -EINVAL;
-
- mod->eu = eu;
- mod->ek = ek;
- mod->eh = eh;
- mod->eH = eH;
- mod->eG = eG;
- mod->eI = eI;
- mod->precise = precise;
- mod->precise_max = precise_max;
- mod->exclude_GH = exclude_GH;
- mod->sample_read = sample_read;
- mod->pinned = pinned;
- mod->weak = weak;
- mod->bpf_counter = bpf_counter;
- mod->exclusive = exclusive;
-
return 0;
}

-/*
- * Basic modifier sanity check to validate it contains only one
- * instance of any modifier (apart from 'p') present.
- */
-static int check_modifier(char *str)
+int parse_events__modifier_group(struct parse_events_state *parse_state, void *loc,
+ struct list_head *list,
+ struct parse_events_modifier mod)
{
- char *p = str;
-
- /* The sizeof includes 0 byte as well. */
- if (strlen(str) > (sizeof("ukhGHpppPSDIWeb") - 1))
- return -1;
-
- while (*p) {
- if (*p != 'p' && strchr(p + 1, *p))
- return -1;
- p++;
- }
-
- return 0;
+ return parse_events__modifier_list(parse_state, loc, list, mod, /*group=*/true);
}

-int parse_events__modifier_event(struct list_head *list, char *str, bool add)
+int parse_events__modifier_event(struct parse_events_state *parse_state, void *loc,
+ struct list_head *list,
+ struct parse_events_modifier mod)
{
- struct evsel *evsel;
- struct event_modifier mod;
-
- if (str == NULL)
- return 0;
-
- if (check_modifier(str))
- return -EINVAL;
-
- if (!add && get_event_modifier(&mod, str, NULL))
- return -EINVAL;
-
- __evlist__for_each_entry(list, evsel) {
- if (add && get_event_modifier(&mod, str, evsel))
- return -EINVAL;
-
- evsel->core.attr.exclude_user = mod.eu;
- evsel->core.attr.exclude_kernel = mod.ek;
- evsel->core.attr.exclude_hv = mod.eh;
- evsel->core.attr.precise_ip = mod.precise;
- evsel->core.attr.exclude_host = mod.eH;
- evsel->core.attr.exclude_guest = mod.eG;
- evsel->core.attr.exclude_idle = mod.eI;
- evsel->exclude_GH = mod.exclude_GH;
- evsel->sample_read = mod.sample_read;
- evsel->precise_max = mod.precise_max;
- evsel->weak_group = mod.weak;
- evsel->bpf_counter = mod.bpf_counter;
-
- if (evsel__is_group_leader(evsel)) {
- evsel->core.attr.pinned = mod.pinned;
- evsel->core.attr.exclusive = mod.exclusive;
- }
- }
-
- return 0;
+ return parse_events__modifier_list(parse_state, loc, list, mod, /*group=*/false);
}

int parse_events_name(struct list_head *list, const char *name)
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index 290ae6c72ec5..f104faef1a78 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -186,8 +186,27 @@ void parse_events_terms__init(struct parse_events_terms *terms);
void parse_events_terms__exit(struct parse_events_terms *terms);
int parse_events_terms(struct parse_events_terms *terms, const char *str, FILE *input);
int parse_events_terms__to_strbuf(const struct parse_events_terms *terms, struct strbuf *sb);
-int parse_events__modifier_event(struct list_head *list, char *str, bool add);
-int parse_events__modifier_group(struct list_head *list, char *event_mod);
+
+struct parse_events_modifier {
+ u8 precise; /* Number of repeated 'p' for precision. */
+ bool precise_max : 1; /* 'P' */
+ bool non_idle : 1; /* 'I' */
+ bool sample_read : 1; /* 'S' */
+ bool pinned : 1; /* 'D' */
+ bool exclusive : 1; /* 'e' */
+ bool weak : 1; /* 'W' */
+ bool bpf : 1; /* 'b' */
+ bool user : 1; /* 'u' */
+ bool kernel : 1; /* 'k' */
+ bool hypervisor : 1; /* 'h' */
+ bool guest : 1; /* 'G' */
+ bool host : 1; /* 'H' */
+};
+
+int parse_events__modifier_event(struct parse_events_state *parse_state, void *loc,
+ struct list_head *list, struct parse_events_modifier mod);
+int parse_events__modifier_group(struct parse_events_state *parse_state, void *loc,
+ struct list_head *list, struct parse_events_modifier mod);
int parse_events_name(struct list_head *list, const char *name);
int parse_events_add_tracepoint(struct list_head *list, int *idx,
const char *sys, const char *event,
diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
index 0cd68c9f0d4f..4aaf0c53d9b6 100644
--- a/tools/perf/util/parse-events.l
+++ b/tools/perf/util/parse-events.l
@@ -142,6 +142,77 @@ static int hw(yyscan_t scanner, int config)
return PE_TERM_HW;
}

+static void modifiers_error(struct parse_events_state *parse_state, yyscan_t scanner,
+ int pos, char mod_char, const char *mod_name)
+{
+ struct parse_events_error *error = parse_state->error;
+ char *help = NULL;
+
+ if (asprintf(&help, "Duplicate modifier '%c' (%s)", mod_char, mod_name) > 0)
+ parse_events_error__handle(error, get_column(scanner) + pos, help , NULL);
+}
+
+static int modifiers(struct parse_events_state *parse_state, yyscan_t scanner)
+{
+ YYSTYPE *yylval = parse_events_get_lval(scanner);
+ char *text = parse_events_get_text(scanner);
+ struct parse_events_modifier mod = { .precise = 0, };
+
+ for (size_t i = 0, n = strlen(text); i < n; i++) {
+#define CASE(c, field) \
+ case c: \
+ if (mod.field) { \
+ modifiers_error(parse_state, scanner, i, c, #field); \
+ return PE_ERROR; \
+ } \
+ mod.field = true; \
+ break
+
+ switch (text[i]) {
+ CASE('u', user);
+ CASE('k', kernel);
+ CASE('h', hypervisor);
+ CASE('I', non_idle);
+ CASE('G', guest);
+ CASE('H', host);
+ case 'p':
+ mod.precise++;
+ /*
+ * precise ip:
+ *
+ * 0 - SAMPLE_IP can have arbitrary skid
+ * 1 - SAMPLE_IP must have constant skid
+ * 2 - SAMPLE_IP requested to have 0 skid
+ * 3 - SAMPLE_IP must have 0 skid
+ *
+ * See also PERF_RECORD_MISC_EXACT_IP
+ */
+ if (mod.precise > 3) {
+ struct parse_events_error *error = parse_state->error;
+ char *help = strdup("Maximum precise value is 3");
+
+ if (help) {
+ parse_events_error__handle(error, get_column(scanner) + i,
+ help , NULL);
+ }
+ return PE_ERROR;
+ }
+ break;
+ CASE('P', precise_max);
+ CASE('S', sample_read);
+ CASE('D', pinned);
+ CASE('W', weak);
+ CASE('e', exclusive);
+ CASE('b', bpf);
+ default:
+ return PE_ERROR;
+ }
+#undef CASE
+ }
+ yylval->mod = mod;
+ return PE_MODIFIER_EVENT;
+}
+
#define YY_USER_ACTION \
do { \
yylloc->last_column = yylloc->first_column; \
@@ -174,7 +245,7 @@ drv_cfg_term [a-zA-Z0-9_\.]+(=[a-zA-Z0-9_*?\.:]+)?
* If you add a modifier you need to update check_modifier().
* Also, the letters in modifier_event must not be in modifier_bp.
*/
-modifier_event [ukhpPGHSDIWeb]+
+modifier_event [ukhpPGHSDIWeb]{1,15}
modifier_bp [rwx]{1,3}
lc_type (L1-dcache|l1-d|l1d|L1-data|L1-icache|l1-i|l1i|L1-instruction|LLC|L2|dTLB|d-tlb|Data-TLB|iTLB|i-tlb|Instruction-TLB|branch|branches|bpu|btb|bpc|node)
lc_op_result (load|loads|read|store|stores|write|prefetch|prefetches|speculative-read|speculative-load|refs|Reference|ops|access|misses|miss)
@@ -341,7 +412,7 @@ r{num_raw_hex} { return str(yyscanner, PE_RAW); }
{num_dec} { return value(_parse_state, yyscanner, 10); }
{num_hex} { return value(_parse_state, yyscanner, 16); }

-{modifier_event} { return str(yyscanner, PE_MODIFIER_EVENT); }
+{modifier_event} { return modifiers(_parse_state, yyscanner); }
{name} { return str(yyscanner, PE_NAME); }
{name_tag} { return str(yyscanner, PE_NAME); }
"/" { BEGIN(config); return '/'; }
diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 2c4817e126c1..79f254189be6 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -68,11 +68,11 @@ static void free_list_evsel(struct list_head* list_evsel)
%type <num> PE_VALUE
%type <num> PE_VALUE_SYM_SW
%type <num> PE_VALUE_SYM_TOOL
+%type <mod> PE_MODIFIER_EVENT
%type <term_type> PE_TERM
%type <str> PE_RAW
%type <str> PE_NAME
%type <str> PE_LEGACY_CACHE
-%type <str> PE_MODIFIER_EVENT
%type <str> PE_MODIFIER_BP
%type <str> PE_EVENT_NAME
%type <str> PE_DRV_CFG_TERM
@@ -110,6 +110,7 @@ static void free_list_evsel(struct list_head* list_evsel)
{
char *str;
u64 num;
+ struct parse_events_modifier mod;
enum parse_events__term_type term_type;
struct list_head *list_evsel;
struct parse_events_terms *list_terms;
@@ -175,20 +176,13 @@ event
group:
group_def ':' PE_MODIFIER_EVENT
{
+ /* Apply the modifier to the events in the group_def. */
struct list_head *list = $1;
int err;

- err = parse_events__modifier_group(list, $3);
- free($3);
- if (err) {
- struct parse_events_state *parse_state = _parse_state;
- struct parse_events_error *error = parse_state->error;
-
- parse_events_error__handle(error, @3.first_column,
- strdup("Bad modifier"), NULL);
- free_list_evsel(list);
+ err = parse_events__modifier_group(_parse_state, &@3, list, $3);
+ if (err)
YYABORT;
- }
$$ = list;
}
|
@@ -238,17 +232,9 @@ event_name PE_MODIFIER_EVENT
* (there could be more events added for multiple tracepoint
* definitions via '*?'.
*/
- err = parse_events__modifier_event(list, $2, false);
- free($2);
- if (err) {
- struct parse_events_state *parse_state = _parse_state;
- struct parse_events_error *error = parse_state->error;
-
- parse_events_error__handle(error, @2.first_column,
- strdup("Bad modifier"), NULL);
- free_list_evsel(list);
+ err = parse_events__modifier_event(_parse_state, &@2, list, $2);
+ if (err)
YYABORT;
- }
$$ = list;
}
|