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

Ian Rogers
2024-04-19T06:22:44Z

On Thu, Apr 18, 2024 at 1:32 PM Liang, Kan <kan.liang@linux.intel.com> wrote:
>
>
>
> On 2024-04-16 2:15 a.m., Ian Rogers wrote:
> > 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) {
>
> The pmu_max_precise() should return the max precise the current kernel
> supports. It checks the /sys/devices/cpu/caps/max_precise.
>
> I think we should use that value rather than hard code it to 3.

I'll add an extra patch to do that. I'm a bit concerned it may break
event parsing on platforms not supporting max_precise of 3.

Thanks,
Ian

> Thanks,
> Kan
>
> > + 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;
> > }
> > |