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

Liang, Kan
2024-04-18T20:32:28Z

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.

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;
> }
> |