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;
 }
 |
