1 files changed, 150 insertions, 29 deletions

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1260c23cfa5f..1d536219b624 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -114,6 +114,7 @@ enum hist_field_fn {
 	HIST_FIELD_FN_BUCKET,
 	HIST_FIELD_FN_TIMESTAMP,
 	HIST_FIELD_FN_CPU,
+	HIST_FIELD_FN_COMM,
 	HIST_FIELD_FN_STRING,
 	HIST_FIELD_FN_DYNSTRING,
 	HIST_FIELD_FN_RELDYNSTRING,
@@ -506,6 +507,7 @@ enum hist_field_flags {
 	HIST_FIELD_FL_CONST		= 1 << 18,
 	HIST_FIELD_FL_PERCENT		= 1 << 19,
 	HIST_FIELD_FL_GRAPH		= 1 << 20,
+	HIST_FIELD_FL_COMM		= 1 << 21,
 };
 
 struct var_defs {
@@ -885,6 +887,15 @@ static u64 hist_field_cpu(struct hist_field *hist_field,
 	return cpu;
 }
 
+static u64 hist_field_comm(struct hist_field *hist_field,
+			  struct tracing_map_elt *elt,
+			  struct trace_buffer *buffer,
+			  struct ring_buffer_event *rbe,
+			  void *event)
+{
+	return (u64)(unsigned long)current->comm;
+}
+
 /**
  * check_field_for_var_ref - Check if a VAR_REF field references a variable
  * @hist_field: The VAR_REF field to check
@@ -1338,6 +1349,8 @@ static const char *hist_field_name(struct hist_field *field,
 		field_name = hist_field_name(field->operands[0], ++level);
 	else if (field->flags & HIST_FIELD_FL_CPU)
 		field_name = "common_cpu";
+	else if (field->flags & HIST_FIELD_FL_COMM)
+		field_name = "common_comm";
 	else if (field->flags & HIST_FIELD_FL_EXPR ||
 		 field->flags & HIST_FIELD_FL_VAR_REF) {
 		if (field->system) {
@@ -2015,6 +2028,13 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
 		goto out;
 	}
 
+	if (flags & HIST_FIELD_FL_COMM) {
+		hist_field->fn_num = HIST_FIELD_FN_COMM;
+		hist_field->size = MAX_FILTER_STR_VAL;
+		hist_field->type = "char[]";
+		goto out;
+	}
+
 	if (WARN_ON_ONCE(!field))
 		goto out;
 
@@ -2359,9 +2379,11 @@ parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file,
 			hist_data->attrs->ts_in_usecs = true;
 	} else if (strcmp(field_name, "common_stacktrace") == 0) {
 		*flags |= HIST_FIELD_FL_STACKTRACE;
-	} else if (strcmp(field_name, "common_cpu") == 0)
+	} else if (strcmp(field_name, "common_cpu") == 0) {
 		*flags |= HIST_FIELD_FL_CPU;
-	else if (strcmp(field_name, "hitcount") == 0)
+	} else if (strcmp(field_name, "common_comm") == 0) {
+		*flags |= HIST_FIELD_FL_COMM | HIST_FIELD_FL_STRING;
+	} else if (strcmp(field_name, "hitcount") == 0)
 		*flags |= HIST_FIELD_FL_HITCOUNT;
 	else {
 		field = trace_find_event_field(file->event_call, field_name);
@@ -2377,6 +2399,8 @@ parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file,
 				*flags |= HIST_FIELD_FL_CPU;
 			} else if (field && field->filter_type == FILTER_STACKTRACE) {
 				*flags |= HIST_FIELD_FL_STACKTRACE;
+			} else if (field && field->filter_type == FILTER_COMM) {
+				*flags |= HIST_FIELD_FL_COMM | HIST_FIELD_FL_STRING;
 			} else {
 				hist_err(tr, HIST_ERR_FIELD_NOT_FOUND,
 					 errpos(field_name));
@@ -4327,6 +4351,8 @@ static u64 hist_fn_call(struct hist_field *hist_field,
 		return hist_field_timestamp(hist_field, elt, buffer, rbe, event);
 	case HIST_FIELD_FN_CPU:
 		return hist_field_cpu(hist_field, elt, buffer, rbe, event);
+	case HIST_FIELD_FN_COMM:
+		return hist_field_comm(hist_field, elt, buffer, rbe, event);
 	case HIST_FIELD_FN_STRING:
 		return hist_field_string(hist_field, elt, buffer, rbe, event);
 	case HIST_FIELD_FN_DYNSTRING:
@@ -5212,22 +5238,25 @@ static inline void add_to_key(char *compound_key, void *key,
 	size_t size = key_field->size;
 
 	if (key_field->flags & HIST_FIELD_FL_STRING) {
-		struct ftrace_event_field *field;
 
-		field = key_field->field;
-		if (field->filter_type == FILTER_DYN_STRING ||
-		    field->filter_type == FILTER_RDYN_STRING)
-			size = *(u32 *)(rec + field->offset) >> 16;
-		else if (field->filter_type == FILTER_STATIC_STRING)
-			size = field->size;
+		if (key_field->flags & HIST_FIELD_FL_COMM) {
+			size = strlen((char *)key);
+		} else {
+			struct ftrace_event_field *field;
+
+			field = key_field->field;
+			if (field->filter_type == FILTER_DYN_STRING ||
+			    field->filter_type == FILTER_RDYN_STRING)
+				size = *(u32 *)(rec + field->offset) >> 16;
+			else if (field->filter_type == FILTER_STATIC_STRING)
+				size = field->size;
+		}
 
 		/* ensure NULL-termination */
 		if (size > key_field->size - 1)
 			size = key_field->size - 1;
-
-		strncpy(compound_key + key_field->offset, (char *)key, size);
-	} else
-		memcpy(compound_key + key_field->offset, key, size);
+	}
+	memcpy(compound_key + key_field->offset, key, size);
 }
 
 static void
@@ -5246,17 +5275,94 @@ hist_trigger_actions(struct hist_trigger_data *hist_data,
 	}
 }
 
+/*
+ * The hist_pad structure is used to save information to create
+ * a histogram from the histogram trigger. It's too big to store
+ * on the stack, so when the histogram trigger is initialized
+ * a percpu array of 4 hist_pad structures is allocated.
+ * This will cover every context from normal, softirq, irq and NMI
+ * in the very unlikely event that a tigger happens at each of
+ * these contexts and interrupts a currently active trigger.
+ */
+struct hist_pad {
+	unsigned long		entries[HIST_STACKTRACE_DEPTH];
+	u64			var_ref_vals[TRACING_MAP_VARS_MAX];
+	char			compound_key[HIST_KEY_SIZE_MAX];
+};
+
+static struct hist_pad __percpu *hist_pads;
+static DEFINE_PER_CPU(int, hist_pad_cnt);
+static refcount_t hist_pad_ref;
+
+/* One hist_pad for every context (normal, softirq, irq, NMI) */
+#define MAX_HIST_CNT 4
+
+static int alloc_hist_pad(void)
+{
+	lockdep_assert_held(&event_mutex);
+
+	if (refcount_read(&hist_pad_ref)) {
+		refcount_inc(&hist_pad_ref);
+		return 0;
+	}
+
+	hist_pads = __alloc_percpu(sizeof(struct hist_pad) * MAX_HIST_CNT,
+				   __alignof__(struct hist_pad));
+	if (!hist_pads)
+		return -ENOMEM;
+
+	refcount_set(&hist_pad_ref, 1);
+	return 0;
+}
+
+static void free_hist_pad(void)
+{
+	lockdep_assert_held(&event_mutex);
+
+	if (!refcount_dec_and_test(&hist_pad_ref))
+		return;
+
+	free_percpu(hist_pads);
+	hist_pads = NULL;
+}
+
+static struct hist_pad *get_hist_pad(void)
+{
+	struct hist_pad *hist_pad;
+	int cnt;
+
+	if (WARN_ON_ONCE(!hist_pads))
+		return NULL;
+
+	preempt_disable();
+
+	hist_pad = per_cpu_ptr(hist_pads, smp_processor_id());
+
+	if (this_cpu_read(hist_pad_cnt) == MAX_HIST_CNT) {
+		preempt_enable();
+		return NULL;
+	}
+
+	cnt = this_cpu_inc_return(hist_pad_cnt) - 1;
+
+	return &hist_pad[cnt];
+}
+
+static void put_hist_pad(void)
+{
+	this_cpu_dec(hist_pad_cnt);
+	preempt_enable();
+}
+
 static void event_hist_trigger(struct event_trigger_data *data,
 			       struct trace_buffer *buffer, void *rec,
 			       struct ring_buffer_event *rbe)
 {
 	struct hist_trigger_data *hist_data = data->private_data;
 	bool use_compound_key = (hist_data->n_keys > 1);
-	unsigned long entries[HIST_STACKTRACE_DEPTH];
-	u64 var_ref_vals[TRACING_MAP_VARS_MAX];
-	char compound_key[HIST_KEY_SIZE_MAX];
 	struct tracing_map_elt *elt = NULL;
 	struct hist_field *key_field;
+	struct hist_pad *hist_pad;
 	u64 field_contents;
 	void *key = NULL;
 	unsigned int i;
@@ -5264,12 +5370,18 @@ static void event_hist_trigger(struct event_trigger_data *data,
 	if (unlikely(!rbe))
 		return;
 
-	memset(compound_key, 0, hist_data->key_size);
+	hist_pad = get_hist_pad();
+	if (!hist_pad)
+		return;
+
+	memset(hist_pad->compound_key, 0, hist_data->key_size);
 
 	for_each_hist_key_field(i, hist_data) {
 		key_field = hist_data->fields[i];
 
 		if (key_field->flags & HIST_FIELD_FL_STACKTRACE) {
+			unsigned long *entries = hist_pad->entries;
+
 			memset(entries, 0, HIST_STACKTRACE_SIZE);
 			if (key_field->field) {
 				unsigned long *stack, n_entries;
@@ -5293,26 +5405,31 @@ static void event_hist_trigger(struct event_trigger_data *data,
 		}
 
 		if (use_compound_key)
-			add_to_key(compound_key, key, key_field, rec);
+			add_to_key(hist_pad->compound_key, key, key_field, rec);
 	}
 
 	if (use_compound_key)
-		key = compound_key;
+		key = hist_pad->compound_key;
 
 	if (hist_data->n_var_refs &&
-	    !resolve_var_refs(hist_data, key, var_ref_vals, false))
-		return;
+	    !resolve_var_refs(hist_data, key, hist_pad->var_ref_vals, false))
+		goto out;
 
 	elt = tracing_map_insert(hist_data->map, key);
 	if (!elt)
-		return;
+		goto out;
 
-	hist_trigger_elt_update(hist_data, elt, buffer, rec, rbe, var_ref_vals);
+	hist_trigger_elt_update(hist_data, elt, buffer, rec, rbe, hist_pad->var_ref_vals);
 
-	if (resolve_var_refs(hist_data, key, var_ref_vals, true))
-		hist_trigger_actions(hist_data, elt, buffer, rec, rbe, key, var_ref_vals);
+	if (resolve_var_refs(hist_data, key, hist_pad->var_ref_vals, true)) {
+		hist_trigger_actions(hist_data, elt, buffer, rec, rbe,
+				     key, hist_pad->var_ref_vals);
+	}
 
 	hist_poll_wakeup();
+
+ out:
+	put_hist_pad();
 }
 
 static void hist_trigger_stacktrace_print(struct seq_file *m,
@@ -6011,6 +6128,8 @@ static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
 
 	if (hist_field->flags & HIST_FIELD_FL_CPU)
 		seq_puts(m, "common_cpu");
+	if (hist_field->flags & HIST_FIELD_FL_COMM)
+		seq_puts(m, "common_comm");
 	else if (hist_field->flags & HIST_FIELD_FL_CONST)
 		seq_printf(m, "%llu", hist_field->constant);
 	else if (field_name) {
@@ -6157,6 +6276,9 @@ static int event_hist_trigger_init(struct event_trigger_data *data)
 {
 	struct hist_trigger_data *hist_data = data->private_data;
 
+	if (alloc_hist_pad() < 0)
+		return -ENOMEM;
+
 	if (!data->ref && hist_data->attrs->name)
 		save_named_trigger(hist_data->attrs->name, data);
 
@@ -6201,6 +6323,7 @@ static void event_hist_trigger_free(struct event_trigger_data *data)
 
 		destroy_hist_data(hist_data);
 	}
+	free_hist_pad();
 }
 
 static const struct event_trigger_ops event_hist_trigger_ops = {
@@ -6216,9 +6339,7 @@ static int event_hist_trigger_named_init(struct event_trigger_data *data)
 
 	save_named_trigger(data->named_data->name, data);
 
-	event_hist_trigger_init(data->named_data);
-
-	return 0;
+	return event_hist_trigger_init(data->named_data);
 }
 
 static void event_hist_trigger_named_free(struct event_trigger_data *data)
@@ -6705,7 +6826,7 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
 		return PTR_ERR(hist_data);
 	}
 
-	trigger_data = event_trigger_alloc(cmd_ops, cmd, param, hist_data);
+	trigger_data = trigger_data_alloc(cmd_ops, cmd, param, hist_data);
 	if (!trigger_data) {
 		ret = -ENOMEM;
 		goto out_free;