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Commit 100719dc authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt (VMware)
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tracing: Add simple expression support to hist triggers 

Add support for simple addition, subtraction, and unary expressions
(-(expr) and expr, where expr = b-a, a+b, a+b+c) to hist triggers, in
order to support a minimal set of useful inter-event calculations.

These operations are needed for calculating latencies between events
(timestamp1-timestamp0) and for combined latencies (latencies over 3
or more events).

In the process, factor out some common code from key and value
parsing.

Link: http://lkml.kernel.org/r/9a9308ead4fe32a433d9c7e95921fb798394f6b2.1516069914.git.tom.zanussi@linux.intel.com



Signed-off-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
[kbuild test robot fix, add static to parse_atom()]
Signed-off-by: default avatarFengguang Wu <fengguang.wu@intel.com>
[ Replaced '//' comments with normal /* */ comments ]
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 2ece94fb

kernel/trace/trace_events_hist.c

+413 −74
Original line number Diff line number Diff line
@@ -32,6 +32,13 @@ typedef u64 (*hist_field_fn_t) (struct hist_field *field, void *event, 
#define HIST_FIELD_OPERANDS_MAX	2

#define HIST_FIELDS_MAX		(TRACING_MAP_FIELDS_MAX + TRACING_MAP_VARS_MAX)



enum field_op_id {

	FIELD_OP_NONE,

	FIELD_OP_PLUS,

	FIELD_OP_MINUS,

	FIELD_OP_UNARY_MINUS,

};



struct hist_var {

	char				*name;

	struct hist_trigger_data	*hist_data;
@@ -48,6 +55,8 @@ struct hist_field { 
	struct hist_field		*operands[HIST_FIELD_OPERANDS_MAX];

	struct hist_trigger_data	*hist_data;

	struct hist_var			var;

	enum field_op_id		operator;

	char				*name;

};



static u64 hist_field_none(struct hist_field *field, void *event,
@@ -98,6 +107,41 @@ static u64 hist_field_log2(struct hist_field *hist_field, void *event, 
	return (u64) ilog2(roundup_pow_of_two(val));

}



static u64 hist_field_plus(struct hist_field *hist_field, void *event,

			   struct ring_buffer_event *rbe)

{

	struct hist_field *operand1 = hist_field->operands[0];

	struct hist_field *operand2 = hist_field->operands[1];



	u64 val1 = operand1->fn(operand1, event, rbe);

	u64 val2 = operand2->fn(operand2, event, rbe);



	return val1 + val2;

}



static u64 hist_field_minus(struct hist_field *hist_field, void *event,

			    struct ring_buffer_event *rbe)

{

	struct hist_field *operand1 = hist_field->operands[0];

	struct hist_field *operand2 = hist_field->operands[1];



	u64 val1 = operand1->fn(operand1, event, rbe);

	u64 val2 = operand2->fn(operand2, event, rbe);



	return val1 - val2;

}



static u64 hist_field_unary_minus(struct hist_field *hist_field, void *event,

				  struct ring_buffer_event *rbe)

{

	struct hist_field *operand = hist_field->operands[0];



	s64 sval = (s64)operand->fn(operand, event, rbe);

	u64 val = (u64)-sval;



	return val;

}



#define DEFINE_HIST_FIELD_FN(type)					\

	static u64 hist_field_##type(struct hist_field *hist_field,	\

				     void *event,			\
@@ -147,6 +191,7 @@ enum hist_field_flags { 
	HIST_FIELD_FL_TIMESTAMP		= 1 << 10,

	HIST_FIELD_FL_TIMESTAMP_USECS	= 1 << 11,

	HIST_FIELD_FL_VAR		= 1 << 12,

	HIST_FIELD_FL_EXPR		= 1 << 13,

};



struct var_defs {
@@ -258,6 +303,8 @@ 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_TIMESTAMP)

		field_name = "common_timestamp";

	else if (field->flags & HIST_FIELD_FL_EXPR)

		field_name = field->name;



	if (field_name == NULL)

		field_name = "";
@@ -519,12 +566,104 @@ static const char *get_hist_field_flags(struct hist_field *hist_field) 
	return flags_str;

}



static void expr_field_str(struct hist_field *field, char *expr)

{

	strcat(expr, hist_field_name(field, 0));



	if (field->flags) {

		const char *flags_str = get_hist_field_flags(field);



		if (flags_str) {

			strcat(expr, ".");

			strcat(expr, flags_str);

		}

	}

}



static char *expr_str(struct hist_field *field, unsigned int level)

{

	char *expr;



	if (level > 1)

		return NULL;



	expr = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL);

	if (!expr)

		return NULL;



	if (!field->operands[0]) {

		expr_field_str(field, expr);

		return expr;

	}



	if (field->operator == FIELD_OP_UNARY_MINUS) {

		char *subexpr;



		strcat(expr, "-(");

		subexpr = expr_str(field->operands[0], ++level);

		if (!subexpr) {

			kfree(expr);

			return NULL;

		}

		strcat(expr, subexpr);

		strcat(expr, ")");



		kfree(subexpr);



		return expr;

	}



	expr_field_str(field->operands[0], expr);



	switch (field->operator) {

	case FIELD_OP_MINUS:

		strcat(expr, "-");

		break;

	case FIELD_OP_PLUS:

		strcat(expr, "+");

		break;

	default:

		kfree(expr);

		return NULL;

	}



	expr_field_str(field->operands[1], expr);



	return expr;

}



static int contains_operator(char *str)

{

	enum field_op_id field_op = FIELD_OP_NONE;

	char *op;



	op = strpbrk(str, "+-");

	if (!op)

		return FIELD_OP_NONE;



	switch (*op) {

	case '-':

		if (*str == '-')

			field_op = FIELD_OP_UNARY_MINUS;

		else

			field_op = FIELD_OP_MINUS;

		break;

	case '+':

		field_op = FIELD_OP_PLUS;

		break;

	default:

		break;

	}



	return field_op;

}



static void destroy_hist_field(struct hist_field *hist_field,

			       unsigned int level)

{

	unsigned int i;



	if (level > 2)

	if (level > 3)

		return;



	if (!hist_field)
@@ -534,6 +673,7 @@ static void destroy_hist_field(struct hist_field *hist_field, 
		destroy_hist_field(hist_field->operands[i], level + 1);



	kfree(hist_field->var.name);

	kfree(hist_field->name);



	kfree(hist_field);

}
@@ -554,6 +694,9 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data, 


	hist_field->hist_data = hist_data;



	if (flags & HIST_FIELD_FL_EXPR)

		goto out; /* caller will populate */



	if (flags & HIST_FIELD_FL_HITCOUNT) {

		hist_field->fn = hist_field_counter;

		goto out;
@@ -626,6 +769,257 @@ static void destroy_hist_fields(struct hist_trigger_data *hist_data) 
	}

}



static struct ftrace_event_field *

parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file,

	    char *field_str, unsigned long *flags)

{

	struct ftrace_event_field *field = NULL;

	char *field_name, *modifier, *str;



	modifier = str = kstrdup(field_str, GFP_KERNEL);

	if (!modifier)

		return ERR_PTR(-ENOMEM);



	field_name = strsep(&modifier, ".");

	if (modifier) {

		if (strcmp(modifier, "hex") == 0)

			*flags |= HIST_FIELD_FL_HEX;

		else if (strcmp(modifier, "sym") == 0)

			*flags |= HIST_FIELD_FL_SYM;

		else if (strcmp(modifier, "sym-offset") == 0)

			*flags |= HIST_FIELD_FL_SYM_OFFSET;

		else if ((strcmp(modifier, "execname") == 0) &&

			 (strcmp(field_name, "common_pid") == 0))

			*flags |= HIST_FIELD_FL_EXECNAME;

		else if (strcmp(modifier, "syscall") == 0)

			*flags |= HIST_FIELD_FL_SYSCALL;

		else if (strcmp(modifier, "log2") == 0)

			*flags |= HIST_FIELD_FL_LOG2;

		else if (strcmp(modifier, "usecs") == 0)

			*flags |= HIST_FIELD_FL_TIMESTAMP_USECS;

		else {

			field = ERR_PTR(-EINVAL);

			goto out;

		}

	}



	if (strcmp(field_name, "common_timestamp") == 0) {

		*flags |= HIST_FIELD_FL_TIMESTAMP;

		hist_data->enable_timestamps = true;

		if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS)

			hist_data->attrs->ts_in_usecs = true;

	} else {

		field = trace_find_event_field(file->event_call, field_name);

		if (!field || !field->size) {

			field = ERR_PTR(-EINVAL);

			goto out;

		}

	}

 out:

	kfree(str);



	return field;

}



static struct hist_field *parse_atom(struct hist_trigger_data *hist_data,

				     struct trace_event_file *file, char *str,

				     unsigned long *flags, char *var_name)

{

	struct ftrace_event_field *field = NULL;

	struct hist_field *hist_field = NULL;

	int ret = 0;



	field = parse_field(hist_data, file, str, flags);

	if (IS_ERR(field)) {

		ret = PTR_ERR(field);

		goto out;

	}



	hist_field = create_hist_field(hist_data, field, *flags, var_name);

	if (!hist_field) {

		ret = -ENOMEM;

		goto out;

	}



	return hist_field;

 out:

	return ERR_PTR(ret);

}



static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,

				     struct trace_event_file *file,

				     char *str, unsigned long flags,

				     char *var_name, unsigned int level);



static struct hist_field *parse_unary(struct hist_trigger_data *hist_data,

				      struct trace_event_file *file,

				      char *str, unsigned long flags,

				      char *var_name, unsigned int level)

{

	struct hist_field *operand1, *expr = NULL;

	unsigned long operand_flags;

	int ret = 0;

	char *s;



	/* we support only -(xxx) i.e. explicit parens required */



	if (level > 3) {

		ret = -EINVAL;

		goto free;

	}



	str++; /* skip leading '-' */



	s = strchr(str, '(');

	if (s)

		str++;

	else {

		ret = -EINVAL;

		goto free;

	}



	s = strrchr(str, ')');

	if (s)

		*s = '\0';

	else {

		ret = -EINVAL; /* no closing ')' */

		goto free;

	}



	flags |= HIST_FIELD_FL_EXPR;

	expr = create_hist_field(hist_data, NULL, flags, var_name);

	if (!expr) {

		ret = -ENOMEM;

		goto free;

	}



	operand_flags = 0;

	operand1 = parse_expr(hist_data, file, str, operand_flags, NULL, ++level);

	if (IS_ERR(operand1)) {

		ret = PTR_ERR(operand1);

		goto free;

	}



	expr->flags |= operand1->flags &

		(HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);

	expr->fn = hist_field_unary_minus;

	expr->operands[0] = operand1;

	expr->operator = FIELD_OP_UNARY_MINUS;

	expr->name = expr_str(expr, 0);



	return expr;

 free:

	destroy_hist_field(expr, 0);

	return ERR_PTR(ret);

}



static int check_expr_operands(struct hist_field *operand1,

			       struct hist_field *operand2)

{

	unsigned long operand1_flags = operand1->flags;

	unsigned long operand2_flags = operand2->flags;



	if ((operand1_flags & HIST_FIELD_FL_TIMESTAMP_USECS) !=

	    (operand2_flags & HIST_FIELD_FL_TIMESTAMP_USECS))

		return -EINVAL;



	return 0;

}



static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,

				     struct trace_event_file *file,

				     char *str, unsigned long flags,

				     char *var_name, unsigned int level)

{

	struct hist_field *operand1 = NULL, *operand2 = NULL, *expr = NULL;

	unsigned long operand_flags;

	int field_op, ret = -EINVAL;

	char *sep, *operand1_str;



	if (level > 3)

		return ERR_PTR(-EINVAL);



	field_op = contains_operator(str);



	if (field_op == FIELD_OP_NONE)

		return parse_atom(hist_data, file, str, &flags, var_name);



	if (field_op == FIELD_OP_UNARY_MINUS)

		return parse_unary(hist_data, file, str, flags, var_name, ++level);



	switch (field_op) {

	case FIELD_OP_MINUS:

		sep = "-";

		break;

	case FIELD_OP_PLUS:

		sep = "+";

		break;

	default:

		goto free;

	}



	operand1_str = strsep(&str, sep);

	if (!operand1_str || !str)

		goto free;



	operand_flags = 0;

	operand1 = parse_atom(hist_data, file, operand1_str,

			      &operand_flags, NULL);

	if (IS_ERR(operand1)) {

		ret = PTR_ERR(operand1);

		operand1 = NULL;

		goto free;

	}



	/* rest of string could be another expression e.g. b+c in a+b+c */

	operand_flags = 0;

	operand2 = parse_expr(hist_data, file, str, operand_flags, NULL, ++level);

	if (IS_ERR(operand2)) {

		ret = PTR_ERR(operand2);

		operand2 = NULL;

		goto free;

	}



	ret = check_expr_operands(operand1, operand2);

	if (ret)

		goto free;



	flags |= HIST_FIELD_FL_EXPR;



	flags |= operand1->flags &

		(HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);



	expr = create_hist_field(hist_data, NULL, flags, var_name);

	if (!expr) {

		ret = -ENOMEM;

		goto free;

	}



	expr->operands[0] = operand1;

	expr->operands[1] = operand2;

	expr->operator = field_op;

	expr->name = expr_str(expr, 0);



	switch (field_op) {

	case FIELD_OP_MINUS:

		expr->fn = hist_field_minus;

		break;

	case FIELD_OP_PLUS:

		expr->fn = hist_field_plus;

		break;

	default:

		goto free;

	}



	return expr;

 free:

	destroy_hist_field(operand1, 0);

	destroy_hist_field(operand2, 0);

	destroy_hist_field(expr, 0);



	return ERR_PTR(ret);

}



static int create_hitcount_val(struct hist_trigger_data *hist_data)

{

	hist_data->fields[HITCOUNT_IDX] =
@@ -648,36 +1042,16 @@ static int __create_val_field(struct hist_trigger_data *hist_data, 
			      char *var_name, char *field_str,

			      unsigned long flags)

{

	struct ftrace_event_field *field = NULL;

	char *field_name;

	struct hist_field *hist_field;

	int ret = 0;



	field_name = strsep(&field_str, ".");

	if (field_str) {

		if (strcmp(field_str, "hex") == 0)

			flags |= HIST_FIELD_FL_HEX;

		else {

			ret = -EINVAL;

	hist_field = parse_expr(hist_data, file, field_str, flags, var_name, 0);

	if (IS_ERR(hist_field)) {

		ret = PTR_ERR(hist_field);

		goto out;

	}

	}



	if (strcmp(field_name, "common_timestamp") == 0) {

		flags |= HIST_FIELD_FL_TIMESTAMP;

		hist_data->enable_timestamps = true;

	} else {

		field = trace_find_event_field(file->event_call, field_name);

		if (!field || !field->size) {

			ret = -EINVAL;

			goto out;

		}

	}



	hist_data->fields[val_idx] = create_hist_field(hist_data, field, flags, var_name);

	if (!hist_data->fields[val_idx]) {

		ret = -ENOMEM;

		goto out;

	}

	hist_data->fields[val_idx] = hist_field;



	++hist_data->n_vals;

	++hist_data->n_fields;
@@ -765,8 +1139,8 @@ static int create_key_field(struct hist_trigger_data *hist_data, 
			    struct trace_event_file *file,

			    char *field_str)

{

	struct ftrace_event_field *field = NULL;

	struct hist_field *hist_field = NULL;



	unsigned long flags = 0;

	unsigned int key_size;

	int ret = 0;
@@ -781,60 +1155,24 @@ static int create_key_field(struct hist_trigger_data *hist_data, 
		key_size = sizeof(unsigned long) * HIST_STACKTRACE_DEPTH;

		hist_field = create_hist_field(hist_data, NULL, flags, NULL);

	} else {

		char *field_name = strsep(&field_str, ".");



		if (field_str) {

			if (strcmp(field_str, "hex") == 0)

				flags |= HIST_FIELD_FL_HEX;

			else if (strcmp(field_str, "sym") == 0)

				flags |= HIST_FIELD_FL_SYM;

			else if (strcmp(field_str, "sym-offset") == 0)

				flags |= HIST_FIELD_FL_SYM_OFFSET;

			else if ((strcmp(field_str, "execname") == 0) &&

				 (strcmp(field_name, "common_pid") == 0))

				flags |= HIST_FIELD_FL_EXECNAME;

			else if (strcmp(field_str, "syscall") == 0)

				flags |= HIST_FIELD_FL_SYSCALL;

			else if (strcmp(field_str, "log2") == 0)

				flags |= HIST_FIELD_FL_LOG2;

			else if (strcmp(field_str, "usecs") == 0)

				flags |= HIST_FIELD_FL_TIMESTAMP_USECS;

			else {

				ret = -EINVAL;

				goto out;

			}

		}



		if (strcmp(field_name, "common_timestamp") == 0) {

			flags |= HIST_FIELD_FL_TIMESTAMP;

			hist_data->enable_timestamps = true;

			if (flags & HIST_FIELD_FL_TIMESTAMP_USECS)

				hist_data->attrs->ts_in_usecs = true;

			key_size = sizeof(u64);

		} else {

			field = trace_find_event_field(file->event_call, field_name);

			if (!field || !field->size) {

				ret = -EINVAL;

		hist_field = parse_expr(hist_data, file, field_str, flags,

					NULL, 0);

		if (IS_ERR(hist_field)) {

			ret = PTR_ERR(hist_field);

			goto out;

		}



			if (is_string_field(field))

				key_size = MAX_FILTER_STR_VAL;

			else

				key_size = field->size;

		}

		key_size = hist_field->size;

	}



	hist_data->fields[key_idx] = create_hist_field(hist_data, field, flags, NULL);

	if (!hist_data->fields[key_idx]) {

		ret = -ENOMEM;

		goto out;

	}

	hist_data->fields[key_idx] = hist_field;



	key_size = ALIGN(key_size, sizeof(u64));

	hist_data->fields[key_idx]->size = key_size;

	hist_data->fields[key_idx]->offset = key_offset;



	hist_data->key_size += key_size;



	if (hist_data->key_size > HIST_KEY_SIZE_MAX) {

		ret = -EINVAL;

		goto out;
@@ -1419,7 +1757,8 @@ hist_trigger_entry_print(struct seq_file *m, 
	for (i = 1; i < hist_data->n_vals; i++) {

		field_name = hist_field_name(hist_data->fields[i], 0);



		if (hist_data->fields[i]->flags & HIST_FIELD_FL_VAR)

		if (hist_data->fields[i]->flags & HIST_FIELD_FL_VAR ||

		    hist_data->fields[i]->flags & HIST_FIELD_FL_EXPR)

			continue;



		if (hist_data->fields[i]->flags & HIST_FIELD_FL_HEX) {