kernel/trace/trace_events_filter.c - linux - Git at Google

 /*
  * trace_events_filter - generic event filtering
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  *
  * Copyright (C) 2009 Tom Zanussi <tzanussi@gmail.com>
  */

 #include <linux/debugfs.h>
 #include <linux/uaccess.h>
 #include <linux/module.h>
 #include <linux/ctype.h>

 #include "trace.h"
 #include "trace_output.h"

 static int filter_pred_64(struct filter_pred *pred, void *event)
 {
 	u64 *addr = (u64 *)(event + pred->offset);
 	u64 val = (u64)pred->val;
 	int match;

 	match = (val == *addr) ^ pred->not;

 	return match;
 }

 static int filter_pred_32(struct filter_pred *pred, void *event)
 {
 	u32 *addr = (u32 *)(event + pred->offset);
 	u32 val = (u32)pred->val;
 	int match;

 	match = (val == *addr) ^ pred->not;

 	return match;
 }

 static int filter_pred_16(struct filter_pred *pred, void *event)
 {
 	u16 *addr = (u16 *)(event + pred->offset);
 	u16 val = (u16)pred->val;
 	int match;

 	match = (val == *addr) ^ pred->not;

 	return match;
 }

 static int filter_pred_8(struct filter_pred *pred, void *event)
 {
 	u8 *addr = (u8 *)(event + pred->offset);
 	u8 val = (u8)pred->val;
 	int match;

 	match = (val == *addr) ^ pred->not;

 	return match;
 }

 static int filter_pred_string(struct filter_pred *pred, void *event)
 {
 	char *addr = (char *)(event + pred->offset);
 	int cmp, match;

 	cmp = strncmp(addr, pred->str_val, pred->str_len);

 	match = (!cmp) ^ pred->not;

 	return match;
 }

 /* return 1 if event matches, 0 otherwise (discard) */
 int filter_match_preds(struct ftrace_event_call *call, void *rec)
 {
 	int i, matched, and_failed = 0;
 	struct filter_pred *pred;

 	for (i = 0; i < MAX_FILTER_PRED; i++) {
 		if (call->preds[i]) {
 			pred = call->preds[i];
 			if (and_failed && !pred->or)
 				continue;
 			matched = pred->fn(pred, rec);
 			if (!matched && !pred->or) {
 				and_failed = 1;
 				continue;
 			} else if (matched && pred->or)
 				return 1;
 		} else
 			break;
 	}

 	if (and_failed)
 		return 0;

 	return 1;
 }

 void filter_print_preds(struct filter_pred **preds, struct trace_seq *s)
 {
 	char *field_name;
 	struct filter_pred *pred;
 	int i;

 	if (!preds) {
 		trace_seq_printf(s, "none\n");
 		return;
 	}

 	for (i = 0; i < MAX_FILTER_PRED; i++) {
 		if (preds[i]) {
 			pred = preds[i];
 			field_name = pred->field_name;
 			if (i)
 				trace_seq_printf(s, pred->or ? "|| " : "&& ");
 			trace_seq_printf(s, "%s ", field_name);
 			trace_seq_printf(s, pred->not ? "!= " : "== ");
 			if (pred->str_val)
 				trace_seq_printf(s, "%s\n", pred->str_val);
 			else
 				trace_seq_printf(s, "%llu\n", pred->val);
 		} else
 			break;
 	}
 }

 static struct ftrace_event_field *
 find_event_field(struct ftrace_event_call *call, char *name)
 {
 	struct ftrace_event_field *field;

 	list_for_each_entry(field, &call->fields, link) {
 		if (!strcmp(field->name, name))
 			return field;
 	}

 	return NULL;
 }

 void filter_free_pred(struct filter_pred *pred)
 {
 	if (!pred)
 		return;

 	kfree(pred->field_name);
 	kfree(pred->str_val);
 	kfree(pred);
 }

 void filter_free_preds(struct ftrace_event_call *call)
 {
 	int i;

 	if (call->preds) {
 		for (i = 0; i < MAX_FILTER_PRED; i++)
 			filter_free_pred(call->preds[i]);
 		kfree(call->preds);
 		call->preds = NULL;
 	}
 }

 void filter_free_subsystem_preds(struct event_subsystem *system)
 {
 	struct ftrace_event_call *call = __start_ftrace_events;
 	int i;

 	if (system->preds) {
 		for (i = 0; i < MAX_FILTER_PRED; i++)
 			filter_free_pred(system->preds[i]);
 		kfree(system->preds);
 		system->preds = NULL;
 	}

 	events_for_each(call) {
 		if (!call->name || !call->regfunc)
 			continue;

 		if (!strcmp(call->system, system->name))
 			filter_free_preds(call);
 	}
 }

 static int __filter_add_pred(struct ftrace_event_call *call,
 			     struct filter_pred *pred)
 {
 	int i;

 	if (call->preds && !pred->compound)
 		filter_free_preds(call);

 	if (!call->preds) {
 		call->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
 				      GFP_KERNEL);
 		if (!call->preds)
 			return -ENOMEM;
 	}

 	for (i = 0; i < MAX_FILTER_PRED; i++) {
 		if (!call->preds[i]) {
 			call->preds[i] = pred;
 			return 0;
 		}
 	}

 	return -ENOSPC;
 }

 static int is_string_field(const char *type)
 {
 	if (strchr(type, '[') && strstr(type, "char"))
 		return 1;

 	return 0;
 }

 int filter_add_pred(struct ftrace_event_call *call, struct filter_pred *pred)
 {
 	struct ftrace_event_field *field;

 	field = find_event_field(call, pred->field_name);
 	if (!field)
 		return -EINVAL;

 	pred->offset = field->offset;

 	if (is_string_field(field->type)) {
 		if (!pred->str_val)
 			return -EINVAL;
 		pred->fn = filter_pred_string;
 		pred->str_len = field->size;
 		return __filter_add_pred(call, pred);
 	} else {
 		if (pred->str_val)
 			return -EINVAL;
 	}

 	switch (field->size) {
 	case 8:
 		pred->fn = filter_pred_64;
 		break;
 	case 4:
 		pred->fn = filter_pred_32;
 		break;
 	case 2:
 		pred->fn = filter_pred_16;
 		break;
 	case 1:
 		pred->fn = filter_pred_8;
 		break;
 	default:
 		return -EINVAL;
 	}

 	return __filter_add_pred(call, pred);
 }

 static struct filter_pred *copy_pred(struct filter_pred *pred)
 {
 	struct filter_pred *new_pred = kmalloc(sizeof(*pred), GFP_KERNEL);
 	if (!new_pred)
 		return NULL;

 	memcpy(new_pred, pred, sizeof(*pred));

 	if (pred->field_name) {
 		new_pred->field_name = kstrdup(pred->field_name, GFP_KERNEL);
 		if (!new_pred->field_name) {
 			kfree(new_pred);
 			return NULL;
 		}
 	}

 	if (pred->str_val) {
 		new_pred->str_val = kstrdup(pred->str_val, GFP_KERNEL);
 		if (!new_pred->str_val) {
 			filter_free_pred(new_pred);
 			return NULL;
 		}
 	}

 	return new_pred;
 }

 int filter_add_subsystem_pred(struct event_subsystem *system,
 			      struct filter_pred *pred)
 {
 	struct ftrace_event_call *call = __start_ftrace_events;
 	struct filter_pred *event_pred;
 	int i;

 	if (system->preds && !pred->compound)
 		filter_free_subsystem_preds(system);

 	if (!system->preds) {
 		system->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
 					GFP_KERNEL);
 		if (!system->preds)
 			return -ENOMEM;
 	}

 	for (i = 0; i < MAX_FILTER_PRED; i++) {
 		if (!system->preds[i]) {
 			system->preds[i] = pred;
 			break;
 		}
 	}

 	if (i == MAX_FILTER_PRED)
 		return -ENOSPC;

 	events_for_each(call) {
 		int err;

 		if (!call->name || !call->regfunc)
 			continue;

 		if (strcmp(call->system, system->name))
 			continue;

 		if (!find_event_field(call, pred->field_name))
 			continue;

 		event_pred = copy_pred(pred);
 		if (!event_pred)
 			goto oom;

 		err = filter_add_pred(call, event_pred);
 		if (err)
 			filter_free_pred(event_pred);
 		if (err == -ENOMEM)
 			goto oom;
 	}

 	return 0;

 oom:
 	system->preds[i] = NULL;
 	return -ENOMEM;
 }

 int filter_parse(char **pbuf, struct filter_pred *pred)
 {
 	char *tmp, *tok, *val_str = NULL;
 	int tok_n = 0;

 	/* field ==/!= number, or/and field ==/!= number, number */
 	while ((tok = strsep(pbuf, " \n"))) {
 		if (tok_n == 0) {
 			if (!strcmp(tok, "0")) {
 				pred->clear = 1;
 				return 0;
 			} else if (!strcmp(tok, "&&")) {
 				pred->or = 0;
 				pred->compound = 1;
 			} else if (!strcmp(tok, "||")) {
 				pred->or = 1;
 				pred->compound = 1;
 			} else
 				pred->field_name = tok;
 			tok_n = 1;
 			continue;
 		}
 		if (tok_n == 1) {
 			if (!pred->field_name)
 				pred->field_name = tok;
 			else if (!strcmp(tok, "!="))
 				pred->not = 1;
 			else if (!strcmp(tok, "=="))
 				pred->not = 0;
 			else {
 				pred->field_name = NULL;
 				return -EINVAL;
 			}
 			tok_n = 2;
 			continue;
 		}
 		if (tok_n == 2) {
 			if (pred->compound) {
 				if (!strcmp(tok, "!="))
 					pred->not = 1;
 				else if (!strcmp(tok, "=="))
 					pred->not = 0;
 				else {
 					pred->field_name = NULL;
 					return -EINVAL;
 				}
 			} else {
 				val_str = tok;
 				break; /* done */
 			}
 			tok_n = 3;
 			continue;
 		}
 		if (tok_n == 3) {
 			val_str = tok;
 			break; /* done */
 		}
 	}

 	if (!val_str) {
 		pred->field_name = NULL;
 		return -EINVAL;
 	}

 	pred->field_name = kstrdup(pred->field_name, GFP_KERNEL);
 	if (!pred->field_name)
 		return -ENOMEM;

 	pred->val = simple_strtoull(val_str, &tmp, 0);
 	if (tmp == val_str) {
 		pred->str_val = kstrdup(val_str, GFP_KERNEL);
 		if (!pred->str_val)
 			return -ENOMEM;
 	} else if (*tmp != '\0')
 		return -EINVAL;

 	return 0;
 }
	/*
	* trace_events_filter - generic event filtering
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	*
	* Copyright (C) 2009 Tom Zanussi <tzanussi@gmail.com>
	*/

	#include <linux/debugfs.h>
	#include <linux/uaccess.h>
	#include <linux/module.h>
	#include <linux/ctype.h>

	#include "trace.h"
	#include "trace_output.h"

	static int filter_pred_64(struct filter_pred pred, void event)
	{
	u64 addr = (u64 )(event + pred->offset);
	u64 val = (u64)pred->val;
	int match;

	match = (val == *addr) ^ pred->not;

	return match;
	}

	static int filter_pred_32(struct filter_pred pred, void event)
	{
	u32 addr = (u32 )(event + pred->offset);
	u32 val = (u32)pred->val;
	int match;

	match = (val == *addr) ^ pred->not;

	return match;
	}

	static int filter_pred_16(struct filter_pred pred, void event)
	{
	u16 addr = (u16 )(event + pred->offset);
	u16 val = (u16)pred->val;
	int match;

	match = (val == *addr) ^ pred->not;

	return match;
	}

	static int filter_pred_8(struct filter_pred pred, void event)
	{
	u8 addr = (u8 )(event + pred->offset);
	u8 val = (u8)pred->val;
	int match;

	match = (val == *addr) ^ pred->not;

	return match;
	}

	static int filter_pred_string(struct filter_pred pred, void event)
	{
	char addr = (char )(event + pred->offset);
	int cmp, match;

	cmp = strncmp(addr, pred->str_val, pred->str_len);

	match = (!cmp) ^ pred->not;

	return match;
	}

	/* return 1 if event matches, 0 otherwise (discard) */
	int filter_match_preds(struct ftrace_event_call call, void rec)
	{
	int i, matched, and_failed = 0;
	struct filter_pred *pred;

	for (i = 0; i < MAX_FILTER_PRED; i++) {
	if (call->preds[i]) {
	pred = call->preds[i];
	if (and_failed && !pred->or)
	continue;
	matched = pred->fn(pred, rec);
	if (!matched && !pred->or) {
	and_failed = 1;
	continue;
	} else if (matched && pred->or)
	return 1;
	} else
	break;
	}

	if (and_failed)
	return 0;

	return 1;
	}

	void filter_print_preds(struct filter_pred *preds, struct trace_seq s)
	{
	char *field_name;
	struct filter_pred *pred;
	int i;

	if (!preds) {
	trace_seq_printf(s, "none\n");
	return;
	}

	for (i = 0; i < MAX_FILTER_PRED; i++) {
	if (preds[i]) {
	pred = preds[i];
	field_name = pred->field_name;
	if (i)
	trace_seq_printf(s, pred->or ? "\|\| " : "&& ");
	trace_seq_printf(s, "%s ", field_name);
	trace_seq_printf(s, pred->not ? "!= " : "== ");
	if (pred->str_val)
	trace_seq_printf(s, "%s\n", pred->str_val);
	else
	trace_seq_printf(s, "%llu\n", pred->val);
	} else
	break;
	}
	}

	static struct ftrace_event_field *
	find_event_field(struct ftrace_event_call call, char name)
	{
	struct ftrace_event_field *field;

	list_for_each_entry(field, &call->fields, link) {
	if (!strcmp(field->name, name))
	return field;
	}

	return NULL;
	}

	void filter_free_pred(struct filter_pred *pred)
	{
	if (!pred)
	return;

	kfree(pred->field_name);
	kfree(pred->str_val);
	kfree(pred);
	}

	void filter_free_preds(struct ftrace_event_call *call)
	{
	int i;

	if (call->preds) {
	for (i = 0; i < MAX_FILTER_PRED; i++)
	filter_free_pred(call->preds[i]);
	kfree(call->preds);
	call->preds = NULL;
	}
	}

	void filter_free_subsystem_preds(struct event_subsystem *system)
	{
	struct ftrace_event_call *call = __start_ftrace_events;
	int i;

	if (system->preds) {
	for (i = 0; i < MAX_FILTER_PRED; i++)
	filter_free_pred(system->preds[i]);
	kfree(system->preds);
	system->preds = NULL;
	}

	events_for_each(call) {
	if (!call->name \|\| !call->regfunc)
	continue;

	if (!strcmp(call->system, system->name))
	filter_free_preds(call);
	}
	}

	static int __filter_add_pred(struct ftrace_event_call *call,
	struct filter_pred *pred)
	{
	int i;

	if (call->preds && !pred->compound)
	filter_free_preds(call);

	if (!call->preds) {
	call->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
	GFP_KERNEL);
	if (!call->preds)
	return -ENOMEM;
	}

	for (i = 0; i < MAX_FILTER_PRED; i++) {
	if (!call->preds[i]) {
	call->preds[i] = pred;
	return 0;
	}
	}

	return -ENOSPC;
	}

	static int is_string_field(const char *type)
	{
	if (strchr(type, '[') && strstr(type, "char"))
	return 1;

	return 0;
	}

	int filter_add_pred(struct ftrace_event_call call, struct filter_pred pred)
	{
	struct ftrace_event_field *field;

	field = find_event_field(call, pred->field_name);
	if (!field)
	return -EINVAL;

	pred->offset = field->offset;

	if (is_string_field(field->type)) {
	if (!pred->str_val)
	return -EINVAL;
	pred->fn = filter_pred_string;
	pred->str_len = field->size;
	return __filter_add_pred(call, pred);
	} else {
	if (pred->str_val)
	return -EINVAL;
	}

	switch (field->size) {
	case 8:
	pred->fn = filter_pred_64;
	break;
	case 4:
	pred->fn = filter_pred_32;
	break;
	case 2:
	pred->fn = filter_pred_16;
	break;
	case 1:
	pred->fn = filter_pred_8;
	break;
	default:
	return -EINVAL;
	}

	return __filter_add_pred(call, pred);
	}

	static struct filter_pred copy_pred(struct filter_pred pred)
	{
	struct filter_pred new_pred = kmalloc(sizeof(pred), GFP_KERNEL);
	if (!new_pred)
	return NULL;

	memcpy(new_pred, pred, sizeof(*pred));

	if (pred->field_name) {
	new_pred->field_name = kstrdup(pred->field_name, GFP_KERNEL);
	if (!new_pred->field_name) {
	kfree(new_pred);
	return NULL;
	}
	}

	if (pred->str_val) {
	new_pred->str_val = kstrdup(pred->str_val, GFP_KERNEL);
	if (!new_pred->str_val) {
	filter_free_pred(new_pred);
	return NULL;
	}
	}

	return new_pred;
	}

	int filter_add_subsystem_pred(struct event_subsystem *system,
	struct filter_pred *pred)
	{
	struct ftrace_event_call *call = __start_ftrace_events;
	struct filter_pred *event_pred;
	int i;

	if (system->preds && !pred->compound)
	filter_free_subsystem_preds(system);

	if (!system->preds) {
	system->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
	GFP_KERNEL);
	if (!system->preds)
	return -ENOMEM;
	}

	for (i = 0; i < MAX_FILTER_PRED; i++) {
	if (!system->preds[i]) {
	system->preds[i] = pred;
	break;
	}
	}

	if (i == MAX_FILTER_PRED)
	return -ENOSPC;

	events_for_each(call) {
	int err;

	if (!call->name \|\| !call->regfunc)
	continue;

	if (strcmp(call->system, system->name))
	continue;

	if (!find_event_field(call, pred->field_name))
	continue;

	event_pred = copy_pred(pred);
	if (!event_pred)
	goto oom;

	err = filter_add_pred(call, event_pred);
	if (err)
	filter_free_pred(event_pred);
	if (err == -ENOMEM)
	goto oom;
	}

	return 0;

	oom:
	system->preds[i] = NULL;
	return -ENOMEM;
	}

	int filter_parse(char *pbuf, struct filter_pred pred)
	{
	char tmp, tok, *val_str = NULL;
	int tok_n = 0;

	/* field ==/!= number, or/and field ==/!= number, number */
	while ((tok = strsep(pbuf, " \n"))) {
	if (tok_n == 0) {
	if (!strcmp(tok, "0")) {
	pred->clear = 1;
	return 0;
	} else if (!strcmp(tok, "&&")) {
	pred->or = 0;
	pred->compound = 1;
	} else if (!strcmp(tok, "\|\|")) {
	pred->or = 1;
	pred->compound = 1;
	} else
	pred->field_name = tok;
	tok_n = 1;
	continue;
	}
	if (tok_n == 1) {
	if (!pred->field_name)
	pred->field_name = tok;
	else if (!strcmp(tok, "!="))
	pred->not = 1;
	else if (!strcmp(tok, "=="))
	pred->not = 0;
	else {
	pred->field_name = NULL;
	return -EINVAL;
	}
	tok_n = 2;
	continue;
	}
	if (tok_n == 2) {
	if (pred->compound) {
	if (!strcmp(tok, "!="))
	pred->not = 1;
	else if (!strcmp(tok, "=="))
	pred->not = 0;
	else {
	pred->field_name = NULL;
	return -EINVAL;
	}
	} else {
	val_str = tok;
	break; /* done */
	}
	tok_n = 3;
	continue;
	}
	if (tok_n == 3) {
	val_str = tok;
	break; /* done */
	}
	}

	if (!val_str) {
	pred->field_name = NULL;
	return -EINVAL;
	}

	pred->field_name = kstrdup(pred->field_name, GFP_KERNEL);
	if (!pred->field_name)
	return -ENOMEM;

	pred->val = simple_strtoull(val_str, &tmp, 0);
	if (tmp == val_str) {
	pred->str_val = kstrdup(val_str, GFP_KERNEL);
	if (!pred->str_val)
	return -ENOMEM;
	} else if (*tmp != '\0')
	return -EINVAL;

	return 0;
	}