/*
 * 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/module.h>
#include <linux/ctype.h>
#include <linux/mutex.h>
#include <linux/perf_event.h>
#include <linux/slab.h>

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

#define DEFAULT_SYS_FILTER_MESSAGE                                      \
        "### global filter ###\n"                                       \
        "# Use this to set filters for multiple events.\n"              \
        "# Only events with the given fields will be affected.\n"       \
        "# If no events are modified, an error message will be displayed here"

enum filter_op_ids
{
        OP_OR,
        OP_AND,
        OP_GLOB,
        OP_NE,
        OP_EQ,
        OP_LT,
        OP_LE,
        OP_GT,
        OP_GE,
        OP_BAND,
        OP_NOT,
        OP_NONE,
        OP_OPEN_PAREN,
};

struct filter_op {
        int id;
        char *string;
        int precedence;
};

/* Order must be the same as enum filter_op_ids above */
static struct filter_op filter_ops[] = {
        { OP_OR,        "||",           1 },
        { OP_AND,       "&&",           2 },
        { OP_GLOB,      "~",            4 },
        { OP_NE,        "!=",           4 },
        { OP_EQ,        "==",           4 },
        { OP_LT,        "<",            5 },
        { OP_LE,        "<=",           5 },
        { OP_GT,        ">",            5 },
        { OP_GE,        ">=",           5 },
        { OP_BAND,      "&",            6 },
        { OP_NOT,       "!",            6 },
        { OP_NONE,      "OP_NONE",      0 },
        { OP_OPEN_PAREN, "(",           0 },
};

enum {
        FILT_ERR_NONE,
        FILT_ERR_INVALID_OP,
        FILT_ERR_UNBALANCED_PAREN,
        FILT_ERR_TOO_MANY_OPERANDS,
        FILT_ERR_OPERAND_TOO_LONG,
        FILT_ERR_FIELD_NOT_FOUND,
        FILT_ERR_ILLEGAL_FIELD_OP,
        FILT_ERR_ILLEGAL_INTVAL,
        FILT_ERR_BAD_SUBSYS_FILTER,
        FILT_ERR_TOO_MANY_PREDS,
        FILT_ERR_MISSING_FIELD,
        FILT_ERR_INVALID_FILTER,
        FILT_ERR_IP_FIELD_ONLY,
        FILT_ERR_ILLEGAL_NOT_OP,
};

static char *err_text[] = {
        "No error",
        "Invalid operator",
        "Unbalanced parens",
        "Too many operands",
        "Operand too long",
        "Field not found",
        "Illegal operation for field type",
        "Illegal integer value",
        "Couldn't find or set field in one of a subsystem's events",
        "Too many terms in predicate expression",
        "Missing field name and/or value",
        "Meaningless filter expression",
        "Only 'ip' field is supported for function trace",
        "Illegal use of '!'",
};

struct opstack_op {
        int op;
        struct list_head list;
};

struct postfix_elt {
        int op;
        char *operand;
        struct list_head list;
};

struct filter_parse_state {
        struct filter_op *ops;
        struct list_head opstack;
        struct list_head postfix;
        int lasterr;
        int lasterr_pos;

        struct {
                char *string;
                unsigned int cnt;
                unsigned int tail;
        } infix;

        struct {
                char string[MAX_FILTER_STR_VAL];
                int pos;
                unsigned int tail;
        } operand;
};

struct pred_stack {
        struct filter_pred      **preds;
        int                     index;
};

/* If not of not match is equal to not of not, then it is a match */
#define DEFINE_COMPARISON_PRED(type)                                    \
static int filter_pred_##type(struct filter_pred *pred, void *event)    \
{                                                                       \
        type *addr = (type *)(event + pred->offset);                    \
        type val = (type)pred->val;                                     \
        int match = 0;                                                  \
                                                                        \
        switch (pred->op) {                                             \
        case OP_LT:                                                     \
                match = (*addr < val);                                  \
                break;                                                  \
        case OP_LE:                                                     \
                match = (*addr <= val);                                 \
                break;                                                  \
        case OP_GT:                                                     \
                match = (*addr > val);                                  \
                break;                                                  \
        case OP_GE:                                                     \
                match = (*addr >= val);                                 \
                break;                                                  \
        case OP_BAND:                                                   \
                match = (*addr & val);                                  \
                break;                                                  \
        default:                                                        \
                break;                                                  \
        }                                                               \
                                                                        \
        return !!match == !pred->not;                                   \
}

#define DEFINE_EQUALITY_PRED(size)                                      \
static int filter_pred_##size(struct filter_pred *pred, void *event)    \
{                                                                       \
        u##size *addr = (u##size *)(event + pred->offset);              \
        u##size val = (u##size)pred->val;                               \
        int match;                                                      \
                                                                        \
        match = (val == *addr) ^ pred->not;                             \
                                                                        \
        return match;                                                   \
}

DEFINE_COMPARISON_PRED(s64);
DEFINE_COMPARISON_PRED(u64);
DEFINE_COMPARISON_PRED(s32);
DEFINE_COMPARISON_PRED(u32);
DEFINE_COMPARISON_PRED(s16);
DEFINE_COMPARISON_PRED(u16);
DEFINE_COMPARISON_PRED(s8);
DEFINE_COMPARISON_PRED(u8);

DEFINE_EQUALITY_PRED(64);
DEFINE_EQUALITY_PRED(32);
DEFINE_EQUALITY_PRED(16);
DEFINE_EQUALITY_PRED(8);

/* Filter predicate for fixed sized arrays of characters */
static int filter_pred_string(struct filter_pred *pred, void *event)
{
        char *addr = (char *)(event + pred->offset);
        int cmp, match;

        cmp = pred->regex.match(addr, &pred->regex, pred->regex.field_len);

        match = cmp ^ pred->not;

        return match;
}

/* Filter predicate for char * pointers */
static int filter_pred_pchar(struct filter_pred *pred, void *event)
{
        char **addr = (char **)(event + pred->offset);
        int cmp, match;
        int len = strlen(*addr) + 1;    /* including tailing '\0' */

        cmp = pred->regex.match(*addr, &pred->regex, len);

        match = cmp ^ pred->not;

        return match;
}

/*
 * Filter predicate for dynamic sized arrays of characters.
 * These are implemented through a list of strings at the end
 * of the entry.
 * Also each of these strings have a field in the entry which
 * contains its offset from the beginning of the entry.
 * We have then first to get this field, dereference it
 * and add it to the address of the entry, and at last we have
 * the address of the string.
 */
static int filter_pred_strloc(struct filter_pred *pred, void *event)
{
        u32 str_item = *(u32 *)(event + pred->offset);
        int str_loc = str_item & 0xffff;
        int str_len = str_item >> 16;
        char *addr = (char *)(event + str_loc);
        int cmp, match;

        cmp = pred->regex.match(addr, &pred->regex, str_len);

        match = cmp ^ pred->not;

        return match;
}

/* Filter predicate for CPUs. */
static int filter_pred_cpu(struct filter_pred *pred, void *event)
{
        int cpu, cmp;
        int match = 0;

        cpu = raw_smp_processor_id();
        cmp = pred->val;

        switch (pred->op) {
        case OP_EQ:
                match = cpu == cmp;
                break;
        case OP_LT:
                match = cpu < cmp;
                break;
        case OP_LE:
                match = cpu <= cmp;
                break;
        case OP_GT:
                match = cpu > cmp;
                break;
        case OP_GE:
                match = cpu >= cmp;
                break;
        default:
                break;
        }

        return !!match == !pred->not;
}

/* Filter predicate for COMM. */
static int filter_pred_comm(struct filter_pred *pred, void *event)
{
        int cmp, match;

        cmp = pred->regex.match(current->comm, &pred->regex,
                                pred->regex.field_len);
        match = cmp ^ pred->not;

        return match;
}

static int filter_pred_none(struct filter_pred *pred, void *event)
{
        return 0;
}

/*
 * regex_match_foo - Basic regex callbacks
 *
 * @str: the string to be searched
 * @r:   the regex structure containing the pattern string
 * @len: the length of the string to be searched (including '\0')
 *
 * Note:
 * - @str might not be NULL-terminated if it's of type DYN_STRING
 *   or STATIC_STRING
 */

static int regex_match_full(char *str, struct regex *r, int len)
{
        if (strncmp(str, r->pattern, len) == 0)
                return 1;
        return 0;
}

static int regex_match_front(char *str, struct regex *r, int len)
{
        if (strncmp(str, r->pattern, r->len) == 0)
                return 1;
        return 0;
}

static int regex_match_middle(char *str, struct regex *r, int len)
{
        if (strnstr(str, r->pattern, len))
                return 1;
        return 0;
}

static int regex_match_end(char *str, struct regex *r, int len)
{
        int strlen = len - 1;

        if (strlen >= r->len &&
            memcmp(str + strlen - r->len, r->pattern, r->len) == 0)
                return 1;
        return 0;
}

/**
 * filter_parse_regex - parse a basic regex
 * @buff:   the raw regex
 * @len:    length of the regex
 * @search: will point to the beginning of the string to compare
 * @not:    tell whether the match will have to be inverted
 *
 * This passes in a buffer containing a regex and this function will
 * set search to point to the search part of the buffer and
 * return the type of search it is (see enum above).
 * This does modify buff.
 *
 * Returns enum type.
 *  search returns the pointer to use for comparison.
 *  not returns 1 if buff started with a '!'
 *     0 otherwise.
 */
enum regex_type filter_parse_regex(char *buff, int len, char **search, int *not)
{
        int type = MATCH_FULL;
        int i;

        if (buff[0] == '!') {
                *not = 1;
                buff++;
                len--;
        } else
                *not = 0;

        *search = buff;

        for (i = 0; i < len; i++) {
                if (buff[i] == '*') {
                        if (!i) {
                                *search = buff + 1;
                                type = MATCH_END_ONLY;
                        } else {
                                if (type == MATCH_END_ONLY)
                                        type = MATCH_MIDDLE_ONLY;
                                else
                                        type = MATCH_FRONT_ONLY;
                                buff[i] = 0;
                                break;
                        }
                }
        }

        return type;
}

static void filter_build_regex(struct filter_pred *pred)
{
        struct regex *r = &pred->regex;
        char *search;
        enum regex_type type = MATCH_FULL;
        int not = 0;

        if (pred->op == OP_GLOB) {
                type = filter_parse_regex(r->pattern, r->len, &search, &not);
                r->len = strlen(search);
                memmove(r->pattern, search, r->len+1);
        }

        switch (type) {
        case MATCH_FULL:
                r->match = regex_match_full;
                break;
        case MATCH_FRONT_ONLY:
                r->match = regex_match_front;
                break;
        case MATCH_MIDDLE_ONLY:
                r->match = regex_match_middle;
                break;
        case MATCH_END_ONLY:
                r->match = regex_match_end;
                break;
        }

        pred->not ^= not;
}

enum move_type {
        MOVE_DOWN,
        MOVE_UP_FROM_LEFT,
        MOVE_UP_FROM_RIGHT
};

static struct filter_pred *
get_pred_parent(struct filter_pred *pred, struct filter_pred *preds,
                int index, enum move_type *move)
{
        if (pred->parent & FILTER_PRED_IS_RIGHT)
                *move = MOVE_UP_FROM_RIGHT;
        else
                *move = MOVE_UP_FROM_LEFT;
        pred = &preds[pred->parent & ~FILTER_PRED_IS_RIGHT];

        return pred;
}

enum walk_return {
        WALK_PRED_ABORT,
        WALK_PRED_PARENT,
        WALK_PRED_DEFAULT,
};

typedef int (*filter_pred_walkcb_t) (enum move_type move,
                                     struct filter_pred *pred,
                                     int *err, void *data);

static int walk_pred_tree(struct filter_pred *preds,
                          struct filter_pred *root,
                          filter_pred_walkcb_t cb, void *data)
{
        struct filter_pred *pred = root;
        enum move_type move = MOVE_DOWN;
        int done = 0;

        if  (!preds)
                return -EINVAL;

        do {
                int err = 0, ret;

                ret = cb(move, pred, &err, data);
                if (ret == WALK_PRED_ABORT)
                        return err;
                if (ret == WALK_PRED_PARENT)
                        goto get_parent;

                switch (move) {
                case MOVE_DOWN:
                        if (pred->left != FILTER_PRED_INVALID) {
                                pred = &preds[pred->left];
                                continue;
                        }
                        goto get_parent;
                case MOVE_UP_FROM_LEFT:
                        pred = &preds[pred->right];
                        move = MOVE_DOWN;
                        continue;
                case MOVE_UP_FROM_RIGHT:
 get_parent:
                        if (pred == root)
                                break;
                        pred = get_pred_parent(pred, preds,
                                               pred->parent,
                                               &move);
                        continue;
                }
                done = 1;
        } while (!done);

        /* We are fine. */
        return 0;
}

/*
 * A series of AND or ORs where found together. Instead of
 * climbing up and down the tree branches, an array of the
 * ops were made in order of checks. We can just move across
 * the array and short circuit if needed.
 */
static int process_ops(struct filter_pred *preds,
                       struct filter_pred *op, void *rec)
{
        struct filter_pred *pred;
        int match = 0;
        int type;
        int i;

        /*
         * Micro-optimization: We set type to true if op
         * is an OR and false otherwise (AND). Then we
         * just need to test if the match is equal to
         * the type, and if it is, we can short circuit the
         * rest of the checks:
         *
         * if ((match && op->op == OP_OR) ||
         *     (!match && op->op == OP_AND))
         *        return match;
         */
        type = op->op == OP_OR;

        for (i = 0; i < op->val; i++) {
                pred = &preds[op->ops[i]];
                if (!WARN_ON_ONCE(!pred->fn))
                        match = pred->fn(pred, rec);
                if (!!match == type)
                        break;
        }
        /* If not of not match is equal to not of not, then it is a match */
        return !!match == !op->not;
}

struct filter_match_preds_data {
        struct filter_pred *preds;
        int match;
        void *rec;
};

static int filter_match_preds_cb(enum move_type move, struct filter_pred *pred,
                                 int *err, void *data)
{
        struct filter_match_preds_data *d = data;

        *err = 0;
        switch (move) {
        case MOVE_DOWN:
                /* only AND and OR have children */
                if (pred->left != FILTER_PRED_INVALID) {
                        /* If ops is set, then it was folded. */
                        if (!pred->ops)
                                return WALK_PRED_DEFAULT;
                        /* We can treat folded ops as a leaf node */
                        d->match = process_ops(d->preds, pred, d->rec);
                } else {
                        if (!WARN_ON_ONCE(!pred->fn))
                                d->match = pred->fn(pred, d->rec);
                }

                return WALK_PRED_PARENT;
        case MOVE_UP_FROM_LEFT:
                /*
                 * Check for short circuits.
                 *
                 * Optimization: !!match == (pred->op == OP_OR)
                 *   is the same as:
                 * if ((match && pred->op == OP_OR) ||
                 *     (!match && pred->op == OP_AND))
                 */
                if (!!d->match == (pred->op == OP_OR))
                        return WALK_PRED_PARENT;
                break;
        case MOVE_UP_FROM_RIGHT:
                break;
        }

        return WALK_PRED_DEFAULT;
}

/* return 1 if event matches, 0 otherwise (discard) */
int filter_match_preds(struct event_filter *filter, void *rec)
{
        struct filter_pred *preds;
        struct filter_pred *root;
        struct filter_match_preds_data data = {
                /* match is currently meaningless */
                .match = -1,
                .rec   = rec,
        };
        int n_preds, ret;

        /* no filter is considered a match */
        if (!filter)
                return 1;

        n_preds = filter->n_preds;
        if (!n_preds)
                return 1;

        /*
         * n_preds, root and filter->preds are protect with preemption disabled.
         */
        root = rcu_dereference_sched(filter->root);
        if (!root)
                return 1;

        data.preds = preds = rcu_dereference_sched(filter->preds);
        ret = walk_pred_tree(preds, root, filter_match_preds_cb, &data);
        WARN_ON(ret);
        return data.match;
}
EXPORT_SYMBOL_GPL(filter_match_preds);

static void parse_error(struct filter_parse_state *ps, int err, int pos)
{
        ps->lasterr = err;
        ps->lasterr_pos = pos;
}

static void remove_filter_string(struct event_filter *filter)
{
        if (!filter)
                return;

        kfree(filter->filter_string);
        filter->filter_string = NULL;
}

static int replace_filter_string(struct event_filter *filter,
                                 char *filter_string)
{
        kfree(filter->filter_string);
        filter->filter_string = kstrdup(filter_string, GFP_KERNEL);
        if (!filter->filter_string)
                return -ENOMEM;

        return 0;
}

static int append_filter_string(struct event_filter *filter,
                                char *string)
{
        int newlen;
        char *new_filter_string;

        BUG_ON(!filter->filter_string);
        newlen = strlen(filter->filter_string) + strlen(string) + 1;
        new_filter_string = kmalloc(newlen, GFP_KERNEL);
        if (!new_filter_string)
                return -ENOMEM;

        strcpy(new_filter_string, filter->filter_string);
        strcat(new_filter_string, string);
        kfree(filter->filter_string);
        filter->filter_string = new_filter_string;

        return 0;
}

static void append_filter_err(struct filter_parse_state *ps,
                              struct event_filter *filter)
{
        int pos = ps->lasterr_pos;
        char *buf, *pbuf;

        buf = (char *)__get_free_page(GFP_TEMPORARY);
        if (!buf)
                return;

        append_filter_string(filter, "\n");
        memset(buf, ' ', PAGE_SIZE);
        if (pos > PAGE_SIZE - 128)
                pos = 0;
        buf[pos] = '^';
        pbuf = &buf[pos] + 1;

        sprintf(pbuf, "\nparse_error: %s\n", err_text[ps->lasterr]);
        append_filter_string(filter, buf);
        free_page((unsigned long) buf);
}

static inline struct event_filter *event_filter(struct trace_event_file *file)
{
        if (file->event_call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
                return file->event_call->filter;
        else
                return file->filter;
}

/* caller must hold event_mutex */
void print_event_filter(struct trace_event_file *file, struct trace_seq *s)
{
        struct event_filter *filter = event_filter(file);

        if (filter && filter->filter_string)
                trace_seq_printf(s, "%s\n", filter->filter_string);
        else
                trace_seq_puts(s, "none\n");
}

void print_subsystem_event_filter(struct event_subsystem *system,
                                  struct trace_seq *s)
{
        struct event_filter *filter;

        mutex_lock(&event_mutex);
        filter = system->filter;
        if (filter && filter->filter_string)
                trace_seq_printf(s, "%s\n", filter->filter_string);
        else
                trace_seq_puts(s, DEFAULT_SYS_FILTER_MESSAGE "\n");
        mutex_unlock(&event_mutex);
}

static int __alloc_pred_stack(struct pred_stack *stack, int n_preds)
{
        stack->preds = kcalloc(n_preds + 1, sizeof(*stack->preds), GFP_KERNEL);
        if (!stack->preds)
                return -ENOMEM;
        stack->index = n_preds;
        return 0;
}

static void __free_pred_stack(struct pred_stack *stack)
{
        kfree(stack->preds);
        stack->index = 0;
}

static int __push_pred_stack(struct pred_stack *stack,
                             struct filter_pred *pred)
{
        int index = stack->index;

        if (WARN_ON(index == 0))
                return -ENOSPC;

        stack->preds[--index] = pred;
        stack->index = index;
        return 0;
}

static struct filter_pred *
__pop_pred_stack(struct pred_stack *stack)
{
        struct filter_pred *pred;
        int index = stack->index;

        pred = stack->preds[index++];
        if (!pred)
                return NULL;

        stack->index = index;
        return pred;
}

static int filter_set_pred(struct event_filter *filter,
                           int idx,
                           struct pred_stack *stack,
                           struct filter_pred *src)
{
        struct filter_pred *dest = &filter->preds[idx];
        struct filter_pred *left;
        struct filter_pred *right;

        *dest = *src;
        dest->index = idx;

        if (dest->op == OP_OR || dest->op == OP_AND) {
                right = __pop_pred_stack(stack);
                left = __pop_pred_stack(stack);
                if (!left || !right)
                        return -EINVAL;
                /*
                 * If both children can be folded
                 * and they are the same op as this op or a leaf,
                 * then this op can be folded.
                 */
                if (left->index & FILTER_PRED_FOLD &&
                    ((left->op == dest->op && !left->not) ||
                     left->left == FILTER_PRED_INVALID) &&
                    right->index & FILTER_PRED_FOLD &&
                    ((right->op == dest->op && !right->not) ||
                     right->left == FILTER_PRED_INVALID))
                        dest->index |= FILTER_PRED_FOLD;

                dest->left = left->index & ~FILTER_PRED_FOLD;
                dest->right = right->index & ~FILTER_PRED_FOLD;
                left->parent = dest->index & ~FILTER_PRED_FOLD;
                right->parent = dest->index | FILTER_PRED_IS_RIGHT;
        } else {
                /*
                 * Make dest->left invalid to be used as a quick
                 * way to know this is a leaf node.
                 */
                dest->left = FILTER_PRED_INVALID;

                /* All leafs allow folding the parent ops. */
                dest->index |= FILTER_PRED_FOLD;
        }

        return __push_pred_stack(stack, dest);
}

static void __free_preds(struct event_filter *filter)
{
        int i;

        if (filter->preds) {
                for (i = 0; i < filter->n_preds; i++)
                        kfree(filter->preds[i].ops);
                kfree(filter->preds);
                filter->preds = NULL;
        }
        filter->a_preds = 0;
        filter->n_preds = 0;
}

static void filter_disable(struct trace_event_file *file)
{
        struct trace_event_call *call = file->event_call;

        if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
                call->flags &= ~TRACE_EVENT_FL_FILTERED;
        else
                file->flags &= ~EVENT_FILE_FL_FILTERED;
}

static void __free_filter(struct event_filter *filter)
{
        if (!filter)
                return;

        __free_preds(filter);
        kfree(filter->filter_string);
        kfree(filter);
}

void free_event_filter(struct event_filter *filter)
{
        __free_filter(filter);
}

static struct event_filter *__alloc_filter(void)
{
        struct event_filter *filter;

        filter = kzalloc(sizeof(*filter), GFP_KERNEL);
        return filter;
}

static int __alloc_preds(struct event_filter *filter, int n_preds)
{
        struct filter_pred *pred;
        int i;

        if (filter->preds)
                __free_preds(filter);

        filter->preds = kcalloc(n_preds, sizeof(*filter->preds), GFP_KERNEL);

        if (!filter->preds)
                return -ENOMEM;

        filter->a_preds = n_preds;
        filter->n_preds = 0;

        for (i = 0; i < n_preds; i++) {
                pred = &filter->preds[i];
                pred->fn = filter_pred_none;
        }

        return 0;
}

static inline void __remove_filter(struct trace_event_file *file)
{
        struct trace_event_call *call = file->event_call;

        filter_disable(file);
        if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
                remove_filter_string(call->filter);
        else
                remove_filter_string(file->filter);
}

static void filter_free_subsystem_preds(struct trace_subsystem_dir *dir,
                                        struct trace_array *tr)
{
        struct trace_event_file *file;

        list_for_each_entry(file, &tr->events, list) {
                if (file->system != dir)
                        continue;
                __remove_filter(file);
        }
}

static inline void __free_subsystem_filter(struct trace_event_file *file)
{
        struct trace_event_call *call = file->event_call;

        if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER) {
                __free_filter(call->filter);
                call->filter = NULL;
        } else {
                __free_filter(file->filter);
                file->filter = NULL;
        }
}

static void filter_free_subsystem_filters(struct trace_subsystem_dir *dir,
                                          struct trace_array *tr)
{
        struct trace_event_file *file;

        list_for_each_entry(file, &tr->events, list) {
                if (file->system != dir)
                        continue;
                __free_subsystem_filter(file);
        }
}

static int filter_add_pred(struct filter_parse_state *ps,
                           struct event_filter *filter,
                           struct filter_pred *pred,
                           struct pred_stack *stack)
{
        int err;

        if (WARN_ON(filter->n_preds == filter->a_preds)) {
                parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0);
                return -ENOSPC;
        }

        err = filter_set_pred(filter, filter->n_preds, stack, pred);
        if (err)
                return err;

        filter->n_preds++;

        return 0;
}

int filter_assign_type(const char *type)
{
        if (strstr(type, "__data_loc") && strstr(type, "char"))
                return FILTER_DYN_STRING;

        if (strchr(type, '[') && strstr(type, "char"))
                return FILTER_STATIC_STRING;

        return FILTER_OTHER;
}

static bool is_legal_op(struct ftrace_event_field *field, int op)
{
        if (is_string_field(field) &&
            (op != OP_EQ && op != OP_NE && op != OP_GLOB))
                return false;
        if (!is_string_field(field) && op == OP_GLOB)
                return false;

        return true;
}

static filter_pred_fn_t select_comparison_fn(int op, int field_size,
                                             int field_is_signed)
{
        filter_pred_fn_t fn = NULL;

        switch (field_size) {
        case 8:
                if (op == OP_EQ || op == OP_NE)
                        fn = filter_pred_64;
                else if (field_is_signed)
                        fn = filter_pred_s64;
                else
                        fn = filter_pred_u64;
                break;
        case 4:
                if (op == OP_EQ || op == OP_NE)
                        fn = filter_pred_32;
                else if (field_is_signed)
                        fn = filter_pred_s32;
                else
                        fn = filter_pred_u32;
                break;
        case 2:
                if (op == OP_EQ || op == OP_NE)
                        fn = filter_pred_16;
                else if (field_is_signed)

                        fn = filter_pred_s16;
                else
                        fn = filter_pred_u16;
                break;
        case 1:
                if (op == OP_EQ || op == OP_NE)
                        fn = filter_pred_8;
                else if (field_is_signed)
                        fn = filter_pred_s8;
                else
                        fn = filter_pred_u8;
                break;
        }

        return fn;
}

static int init_pred(struct filter_parse_state *ps,
                     struct ftrace_event_field *field,
                     struct filter_pred *pred)

{
        filter_pred_fn_t fn = filter_pred_none;
        unsigned long long val;
        int ret;

        pred->offset = field->offset;

        if (!is_legal_op(field, pred->op)) {
                parse_error(ps, FILT_ERR_ILLEGAL_FIELD_OP, 0);
                return -EINVAL;
        }

        if (field->filter_type == FILTER_COMM) {
                filter_build_regex(pred);
                fn = filter_pred_comm;
                pred->regex.field_len = TASK_COMM_LEN;
        } else if (is_string_field(field)) {
                filter_build_regex(pred);

                if (field->filter_type == FILTER_STATIC_STRING) {
                        fn = filter_pred_string;
                        pred->regex.field_len = field->size;
                } else if (field->filter_type == FILTER_DYN_STRING)
                        fn = filter_pred_strloc;
                else
                        fn = filter_pred_pchar;
        } else if (is_function_field(field)) {
                if (strcmp(field->name, "ip")) {
                        parse_error(ps, FILT_ERR_IP_FIELD_ONLY, 0);
                        return -EINVAL;
                }
        } else {
                if (field->is_signed)
                        ret = kstrtoll(pred->regex.pattern, 0, &val);
                else
                        ret = kstrtoull(pred->regex.pattern, 0, &val);
                if (ret) {
                        parse_error(ps, FILT_ERR_ILLEGAL_INTVAL, 0);
                        return -EINVAL;
                }
                pred->val = val;

                if (field->filter_type == FILTER_CPU)
                        fn = filter_pred_cpu;
                else
                        fn = select_comparison_fn(pred->op, field->size,
                                          field->is_signed);
                if (!fn) {
                        parse_error(ps, FILT_ERR_INVALID_OP, 0);
                        return -EINVAL;
                }
        }

        if (pred->op == OP_NE)
                pred->not ^= 1;

        pred->fn = fn;
        return 0;
}

static void parse_init(struct filter_parse_state *ps,
                       struct filter_op *ops,
                       char *infix_string)
{
        memset(ps, '\0', sizeof(*ps));

        ps->infix.string = infix_string;
        ps->infix.cnt = strlen(infix_string);
        ps->ops = ops;

        INIT_LIST_HEAD(&ps->opstack);
        INIT_LIST_HEAD(&ps->postfix);
}

static char infix_next(struct filter_parse_state *ps)
{
        if (!ps->infix.cnt)
                return 0;

        ps->infix.cnt--;

        return ps->infix.string[ps->infix.tail++];
}

static char infix_peek(struct filter_parse_state *ps)
{
        if (ps->infix.tail == strlen(ps->infix.string))
                return 0;

        return ps->infix.string[ps->infix.tail];
}

static void infix_advance(struct filter_parse_state *ps)
{
        if (!ps->infix.cnt)
                return;

        ps->infix.cnt--;
        ps->infix.tail++;
}

static inline int is_precedence_lower(struct filter_parse_state *ps,
                                      int a, int b)
{
        return ps->ops[a].precedence < ps->ops[b].precedence;
}

static inline int is_op_char(struct filter_parse_state *ps, char c)
{
        int i;

        for (i = 0; strcmp(ps->ops[i].string, "OP_NONE"); i++) {
                if (ps->ops[i].string[0] == c)
                        return 1;
        }

        return 0;
}

static int infix_get_op(struct filter_parse_state *ps, char firstc)
{
        char nextc = infix_peek(ps);
        char opstr[3];
        int i;

        opstr[0] = firstc;
        opstr[1] = nextc;
        opstr[2] = '\0';

        for (i = 0; strcmp(ps->ops[i].string, "OP_NONE"); i++) {
                if (!strcmp(opstr, ps->ops[i].string)) {
                        infix_advance(ps);
                        return ps->ops[i].id;
                }
        }

        opstr[1] = '\0';

        for (i = 0; strcmp(ps->ops[i].string, "OP_NONE"); i++) {
                if (!strcmp(opstr, ps->ops[i].string))
                        return ps->ops[i].id;
        }

        return OP_NONE;
}

static inline void clear_operand_string(struct filter_parse_state *ps)
{
        memset(ps->operand.string, '\0', MAX_FILTER_STR_VAL);
        ps->operand.tail = 0;
}

static inline int append_operand_char(struct filter_parse_state *ps, char c)
{
        if (ps->operand.tail == MAX_FILTER_STR_VAL - 1)
                return -EINVAL;

        ps->operand.string[ps->operand.tail++] = c;

        return 0;
}

static int filter_opstack_push(struct filter_parse_state *ps, int op)
{
        struct opstack_op *opstack_op;

        opstack_op = kmalloc(sizeof(*opstack_op), GFP_KERNEL);
        if (!opstack_op)
                return -ENOMEM;

        opstack_op->op = op;
        list_add(&opstack_op->list, &ps->opstack);

        return 0;
}

static int filter_opstack_empty(struct filter_parse_state *ps)
{
        return list_empty(&ps->opstack);
}

static int filter_opstack_top(struct filter_parse_state *ps)
{
        struct opstack_op *opstack_op;

        if (filter_opstack_empty(ps))
                return OP_NONE;

        opstack_op = list_first_entry(&ps->opstack, struct opstack_op, list);

        return opstack_op->op;
}

static int filter_opstack_pop(struct filter_parse_state *ps)
{
        struct opstack_op *opstack_op;
        int op;

        if (filter_opstack_empty(ps))
                return OP_NONE;

        opstack_op = list_first_entry(&ps->opstack, struct opstack_op, list);
        op = opstack_op->op;
        list_del(&opstack_op->list);

        kfree(opstack_op);

        return op;
}

static void filter_opstack_clear(struct filter_parse_state *ps)
{
        while (!filter_opstack_empty(ps))
                filter_opstack_pop(ps);
}

static char *curr_operand(struct filter_parse_state *ps)
{
        return ps->operand.string;
}

static int postfix_append_operand(struct filter_parse_state *ps, char *operand)
{
        struct postfix_elt *elt;

        elt = kmalloc(sizeof(*elt), GFP_KERNEL);
        if (!elt)
                return -ENOMEM;

        elt->op = OP_NONE;
        elt->operand = kstrdup(operand, GFP_KERNEL);
        if (!elt->operand) {
                kfree(elt);
                return -ENOMEM;
        }

        list_add_tail(&elt->list, &ps->postfix);

        return 0;
}

static int postfix_append_op(struct filter_parse_state *ps, int op)
{
        struct postfix_elt *elt;

        elt = kmalloc(sizeof(*elt), GFP_KERNEL);
        if (!elt)
                return -ENOMEM;

        elt->op = op;
        elt->operand = NULL;

        list_add_tail(&elt->list, &ps->postfix);

        return 0;
}

static void postfix_clear(struct filter_parse_state *ps)
{
        struct postfix_elt *elt;

        while (!list_empty(&ps->postfix)) {
                elt = list_first_entry(&ps->postfix, struct postfix_elt, list);
                list_del(&elt->list);
                kfree(elt->operand);
                kfree(elt);
        }
}

static int filter_parse(struct filter_parse_state *ps)
{
        int in_string = 0;
        int op, top_op;
        char ch;

        while ((ch = infix_next(ps))) {
                if (ch == '"') {
                        in_string ^= 1;
                        continue;
                }

                if (in_string)
                        goto parse_operand;

                if (isspace(ch))
                        continue;

                if (is_op_char(ps, ch)) {
                        op = infix_get_op(ps, ch);
                        if (op == OP_NONE) {
                                parse_error(ps, FILT_ERR_INVALID_OP, 0);
                                return -EINVAL;
                        }

                        if (strlen(curr_operand(ps))) {
                                postfix_append_operand(ps, curr_operand(ps));
                                clear_operand_string(ps);
                        }

                        while (!filter_opstack_empty(ps)) {
                                top_op = filter_opstack_top(ps);
                                if (!is_precedence_lower(ps, top_op, op)) {
                                        top_op = filter_opstack_pop(ps);
                                        postfix_append_op(ps, top_op);
                                        continue;
                                }
                                break;
                        }

                        filter_opstack_push(ps, op);
                        continue;
                }

                if (ch == '(') {
                        filter_opstack_push(ps, OP_OPEN_PAREN);
                        continue;
                }

                if (ch == ')') {
                        if (strlen(curr_operand(ps))) {
                                postfix_append_operand(ps, curr_operand(ps));
                                clear_operand_string(ps);
                        }

                        top_op = filter_opstack_pop(ps);
                        while (top_op != OP_NONE) {
                                if (top_op == OP_OPEN_PAREN)
                                        break;
                                postfix_append_op(ps, top_op);
                                top_op = filter_opstack_pop(ps);
                        }
                        if (top_op == OP_NONE) {
                                parse_error(ps, FILT_ERR_UNBALANCED_PAREN, 0);
                                return -EINVAL;
                        }
                        continue;
                }
parse_operand:
                if (append_operand_char(ps, ch)) {
                        parse_error(ps, FILT_ERR_OPERAND_TOO_LONG, 0);
                        return -EINVAL;
                }
        }

        if (strlen(curr_operand(ps)))
                postfix_append_operand(ps, curr_operand(ps));

        while (!filter_opstack_empty(ps)) {
                top_op = filter_opstack_pop(ps);
                if (top_op == OP_NONE)
                        break;
                if (top_op == OP_OPEN_PAREN) {
                        parse_error(ps, FILT_ERR_UNBALANCED_PAREN, 0);
                        return -EINVAL;
                }
                postfix_append_op(ps, top_op);
        }

        return 0;
}

static struct filter_pred *create_pred(struct filter_parse_state *ps,
                                       struct trace_event_call *call,
                                       int op, char *operand1, char *operand2)
{
        struct ftrace_event_field *field;
        static struct filter_pred pred;

        memset(&pred, 0, sizeof(pred));
        pred.op = op;

        if (op == OP_AND || op == OP_OR)
                return &pred;

        if (!operand1 || !operand2) {
                parse_error(ps, FILT_ERR_MISSING_FIELD, 0);
                return NULL;
        }

        field = trace_find_event_field(call, operand1);
        if (!field) {
                parse_error(ps, FILT_ERR_FIELD_NOT_FOUND, 0);
                return NULL;
        }

        strcpy(pred.regex.pattern, operand2);
        pred.regex.len = strlen(pred.regex.pattern);
        pred.field = field;
        return init_pred(ps, field, &pred) ? NULL : &pred;
}

static int check_preds(struct filter_parse_state *ps)
{
        int n_normal_preds = 0, n_logical_preds = 0;
        struct postfix_elt *elt;
        int cnt = 0;

        list_for_each_entry(elt, &ps->postfix, list) {
                if (elt->op == OP_NONE) {
                        cnt++;
                        continue;
                }

                if (elt->op == OP_AND || elt->op == OP_OR) {
                        n_logical_preds++;
                        cnt--;
                        continue;
                }
                if (elt->op != OP_NOT)
                        cnt--;
                n_normal_preds++;
                /* all ops should have operands */
                if (cnt < 0)
                        break;
        }

        if (cnt != 1 || !n_normal_preds || n_logical_preds >= n_normal_preds) {
                parse_error(ps, FILT_ERR_INVALID_FILTER, 0);
                return -EINVAL;
        }

        return 0;
}

static int count_preds(struct filter_parse_state *ps)
{
        struct postfix_elt *elt;
        int n_preds = 0;

        list_for_each_entry(elt, &ps->postfix, list) {
                if (elt->op == OP_NONE)
                        continue;
                n_preds++;
        }

        return n_preds;
}

struct check_pred_data {
        int count;
        int max;
};

static int check_pred_tree_cb(enum move_type move, struct filter_pred *pred,
                              int *err, void *data)
{
        struct check_pred_data *d = data;

        if (WARN_ON(d->count++ > d->max)) {
                *err = -EINVAL;
                return WALK_PRED_ABORT;
        }
        return WALK_PRED_DEFAULT;
}

/*
 * The tree is walked at filtering of an event. If the tree is not correctly
 * built, it may cause an infinite loop. Check here that the tree does
 * indeed terminate.
 */
static int check_pred_tree(struct event_filter *filter,
                           struct filter_pred *root)
{
        struct check_pred_data data = {
                /*
                 * The max that we can hit a node is three times.
                 * Once going down, once coming up from left, and
                 * once coming up from right. This is more than enough
                 * since leafs are only hit a single time.
                 */
                .max   = 3 * filter->n_preds,
                .count = 0,
        };

        return walk_pred_tree(filter->preds, root,
                              check_pred_tree_cb, &data);
}

static int count_leafs_cb(enum move_type move, struct filter_pred *pred,
                          int *err, void *data)
{
        int *count = data;

        if ((move == MOVE_DOWN) &&
            (pred->left == FILTER_PRED_INVALID))
                (*count)++;

        return WALK_PRED_DEFAULT;
}

static int count_leafs(struct filter_pred *preds, struct filter_pred *root)
{
        int count = 0, ret;

        ret = walk_pred_tree(preds, root, count_leafs_cb, &count);
        WARN_ON(ret);
        return count;
}

struct fold_pred_data {
        struct filter_pred *root;
        int count;
        int children;
};

static int fold_pred_cb(enum move_type move, struct filter_pred *pred,
                        int *err, void *data)
{
        struct fold_pred_data *d = data;
        struct filter_pred *root = d->root;

        if (move != MOVE_DOWN)
                return WALK_PRED_DEFAULT;
        if (pred->left != FILTER_PRED_INVALID)
                return WALK_PRED_DEFAULT;

        if (WARN_ON(d->count == d->children)) {
                *err = -EINVAL;
                return WALK_PRED_ABORT;
        }

        pred->index &= ~FILTER_PRED_FOLD;
        root->ops[d->count++] = pred->index;
        return WALK_PRED_DEFAULT;
}

static int fold_pred(struct filter_pred *preds, struct filter_pred *root)
{
        struct fold_pred_data data = {
                .root  = root,
                .count = 0,
        };
        int children;

        /* No need to keep the fold flag */
        root->index &= ~FILTER_PRED_FOLD;

        /* If the root is a leaf then do nothing */
        if (root->left == FILTER_PRED_INVALID)
                return 0;

        /* count the children */
        children = count_leafs(preds, &preds[root->left]);
        children += count_leafs(preds, &preds[root->right]);

        root->ops = kcalloc(children, sizeof(*root->ops), GFP_KERNEL);
        if (!root->ops)
                return -ENOMEM;

        root->val = children;
        data.children = children;
        return walk_pred_tree(preds, root, fold_pred_cb, &data);
}

static int fold_pred_tree_cb(enum move_type move, struct filter_pred *pred,
                             int *err, void *data)
{
        struct filter_pred *preds = data;

        if (move != MOVE_DOWN)
                return WALK_PRED_DEFAULT;
        if (!(pred->index & FILTER_PRED_FOLD))
                return WALK_PRED_DEFAULT;

        *err = fold_pred(preds, pred);
        if (*err)
                return WALK_PRED_ABORT;

        /* eveyrhing below is folded, continue with parent */
        return WALK_PRED_PARENT;
}

/*
 * To optimize the processing of the ops, if we have several "ors" or
 * "ands" together, we can put them in an array and process them all
 * together speeding up the filter logic.
 */
static int fold_pred_tree(struct event_filter *filter,
                           struct filter_pred *root)
{
        return walk_pred_tree(filter->preds, root, fold_pred_tree_cb,
                              filter->preds);
}

static int replace_preds(struct trace_event_call *call,
                         struct event_filter *filter,
                         struct filter_parse_state *ps,
                         bool dry_run)
{
        char *operand1 = NULL, *operand2 = NULL;
        struct filter_pred *pred;
        struct filter_pred *root;
        struct postfix_elt *elt;
        struct pred_stack stack = { }; /* init to NULL */
        int err;
        int n_preds = 0;

        n_preds = count_preds(ps);
        if (n_preds >= MAX_FILTER_PRED) {
                parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0);
                return -ENOSPC;
        }

        err = check_preds(ps);
        if (err)
                return err;

        if (!dry_run) {
                err = __alloc_pred_stack(&stack, n_preds);
                if (err)
                        return err;
                err = __alloc_preds(filter, n_preds);
                if (err)
                        goto fail;
        }

        n_preds = 0;
        list_for_each_entry(elt, &ps->postfix, list) {
                if (elt->op == OP_NONE) {
                        if (!operand1)
                                operand1 = elt->operand;
                        else if (!operand2)
                                operand2 = elt->operand;
                        else {
                                parse_error(ps, FILT_ERR_TOO_MANY_OPERANDS, 0);
                                err = -EINVAL;
                                goto fail;
                        }
                        continue;
                }

                if (elt->op == OP_NOT) {
                        if (!n_preds || operand1 || operand2) {
                                parse_error(ps, FILT_ERR_ILLEGAL_NOT_OP, 0);
                                err = -EINVAL;
                                goto fail;
                        }
                        if (!dry_run)
                                filter->preds[n_preds - 1].not ^= 1;
                        continue;
                }

                if (WARN_ON(n_preds++ == MAX_FILTER_PRED)) {
                        parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0);
                        err = -ENOSPC;
                        goto fail;
                }

                pred = create_pred(ps, call, elt->op, operand1, operand2);
                if (!pred) {
                        err = -EINVAL;
                        goto fail;
                }

                if (!dry_run) {
                        err = filter_add_pred(ps, filter, pred, &stack);
                        if (err)
                                goto fail;
                }

                operand1 = operand2 = NULL;
        }

        if (!dry_run) {
                /* We should have one item left on the stack */
                pred = __pop_pred_stack(&stack);
                if (!pred)
                        return -EINVAL;
                /* This item is where we start from in matching */
                root = pred;
                /* Make sure the stack is empty */
                pred = __pop_pred_stack(&stack);
                if (WARN_ON(pred)) {
                        err = -EINVAL;
                        filter->root = NULL;
                        goto fail;
                }
                err = check_pred_tree(filter, root);
                if (err)
                        goto fail;

                /* Optimize the tree */
                err = fold_pred_tree(filter, root);
                if (err)
                        goto fail;

                /* We don't set root until we know it works */
                barrier();
                filter->root = root;
        }

        err = 0;
fail:
        __free_pred_stack(&stack);
        return err;
}

static inline void event_set_filtered_flag(struct trace_event_file *file)
{
        struct trace_event_call *call = file->event_call;

        if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
                call->flags |= TRACE_EVENT_FL_FILTERED;
        else
                file->flags |= EVENT_FILE_FL_FILTERED;
}

static inline void event_set_filter(struct trace_event_file *file,
                                    struct event_filter *filter)
{
        struct trace_event_call *call = file->event_call;

        if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
                rcu_assign_pointer(call->filter, filter);
        else
                rcu_assign_pointer(file->filter, filter);
}

static inline void event_clear_filter(struct trace_event_file *file)
{
        struct trace_event_call *call = file->event_call;

        if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
                RCU_INIT_POINTER(call->filter, NULL);
        else
                RCU_INIT_POINTER(file->filter, NULL);
}

static inline void
event_set_no_set_filter_flag(struct trace_event_file *file)
{
        struct trace_event_call *call = file->event_call;

        if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
                call->flags |= TRACE_EVENT_FL_NO_SET_FILTER;
        else
                file->flags |= EVENT_FILE_FL_NO_SET_FILTER;
}

static inline void
event_clear_no_set_filter_flag(struct trace_event_file *file)
{
        struct trace_event_call *call = file->event_call;

        if (call->flags & TRACE_EVENT_FL_USE_CALL_FILTER)
                call->flags &= ~TRACE_EVENT_FL_NO_SET_FILTER;
        else
                file->flags &= ~EVENT_FILE_FL_NO_SET_FILTER;
}

static inline bool
event_no_set_filter_flag(struct trace_event_file *file)
{
        struct trace_event_call *call = file->event_call;

        if (file->flags & EVENT_FILE_FL_NO_SET_FILTER)
                return true;

        if ((call->flags & TRACE_EVENT_FL_USE_CALL_FILTER) &&
            (call->flags & TRACE_EVENT_FL_NO_SET_FILTER))
                return true;

        return false;
}

struct filter_list {
        struct list_head        list;
        struct event_filter     *filter;
};

static int replace_system_preds(struct trace_subsystem_dir *dir,
                                struct trace_array *tr,
                                struct filter_parse_state *ps,
                                char *filter_string)
{
        struct trace_event_file *file;
        struct filter_list *filter_item;
        struct filter_list *tmp;
        LIST_HEAD(filter_list);
        bool fail = true;
        int err;

        list_for_each_entry(file, &tr->events, list) {
                if (file->system != dir)
                        continue;

                /*
                 * Try to see if the filter can be applied
                 *  (filter arg is ignored on dry_run)
                 */
                err = replace_preds(file->event_call, NULL, ps, true);
                if (err)
                        event_set_no_set_filter_flag(file);
                else
                        event_clear_no_set_filter_flag(file);
        }

        list_for_each_entry(file, &tr->events, list) {
                struct event_filter *filter;

                if (file->system != dir)
                        continue;

                if (event_no_set_filter_flag(file))
                        continue;

                filter_item = kzalloc(sizeof(*filter_item), GFP_KERNEL);
                if (!filter_item)
                        goto fail_mem;

                list_add_tail(&filter_item->list, &filter_list);

                filter_item->filter = __alloc_filter();
                if (!filter_item->filter)
                        goto fail_mem;
                filter = filter_item->filter;

                /* Can only fail on no memory */
                err = replace_filter_string(filter, filter_string);
                if (err)
                        goto fail_mem;

                err = replace_preds(file->event_call, filter, ps, false);
                if (err) {
                        filter_disable(file);
                        parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);
                        append_filter_err(ps, filter);
                } else
                        event_set_filtered_flag(file);
                /*
                 * Regardless of if this returned an error, we still
                 * replace the filter for the call.
                 */
                filter = event_filter(file);
                event_set_filter(file, filter_item->filter);
                filter_item->filter = filter;

                fail = false;
        }

        if (fail)
                goto fail;

        /*
         * The calls can still be using the old filters.
         * Do a synchronize_sched() to ensure all calls are
         * done with them before we free them.
         */
        synchronize_sched();
        list_for_each_entry_safe(filter_item, tmp, &filter_list, list) {
                __free_filter(filter_item->filter);
                list_del(&filter_item->list);
                kfree(filter_item);
        }
        return 0;
 fail:
        /* No call succeeded */
        list_for_each_entry_safe(filter_item, tmp, &filter_list, list) {
                list_del(&filter_item->list);
                kfree(filter_item);
        }
        parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);
        return -EINVAL;
 fail_mem:
        /* If any call succeeded, we still need to sync */
        if (!fail)
                synchronize_sched();
        list_for_each_entry_safe(filter_item, tmp, &filter_list, list) {
                __free_filter(filter_item->filter);
                list_del(&filter_item->list);
                kfree(filter_item);
        }
        return -ENOMEM;
}

static int create_filter_start(char *filter_str, bool set_str,
                               struct filter_parse_state **psp,
                               struct event_filter **filterp)
{
        struct event_filter *filter;
        struct filter_parse_state *ps = NULL;
        int err = 0;

        WARN_ON_ONCE(*psp || *filterp);

        /* allocate everything, and if any fails, free all and fail */
        filter = __alloc_filter();
        if (filter && set_str)
                err = replace_filter_string(filter, filter_str);

        ps = kzalloc(sizeof(*ps), GFP_KERNEL);

        if (!filter || !ps || err) {
                kfree(ps);
                __free_filter(filter);
                return -ENOMEM;
        }

        /* we're committed to creating a new filter */
        *filterp = filter;
        *psp = ps;

        parse_init(ps, filter_ops, filter_str);
        err = filter_parse(ps);
        if (err && set_str)
                append_filter_err(ps, filter);
        return err;
}

static void create_filter_finish(struct filter_parse_state *ps)
{
        if (ps) {
                filter_opstack_clear(ps);
                postfix_clear(ps);
                kfree(ps);
        }
}

/**
 * create_filter - create a filter for a trace_event_call
 * @call: trace_event_call to create a filter for
 * @filter_str: filter string
 * @set_str: remember @filter_str and enable detailed error in filter
 * @filterp: out param for created filter (always updated on return)
 *
 * Creates a filter for @call with @filter_str.  If @set_str is %true,
 * @filter_str is copied and recorded in the new filter.
 *
 * On success, returns 0 and *@filterp points to the new filter.  On
 * failure, returns -errno and *@filterp may point to %NULL or to a new
 * filter.  In the latter case, the returned filter contains error
 * information if @set_str is %true and the caller is responsible for
 * freeing it.
 */
static int create_filter(struct trace_event_call *call,
                         char *filter_str, bool set_str,
                         struct event_filter **filterp)
{
        struct event_filter *filter = NULL;
        struct filter_parse_state *ps = NULL;
        int err;

        err = create_filter_start(filter_str, set_str, &ps, &filter);
        if (!err) {
                err = replace_preds(call, filter, ps, false);
                if (err && set_str)
                        append_filter_err(ps, filter);
        }
        create_filter_finish(ps);

        *filterp = filter;
        return err;
}

int create_event_filter(struct trace_event_call *call,
                        char *filter_str, bool set_str,
                        struct event_filter **filterp)
{
        return create_filter(call, filter_str, set_str, filterp);
}

/**
 * create_system_filter - create a filter for an event_subsystem
 * @system: event_subsystem to create a filter for
 * @filter_str: filter string
 * @filterp: out param for created filter (always updated on return)
 *
 * Identical to create_filter() except that it creates a subsystem filter
 * and always remembers @filter_str.
 */
static int create_system_filter(struct trace_subsystem_dir *dir,
                                struct trace_array *tr,
                                char *filter_str, struct event_filter **filterp)
{
        struct event_filter *filter = NULL;
        struct filter_parse_state *ps = NULL;
        int err;

        err = create_filter_start(filter_str, true, &ps, &filter);

        if (!err) {
                err = replace_system_preds(dir, tr, ps, filter_str);
                if (!err) {
                        /* System filters just show a default message */
                        kfree(filter->filter_string);
                        filter->filter_string = NULL;
                } else {
                        append_filter_err(ps, filter);
                }
        }
        create_filter_finish(ps);

        *filterp = filter;
        return err;
}

/* caller must hold event_mutex */
int apply_event_filter(struct trace_event_file *file, char *filter_string)
{
        struct trace_event_call *call = file->event_call;
        struct event_filter *filter;
        int err;

        if (!strcmp(strstrip(filter_string), "0")) {
                filter_disable(file);
                filter = event_filter(file);

                if (!filter)
                        return 0;

                event_clear_filter(file);

                /* Make sure the filter is not being used */
                synchronize_sched();
                __free_filter(filter);

                return 0;
        }

        err = create_filter(call, filter_string, true, &filter);

        /*
         * Always swap the call filter with the new filter
         * even if there was an error. If there was an error
         * in the filter, we disable the filter and show the error
         * string
         */
        if (filter) {
                struct event_filter *tmp;

                tmp = event_filter(file);
                if (!err)
                        event_set_filtered_flag(file);
                else
                        filter_disable(file);

                event_set_filter(file, filter);

                if (tmp) {
                        /* Make sure the call is done with the filter */
                        synchronize_sched();
                        __free_filter(tmp);
                }
        }

        return err;
}

int apply_subsystem_event_filter(struct trace_subsystem_dir *dir,
                                 char *filter_string)
{
        struct event_subsystem *system = dir->subsystem;
        struct trace_array *tr = dir->tr;
        struct event_filter *filter;
        int err = 0;

        mutex_lock(&event_mutex);

        /* Make sure the system still has events */
        if (!dir->nr_events) {
                err = -ENODEV;
                goto out_unlock;
        }

        if (!strcmp(strstrip(filter_string), "0")) {
                filter_free_subsystem_preds(dir, tr);
                remove_filter_string(system->filter);
                filter = system->filter;
                system->filter = NULL;
                /* Ensure all filters are no longer used */
                synchronize_sched();
                filter_free_subsystem_filters(dir, tr);
                __free_filter(filter);
                goto out_unlock;
        }

        err = create_system_filter(dir, tr, filter_string, &filter);
        if (filter) {
                /*
                 * No event actually uses the system filter
                 * we can free it without synchronize_sched().
                 */
                __free_filter(system->filter);
                system->filter = filter;
        }
out_unlock:
        mutex_unlock(&event_mutex);

        return err;
}

#ifdef CONFIG_PERF_EVENTS

void ftrace_profile_free_filter(struct perf_event *event)
{
        struct event_filter *filter = event->filter;

        event->filter = NULL;
        __free_filter(filter);
}

struct function_filter_data {
        struct ftrace_ops *ops;
        int first_filter;
        int first_notrace;
};

#ifdef CONFIG_FUNCTION_TRACER
static char **
ftrace_function_filter_re(char *buf, int len, int *count)
{
        char *str, **re;

        str = kstrndup(buf, len, GFP_KERNEL);
        if (!str)
                return NULL;

        /*
         * The argv_split function takes white space
         * as a separator, so convert ',' into spaces.
         */
        strreplace(str, ',', ' ');

        re = argv_split(GFP_KERNEL, str, count);
        kfree(str);
        return re;
}

static int ftrace_function_set_regexp(struct ftrace_ops *ops, int filter,
                                      int reset, char *re, int len)
{
        int ret;

        if (filter)
                ret = ftrace_set_filter(ops, re, len, reset);
        else
                ret = ftrace_set_notrace(ops, re, len, reset);

        return ret;
}

static int __ftrace_function_set_filter(int filter, char *buf, int len,
                                        struct function_filter_data *data)
{
        int i, re_cnt, ret = -EINVAL;
        int *reset;
        char **re;

        reset = filter ? &data->first_filter : &data->first_notrace;

        /*
         * The 'ip' field could have multiple filters set, separated
         * either by space or comma. We first cut the filter and apply
         * all pieces separatelly.
         */
        re = ftrace_function_filter_re(buf, len, &re_cnt);
        if (!re)
                return -EINVAL;

        for (i = 0; i < re_cnt; i++) {
                ret = ftrace_function_set_regexp(data->ops, filter, *reset,
                                                 re[i], strlen(re[i]));
                if (ret)
                        break;

                if (*reset)
                        *reset = 0;
        }

        argv_free(re);
        return ret;
}

static int ftrace_function_check_pred(struct filter_pred *pred, int leaf)
{
        struct ftrace_event_field *field = pred->field;

        if (leaf) {
                /*
                 * Check the leaf predicate for function trace, verify:
                 *  - only '==' and '!=' is used
                 *  - the 'ip' field is used
                 */
                if ((pred->op != OP_EQ) && (pred->op != OP_NE))
                        return -EINVAL;

                if (strcmp(field->name, "ip"))
                        return -EINVAL;
        } else {
                /*
                 * Check the non leaf predicate for function trace, verify:
                 *  - only '||' is used
                */
                if (pred->op != OP_OR)
                        return -EINVAL;
        }

        return 0;
}

static int ftrace_function_set_filter_cb(enum move_type move,
                                         struct filter_pred *pred,
                                         int *err, void *data)
{
        /* Checking the node is valid for function trace. */
        if ((move != MOVE_DOWN) ||
            (pred->left != FILTER_PRED_INVALID)) {
                *err = ftrace_function_check_pred(pred, 0);
        } else {
                *err = ftrace_function_check_pred(pred, 1);
                if (*err)
                        return WALK_PRED_ABORT;

                *err = __ftrace_function_set_filter(pred->op == OP_EQ,
                                                    pred->regex.pattern,
                                                    pred->regex.len,
                                                    data);
        }

        return (*err) ? WALK_PRED_ABORT : WALK_PRED_DEFAULT;
}

static int ftrace_function_set_filter(struct perf_event *event,
                                      struct event_filter *filter)
{
        struct function_filter_data data = {
                .first_filter  = 1,
                .first_notrace = 1,
                .ops           = &event->ftrace_ops,
        };

        return walk_pred_tree(filter->preds, filter->root,
                              ftrace_function_set_filter_cb, &data);
}
#else
static int ftrace_function_set_filter(struct perf_event *event,
                                      struct event_filter *filter)
{
        return -ENODEV;
}
#endif /* CONFIG_FUNCTION_TRACER */

int ftrace_profile_set_filter(struct perf_event *event, int event_id,
                              char *filter_str)
{
        int err;
        struct event_filter *filter;
        struct trace_event_call *call;

        mutex_lock(&event_mutex);

        call = event->tp_event;

        err = -EINVAL;
        if (!call)
                goto out_unlock;

        err = -EEXIST;
        if (event->filter)
                goto out_unlock;

        err = create_filter(call, filter_str, false, &filter);
        if (err)
                goto free_filter;

        if (ftrace_event_is_function(call))
                err = ftrace_function_set_filter(event, filter);
        else
                event->filter = filter;

free_filter:
        if (err || ftrace_event_is_function(call))
                __free_filter(filter);

out_unlock:
        mutex_unlock(&event_mutex);

        return err;
}

#endif /* CONFIG_PERF_EVENTS */

#ifdef CONFIG_FTRACE_STARTUP_TEST

#include <linux/types.h>
#include <linux/tracepoint.h>

#define CREATE_TRACE_POINTS
#include "trace_events_filter_test.h"

#define DATA_REC(m, va, vb, vc, vd, ve, vf, vg, vh, nvisit) \
{ \
        .filter = FILTER, \
        .rec    = { .a = va, .b = vb, .c = vc, .d = vd, \
                    .e = ve, .f = vf, .g = vg, .h = vh }, \
        .match  = m, \
        .not_visited = nvisit, \
}
#define YES 1
#define NO  0

static struct test_filter_data_t {
        char *filter;
        struct trace_event_raw_ftrace_test_filter rec;
        int match;
        char *not_visited;
} test_filter_data[] = {
#define FILTER "a == 1 && b == 1 && c == 1 && d == 1 && " \
               "e == 1 && f == 1 && g == 1 && h == 1"
        DATA_REC(YES, 1, 1, 1, 1, 1, 1, 1, 1, ""),
        DATA_REC(NO,  0, 1, 1, 1, 1, 1, 1, 1, "bcdefgh"),
        DATA_REC(NO,  1, 1, 1, 1, 1, 1, 1, 0, ""),
#undef FILTER
#define FILTER "a == 1 || b == 1 || c == 1 || d == 1 || " \
               "e == 1 || f == 1 || g == 1 || h == 1"
        DATA_REC(NO,  0, 0, 0, 0, 0, 0, 0, 0, ""),
        DATA_REC(YES, 0, 0, 0, 0, 0, 0, 0, 1, ""),
        DATA_REC(YES, 1, 0, 0, 0, 0, 0, 0, 0, "bcdefgh"),
#undef FILTER
#define FILTER "(a == 1 || b == 1) && (c == 1 || d == 1) && " \
               "(e == 1 || f == 1) && (g == 1 || h == 1)"
        DATA_REC(NO,  0, 0, 1, 1, 1, 1, 1, 1, "dfh"),
        DATA_REC(YES, 0, 1, 0, 1, 0, 1, 0, 1, ""),
        DATA_REC(YES, 1, 0, 1, 0, 0, 1, 0, 1, "bd"),
        DATA_REC(NO,  1, 0, 1, 0, 0, 1, 0, 0, "bd"),
#undef FILTER
#define FILTER "(a == 1 && b == 1) || (c == 1 && d == 1) || " \
               "(e == 1 && f == 1) || (g == 1 && h == 1)"
        DATA_REC(YES, 1, 0, 1, 1, 1, 1, 1, 1, "efgh"),
        DATA_REC(YES, 0, 0, 0, 0, 0, 0, 1, 1, ""),
        DATA_REC(NO,  0, 0, 0, 0, 0, 0, 0, 1, ""),
#undef FILTER
#define FILTER "(a == 1 && b == 1) && (c == 1 && d == 1) && " \
               "(e == 1 && f == 1) || (g == 1 && h == 1)"
        DATA_REC(YES, 1, 1, 1, 1, 1, 1, 0, 0, "gh"),
        DATA_REC(NO,  0, 0, 0, 0, 0, 0, 0, 1, ""),
        DATA_REC(YES, 1, 1, 1, 1, 1, 0, 1, 1, ""),
#undef FILTER
#define FILTER "((a == 1 || b == 1) || (c == 1 || d == 1) || " \
               "(e == 1 || f == 1)) && (g == 1 || h == 1)"
        DATA_REC(YES, 1, 1, 1, 1, 1, 1, 0, 1, "bcdef"),
        DATA_REC(NO,  0, 0, 0, 0, 0, 0, 0, 0, ""),
        DATA_REC(YES, 1, 1, 1, 1, 1, 0, 1, 1, "h"),
#undef FILTER
#define FILTER "((((((((a == 1) && (b == 1)) || (c == 1)) && (d == 1)) || " \
               "(e == 1)) && (f == 1)) || (g == 1)) && (h == 1))"
        DATA_REC(YES, 1, 1, 1, 1, 1, 1, 1, 1, "ceg"),
        DATA_REC(NO,  0, 1, 0, 1, 0, 1, 0, 1, ""),
        DATA_REC(NO,  1, 0, 1, 0, 1, 0, 1, 0, ""),
#undef FILTER
#define FILTER "((((((((a == 1) || (b == 1)) && (c == 1)) || (d == 1)) && " \
               "(e == 1)) || (f == 1)) && (g == 1)) || (h == 1))"
        DATA_REC(YES, 1, 1, 1, 1, 1, 1, 1, 1, "bdfh"),
        DATA_REC(YES, 0, 1, 0, 1, 0, 1, 0, 1, ""),
        DATA_REC(YES, 1, 0, 1, 0, 1, 0, 1, 0, "bdfh"),
};

#undef DATA_REC
#undef FILTER
#undef YES
#undef NO

#define DATA_CNT (sizeof(test_filter_data)/sizeof(struct test_filter_data_t))

static int test_pred_visited;

static int test_pred_visited_fn(struct filter_pred *pred, void *event)
{
        struct ftrace_event_field *field = pred->field;

        test_pred_visited = 1;
        printk(KERN_INFO "\npred visited %s\n", field->name);
        return 1;
}

static int test_walk_pred_cb(enum move_type move, struct filter_pred *pred,
                             int *err, void *data)
{
        char *fields = data;

        if ((move == MOVE_DOWN) &&
            (pred->left == FILTER_PRED_INVALID)) {
                struct ftrace_event_field *field = pred->field;

                if (!field) {
                        WARN(1, "all leafs should have field defined");
                        return WALK_PRED_DEFAULT;
                }
                if (!strchr(fields, *field->name))
                        return WALK_PRED_DEFAULT;

                WARN_ON(!pred->fn);
                pred->fn = test_pred_visited_fn;
        }
        return WALK_PRED_DEFAULT;
}

static __init int ftrace_test_event_filter(void)
{
        int i;

        printk(KERN_INFO "Testing ftrace filter: ");

        for (i = 0; i < DATA_CNT; i++) {
                struct event_filter *filter = NULL;
                struct test_filter_data_t *d = &test_filter_data[i];
                int err;

                err = create_filter(&event_ftrace_test_filter, d->filter,
                                    false, &filter);
                if (err) {
                        printk(KERN_INFO
                               "Failed to get filter for '%s', err %d\n",
                               d->filter, err);
                        __free_filter(filter);
                        break;
                }

                /*
                 * The preemption disabling is not really needed for self
                 * tests, but the rcu dereference will complain without it.
                 */
                preempt_disable();
                if (*d->not_visited)
                        walk_pred_tree(filter->preds, filter->root,
                                       test_walk_pred_cb,
                                       d->not_visited);

                test_pred_visited = 0;
                err = filter_match_preds(filter, &d->rec);
                preempt_enable();

                __free_filter(filter);

                if (test_pred_visited) {
                        printk(KERN_INFO
                               "Failed, unwanted pred visited for filter %s\n",
                               d->filter);
                        break;
                }

                if (err != d->match) {
                        printk(KERN_INFO
                               "Failed to match filter '%s', expected %d\n",
                               d->filter, d->match);
                        break;
                }
        }

        if (i == DATA_CNT)
                printk(KERN_CONT "OK\n");

        return 0;
}

late_initcall(ftrace_test_event_filter);

#endif /* CONFIG_FTRACE_STARTUP_TEST */