trace_events_filter.c

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/*
 * 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 <[email protected]>
 */

#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_NONE,
    OP_OPEN_PAREN,
};

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

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_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,
};

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",
};

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;
};

#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;                          \
    default:                            \
        break;                          \
    }                               \
                                    \
    return match;                           \
}

#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;
}

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;
}

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)
            return match;
    }
    return match;
}

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);
}

void print_event_filter(struct ftrace_event_call *call, struct trace_seq *s)
{
    struct event_filter *filter;

    mutex_lock(&event_mutex);
    filter = call->filter;
    if (filter && filter->filter_string)
        trace_seq_printf(s, "%s\n", filter->filter_string);
    else
        trace_seq_printf(s, "none\n");
    mutex_unlock(&event_mutex);
}

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_printf(s, DEFAULT_SYS_FILTER_MESSAGE "\n");
    mutex_unlock(&event_mutex);
}

static struct ftrace_event_field *
__find_event_field(struct list_head *head, char *name)
{
    struct ftrace_event_field *field;

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

    return NULL;
}

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

    field = __find_event_field(&ftrace_common_fields, name);
    if (field)
        return field;

    head = trace_get_fields(call);
    return __find_event_field(head, name);
}

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->left == FILTER_PRED_INVALID) &&
            right->index & FILTER_PRED_FOLD &&
            (right->op == dest->op ||
             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)
{
    if (filter->preds) {
        kfree(filter->preds);
        filter->preds = NULL;
    }
    filter->a_preds = 0;
    filter->n_preds = 0;
}

static void filter_disable(struct ftrace_event_call *call)
{
    call->flags &= ~TRACE_EVENT_FL_FILTERED;
}

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

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

/*
 * Called when destroying the ftrace_event_call.
 * The call is being freed, so we do not need to worry about
 * the call being currently used. This is for module code removing
 * the tracepoints from within it.
 */
void destroy_preds(struct ftrace_event_call *call)
{
    __free_filter(call->filter);
    call->filter = NULL;
}

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 void filter_free_subsystem_preds(struct event_subsystem *system)
{
    struct ftrace_event_call *call;

    list_for_each_entry(call, &ftrace_events, list) {
        if (strcmp(call->class->system, system->name) != 0)
            continue;

        filter_disable(call);
        remove_filter_string(call->filter);
    }
}

static void filter_free_subsystem_filters(struct event_subsystem *system)
{
    struct ftrace_event_call *call;

    list_for_each_entry(call, &ftrace_events, list) {
        if (strcmp(call->class->system, system->name) != 0)
            continue;
        __free_filter(call->filter);
        call->filter = NULL;
    }
}

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_function_field(struct ftrace_event_field *field)
{
    return field->filter_type == FILTER_TRACE_FN;
}

static bool is_string_field(struct ftrace_event_field *field)
{
    return field->filter_type == FILTER_DYN_STRING ||
           field->filter_type == FILTER_STATIC_STRING ||
           field->filter_type == FILTER_PTR_STRING;
}

static int 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 0;
    if (!is_string_field(field) && op == OP_GLOB)
        return 0;

    return 1;
}

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 (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 = strict_strtoll(pred->regex.pattern, 0, &val);
        else
            ret = strict_strtoull(pred->regex.pattern, 0, &val);
        if (ret) {
            parse_error(ps, FILT_ERR_ILLEGAL_INTVAL, 0);
            return -EINVAL;
        }
        pred->val = val;

        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)
{
    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)
{
    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 ftrace_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 = 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;

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

        if (elt->op == OP_AND || elt->op == OP_OR) {
            n_logical_preds++;
            continue;
        }
        n_normal_preds++;
    }

    if (!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 ftrace_event_call *call,
             struct event_filter *filter,
             struct filter_parse_state *ps,
             char *filter_string,
             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 (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;
}

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

static int replace_system_preds(struct event_subsystem *system,
                struct filter_parse_state *ps,
                char *filter_string)
{
    struct ftrace_event_call *call;
    struct filter_list *filter_item;
    struct filter_list *tmp;
    LIST_HEAD(filter_list);
    bool fail = true;
    int err;

    list_for_each_entry(call, &ftrace_events, list) {

        if (strcmp(call->class->system, system->name) != 0)
            continue;

        /*
         * Try to see if the filter can be applied
         *  (filter arg is ignored on dry_run)
         */
        err = replace_preds(call, NULL, ps, filter_string, true);
        if (err)
            call->flags |= TRACE_EVENT_FL_NO_SET_FILTER;
        else
            call->flags &= ~TRACE_EVENT_FL_NO_SET_FILTER;
    }

    list_for_each_entry(call, &ftrace_events, list) {
        struct event_filter *filter;

        if (strcmp(call->class->system, system->name) != 0)
            continue;

        if (call->flags & TRACE_EVENT_FL_NO_SET_FILTER)
            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(call, filter, ps, filter_string, false);
        if (err) {
            filter_disable(call);
            parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);
            append_filter_err(ps, filter);
        } else
            call->flags |= TRACE_EVENT_FL_FILTERED;
        /*
         * Regardless of if this returned an error, we still
         * replace the filter for the call.
         */
        filter = call->filter;
        rcu_assign_pointer(call->filter, 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);
    }
}

static int create_filter(struct ftrace_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, filter_str, false);
        if (err && set_str)
            append_filter_err(ps, filter);
    }
    create_filter_finish(ps);

    *filterp = filter;
    return err;
}

static int create_system_filter(struct event_subsystem *system,
                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(system, 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;
}

int apply_event_filter(struct ftrace_event_call *call, char *filter_string)
{
    struct event_filter *filter;
    int err = 0;

    mutex_lock(&event_mutex);

    if (!strcmp(strstrip(filter_string), "0")) {
        filter_disable(call);
        filter = call->filter;
        if (!filter)
            goto out_unlock;
        RCU_INIT_POINTER(call->filter, NULL);
        /* Make sure the filter is not being used */
        synchronize_sched();
        __free_filter(filter);
        goto out_unlock;
    }

    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 = call->filter;

        if (!err)
            call->flags |= TRACE_EVENT_FL_FILTERED;
        else
            filter_disable(call);

        rcu_assign_pointer(call->filter, filter);

        if (tmp) {
            /* Make sure the call is done with the filter */
            synchronize_sched();
            __free_filter(tmp);
        }
    }
out_unlock:
    mutex_unlock(&event_mutex);

    return err;
}

int apply_subsystem_event_filter(struct event_subsystem *system,
                 char *filter_string)
{
    struct event_filter *filter;
    int err = 0;

    mutex_lock(&event_mutex);

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

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

    err = create_system_filter(system, 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, *sep, **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.
     */
    while ((sep = strchr(str, ',')))
        *sep = ' ';

    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 ftrace_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 ftrace_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 */