Merge tag 'configfs-5.11' of git://git.infradead.org/users/hch/configfs

[mirror_ubuntu-hirsute-kernel.git] / kernel / trace / trace_events_filter.c

// SPDX-License-Identifier: GPL-2.0
/*
 * trace_events_filter - generic event filtering
 *
 * 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"

/* Due to token parsing '<=' must be before '<' and '>=' must be before '>' */
#define OPS                                     \
        C( OP_GLOB,     "~"  ),                 \
        C( OP_NE,       "!=" ),                 \
        C( OP_EQ,       "==" ),                 \
        C( OP_LE,       "<=" ),                 \
        C( OP_LT,       "<"  ),                 \
        C( OP_GE,       ">=" ),                 \
        C( OP_GT,       ">"  ),                 \
        C( OP_BAND,     "&"  ),                 \
        C( OP_MAX,      NULL )

#undef C
#define C(a, b) a

enum filter_op_ids { OPS };

#undef C
#define C(a, b) b

static const char * ops[] = { OPS };

/*
 * pred functions are OP_LE, OP_LT, OP_GE, OP_GT, and OP_BAND
 * pred_funcs_##type below must match the order of them above.
 */
#define PRED_FUNC_START                 OP_LE
#define PRED_FUNC_MAX                   (OP_BAND - PRED_FUNC_START)

#define ERRORS                                                          \
        C(NONE,                 "No error"),                            \
        C(INVALID_OP,           "Invalid operator"),                    \
        C(TOO_MANY_OPEN,        "Too many '('"),                        \
        C(TOO_MANY_CLOSE,       "Too few '('"),                         \
        C(MISSING_QUOTE,        "Missing matching quote"),              \
        C(OPERAND_TOO_LONG,     "Operand too long"),                    \
        C(EXPECT_STRING,        "Expecting string field"),              \
        C(EXPECT_DIGIT,         "Expecting numeric field"),             \
        C(ILLEGAL_FIELD_OP,     "Illegal operation for field type"),    \
        C(FIELD_NOT_FOUND,      "Field not found"),                     \
        C(ILLEGAL_INTVAL,       "Illegal integer value"),               \
        C(BAD_SUBSYS_FILTER,    "Couldn't find or set field in one of a subsystem's events"), \
        C(TOO_MANY_PREDS,       "Too many terms in predicate expression"), \
        C(INVALID_FILTER,       "Meaningless filter expression"),       \
        C(IP_FIELD_ONLY,        "Only 'ip' field is supported for function trace"), \
        C(INVALID_VALUE,        "Invalid value (did you forget quotes)?"), \
        C(ERRNO,                "Error"),                               \
        C(NO_FILTER,            "No filter found")

#undef C
#define C(a, b)         FILT_ERR_##a

enum { ERRORS };

#undef C
#define C(a, b)         b

static const char *err_text[] = { ERRORS };

/* Called after a '!' character but "!=" and "!~" are not "not"s */
static bool is_not(const char *str)
{
        switch (str[1]) {
        case '=':
        case '~':
                return false;
        }
        return true;
}

/**
 * prog_entry - a singe entry in the filter program
 * @target:          Index to jump to on a branch (actually one minus the index)
 * @when_to_branch:  The value of the result of the predicate to do a branch
 * @pred:            The predicate to execute.
 */
struct prog_entry {
        int                     target;
        int                     when_to_branch;
        struct filter_pred      *pred;
};

/**
 * update_preds- assign a program entry a label target
 * @prog: The program array
 * @N: The index of the current entry in @prog
 * @when_to_branch: What to assign a program entry for its branch condition
 *
 * The program entry at @N has a target that points to the index of a program
 * entry that can have its target and when_to_branch fields updated.
 * Update the current program entry denoted by index @N target field to be
 * that of the updated entry. This will denote the entry to update if
 * we are processing an "||" after an "&&"
 */
static void update_preds(struct prog_entry *prog, int N, int invert)
{
        int t, s;

        t = prog[N].target;
        s = prog[t].target;
        prog[t].when_to_branch = invert;
        prog[t].target = N;
        prog[N].target = s;
}

struct filter_parse_error {
        int lasterr;
        int lasterr_pos;
};

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

typedef int (*parse_pred_fn)(const char *str, void *data, int pos,
                             struct filter_parse_error *pe,
                             struct filter_pred **pred);

enum {
        INVERT          = 1,
        PROCESS_AND     = 2,
        PROCESS_OR      = 4,
};

/*
 * Without going into a formal proof, this explains the method that is used in
 * parsing the logical expressions.
 *
 * For example, if we have: "a && !(!b || (c && g)) || d || e && !f"
 * The first pass will convert it into the following program:
 *
 * n1: r=a;       l1: if (!r) goto l4;
 * n2: r=b;       l2: if (!r) goto l4;
 * n3: r=c; r=!r; l3: if (r) goto l4;
 * n4: r=g; r=!r; l4: if (r) goto l5;
 * n5: r=d;       l5: if (r) goto T
 * n6: r=e;       l6: if (!r) goto l7;
 * n7: r=f; r=!r; l7: if (!r) goto F
 * T: return TRUE
 * F: return FALSE
 *
 * To do this, we use a data structure to represent each of the above
 * predicate and conditions that has:
 *
 *  predicate, when_to_branch, invert, target
 *
 * The "predicate" will hold the function to determine the result "r".
 * The "when_to_branch" denotes what "r" should be if a branch is to be taken
 * "&&" would contain "!r" or (0) and "||" would contain "r" or (1).
 * The "invert" holds whether the value should be reversed before testing.
 * The "target" contains the label "l#" to jump to.
 *
 * A stack is created to hold values when parentheses are used.
 *
 * To simplify the logic, the labels will start at 0 and not 1.
 *
 * The possible invert values are 1 and 0. The number of "!"s that are in scope
 * before the predicate determines the invert value, if the number is odd then
 * the invert value is 1 and 0 otherwise. This means the invert value only
 * needs to be toggled when a new "!" is introduced compared to what is stored
 * on the stack, where parentheses were used.
 *
 * The top of the stack and "invert" are initialized to zero.
 *
 * ** FIRST PASS **
 *
 * #1 A loop through all the tokens is done:
 *
 * #2 If the token is an "(", the stack is push, and the current stack value
 *    gets the current invert value, and the loop continues to the next token.
 *    The top of the stack saves the "invert" value to keep track of what
 *    the current inversion is. As "!(a && !b || c)" would require all
 *    predicates being affected separately by the "!" before the parentheses.
 *    And that would end up being equivalent to "(!a || b) && !c"
 *
 * #3 If the token is an "!", the current "invert" value gets inverted, and
 *    the loop continues. Note, if the next token is a predicate, then
 *    this "invert" value is only valid for the current program entry,
 *    and does not affect other predicates later on.
 *
 * The only other acceptable token is the predicate string.
 *
 * #4 A new entry into the program is added saving: the predicate and the
 *    current value of "invert". The target is currently assigned to the
 *    previous program index (this will not be its final value).
 *
 * #5 We now enter another loop and look at the next token. The only valid
 *    tokens are ")", "&&", "||" or end of the input string "\0".
 *
 * #6 The invert variable is reset to the current value saved on the top of
 *    the stack.
 *
 * #7 The top of the stack holds not only the current invert value, but also
 *    if a "&&" or "||" needs to be processed. Note, the "&&" takes higher
 *    precedence than "||". That is "a && b || c && d" is equivalent to
 *    "(a && b) || (c && d)". Thus the first thing to do is to see if "&&" needs
 *    to be processed. This is the case if an "&&" was the last token. If it was
 *    then we call update_preds(). This takes the program, the current index in
 *    the program, and the current value of "invert".  More will be described
 *    below about this function.
 *
 * #8 If the next token is "&&" then we set a flag in the top of the stack
 *    that denotes that "&&" needs to be processed, break out of this loop
 *    and continue with the outer loop.
 *
 * #9 Otherwise, if a "||" needs to be processed then update_preds() is called.
 *    This is called with the program, the current index in the program, but
 *    this time with an inverted value of "invert" (that is !invert). This is
 *    because the value taken will become the "when_to_branch" value of the
 *    program.
 *    Note, this is called when the next token is not an "&&". As stated before,
 *    "&&" takes higher precedence, and "||" should not be processed yet if the
 *    next logical operation is "&&".
 *
 * #10 If the next token is "||" then we set a flag in the top of the stack
 *     that denotes that "||" needs to be processed, break out of this loop
 *     and continue with the outer loop.
 *
 * #11 If this is the end of the input string "\0" then we break out of both
 *     loops.
 *
 * #12 Otherwise, the next token is ")", where we pop the stack and continue
 *     this inner loop.
 *
 * Now to discuss the update_pred() function, as that is key to the setting up
 * of the program. Remember the "target" of the program is initialized to the
 * previous index and not the "l" label. The target holds the index into the
 * program that gets affected by the operand. Thus if we have something like
 *  "a || b && c", when we process "a" the target will be "-1" (undefined).
 * When we process "b", its target is "0", which is the index of "a", as that's
 * the predicate that is affected by "||". But because the next token after "b"
 * is "&&" we don't call update_preds(). Instead continue to "c". As the
 * next token after "c" is not "&&" but the end of input, we first process the
 * "&&" by calling update_preds() for the "&&" then we process the "||" by
 * callin updates_preds() with the values for processing "||".
 *
 * What does that mean? What update_preds() does is to first save the "target"
 * of the program entry indexed by the current program entry's "target"
 * (remember the "target" is initialized to previous program entry), and then
 * sets that "target" to the current index which represents the label "l#".
 * That entry's "when_to_branch" is set to the value passed in (the "invert"
 * or "!invert"). Then it sets the current program entry's target to the saved
 * "target" value (the old value of the program that had its "target" updated
 * to the label).
 *
 * Looking back at "a || b && c", we have the following steps:
 *  "a"  - prog[0] = { "a", X, -1 } // pred, when_to_branch, target
 *  "||" - flag that we need to process "||"; continue outer loop
 *  "b"  - prog[1] = { "b", X, 0 }
 *  "&&" - flag that we need to process "&&"; continue outer loop
 * (Notice we did not process "||")
 *  "c"  - prog[2] = { "c", X, 1 }
 *  update_preds(prog, 2, 0); // invert = 0 as we are processing "&&"
 *    t = prog[2].target; // t = 1
 *    s = prog[t].target; // s = 0
 *    prog[t].target = 2; // Set target to "l2"
 *    prog[t].when_to_branch = 0;
 *    prog[2].target = s;
 * update_preds(prog, 2, 1); // invert = 1 as we are now processing "||"
 *    t = prog[2].target; // t = 0
 *    s = prog[t].target; // s = -1
 *    prog[t].target = 2; // Set target to "l2"
 *    prog[t].when_to_branch = 1;
 *    prog[2].target = s;
 *
 * #13 Which brings us to the final step of the first pass, which is to set
 *     the last program entry's when_to_branch and target, which will be
 *     when_to_branch = 0; target = N; ( the label after the program entry after
 *     the last program entry processed above).
 *
 * If we denote "TRUE" to be the entry after the last program entry processed,
 * and "FALSE" the program entry after that, we are now done with the first
 * pass.
 *
 * Making the above "a || b && c" have a progam of:
 *  prog[0] = { "a", 1, 2 }
 *  prog[1] = { "b", 0, 2 }
 *  prog[2] = { "c", 0, 3 }
 *
 * Which translates into:
 * n0: r = a; l0: if (r) goto l2;
 * n1: r = b; l1: if (!r) goto l2;
 * n2: r = c; l2: if (!r) goto l3;  // Which is the same as "goto F;"
 * T: return TRUE; l3:
 * F: return FALSE
 *
 * Although, after the first pass, the program is correct, it is
 * inefficient. The simple sample of "a || b && c" could be easily been
 * converted into:
 * n0: r = a; if (r) goto T
 * n1: r = b; if (!r) goto F
 * n2: r = c; if (!r) goto F
 * T: return TRUE;
 * F: return FALSE;
 *
 * The First Pass is over the input string. The next too passes are over
 * the program itself.
 *
 * ** SECOND PASS **
 *
 * Which brings us to the second pass. If a jump to a label has the
 * same condition as that label, it can instead jump to its target.
 * The original example of "a && !(!b || (c && g)) || d || e && !f"
 * where the first pass gives us:
 *
 * n1: r=a;       l1: if (!r) goto l4;
 * n2: r=b;       l2: if (!r) goto l4;
 * n3: r=c; r=!r; l3: if (r) goto l4;
 * n4: r=g; r=!r; l4: if (r) goto l5;
 * n5: r=d;       l5: if (r) goto T
 * n6: r=e;       l6: if (!r) goto l7;
 * n7: r=f; r=!r; l7: if (!r) goto F:
 * T: return TRUE;
 * F: return FALSE
 *
 * We can see that "l3: if (r) goto l4;" and at l4, we have "if (r) goto l5;".
 * And "l5: if (r) goto T", we could optimize this by converting l3 and l4
 * to go directly to T. To accomplish this, we start from the last
 * entry in the program and work our way back. If the target of the entry
 * has the same "when_to_branch" then we could use that entry's target.
 * Doing this, the above would end up as:
 *
 * n1: r=a;       l1: if (!r) goto l4;
 * n2: r=b;       l2: if (!r) goto l4;
 * n3: r=c; r=!r; l3: if (r) goto T;
 * n4: r=g; r=!r; l4: if (r) goto T;
 * n5: r=d;       l5: if (r) goto T;
 * n6: r=e;       l6: if (!r) goto F;
 * n7: r=f; r=!r; l7: if (!r) goto F;
 * T: return TRUE
 * F: return FALSE
 *
 * In that same pass, if the "when_to_branch" doesn't match, we can simply
 * go to the program entry after the label. That is, "l2: if (!r) goto l4;"
 * where "l4: if (r) goto T;", then we can convert l2 to be:
 * "l2: if (!r) goto n5;".
 *
 * This will have the second pass give us:
 * n1: r=a;       l1: if (!r) goto n5;
 * n2: r=b;       l2: if (!r) goto n5;
 * n3: r=c; r=!r; l3: if (r) goto T;
 * n4: r=g; r=!r; l4: if (r) goto T;
 * n5: r=d;       l5: if (r) goto T
 * n6: r=e;       l6: if (!r) goto F;
 * n7: r=f; r=!r; l7: if (!r) goto F
 * T: return TRUE
 * F: return FALSE
 *
 * Notice, all the "l#" labels are no longer used, and they can now
 * be discarded.
 *
 * ** THIRD PASS **
 *
 * For the third pass we deal with the inverts. As they simply just
 * make the "when_to_branch" get inverted, a simple loop over the
 * program to that does: "when_to_branch ^= invert;" will do the
 * job, leaving us with:
 * n1: r=a; if (!r) goto n5;
 * n2: r=b; if (!r) goto n5;
 * n3: r=c: if (!r) goto T;
 * n4: r=g; if (!r) goto T;
 * n5: r=d; if (r) goto T
 * n6: r=e; if (!r) goto F;
 * n7: r=f; if (r) goto F
 * T: return TRUE
 * F: return FALSE
 *
 * As "r = a; if (!r) goto n5;" is obviously the same as
 * "if (!a) goto n5;" without doing anything we can interperate the
 * program as:
 * n1: if (!a) goto n5;
 * n2: if (!b) goto n5;
 * n3: if (!c) goto T;
 * n4: if (!g) goto T;
 * n5: if (d) goto T
 * n6: if (!e) goto F;
 * n7: if (f) goto F
 * T: return TRUE
 * F: return FALSE
 *
 * Since the inverts are discarded at the end, there's no reason to store
 * them in the program array (and waste memory). A separate array to hold
 * the inverts is used and freed at the end.
 */
static struct prog_entry *
predicate_parse(const char *str, int nr_parens, int nr_preds,
                parse_pred_fn parse_pred, void *data,
                struct filter_parse_error *pe)
{
        struct prog_entry *prog_stack;
        struct prog_entry *prog;
        const char *ptr = str;
        char *inverts = NULL;
        int *op_stack;
        int *top;
        int invert = 0;
        int ret = -ENOMEM;
        int len;
        int N = 0;
        int i;

        nr_preds += 2; /* For TRUE and FALSE */

        op_stack = kmalloc_array(nr_parens, sizeof(*op_stack), GFP_KERNEL);
        if (!op_stack)
                return ERR_PTR(-ENOMEM);
        prog_stack = kcalloc(nr_preds, sizeof(*prog_stack), GFP_KERNEL);
        if (!prog_stack) {
                parse_error(pe, -ENOMEM, 0);
                goto out_free;
        }
        inverts = kmalloc_array(nr_preds, sizeof(*inverts), GFP_KERNEL);
        if (!inverts) {
                parse_error(pe, -ENOMEM, 0);
                goto out_free;
        }

        top = op_stack;
        prog = prog_stack;
        *top = 0;

        /* First pass */
        while (*ptr) {                                          /* #1 */
                const char *next = ptr++;

                if (isspace(*next))
                        continue;

                switch (*next) {
                case '(':                                       /* #2 */
                        if (top - op_stack > nr_parens) {
                                ret = -EINVAL;
                                goto out_free;
                        }
                        *(++top) = invert;
                        continue;
                case '!':                                       /* #3 */
                        if (!is_not(next))
                                break;
                        invert = !invert;
                        continue;
                }

                if (N >= nr_preds) {
                        parse_error(pe, FILT_ERR_TOO_MANY_PREDS, next - str);
                        goto out_free;
                }

                inverts[N] = invert;                            /* #4 */
                prog[N].target = N-1;

                len = parse_pred(next, data, ptr - str, pe, &prog[N].pred);
                if (len < 0) {
                        ret = len;
                        goto out_free;
                }
                ptr = next + len;

                N++;

                ret = -1;
                while (1) {                                     /* #5 */
                        next = ptr++;
                        if (isspace(*next))
                                continue;

                        switch (*next) {
                        case ')':
                        case '\0':
                                break;
                        case '&':
                        case '|':
                                /* accepting only "&&" or "||" */
                                if (next[1] == next[0]) {
                                        ptr++;
                                        break;
                                }
                                fallthrough;
                        default:
                                parse_error(pe, FILT_ERR_TOO_MANY_PREDS,
                                            next - str);
                                goto out_free;
                        }

                        invert = *top & INVERT;

                        if (*top & PROCESS_AND) {               /* #7 */
                                update_preds(prog, N - 1, invert);
                                *top &= ~PROCESS_AND;
                        }
                        if (*next == '&') {                     /* #8 */
                                *top |= PROCESS_AND;
                                break;
                        }
                        if (*top & PROCESS_OR) {                /* #9 */
                                update_preds(prog, N - 1, !invert);
                                *top &= ~PROCESS_OR;
                        }
                        if (*next == '|') {                     /* #10 */
                                *top |= PROCESS_OR;
                                break;
                        }
                        if (!*next)                             /* #11 */
                                goto out;

                        if (top == op_stack) {
                                ret = -1;
                                /* Too few '(' */
                                parse_error(pe, FILT_ERR_TOO_MANY_CLOSE, ptr - str);
                                goto out_free;
                        }
                        top--;                                  /* #12 */
                }
        }
 out:
        if (top != op_stack) {
                /* Too many '(' */
                parse_error(pe, FILT_ERR_TOO_MANY_OPEN, ptr - str);
                goto out_free;
        }

        if (!N) {
                /* No program? */
                ret = -EINVAL;
                parse_error(pe, FILT_ERR_NO_FILTER, ptr - str);
                goto out_free;
        }

        prog[N].pred = NULL;                                    /* #13 */
        prog[N].target = 1;             /* TRUE */
        prog[N+1].pred = NULL;
        prog[N+1].target = 0;           /* FALSE */
        prog[N-1].target = N;
        prog[N-1].when_to_branch = false;

        /* Second Pass */
        for (i = N-1 ; i--; ) {
                int target = prog[i].target;
                if (prog[i].when_to_branch == prog[target].when_to_branch)
                        prog[i].target = prog[target].target;
        }

        /* Third Pass */
        for (i = 0; i < N; i++) {
                invert = inverts[i] ^ prog[i].when_to_branch;
                prog[i].when_to_branch = invert;
                /* Make sure the program always moves forward */
                if (WARN_ON(prog[i].target <= i)) {
                        ret = -EINVAL;
                        goto out_free;
                }
        }

        kfree(op_stack);
        kfree(inverts);
        return prog;
out_free:
        kfree(op_stack);
        kfree(inverts);
        if (prog_stack) {
                for (i = 0; prog_stack[i].pred; i++)
                        kfree(prog_stack[i].pred);
                kfree(prog_stack);
        }
        return ERR_PTR(ret);
}

#define DEFINE_COMPARISON_PRED(type)                                    \
static int filter_pred_LT_##type(struct filter_pred *pred, void *event) \
{                                                                       \
        type *addr = (type *)(event + pred->offset);                    \
        type val = (type)pred->val;                                     \
        return *addr < val;                                             \
}                                                                       \
static int filter_pred_LE_##type(struct filter_pred *pred, void *event) \
{                                                                       \
        type *addr = (type *)(event + pred->offset);                    \
        type val = (type)pred->val;                                     \
        return *addr <= val;                                            \
}                                                                       \
static int filter_pred_GT_##type(struct filter_pred *pred, void *event) \
{                                                                       \
        type *addr = (type *)(event + pred->offset);                    \
        type val = (type)pred->val;                                     \
        return *addr > val;                                     \
}                                                                       \
static int filter_pred_GE_##type(struct filter_pred *pred, void *event) \
{                                                                       \
        type *addr = (type *)(event + pred->offset);                    \
        type val = (type)pred->val;                                     \
        return *addr >= val;                                            \
}                                                                       \
static int filter_pred_BAND_##type(struct filter_pred *pred, void *event) \
{                                                                       \
        type *addr = (type *)(event + pred->offset);                    \
        type val = (type)pred->val;                                     \
        return !!(*addr & val);                                         \
}                                                                       \
static const filter_pred_fn_t pred_funcs_##type[] = {                   \
        filter_pred_LE_##type,                                          \
        filter_pred_LT_##type,                                          \
        filter_pred_GE_##type,                                          \
        filter_pred_GT_##type,                                          \
        filter_pred_BAND_##type,                                        \
};

#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;

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

        switch (pred->op) {
        case OP_EQ:
                return cpu == cmp;
        case OP_NE:
                return cpu != cmp;
        case OP_LT:
                return cpu < cmp;
        case OP_LE:
                return cpu <= cmp;
        case OP_GT:
                return cpu > cmp;
        case OP_GE:
                return cpu >= cmp;
        default:
                return 0;
        }
}

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

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

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, unless @len is zero.
 */

static int regex_match_full(char *str, struct regex *r, int len)
{
        /* len of zero means str is dynamic and ends with '\0' */
        if (!len)
                return strcmp(str, r->pattern) == 0;

        return strncmp(str, r->pattern, len) == 0;
}

static int regex_match_front(char *str, struct regex *r, int len)
{
        if (len && len < r->len)
                return 0;

        return strncmp(str, r->pattern, r->len) == 0;
}

static int regex_match_middle(char *str, struct regex *r, int len)
{
        if (!len)
                return strstr(str, r->pattern) != NULL;

        return strnstr(str, r->pattern, len) != NULL;
}

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;
}

static int regex_match_glob(char *str, struct regex *r, int len __maybe_unused)
{
        if (glob_match(r->pattern, str))
                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;

        if (isdigit(buff[0]))
                return MATCH_INDEX;

        for (i = 0; i < len; i++) {
                if (buff[i] == '*') {
                        if (!i) {
                                type = MATCH_END_ONLY;
                        } else if (i == len - 1) {
                                if (type == MATCH_END_ONLY)
                                        type = MATCH_MIDDLE_ONLY;
                                else
                                        type = MATCH_FRONT_ONLY;
                                buff[i] = 0;
                                break;
                        } else {        /* pattern continues, use full glob */
                                return MATCH_GLOB;
                        }
                } else if (strchr("[?\\", buff[i])) {
                        return MATCH_GLOB;
                }
        }
        if (buff[0] == '*')
                *search = buff + 1;

        return type;
}

static void filter_build_regex(struct filter_pred *pred)
{
        struct regex *r = &pred->regex;
        char *search;
        enum regex_type type = MATCH_FULL;

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

        switch (type) {
        /* MATCH_INDEX should not happen, but if it does, match full */
        case MATCH_INDEX:
        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;
        case MATCH_GLOB:
                r->match = regex_match_glob;
                break;
        }
}

/* return 1 if event matches, 0 otherwise (discard) */
int filter_match_preds(struct event_filter *filter, void *rec)
{
        struct prog_entry *prog;
        int i;

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

        /* Protected by either SRCU(tracepoint_srcu) or preempt_disable */
        prog = rcu_dereference_raw(filter->prog);
        if (!prog)
                return 1;

        for (i = 0; prog[i].pred; i++) {
                struct filter_pred *pred = prog[i].pred;
                int match = pred->fn(pred, rec);
                if (match == prog[i].when_to_branch)
                        i = prog[i].target;
        }
        return prog[i].target;
}
EXPORT_SYMBOL_GPL(filter_match_preds);

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

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

static void append_filter_err(struct trace_array *tr,
                              struct filter_parse_error *pe,
                              struct event_filter *filter)
{
        struct trace_seq *s;
        int pos = pe->lasterr_pos;
        char *buf;
        int len;

        if (WARN_ON(!filter->filter_string))
                return;

        s = kmalloc(sizeof(*s), GFP_KERNEL);
        if (!s)
                return;
        trace_seq_init(s);

        len = strlen(filter->filter_string);
        if (pos > len)
                pos = len;

        /* indexing is off by one */
        if (pos)
                pos++;

        trace_seq_puts(s, filter->filter_string);
        if (pe->lasterr > 0) {
                trace_seq_printf(s, "\n%*s", pos, "^");
                trace_seq_printf(s, "\nparse_error: %s\n", err_text[pe->lasterr]);
                tracing_log_err(tr, "event filter parse error",
                                filter->filter_string, err_text,
                                pe->lasterr, pe->lasterr_pos);
        } else {
                trace_seq_printf(s, "\nError: (%d)\n", pe->lasterr);
                tracing_log_err(tr, "event filter parse error",
                                filter->filter_string, err_text,
                                FILT_ERR_ERRNO, 0);
        }
        trace_seq_putc(s, 0);
        buf = kmemdup_nul(s->buffer, s->seq.len, GFP_KERNEL);
        if (buf) {
                kfree(filter->filter_string);
                filter->filter_string = buf;
        }
        kfree(s);
}

static inline struct event_filter *event_filter(struct trace_event_file *file)
{
        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 void free_prog(struct event_filter *filter)
{
        struct prog_entry *prog;
        int i;

        prog = rcu_access_pointer(filter->prog);
        if (!prog)
                return;

        for (i = 0; prog[i].pred; i++)
                kfree(prog[i].pred);
        kfree(prog);
}

static void filter_disable(struct trace_event_file *file)
{
        unsigned long old_flags = file->flags;

        file->flags &= ~EVENT_FILE_FL_FILTERED;

        if (old_flags != file->flags)
                trace_buffered_event_disable();
}

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

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

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

static inline void __remove_filter(struct trace_event_file *file)
{
        filter_disable(file);
        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)
{
        __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);
        }
}

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;

        if (strcmp(type, "char *") == 0 || strcmp(type, "const char *") == 0)
                return FILTER_PTR_STRING;

        return FILTER_OTHER;
}

static filter_pred_fn_t select_comparison_fn(enum filter_op_ids op,
                                            int field_size, int field_is_signed)
{
        filter_pred_fn_t fn = NULL;
        int pred_func_index = -1;

        switch (op) {
        case OP_EQ:
        case OP_NE:
                break;
        default:
                if (WARN_ON_ONCE(op < PRED_FUNC_START))
                        return NULL;
                pred_func_index = op - PRED_FUNC_START;
                if (WARN_ON_ONCE(pred_func_index > PRED_FUNC_MAX))
                        return NULL;
        }

        switch (field_size) {
        case 8:
                if (pred_func_index < 0)
                        fn = filter_pred_64;
                else if (field_is_signed)
                        fn = pred_funcs_s64[pred_func_index];
                else
                        fn = pred_funcs_u64[pred_func_index];
                break;
        case 4:
                if (pred_func_index < 0)
                        fn = filter_pred_32;
                else if (field_is_signed)
                        fn = pred_funcs_s32[pred_func_index];
                else
                        fn = pred_funcs_u32[pred_func_index];
                break;
        case 2:
                if (pred_func_index < 0)
                        fn = filter_pred_16;
                else if (field_is_signed)
                        fn = pred_funcs_s16[pred_func_index];
                else
                        fn = pred_funcs_u16[pred_func_index];
                break;
        case 1:
                if (pred_func_index < 0)
                        fn = filter_pred_8;
                else if (field_is_signed)
                        fn = pred_funcs_s8[pred_func_index];
                else
                        fn = pred_funcs_u8[pred_func_index];
                break;
        }

        return fn;
}

/* Called when a predicate is encountered by predicate_parse() */
static int parse_pred(const char *str, void *data,
                      int pos, struct filter_parse_error *pe,
                      struct filter_pred **pred_ptr)
{
        struct trace_event_call *call = data;
        struct ftrace_event_field *field;
        struct filter_pred *pred = NULL;
        char num_buf[24];       /* Big enough to hold an address */
        char *field_name;
        char q;
        u64 val;
        int len;
        int ret;
        int op;
        int s;
        int i = 0;

        /* First find the field to associate to */
        while (isspace(str[i]))
                i++;
        s = i;

        while (isalnum(str[i]) || str[i] == '_')
                i++;

        len = i - s;

        if (!len)
                return -1;

        field_name = kmemdup_nul(str + s, len, GFP_KERNEL);
        if (!field_name)
                return -ENOMEM;

        /* Make sure that the field exists */

        field = trace_find_event_field(call, field_name);
        kfree(field_name);
        if (!field) {
                parse_error(pe, FILT_ERR_FIELD_NOT_FOUND, pos + i);
                return -EINVAL;
        }

        while (isspace(str[i]))
                i++;

        /* Make sure this op is supported */
        for (op = 0; ops[op]; op++) {
                /* This is why '<=' must come before '<' in ops[] */
                if (strncmp(str + i, ops[op], strlen(ops[op])) == 0)
                        break;
        }

        if (!ops[op]) {
                parse_error(pe, FILT_ERR_INVALID_OP, pos + i);
                goto err_free;
        }

        i += strlen(ops[op]);

        while (isspace(str[i]))
                i++;

        s = i;

        pred = kzalloc(sizeof(*pred), GFP_KERNEL);
        if (!pred)
                return -ENOMEM;

        pred->field = field;
        pred->offset = field->offset;
        pred->op = op;

        if (ftrace_event_is_function(call)) {
                /*
                 * Perf does things different with function events.
                 * It only allows an "ip" field, and expects a string.
                 * But the string does not need to be surrounded by quotes.
                 * If it is a string, the assigned function as a nop,
                 * (perf doesn't use it) and grab everything.
                 */
                if (strcmp(field->name, "ip") != 0) {
                        parse_error(pe, FILT_ERR_IP_FIELD_ONLY, pos + i);
                        goto err_free;
                }
                pred->fn = filter_pred_none;

                /*
                 * Quotes are not required, but if they exist then we need
                 * to read them till we hit a matching one.
                 */
                if (str[i] == '\'' || str[i] == '"')
                        q = str[i];
                else
                        q = 0;

                for (i++; str[i]; i++) {
                        if (q && str[i] == q)
                                break;
                        if (!q && (str[i] == ')' || str[i] == '&' ||
                                   str[i] == '|'))
                                break;
                }
                /* Skip quotes */
                if (q)
                        s++;
                len = i - s;
                if (len >= MAX_FILTER_STR_VAL) {
                        parse_error(pe, FILT_ERR_OPERAND_TOO_LONG, pos + i);
                        goto err_free;
                }

                pred->regex.len = len;
                strncpy(pred->regex.pattern, str + s, len);
                pred->regex.pattern[len] = 0;

        /* This is either a string, or an integer */
        } else if (str[i] == '\'' || str[i] == '"') {
                char q = str[i];

                /* Make sure the op is OK for strings */
                switch (op) {
                case OP_NE:
                        pred->not = 1;
                        fallthrough;
                case OP_GLOB:
                case OP_EQ:
                        break;
                default:
                        parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i);
                        goto err_free;
                }

                /* Make sure the field is OK for strings */
                if (!is_string_field(field)) {
                        parse_error(pe, FILT_ERR_EXPECT_DIGIT, pos + i);
                        goto err_free;
                }

                for (i++; str[i]; i++) {
                        if (str[i] == q)
                                break;
                }
                if (!str[i]) {
                        parse_error(pe, FILT_ERR_MISSING_QUOTE, pos + i);
                        goto err_free;
                }

                /* Skip quotes */
                s++;
                len = i - s;
                if (len >= MAX_FILTER_STR_VAL) {
                        parse_error(pe, FILT_ERR_OPERAND_TOO_LONG, pos + i);
                        goto err_free;
                }

                pred->regex.len = len;
                strncpy(pred->regex.pattern, str + s, len);
                pred->regex.pattern[len] = 0;

                filter_build_regex(pred);

                if (field->filter_type == FILTER_COMM) {
                        pred->fn = filter_pred_comm;

                } else if (field->filter_type == FILTER_STATIC_STRING) {
                        pred->fn = filter_pred_string;
                        pred->regex.field_len = field->size;

                } else if (field->filter_type == FILTER_DYN_STRING)
                        pred->fn = filter_pred_strloc;
                else
                        pred->fn = filter_pred_pchar;
                /* go past the last quote */
                i++;

        } else if (isdigit(str[i]) || str[i] == '-') {

                /* Make sure the field is not a string */
                if (is_string_field(field)) {
                        parse_error(pe, FILT_ERR_EXPECT_STRING, pos + i);
                        goto err_free;
                }

                if (op == OP_GLOB) {
                        parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i);
                        goto err_free;
                }

                if (str[i] == '-')
                        i++;

                /* We allow 0xDEADBEEF */
                while (isalnum(str[i]))
                        i++;

                len = i - s;
                /* 0xfeedfacedeadbeef is 18 chars max */
                if (len >= sizeof(num_buf)) {
                        parse_error(pe, FILT_ERR_OPERAND_TOO_LONG, pos + i);
                        goto err_free;
                }

                strncpy(num_buf, str + s, len);
                num_buf[len] = 0;

                /* Make sure it is a value */
                if (field->is_signed)
                        ret = kstrtoll(num_buf, 0, &val);
                else
                        ret = kstrtoull(num_buf, 0, &val);
                if (ret) {
                        parse_error(pe, FILT_ERR_ILLEGAL_INTVAL, pos + s);
                        goto err_free;
                }

                pred->val = val;

                if (field->filter_type == FILTER_CPU)
                        pred->fn = filter_pred_cpu;
                else {
                        pred->fn = select_comparison_fn(pred->op, field->size,
                                                        field->is_signed);
                        if (pred->op == OP_NE)
                                pred->not = 1;
                }

        } else {
                parse_error(pe, FILT_ERR_INVALID_VALUE, pos + i);
                goto err_free;
        }

        *pred_ptr = pred;
        return i;

err_free:
        kfree(pred);
        return -EINVAL;
}

enum {
        TOO_MANY_CLOSE          = -1,
        TOO_MANY_OPEN           = -2,
        MISSING_QUOTE           = -3,
};

/*
 * Read the filter string once to calculate the number of predicates
 * as well as how deep the parentheses go.
 *
 * Returns:
 *   0 - everything is fine (err is undefined)
 *  -1 - too many ')'
 *  -2 - too many '('
 *  -3 - No matching quote
 */
static int calc_stack(const char *str, int *parens, int *preds, int *err)
{
        bool is_pred = false;
        int nr_preds = 0;
        int open = 1; /* Count the expression as "(E)" */
        int last_quote = 0;
        int max_open = 1;
        int quote = 0;
        int i;

        *err = 0;

        for (i = 0; str[i]; i++) {
                if (isspace(str[i]))
                        continue;
                if (quote) {
                        if (str[i] == quote)
                               quote = 0;
                        continue;
                }

                switch (str[i]) {
                case '\'':
                case '"':
                        quote = str[i];
                        last_quote = i;
                        break;
                case '|':
                case '&':
                        if (str[i+1] != str[i])
                                break;
                        is_pred = false;
                        continue;
                case '(':
                        is_pred = false;
                        open++;
                        if (open > max_open)
                                max_open = open;
                        continue;
                case ')':
                        is_pred = false;
                        if (open == 1) {
                                *err = i;
                                return TOO_MANY_CLOSE;
                        }
                        open--;
                        continue;
                }
                if (!is_pred) {
                        nr_preds++;
                        is_pred = true;
                }
        }

        if (quote) {
                *err = last_quote;
                return MISSING_QUOTE;
        }

        if (open != 1) {
                int level = open;

                /* find the bad open */
                for (i--; i; i--) {
                        if (quote) {
                                if (str[i] == quote)
                                        quote = 0;
                                continue;
                        }
                        switch (str[i]) {
                        case '(':
                                if (level == open) {
                                        *err = i;
                                        return TOO_MANY_OPEN;
                                }
                                level--;
                                break;
                        case ')':
                                level++;
                                break;
                        case '\'':
                        case '"':
                                quote = str[i];
                                break;
                        }
                }
                /* First character is the '(' with missing ')' */
                *err = 0;
                return TOO_MANY_OPEN;
        }

        /* Set the size of the required stacks */
        *parens = max_open;
        *preds = nr_preds;
        return 0;
}

static int process_preds(struct trace_event_call *call,
                         const char *filter_string,
                         struct event_filter *filter,
                         struct filter_parse_error *pe)
{
        struct prog_entry *prog;
        int nr_parens;
        int nr_preds;
        int index;
        int ret;

        ret = calc_stack(filter_string, &nr_parens, &nr_preds, &index);
        if (ret < 0) {
                switch (ret) {
                case MISSING_QUOTE:
                        parse_error(pe, FILT_ERR_MISSING_QUOTE, index);
                        break;
                case TOO_MANY_OPEN:
                        parse_error(pe, FILT_ERR_TOO_MANY_OPEN, index);
                        break;
                default:
                        parse_error(pe, FILT_ERR_TOO_MANY_CLOSE, index);
                }
                return ret;
        }

        if (!nr_preds)
                return -EINVAL;

        prog = predicate_parse(filter_string, nr_parens, nr_preds,
                               parse_pred, call, pe);
        if (IS_ERR(prog))
                return PTR_ERR(prog);

        rcu_assign_pointer(filter->prog, prog);
        return 0;
}

static inline void event_set_filtered_flag(struct trace_event_file *file)
{
        unsigned long old_flags = file->flags;

        file->flags |= EVENT_FILE_FL_FILTERED;

        if (old_flags != file->flags)
                trace_buffered_event_enable();
}

static inline void event_set_filter(struct trace_event_file *file,
                                    struct event_filter *filter)
{
        rcu_assign_pointer(file->filter, filter);
}

static inline void event_clear_filter(struct trace_event_file *file)
{
        RCU_INIT_POINTER(file->filter, NULL);
}

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

static int process_system_preds(struct trace_subsystem_dir *dir,
                                struct trace_array *tr,
                                struct filter_parse_error *pe,
                                char *filter_string)
{
        struct trace_event_file *file;
        struct filter_list *filter_item;
        struct event_filter *filter = NULL;
        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;

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

                filter->filter_string = kstrdup(filter_string, GFP_KERNEL);
                if (!filter->filter_string)
                        goto fail_mem;

                err = process_preds(file->event_call, filter_string, filter, pe);
                if (err) {
                        filter_disable(file);
                        parse_error(pe, FILT_ERR_BAD_SUBSYS_FILTER, 0);
                        append_filter_err(tr, pe, filter);
                } else
                        event_set_filtered_flag(file);


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

                list_add_tail(&filter_item->list, &filter_list);
                /*
                 * Regardless of if this returned an error, we still
                 * replace the filter for the call.
                 */
                filter_item->filter = event_filter(file);
                event_set_filter(file, filter);
                filter = NULL;

                fail = false;
        }

        if (fail)
                goto fail;

        /*
         * The calls can still be using the old filters.
         * Do a synchronize_rcu() and to ensure all calls are
         * done with them before we free them.
         */
        tracepoint_synchronize_unregister();
        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(pe, FILT_ERR_BAD_SUBSYS_FILTER, 0);
        return -EINVAL;
 fail_mem:
        __free_filter(filter);
        /* If any call succeeded, we still need to sync */
        if (!fail)
                tracepoint_synchronize_unregister();
        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_string, bool set_str,
                               struct filter_parse_error **pse,
                               struct event_filter **filterp)
{
        struct event_filter *filter;
        struct filter_parse_error *pe = NULL;
        int err = 0;

        if (WARN_ON_ONCE(*pse || *filterp))
                return -EINVAL;

        filter = kzalloc(sizeof(*filter), GFP_KERNEL);
        if (filter && set_str) {
                filter->filter_string = kstrdup(filter_string, GFP_KERNEL);
                if (!filter->filter_string)
                        err = -ENOMEM;
        }

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

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

        /* we're committed to creating a new filter */
        *filterp = filter;
        *pse = pe;

        return 0;
}

static void create_filter_finish(struct filter_parse_error *pe)
{
        kfree(pe);
}

/**
 * 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)
 *           Must be a pointer that references a NULL pointer.
 *
 * 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_array *tr,
                         struct trace_event_call *call,
                         char *filter_string, bool set_str,
                         struct event_filter **filterp)
{
        struct filter_parse_error *pe = NULL;
        int err;

        /* filterp must point to NULL */
        if (WARN_ON(*filterp))
                *filterp = NULL;

        err = create_filter_start(filter_string, set_str, &pe, filterp);
        if (err)
                return err;

        err = process_preds(call, filter_string, *filterp, pe);
        if (err && set_str)
                append_filter_err(tr, pe, *filterp);
        create_filter_finish(pe);

        return err;
}

int create_event_filter(struct trace_array *tr,
                        struct trace_event_call *call,
                        char *filter_str, bool set_str,
                        struct event_filter **filterp)
{
        return create_filter(tr, 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 filter_parse_error *pe = NULL;
        int err;

        err = create_filter_start(filter_str, true, &pe, filterp);
        if (!err) {
                err = process_system_preds(dir, tr, pe, filter_str);
                if (!err) {
                        /* System filters just show a default message */
                        kfree((*filterp)->filter_string);
                        (*filterp)->filter_string = NULL;
                } else {
                        append_filter_err(tr, pe, *filterp);
                }
        }
        create_filter_finish(pe);

        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 = NULL;
        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 */
                tracepoint_synchronize_unregister();
                __free_filter(filter);

                return 0;
        }

        err = create_filter(file->tr, 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 */
                        tracepoint_synchronize_unregister();
                        __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 = NULL;
        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 */
                tracepoint_synchronize_unregister();
                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_rcu().
                 */
                __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 separately.
         */
        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)
{
        struct ftrace_event_field *field = pred->field;

        /*
         * Check the 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;

        return 0;
}

static int ftrace_function_set_filter_pred(struct filter_pred *pred,
                                           struct function_filter_data *data)
{
        int ret;

        /* Checking the node is valid for function trace. */
        ret = ftrace_function_check_pred(pred);
        if (ret)
                return ret;

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

static bool is_or(struct prog_entry *prog, int i)
{
        int target;

        /*
         * Only "||" is allowed for function events, thus,
         * all true branches should jump to true, and any
         * false branch should jump to false.
         */
        target = prog[i].target + 1;
        /* True and false have NULL preds (all prog entries should jump to one */
        if (prog[target].pred)
                return false;

        /* prog[target].target is 1 for TRUE, 0 for FALSE */
        return prog[i].when_to_branch == prog[target].target;
}

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

        for (i = 0; prog[i].pred; i++) {
                struct filter_pred *pred = prog[i].pred;

                if (!is_or(prog, i))
                        return -EINVAL;

                if (ftrace_function_set_filter_pred(pred, &data) < 0)
                        return -EINVAL;
        }
        return 0;
}
#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 = NULL;
        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(NULL, 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 ARRAY_SIZE(test_filter_data)

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 void update_pred_fn(struct event_filter *filter, char *fields)
{
        struct prog_entry *prog = rcu_dereference_protected(filter->prog,
                                                lockdep_is_held(&event_mutex));
        int i;

        for (i = 0; prog[i].pred; i++) {
                struct filter_pred *pred = prog[i].pred;
                struct ftrace_event_field *field = pred->field;

                WARN_ON_ONCE(!pred->fn);

                if (!field) {
                        WARN_ONCE(1, "all leafs should have field defined %d", i);
                        continue;
                }

                if (!strchr(fields, *field->name))
                        continue;

                pred->fn = test_pred_visited_fn;
        }
}

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(NULL, &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;
                }

                /* Needed to dereference filter->prog */
                mutex_lock(&event_mutex);
                /*
                 * The preemption disabling is not really needed for self
                 * tests, but the rcu dereference will complain without it.
                 */
                preempt_disable();
                if (*d->not_visited)
                        update_pred_fn(filter, d->not_visited);

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

                mutex_unlock(&event_mutex);

                __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 */