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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * trace_events_filter - generic event filtering
  *
  * Copyright (C) 2009 Tom Zanussi <tzanussi@gmail.com>
  */
 
 #include <linux/uaccess.h>
 #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
  * calling 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 program 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 interpret 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);
 
 /* user space strings temp buffer */
 #define USTRING_BUF_SIZE    1024
 
 struct ustring_buffer {
     char        buffer[USTRING_BUF_SIZE];
 };
 
 static __percpu struct ustring_buffer *ustring_per_cpu;
 
 static __always_inline char *test_string(char *str)
 {
     struct ustring_buffer *ubuf;
     char *kstr;
 
     if (!ustring_per_cpu)
         return NULL;
 
     ubuf = this_cpu_ptr(ustring_per_cpu);
     kstr = ubuf->buffer;
 
     /* For safety, do not trust the string pointer */
     if (!strncpy_from_kernel_nofault(kstr, str, USTRING_BUF_SIZE))
         return NULL;
     return kstr;
 }
 
 static __always_inline char *test_ustring(char *str)
 {
     struct ustring_buffer *ubuf;
     char __user *ustr;
     char *kstr;
 
     if (!ustring_per_cpu)
         return NULL;
 
     ubuf = this_cpu_ptr(ustring_per_cpu);
     kstr = ubuf->buffer;
 
     /* user space address? */
     ustr = (char __user *)str;
     if (!strncpy_from_user_nofault(kstr, ustr, USTRING_BUF_SIZE))
         return NULL;
 
     return kstr;
 }
 
 /* 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;
 }
 
 static __always_inline int filter_pchar(struct filter_pred *pred, char *str)
 {
     int cmp, match;
     int len;
 
     len = strlen(str) + 1;  /* including tailing '\0' */
     cmp = pred->regex.match(str, &pred->regex, 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);
     char *str;
 
     str = test_string(*addr);
     if (!str)
         return 0;
 
     return filter_pchar(pred, str);
 }
 
 /* Filter predicate for char * pointers in user space*/
 static int filter_pred_pchar_user(struct filter_pred *pred, void *event)
 {
     char **addr = (char **)(event + pred->offset);
     char *str;
 
     str = test_ustring(*addr);
     if (!str)
         return 0;
 
     return filter_pchar(pred, str);
 }
 
 /*
  * 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 relative dynamic sized arrays of characters.
  * These are implemented through a list of strings at the end
  * of the entry as same as dynamic string.
  * The difference is that the relative one records the location offset
  * from the field itself, not the event entry.
  */
 static int filter_pred_strrelloc(struct filter_pred *pred, void *event)
 {
     u32 *item = (u32 *)(event + pred->offset);
     u32 str_item = *item;
     int str_loc = str_item & 0xffff;
     int str_len = str_item >> 16;
     char *addr = (char *)(&item[1]) + 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
  *   RDYN_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 (strstr(type, "__rel_loc") && strstr(type, "char"))
         return FILTER_RDYN_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;
     bool ustring = false;
     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;
     }
 
     /* See if the field is a user space string */
     if ((len = str_has_prefix(str + i, ".ustring"))) {
         ustring = true;
         i += len;
     }
 
     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 if (field->filter_type == FILTER_RDYN_STRING)
             pred->fn = filter_pred_strrelloc;
         else {
 
             if (!ustring_per_cpu) {
                 /* Once allocated, keep it around for good */
                 ustring_per_cpu = alloc_percpu(struct ustring_buffer);
                 if (!ustring_per_cpu)
                     goto err_mem;
             }
 
             if (ustring)
                 pred->fn = filter_pred_pchar_user;
             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;
 err_mem:
     kfree(pred);
     return -ENOMEM;
 }
 
 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
  * @tr: the trace array associated with these events
  * @call: trace_event_call to create a filter for
  * @filter_string: 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
  * @dir: the descriptor for the subsystem directory
  * @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,
                 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, 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(dir->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, 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 */

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