lttng-filter.h

   1 #ifndef _LTTNG_FILTER_H
   2 #define _LTTNG_FILTER_H
   3
   4 /*
   5  * lttng-filter.h
   6  *
   7  * LTTng modules filter header.
   8  *
   9  * Copyright (C) 2010-2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a copy
  12  * of this software and associated documentation files (the "Software"), to deal
  13  * in the Software without restriction, including without limitation the rights
  14  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  15  * copies of the Software, and to permit persons to whom the Software is
  16  * furnished to do so, subject to the following conditions:
  17  *
  18  * The above copyright notice and this permission notice shall be included in
  19  * all copies or substantial portions of the Software.
  20  *
  21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  24  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  25  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  26  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  27  * SOFTWARE.
  28  */
  29
  30 #include <linux/kernel.h>
  31
  32 #include <lttng-events.h>
  33 #include <filter-bytecode.h>
  34
  35 /* Filter stack length, in number of entries */
  36 #define FILTER_STACK_LEN        10      /* includes 2 dummy */
  37 #define FILTER_STACK_EMPTY      1
  38
  39 #ifdef DEBUG
  40 #define dbg_printk(fmt, args...)                                \
  41         printk(KERN_DEBUG "[debug bytecode in %s:%s@%u] " fmt,          \
  42                 __FILE__, __func__, __LINE__, ## args)
  43 #else
  44 #define dbg_printk(fmt, args...)                                \
  45 do {                                                            \
  46         /* do nothing but check printf format */                \
  47         if (0)                                                  \
  48                 printk(KERN_DEBUG "[debug bytecode in %s:%s@%u] " fmt,  \
  49                         __FILE__, __func__, __LINE__, ## args); \
  50 } while (0)
  51 #endif
  52
  53 /* Linked bytecode. Child of struct lttng_bytecode_runtime. */
  54 struct bytecode_runtime {
  55         struct lttng_bytecode_runtime p;
  56         uint16_t len;
  57         char data[0];
  58 };
  59
  60 enum entry_type {
  61         REG_S64,
  62         REG_DOUBLE,
  63         REG_STRING,
  64         REG_TYPE_UNKNOWN,
  65 };
  66
  67 /* Validation stack */
  68 struct vstack_entry {
  69         enum entry_type type;
  70 };
  71
  72 struct vstack {
  73         int top;        /* top of stack */
  74         struct vstack_entry e[FILTER_STACK_LEN];
  75 };
  76
  77 static inline
  78 void vstack_init(struct vstack *stack)
  79 {
  80         stack->top = -1;
  81 }
  82
  83 static inline
  84 struct vstack_entry *vstack_ax(struct vstack *stack)
  85 {
  86         if (unlikely(stack->top < 0))
  87                 return NULL;
  88         return &stack->e[stack->top];
  89 }
  90
  91 static inline
  92 struct vstack_entry *vstack_bx(struct vstack *stack)
  93 {
  94         if (unlikely(stack->top < 1))
  95                 return NULL;
  96         return &stack->e[stack->top - 1];
  97 }
  98
  99 static inline
 100 int vstack_push(struct vstack *stack)
 101 {
 102         if (stack->top >= FILTER_STACK_LEN - 1) {
 103                 printk(KERN_WARNING "Stack full\n");
 104                 return -EINVAL;
 105         }
 106         ++stack->top;
 107         return 0;
 108 }
 109
 110 static inline
 111 int vstack_pop(struct vstack *stack)
 112 {
 113         if (unlikely(stack->top < 0)) {
 114                 printk(KERN_WARNING "Stack empty\n");
 115                 return -EINVAL;
 116         }
 117         stack->top--;
 118         return 0;
 119 }
 120
 121 /* Execution stack */
 122 struct estack_entry {
 123         union {
 124                 int64_t v;
 125
 126                 struct {
 127                         const char *str;
 128                         const char __user *user_str;
 129                         size_t seq_len;
 130                         int literal;            /* is string literal ? */
 131                         int user;               /* is string from userspace ? */
 132                 } s;
 133         } u;
 134 };
 135
 136 struct estack {
 137         int top;        /* top of stack */
 138         struct estack_entry e[FILTER_STACK_LEN];
 139 };
 140
 141 #define estack_ax_v     ax
 142 #define estack_bx_v     bx
 143
 144 #define estack_ax(stack, top)                                   \
 145         ({                                                      \
 146                 BUG_ON((top) <= FILTER_STACK_EMPTY);            \
 147                 &(stack)->e[top];                               \
 148         })
 149
 150 #define estack_bx(stack, top)                                   \
 151         ({                                                      \
 152                 BUG_ON((top) <= FILTER_STACK_EMPTY + 1);        \
 153                 &(stack)->e[(top) - 1];                         \
 154         })
 155
 156 #define estack_push(stack, top, ax, bx)                         \
 157         do {                                                    \
 158                 BUG_ON((top) >= FILTER_STACK_LEN - 1);          \
 159                 (stack)->e[(top) - 1].u.v = (bx);               \
 160                 (bx) = (ax);                                    \
 161                 ++(top);                                        \
 162         } while (0)
 163
 164 #define estack_pop(stack, top, ax, bx)                          \
 165         do {                                                    \
 166                 BUG_ON((top) <= FILTER_STACK_EMPTY);            \
 167                 (ax) = (bx);                                    \
 168                 (bx) = (stack)->e[(top) - 2].u.v;               \
 169                 (top)--;                                        \
 170         } while (0)
 171
 172 const char *lttng_filter_print_op(enum filter_op op);
 173
 174 int lttng_filter_validate_bytecode(struct bytecode_runtime *bytecode);
 175 int lttng_filter_specialize_bytecode(struct bytecode_runtime *bytecode);
 176
 177 uint64_t lttng_filter_false(void *filter_data,
 178                 struct lttng_probe_ctx *lttng_probe_ctx,
 179                 const char *filter_stack_data);
 180 uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 181                 struct lttng_probe_ctx *lttng_probe_ctx,
 182                 const char *filter_stack_data);
 183
 184 #endif /* _LTTNG_FILTER_H */