| 1 | /* Definitions for expressions designed to be executed on the agent |
| 2 | Copyright (C) 1998, 1999, 2000, 2007, 2008, 2009, 2010 |
| 3 | Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of GDB. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | #ifndef AGENTEXPR_H |
| 21 | #define AGENTEXPR_H |
| 22 | |
| 23 | #include "doublest.h" /* For DOUBLEST. */ |
| 24 | |
| 25 | /* It's sometimes useful to be able to debug programs that you can't |
| 26 | really stop for more than a fraction of a second. To this end, the |
| 27 | user can specify a tracepoint (like a breakpoint, but you don't |
| 28 | stop at it), and specify a bunch of expressions to record the |
| 29 | values of when that tracepoint is reached. As the program runs, |
| 30 | GDB collects the values. At any point (possibly while values are |
| 31 | still being collected), the user can display the collected values. |
| 32 | |
| 33 | This is used with remote debugging; we don't really support it on |
| 34 | native configurations. |
| 35 | |
| 36 | This means that expressions are being evaluated by the remote agent, |
| 37 | which doesn't have any access to the symbol table information, and |
| 38 | needs to be small and simple. |
| 39 | |
| 40 | The agent_expr routines and datatypes are a bytecode language |
| 41 | designed to be executed by the agent. Agent expressions work in |
| 42 | terms of fixed-width values, operators, memory references, and |
| 43 | register references. You can evaluate a agent expression just given |
| 44 | a bunch of memory and register values to sniff at; you don't need |
| 45 | any symbolic information like variable names, types, etc. |
| 46 | |
| 47 | GDB translates source expressions, whose meaning depends on |
| 48 | symbolic information, into agent bytecode expressions, whose meaning |
| 49 | is independent of symbolic information. This means the agent can |
| 50 | evaluate them on the fly without reference to data only available |
| 51 | to the host GDB. */ |
| 52 | \f |
| 53 | |
| 54 | /* Agent expression data structures. */ |
| 55 | |
| 56 | /* The type of an element of the agent expression stack. |
| 57 | The bytecode operation indicates which element we should access; |
| 58 | the value itself has no typing information. GDB generates all |
| 59 | bytecode streams, so we don't have to worry about type errors. */ |
| 60 | |
| 61 | union agent_val |
| 62 | { |
| 63 | LONGEST l; |
| 64 | DOUBLEST d; |
| 65 | }; |
| 66 | |
| 67 | /* A buffer containing a agent expression. */ |
| 68 | struct agent_expr |
| 69 | { |
| 70 | unsigned char *buf; |
| 71 | int len; /* number of characters used */ |
| 72 | int size; /* allocated size */ |
| 73 | CORE_ADDR scope; |
| 74 | }; |
| 75 | |
| 76 | |
| 77 | |
| 78 | |
| 79 | /* The actual values of the various bytecode operations. |
| 80 | |
| 81 | Other independent implementations of the agent bytecode engine will |
| 82 | rely on the exact values of these enums, and may not be recompiled |
| 83 | when we change this table. The numeric values should remain fixed |
| 84 | whenever possible. Thus, we assign them values explicitly here (to |
| 85 | allow gaps to form safely), and the disassembly table in |
| 86 | agentexpr.h behaves like an opcode map. If you want to see them |
| 87 | grouped logically, see doc/agentexpr.texi. */ |
| 88 | |
| 89 | enum agent_op |
| 90 | { |
| 91 | aop_float = 0x01, |
| 92 | aop_add = 0x02, |
| 93 | aop_sub = 0x03, |
| 94 | aop_mul = 0x04, |
| 95 | aop_div_signed = 0x05, |
| 96 | aop_div_unsigned = 0x06, |
| 97 | aop_rem_signed = 0x07, |
| 98 | aop_rem_unsigned = 0x08, |
| 99 | aop_lsh = 0x09, |
| 100 | aop_rsh_signed = 0x0a, |
| 101 | aop_rsh_unsigned = 0x0b, |
| 102 | aop_trace = 0x0c, |
| 103 | aop_trace_quick = 0x0d, |
| 104 | aop_log_not = 0x0e, |
| 105 | aop_bit_and = 0x0f, |
| 106 | aop_bit_or = 0x10, |
| 107 | aop_bit_xor = 0x11, |
| 108 | aop_bit_not = 0x12, |
| 109 | aop_equal = 0x13, |
| 110 | aop_less_signed = 0x14, |
| 111 | aop_less_unsigned = 0x15, |
| 112 | aop_ext = 0x16, |
| 113 | aop_ref8 = 0x17, |
| 114 | aop_ref16 = 0x18, |
| 115 | aop_ref32 = 0x19, |
| 116 | aop_ref64 = 0x1a, |
| 117 | aop_ref_float = 0x1b, |
| 118 | aop_ref_double = 0x1c, |
| 119 | aop_ref_long_double = 0x1d, |
| 120 | aop_l_to_d = 0x1e, |
| 121 | aop_d_to_l = 0x1f, |
| 122 | aop_if_goto = 0x20, |
| 123 | aop_goto = 0x21, |
| 124 | aop_const8 = 0x22, |
| 125 | aop_const16 = 0x23, |
| 126 | aop_const32 = 0x24, |
| 127 | aop_const64 = 0x25, |
| 128 | aop_reg = 0x26, |
| 129 | aop_end = 0x27, |
| 130 | aop_dup = 0x28, |
| 131 | aop_pop = 0x29, |
| 132 | aop_zero_ext = 0x2a, |
| 133 | aop_swap = 0x2b, |
| 134 | aop_getv = 0x2c, |
| 135 | aop_setv = 0x2d, |
| 136 | aop_tracev = 0x2e, |
| 137 | aop_trace16 = 0x30, |
| 138 | aop_last |
| 139 | }; |
| 140 | \f |
| 141 | |
| 142 | |
| 143 | /* Functions for building expressions. */ |
| 144 | |
| 145 | /* Allocate a new, empty agent expression. */ |
| 146 | extern struct agent_expr *new_agent_expr (CORE_ADDR); |
| 147 | |
| 148 | /* Free a agent expression. */ |
| 149 | extern void free_agent_expr (struct agent_expr *); |
| 150 | extern struct cleanup *make_cleanup_free_agent_expr (struct agent_expr *); |
| 151 | |
| 152 | /* Append a simple operator OP to EXPR. */ |
| 153 | extern void ax_simple (struct agent_expr *EXPR, enum agent_op OP); |
| 154 | |
| 155 | /* Append the floating-point prefix, for the next bytecode. */ |
| 156 | #define ax_float(EXPR) (ax_simple ((EXPR), aop_float)) |
| 157 | |
| 158 | /* Append a sign-extension instruction to EXPR, to extend an N-bit value. */ |
| 159 | extern void ax_ext (struct agent_expr *EXPR, int N); |
| 160 | |
| 161 | /* Append a zero-extension instruction to EXPR, to extend an N-bit value. */ |
| 162 | extern void ax_zero_ext (struct agent_expr *EXPR, int N); |
| 163 | |
| 164 | /* Append a trace_quick instruction to EXPR, to record N bytes. */ |
| 165 | extern void ax_trace_quick (struct agent_expr *EXPR, int N); |
| 166 | |
| 167 | /* Append a goto op to EXPR. OP is the actual op (must be aop_goto or |
| 168 | aop_if_goto). We assume we don't know the target offset yet, |
| 169 | because it's probably a forward branch, so we leave space in EXPR |
| 170 | for the target, and return the offset in EXPR of that space, so we |
| 171 | can backpatch it once we do know the target offset. Use ax_label |
| 172 | to do the backpatching. */ |
| 173 | extern int ax_goto (struct agent_expr *EXPR, enum agent_op OP); |
| 174 | |
| 175 | /* Suppose a given call to ax_goto returns some value PATCH. When you |
| 176 | know the offset TARGET that goto should jump to, call |
| 177 | ax_label (EXPR, PATCH, TARGET) |
| 178 | to patch TARGET into the ax_goto instruction. */ |
| 179 | extern void ax_label (struct agent_expr *EXPR, int patch, int target); |
| 180 | |
| 181 | /* Assemble code to push a constant on the stack. */ |
| 182 | extern void ax_const_l (struct agent_expr *EXPR, LONGEST l); |
| 183 | extern void ax_const_d (struct agent_expr *EXPR, LONGEST d); |
| 184 | |
| 185 | /* Assemble code to push the value of register number REG on the |
| 186 | stack. */ |
| 187 | extern void ax_reg (struct agent_expr *EXPR, int REG); |
| 188 | |
| 189 | /* Assemble code to operate on a trace state variable. */ |
| 190 | extern void ax_tsv (struct agent_expr *expr, enum agent_op op, int num); |
| 191 | \f |
| 192 | |
| 193 | /* Functions for printing out expressions, and otherwise debugging |
| 194 | things. */ |
| 195 | |
| 196 | /* Disassemble the expression EXPR, writing to F. */ |
| 197 | extern void ax_print (struct ui_file *f, struct agent_expr * EXPR); |
| 198 | |
| 199 | /* An entry in the opcode map. */ |
| 200 | struct aop_map |
| 201 | { |
| 202 | |
| 203 | /* The name of the opcode. Null means that this entry is not a |
| 204 | valid opcode --- a hole in the opcode space. */ |
| 205 | char *name; |
| 206 | |
| 207 | /* All opcodes take no operands from the bytecode stream, or take |
| 208 | unsigned integers of various sizes. If this is a positive number |
| 209 | n, then the opcode is followed by an n-byte operand, which should |
| 210 | be printed as an unsigned integer. If this is zero, then the |
| 211 | opcode takes no operands from the bytecode stream. |
| 212 | |
| 213 | If we get more complicated opcodes in the future, don't add other |
| 214 | magic values of this; that's a crock. Add an `enum encoding' |
| 215 | field to this, or something like that. */ |
| 216 | int op_size; |
| 217 | |
| 218 | /* The size of the data operated upon, in bits, for bytecodes that |
| 219 | care about that (ref and const). Zero for all others. */ |
| 220 | int data_size; |
| 221 | |
| 222 | /* Number of stack elements consumed, and number produced. */ |
| 223 | int consumed, produced; |
| 224 | }; |
| 225 | |
| 226 | /* Map of the bytecodes, indexed by bytecode number. */ |
| 227 | extern struct aop_map aop_map[]; |
| 228 | |
| 229 | /* Different kinds of flaws an agent expression might have, as |
| 230 | detected by agent_reqs. */ |
| 231 | enum agent_flaws |
| 232 | { |
| 233 | agent_flaw_none = 0, /* code is good */ |
| 234 | |
| 235 | /* There is an invalid instruction in the stream. */ |
| 236 | agent_flaw_bad_instruction, |
| 237 | |
| 238 | /* There is an incomplete instruction at the end of the expression. */ |
| 239 | agent_flaw_incomplete_instruction, |
| 240 | |
| 241 | /* agent_reqs was unable to prove that every jump target is to a |
| 242 | valid offset. Valid offsets are within the bounds of the |
| 243 | expression, and to a valid instruction boundary. */ |
| 244 | agent_flaw_bad_jump, |
| 245 | |
| 246 | /* agent_reqs was unable to prove to its satisfaction that, for each |
| 247 | jump target location, the stack will have the same height whether |
| 248 | that location is reached via a jump or by straight execution. */ |
| 249 | agent_flaw_height_mismatch, |
| 250 | |
| 251 | /* agent_reqs was unable to prove that every instruction following |
| 252 | an unconditional jump was the target of some other jump. */ |
| 253 | agent_flaw_hole |
| 254 | }; |
| 255 | |
| 256 | /* Structure describing the requirements of a bytecode expression. */ |
| 257 | struct agent_reqs |
| 258 | { |
| 259 | |
| 260 | /* If the following is not equal to agent_flaw_none, the rest of the |
| 261 | information in this structure is suspect. */ |
| 262 | enum agent_flaws flaw; |
| 263 | |
| 264 | /* Number of elements left on stack at end; may be negative if expr |
| 265 | only consumes elements. */ |
| 266 | int final_height; |
| 267 | |
| 268 | /* Maximum and minimum stack height, relative to initial height. */ |
| 269 | int max_height, min_height; |
| 270 | |
| 271 | /* Largest `ref' or `const' opcode used, in bits. Zero means the |
| 272 | expression has no such instructions. */ |
| 273 | int max_data_size; |
| 274 | |
| 275 | /* Bit vector of registers used. Register R is used iff |
| 276 | |
| 277 | reg_mask[R / 8] & (1 << (R % 8)) |
| 278 | |
| 279 | is non-zero. Note! You may not assume that this bitmask is long |
| 280 | enough to hold bits for all the registers of the machine; the |
| 281 | agent expression code has no idea how many registers the machine |
| 282 | has. However, the bitmask is reg_mask_len bytes long, so the |
| 283 | valid register numbers run from 0 to reg_mask_len * 8 - 1. |
| 284 | |
| 285 | We're assuming eight-bit bytes. So sue me. |
| 286 | |
| 287 | The caller should free reg_list when done. */ |
| 288 | int reg_mask_len; |
| 289 | unsigned char *reg_mask; |
| 290 | }; |
| 291 | |
| 292 | |
| 293 | /* Given an agent expression AX, fill in an agent_reqs structure REQS |
| 294 | describing it. */ |
| 295 | extern void ax_reqs (struct agent_expr *ax, struct agent_reqs *reqs); |
| 296 | |
| 297 | #endif /* AGENTEXPR_H */ |