| 1 | /* DWARF 2 Expression Evaluator. |
| 2 | |
| 3 | Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008, 2009, 2010, 2011 |
| 4 | Free Software Foundation, Inc. |
| 5 | |
| 6 | Contributed by Daniel Berlin <dan@dberlin.org>. |
| 7 | |
| 8 | This file is part of GDB. |
| 9 | |
| 10 | This program is free software; you can redistribute it and/or modify |
| 11 | it under the terms of the GNU General Public License as published by |
| 12 | the Free Software Foundation; either version 3 of the License, or |
| 13 | (at your option) any later version. |
| 14 | |
| 15 | This program is distributed in the hope that it will be useful, |
| 16 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | GNU General Public License for more details. |
| 19 | |
| 20 | You should have received a copy of the GNU General Public License |
| 21 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 22 | |
| 23 | #if !defined (DWARF2EXPR_H) |
| 24 | #define DWARF2EXPR_H |
| 25 | |
| 26 | /* The location of a value. */ |
| 27 | enum dwarf_value_location |
| 28 | { |
| 29 | /* The piece is in memory. |
| 30 | The value on the dwarf stack is its address. */ |
| 31 | DWARF_VALUE_MEMORY, |
| 32 | |
| 33 | /* The piece is in a register. |
| 34 | The value on the dwarf stack is the register number. */ |
| 35 | DWARF_VALUE_REGISTER, |
| 36 | |
| 37 | /* The piece is on the dwarf stack. */ |
| 38 | DWARF_VALUE_STACK, |
| 39 | |
| 40 | /* The piece is a literal. */ |
| 41 | DWARF_VALUE_LITERAL, |
| 42 | |
| 43 | /* The piece was optimized out. */ |
| 44 | DWARF_VALUE_OPTIMIZED_OUT, |
| 45 | |
| 46 | /* The piece is an implicit pointer. */ |
| 47 | DWARF_VALUE_IMPLICIT_POINTER |
| 48 | }; |
| 49 | |
| 50 | /* The dwarf expression stack. */ |
| 51 | |
| 52 | struct dwarf_stack_value |
| 53 | { |
| 54 | ULONGEST value; |
| 55 | |
| 56 | /* Non-zero if the piece is in memory and is known to be |
| 57 | on the program's stack. It is always ok to set this to zero. |
| 58 | This is used, for example, to optimize memory access from the target. |
| 59 | It can vastly speed up backtraces on long latency connections when |
| 60 | "set stack-cache on". */ |
| 61 | int in_stack_memory; |
| 62 | }; |
| 63 | |
| 64 | /* The expression evaluator works with a dwarf_expr_context, describing |
| 65 | its current state and its callbacks. */ |
| 66 | struct dwarf_expr_context |
| 67 | { |
| 68 | /* The stack of values, allocated with xmalloc. */ |
| 69 | struct dwarf_stack_value *stack; |
| 70 | |
| 71 | /* The number of values currently pushed on the stack, and the |
| 72 | number of elements allocated to the stack. */ |
| 73 | int stack_len, stack_allocated; |
| 74 | |
| 75 | /* Target architecture to use for address operations. */ |
| 76 | struct gdbarch *gdbarch; |
| 77 | |
| 78 | /* Target address size in bytes. */ |
| 79 | int addr_size; |
| 80 | |
| 81 | /* Offset used to relocate DW_OP_addr argument. */ |
| 82 | CORE_ADDR offset; |
| 83 | |
| 84 | /* An opaque argument provided by the caller, which will be passed |
| 85 | to all of the callback functions. */ |
| 86 | void *baton; |
| 87 | |
| 88 | /* Return the value of register number REGNUM. */ |
| 89 | CORE_ADDR (*read_reg) (void *baton, int regnum); |
| 90 | |
| 91 | /* Read LENGTH bytes at ADDR into BUF. */ |
| 92 | void (*read_mem) (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t length); |
| 93 | |
| 94 | /* Return the location expression for the frame base attribute, in |
| 95 | START and LENGTH. The result must be live until the current |
| 96 | expression evaluation is complete. */ |
| 97 | void (*get_frame_base) (void *baton, const gdb_byte **start, size_t *length); |
| 98 | |
| 99 | /* Return the CFA for the frame. */ |
| 100 | CORE_ADDR (*get_frame_cfa) (void *baton); |
| 101 | |
| 102 | /* Return the PC for the frame. */ |
| 103 | CORE_ADDR (*get_frame_pc) (void *baton); |
| 104 | |
| 105 | /* Return the thread-local storage address for |
| 106 | DW_OP_GNU_push_tls_address. */ |
| 107 | CORE_ADDR (*get_tls_address) (void *baton, CORE_ADDR offset); |
| 108 | |
| 109 | /* Execute DW_AT_location expression for the DWARF expression subroutine in |
| 110 | the DIE at DIE_OFFSET in the CU from CTX. Do not touch STACK while it |
| 111 | being passed to and returned from the called DWARF subroutine. */ |
| 112 | void (*dwarf_call) (struct dwarf_expr_context *ctx, size_t die_offset); |
| 113 | |
| 114 | #if 0 |
| 115 | /* Not yet implemented. */ |
| 116 | |
| 117 | /* Return the `object address' for DW_OP_push_object_address. */ |
| 118 | CORE_ADDR (*get_object_address) (void *baton); |
| 119 | #endif |
| 120 | |
| 121 | /* The current depth of dwarf expression recursion, via DW_OP_call*, |
| 122 | DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum |
| 123 | depth we'll tolerate before raising an error. */ |
| 124 | int recursion_depth, max_recursion_depth; |
| 125 | |
| 126 | /* Location of the value. */ |
| 127 | enum dwarf_value_location location; |
| 128 | |
| 129 | /* For DWARF_VALUE_LITERAL, the current literal value's length and |
| 130 | data. For DWARF_VALUE_IMPLICIT_POINTER, LEN is the offset of the |
| 131 | target DIE. */ |
| 132 | ULONGEST len; |
| 133 | const gdb_byte *data; |
| 134 | |
| 135 | /* Initialization status of variable: Non-zero if variable has been |
| 136 | initialized; zero otherwise. */ |
| 137 | int initialized; |
| 138 | |
| 139 | /* An array of pieces. PIECES points to its first element; |
| 140 | NUM_PIECES is its length. |
| 141 | |
| 142 | Each time DW_OP_piece is executed, we add a new element to the |
| 143 | end of this array, recording the current top of the stack, the |
| 144 | current location, and the size given as the operand to |
| 145 | DW_OP_piece. We then pop the top value from the stack, reset the |
| 146 | location, and resume evaluation. |
| 147 | |
| 148 | The Dwarf spec doesn't say whether DW_OP_piece pops the top value |
| 149 | from the stack. We do, ensuring that clients of this interface |
| 150 | expecting to see a value left on the top of the stack (say, code |
| 151 | evaluating frame base expressions or CFA's specified with |
| 152 | DW_CFA_def_cfa_expression) will get an error if the expression |
| 153 | actually marks all the values it computes as pieces. |
| 154 | |
| 155 | If an expression never uses DW_OP_piece, num_pieces will be zero. |
| 156 | (It would be nice to present these cases as expressions yielding |
| 157 | a single piece, so that callers need not distinguish between the |
| 158 | no-DW_OP_piece and one-DW_OP_piece cases. But expressions with |
| 159 | no DW_OP_piece operations have no value to place in a piece's |
| 160 | 'size' field; the size comes from the surrounding data. So the |
| 161 | two cases need to be handled separately.) */ |
| 162 | int num_pieces; |
| 163 | struct dwarf_expr_piece *pieces; |
| 164 | }; |
| 165 | |
| 166 | |
| 167 | /* A piece of an object, as recorded by DW_OP_piece or DW_OP_bit_piece. */ |
| 168 | struct dwarf_expr_piece |
| 169 | { |
| 170 | enum dwarf_value_location location; |
| 171 | |
| 172 | union |
| 173 | { |
| 174 | struct |
| 175 | { |
| 176 | /* This piece's address, for DWARF_VALUE_MEMORY pieces. */ |
| 177 | CORE_ADDR addr; |
| 178 | /* Non-zero if the piece is known to be in memory and on |
| 179 | the program's stack. */ |
| 180 | int in_stack_memory; |
| 181 | } mem; |
| 182 | |
| 183 | /* The piece's register number or literal value, for |
| 184 | DWARF_VALUE_REGISTER or DWARF_VALUE_STACK pieces. */ |
| 185 | ULONGEST value; |
| 186 | |
| 187 | struct |
| 188 | { |
| 189 | /* A pointer to the data making up this piece, |
| 190 | for DWARF_VALUE_LITERAL pieces. */ |
| 191 | const gdb_byte *data; |
| 192 | /* The length of the available data. */ |
| 193 | ULONGEST length; |
| 194 | } literal; |
| 195 | |
| 196 | /* Used for DWARF_VALUE_IMPLICIT_POINTER. */ |
| 197 | struct |
| 198 | { |
| 199 | /* The referent DIE from DW_OP_GNU_implicit_pointer. */ |
| 200 | ULONGEST die; |
| 201 | /* The byte offset into the resulting data. */ |
| 202 | LONGEST offset; |
| 203 | } ptr; |
| 204 | } v; |
| 205 | |
| 206 | /* The length of the piece, in bits. */ |
| 207 | ULONGEST size; |
| 208 | /* The piece offset, in bits. */ |
| 209 | ULONGEST offset; |
| 210 | }; |
| 211 | |
| 212 | struct dwarf_expr_context *new_dwarf_expr_context (void); |
| 213 | void free_dwarf_expr_context (struct dwarf_expr_context *ctx); |
| 214 | struct cleanup * |
| 215 | make_cleanup_free_dwarf_expr_context (struct dwarf_expr_context *ctx); |
| 216 | |
| 217 | void dwarf_expr_push (struct dwarf_expr_context *ctx, ULONGEST value, |
| 218 | int in_stack_memory); |
| 219 | void dwarf_expr_pop (struct dwarf_expr_context *ctx); |
| 220 | void dwarf_expr_eval (struct dwarf_expr_context *ctx, const gdb_byte *addr, |
| 221 | size_t len); |
| 222 | ULONGEST dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n); |
| 223 | CORE_ADDR dwarf_expr_fetch_address (struct dwarf_expr_context *ctx, int n); |
| 224 | int dwarf_expr_fetch_in_stack_memory (struct dwarf_expr_context *ctx, int n); |
| 225 | |
| 226 | |
| 227 | const gdb_byte *read_uleb128 (const gdb_byte *buf, const gdb_byte *buf_end, |
| 228 | ULONGEST * r); |
| 229 | const gdb_byte *read_sleb128 (const gdb_byte *buf, const gdb_byte *buf_end, |
| 230 | LONGEST * r); |
| 231 | |
| 232 | const char *dwarf_stack_op_name (unsigned int); |
| 233 | |
| 234 | void dwarf_expr_require_composition (const gdb_byte *, const gdb_byte *, |
| 235 | const char *); |
| 236 | |
| 237 | #endif /* dwarf2expr.h */ |