| 1 | /* DWARF 2 Expression Evaluator. |
| 2 | |
| 3 | Copyright (C) 2001-2018 Free Software Foundation, Inc. |
| 4 | |
| 5 | Contributed by Daniel Berlin <dan@dberlin.org>. |
| 6 | |
| 7 | This file is part of GDB. |
| 8 | |
| 9 | This program is free software; you can redistribute it and/or modify |
| 10 | it under the terms of the GNU General Public License as published by |
| 11 | the Free Software Foundation; either version 3 of the License, or |
| 12 | (at your option) any later version. |
| 13 | |
| 14 | This program is distributed in the hope that it will be useful, |
| 15 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 17 | GNU General Public License for more details. |
| 18 | |
| 19 | You should have received a copy of the GNU General Public License |
| 20 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 21 | |
| 22 | #if !defined (DWARF2EXPR_H) |
| 23 | #define DWARF2EXPR_H |
| 24 | |
| 25 | #include "leb128.h" |
| 26 | #include "gdbtypes.h" |
| 27 | |
| 28 | /* The location of a value. */ |
| 29 | enum dwarf_value_location |
| 30 | { |
| 31 | /* The piece is in memory. |
| 32 | The value on the dwarf stack is its address. */ |
| 33 | DWARF_VALUE_MEMORY, |
| 34 | |
| 35 | /* The piece is in a register. |
| 36 | The value on the dwarf stack is the register number. */ |
| 37 | DWARF_VALUE_REGISTER, |
| 38 | |
| 39 | /* The piece is on the dwarf stack. */ |
| 40 | DWARF_VALUE_STACK, |
| 41 | |
| 42 | /* The piece is a literal. */ |
| 43 | DWARF_VALUE_LITERAL, |
| 44 | |
| 45 | /* The piece was optimized out. */ |
| 46 | DWARF_VALUE_OPTIMIZED_OUT, |
| 47 | |
| 48 | /* The piece is an implicit pointer. */ |
| 49 | DWARF_VALUE_IMPLICIT_POINTER |
| 50 | }; |
| 51 | |
| 52 | /* A piece of an object, as recorded by DW_OP_piece or DW_OP_bit_piece. */ |
| 53 | struct dwarf_expr_piece |
| 54 | { |
| 55 | enum dwarf_value_location location; |
| 56 | |
| 57 | union |
| 58 | { |
| 59 | struct |
| 60 | { |
| 61 | /* This piece's address, for DWARF_VALUE_MEMORY pieces. */ |
| 62 | CORE_ADDR addr; |
| 63 | /* Non-zero if the piece is known to be in memory and on |
| 64 | the program's stack. */ |
| 65 | bool in_stack_memory; |
| 66 | } mem; |
| 67 | |
| 68 | /* The piece's register number, for DWARF_VALUE_REGISTER pieces. */ |
| 69 | int regno; |
| 70 | |
| 71 | /* The piece's literal value, for DWARF_VALUE_STACK pieces. */ |
| 72 | struct value *value; |
| 73 | |
| 74 | struct |
| 75 | { |
| 76 | /* A pointer to the data making up this piece, |
| 77 | for DWARF_VALUE_LITERAL pieces. */ |
| 78 | const gdb_byte *data; |
| 79 | /* The length of the available data. */ |
| 80 | ULONGEST length; |
| 81 | } literal; |
| 82 | |
| 83 | /* Used for DWARF_VALUE_IMPLICIT_POINTER. */ |
| 84 | struct |
| 85 | { |
| 86 | /* The referent DIE from DW_OP_implicit_pointer. */ |
| 87 | sect_offset die_sect_off; |
| 88 | /* The byte offset into the resulting data. */ |
| 89 | LONGEST offset; |
| 90 | } ptr; |
| 91 | } v; |
| 92 | |
| 93 | /* The length of the piece, in bits. */ |
| 94 | ULONGEST size; |
| 95 | /* The piece offset, in bits. */ |
| 96 | ULONGEST offset; |
| 97 | }; |
| 98 | |
| 99 | /* The dwarf expression stack. */ |
| 100 | |
| 101 | struct dwarf_stack_value |
| 102 | { |
| 103 | dwarf_stack_value (struct value *value_, int in_stack_memory_) |
| 104 | : value (value_), in_stack_memory (in_stack_memory_) |
| 105 | {} |
| 106 | |
| 107 | struct value *value; |
| 108 | |
| 109 | /* True if the piece is in memory and is known to be on the program's stack. |
| 110 | It is always ok to set this to zero. This is used, for example, to |
| 111 | optimize memory access from the target. It can vastly speed up backtraces |
| 112 | on long latency connections when "set stack-cache on". */ |
| 113 | bool in_stack_memory; |
| 114 | }; |
| 115 | |
| 116 | /* The expression evaluator works with a dwarf_expr_context, describing |
| 117 | its current state and its callbacks. */ |
| 118 | struct dwarf_expr_context |
| 119 | { |
| 120 | dwarf_expr_context (); |
| 121 | virtual ~dwarf_expr_context () = default; |
| 122 | |
| 123 | void push_address (CORE_ADDR value, bool in_stack_memory); |
| 124 | void eval (const gdb_byte *addr, size_t len); |
| 125 | struct value *fetch (int n); |
| 126 | CORE_ADDR fetch_address (int n); |
| 127 | bool fetch_in_stack_memory (int n); |
| 128 | |
| 129 | /* The stack of values. */ |
| 130 | std::vector<dwarf_stack_value> stack; |
| 131 | |
| 132 | /* Target architecture to use for address operations. */ |
| 133 | struct gdbarch *gdbarch; |
| 134 | |
| 135 | /* Target address size in bytes. */ |
| 136 | int addr_size; |
| 137 | |
| 138 | /* DW_FORM_ref_addr size in bytes. If -1 DWARF is executed from a frame |
| 139 | context and operations depending on DW_FORM_ref_addr are not allowed. */ |
| 140 | int ref_addr_size; |
| 141 | |
| 142 | /* Offset used to relocate DW_OP_addr and DW_OP_GNU_addr_index arguments. */ |
| 143 | CORE_ADDR offset; |
| 144 | |
| 145 | /* The current depth of dwarf expression recursion, via DW_OP_call*, |
| 146 | DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum |
| 147 | depth we'll tolerate before raising an error. */ |
| 148 | int recursion_depth, max_recursion_depth; |
| 149 | |
| 150 | /* Location of the value. */ |
| 151 | enum dwarf_value_location location; |
| 152 | |
| 153 | /* For DWARF_VALUE_LITERAL, the current literal value's length and |
| 154 | data. For DWARF_VALUE_IMPLICIT_POINTER, LEN is the offset of the |
| 155 | target DIE of sect_offset kind. */ |
| 156 | ULONGEST len; |
| 157 | const gdb_byte *data; |
| 158 | |
| 159 | /* Initialization status of variable: Non-zero if variable has been |
| 160 | initialized; zero otherwise. */ |
| 161 | int initialized; |
| 162 | |
| 163 | /* A vector of pieces. |
| 164 | |
| 165 | Each time DW_OP_piece is executed, we add a new element to the |
| 166 | end of this array, recording the current top of the stack, the |
| 167 | current location, and the size given as the operand to |
| 168 | DW_OP_piece. We then pop the top value from the stack, reset the |
| 169 | location, and resume evaluation. |
| 170 | |
| 171 | The Dwarf spec doesn't say whether DW_OP_piece pops the top value |
| 172 | from the stack. We do, ensuring that clients of this interface |
| 173 | expecting to see a value left on the top of the stack (say, code |
| 174 | evaluating frame base expressions or CFA's specified with |
| 175 | DW_CFA_def_cfa_expression) will get an error if the expression |
| 176 | actually marks all the values it computes as pieces. |
| 177 | |
| 178 | If an expression never uses DW_OP_piece, num_pieces will be zero. |
| 179 | (It would be nice to present these cases as expressions yielding |
| 180 | a single piece, so that callers need not distinguish between the |
| 181 | no-DW_OP_piece and one-DW_OP_piece cases. But expressions with |
| 182 | no DW_OP_piece operations have no value to place in a piece's |
| 183 | 'size' field; the size comes from the surrounding data. So the |
| 184 | two cases need to be handled separately.) */ |
| 185 | std::vector<dwarf_expr_piece> pieces; |
| 186 | |
| 187 | /* Return the value of register number REGNUM (a DWARF register number), |
| 188 | read as an address. */ |
| 189 | virtual CORE_ADDR read_addr_from_reg (int regnum) = 0; |
| 190 | |
| 191 | /* Return a value of type TYPE, stored in register number REGNUM |
| 192 | of the frame associated to the given BATON. |
| 193 | |
| 194 | REGNUM is a DWARF register number. */ |
| 195 | virtual struct value *get_reg_value (struct type *type, int regnum) = 0; |
| 196 | |
| 197 | /* Read LENGTH bytes at ADDR into BUF. */ |
| 198 | virtual void read_mem (gdb_byte *buf, CORE_ADDR addr, size_t length) = 0; |
| 199 | |
| 200 | /* Return the location expression for the frame base attribute, in |
| 201 | START and LENGTH. The result must be live until the current |
| 202 | expression evaluation is complete. */ |
| 203 | virtual void get_frame_base (const gdb_byte **start, size_t *length) = 0; |
| 204 | |
| 205 | /* Return the CFA for the frame. */ |
| 206 | virtual CORE_ADDR get_frame_cfa () = 0; |
| 207 | |
| 208 | /* Return the PC for the frame. */ |
| 209 | virtual CORE_ADDR get_frame_pc () |
| 210 | { |
| 211 | error (_("%s is invalid in this context"), "DW_OP_implicit_pointer"); |
| 212 | } |
| 213 | |
| 214 | /* Return the thread-local storage address for |
| 215 | DW_OP_GNU_push_tls_address or DW_OP_form_tls_address. */ |
| 216 | virtual CORE_ADDR get_tls_address (CORE_ADDR offset) = 0; |
| 217 | |
| 218 | /* Execute DW_AT_location expression for the DWARF expression |
| 219 | subroutine in the DIE at DIE_CU_OFF in the CU. Do not touch |
| 220 | STACK while it being passed to and returned from the called DWARF |
| 221 | subroutine. */ |
| 222 | virtual void dwarf_call (cu_offset die_cu_off) = 0; |
| 223 | |
| 224 | /* Execute "variable value" operation on the DIE at SECT_OFF. */ |
| 225 | virtual struct value *dwarf_variable_value (sect_offset sect_off) = 0; |
| 226 | |
| 227 | /* Return the base type given by the indicated DIE at DIE_CU_OFF. |
| 228 | This can throw an exception if the DIE is invalid or does not |
| 229 | represent a base type. SIZE is non-zero if this function should |
| 230 | verify that the resulting type has the correct size. */ |
| 231 | virtual struct type *get_base_type (cu_offset die_cu_off, int size) |
| 232 | { |
| 233 | /* Anything will do. */ |
| 234 | return builtin_type (this->gdbarch)->builtin_int; |
| 235 | } |
| 236 | |
| 237 | /* Push on DWARF stack an entry evaluated for DW_TAG_call_site's |
| 238 | parameter matching KIND and KIND_U at the caller of specified BATON. |
| 239 | If DEREF_SIZE is not -1 then use DW_AT_call_data_value instead of |
| 240 | DW_AT_call_value. */ |
| 241 | virtual void push_dwarf_reg_entry_value (enum call_site_parameter_kind kind, |
| 242 | union call_site_parameter_u kind_u, |
| 243 | int deref_size) = 0; |
| 244 | |
| 245 | /* Return the address indexed by DW_OP_GNU_addr_index. |
| 246 | This can throw an exception if the index is out of range. */ |
| 247 | virtual CORE_ADDR get_addr_index (unsigned int index) = 0; |
| 248 | |
| 249 | /* Return the `object address' for DW_OP_push_object_address. */ |
| 250 | virtual CORE_ADDR get_object_address () = 0; |
| 251 | |
| 252 | private: |
| 253 | |
| 254 | struct type *address_type () const; |
| 255 | void push (struct value *value, bool in_stack_memory); |
| 256 | bool stack_empty_p () const; |
| 257 | void add_piece (ULONGEST size, ULONGEST offset); |
| 258 | void execute_stack_op (const gdb_byte *op_ptr, const gdb_byte *op_end); |
| 259 | void pop (); |
| 260 | }; |
| 261 | |
| 262 | void dwarf_expr_require_composition (const gdb_byte *, const gdb_byte *, |
| 263 | const char *); |
| 264 | |
| 265 | int dwarf_block_to_dwarf_reg (const gdb_byte *buf, const gdb_byte *buf_end); |
| 266 | |
| 267 | int dwarf_block_to_dwarf_reg_deref (const gdb_byte *buf, |
| 268 | const gdb_byte *buf_end, |
| 269 | CORE_ADDR *deref_size_return); |
| 270 | |
| 271 | int dwarf_block_to_fb_offset (const gdb_byte *buf, const gdb_byte *buf_end, |
| 272 | CORE_ADDR *fb_offset_return); |
| 273 | |
| 274 | int dwarf_block_to_sp_offset (struct gdbarch *gdbarch, const gdb_byte *buf, |
| 275 | const gdb_byte *buf_end, |
| 276 | CORE_ADDR *sp_offset_return); |
| 277 | |
| 278 | /* Wrappers around the leb128 reader routines to simplify them for our |
| 279 | purposes. */ |
| 280 | |
| 281 | static inline const gdb_byte * |
| 282 | gdb_read_uleb128 (const gdb_byte *buf, const gdb_byte *buf_end, |
| 283 | uint64_t *r) |
| 284 | { |
| 285 | size_t bytes_read = read_uleb128_to_uint64 (buf, buf_end, r); |
| 286 | |
| 287 | if (bytes_read == 0) |
| 288 | return NULL; |
| 289 | return buf + bytes_read; |
| 290 | } |
| 291 | |
| 292 | static inline const gdb_byte * |
| 293 | gdb_read_sleb128 (const gdb_byte *buf, const gdb_byte *buf_end, |
| 294 | int64_t *r) |
| 295 | { |
| 296 | size_t bytes_read = read_sleb128_to_int64 (buf, buf_end, r); |
| 297 | |
| 298 | if (bytes_read == 0) |
| 299 | return NULL; |
| 300 | return buf + bytes_read; |
| 301 | } |
| 302 | |
| 303 | static inline const gdb_byte * |
| 304 | gdb_skip_leb128 (const gdb_byte *buf, const gdb_byte *buf_end) |
| 305 | { |
| 306 | size_t bytes_read = skip_leb128 (buf, buf_end); |
| 307 | |
| 308 | if (bytes_read == 0) |
| 309 | return NULL; |
| 310 | return buf + bytes_read; |
| 311 | } |
| 312 | |
| 313 | extern const gdb_byte *safe_read_uleb128 (const gdb_byte *buf, |
| 314 | const gdb_byte *buf_end, |
| 315 | uint64_t *r); |
| 316 | |
| 317 | extern const gdb_byte *safe_read_sleb128 (const gdb_byte *buf, |
| 318 | const gdb_byte *buf_end, |
| 319 | int64_t *r); |
| 320 | |
| 321 | extern const gdb_byte *safe_skip_leb128 (const gdb_byte *buf, |
| 322 | const gdb_byte *buf_end); |
| 323 | |
| 324 | #endif /* dwarf2expr.h */ |