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1 /* DWARF 2 Expression Evaluator.
2 
3  Copyright (C) 2001-2015 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 struct dwarf_expr_context;
29 
30 /* Virtual method table for struct dwarf_expr_context below. */
31 
33 {
34  /* Return the value of register number REGNUM (a DWARF register number),
35  read as an address. */
36  CORE_ADDR (*read_addr_from_reg) (void *baton, int regnum);
37 
38  /* Return a value of type TYPE, stored in register number REGNUM
39  of the frame associated to the given BATON.
40 
41  REGNUM is a DWARF register number. */
42  struct value *(*get_reg_value) (void *baton, struct type *type, int regnum);
43 
44  /* Read LENGTH bytes at ADDR into BUF. */
45  void (*read_mem) (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t length);
46 
47  /* Return the location expression for the frame base attribute, in
48  START and LENGTH. The result must be live until the current
49  expression evaluation is complete. */
50  void (*get_frame_base) (void *baton, const gdb_byte **start, size_t *length);
51 
52  /* Return the CFA for the frame. */
53  CORE_ADDR (*get_frame_cfa) (void *baton);
54 
55  /* Return the PC for the frame. */
56  CORE_ADDR (*get_frame_pc) (void *baton);
57 
58  /* Return the thread-local storage address for
59  DW_OP_GNU_push_tls_address. */
61 
62  /* Execute DW_AT_location expression for the DWARF expression subroutine in
63  the DIE at DIE_OFFSET in the CU from CTX. Do not touch STACK while it
64  being passed to and returned from the called DWARF subroutine. */
65  void (*dwarf_call) (struct dwarf_expr_context *ctx, cu_offset die_offset);
66 
67  /* Return the base type given by the indicated DIE. This can throw
68  an exception if the DIE is invalid or does not represent a base
69  type. If can also be NULL in the special case where the
70  callbacks are not performing evaluation, and thus it is
71  meaningful to substitute a stub type of the correct size. */
72  struct type *(*get_base_type) (struct dwarf_expr_context *ctx, cu_offset die);
73 
74  /* Push on DWARF stack an entry evaluated for DW_TAG_GNU_call_site's
75  parameter matching KIND and KIND_U at the caller of specified BATON.
76  If DEREF_SIZE is not -1 then use DW_AT_GNU_call_site_data_value instead of
77  DW_AT_GNU_call_site_value. */
79  enum call_site_parameter_kind kind,
80  union call_site_parameter_u kind_u,
81  int deref_size);
82 
83  /* Return the address indexed by DW_OP_GNU_addr_index.
84  This can throw an exception if the index is out of range. */
85  CORE_ADDR (*get_addr_index) (void *baton, unsigned int index);
86 
87  /* Return the `object address' for DW_OP_push_object_address. */
88  CORE_ADDR (*get_object_address) (void *baton);
89 };
90 
91 /* The location of a value. */
93 {
94  /* The piece is in memory.
95  The value on the dwarf stack is its address. */
97 
98  /* The piece is in a register.
99  The value on the dwarf stack is the register number. */
101 
102  /* The piece is on the dwarf stack. */
104 
105  /* The piece is a literal. */
107 
108  /* The piece was optimized out. */
110 
111  /* The piece is an implicit pointer. */
113 };
114 
115 /* The dwarf expression stack. */
116 
118 {
119  struct value *value;
120 
121  /* Non-zero if the piece is in memory and is known to be
122  on the program's stack. It is always ok to set this to zero.
123  This is used, for example, to optimize memory access from the target.
124  It can vastly speed up backtraces on long latency connections when
125  "set stack-cache on". */
127 };
128 
129 /* The expression evaluator works with a dwarf_expr_context, describing
130  its current state and its callbacks. */
132 {
133  /* The stack of values, allocated with xmalloc. */
135 
136  /* The number of values currently pushed on the stack, and the
137  number of elements allocated to the stack. */
139 
140  /* Target architecture to use for address operations. */
141  struct gdbarch *gdbarch;
142 
143  /* Target address size in bytes. */
145 
146  /* DW_FORM_ref_addr size in bytes. If -1 DWARF is executed from a frame
147  context and operations depending on DW_FORM_ref_addr are not allowed. */
149 
150  /* Offset used to relocate DW_OP_addr and DW_OP_GNU_addr_index arguments. */
152 
153  /* An opaque argument provided by the caller, which will be passed
154  to all of the callback functions. */
155  void *baton;
156 
157  /* Callback functions. */
159 
160  /* The current depth of dwarf expression recursion, via DW_OP_call*,
161  DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum
162  depth we'll tolerate before raising an error. */
164 
165  /* Location of the value. */
167 
168  /* For DWARF_VALUE_LITERAL, the current literal value's length and
169  data. For DWARF_VALUE_IMPLICIT_POINTER, LEN is the offset of the
170  target DIE of sect_offset kind. */
172  const gdb_byte *data;
173 
174  /* Initialization status of variable: Non-zero if variable has been
175  initialized; zero otherwise. */
177 
178  /* An array of pieces. PIECES points to its first element;
179  NUM_PIECES is its length.
180 
181  Each time DW_OP_piece is executed, we add a new element to the
182  end of this array, recording the current top of the stack, the
183  current location, and the size given as the operand to
184  DW_OP_piece. We then pop the top value from the stack, reset the
185  location, and resume evaluation.
186 
187  The Dwarf spec doesn't say whether DW_OP_piece pops the top value
188  from the stack. We do, ensuring that clients of this interface
189  expecting to see a value left on the top of the stack (say, code
190  evaluating frame base expressions or CFA's specified with
191  DW_CFA_def_cfa_expression) will get an error if the expression
192  actually marks all the values it computes as pieces.
193 
194  If an expression never uses DW_OP_piece, num_pieces will be zero.
195  (It would be nice to present these cases as expressions yielding
196  a single piece, so that callers need not distinguish between the
197  no-DW_OP_piece and one-DW_OP_piece cases. But expressions with
198  no DW_OP_piece operations have no value to place in a piece's
199  'size' field; the size comes from the surrounding data. So the
200  two cases need to be handled separately.) */
203 };
204 
205 
206 /* A piece of an object, as recorded by DW_OP_piece or DW_OP_bit_piece. */
208 {
210 
211  union
212  {
213  struct
214  {
215  /* This piece's address, for DWARF_VALUE_MEMORY pieces. */
217  /* Non-zero if the piece is known to be in memory and on
218  the program's stack. */
220  } mem;
221 
222  /* The piece's register number, for DWARF_VALUE_REGISTER pieces. */
223  int regno;
224 
225  /* The piece's literal value, for DWARF_VALUE_STACK pieces. */
226  struct value *value;
227 
228  struct
229  {
230  /* A pointer to the data making up this piece,
231  for DWARF_VALUE_LITERAL pieces. */
232  const gdb_byte *data;
233  /* The length of the available data. */
235  } literal;
236 
237  /* Used for DWARF_VALUE_IMPLICIT_POINTER. */
238  struct
239  {
240  /* The referent DIE from DW_OP_GNU_implicit_pointer. */
242  /* The byte offset into the resulting data. */
244  } ptr;
245  } v;
246 
247  /* The length of the piece, in bits. */
249  /* The piece offset, in bits. */
251 };
252 
255 struct cleanup *
257 
260  int in_stack_memory);
261 void dwarf_expr_eval (struct dwarf_expr_context *ctx, const gdb_byte *addr,
262  size_t len);
263 struct value *dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n);
266 
267 void dwarf_expr_require_composition (const gdb_byte *, const gdb_byte *,
268  const char *);
269 
270 /* Stub dwarf_expr_context_funcs implementations. */
271 
272 void ctx_no_get_frame_base (void *baton, const gdb_byte **start,
273  size_t *length);
274 CORE_ADDR ctx_no_get_frame_cfa (void *baton);
275 CORE_ADDR ctx_no_get_frame_pc (void *baton);
277 void ctx_no_dwarf_call (struct dwarf_expr_context *ctx, cu_offset die_offset);
278 struct type *ctx_no_get_base_type (struct dwarf_expr_context *ctx,
279  cu_offset die);
281  enum call_site_parameter_kind kind,
282  union call_site_parameter_u kind_u,
283  int deref_size);
284 CORE_ADDR ctx_no_get_addr_index (void *baton, unsigned int index);
285 
286 int dwarf_block_to_dwarf_reg (const gdb_byte *buf, const gdb_byte *buf_end);
287 
289  const gdb_byte *buf_end,
290  CORE_ADDR *deref_size_return);
291 
292 int dwarf_block_to_fb_offset (const gdb_byte *buf, const gdb_byte *buf_end,
293  CORE_ADDR *fb_offset_return);
294 
295 int dwarf_block_to_sp_offset (struct gdbarch *gdbarch, const gdb_byte *buf,
296  const gdb_byte *buf_end,
297  CORE_ADDR *sp_offset_return);
298 
299 /* Wrappers around the leb128 reader routines to simplify them for our
300  purposes. */
301 
302 static inline const gdb_byte *
303 gdb_read_uleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
304  uint64_t *r)
305 {
306  size_t bytes_read = read_uleb128_to_uint64 (buf, buf_end, r);
307 
308  if (bytes_read == 0)
309  return NULL;
310  return buf + bytes_read;
311 }
312 
313 static inline const gdb_byte *
314 gdb_read_sleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
315  int64_t *r)
316 {
317  size_t bytes_read = read_sleb128_to_int64 (buf, buf_end, r);
318 
319  if (bytes_read == 0)
320  return NULL;
321  return buf + bytes_read;
322 }
323 
324 static inline const gdb_byte *
325 gdb_skip_leb128 (const gdb_byte *buf, const gdb_byte *buf_end)
326 {
327  size_t bytes_read = skip_leb128 (buf, buf_end);
328 
329  if (bytes_read == 0)
330  return NULL;
331  return buf + bytes_read;
332 }
333 
334 extern const gdb_byte *safe_read_uleb128 (const gdb_byte *buf,
335  const gdb_byte *buf_end,
336  uint64_t *r);
337 
338 extern const gdb_byte *safe_read_sleb128 (const gdb_byte *buf,
339  const gdb_byte *buf_end,
340  int64_t *r);
341 
342 extern const gdb_byte *safe_skip_leb128 (const gdb_byte *buf,
343  const gdb_byte *buf_end);
344 
345 #endif /* dwarf2expr.h */
const gdb_byte * safe_read_uleb128(const gdb_byte *buf, const gdb_byte *buf_end, uint64_t *r)
Definition: dwarf2expr.c:373
dwarf_value_location
Definition: dwarf2expr.h:92
CORE_ADDR addr
Definition: dwarf2expr.h:216
void dwarf_expr_push_address(struct dwarf_expr_context *ctx, CORE_ADDR value, int in_stack_memory)
Definition: dwarf2expr.c:167
bfd_vma CORE_ADDR
Definition: common-types.h:41
CORE_ADDR ctx_no_get_tls_address(void *baton, CORE_ADDR offset)
Definition: dwarf2expr.c:1535
void dwarf_expr_eval(struct dwarf_expr_context *ctx, const gdb_byte *addr, size_t len)
Definition: dwarf2expr.c:358
struct dwarf_expr_piece::@52::@55 ptr
void free_dwarf_expr_context(struct dwarf_expr_context *ctx)
Definition: dwarf2expr.c:111
struct gdbarch * gdbarch
Definition: dwarf2expr.h:141
void dwarf_expr_require_composition(const gdb_byte *, const gdb_byte *, const char *)
Definition: dwarf2expr.c:408
CORE_ADDR(* get_addr_index)(void *baton, unsigned int index)
Definition: dwarf2expr.h:85
static const gdb_byte * gdb_skip_leb128(const gdb_byte *buf, const gdb_byte *buf_end)
Definition: dwarf2expr.h:325
ULONGEST length
Definition: dwarf2expr.h:234
CORE_ADDR dwarf_expr_fetch_address(struct dwarf_expr_context *ctx, int n)
Definition: dwarf2expr.c:255
CORE_ADDR ctx_no_get_frame_cfa(void *baton)
Definition: dwarf2expr.c:1519
int dwarf_expr_fetch_in_stack_memory(struct dwarf_expr_context *ctx, int n)
Definition: dwarf2expr.c:288
void ctx_no_push_dwarf_reg_entry_value(struct dwarf_expr_context *ctx, enum call_site_parameter_kind kind, union call_site_parameter_u kind_u, int deref_size)
Definition: dwarf2expr.c:1560
CORE_ADDR(* get_object_address)(void *baton)
Definition: dwarf2expr.h:88
ULONGEST offset
Definition: dwarf2expr.h:250
CORE_ADDR(* get_tls_address)(void *baton, CORE_ADDR offset)
Definition: dwarf2expr.h:60
struct dwarf_expr_piece::@52::@53 mem
struct dwarf_expr_context * new_dwarf_expr_context(void)
Definition: dwarf2expr.c:93
const struct dwarf_expr_context_funcs * funcs
Definition: dwarf2expr.h:158
const gdb_byte * safe_skip_leb128(const gdb_byte *buf, const gdb_byte *buf_end)
Definition: dwarf2expr.c:395
call_site_parameter_kind
Definition: gdbtypes.h:1092
int dwarf_block_to_sp_offset(struct gdbarch *gdbarch, const gdb_byte *buf, const gdb_byte *buf_end, CORE_ADDR *sp_offset_return)
Definition: dwarf2expr.c:593
const gdb_byte * safe_read_sleb128(const gdb_byte *buf, const gdb_byte *buf_end, int64_t *r)
Definition: dwarf2expr.c:385
Definition: gdbtypes.h:749
CORE_ADDR ctx_no_get_frame_pc(void *baton)
Definition: dwarf2expr.c:1527
CORE_ADDR(* get_frame_pc)(void *baton)
Definition: dwarf2expr.h:56
static const gdb_byte * gdb_read_uleb128(const gdb_byte *buf, const gdb_byte *buf_end, uint64_t *r)
Definition: dwarf2expr.h:303
sect_offset die
Definition: dwarf2expr.h:241
static const char * type
Definition: language.c:103
CORE_ADDR ctx_no_get_addr_index(void *baton, unsigned int index)
Definition: dwarf2expr.c:1572
struct dwarf_expr_piece::@52::@54 literal
int regnum
Definition: aarch64-tdep.c:69
int dwarf_block_to_dwarf_reg_deref(const gdb_byte *buf, const gdb_byte *buf_end, CORE_ADDR *deref_size_return)
Definition: dwarf2expr.c:507
void ctx_no_dwarf_call(struct dwarf_expr_context *ctx, cu_offset die_offset)
Definition: dwarf2expr.c:1543
enum dwarf_value_location location
Definition: dwarf2expr.h:209
struct dwarf_expr_piece * pieces
Definition: dwarf2expr.h:202
Definition: value.c:172
int dwarf_block_to_fb_offset(const gdb_byte *buf, const gdb_byte *buf_end, CORE_ADDR *fb_offset_return)
Definition: dwarf2expr.c:566
const char const char int
Definition: command.h:229
bfd_byte gdb_byte
Definition: common-types.h:38
unsigned length
Definition: gdbtypes.h:807
CORE_ADDR(* get_frame_cfa)(void *baton)
Definition: dwarf2expr.h:53
struct type * ctx_no_get_base_type(struct dwarf_expr_context *ctx, cu_offset die)
Definition: dwarf2expr.c:1551
const gdb_byte * data
Definition: dwarf2expr.h:172
struct value * value
Definition: dwarf2expr.h:119
void(* dwarf_call)(struct dwarf_expr_context *ctx, cu_offset die_offset)
Definition: dwarf2expr.h:65
int offset
Definition: agent.c:65
CORE_ADDR offset
Definition: dwarf2expr.h:151
CORE_ADDR(* read_addr_from_reg)(void *baton, int regnum)
Definition: dwarf2expr.h:36
void ctx_no_get_frame_base(void *baton, const gdb_byte **start, size_t *length)
Definition: dwarf2expr.c:1511
struct value * dwarf_expr_fetch(struct dwarf_expr_context *ctx, int n)
Definition: dwarf2expr.c:188
void(* get_frame_base)(void *baton, const gdb_byte **start, size_t *length)
Definition: dwarf2expr.h:50
enum dwarf_value_location location
Definition: dwarf2expr.h:166
unsigned long long ULONGEST
Definition: common-types.h:53
struct dwarf_stack_value * stack
Definition: dwarf2expr.h:134
static const gdb_byte * gdb_read_sleb128(const gdb_byte *buf, const gdb_byte *buf_end, int64_t *r)
Definition: dwarf2expr.h:314
union dwarf_expr_piece::@52 v
void(* push_dwarf_reg_entry_value)(struct dwarf_expr_context *ctx, enum call_site_parameter_kind kind, union call_site_parameter_u kind_u, int deref_size)
Definition: dwarf2expr.h:78
const gdb_byte * data
Definition: dwarf2expr.h:232
struct cleanup * make_cleanup_free_dwarf_expr_context(struct dwarf_expr_context *ctx)
Definition: dwarf2expr.c:129
struct value * value
Definition: dwarf2expr.h:226
long long LONGEST
Definition: common-types.h:52
int dwarf_block_to_dwarf_reg(const gdb_byte *buf, const gdb_byte *buf_end)
Definition: dwarf2expr.c:464
const ULONGEST const LONGEST len
Definition: target.h:309
void(* read_mem)(void *baton, gdb_byte *buf, CORE_ADDR addr, size_t length)
Definition: dwarf2expr.h:45