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1 /* Definitions for a frame unwinder, for GDB, the GNU debugger.
2 
3  Copyright (C) 2003-2015 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 #if !defined (FRAME_UNWIND_H)
21 #define FRAME_UNWIND_H 1
22 
23 struct frame_data;
24 struct frame_info;
25 struct frame_id;
26 struct frame_unwind;
27 struct gdbarch;
28 struct regcache;
29 struct value;
30 
31 #include "frame.h" /* For enum frame_type. */
32 
33 /* The following unwind functions assume a chain of frames forming the
34  sequence: (outer) prev <-> this <-> next (inner). All the
35  functions are called with this frame's `struct frame_info' and
36  prologue cache.
37 
38  THIS frame's register values can be obtained by unwinding NEXT
39  frame's registers (a recursive operation).
40 
41  THIS frame's prologue cache can be used to cache information such
42  as where this frame's prologue stores the previous frame's
43  registers. */
44 
45 /* Given THIS frame, take a whiff of its registers (namely
46  the PC and attributes) and if SELF is the applicable unwinder,
47  return non-zero. Possibly also initialize THIS_PROLOGUE_CACHE; but
48  only if returning 1. Initializing THIS_PROLOGUE_CACHE in other
49  cases (0 return, or exception) is invalid. */
50 
51 typedef int (frame_sniffer_ftype) (const struct frame_unwind *self,
52  struct frame_info *this_frame,
53  void **this_prologue_cache);
54 
56  (struct frame_info *this_frame, void **this_prologue_cache);
57 
58 /* A default frame sniffer which always accepts the frame. Used by
59  fallback prologue unwinders. */
60 
61 int default_frame_sniffer (const struct frame_unwind *self,
62  struct frame_info *this_frame,
63  void **this_prologue_cache);
64 
65 /* A default stop_reason callback which always claims the frame is
66  unwindable. */
67 
69  default_frame_unwind_stop_reason (struct frame_info *this_frame,
70  void **this_cache);
71 
72 /* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
73  use THIS frame, and through it the NEXT frame's register unwind
74  method, to determine the frame ID of THIS frame.
75 
76  A frame ID provides an invariant that can be used to re-identify an
77  instance of a frame. It is a combination of the frame's `base' and
78  the frame's function's code address.
79 
80  Traditionally, THIS frame's ID was determined by examining THIS
81  frame's function's prologue, and identifying the register/offset
82  used as THIS frame's base.
83 
84  Example: An examination of THIS frame's prologue reveals that, on
85  entry, it saves the PC(+12), SP(+8), and R1(+4) registers
86  (decrementing the SP by 12). Consequently, the frame ID's base can
87  be determined by adding 12 to the THIS frame's stack-pointer, and
88  the value of THIS frame's SP can be obtained by unwinding the NEXT
89  frame's SP.
90 
91  THIS_PROLOGUE_CACHE can be used to share any prolog analysis data
92  with the other unwind methods. Memory for that cache should be
93  allocated using FRAME_OBSTACK_ZALLOC(). */
94 
95 typedef void (frame_this_id_ftype) (struct frame_info *this_frame,
96  void **this_prologue_cache,
97  struct frame_id *this_id);
98 
99 /* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
100  use THIS frame, and implicitly the NEXT frame's register unwind
101  method, to unwind THIS frame's registers (returning the value of
102  the specified register REGNUM in the previous frame).
103 
104  Traditionally, THIS frame's registers were unwound by examining
105  THIS frame's function's prologue and identifying which registers
106  that prolog code saved on the stack.
107 
108  Example: An examination of THIS frame's prologue reveals that, on
109  entry, it saves the PC(+12), SP(+8), and R1(+4) registers
110  (decrementing the SP by 12). Consequently, the value of the PC
111  register in the previous frame is found in memory at SP+12, and
112  THIS frame's SP can be obtained by unwinding the NEXT frame's SP.
113 
114  This function takes THIS_FRAME as an argument. It can find the
115  values of registers in THIS frame by calling get_frame_register
116  (THIS_FRAME), and reinvoke itself to find other registers in the
117  PREVIOUS frame by calling frame_unwind_register (THIS_FRAME).
118 
119  The result is a GDB value object describing the register value. It
120  may be a lazy reference to memory, a lazy reference to the value of
121  a register in THIS frame, or a non-lvalue.
122 
123  THIS_PROLOGUE_CACHE can be used to share any prolog analysis data
124  with the other unwind methods. Memory for that cache should be
125  allocated using FRAME_OBSTACK_ZALLOC(). */
126 
127 typedef struct value * (frame_prev_register_ftype)
128  (struct frame_info *this_frame, void **this_prologue_cache,
129  int regnum);
130 
131 /* Deallocate extra memory associated with the frame cache if any. */
132 
133 typedef void (frame_dealloc_cache_ftype) (struct frame_info *self,
134  void *this_cache);
135 
136 /* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
137  use THIS frame, and implicitly the NEXT frame's register unwind
138  method, return PREV frame's architecture. */
139 
140 typedef struct gdbarch *(frame_prev_arch_ftype) (struct frame_info *this_frame,
141  void **this_prologue_cache);
142 
144 {
145  /* The frame's type. Should this instead be a collection of
146  predicates that test the frame for various attributes? */
148  /* Should an attribute indicating the frame's address-in-block go
149  here? */
153  const struct frame_data *unwind_data;
157 };
158 
159 /* Register a frame unwinder, _prepending_ it to the front of the
160  search list (so it is sniffed before previously registered
161  unwinders). By using a prepend, later calls can install unwinders
162  that override earlier calls. This allows, for instance, an OSABI
163  to install a more specific sigtramp unwinder that overrides the
164  traditional brute-force unwinder. */
165 extern void frame_unwind_prepend_unwinder (struct gdbarch *,
166  const struct frame_unwind *);
167 
168 /* Add a frame sniffer to the list. The predicates are polled in the
169  order that they are appended. The initial list contains the dummy
170  frame sniffer. */
171 
172 extern void frame_unwind_append_unwinder (struct gdbarch *gdbarch,
173  const struct frame_unwind *unwinder);
174 
175 /* Iterate through sniffers for THIS_FRAME frame until one returns with an
176  unwinder implementation. THIS_FRAME->UNWIND must be NULL, it will get set
177  by this function. Possibly initialize THIS_CACHE. */
178 
179 extern void frame_unwind_find_by_frame (struct frame_info *this_frame,
180  void **this_cache);
181 
182 /* Helper functions for value-based register unwinding. These return
183  a (possibly lazy) value of the appropriate type. */
184 
185 /* Return a value which indicates that FRAME did not save REGNUM. */
186 
187 struct value *frame_unwind_got_optimized (struct frame_info *frame,
188  int regnum);
189 
190 /* Return a value which indicates that FRAME copied REGNUM into
191  register NEW_REGNUM. */
192 
193 struct value *frame_unwind_got_register (struct frame_info *frame, int regnum,
194  int new_regnum);
195 
196 /* Return a value which indicates that FRAME saved REGNUM in memory at
197  ADDR. */
198 
199 struct value *frame_unwind_got_memory (struct frame_info *frame, int regnum,
200  CORE_ADDR addr);
201 
202 /* Return a value which indicates that FRAME's saved version of
203  REGNUM has a known constant (computed) value of VAL. */
204 
205 struct value *frame_unwind_got_constant (struct frame_info *frame, int regnum,
206  ULONGEST val);
207 
208 /* Return a value which indicates that FRAME's saved version of
209  REGNUM has a known constant (computed) value which is stored
210  inside BUF. */
211 
212 struct value *frame_unwind_got_bytes (struct frame_info *frame, int regnum,
213  gdb_byte *buf);
214 
215 /* Return a value which indicates that FRAME's saved version of REGNUM
216  has a known constant (computed) value of ADDR. Convert the
217  CORE_ADDR to a target address if necessary. */
218 
219 struct value *frame_unwind_got_address (struct frame_info *frame, int regnum,
220  CORE_ADDR addr);
221 
222 #endif
bfd_vma CORE_ADDR
Definition: common-types.h:41
enum frame_type type
Definition: frame-unwind.h:147
struct value * frame_unwind_got_bytes(struct frame_info *frame, int regnum, gdb_byte *buf)
Definition: frame-unwind.c:255
struct value * frame_unwind_got_constant(struct frame_info *frame, int regnum, ULONGEST val)
Definition: frame-unwind.c:241
frame_prev_register_ftype * prev_register
Definition: frame-unwind.h:152
frame_sniffer_ftype * sniffer
Definition: frame-unwind.h:154
unwind_stop_reason
Definition: frame.h:486
frame_dealloc_cache_ftype * dealloc_cache
Definition: frame-unwind.h:155
void frame_unwind_append_unwinder(struct gdbarch *gdbarch, const struct frame_unwind *unwinder)
Definition: frame-unwind.c:78
struct value * frame_unwind_got_memory(struct frame_info *frame, int regnum, CORE_ADDR addr)
Definition: frame-unwind.c:228
void( frame_this_id_ftype)(struct frame_info *this_frame, void **this_prologue_cache, struct frame_id *this_id)
Definition: frame-unwind.h:95
struct gdbarch *( frame_prev_arch_ftype)(struct frame_info *this_frame, void **this_prologue_cache)
Definition: frame-unwind.h:140
int default_frame_sniffer(const struct frame_unwind *self, struct frame_info *this_frame, void **this_prologue_cache)
Definition: frame-unwind.c:170
enum unwind_stop_reason default_frame_unwind_stop_reason(struct frame_info *this_frame, void **this_cache)
Definition: frame-unwind.c:180
struct value * frame_unwind_got_address(struct frame_info *frame, int regnum, CORE_ADDR addr)
Definition: frame-unwind.c:270
struct value * frame_unwind_got_optimized(struct frame_info *frame, int regnum)
Definition: frame-unwind.c:197
frame_type
Definition: frame.h:231
frame_prev_arch_ftype * prev_arch
Definition: frame-unwind.h:156
frame_unwind_stop_reason_ftype * stop_reason
Definition: frame-unwind.h:150
void frame_unwind_find_by_frame(struct frame_info *this_frame, void **this_cache)
Definition: frame-unwind.c:140
void frame_unwind_prepend_unwinder(struct gdbarch *, const struct frame_unwind *)
Definition: frame-unwind.c:64
int( frame_sniffer_ftype)(const struct frame_unwind *self, struct frame_info *this_frame, void **this_prologue_cache)
Definition: frame-unwind.h:51
void( frame_dealloc_cache_ftype)(struct frame_info *self, void *this_cache)
Definition: frame-unwind.h:133
Definition: value.c:172
const char const char int
Definition: command.h:229
bfd_byte gdb_byte
Definition: common-types.h:38
enum unwind_stop_reason() frame_unwind_stop_reason_ftype(struct frame_info *this_frame, void **this_prologue_cache)
struct value * frame_unwind_got_register(struct frame_info *frame, int regnum, int new_regnum)
Definition: frame-unwind.c:218
unsigned long long ULONGEST
Definition: common-types.h:53
frame_this_id_ftype * this_id
Definition: frame-unwind.h:151
const struct frame_data * unwind_data
Definition: frame-unwind.h:153
struct value *( frame_prev_register_ftype)(struct frame_info *this_frame, void **this_prologue_cache, int regnum)
Definition: frame-unwind.h:128