| 1 | /* Definitions for a frame unwinder, for GDB, the GNU debugger. |
| 2 | |
| 3 | Copyright (C) 2003-2016 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 | |
| 55 | typedef enum unwind_stop_reason (frame_unwind_stop_reason_ftype) |
| 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 | |
| 68 | enum unwind_stop_reason |
| 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 | |
| 143 | struct frame_unwind |
| 144 | { |
| 145 | /* The frame's type. Should this instead be a collection of |
| 146 | predicates that test the frame for various attributes? */ |
| 147 | enum frame_type type; |
| 148 | /* Should an attribute indicating the frame's address-in-block go |
| 149 | here? */ |
| 150 | frame_unwind_stop_reason_ftype *stop_reason; |
| 151 | frame_this_id_ftype *this_id; |
| 152 | frame_prev_register_ftype *prev_register; |
| 153 | const struct frame_data *unwind_data; |
| 154 | frame_sniffer_ftype *sniffer; |
| 155 | frame_dealloc_cache_ftype *dealloc_cache; |
| 156 | frame_prev_arch_ftype *prev_arch; |
| 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 |