1 /* Definitions for a frame unwinder, for GDB, the GNU debugger. 2 3 Copyright (C) 2003-2013 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 223