1 /* Definitions for a frame unwinder, for GDB, the GNU debugger. 2 3 Copyright (C) 2003-2004, 2007-2012 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. */ 48 49 typedef int (frame_sniffer_ftype) (const struct frame_unwind *self, 50 struct frame_info *this_frame, 51 void **this_prologue_cache); 52 53 typedef enum unwind_stop_reason (frame_unwind_stop_reason_ftype) 54 (struct frame_info *this_frame, void **this_prologue_cache); 55 56 /* A default frame sniffer which always accepts the frame. Used by 57 fallback prologue unwinders. */ 58 59 int default_frame_sniffer (const struct frame_unwind *self, 60 struct frame_info *this_frame, 61 void **this_prologue_cache); 62 63 /* A default stop_reason callback which always claims the frame is 64 unwindable. */ 65 66 enum unwind_stop_reason 67 default_frame_unwind_stop_reason (struct frame_info *this_frame, 68 void **this_cache); 69 70 /* Assuming the frame chain: (outer) prev <-> this <-> next (inner); 71 use THIS frame, and through it the NEXT frame's register unwind 72 method, to determine the frame ID of THIS frame. 73 74 A frame ID provides an invariant that can be used to re-identify an 75 instance of a frame. It is a combination of the frame's `base' and 76 the frame's function's code address. 77 78 Traditionally, THIS frame's ID was determined by examining THIS 79 frame's function's prologue, and identifying the register/offset 80 used as THIS frame's base. 81 82 Example: An examination of THIS frame's prologue reveals that, on 83 entry, it saves the PC(+12), SP(+8), and R1(+4) registers 84 (decrementing the SP by 12). Consequently, the frame ID's base can 85 be determined by adding 12 to the THIS frame's stack-pointer, and 86 the value of THIS frame's SP can be obtained by unwinding the NEXT 87 frame's SP. 88 89 THIS_PROLOGUE_CACHE can be used to share any prolog analysis data 90 with the other unwind methods. Memory for that cache should be 91 allocated using FRAME_OBSTACK_ZALLOC(). */ 92 93 typedef void (frame_this_id_ftype) (struct frame_info *this_frame, 94 void **this_prologue_cache, 95 struct frame_id *this_id); 96 97 /* Assuming the frame chain: (outer) prev <-> this <-> next (inner); 98 use THIS frame, and implicitly the NEXT frame's register unwind 99 method, to unwind THIS frame's registers (returning the value of 100 the specified register REGNUM in the previous frame). 101 102 Traditionally, THIS frame's registers were unwound by examining 103 THIS frame's function's prologue and identifying which registers 104 that prolog code saved on the stack. 105 106 Example: An examination of THIS frame's prologue reveals that, on 107 entry, it saves the PC(+12), SP(+8), and R1(+4) registers 108 (decrementing the SP by 12). Consequently, the value of the PC 109 register in the previous frame is found in memory at SP+12, and 110 THIS frame's SP can be obtained by unwinding the NEXT frame's SP. 111 112 This function takes THIS_FRAME as an argument. It can find the 113 values of registers in THIS frame by calling get_frame_register 114 (THIS_FRAME), and reinvoke itself to find other registers in the 115 PREVIOUS frame by calling frame_unwind_register (THIS_FRAME). 116 117 The result is a GDB value object describing the register value. It 118 may be a lazy reference to memory, a lazy reference to the value of 119 a register in THIS frame, or a non-lvalue. 120 121 THIS_PROLOGUE_CACHE can be used to share any prolog analysis data 122 with the other unwind methods. Memory for that cache should be 123 allocated using FRAME_OBSTACK_ZALLOC(). */ 124 125 typedef struct value * (frame_prev_register_ftype) 126 (struct frame_info *this_frame, void **this_prologue_cache, 127 int regnum); 128 129 /* Deallocate extra memory associated with the frame cache if any. */ 130 131 typedef void (frame_dealloc_cache_ftype) (struct frame_info *self, 132 void *this_cache); 133 134 /* Assuming the frame chain: (outer) prev <-> this <-> next (inner); 135 use THIS frame, and implicitly the NEXT frame's register unwind 136 method, return PREV frame's architecture. */ 137 138 typedef struct gdbarch *(frame_prev_arch_ftype) (struct frame_info *this_frame, 139 void **this_prologue_cache); 140 141 struct frame_unwind 142 { 143 /* The frame's type. Should this instead be a collection of 144 predicates that test the frame for various attributes? */ 145 enum frame_type type; 146 /* Should an attribute indicating the frame's address-in-block go 147 here? */ 148 frame_unwind_stop_reason_ftype *stop_reason; 149 frame_this_id_ftype *this_id; 150 frame_prev_register_ftype *prev_register; 151 const struct frame_data *unwind_data; 152 frame_sniffer_ftype *sniffer; 153 frame_dealloc_cache_ftype *dealloc_cache; 154 frame_prev_arch_ftype *prev_arch; 155 }; 156 157 /* Register a frame unwinder, _prepending_ it to the front of the 158 search list (so it is sniffed before previously registered 159 unwinders). By using a prepend, later calls can install unwinders 160 that override earlier calls. This allows, for instance, an OSABI 161 to install a more specific sigtramp unwinder that overrides the 162 traditional brute-force unwinder. */ 163 extern void frame_unwind_prepend_unwinder (struct gdbarch *, 164 const struct frame_unwind *); 165 166 /* Add a frame sniffer to the list. The predicates are polled in the 167 order that they are appended. The initial list contains the dummy 168 frame sniffer. */ 169 170 extern void frame_unwind_append_unwinder (struct gdbarch *gdbarch, 171 const struct frame_unwind *unwinder); 172 173 /* Iterate through sniffers for THIS_FRAME frame until one returns with an 174 unwinder implementation. THIS_FRAME->UNWIND must be NULL, it will get set 175 by this function. Possibly initialize THIS_CACHE. */ 176 177 extern void frame_unwind_find_by_frame (struct frame_info *this_frame, 178 void **this_cache); 179 180 /* Helper functions for value-based register unwinding. These return 181 a (possibly lazy) value of the appropriate type. */ 182 183 /* Return a value which indicates that FRAME did not save REGNUM. */ 184 185 struct value *frame_unwind_got_optimized (struct frame_info *frame, 186 int regnum); 187 188 /* Return a value which indicates that FRAME copied REGNUM into 189 register NEW_REGNUM. */ 190 191 struct value *frame_unwind_got_register (struct frame_info *frame, int regnum, 192 int new_regnum); 193 194 /* Return a value which indicates that FRAME saved REGNUM in memory at 195 ADDR. */ 196 197 struct value *frame_unwind_got_memory (struct frame_info *frame, int regnum, 198 CORE_ADDR addr); 199 200 /* Return a value which indicates that FRAME's saved version of 201 REGNUM has a known constant (computed) value of VAL. */ 202 203 struct value *frame_unwind_got_constant (struct frame_info *frame, int regnum, 204 ULONGEST val); 205 206 /* Return a value which indicates that FRAME's saved version of 207 REGNUM has a known constant (computed) value which is stored 208 inside BUF. */ 209 210 struct value *frame_unwind_got_bytes (struct frame_info *frame, int regnum, 211 gdb_byte *buf); 212 213 /* Return a value which indicates that FRAME's saved version of REGNUM 214 has a known constant (computed) value of ADDR. Convert the 215 CORE_ADDR to a target address if necessary. */ 216 217 struct value *frame_unwind_got_address (struct frame_info *frame, int regnum, 218 CORE_ADDR addr); 219 220 #endif 221