1 /* Definitions for a frame unwinder, for GDB, the GNU debugger. 2 3 Copyright (C) 2003, 2004, 2007, 2008, 2009, 2010 4 Free Software Foundation, Inc. 5 6 This file is part of GDB. 7 8 This program is free software; you can redistribute it and/or modify 9 it under the terms of the GNU General Public License as published by 10 the Free Software Foundation; either version 3 of the License, or 11 (at your option) any later version. 12 13 This program is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 GNU General Public License for more details. 17 18 You should have received a copy of the GNU General Public License 19 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 20 21 #if !defined (FRAME_UNWIND_H) 22 #define FRAME_UNWIND_H 1 23 24 struct frame_data; 25 struct frame_info; 26 struct frame_id; 27 struct frame_unwind; 28 struct gdbarch; 29 struct regcache; 30 struct value; 31 32 #include "frame.h" /* For enum frame_type. */ 33 34 /* The following unwind functions assume a chain of frames forming the 35 sequence: (outer) prev <-> this <-> next (inner). All the 36 functions are called with the next frame's `struct frame_info' 37 and this frame's prologue cache. 38 39 THIS frame's register values can be obtained by unwinding NEXT 40 frame's registers (a recursive operation). 41 42 THIS frame's prologue cache can be used to cache information such 43 as where this frame's prologue stores the previous frame's 44 registers. */ 45 46 /* Given THIS frame, take a whiff of its registers (namely 47 the PC and attributes) and if SELF is the applicable unwinder, 48 return non-zero. Possibly also initialize THIS_PROLOGUE_CACHE. */ 49 50 typedef int (frame_sniffer_ftype) (const struct frame_unwind *self, 51 struct frame_info *this_frame, 52 void **this_prologue_cache); 53 54 /* A default frame sniffer which always accepts the frame. Used by 55 fallback prologue unwinders. */ 56 57 int default_frame_sniffer (const struct frame_unwind *self, 58 struct frame_info *this_frame, 59 void **this_prologue_cache); 60 61 /* Assuming the frame chain: (outer) prev <-> this <-> next (inner); 62 use THIS frame, and through it the NEXT frame's register unwind 63 method, to determine the frame ID of THIS frame. 64 65 A frame ID provides an invariant that can be used to re-identify an 66 instance of a frame. It is a combination of the frame's `base' and 67 the frame's function's code address. 68 69 Traditionally, THIS frame's ID was determined by examining THIS 70 frame's function's prologue, and identifying the register/offset 71 used as THIS frame's base. 72 73 Example: An examination of THIS frame's prologue reveals that, on 74 entry, it saves the PC(+12), SP(+8), and R1(+4) registers 75 (decrementing the SP by 12). Consequently, the frame ID's base can 76 be determined by adding 12 to the THIS frame's stack-pointer, and 77 the value of THIS frame's SP can be obtained by unwinding the NEXT 78 frame's SP. 79 80 THIS_PROLOGUE_CACHE can be used to share any prolog analysis data 81 with the other unwind methods. Memory for that cache should be 82 allocated using FRAME_OBSTACK_ZALLOC(). */ 83 84 typedef void (frame_this_id_ftype) (struct frame_info *this_frame, 85 void **this_prologue_cache, 86 struct frame_id *this_id); 87 88 /* Assuming the frame chain: (outer) prev <-> this <-> next (inner); 89 use THIS frame, and implicitly the NEXT frame's register unwind 90 method, to unwind THIS frame's registers (returning the value of 91 the specified register REGNUM in the previous frame). 92 93 Traditionally, THIS frame's registers were unwound by examining 94 THIS frame's function's prologue and identifying which registers 95 that prolog code saved on the stack. 96 97 Example: An examination of THIS frame's prologue reveals that, on 98 entry, it saves the PC(+12), SP(+8), and R1(+4) registers 99 (decrementing the SP by 12). Consequently, the value of the PC 100 register in the previous frame is found in memory at SP+12, and 101 THIS frame's SP can be obtained by unwinding the NEXT frame's SP. 102 103 This function takes THIS_FRAME as an argument. It can find the 104 values of registers in THIS frame by calling get_frame_register 105 (THIS_FRAME), and reinvoke itself to find other registers in the 106 PREVIOUS frame by calling frame_unwind_register (THIS_FRAME). 107 108 The result is a GDB value object describing the register value. It 109 may be a lazy reference to memory, a lazy reference to the value of 110 a register in THIS frame, or a non-lvalue. 111 112 THIS_PROLOGUE_CACHE can be used to share any prolog analysis data 113 with the other unwind methods. Memory for that cache should be 114 allocated using FRAME_OBSTACK_ZALLOC(). */ 115 116 typedef struct value * (frame_prev_register_ftype) 117 (struct frame_info *this_frame, void **this_prologue_cache, 118 int regnum); 119 120 /* Deallocate extra memory associated with the frame cache if any. */ 121 122 typedef void (frame_dealloc_cache_ftype) (struct frame_info *self, 123 void *this_cache); 124 125 /* Assuming the frame chain: (outer) prev <-> this <-> next (inner); 126 use THIS frame, and implicitly the NEXT frame's register unwind 127 method, return PREV frame's architecture. */ 128 129 typedef struct gdbarch *(frame_prev_arch_ftype) (struct frame_info *this_frame, 130 void **this_prologue_cache); 131 132 struct frame_unwind 133 { 134 /* The frame's type. Should this instead be a collection of 135 predicates that test the frame for various attributes? */ 136 enum frame_type type; 137 /* Should an attribute indicating the frame's address-in-block go 138 here? */ 139 frame_this_id_ftype *this_id; 140 frame_prev_register_ftype *prev_register; 141 const struct frame_data *unwind_data; 142 frame_sniffer_ftype *sniffer; 143 frame_dealloc_cache_ftype *dealloc_cache; 144 frame_prev_arch_ftype *prev_arch; 145 }; 146 147 /* Register a frame unwinder, _prepending_ it to the front of the 148 search list (so it is sniffed before previously registered 149 unwinders). By using a prepend, later calls can install unwinders 150 that override earlier calls. This allows, for instance, an OSABI 151 to install a a more specific sigtramp unwinder that overrides the 152 traditional brute-force unwinder. */ 153 extern void frame_unwind_prepend_unwinder (struct gdbarch *gdbarch, 154 const struct frame_unwind *unwinder); 155 156 /* Add a frame sniffer to the list. The predicates are polled in the 157 order that they are appended. The initial list contains the dummy 158 frame sniffer. */ 159 160 extern void frame_unwind_append_unwinder (struct gdbarch *gdbarch, 161 const struct frame_unwind *unwinder); 162 163 /* Iterate through sniffers for THIS frame until one returns with an 164 unwinder implementation. Possibly initialize THIS_CACHE. */ 165 166 extern const struct frame_unwind *frame_unwind_find_by_frame (struct frame_info *this_frame, 167 void **this_cache); 168 169 /* Helper functions for value-based register unwinding. These return 170 a (possibly lazy) value of the appropriate type. */ 171 172 /* Return a value which indicates that FRAME did not save REGNUM. */ 173 174 struct value *frame_unwind_got_optimized (struct frame_info *frame, 175 int regnum); 176 177 /* Return a value which indicates that FRAME copied REGNUM into 178 register NEW_REGNUM. */ 179 180 struct value *frame_unwind_got_register (struct frame_info *frame, int regnum, 181 int new_regnum); 182 183 /* Return a value which indicates that FRAME saved REGNUM in memory at 184 ADDR. */ 185 186 struct value *frame_unwind_got_memory (struct frame_info *frame, int regnum, 187 CORE_ADDR addr); 188 189 /* Return a value which indicates that FRAME's saved version of 190 REGNUM has a known constant (computed) value of VAL. */ 191 192 struct value *frame_unwind_got_constant (struct frame_info *frame, int regnum, 193 ULONGEST val); 194 195 /* Return a value which indicates that FRAME's saved version of 196 REGNUM has a known constant (computed) value which is stored 197 inside BUF. */ 198 199 struct value *frame_unwind_got_bytes (struct frame_info *frame, int regnum, 200 gdb_byte *buf); 201 202 /* Return a value which indicates that FRAME's saved version of REGNUM 203 has a known constant (computed) value of ADDR. Convert the 204 CORE_ADDR to a target address if necessary. */ 205 206 struct value *frame_unwind_got_address (struct frame_info *frame, int regnum, 207 CORE_ADDR addr); 208 209 #endif 210