1 /* Definitions for a frame unwinder, for GDB, the GNU debugger. 2 3 Copyright (C) 2003, 2004, 2007, 2008, 2009 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 the next frame's `struct frame_info' 36 and this frame's 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 /* A default frame sniffer which always accepts the frame. Used by 54 fallback prologue unwinders. */ 55 56 int default_frame_sniffer (const struct frame_unwind *self, 57 struct frame_info *this_frame, 58 void **this_prologue_cache); 59 60 /* Assuming the frame chain: (outer) prev <-> this <-> next (inner); 61 use THIS frame, and through it the NEXT frame's register unwind 62 method, to determine the frame ID of THIS frame. 63 64 A frame ID provides an invariant that can be used to re-identify an 65 instance of a frame. It is a combination of the frame's `base' and 66 the frame's function's code address. 67 68 Traditionally, THIS frame's ID was determined by examining THIS 69 frame's function's prologue, and identifying the register/offset 70 used as THIS frame's base. 71 72 Example: An examination of THIS frame's prologue reveals that, on 73 entry, it saves the PC(+12), SP(+8), and R1(+4) registers 74 (decrementing the SP by 12). Consequently, the frame ID's base can 75 be determined by adding 12 to the THIS frame's stack-pointer, and 76 the value of THIS frame's SP can be obtained by unwinding the NEXT 77 frame's SP. 78 79 THIS_PROLOGUE_CACHE can be used to share any prolog analysis data 80 with the other unwind methods. Memory for that cache should be 81 allocated using FRAME_OBSTACK_ZALLOC(). */ 82 83 typedef void (frame_this_id_ftype) (struct frame_info *this_frame, 84 void **this_prologue_cache, 85 struct frame_id *this_id); 86 87 /* Assuming the frame chain: (outer) prev <-> this <-> next (inner); 88 use THIS frame, and implicitly the NEXT frame's register unwind 89 method, to unwind THIS frame's registers (returning the value of 90 the specified register REGNUM in the previous frame). 91 92 Traditionally, THIS frame's registers were unwound by examining 93 THIS frame's function's prologue and identifying which registers 94 that prolog code saved on the stack. 95 96 Example: An examination of THIS frame's prologue reveals that, on 97 entry, it saves the PC(+12), SP(+8), and R1(+4) registers 98 (decrementing the SP by 12). Consequently, the value of the PC 99 register in the previous frame is found in memory at SP+12, and 100 THIS frame's SP can be obtained by unwinding the NEXT frame's SP. 101 102 This function takes THIS_FRAME as an argument. It can find the 103 values of registers in THIS frame by calling get_frame_register 104 (THIS_FRAME), and reinvoke itself to find other registers in the 105 PREVIOUS frame by calling frame_unwind_register (THIS_FRAME). 106 107 The result is a GDB value object describing the register value. It 108 may be a lazy reference to memory, a lazy reference to the value of 109 a register in THIS frame, or a non-lvalue. 110 111 THIS_PROLOGUE_CACHE can be used to share any prolog analysis data 112 with the other unwind methods. Memory for that cache should be 113 allocated using FRAME_OBSTACK_ZALLOC(). */ 114 115 typedef struct value * (frame_prev_register_ftype) 116 (struct frame_info *this_frame, void **this_prologue_cache, 117 int regnum); 118 119 /* Deallocate extra memory associated with the frame cache if any. */ 120 121 typedef void (frame_dealloc_cache_ftype) (struct frame_info *self, 122 void *this_cache); 123 124 /* Assuming the frame chain: (outer) prev <-> this <-> next (inner); 125 use THIS frame, and implicitly the NEXT frame's register unwind 126 method, return PREV frame's architecture. */ 127 128 typedef struct gdbarch *(frame_prev_arch_ftype) (struct frame_info *this_frame, 129 void **this_prologue_cache); 130 131 struct frame_unwind 132 { 133 /* The frame's type. Should this instead be a collection of 134 predicates that test the frame for various attributes? */ 135 enum frame_type type; 136 /* Should an attribute indicating the frame's address-in-block go 137 here? */ 138 frame_this_id_ftype *this_id; 139 frame_prev_register_ftype *prev_register; 140 const struct frame_data *unwind_data; 141 frame_sniffer_ftype *sniffer; 142 frame_dealloc_cache_ftype *dealloc_cache; 143 frame_prev_arch_ftype *prev_arch; 144 }; 145 146 /* Register a frame unwinder, _prepending_ it to the front of the 147 search list (so it is sniffed before previously registered 148 unwinders). By using a prepend, later calls can install unwinders 149 that override earlier calls. This allows, for instance, an OSABI 150 to install a a more specific sigtramp unwinder that overrides the 151 traditional brute-force unwinder. */ 152 extern void frame_unwind_prepend_unwinder (struct gdbarch *gdbarch, 153 const struct frame_unwind *unwinder); 154 155 /* Add a frame sniffer to the list. The predicates are polled in the 156 order that they are appended. The initial list contains the dummy 157 frame sniffer. */ 158 159 extern void frame_unwind_append_unwinder (struct gdbarch *gdbarch, 160 const struct frame_unwind *unwinder); 161 162 /* Iterate through sniffers for THIS frame until one returns with an 163 unwinder implementation. Possibly initialize THIS_CACHE. */ 164 165 extern const struct frame_unwind *frame_unwind_find_by_frame (struct frame_info *this_frame, 166 void **this_cache); 167 168 /* Helper functions for value-based register unwinding. These return 169 a (possibly lazy) value of the appropriate type. */ 170 171 /* Return a value which indicates that FRAME did not save REGNUM. */ 172 173 struct value *frame_unwind_got_optimized (struct frame_info *frame, 174 int regnum); 175 176 /* Return a value which indicates that FRAME copied REGNUM into 177 register NEW_REGNUM. */ 178 179 struct value *frame_unwind_got_register (struct frame_info *frame, int regnum, 180 int new_regnum); 181 182 /* Return a value which indicates that FRAME saved REGNUM in memory at 183 ADDR. */ 184 185 struct value *frame_unwind_got_memory (struct frame_info *frame, int regnum, 186 CORE_ADDR addr); 187 188 /* Return a value which indicates that FRAME's saved version of 189 REGNUM has a known constant (computed) value of VAL. */ 190 191 struct value *frame_unwind_got_constant (struct frame_info *frame, int regnum, 192 ULONGEST val); 193 194 /* Return a value which indicates that FRAME's saved version of 195 REGNUM has a known constant (computed) value which is stored 196 inside BUF. */ 197 198 struct value *frame_unwind_got_bytes (struct frame_info *frame, int regnum, 199 gdb_byte *buf); 200 201 /* Return a value which indicates that FRAME's saved version of REGNUM 202 has a known constant (computed) value of ADDR. Convert the 203 CORE_ADDR to a target address if necessary. */ 204 205 struct value *frame_unwind_got_address (struct frame_info *frame, int regnum, 206 CORE_ADDR addr); 207 208 #endif 209