1 /* Signal trampoline unwinder, for GDB the GNU Debugger. 2 3 Copyright 2004 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 2 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, write to the Free Software 19 Foundation, Inc., 59 Temple Place - Suite 330, 20 Boston, MA 02111-1307, USA. */ 21 22 #include "defs.h" 23 #include "tramp-frame.h" 24 #include "frame-unwind.h" 25 #include "gdbcore.h" 26 #include "symtab.h" 27 #include "objfiles.h" 28 #include "target.h" 29 #include "trad-frame.h" 30 #include "frame-base.h" 31 #include "gdb_assert.h" 32 33 struct frame_data 34 { 35 const struct tramp_frame *tramp_frame; 36 }; 37 38 struct tramp_frame_cache 39 { 40 CORE_ADDR func; 41 const struct tramp_frame *tramp_frame; 42 struct trad_frame_cache *trad_cache; 43 }; 44 45 static struct trad_frame_cache * 46 tramp_frame_cache (struct frame_info *next_frame, 47 void **this_cache) 48 { 49 CORE_ADDR pc = frame_pc_unwind (next_frame); 50 struct tramp_frame_cache *tramp_cache = (*this_cache); 51 if (tramp_cache->trad_cache == NULL) 52 { 53 tramp_cache->trad_cache = trad_frame_cache_zalloc (next_frame); 54 tramp_cache->tramp_frame->init (tramp_cache->tramp_frame, 55 next_frame, 56 tramp_cache->trad_cache, 57 tramp_cache->func); 58 } 59 return tramp_cache->trad_cache; 60 } 61 62 static void 63 tramp_frame_this_id (struct frame_info *next_frame, 64 void **this_cache, 65 struct frame_id *this_id) 66 { 67 struct trad_frame_cache *trad_cache 68 = tramp_frame_cache (next_frame, this_cache); 69 trad_frame_get_id (trad_cache, this_id); 70 } 71 72 static void 73 tramp_frame_prev_register (struct frame_info *next_frame, 74 void **this_cache, 75 int prev_regnum, 76 int *optimizedp, 77 enum lval_type * lvalp, 78 CORE_ADDR *addrp, 79 int *realnump, void *valuep) 80 { 81 struct trad_frame_cache *trad_cache 82 = tramp_frame_cache (next_frame, this_cache); 83 trad_frame_get_register (trad_cache, next_frame, prev_regnum, optimizedp, 84 lvalp, addrp, realnump, valuep); 85 } 86 87 static CORE_ADDR 88 tramp_frame_start (const struct tramp_frame *tramp, 89 struct frame_info *next_frame, CORE_ADDR pc) 90 { 91 int ti; 92 /* Search through the trampoline for one that matches the 93 instruction sequence around PC. */ 94 for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++) 95 { 96 CORE_ADDR func = pc - tramp->insn_size * ti; 97 int i; 98 for (i = 0; 1; i++) 99 { 100 bfd_byte buf[sizeof (tramp->insn[0])]; 101 ULONGEST insn; 102 if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN) 103 return func; 104 if (!safe_frame_unwind_memory (next_frame, 105 func + i * tramp->insn_size, 106 buf, tramp->insn_size)) 107 break; 108 insn = extract_unsigned_integer (buf, tramp->insn_size); 109 if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask)) 110 break; 111 } 112 } 113 /* Trampoline doesn't match. */ 114 return 0; 115 } 116 117 static int 118 tramp_frame_sniffer (const struct frame_unwind *self, 119 struct frame_info *next_frame, 120 void **this_cache) 121 { 122 const struct tramp_frame *tramp = self->unwind_data->tramp_frame; 123 CORE_ADDR pc = frame_pc_unwind (next_frame); 124 CORE_ADDR func; 125 char *name; 126 struct tramp_frame_cache *tramp_cache; 127 128 /* If the function has a valid symbol name, it isn't a 129 trampoline. */ 130 find_pc_partial_function (pc, &name, NULL, NULL); 131 if (name != NULL) 132 return 0; 133 /* If the function lives in a valid section (even without a starting 134 point) it isn't a trampoline. */ 135 if (find_pc_section (pc) != NULL) 136 return 0; 137 /* Finally, check that the trampoline matches at PC. */ 138 func = tramp_frame_start (tramp, next_frame, pc); 139 if (func == 0) 140 return 0; 141 tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache); 142 tramp_cache->func = func; 143 tramp_cache->tramp_frame = tramp; 144 (*this_cache) = tramp_cache; 145 return 1; 146 } 147 148 void 149 tramp_frame_prepend_unwinder (struct gdbarch *gdbarch, 150 const struct tramp_frame *tramp_frame) 151 { 152 struct frame_data *data; 153 struct frame_unwind *unwinder; 154 int i; 155 156 /* Check that the instruction sequence contains a sentinel. */ 157 for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++) 158 { 159 if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN) 160 break; 161 } 162 gdb_assert (i < ARRAY_SIZE (tramp_frame->insn)); 163 gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes)); 164 165 data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data); 166 unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind); 167 168 data->tramp_frame = tramp_frame; 169 unwinder->type = SIGTRAMP_FRAME; 170 unwinder->unwind_data = data; 171 unwinder->sniffer = tramp_frame_sniffer; 172 unwinder->this_id = tramp_frame_this_id; 173 unwinder->prev_register = tramp_frame_prev_register; 174 frame_unwind_prepend_unwinder (gdbarch, unwinder); 175 } 176