1 /* Signal trampoline unwinder, for GDB the GNU Debugger. 2 3 Copyright (C) 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 #include "defs.h" 21 #include "tramp-frame.h" 22 #include "frame-unwind.h" 23 #include "gdbcore.h" 24 #include "symtab.h" 25 #include "objfiles.h" 26 #include "target.h" 27 #include "trad-frame.h" 28 #include "frame-base.h" 29 #include "gdb_assert.h" 30 31 struct frame_data 32 { 33 const struct tramp_frame *tramp_frame; 34 }; 35 36 struct tramp_frame_cache 37 { 38 CORE_ADDR func; 39 const struct tramp_frame *tramp_frame; 40 struct trad_frame_cache *trad_cache; 41 }; 42 43 static struct trad_frame_cache * 44 tramp_frame_cache (struct frame_info *this_frame, 45 void **this_cache) 46 { 47 CORE_ADDR pc = get_frame_pc (this_frame); 48 struct tramp_frame_cache *tramp_cache = (*this_cache); 49 if (tramp_cache->trad_cache == NULL) 50 { 51 tramp_cache->trad_cache = trad_frame_cache_zalloc (this_frame); 52 tramp_cache->tramp_frame->init (tramp_cache->tramp_frame, 53 this_frame, 54 tramp_cache->trad_cache, 55 tramp_cache->func); 56 } 57 return tramp_cache->trad_cache; 58 } 59 60 static void 61 tramp_frame_this_id (struct frame_info *this_frame, 62 void **this_cache, 63 struct frame_id *this_id) 64 { 65 struct trad_frame_cache *trad_cache 66 = tramp_frame_cache (this_frame, this_cache); 67 trad_frame_get_id (trad_cache, this_id); 68 } 69 70 static struct value * 71 tramp_frame_prev_register (struct frame_info *this_frame, 72 void **this_cache, 73 int prev_regnum) 74 { 75 struct trad_frame_cache *trad_cache 76 = tramp_frame_cache (this_frame, this_cache); 77 return trad_frame_get_register (trad_cache, this_frame, prev_regnum); 78 } 79 80 static CORE_ADDR 81 tramp_frame_start (const struct tramp_frame *tramp, 82 struct frame_info *this_frame, CORE_ADDR pc) 83 { 84 struct gdbarch *gdbarch = get_frame_arch (this_frame); 85 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); 86 int ti; 87 /* Search through the trampoline for one that matches the 88 instruction sequence around PC. */ 89 for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++) 90 { 91 CORE_ADDR func = pc - tramp->insn_size * ti; 92 int i; 93 for (i = 0; 1; i++) 94 { 95 gdb_byte buf[sizeof (tramp->insn[0])]; 96 ULONGEST insn; 97 if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN) 98 return func; 99 if (!safe_frame_unwind_memory (this_frame, 100 func + i * tramp->insn_size, 101 buf, tramp->insn_size)) 102 break; 103 insn = extract_unsigned_integer (buf, tramp->insn_size, byte_order); 104 if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask)) 105 break; 106 } 107 } 108 /* Trampoline doesn't match. */ 109 return 0; 110 } 111 112 static int 113 tramp_frame_sniffer (const struct frame_unwind *self, 114 struct frame_info *this_frame, 115 void **this_cache) 116 { 117 const struct tramp_frame *tramp = self->unwind_data->tramp_frame; 118 CORE_ADDR pc = get_frame_pc (this_frame); 119 CORE_ADDR func; 120 struct tramp_frame_cache *tramp_cache; 121 122 /* tausq/2004-12-12: We used to assume if pc has a name or is in a valid 123 section, then this is not a trampoline. However, this assumption is 124 false on HPUX which has a signal trampoline that has a name; it can 125 also be false when using an alternative signal stack. */ 126 func = tramp_frame_start (tramp, this_frame, pc); 127 if (func == 0) 128 return 0; 129 tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache); 130 tramp_cache->func = func; 131 tramp_cache->tramp_frame = tramp; 132 (*this_cache) = tramp_cache; 133 return 1; 134 } 135 136 void 137 tramp_frame_prepend_unwinder (struct gdbarch *gdbarch, 138 const struct tramp_frame *tramp_frame) 139 { 140 struct frame_data *data; 141 struct frame_unwind *unwinder; 142 int i; 143 144 /* Check that the instruction sequence contains a sentinel. */ 145 for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++) 146 { 147 if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN) 148 break; 149 } 150 gdb_assert (i < ARRAY_SIZE (tramp_frame->insn)); 151 gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes)); 152 153 data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data); 154 unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind); 155 156 data->tramp_frame = tramp_frame; 157 unwinder->type = tramp_frame->frame_type; 158 unwinder->unwind_data = data; 159 unwinder->sniffer = tramp_frame_sniffer; 160 unwinder->this_id = tramp_frame_this_id; 161 unwinder->prev_register = tramp_frame_prev_register; 162 frame_unwind_prepend_unwinder (gdbarch, unwinder); 163 } 164