| 1 | /* Code dealing with dummy stack frames, for GDB, the GNU debugger. |
| 2 | |
| 3 | Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, |
| 4 | 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2007, 2008 |
| 5 | Free Software Foundation, Inc. |
| 6 | |
| 7 | This file is part of GDB. |
| 8 | |
| 9 | This program is free software; you can redistribute it and/or modify |
| 10 | it under the terms of the GNU General Public License as published by |
| 11 | the Free Software Foundation; either version 3 of the License, or |
| 12 | (at your option) any later version. |
| 13 | |
| 14 | This program is distributed in the hope that it will be useful, |
| 15 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 17 | GNU General Public License for more details. |
| 18 | |
| 19 | You should have received a copy of the GNU General Public License |
| 20 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 21 | |
| 22 | |
| 23 | #include "defs.h" |
| 24 | #include "dummy-frame.h" |
| 25 | #include "regcache.h" |
| 26 | #include "frame.h" |
| 27 | #include "inferior.h" |
| 28 | #include "gdb_assert.h" |
| 29 | #include "frame-unwind.h" |
| 30 | #include "command.h" |
| 31 | #include "gdbcmd.h" |
| 32 | #include "gdb_string.h" |
| 33 | #include "observer.h" |
| 34 | |
| 35 | /* Dummy frame. This saves the processor state just prior to setting |
| 36 | up the inferior function call. Older targets save the registers |
| 37 | on the target stack (but that really slows down function calls). */ |
| 38 | |
| 39 | struct dummy_frame |
| 40 | { |
| 41 | struct dummy_frame *next; |
| 42 | /* This frame's ID. Must match the value returned by |
| 43 | gdbarch_dummy_id. */ |
| 44 | struct frame_id id; |
| 45 | /* The caller's regcache. */ |
| 46 | struct regcache *regcache; |
| 47 | }; |
| 48 | |
| 49 | static struct dummy_frame *dummy_frame_stack = NULL; |
| 50 | |
| 51 | /* Function: deprecated_pc_in_call_dummy (pc) |
| 52 | |
| 53 | Return non-zero if the PC falls in a dummy frame created by gdb for |
| 54 | an inferior call. The code below which allows gdbarch_decr_pc_after_break |
| 55 | is for infrun.c, which may give the function a PC without that |
| 56 | subtracted out. |
| 57 | |
| 58 | FIXME: cagney/2002-11-23: This is silly. Surely "infrun.c" can |
| 59 | figure out what the real PC (as in the resume address) is BEFORE |
| 60 | calling this function. |
| 61 | |
| 62 | NOTE: cagney/2004-08-02: I'm pretty sure that, with the introduction of |
| 63 | infrun.c:adjust_pc_after_break (thanks), this function is now |
| 64 | always called with a correctly adjusted PC! |
| 65 | |
| 66 | NOTE: cagney/2004-08-02: Code should not need to call this. */ |
| 67 | |
| 68 | int |
| 69 | deprecated_pc_in_call_dummy (CORE_ADDR pc) |
| 70 | { |
| 71 | struct dummy_frame *dummyframe; |
| 72 | for (dummyframe = dummy_frame_stack; |
| 73 | dummyframe != NULL; |
| 74 | dummyframe = dummyframe->next) |
| 75 | { |
| 76 | if ((pc >= dummyframe->id.code_addr) |
| 77 | && (pc <= dummyframe->id.code_addr |
| 78 | + gdbarch_decr_pc_after_break (current_gdbarch))) |
| 79 | return 1; |
| 80 | } |
| 81 | return 0; |
| 82 | } |
| 83 | |
| 84 | /* Push the caller's state, along with the dummy frame info, onto a |
| 85 | dummy-frame stack. */ |
| 86 | |
| 87 | void |
| 88 | dummy_frame_push (struct regcache *caller_regcache, |
| 89 | const struct frame_id *dummy_id) |
| 90 | { |
| 91 | struct dummy_frame *dummy_frame; |
| 92 | |
| 93 | dummy_frame = XZALLOC (struct dummy_frame); |
| 94 | dummy_frame->regcache = caller_regcache; |
| 95 | dummy_frame->id = (*dummy_id); |
| 96 | dummy_frame->next = dummy_frame_stack; |
| 97 | dummy_frame_stack = dummy_frame; |
| 98 | } |
| 99 | |
| 100 | /* Pop the dummy frame with ID dummy_id from the dummy-frame stack. */ |
| 101 | |
| 102 | void |
| 103 | dummy_frame_pop (struct frame_id dummy_id) |
| 104 | { |
| 105 | struct dummy_frame **dummy_ptr; |
| 106 | |
| 107 | for (dummy_ptr = &dummy_frame_stack; |
| 108 | (*dummy_ptr) != NULL; |
| 109 | dummy_ptr = &(*dummy_ptr)->next) |
| 110 | { |
| 111 | struct dummy_frame *dummy = *dummy_ptr; |
| 112 | if (frame_id_eq (dummy->id, dummy_id)) |
| 113 | { |
| 114 | *dummy_ptr = dummy->next; |
| 115 | regcache_xfree (dummy->regcache); |
| 116 | xfree (dummy); |
| 117 | break; |
| 118 | } |
| 119 | } |
| 120 | } |
| 121 | |
| 122 | /* There may be stale dummy frames, perhaps left over from when a longjump took us |
| 123 | out of a function that was called by the debugger. Clean them up at least once |
| 124 | whenever we start a new inferior. */ |
| 125 | |
| 126 | static void |
| 127 | cleanup_dummy_frames (struct target_ops *target, int from_tty) |
| 128 | { |
| 129 | struct dummy_frame *dummy, *next; |
| 130 | |
| 131 | for (dummy = dummy_frame_stack; dummy; dummy = next) |
| 132 | { |
| 133 | next = dummy->next; |
| 134 | regcache_xfree (dummy->regcache); |
| 135 | xfree (dummy); |
| 136 | } |
| 137 | |
| 138 | dummy_frame_stack = NULL; |
| 139 | } |
| 140 | |
| 141 | /* Return the dummy frame cache, it contains both the ID, and a |
| 142 | pointer to the regcache. */ |
| 143 | struct dummy_frame_cache |
| 144 | { |
| 145 | struct frame_id this_id; |
| 146 | struct regcache *prev_regcache; |
| 147 | }; |
| 148 | |
| 149 | int |
| 150 | dummy_frame_sniffer (const struct frame_unwind *self, |
| 151 | struct frame_info *this_frame, |
| 152 | void **this_prologue_cache) |
| 153 | { |
| 154 | struct dummy_frame *dummyframe; |
| 155 | struct frame_id this_id; |
| 156 | |
| 157 | /* When unwinding a normal frame, the stack structure is determined |
| 158 | by analyzing the frame's function's code (be it using brute force |
| 159 | prologue analysis, or the dwarf2 CFI). In the case of a dummy |
| 160 | frame, that simply isn't possible. The PC is either the program |
| 161 | entry point, or some random address on the stack. Trying to use |
| 162 | that PC to apply standard frame ID unwind techniques is just |
| 163 | asking for trouble. */ |
| 164 | |
| 165 | /* Don't bother unles there is at least one dummy frame. */ |
| 166 | if (dummy_frame_stack != NULL) |
| 167 | { |
| 168 | /* Use an architecture specific method to extract this frame's |
| 169 | dummy ID, assuming it is a dummy frame. */ |
| 170 | this_id = gdbarch_dummy_id (get_frame_arch (this_frame), this_frame); |
| 171 | |
| 172 | /* Use that ID to find the corresponding cache entry. */ |
| 173 | for (dummyframe = dummy_frame_stack; |
| 174 | dummyframe != NULL; |
| 175 | dummyframe = dummyframe->next) |
| 176 | { |
| 177 | if (frame_id_eq (dummyframe->id, this_id)) |
| 178 | { |
| 179 | struct dummy_frame_cache *cache; |
| 180 | cache = FRAME_OBSTACK_ZALLOC (struct dummy_frame_cache); |
| 181 | cache->prev_regcache = dummyframe->regcache; |
| 182 | cache->this_id = this_id; |
| 183 | (*this_prologue_cache) = cache; |
| 184 | return 1; |
| 185 | } |
| 186 | } |
| 187 | } |
| 188 | return 0; |
| 189 | } |
| 190 | |
| 191 | /* Given a call-dummy dummy-frame, return the registers. Here the |
| 192 | register value is taken from the local copy of the register buffer. */ |
| 193 | |
| 194 | static struct value * |
| 195 | dummy_frame_prev_register (struct frame_info *this_frame, |
| 196 | void **this_prologue_cache, |
| 197 | int regnum) |
| 198 | { |
| 199 | struct dummy_frame_cache *cache = (*this_prologue_cache); |
| 200 | struct gdbarch *gdbarch = get_frame_arch (this_frame); |
| 201 | struct value *reg_val; |
| 202 | |
| 203 | /* The dummy-frame sniffer always fills in the cache. */ |
| 204 | gdb_assert (cache != NULL); |
| 205 | |
| 206 | /* Describe the register's location. Generic dummy frames always |
| 207 | have the register value in an ``expression''. */ |
| 208 | reg_val = value_zero (register_type (gdbarch, regnum), not_lval); |
| 209 | |
| 210 | /* Use the regcache_cooked_read() method so that it, on the fly, |
| 211 | constructs either a raw or pseudo register from the raw |
| 212 | register cache. */ |
| 213 | regcache_cooked_read (cache->prev_regcache, regnum, |
| 214 | value_contents_writeable (reg_val)); |
| 215 | return reg_val; |
| 216 | } |
| 217 | |
| 218 | /* Assuming that THIS frame is a dummy, return the ID of THIS frame. That ID is |
| 219 | determined by examining the NEXT frame's unwound registers using |
| 220 | the method dummy_id(). As a side effect, THIS dummy frame's |
| 221 | dummy cache is located and and saved in THIS_PROLOGUE_CACHE. */ |
| 222 | |
| 223 | static void |
| 224 | dummy_frame_this_id (struct frame_info *this_frame, |
| 225 | void **this_prologue_cache, |
| 226 | struct frame_id *this_id) |
| 227 | { |
| 228 | /* The dummy-frame sniffer always fills in the cache. */ |
| 229 | struct dummy_frame_cache *cache = (*this_prologue_cache); |
| 230 | gdb_assert (cache != NULL); |
| 231 | (*this_id) = cache->this_id; |
| 232 | } |
| 233 | |
| 234 | static const struct frame_unwind dummy_frame_unwinder = |
| 235 | { |
| 236 | DUMMY_FRAME, |
| 237 | dummy_frame_this_id, |
| 238 | dummy_frame_prev_register, |
| 239 | NULL, |
| 240 | dummy_frame_sniffer, |
| 241 | }; |
| 242 | |
| 243 | const struct frame_unwind *const dummy_frame_unwind = { |
| 244 | &dummy_frame_unwinder |
| 245 | }; |
| 246 | |
| 247 | static void |
| 248 | fprint_dummy_frames (struct ui_file *file) |
| 249 | { |
| 250 | struct dummy_frame *s; |
| 251 | for (s = dummy_frame_stack; s != NULL; s = s->next) |
| 252 | { |
| 253 | gdb_print_host_address (s, file); |
| 254 | fprintf_unfiltered (file, ":"); |
| 255 | fprintf_unfiltered (file, " id="); |
| 256 | fprint_frame_id (file, s->id); |
| 257 | fprintf_unfiltered (file, "\n"); |
| 258 | } |
| 259 | } |
| 260 | |
| 261 | static void |
| 262 | maintenance_print_dummy_frames (char *args, int from_tty) |
| 263 | { |
| 264 | if (args == NULL) |
| 265 | fprint_dummy_frames (gdb_stdout); |
| 266 | else |
| 267 | { |
| 268 | struct ui_file *file = gdb_fopen (args, "w"); |
| 269 | if (file == NULL) |
| 270 | perror_with_name (_("maintenance print dummy-frames")); |
| 271 | fprint_dummy_frames (file); |
| 272 | ui_file_delete (file); |
| 273 | } |
| 274 | } |
| 275 | |
| 276 | extern void _initialize_dummy_frame (void); |
| 277 | |
| 278 | void |
| 279 | _initialize_dummy_frame (void) |
| 280 | { |
| 281 | add_cmd ("dummy-frames", class_maintenance, maintenance_print_dummy_frames, |
| 282 | _("Print the contents of the internal dummy-frame stack."), |
| 283 | &maintenanceprintlist); |
| 284 | |
| 285 | observer_attach_inferior_created (cleanup_dummy_frames); |
| 286 | } |