| 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 |
| 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 2 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, write to the Free Software |
| 21 | Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| 22 | Boston, MA 02110-1301, USA. */ |
| 23 | |
| 24 | |
| 25 | #include "defs.h" |
| 26 | #include "dummy-frame.h" |
| 27 | #include "regcache.h" |
| 28 | #include "frame.h" |
| 29 | #include "inferior.h" |
| 30 | #include "gdb_assert.h" |
| 31 | #include "frame-unwind.h" |
| 32 | #include "command.h" |
| 33 | #include "gdbcmd.h" |
| 34 | #include "gdb_string.h" |
| 35 | |
| 36 | /* Dummy frame. This saves the processor state just prior to setting |
| 37 | up the inferior function call. Older targets save the registers |
| 38 | on the target stack (but that really slows down function calls). */ |
| 39 | |
| 40 | struct dummy_frame |
| 41 | { |
| 42 | struct dummy_frame *next; |
| 43 | /* This frame's ID. Must match the value returned by |
| 44 | gdbarch_unwind_dummy_id. */ |
| 45 | struct frame_id id; |
| 46 | /* The caller's regcache. */ |
| 47 | struct regcache *regcache; |
| 48 | }; |
| 49 | |
| 50 | static struct dummy_frame *dummy_frame_stack = NULL; |
| 51 | |
| 52 | /* Function: deprecated_pc_in_call_dummy (pc) |
| 53 | |
| 54 | Return non-zero if the PC falls in a dummy frame created by gdb for |
| 55 | an inferior call. The code below which allows gdbarch_decr_pc_after_break |
| 56 | is for infrun.c, which may give the function a PC without that |
| 57 | subtracted out. |
| 58 | |
| 59 | FIXME: cagney/2002-11-23: This is silly. Surely "infrun.c" can |
| 60 | figure out what the real PC (as in the resume address) is BEFORE |
| 61 | calling this function. |
| 62 | |
| 63 | NOTE: cagney/2004-08-02: I'm pretty sure that, with the introduction of |
| 64 | infrun.c:adjust_pc_after_break (thanks), this function is now |
| 65 | always called with a correctly adjusted PC! |
| 66 | |
| 67 | NOTE: cagney/2004-08-02: Code should not need to call this. */ |
| 68 | |
| 69 | int |
| 70 | deprecated_pc_in_call_dummy (CORE_ADDR pc) |
| 71 | { |
| 72 | struct dummy_frame *dummyframe; |
| 73 | for (dummyframe = dummy_frame_stack; |
| 74 | dummyframe != NULL; |
| 75 | dummyframe = dummyframe->next) |
| 76 | { |
| 77 | if ((pc >= dummyframe->id.code_addr) |
| 78 | && (pc <= dummyframe->id.code_addr |
| 79 | + gdbarch_decr_pc_after_break (current_gdbarch))) |
| 80 | return 1; |
| 81 | } |
| 82 | return 0; |
| 83 | } |
| 84 | |
| 85 | /* Push the caller's state, along with the dummy frame info, onto a |
| 86 | dummy-frame stack. */ |
| 87 | |
| 88 | void |
| 89 | dummy_frame_push (struct regcache *caller_regcache, |
| 90 | const struct frame_id *dummy_id) |
| 91 | { |
| 92 | struct dummy_frame *dummy_frame; |
| 93 | |
| 94 | /* Check to see if there are stale dummy frames, perhaps left over |
| 95 | from when a longjump took us out of a function that was called by |
| 96 | the debugger. */ |
| 97 | dummy_frame = dummy_frame_stack; |
| 98 | while (dummy_frame) |
| 99 | /* FIXME: cagney/2004-08-02: Should just test IDs. */ |
| 100 | if (frame_id_inner (dummy_frame->id, (*dummy_id))) |
| 101 | /* Stale -- destroy! */ |
| 102 | { |
| 103 | dummy_frame_stack = dummy_frame->next; |
| 104 | regcache_xfree (dummy_frame->regcache); |
| 105 | xfree (dummy_frame); |
| 106 | dummy_frame = dummy_frame_stack; |
| 107 | } |
| 108 | else |
| 109 | dummy_frame = dummy_frame->next; |
| 110 | |
| 111 | dummy_frame = XZALLOC (struct dummy_frame); |
| 112 | dummy_frame->regcache = caller_regcache; |
| 113 | dummy_frame->id = (*dummy_id); |
| 114 | dummy_frame->next = dummy_frame_stack; |
| 115 | dummy_frame_stack = dummy_frame; |
| 116 | } |
| 117 | |
| 118 | /* Return the dummy frame cache, it contains both the ID, and a |
| 119 | pointer to the regcache. */ |
| 120 | struct dummy_frame_cache |
| 121 | { |
| 122 | struct frame_id this_id; |
| 123 | struct regcache *prev_regcache; |
| 124 | }; |
| 125 | |
| 126 | int |
| 127 | dummy_frame_sniffer (const struct frame_unwind *self, |
| 128 | struct frame_info *next_frame, |
| 129 | void **this_prologue_cache) |
| 130 | { |
| 131 | struct dummy_frame *dummyframe; |
| 132 | struct frame_id this_id; |
| 133 | |
| 134 | /* When unwinding a normal frame, the stack structure is determined |
| 135 | by analyzing the frame's function's code (be it using brute force |
| 136 | prologue analysis, or the dwarf2 CFI). In the case of a dummy |
| 137 | frame, that simply isn't possible. The PC is either the program |
| 138 | entry point, or some random address on the stack. Trying to use |
| 139 | that PC to apply standard frame ID unwind techniques is just |
| 140 | asking for trouble. */ |
| 141 | |
| 142 | /* Don't bother unles there is at least one dummy frame. */ |
| 143 | if (dummy_frame_stack != NULL) |
| 144 | { |
| 145 | /* Use an architecture specific method to extract the prev's |
| 146 | dummy ID from the next frame. Note that this method uses |
| 147 | frame_register_unwind to obtain the register values needed to |
| 148 | determine the dummy frame's ID. */ |
| 149 | this_id = gdbarch_unwind_dummy_id (get_frame_arch (next_frame), |
| 150 | next_frame); |
| 151 | |
| 152 | /* Use that ID to find the corresponding cache entry. */ |
| 153 | for (dummyframe = dummy_frame_stack; |
| 154 | dummyframe != NULL; |
| 155 | dummyframe = dummyframe->next) |
| 156 | { |
| 157 | if (frame_id_eq (dummyframe->id, this_id)) |
| 158 | { |
| 159 | struct dummy_frame_cache *cache; |
| 160 | cache = FRAME_OBSTACK_ZALLOC (struct dummy_frame_cache); |
| 161 | cache->prev_regcache = dummyframe->regcache; |
| 162 | cache->this_id = this_id; |
| 163 | (*this_prologue_cache) = cache; |
| 164 | return 1; |
| 165 | } |
| 166 | } |
| 167 | } |
| 168 | return 0; |
| 169 | } |
| 170 | |
| 171 | /* Given a call-dummy dummy-frame, return the registers. Here the |
| 172 | register value is taken from the local copy of the register buffer. */ |
| 173 | |
| 174 | static void |
| 175 | dummy_frame_prev_register (struct frame_info *next_frame, |
| 176 | void **this_prologue_cache, |
| 177 | int regnum, int *optimized, |
| 178 | enum lval_type *lvalp, CORE_ADDR *addrp, |
| 179 | int *realnum, gdb_byte *bufferp) |
| 180 | { |
| 181 | /* The dummy-frame sniffer always fills in the cache. */ |
| 182 | struct dummy_frame_cache *cache = (*this_prologue_cache); |
| 183 | gdb_assert (cache != NULL); |
| 184 | |
| 185 | /* Describe the register's location. Generic dummy frames always |
| 186 | have the register value in an ``expression''. */ |
| 187 | *optimized = 0; |
| 188 | *lvalp = not_lval; |
| 189 | *addrp = 0; |
| 190 | *realnum = -1; |
| 191 | |
| 192 | /* If needed, find and return the value of the register. */ |
| 193 | if (bufferp != NULL) |
| 194 | { |
| 195 | /* Return the actual value. */ |
| 196 | /* Use the regcache_cooked_read() method so that it, on the fly, |
| 197 | constructs either a raw or pseudo register from the raw |
| 198 | register cache. */ |
| 199 | regcache_cooked_read (cache->prev_regcache, regnum, bufferp); |
| 200 | } |
| 201 | } |
| 202 | |
| 203 | /* Assuming that THIS frame is a dummy (remember, the NEXT and not |
| 204 | THIS frame is passed in), return the ID of THIS frame. That ID is |
| 205 | determined by examining the NEXT frame's unwound registers using |
| 206 | the method unwind_dummy_id(). As a side effect, THIS dummy frame's |
| 207 | dummy cache is located and and saved in THIS_PROLOGUE_CACHE. */ |
| 208 | |
| 209 | static void |
| 210 | dummy_frame_this_id (struct frame_info *next_frame, |
| 211 | void **this_prologue_cache, |
| 212 | struct frame_id *this_id) |
| 213 | { |
| 214 | /* The dummy-frame sniffer always fills in the cache. */ |
| 215 | struct dummy_frame_cache *cache = (*this_prologue_cache); |
| 216 | gdb_assert (cache != NULL); |
| 217 | (*this_id) = cache->this_id; |
| 218 | } |
| 219 | |
| 220 | static const struct frame_unwind dummy_frame_unwinder = |
| 221 | { |
| 222 | DUMMY_FRAME, |
| 223 | dummy_frame_this_id, |
| 224 | dummy_frame_prev_register, |
| 225 | NULL, |
| 226 | dummy_frame_sniffer, |
| 227 | }; |
| 228 | |
| 229 | const struct frame_unwind *const dummy_frame_unwind = { |
| 230 | &dummy_frame_unwinder |
| 231 | }; |
| 232 | |
| 233 | static void |
| 234 | fprint_dummy_frames (struct ui_file *file) |
| 235 | { |
| 236 | struct dummy_frame *s; |
| 237 | for (s = dummy_frame_stack; s != NULL; s = s->next) |
| 238 | { |
| 239 | gdb_print_host_address (s, file); |
| 240 | fprintf_unfiltered (file, ":"); |
| 241 | fprintf_unfiltered (file, " id="); |
| 242 | fprint_frame_id (file, s->id); |
| 243 | fprintf_unfiltered (file, "\n"); |
| 244 | } |
| 245 | } |
| 246 | |
| 247 | static void |
| 248 | maintenance_print_dummy_frames (char *args, int from_tty) |
| 249 | { |
| 250 | if (args == NULL) |
| 251 | fprint_dummy_frames (gdb_stdout); |
| 252 | else |
| 253 | { |
| 254 | struct ui_file *file = gdb_fopen (args, "w"); |
| 255 | if (file == NULL) |
| 256 | perror_with_name (_("maintenance print dummy-frames")); |
| 257 | fprint_dummy_frames (file); |
| 258 | ui_file_delete (file); |
| 259 | } |
| 260 | } |
| 261 | |
| 262 | extern void _initialize_dummy_frame (void); |
| 263 | |
| 264 | void |
| 265 | _initialize_dummy_frame (void) |
| 266 | { |
| 267 | add_cmd ("dummy-frames", class_maintenance, maintenance_print_dummy_frames, |
| 268 | _("Print the contents of the internal dummy-frame stack."), |
| 269 | &maintenanceprintlist); |
| 270 | |
| 271 | } |