1 /* Native-dependent code for x86 (i386 and x86-64).
3 Copyright (C) 2001-2014 Free Software Foundation, Inc.
5 This file is part of GDB.
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.
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.
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/>. */
25 /* Support for hardware watchpoints and breakpoints using the x86
28 This provides several functions for inserting and removing
29 hardware-assisted breakpoints and watchpoints, testing if one or
30 more of the watchpoints triggered and at what address, checking
31 whether a given region can be watched, etc.
33 The functions below implement debug registers sharing by reference
34 counts, and allow to watch regions up to 16 bytes long. */
36 /* Low-level function vector. */
37 struct x86_dr_low_type x86_dr_low;
39 /* Per-process data. We don't bind this to a per-inferior registry
40 because of targets like x86 GNU/Linux that need to keep track of
41 processes that aren't bound to any inferior (e.g., fork children,
44 struct x86_process_info
47 struct x86_process_info *next;
49 /* The process identifier. */
52 /* Copy of x86 hardware debug registers. */
53 struct x86_debug_reg_state state;
56 static struct x86_process_info *x86_process_list = NULL;
58 /* Find process data for process PID. */
60 static struct x86_process_info *
61 x86_find_process_pid (pid_t pid)
63 struct x86_process_info *proc;
65 for (proc = x86_process_list; proc; proc = proc->next)
72 /* Add process data for process PID. Returns newly allocated info
75 static struct x86_process_info *
76 x86_add_process (pid_t pid)
78 struct x86_process_info *proc;
80 proc = xcalloc (1, sizeof (*proc));
83 proc->next = x86_process_list;
84 x86_process_list = proc;
89 /* Get data specific info for process PID, creating it if necessary.
90 Never returns NULL. */
92 static struct x86_process_info *
93 x86_process_info_get (pid_t pid)
95 struct x86_process_info *proc;
97 proc = x86_find_process_pid (pid);
99 proc = x86_add_process (pid);
104 /* Get debug registers state for process PID. */
106 struct x86_debug_reg_state *
107 x86_debug_reg_state (pid_t pid)
109 return &x86_process_info_get (pid)->state;
112 /* See declaration in i386-nat.h. */
115 x86_forget_process (pid_t pid)
117 struct x86_process_info *proc, **proc_link;
119 proc = x86_process_list;
120 proc_link = &x86_process_list;
124 if (proc->pid == pid)
126 *proc_link = proc->next;
132 proc_link = &proc->next;
137 /* Clear the reference counts and forget everything we knew about the
141 x86_cleanup_dregs (void)
143 /* Starting from scratch has the same effect. */
144 x86_forget_process (ptid_get_pid (inferior_ptid));
147 /* Insert a watchpoint to watch a memory region which starts at
148 address ADDR and whose length is LEN bytes. Watch memory accesses
149 of the type TYPE. Return 0 on success, -1 on failure. */
152 x86_insert_watchpoint (struct target_ops *self,
153 CORE_ADDR addr, int len, int type,
154 struct expression *cond)
156 struct x86_debug_reg_state *state
157 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
159 return x86_dr_insert_watchpoint (state, type, addr, len);
162 /* Remove a watchpoint that watched the memory region which starts at
163 address ADDR, whose length is LEN bytes, and for accesses of the
164 type TYPE. Return 0 on success, -1 on failure. */
166 x86_remove_watchpoint (struct target_ops *self,
167 CORE_ADDR addr, int len, int type,
168 struct expression *cond)
170 struct x86_debug_reg_state *state
171 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
173 return x86_dr_remove_watchpoint (state, type, addr, len);
176 /* Return non-zero if we can watch a memory region that starts at
177 address ADDR and whose length is LEN bytes. */
180 x86_region_ok_for_watchpoint (struct target_ops *self,
181 CORE_ADDR addr, int len)
183 struct x86_debug_reg_state *state
184 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
186 return x86_dr_region_ok_for_watchpoint (state, addr, len);
189 /* If the inferior has some break/watchpoint that triggered, set the
190 address associated with that break/watchpoint and return non-zero.
191 Otherwise, return zero. */
194 x86_stopped_data_address (struct target_ops *ops, CORE_ADDR *addr_p)
196 struct x86_debug_reg_state *state
197 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
199 return x86_dr_stopped_data_address (state, addr_p);
202 /* Return non-zero if the inferior has some watchpoint that triggered.
203 Otherwise return zero. */
206 x86_stopped_by_watchpoint (struct target_ops *ops)
208 struct x86_debug_reg_state *state
209 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
211 return x86_dr_stopped_by_watchpoint (state);
214 /* Insert a hardware-assisted breakpoint at BP_TGT->placed_address.
215 Return 0 on success, EBUSY on failure. */
218 x86_insert_hw_breakpoint (struct target_ops *self, struct gdbarch *gdbarch,
219 struct bp_target_info *bp_tgt)
221 struct x86_debug_reg_state *state
222 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
224 return x86_dr_insert_watchpoint (state, hw_execute,
225 bp_tgt->placed_address, 1) ? EBUSY : 0;
228 /* Remove a hardware-assisted breakpoint at BP_TGT->placed_address.
229 Return 0 on success, -1 on failure. */
232 x86_remove_hw_breakpoint (struct target_ops *self, struct gdbarch *gdbarch,
233 struct bp_target_info *bp_tgt)
235 struct x86_debug_reg_state *state
236 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
238 return x86_dr_remove_watchpoint (state, hw_execute,
239 bp_tgt->placed_address, 1);
242 /* Returns the number of hardware watchpoints of type TYPE that we can
243 set. Value is positive if we can set CNT watchpoints, zero if
244 setting watchpoints of type TYPE is not supported, and negative if
245 CNT is more than the maximum number of watchpoints of type TYPE
246 that we can support. TYPE is one of bp_hardware_watchpoint,
247 bp_read_watchpoint, bp_write_watchpoint, or bp_hardware_breakpoint.
248 CNT is the number of such watchpoints used so far (including this
249 one). OTHERTYPE is non-zero if other types of watchpoints are
252 We always return 1 here because we don't have enough information
253 about possible overlap of addresses that they want to watch. As an
254 extreme example, consider the case where all the watchpoints watch
255 the same address and the same region length: then we can handle a
256 virtually unlimited number of watchpoints, due to debug register
257 sharing implemented via reference counts in i386-nat.c. */
260 x86_can_use_hw_breakpoint (struct target_ops *self,
261 int type, int cnt, int othertype)
267 add_show_debug_regs_command (void)
269 /* A maintenance command to enable printing the internal DRi mirror
271 add_setshow_boolean_cmd ("show-debug-regs", class_maintenance,
272 &show_debug_regs, _("\
273 Set whether to show variables that mirror the x86 debug registers."), _("\
274 Show whether to show variables that mirror the x86 debug registers."), _("\
275 Use \"on\" to enable, \"off\" to disable.\n\
276 If enabled, the debug registers values are shown when GDB inserts\n\
277 or removes a hardware breakpoint or watchpoint, and when the inferior\n\
278 triggers a breakpoint or watchpoint."),
281 &maintenance_set_cmdlist,
282 &maintenance_show_cmdlist);
285 /* There are only two global functions left. */
288 x86_use_watchpoints (struct target_ops *t)
290 /* After a watchpoint trap, the PC points to the instruction after the
291 one that caused the trap. Therefore we don't need to step over it.
292 But we do need to reset the status register to avoid another trap. */
293 t->to_have_continuable_watchpoint = 1;
295 t->to_can_use_hw_breakpoint = x86_can_use_hw_breakpoint;
296 t->to_region_ok_for_hw_watchpoint = x86_region_ok_for_watchpoint;
297 t->to_stopped_by_watchpoint = x86_stopped_by_watchpoint;
298 t->to_stopped_data_address = x86_stopped_data_address;
299 t->to_insert_watchpoint = x86_insert_watchpoint;
300 t->to_remove_watchpoint = x86_remove_watchpoint;
301 t->to_insert_hw_breakpoint = x86_insert_hw_breakpoint;
302 t->to_remove_hw_breakpoint = x86_remove_hw_breakpoint;
306 x86_set_debug_register_length (int len)
308 /* This function should be called only once for each native target. */
309 gdb_assert (x86_dr_low.debug_register_length == 0);
310 gdb_assert (len == 4 || len == 8);
311 x86_dr_low.debug_register_length = len;
312 add_show_debug_regs_command ();