1 /* Native-dependent code for x86 (i386 and x86-64).
3 Copyright (C) 2001-2015 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, CORE_ADDR addr, int len,
153 enum target_hw_bp_type type, struct expression *cond)
155 struct x86_debug_reg_state *state
156 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
158 return x86_dr_insert_watchpoint (state, type, addr, len);
161 /* Remove a watchpoint that watched the memory region which starts at
162 address ADDR, whose length is LEN bytes, and for accesses of the
163 type TYPE. Return 0 on success, -1 on failure. */
165 x86_remove_watchpoint (struct target_ops *self, CORE_ADDR addr, int len,
166 enum target_hw_bp_type type, struct expression *cond)
168 struct x86_debug_reg_state *state
169 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
171 return x86_dr_remove_watchpoint (state, type, addr, len);
174 /* Return non-zero if we can watch a memory region that starts at
175 address ADDR and whose length is LEN bytes. */
178 x86_region_ok_for_watchpoint (struct target_ops *self,
179 CORE_ADDR addr, int len)
181 struct x86_debug_reg_state *state
182 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
184 return x86_dr_region_ok_for_watchpoint (state, addr, len);
187 /* If the inferior has some break/watchpoint that triggered, set the
188 address associated with that break/watchpoint and return non-zero.
189 Otherwise, return zero. */
192 x86_stopped_data_address (struct target_ops *ops, CORE_ADDR *addr_p)
194 struct x86_debug_reg_state *state
195 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
197 return x86_dr_stopped_data_address (state, addr_p);
200 /* Return non-zero if the inferior has some watchpoint that triggered.
201 Otherwise return zero. */
204 x86_stopped_by_watchpoint (struct target_ops *ops)
206 struct x86_debug_reg_state *state
207 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
209 return x86_dr_stopped_by_watchpoint (state);
212 /* Insert a hardware-assisted breakpoint at BP_TGT->reqstd_address.
213 Return 0 on success, EBUSY on failure. */
216 x86_insert_hw_breakpoint (struct target_ops *self, struct gdbarch *gdbarch,
217 struct bp_target_info *bp_tgt)
219 struct x86_debug_reg_state *state
220 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
222 bp_tgt->placed_address = bp_tgt->reqstd_address;
223 return x86_dr_insert_watchpoint (state, hw_execute,
224 bp_tgt->placed_address, 1) ? EBUSY : 0;
227 /* Remove a hardware-assisted breakpoint at BP_TGT->placed_address.
228 Return 0 on success, -1 on failure. */
231 x86_remove_hw_breakpoint (struct target_ops *self, struct gdbarch *gdbarch,
232 struct bp_target_info *bp_tgt)
234 struct x86_debug_reg_state *state
235 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
237 return x86_dr_remove_watchpoint (state, hw_execute,
238 bp_tgt->placed_address, 1);
241 /* Returns the number of hardware watchpoints of type TYPE that we can
242 set. Value is positive if we can set CNT watchpoints, zero if
243 setting watchpoints of type TYPE is not supported, and negative if
244 CNT is more than the maximum number of watchpoints of type TYPE
245 that we can support. TYPE is one of bp_hardware_watchpoint,
246 bp_read_watchpoint, bp_write_watchpoint, or bp_hardware_breakpoint.
247 CNT is the number of such watchpoints used so far (including this
248 one). OTHERTYPE is non-zero if other types of watchpoints are
251 We always return 1 here because we don't have enough information
252 about possible overlap of addresses that they want to watch. As an
253 extreme example, consider the case where all the watchpoints watch
254 the same address and the same region length: then we can handle a
255 virtually unlimited number of watchpoints, due to debug register
256 sharing implemented via reference counts in i386-nat.c. */
259 x86_can_use_hw_breakpoint (struct target_ops *self,
260 enum bptype type, int cnt, int othertype)
266 add_show_debug_regs_command (void)
268 /* A maintenance command to enable printing the internal DRi mirror
270 add_setshow_boolean_cmd ("show-debug-regs", class_maintenance,
271 &show_debug_regs, _("\
272 Set whether to show variables that mirror the x86 debug registers."), _("\
273 Show whether to show variables that mirror the x86 debug registers."), _("\
274 Use \"on\" to enable, \"off\" to disable.\n\
275 If enabled, the debug registers values are shown when GDB inserts\n\
276 or removes a hardware breakpoint or watchpoint, and when the inferior\n\
277 triggers a breakpoint or watchpoint."),
280 &maintenance_set_cmdlist,
281 &maintenance_show_cmdlist);
284 /* There are only two global functions left. */
287 x86_use_watchpoints (struct target_ops *t)
289 /* After a watchpoint trap, the PC points to the instruction after the
290 one that caused the trap. Therefore we don't need to step over it.
291 But we do need to reset the status register to avoid another trap. */
292 t->to_have_continuable_watchpoint = 1;
294 t->to_can_use_hw_breakpoint = x86_can_use_hw_breakpoint;
295 t->to_region_ok_for_hw_watchpoint = x86_region_ok_for_watchpoint;
296 t->to_stopped_by_watchpoint = x86_stopped_by_watchpoint;
297 t->to_stopped_data_address = x86_stopped_data_address;
298 t->to_insert_watchpoint = x86_insert_watchpoint;
299 t->to_remove_watchpoint = x86_remove_watchpoint;
300 t->to_insert_hw_breakpoint = x86_insert_hw_breakpoint;
301 t->to_remove_hw_breakpoint = x86_remove_hw_breakpoint;
305 x86_set_debug_register_length (int len)
307 /* This function should be called only once for each native target. */
308 gdb_assert (x86_dr_low.debug_register_length == 0);
309 gdb_assert (len == 4 || len == 8);
310 x86_dr_low.debug_register_length = len;
311 add_show_debug_regs_command ();