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 = XCNEW (struct x86_process_info);
81 proc->next = x86_process_list;
82 x86_process_list = proc;
87 /* Get data specific info for process PID, creating it if necessary.
88 Never returns NULL. */
90 static struct x86_process_info *
91 x86_process_info_get (pid_t pid)
93 struct x86_process_info *proc;
95 proc = x86_find_process_pid (pid);
97 proc = x86_add_process (pid);
102 /* Get debug registers state for process PID. */
104 struct x86_debug_reg_state *
105 x86_debug_reg_state (pid_t pid)
107 return &x86_process_info_get (pid)->state;
110 /* See declaration in x86-nat.h. */
113 x86_forget_process (pid_t pid)
115 struct x86_process_info *proc, **proc_link;
117 proc = x86_process_list;
118 proc_link = &x86_process_list;
122 if (proc->pid == pid)
124 *proc_link = proc->next;
130 proc_link = &proc->next;
135 /* Clear the reference counts and forget everything we knew about the
139 x86_cleanup_dregs (void)
141 /* Starting from scratch has the same effect. */
142 x86_forget_process (ptid_get_pid (inferior_ptid));
145 /* Insert a watchpoint to watch a memory region which starts at
146 address ADDR and whose length is LEN bytes. Watch memory accesses
147 of the type TYPE. Return 0 on success, -1 on failure. */
150 x86_insert_watchpoint (struct target_ops *self, CORE_ADDR addr, int len,
151 enum target_hw_bp_type type, struct expression *cond)
153 struct x86_debug_reg_state *state
154 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
156 return x86_dr_insert_watchpoint (state, type, addr, len);
159 /* Remove a watchpoint that watched the memory region which starts at
160 address ADDR, whose length is LEN bytes, and for accesses of the
161 type TYPE. Return 0 on success, -1 on failure. */
163 x86_remove_watchpoint (struct target_ops *self, CORE_ADDR addr, int len,
164 enum target_hw_bp_type type, struct expression *cond)
166 struct x86_debug_reg_state *state
167 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
169 return x86_dr_remove_watchpoint (state, type, addr, len);
172 /* Return non-zero if we can watch a memory region that starts at
173 address ADDR and whose length is LEN bytes. */
176 x86_region_ok_for_watchpoint (struct target_ops *self,
177 CORE_ADDR addr, int len)
179 struct x86_debug_reg_state *state
180 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
182 return x86_dr_region_ok_for_watchpoint (state, addr, len);
185 /* If the inferior has some break/watchpoint that triggered, set the
186 address associated with that break/watchpoint and return non-zero.
187 Otherwise, return zero. */
190 x86_stopped_data_address (struct target_ops *ops, CORE_ADDR *addr_p)
192 struct x86_debug_reg_state *state
193 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
195 return x86_dr_stopped_data_address (state, addr_p);
198 /* Return non-zero if the inferior has some watchpoint that triggered.
199 Otherwise return zero. */
202 x86_stopped_by_watchpoint (struct target_ops *ops)
204 struct x86_debug_reg_state *state
205 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
207 return x86_dr_stopped_by_watchpoint (state);
210 /* Insert a hardware-assisted breakpoint at BP_TGT->reqstd_address.
211 Return 0 on success, EBUSY on failure. */
214 x86_insert_hw_breakpoint (struct target_ops *self, struct gdbarch *gdbarch,
215 struct bp_target_info *bp_tgt)
217 struct x86_debug_reg_state *state
218 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
220 bp_tgt->placed_address = bp_tgt->reqstd_address;
221 return x86_dr_insert_watchpoint (state, hw_execute,
222 bp_tgt->placed_address, 1) ? EBUSY : 0;
225 /* Remove a hardware-assisted breakpoint at BP_TGT->placed_address.
226 Return 0 on success, -1 on failure. */
229 x86_remove_hw_breakpoint (struct target_ops *self, struct gdbarch *gdbarch,
230 struct bp_target_info *bp_tgt)
232 struct x86_debug_reg_state *state
233 = x86_debug_reg_state (ptid_get_pid (inferior_ptid));
235 return x86_dr_remove_watchpoint (state, hw_execute,
236 bp_tgt->placed_address, 1);
239 /* Returns the number of hardware watchpoints of type TYPE that we can
240 set. Value is positive if we can set CNT watchpoints, zero if
241 setting watchpoints of type TYPE is not supported, and negative if
242 CNT is more than the maximum number of watchpoints of type TYPE
243 that we can support. TYPE is one of bp_hardware_watchpoint,
244 bp_read_watchpoint, bp_write_watchpoint, or bp_hardware_breakpoint.
245 CNT is the number of such watchpoints used so far (including this
246 one). OTHERTYPE is non-zero if other types of watchpoints are
249 We always return 1 here because we don't have enough information
250 about possible overlap of addresses that they want to watch. As an
251 extreme example, consider the case where all the watchpoints watch
252 the same address and the same region length: then we can handle a
253 virtually unlimited number of watchpoints, due to debug register
254 sharing implemented via reference counts in x86-nat.c. */
257 x86_can_use_hw_breakpoint (struct target_ops *self,
258 enum bptype type, int cnt, int othertype)
264 add_show_debug_regs_command (void)
266 /* A maintenance command to enable printing the internal DRi mirror
268 add_setshow_boolean_cmd ("show-debug-regs", class_maintenance,
269 &show_debug_regs, _("\
270 Set whether to show variables that mirror the x86 debug registers."), _("\
271 Show whether to show variables that mirror the x86 debug registers."), _("\
272 Use \"on\" to enable, \"off\" to disable.\n\
273 If enabled, the debug registers values are shown when GDB inserts\n\
274 or removes a hardware breakpoint or watchpoint, and when the inferior\n\
275 triggers a breakpoint or watchpoint."),
278 &maintenance_set_cmdlist,
279 &maintenance_show_cmdlist);
282 /* There are only two global functions left. */
285 x86_use_watchpoints (struct target_ops *t)
287 /* After a watchpoint trap, the PC points to the instruction after the
288 one that caused the trap. Therefore we don't need to step over it.
289 But we do need to reset the status register to avoid another trap. */
290 t->to_have_continuable_watchpoint = 1;
292 t->to_can_use_hw_breakpoint = x86_can_use_hw_breakpoint;
293 t->to_region_ok_for_hw_watchpoint = x86_region_ok_for_watchpoint;
294 t->to_stopped_by_watchpoint = x86_stopped_by_watchpoint;
295 t->to_stopped_data_address = x86_stopped_data_address;
296 t->to_insert_watchpoint = x86_insert_watchpoint;
297 t->to_remove_watchpoint = x86_remove_watchpoint;
298 t->to_insert_hw_breakpoint = x86_insert_hw_breakpoint;
299 t->to_remove_hw_breakpoint = x86_remove_hw_breakpoint;
303 x86_set_debug_register_length (int len)
305 /* This function should be called only once for each native target. */
306 gdb_assert (x86_dr_low.debug_register_length == 0);
307 gdb_assert (len == 4 || len == 8);
308 x86_dr_low.debug_register_length = len;
309 add_show_debug_regs_command ();