GDB (xrefs)
/tmp/gdb-7.10/gdb/x86-nat.c
Go to the documentation of this file.
1 /* Native-dependent code for x86 (i386 and x86-64).
2 
3  Copyright (C) 2001-2015 Free Software Foundation, Inc.
4 
5  This file is part of GDB.
6 
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.
11 
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.
16 
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/>. */
19 
20 #include "defs.h"
21 #include "x86-nat.h"
22 #include "gdbcmd.h"
23 #include "inferior.h"
24 
25 /* Support for hardware watchpoints and breakpoints using the x86
26  debug registers.
27 
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.
32 
33  The functions below implement debug registers sharing by reference
34  counts, and allow to watch regions up to 16 bytes long. */
35 
36 /* Low-level function vector. */
38 
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,
42  checkpoints). */
43 
45 {
46  /* Linked list. */
48 
49  /* The process identifier. */
50  pid_t pid;
51 
52  /* Copy of x86 hardware debug registers. */
54 };
55 
56 static struct x86_process_info *x86_process_list = NULL;
57 
58 /* Find process data for process PID. */
59 
60 static struct x86_process_info *
62 {
63  struct x86_process_info *proc;
64 
65  for (proc = x86_process_list; proc; proc = proc->next)
66  if (proc->pid == pid)
67  return proc;
68 
69  return NULL;
70 }
71 
72 /* Add process data for process PID. Returns newly allocated info
73  object. */
74 
75 static struct x86_process_info *
77 {
78  struct x86_process_info *proc;
79 
80  proc = xcalloc (1, sizeof (*proc));
81  proc->pid = pid;
82 
83  proc->next = x86_process_list;
84  x86_process_list = proc;
85 
86  return proc;
87 }
88 
89 /* Get data specific info for process PID, creating it if necessary.
90  Never returns NULL. */
91 
92 static struct x86_process_info *
94 {
95  struct x86_process_info *proc;
96 
97  proc = x86_find_process_pid (pid);
98  if (proc == NULL)
99  proc = x86_add_process (pid);
100 
101  return proc;
102 }
103 
104 /* Get debug registers state for process PID. */
105 
106 struct x86_debug_reg_state *
108 {
109  return &x86_process_info_get (pid)->state;
110 }
111 
112 /* See declaration in i386-nat.h. */
113 
114 void
116 {
117  struct x86_process_info *proc, **proc_link;
118 
119  proc = x86_process_list;
120  proc_link = &x86_process_list;
121 
122  while (proc != NULL)
123  {
124  if (proc->pid == pid)
125  {
126  *proc_link = proc->next;
127 
128  xfree (proc);
129  return;
130  }
131 
132  proc_link = &proc->next;
133  proc = *proc_link;
134  }
135 }
136 
137 /* Clear the reference counts and forget everything we knew about the
138  debug registers. */
139 
140 void
142 {
143  /* Starting from scratch has the same effect. */
145 }
146 
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. */
150 
151 static int
153  CORE_ADDR addr, int len, int type,
154  struct expression *cond)
155 {
156  struct x86_debug_reg_state *state
158 
159  return x86_dr_insert_watchpoint (state, type, addr, len);
160 }
161 
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. */
165 static int
167  CORE_ADDR addr, int len, int type,
168  struct expression *cond)
169 {
170  struct x86_debug_reg_state *state
172 
173  return x86_dr_remove_watchpoint (state, type, addr, len);
174 }
175 
176 /* Return non-zero if we can watch a memory region that starts at
177  address ADDR and whose length is LEN bytes. */
178 
179 static int
181  CORE_ADDR addr, int len)
182 {
183  struct x86_debug_reg_state *state
185 
186  return x86_dr_region_ok_for_watchpoint (state, addr, len);
187 }
188 
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. */
192 
193 static int
195 {
196  struct x86_debug_reg_state *state
198 
199  return x86_dr_stopped_data_address (state, addr_p);
200 }
201 
202 /* Return non-zero if the inferior has some watchpoint that triggered.
203  Otherwise return zero. */
204 
205 static int
207 {
208  struct x86_debug_reg_state *state
210 
211  return x86_dr_stopped_by_watchpoint (state);
212 }
213 
214 /* Insert a hardware-assisted breakpoint at BP_TGT->reqstd_address.
215  Return 0 on success, EBUSY on failure. */
216 
217 static int
219  struct bp_target_info *bp_tgt)
220 {
221  struct x86_debug_reg_state *state
223 
224  bp_tgt->placed_address = bp_tgt->reqstd_address;
225  return x86_dr_insert_watchpoint (state, hw_execute,
226  bp_tgt->placed_address, 1) ? EBUSY : 0;
227 }
228 
229 /* Remove a hardware-assisted breakpoint at BP_TGT->placed_address.
230  Return 0 on success, -1 on failure. */
231 
232 static int
234  struct bp_target_info *bp_tgt)
235 {
236  struct x86_debug_reg_state *state
238 
239  return x86_dr_remove_watchpoint (state, hw_execute,
240  bp_tgt->placed_address, 1);
241 }
242 
243 /* Returns the number of hardware watchpoints of type TYPE that we can
244  set. Value is positive if we can set CNT watchpoints, zero if
245  setting watchpoints of type TYPE is not supported, and negative if
246  CNT is more than the maximum number of watchpoints of type TYPE
247  that we can support. TYPE is one of bp_hardware_watchpoint,
248  bp_read_watchpoint, bp_write_watchpoint, or bp_hardware_breakpoint.
249  CNT is the number of such watchpoints used so far (including this
250  one). OTHERTYPE is non-zero if other types of watchpoints are
251  currently enabled.
252 
253  We always return 1 here because we don't have enough information
254  about possible overlap of addresses that they want to watch. As an
255  extreme example, consider the case where all the watchpoints watch
256  the same address and the same region length: then we can handle a
257  virtually unlimited number of watchpoints, due to debug register
258  sharing implemented via reference counts in i386-nat.c. */
259 
260 static int
262  int type, int cnt, int othertype)
263 {
264  return 1;
265 }
266 
267 static void
269 {
270  /* A maintenance command to enable printing the internal DRi mirror
271  variables. */
272  add_setshow_boolean_cmd ("show-debug-regs", class_maintenance,
273  &show_debug_regs, _("\
274 Set whether to show variables that mirror the x86 debug registers."), _("\
275 Show whether to show variables that mirror the x86 debug registers."), _("\
276 Use \"on\" to enable, \"off\" to disable.\n\
277 If enabled, the debug registers values are shown when GDB inserts\n\
278 or removes a hardware breakpoint or watchpoint, and when the inferior\n\
279 triggers a breakpoint or watchpoint."),
280  NULL,
281  NULL,
284 }
285 
286 /* There are only two global functions left. */
287 
288 void
290 {
291  /* After a watchpoint trap, the PC points to the instruction after the
292  one that caused the trap. Therefore we don't need to step over it.
293  But we do need to reset the status register to avoid another trap. */
295 
304 }
305 
306 void
308 {
309  /* This function should be called only once for each native target. */
311  gdb_assert (len == 4 || len == 8);
314 }
CORE_ADDR reqstd_address
Definition: breakpoint.h:235
static int x86_can_use_hw_breakpoint(struct target_ops *self, int type, int cnt, int othertype)
Definition: x86-nat.c:261
bfd_vma CORE_ADDR
Definition: common-types.h:41
static struct x86_process_info * x86_find_process_pid(pid_t pid)
Definition: x86-nat.c:61
void xfree(void *)
Definition: common-utils.c:97
struct x86_process_info * next
Definition: x86-nat.c:47
static int x86_remove_hw_breakpoint(struct target_ops *self, struct gdbarch *gdbarch, struct bp_target_info *bp_tgt)
Definition: x86-nat.c:233
int x86_dr_remove_watchpoint(struct x86_debug_reg_state *state, enum target_hw_bp_type type, CORE_ADDR addr, int len)
Definition: x86-dregs.c:516
int(* to_region_ok_for_hw_watchpoint)(struct target_ops *, CORE_ADDR, int) TARGET_DEFAULT_FUNC(default_region_ok_for_hw_watchpoint)
Definition: target.h:554
#define _(String)
Definition: gdb_locale.h:40
int x86_dr_stopped_data_address(struct x86_debug_reg_state *state, CORE_ADDR *addr_p)
Definition: x86-dregs.c:571
struct cmd_list_element * maintenance_set_cmdlist
Definition: maint.c:646
int x86_dr_insert_watchpoint(struct x86_debug_reg_state *state, enum target_hw_bp_type type, CORE_ADDR addr, int len)
Definition: x86-dregs.c:474
struct x86_debug_reg_state state
Definition: x86-nat.c:53
int x86_dr_region_ok_for_watchpoint(struct x86_debug_reg_state *state, CORE_ADDR addr, int len)
Definition: x86-dregs.c:554
int(* to_insert_watchpoint)(struct target_ops *, CORE_ADDR, int, int, struct expression *) TARGET_DEFAULT_RETURN(-1)
Definition: target.h:532
Definition: gnu-nat.h:42
static int x86_stopped_by_watchpoint(struct target_ops *ops)
Definition: x86-nat.c:206
static struct x86_process_info * x86_process_list
Definition: x86-nat.c:56
int(* to_remove_watchpoint)(struct target_ops *, CORE_ADDR, int, int, struct expression *) TARGET_DEFAULT_RETURN(-1)
Definition: target.h:529
static struct x86_process_info * x86_add_process(pid_t pid)
Definition: x86-nat.c:76
int show_debug_regs
Definition: common-debug.c:25
Definition: gdbtypes.h:749
static int x86_stopped_data_address(struct target_ops *ops, CORE_ADDR *addr_p)
Definition: x86-nat.c:194
#define gdb_assert(expr)
Definition: gdb_assert.h:33
struct x86_debug_reg_state * x86_debug_reg_state(pid_t pid)
Definition: x86-nat.c:107
CORE_ADDR placed_address
Definition: breakpoint.h:232
int x86_dr_stopped_by_watchpoint(struct x86_debug_reg_state *state)
Definition: x86-dregs.c:651
int(* to_insert_hw_breakpoint)(struct target_ops *, struct gdbarch *, struct bp_target_info *) TARGET_DEFAULT_RETURN(-1)
Definition: target.h:520
int ptid_get_pid(ptid_t ptid)
Definition: ptid.c:52
struct x86_dr_low_type x86_dr_low
Definition: x86-nat.c:37
static struct x86_process_info * x86_process_info_get(pid_t pid)
Definition: x86-nat.c:93
int(* to_remove_hw_breakpoint)(struct target_ops *, struct gdbarch *, struct bp_target_info *) TARGET_DEFAULT_RETURN(-1)
Definition: target.h:523
void x86_forget_process(pid_t pid)
Definition: x86-nat.c:115
int(* to_can_use_hw_breakpoint)(struct target_ops *, int, int, int) TARGET_DEFAULT_RETURN(0)
Definition: target.h:516
static int x86_region_ok_for_watchpoint(struct target_ops *self, CORE_ADDR addr, int len)
Definition: x86-nat.c:180
ptid_t inferior_ptid
Definition: infcmd.c:124
static int x86_insert_watchpoint(struct target_ops *self, CORE_ADDR addr, int len, int type, struct expression *cond)
Definition: x86-nat.c:152
static int x86_insert_hw_breakpoint(struct target_ops *self, struct gdbarch *gdbarch, struct bp_target_info *bp_tgt)
Definition: x86-nat.c:218
int(* to_stopped_by_watchpoint)(struct target_ops *) TARGET_DEFAULT_RETURN(0)
Definition: target.h:542
static void add_show_debug_regs_command(void)
Definition: x86-nat.c:268
static int x86_remove_watchpoint(struct target_ops *self, CORE_ADDR addr, int len, int type, struct expression *cond)
Definition: x86-nat.c:166
int to_have_continuable_watchpoint
Definition: target.h:545
void x86_set_debug_register_length(int len)
Definition: x86-nat.c:307
int debug_register_length
Definition: x86-dregs.h:63
void x86_use_watchpoints(struct target_ops *t)
Definition: x86-nat.c:289
int(* to_stopped_data_address)(struct target_ops *, CORE_ADDR *) TARGET_DEFAULT_RETURN(0)
Definition: target.h:546
void x86_cleanup_dregs(void)
Definition: x86-nat.c:141
PTR xcalloc(size_t number, size_t size)
Definition: common-utils.c:71
struct cmd_list_element * maintenance_show_cmdlist
Definition: maint.c:647
mach_port_t mach_port_t name mach_port_t mach_port_t name error_t int int rusage_t pid_t pid
Definition: gnu-nat.c:1818
void add_setshow_boolean_cmd(const char *name, enum command_class theclass, int *var, const char *set_doc, const char *show_doc, const char *help_doc, cmd_sfunc_ftype *set_func, show_value_ftype *show_func, struct cmd_list_element **set_list, struct cmd_list_element **show_list)
Definition: cli-decode.c:541
const ULONGEST const LONGEST len
Definition: target.h:309