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x86-linux-dregs.c
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1 /* Low-level debug register code for GNU/Linux x86 (i386 and x86-64).
2 
3  Copyright (C) 1999-2015 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 "common-defs.h"
21 #include <sys/ptrace.h>
22 #include <sys/user.h>
23 #include "target/waitstatus.h"
24 #include "nat/x86-linux.h"
25 #include "nat/x86-dregs.h"
26 #include "nat/x86-linux-dregs.h"
27 
28 /* Return the offset of REGNUM in the u_debugreg field of struct
29  user. */
30 
31 static int
33 {
34  return (offsetof (struct user, u_debugreg)
35  + sizeof (((struct user *) 0)->u_debugreg[0]) * regnum);
36 }
37 
38 /* Get debug register REGNUM value from the LWP specified by PTID. */
39 
40 static unsigned long
42 {
43  int tid;
44  unsigned long value;
45 
46  gdb_assert (ptid_lwp_p (ptid));
47  tid = ptid_get_lwp (ptid);
48 
49  errno = 0;
50  value = ptrace (PTRACE_PEEKUSER, tid, u_debugreg_offset (regnum), 0);
51  if (errno != 0)
52  perror_with_name (_("Couldn't read debug register"));
53 
54  return value;
55 }
56 
57 /* Set debug register REGNUM to VALUE in the LWP specified by PTID. */
58 
59 static void
60 x86_linux_dr_set (ptid_t ptid, int regnum, unsigned long value)
61 {
62  int tid;
63 
64  gdb_assert (ptid_lwp_p (ptid));
65  tid = ptid_get_lwp (ptid);
66 
67  errno = 0;
68  ptrace (PTRACE_POKEUSER, tid, u_debugreg_offset (regnum), value);
69  if (errno != 0)
70  perror_with_name (_("Couldn't write debug register"));
71 }
72 
73 /* Callback for iterate_over_lwps. Mark that our local mirror of
74  LWP's debug registers has been changed, and cause LWP to stop if
75  it isn't already. Values are written from our local mirror to
76  the actual debug registers immediately prior to LWP resuming. */
77 
78 static int
79 update_debug_registers_callback (struct lwp_info *lwp, void *arg)
80 {
82 
83  if (!lwp_is_stopped (lwp))
84  linux_stop_lwp (lwp);
85 
86  /* Continue the iteration. */
87  return 0;
88 }
89 
90 /* See nat/x86-linux-dregs.h. */
91 
94 {
95  gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);
96 
97  return x86_linux_dr_get (current_lwp_ptid (), regnum);
98 }
99 
100 /* See nat/x86-linux-dregs.h. */
101 
102 void
104 {
106 
107  gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);
108 
110 }
111 
112 /* See nat/x86-linux-dregs.h. */
113 
114 unsigned long
116 {
118 }
119 
120 /* See nat/x86-linux-dregs.h. */
121 
122 void
123 x86_linux_dr_set_control (unsigned long control)
124 {
126 
128 }
129 
130 /* See nat/x86-linux-dregs.h. */
131 
132 unsigned long
134 {
136 }
137 
138 /* See nat/x86-linux-dregs.h. */
139 
140 void
142 {
143  ptid_t ptid = ptid_of_lwp (lwp);
144  int clear_status = 0;
145 
146  gdb_assert (lwp_is_stopped (lwp));
147 
148  if (lwp_debug_registers_changed (lwp))
149  {
150  struct x86_debug_reg_state *state
152  int i;
153 
154  /* Prior to Linux kernel 2.6.33 commit
155  72f674d203cd230426437cdcf7dd6f681dad8b0d, setting DR0-3 to
156  a value that did not match what was enabled in DR_CONTROL
157  resulted in EINVAL. To avoid this we zero DR_CONTROL before
158  writing address registers, only writing DR_CONTROL's actual
159  value once all the addresses are in place. */
160  x86_linux_dr_set (ptid, DR_CONTROL, 0);
161 
163  if (state->dr_ref_count[i] > 0)
164  {
165  x86_linux_dr_set (ptid, i, state->dr_mirror[i]);
166 
167  /* If we're setting a watchpoint, any change the inferior
168  has made to its debug registers needs to be discarded
169  to avoid x86_stopped_data_address getting confused. */
170  clear_status = 1;
171  }
172 
173  /* If DR_CONTROL is supposed to be zero then it's already set. */
174  if (state->dr_control_mirror != 0)
176 
178  }
179 
180  if (clear_status
181  || lwp_stop_reason (lwp) == TARGET_STOPPED_BY_WATCHPOINT)
182  x86_linux_dr_set (ptid, DR_STATUS, 0);
183 }
ptid_t ptid_of_lwp(struct lwp_info *lwp)
Definition: linux-low.c:147
unsigned long x86_linux_dr_get_status(void)
void x86_linux_update_debug_registers(struct lwp_info *lwp)
bfd_vma CORE_ADDR
Definition: common-types.h:41
unsigned dr_control_mirror
Definition: x86-dregs.h:85
static int u_debugreg_offset(int regnum)
enum target_stop_reason lwp_stop_reason(struct lwp_info *lwp)
Definition: linux-low.c:180
regnum
#define _(String)
Definition: gdb_locale.h:40
void x86_linux_dr_set_control(unsigned long control)
static void x86_linux_dr_set(ptid_t ptid, int regnum, unsigned long value)
Definition: ptid.h:35
#define DR_FIRSTADDR
Definition: x86-dregs.h:69
int lwp_is_stopped(struct lwp_info *lwp)
Definition: linux-low.c:172
#define DR_STATUS
Definition: x86-dregs.h:72
struct x86_debug_reg_state * x86_debug_reg_state(pid_t pid)
int lwp_debug_registers_changed(struct lwp_info *lwp)
Definition: x86-linux.c:47
CORE_ADDR dr_mirror[DR_NADDR]
Definition: x86-dregs.h:84
ptid_t pid_to_ptid(int pid)
Definition: ptid.c:44
void lwp_set_debug_registers_changed(struct lwp_info *lwp, int value)
Definition: x86-linux.c:36
static int update_debug_registers_callback(struct lwp_info *lwp, void *arg)
#define gdb_assert(expr)
Definition: gdb_assert.h:33
void x86_linux_dr_set_addr(int regnum, CORE_ADDR addr)
static unsigned long x86_linux_dr_get(ptid_t ptid, int regnum)
#define errno
Definition: wincecompat.h:24
int ptid_get_pid(ptid_t ptid)
Definition: ptid.c:52
CORE_ADDR x86_linux_dr_get_addr(int regnum)
#define DR_CONTROL
Definition: x86-dregs.h:73
int dr_ref_count[DR_NADDR]
Definition: x86-dregs.h:88
ptid_t current_lwp_ptid(void)
Definition: linux-low.c:6814
#define ALL_DEBUG_ADDRESS_REGISTERS(i)
Definition: x86-dregs.h:92
unsigned long x86_linux_dr_get_control(void)
void perror_with_name(const char *string)
Definition: utils.c:57
long ptid_get_lwp(ptid_t ptid)
Definition: ptid.c:60
struct lwp_info * iterate_over_lwps(ptid_t filter, iterate_over_lwps_ftype callback, void *data)
Definition: linux-low.c:1599
void linux_stop_lwp(struct lwp_info *lwp)
Definition: linux-low.c:3467
int ptid_lwp_p(ptid_t ptid)
Definition: ptid.c:98
#define DR_LASTADDR
Definition: x86-dregs.h:70