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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) 1999-2023 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 "gdbsupport/common-defs.h"
21#include "nat/gdb_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
31static 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
40static unsigned long
41x86_linux_dr_get (ptid_t ptid, int regnum)
42{
43 int tid;
44 unsigned long value;
45
46 gdb_assert (ptid.lwp_p ());
47 tid = ptid.lwp ();
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
59static void
60x86_linux_dr_set (ptid_t ptid, int regnum, unsigned long value)
61{
62 int tid;
63
64 gdb_assert (ptid.lwp_p ());
65 tid = ptid.lwp ();
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
78static int
79update_debug_registers_callback (struct lwp_info *lwp)
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
92CORE_ADDR
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
102void
103x86_linux_dr_set_addr (int regnum, CORE_ADDR addr)
104{
105 ptid_t pid_ptid = ptid_t (current_lwp_ptid ().pid ());
106
107 gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);
108
110}
111
112/* See nat/x86-linux-dregs.h. */
113
114unsigned long
119
120/* See nat/x86-linux-dregs.h. */
121
122void
123x86_linux_dr_set_control (unsigned long control)
124{
125 ptid_t pid_ptid = ptid_t (current_lwp_ptid ().pid ());
126
128}
129
130/* See nat/x86-linux-dregs.h. */
131
132unsigned long
137
138/* See nat/x86-linux-dregs.h. */
139
140void
142{
143 ptid_t ptid = ptid_of_lwp (lwp);
144 int clear_status = 0;
145
146 gdb_assert (lwp_is_stopped (lwp));
147
149 {
150 struct x86_debug_reg_state *state
151 = x86_debug_reg_state (ptid.pid ());
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}
#define ptrace(request, pid, addr, data)
Definition gdb_ptrace.h:141
ptid_t ptid_of_lwp(struct lwp_info *lwp)
void linux_stop_lwp(struct lwp_info *lwp)
ptid_t current_lwp_ptid(void)
struct lwp_info * iterate_over_lwps(ptid_t filter, gdb::function_view< iterate_over_lwps_ftype > callback)
int lwp_is_stopped(struct lwp_info *lwp)
enum target_stop_reason lwp_stop_reason(struct lwp_info *lwp)
unsigned dr_control_mirror
Definition x86-dregs.h:86
CORE_ADDR dr_mirror[DR_NADDR]
Definition x86-dregs.h:85
int dr_ref_count[DR_NADDR]
Definition x86-dregs.h:89
struct x86_debug_reg_state * x86_debug_reg_state(pid_t pid)
#define DR_STATUS
Definition x86-dregs.h:73
#define ALL_DEBUG_ADDRESS_REGISTERS(i)
Definition x86-dregs.h:93
#define DR_FIRSTADDR
Definition x86-dregs.h:70
#define DR_LASTADDR
Definition x86-dregs.h:71
#define DR_CONTROL
Definition x86-dregs.h:74
unsigned long x86_linux_dr_get_status(void)
unsigned long x86_linux_dr_get_control(void)
void x86_linux_dr_set_addr(int regnum, CORE_ADDR addr)
void x86_linux_update_debug_registers(struct lwp_info *lwp)
static void x86_linux_dr_set(ptid_t ptid, int regnum, unsigned long value)
CORE_ADDR x86_linux_dr_get_addr(int regnum)
static int u_debugreg_offset(int regnum)
static unsigned long x86_linux_dr_get(ptid_t ptid, int regnum)
void x86_linux_dr_set_control(unsigned long control)
static int update_debug_registers_callback(struct lwp_info *lwp)
void lwp_set_debug_registers_changed(struct lwp_info *lwp, int value)
Definition x86-linux.c:36
int lwp_debug_registers_changed(struct lwp_info *lwp)
Definition x86-linux.c:47