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[binutils-gdb.git] / gdb / nat / x86-linux-dregs.c
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1 /* Low-level debug register code for GNU/Linux x86 (i386 and x86-64).
3 Copyright (C) 1999-2022 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/>. */
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"
28 /* Return the offset of REGNUM in the u_debugreg field of struct
29 user. */
31 static int
32 u_debugreg_offset (int regnum)
34 return (offsetof (struct user, u_debugreg)
35 + sizeof (((struct user *) 0)->u_debugreg[0]) * regnum);
38 /* Get debug register REGNUM value from the LWP specified by PTID. */
40 static unsigned long
41 x86_linux_dr_get (ptid_t ptid, int regnum)
43 int tid;
44 unsigned long value;
46 gdb_assert (ptid.lwp_p ());
47 tid = ptid.lwp ();
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"));
54 return value;
57 /* Set debug register REGNUM to VALUE in the LWP specified by PTID. */
59 static void
60 x86_linux_dr_set (ptid_t ptid, int regnum, unsigned long value)
62 int tid;
64 gdb_assert (ptid.lwp_p ());
65 tid = ptid.lwp ();
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"));
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. */
78 static int
79 update_debug_registers_callback (struct lwp_info *lwp)
81 lwp_set_debug_registers_changed (lwp, 1);
83 if (!lwp_is_stopped (lwp))
84 linux_stop_lwp (lwp);
86 /* Continue the iteration. */
87 return 0;
90 /* See nat/x86-linux-dregs.h. */
92 CORE_ADDR
93 x86_linux_dr_get_addr (int regnum)
95 gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);
97 return x86_linux_dr_get (current_lwp_ptid (), regnum);
100 /* See nat/x86-linux-dregs.h. */
102 void
103 x86_linux_dr_set_addr (int regnum, CORE_ADDR addr)
105 ptid_t pid_ptid = ptid_t (current_lwp_ptid ().pid ());
107 gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);
109 iterate_over_lwps (pid_ptid, update_debug_registers_callback);
112 /* See nat/x86-linux-dregs.h. */
114 unsigned long
115 x86_linux_dr_get_control (void)
117 return x86_linux_dr_get (current_lwp_ptid (), DR_CONTROL);
120 /* See nat/x86-linux-dregs.h. */
122 void
123 x86_linux_dr_set_control (unsigned long control)
125 ptid_t pid_ptid = ptid_t (current_lwp_ptid ().pid ());
127 iterate_over_lwps (pid_ptid, update_debug_registers_callback);
130 /* See nat/x86-linux-dregs.h. */
132 unsigned long
133 x86_linux_dr_get_status (void)
135 return x86_linux_dr_get (current_lwp_ptid (), DR_STATUS);
138 /* See nat/x86-linux-dregs.h. */
140 void
141 x86_linux_update_debug_registers (struct lwp_info *lwp)
143 ptid_t ptid = ptid_of_lwp (lwp);
144 int clear_status = 0;
146 gdb_assert (lwp_is_stopped (lwp));
148 if (lwp_debug_registers_changed (lwp))
150 struct x86_debug_reg_state *state
151 = x86_debug_reg_state (ptid.pid ());
152 int i;
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);
162 ALL_DEBUG_ADDRESS_REGISTERS (i)
163 if (state->dr_ref_count[i] > 0)
165 x86_linux_dr_set (ptid, i, state->dr_mirror[i]);
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;
173 /* If DR_CONTROL is supposed to be zero then it's already set. */
174 if (state->dr_control_mirror != 0)
175 x86_linux_dr_set (ptid, DR_CONTROL, state->dr_control_mirror);
177 lwp_set_debug_registers_changed (lwp, 0);
180 if (clear_status
181 || lwp_stop_reason (lwp) == TARGET_STOPPED_BY_WATCHPOINT)
182 x86_linux_dr_set (ptid, DR_STATUS, 0);