1 /* Native-dependent code for GNU/Linux x86 (i386 and x86-64).
3 Copyright (C) 1999-2023 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/>. */
22 #include "elf/common.h"
23 #include "gdb_proc_service.h"
24 #include "nat/gdb_ptrace.h"
26 #include <sys/procfs.h>
31 #include "i386-linux-nat.h"
33 #include "x86-linux-nat.h"
34 #include "i386-linux-tdep.h"
36 #include "amd64-linux-tdep.h"
38 #include "gdbsupport/x86-xstate.h"
39 #include "nat/x86-xstate.h"
40 #include "nat/linux-btrace.h"
41 #include "nat/linux-nat.h"
42 #include "nat/x86-linux.h"
43 #include "nat/x86-linux-dregs.h"
44 #include "nat/linux-ptrace.h"
46 /* linux_nat_target::low_new_fork implementation. */
49 x86_linux_nat_target::low_new_fork (struct lwp_info
*parent
, pid_t child_pid
)
52 struct x86_debug_reg_state
*parent_state
;
53 struct x86_debug_reg_state
*child_state
;
55 /* NULL means no watchpoint has ever been set in the parent. In
56 that case, there's nothing to do. */
57 if (parent
->arch_private
== NULL
)
60 /* Linux kernel before 2.6.33 commit
61 72f674d203cd230426437cdcf7dd6f681dad8b0d
62 will inherit hardware debug registers from parent
63 on fork/vfork/clone. Newer Linux kernels create such tasks with
64 zeroed debug registers.
66 GDB core assumes the child inherits the watchpoints/hw
67 breakpoints of the parent, and will remove them all from the
68 forked off process. Copy the debug registers mirrors into the
69 new process so that all breakpoints and watchpoints can be
70 removed together. The debug registers mirror will become zeroed
71 in the end before detaching the forked off process, thus making
72 this compatible with older Linux kernels too. */
74 parent_pid
= parent
->ptid
.pid ();
75 parent_state
= x86_debug_reg_state (parent_pid
);
76 child_state
= x86_debug_reg_state (child_pid
);
77 *child_state
= *parent_state
;
81 x86_linux_nat_target::~x86_linux_nat_target ()
85 /* Implement the virtual inf_ptrace_target::post_startup_inferior method. */
88 x86_linux_nat_target::post_startup_inferior (ptid_t ptid
)
91 linux_nat_target::post_startup_inferior (ptid
);
95 /* Value of CS segment register:
97 32bit process: 0x23 */
98 #define AMD64_LINUX_USER64_CS 0x33
100 /* Value of DS segment register:
103 #define AMD64_LINUX_X32_DS 0x2b
106 /* Get Linux/x86 target description from running target. */
108 const struct target_desc
*
109 x86_linux_nat_target::read_description ()
116 static uint64_t xcr0
;
117 uint64_t xcr0_features_bits
;
119 if (inferior_ptid
== null_ptid
)
120 return this->beneath ()->read_description ();
122 tid
= inferior_ptid
.pid ();
129 /* Get CS register. */
131 cs
= ptrace (PTRACE_PEEKUSER
, tid
,
132 offsetof (struct user_regs_struct
, cs
), 0);
134 perror_with_name (_("Couldn't get CS register"));
136 is_64bit
= cs
== AMD64_LINUX_USER64_CS
;
138 /* Get DS register. */
140 ds
= ptrace (PTRACE_PEEKUSER
, tid
,
141 offsetof (struct user_regs_struct
, ds
), 0);
143 perror_with_name (_("Couldn't get DS register"));
145 is_x32
= ds
== AMD64_LINUX_X32_DS
;
147 if (sizeof (void *) == 4 && is_64bit
&& !is_x32
)
148 error (_("Can't debug 64-bit process with 32-bit GDB"));
150 #elif HAVE_PTRACE_GETFPXREGS
151 if (have_ptrace_getfpxregs
== -1)
153 elf_fpxregset_t fpxregs
;
155 if (ptrace (PTRACE_GETFPXREGS
, tid
, 0, (int) &fpxregs
) < 0)
157 have_ptrace_getfpxregs
= 0;
158 have_ptrace_getregset
= TRIBOOL_FALSE
;
159 return i386_linux_read_description (X86_XSTATE_X87_MASK
);
164 if (have_ptrace_getregset
== TRIBOOL_UNKNOWN
)
166 uint64_t xstateregs
[(X86_XSTATE_SSE_SIZE
/ sizeof (uint64_t))];
169 iov
.iov_base
= xstateregs
;
170 iov
.iov_len
= sizeof (xstateregs
);
172 /* Check if PTRACE_GETREGSET works. */
173 if (ptrace (PTRACE_GETREGSET
, tid
,
174 (unsigned int) NT_X86_XSTATE
, &iov
) < 0)
175 have_ptrace_getregset
= TRIBOOL_FALSE
;
178 have_ptrace_getregset
= TRIBOOL_TRUE
;
180 /* Get XCR0 from XSAVE extended state. */
181 xcr0
= xstateregs
[(I386_LINUX_XSAVE_XCR0_OFFSET
182 / sizeof (uint64_t))];
184 m_xsave_layout
= x86_fetch_xsave_layout (xcr0
, x86_xsave_length ());
188 /* Check the native XCR0 only if PTRACE_GETREGSET is available. If
189 PTRACE_GETREGSET is not available then set xcr0_features_bits to
190 zero so that the "no-features" descriptions are returned by the
192 if (have_ptrace_getregset
== TRIBOOL_TRUE
)
193 xcr0_features_bits
= xcr0
& X86_XSTATE_ALL_MASK
;
195 xcr0_features_bits
= 0;
200 return amd64_linux_read_description (xcr0_features_bits
, is_x32
);
205 const struct target_desc
* tdesc
206 = i386_linux_read_description (xcr0_features_bits
);
209 tdesc
= i386_linux_read_description (X86_XSTATE_SSE_MASK
);
214 gdb_assert_not_reached ("failed to return tdesc");
218 /* Enable branch tracing. */
220 struct btrace_target_info
*
221 x86_linux_nat_target::enable_btrace (thread_info
*tp
,
222 const struct btrace_config
*conf
)
224 struct btrace_target_info
*tinfo
= nullptr;
225 ptid_t ptid
= tp
->ptid
;
228 tinfo
= linux_enable_btrace (ptid
, conf
);
230 catch (const gdb_exception_error
&exception
)
232 error (_("Could not enable branch tracing for %s: %s"),
233 target_pid_to_str (ptid
).c_str (), exception
.what ());
239 /* Disable branch tracing. */
242 x86_linux_nat_target::disable_btrace (struct btrace_target_info
*tinfo
)
244 enum btrace_error errcode
= linux_disable_btrace (tinfo
);
246 if (errcode
!= BTRACE_ERR_NONE
)
247 error (_("Could not disable branch tracing."));
250 /* Teardown branch tracing. */
253 x86_linux_nat_target::teardown_btrace (struct btrace_target_info
*tinfo
)
256 linux_disable_btrace (tinfo
);
260 x86_linux_nat_target::read_btrace (struct btrace_data
*data
,
261 struct btrace_target_info
*btinfo
,
262 enum btrace_read_type type
)
264 return linux_read_btrace (data
, btinfo
, type
);
267 /* See to_btrace_conf in target.h. */
269 const struct btrace_config
*
270 x86_linux_nat_target::btrace_conf (const struct btrace_target_info
*btinfo
)
272 return linux_btrace_conf (btinfo
);
277 /* Helper for ps_get_thread_area. Sets BASE_ADDR to a pointer to
278 the thread local storage (or its descriptor) and returns PS_OK
279 on success. Returns PS_ERR on failure. */
282 x86_linux_get_thread_area (pid_t pid
, void *addr
, unsigned int *base_addr
)
284 /* NOTE: cagney/2003-08-26: The definition of this buffer is found
285 in the kernel header <asm-i386/ldt.h>. It, after padding, is 4 x
286 4 byte integers in size: `entry_number', `base_addr', `limit',
287 and a bunch of status bits.
289 The values returned by this ptrace call should be part of the
290 regcache buffer, and ps_get_thread_area should channel its
291 request through the regcache. That way remote targets could
292 provide the value using the remote protocol and not this direct
295 Is this function needed? I'm guessing that the `base' is the
296 address of a descriptor that libthread_db uses to find the
297 thread local address base that GDB needs. Perhaps that
298 descriptor is defined by the ABI. Anyway, given that
299 libthread_db calls this function without prompting (gdb
300 requesting tls base) I guess it needs info in there anyway. */
301 unsigned int desc
[4];
303 /* This code assumes that "int" is 32 bits and that
304 GET_THREAD_AREA returns no more than 4 int values. */
305 gdb_assert (sizeof (int) == 4);
307 #ifndef PTRACE_GET_THREAD_AREA
308 #define PTRACE_GET_THREAD_AREA 25
311 if (ptrace (PTRACE_GET_THREAD_AREA
, pid
, addr
, &desc
) < 0)
314 *base_addr
= desc
[1];
319 void _initialize_x86_linux_nat ();
321 _initialize_x86_linux_nat ()
323 /* Initialize the debug register function vectors. */
324 x86_dr_low
.set_control
= x86_linux_dr_set_control
;
325 x86_dr_low
.set_addr
= x86_linux_dr_set_addr
;
326 x86_dr_low
.get_addr
= x86_linux_dr_get_addr
;
327 x86_dr_low
.get_status
= x86_linux_dr_get_status
;
328 x86_dr_low
.get_control
= x86_linux_dr_get_control
;
329 x86_set_debug_register_length (sizeof (void *));