1 /* Native-dependent code for GNU/Linux x86 (i386 and x86-64).
3 Copyright (C) 1999-2015 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 <sys/ptrace.h>
26 #include <sys/procfs.h>
30 #include "linux-nat.h"
32 #include "i386-linux-nat.h"
34 #include "x86-linux-nat.h"
35 #include "i386-linux-tdep.h"
37 #include "amd64-linux-tdep.h"
39 #include "x86-xstate.h"
40 #include "nat/linux-btrace.h"
42 /* Per-thread arch-specific data we want to keep. */
46 /* Non-zero if our copy differs from what's recorded in the thread. */
47 int debug_registers_changed
;
50 /* Does the current host support PTRACE_GETREGSET? */
51 int have_ptrace_getregset
= -1;
54 /* Return the offset of REGNUM in the u_debugreg field of struct
58 u_debugreg_offset (int regnum
)
60 return (offsetof (struct user
, u_debugreg
)
61 + sizeof (((struct user
*) 0)->u_debugreg
[0]) * regnum
);
64 /* Support for debug registers. */
66 /* Get debug register REGNUM value from only the one LWP of PTID. */
69 x86_linux_dr_get (ptid_t ptid
, int regnum
)
74 gdb_assert (ptid_lwp_p (ptid
));
75 tid
= ptid_get_lwp (ptid
);
78 value
= ptrace (PTRACE_PEEKUSER
, tid
, u_debugreg_offset (regnum
), 0);
81 perror_with_name (_("Couldn't read debug register"));
86 /* Set debug register REGNUM to VALUE in only the one LWP of PTID. */
89 x86_linux_dr_set (ptid_t ptid
, int regnum
, unsigned long value
)
93 gdb_assert (ptid_lwp_p (ptid
));
94 tid
= ptid_get_lwp (ptid
);
97 ptrace (PTRACE_POKEUSER
, tid
, u_debugreg_offset (regnum
), value
);
99 perror_with_name (_("Couldn't write debug register"));
102 /* Return the inferior's debug register REGNUM. */
105 x86_linux_dr_get_addr (int regnum
)
107 /* DR6 and DR7 are retrieved with some other way. */
108 gdb_assert (DR_FIRSTADDR
<= regnum
&& regnum
<= DR_LASTADDR
);
110 return x86_linux_dr_get (inferior_ptid
, regnum
);
113 /* Return the inferior's DR7 debug control register. */
116 x86_linux_dr_get_control (void)
118 return x86_linux_dr_get (inferior_ptid
, DR_CONTROL
);
121 /* Get DR_STATUS from only the one LWP of INFERIOR_PTID. */
124 x86_linux_dr_get_status (void)
126 return x86_linux_dr_get (inferior_ptid
, DR_STATUS
);
129 /* Callback for iterate_over_lwps. Update the debug registers of
133 update_debug_registers_callback (struct lwp_info
*lwp
, void *arg
)
135 if (lwp
->arch_private
== NULL
)
136 lwp
->arch_private
= XCNEW (struct arch_lwp_info
);
138 /* The actual update is done later just before resuming the lwp, we
139 just mark that the registers need updating. */
140 lwp
->arch_private
->debug_registers_changed
= 1;
142 /* If the lwp isn't stopped, force it to momentarily pause, so we
143 can update its debug registers. */
145 linux_stop_lwp (lwp
);
147 /* Continue the iteration. */
151 /* Set DR_CONTROL to CONTROL in all LWPs of the current inferior. */
154 x86_linux_dr_set_control (unsigned long control
)
156 ptid_t pid_ptid
= pid_to_ptid (ptid_get_pid (inferior_ptid
));
158 iterate_over_lwps (pid_ptid
, update_debug_registers_callback
, NULL
);
161 /* Set address REGNUM (zero based) to ADDR in all LWPs of the current
165 x86_linux_dr_set_addr (int regnum
, CORE_ADDR addr
)
167 ptid_t pid_ptid
= pid_to_ptid (ptid_get_pid (inferior_ptid
));
169 gdb_assert (regnum
>= 0 && regnum
<= DR_LASTADDR
- DR_FIRSTADDR
);
171 iterate_over_lwps (pid_ptid
, update_debug_registers_callback
, NULL
);
174 /* Called when resuming a thread.
175 If the debug regs have changed, update the thread's copies. */
178 x86_linux_prepare_to_resume (struct lwp_info
*lwp
)
180 int clear_status
= 0;
182 /* NULL means this is the main thread still going through the shell,
183 or, no watchpoint has been set yet. In that case, there's
185 if (lwp
->arch_private
== NULL
)
188 if (lwp
->arch_private
->debug_registers_changed
)
190 struct x86_debug_reg_state
*state
191 = x86_debug_reg_state (ptid_get_pid (lwp
->ptid
));
194 /* On Linux kernel before 2.6.33 commit
195 72f674d203cd230426437cdcf7dd6f681dad8b0d
196 if you enable a breakpoint by the DR_CONTROL bits you need to have
197 already written the corresponding DR_FIRSTADDR...DR_LASTADDR registers.
199 Ensure DR_CONTROL gets written as the very last register here. */
201 /* Clear DR_CONTROL first. In some cases, setting DR0-3 to a
202 value that doesn't match what is enabled in DR_CONTROL
203 results in EINVAL. */
204 x86_linux_dr_set (lwp
->ptid
, DR_CONTROL
, 0);
206 ALL_DEBUG_ADDRESS_REGISTERS (i
)
207 if (state
->dr_ref_count
[i
] > 0)
209 x86_linux_dr_set (lwp
->ptid
, i
, state
->dr_mirror
[i
]);
211 /* If we're setting a watchpoint, any change the inferior
212 had done itself to the debug registers needs to be
213 discarded, otherwise, x86_stopped_data_address can get
218 /* If DR_CONTROL is supposed to be zero, we've already set it
220 if (state
->dr_control_mirror
!= 0)
221 x86_linux_dr_set (lwp
->ptid
, DR_CONTROL
, state
->dr_control_mirror
);
223 lwp
->arch_private
->debug_registers_changed
= 0;
226 if (clear_status
|| lwp
->stop_reason
== LWP_STOPPED_BY_WATCHPOINT
)
227 x86_linux_dr_set (lwp
->ptid
, DR_STATUS
, 0);
231 x86_linux_new_thread (struct lwp_info
*lp
)
233 struct arch_lwp_info
*info
= XCNEW (struct arch_lwp_info
);
235 info
->debug_registers_changed
= 1;
237 lp
->arch_private
= info
;
241 /* linux_nat_new_fork hook. */
244 x86_linux_new_fork (struct lwp_info
*parent
, pid_t child_pid
)
247 struct x86_debug_reg_state
*parent_state
;
248 struct x86_debug_reg_state
*child_state
;
250 /* NULL means no watchpoint has ever been set in the parent. In
251 that case, there's nothing to do. */
252 if (parent
->arch_private
== NULL
)
255 /* Linux kernel before 2.6.33 commit
256 72f674d203cd230426437cdcf7dd6f681dad8b0d
257 will inherit hardware debug registers from parent
258 on fork/vfork/clone. Newer Linux kernels create such tasks with
259 zeroed debug registers.
261 GDB core assumes the child inherits the watchpoints/hw
262 breakpoints of the parent, and will remove them all from the
263 forked off process. Copy the debug registers mirrors into the
264 new process so that all breakpoints and watchpoints can be
265 removed together. The debug registers mirror will become zeroed
266 in the end before detaching the forked off process, thus making
267 this compatible with older Linux kernels too. */
269 parent_pid
= ptid_get_pid (parent
->ptid
);
270 parent_state
= x86_debug_reg_state (parent_pid
);
271 child_state
= x86_debug_reg_state (child_pid
);
272 *child_state
= *parent_state
;
276 static void (*super_post_startup_inferior
) (struct target_ops
*self
,
280 x86_linux_child_post_startup_inferior (struct target_ops
*self
, ptid_t ptid
)
282 x86_cleanup_dregs ();
283 super_post_startup_inferior (self
, ptid
);
287 /* Value of CS segment register:
289 32bit process: 0x23 */
290 #define AMD64_LINUX_USER64_CS 0x33
292 /* Value of DS segment register:
295 #define AMD64_LINUX_X32_DS 0x2b
298 /* Get Linux/x86 target description from running target. */
300 static const struct target_desc
*
301 x86_linux_read_description (struct target_ops
*ops
)
308 static uint64_t xcr0
;
309 uint64_t xcr0_features_bits
;
311 /* GNU/Linux LWP ID's are process ID's. */
312 tid
= ptid_get_lwp (inferior_ptid
);
314 tid
= ptid_get_pid (inferior_ptid
); /* Not a threaded program. */
321 /* Get CS register. */
323 cs
= ptrace (PTRACE_PEEKUSER
, tid
,
324 offsetof (struct user_regs_struct
, cs
), 0);
326 perror_with_name (_("Couldn't get CS register"));
328 is_64bit
= cs
== AMD64_LINUX_USER64_CS
;
330 /* Get DS register. */
332 ds
= ptrace (PTRACE_PEEKUSER
, tid
,
333 offsetof (struct user_regs_struct
, ds
), 0);
335 perror_with_name (_("Couldn't get DS register"));
337 is_x32
= ds
== AMD64_LINUX_X32_DS
;
339 if (sizeof (void *) == 4 && is_64bit
&& !is_x32
)
340 error (_("Can't debug 64-bit process with 32-bit GDB"));
342 #elif HAVE_PTRACE_GETFPXREGS
343 if (have_ptrace_getfpxregs
== -1)
345 elf_fpxregset_t fpxregs
;
347 if (ptrace (PTRACE_GETFPXREGS
, tid
, 0, (int) &fpxregs
) < 0)
349 have_ptrace_getfpxregs
= 0;
350 have_ptrace_getregset
= 0;
351 return tdesc_i386_mmx_linux
;
356 if (have_ptrace_getregset
== -1)
358 uint64_t xstateregs
[(X86_XSTATE_SSE_SIZE
/ sizeof (uint64_t))];
361 iov
.iov_base
= xstateregs
;
362 iov
.iov_len
= sizeof (xstateregs
);
364 /* Check if PTRACE_GETREGSET works. */
365 if (ptrace (PTRACE_GETREGSET
, tid
,
366 (unsigned int) NT_X86_XSTATE
, &iov
) < 0)
367 have_ptrace_getregset
= 0;
370 have_ptrace_getregset
= 1;
372 /* Get XCR0 from XSAVE extended state. */
373 xcr0
= xstateregs
[(I386_LINUX_XSAVE_XCR0_OFFSET
374 / sizeof (uint64_t))];
378 /* Check the native XCR0 only if PTRACE_GETREGSET is available. If
379 PTRACE_GETREGSET is not available then set xcr0_features_bits to
380 zero so that the "no-features" descriptions are returned by the
382 if (have_ptrace_getregset
)
383 xcr0_features_bits
= xcr0
& X86_XSTATE_ALL_MASK
;
385 xcr0_features_bits
= 0;
390 switch (xcr0_features_bits
)
392 case X86_XSTATE_MPX_AVX512_MASK
:
393 case X86_XSTATE_AVX512_MASK
:
395 return tdesc_x32_avx512_linux
;
397 return tdesc_amd64_avx512_linux
;
398 case X86_XSTATE_MPX_MASK
:
400 return tdesc_x32_avx_linux
; /* No MPX on x32 using AVX. */
402 return tdesc_amd64_mpx_linux
;
403 case X86_XSTATE_AVX_MASK
:
405 return tdesc_x32_avx_linux
;
407 return tdesc_amd64_avx_linux
;
410 return tdesc_x32_linux
;
412 return tdesc_amd64_linux
;
418 switch (xcr0_features_bits
)
420 case X86_XSTATE_MPX_AVX512_MASK
:
421 case X86_XSTATE_AVX512_MASK
:
422 return tdesc_i386_avx512_linux
;
423 case X86_XSTATE_MPX_MASK
:
424 return tdesc_i386_mpx_linux
;
425 case X86_XSTATE_AVX_MASK
:
426 return tdesc_i386_avx_linux
;
428 return tdesc_i386_linux
;
432 gdb_assert_not_reached ("failed to return tdesc");
436 /* Enable branch tracing. */
438 static struct btrace_target_info
*
439 x86_linux_enable_btrace (struct target_ops
*self
, ptid_t ptid
,
440 const struct btrace_config
*conf
)
442 struct btrace_target_info
*tinfo
;
443 struct gdbarch
*gdbarch
;
446 tinfo
= linux_enable_btrace (ptid
, conf
);
449 error (_("Could not enable branch tracing for %s: %s."),
450 target_pid_to_str (ptid
), safe_strerror (errno
));
452 /* Fill in the size of a pointer in bits. */
453 gdbarch
= target_thread_architecture (ptid
);
454 tinfo
->ptr_bits
= gdbarch_ptr_bit (gdbarch
);
459 /* Disable branch tracing. */
462 x86_linux_disable_btrace (struct target_ops
*self
,
463 struct btrace_target_info
*tinfo
)
465 enum btrace_error errcode
= linux_disable_btrace (tinfo
);
467 if (errcode
!= BTRACE_ERR_NONE
)
468 error (_("Could not disable branch tracing."));
471 /* Teardown branch tracing. */
474 x86_linux_teardown_btrace (struct target_ops
*self
,
475 struct btrace_target_info
*tinfo
)
478 linux_disable_btrace (tinfo
);
481 static enum btrace_error
482 x86_linux_read_btrace (struct target_ops
*self
,
483 struct btrace_data
*data
,
484 struct btrace_target_info
*btinfo
,
485 enum btrace_read_type type
)
487 return linux_read_btrace (data
, btinfo
, type
);
490 /* See to_btrace_conf in target.h. */
492 static const struct btrace_config
*
493 x86_linux_btrace_conf (struct target_ops
*self
,
494 const struct btrace_target_info
*btinfo
)
496 return linux_btrace_conf (btinfo
);
501 /* Helper for ps_get_thread_area. Sets BASE_ADDR to a pointer to
502 the thread local storage (or its descriptor) and returns PS_OK
503 on success. Returns PS_ERR on failure. */
506 x86_linux_get_thread_area (pid_t pid
, void *addr
, unsigned int *base_addr
)
508 /* NOTE: cagney/2003-08-26: The definition of this buffer is found
509 in the kernel header <asm-i386/ldt.h>. It, after padding, is 4 x
510 4 byte integers in size: `entry_number', `base_addr', `limit',
511 and a bunch of status bits.
513 The values returned by this ptrace call should be part of the
514 regcache buffer, and ps_get_thread_area should channel its
515 request through the regcache. That way remote targets could
516 provide the value using the remote protocol and not this direct
519 Is this function needed? I'm guessing that the `base' is the
520 address of a descriptor that libthread_db uses to find the
521 thread local address base that GDB needs. Perhaps that
522 descriptor is defined by the ABI. Anyway, given that
523 libthread_db calls this function without prompting (gdb
524 requesting tls base) I guess it needs info in there anyway. */
525 unsigned int desc
[4];
527 /* This code assumes that "int" is 32 bits and that
528 GET_THREAD_AREA returns no more than 4 int values. */
529 gdb_assert (sizeof (int) == 4);
531 #ifndef PTRACE_GET_THREAD_AREA
532 #define PTRACE_GET_THREAD_AREA 25
535 if (ptrace (PTRACE_GET_THREAD_AREA
, pid
, addr
, &desc
) < 0)
538 *base_addr
= desc
[1];
543 /* Create an x86 GNU/Linux target. */
546 x86_linux_create_target (void)
548 /* Fill in the generic GNU/Linux methods. */
549 struct target_ops
*t
= linux_target ();
551 /* Initialize the debug register function vectors. */
552 x86_use_watchpoints (t
);
553 x86_dr_low
.set_control
= x86_linux_dr_set_control
;
554 x86_dr_low
.set_addr
= x86_linux_dr_set_addr
;
555 x86_dr_low
.get_addr
= x86_linux_dr_get_addr
;
556 x86_dr_low
.get_status
= x86_linux_dr_get_status
;
557 x86_dr_low
.get_control
= x86_linux_dr_get_control
;
558 x86_set_debug_register_length (sizeof (void *));
560 /* Override the GNU/Linux inferior startup hook. */
561 super_post_startup_inferior
= t
->to_post_startup_inferior
;
562 t
->to_post_startup_inferior
= x86_linux_child_post_startup_inferior
;
564 /* Add the description reader. */
565 t
->to_read_description
= x86_linux_read_description
;
567 /* Add btrace methods. */
568 t
->to_supports_btrace
= linux_supports_btrace
;
569 t
->to_enable_btrace
= x86_linux_enable_btrace
;
570 t
->to_disable_btrace
= x86_linux_disable_btrace
;
571 t
->to_teardown_btrace
= x86_linux_teardown_btrace
;
572 t
->to_read_btrace
= x86_linux_read_btrace
;
573 t
->to_btrace_conf
= x86_linux_btrace_conf
;
578 /* Add an x86 GNU/Linux target. */
581 x86_linux_add_target (struct target_ops
*t
)
583 linux_nat_add_target (t
);
584 linux_nat_set_new_thread (t
, x86_linux_new_thread
);
585 linux_nat_set_new_fork (t
, x86_linux_new_fork
);
586 linux_nat_set_forget_process (t
, x86_forget_process
);
587 linux_nat_set_prepare_to_resume (t
, x86_linux_prepare_to_resume
);