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"
41 #include "nat/linux-nat.h"
43 /* Per-thread arch-specific data we want to keep. */
47 /* Non-zero if our copy differs from what's recorded in the thread. */
48 int debug_registers_changed;
51 /* Does the current host support PTRACE_GETREGSET? */
52 int have_ptrace_getregset = -1;
55 /* Return the offset of REGNUM in the u_debugreg field of struct
59 u_debugreg_offset (int regnum)
61 return (offsetof (struct user, u_debugreg)
62 + sizeof (((struct user *) 0)->u_debugreg[0]) * regnum);
65 /* Support for debug registers. */
67 /* Get debug register REGNUM value from only the one LWP of PTID. */
70 x86_linux_dr_get (ptid_t ptid, int regnum)
75 gdb_assert (ptid_lwp_p (ptid));
76 tid = ptid_get_lwp (ptid);
79 value = ptrace (PTRACE_PEEKUSER, tid, u_debugreg_offset (regnum), 0);
82 perror_with_name (_("Couldn't read debug register"));
87 /* Set debug register REGNUM to VALUE in only the one LWP of PTID. */
90 x86_linux_dr_set (ptid_t ptid, int regnum, unsigned long value)
94 gdb_assert (ptid_lwp_p (ptid));
95 tid = ptid_get_lwp (ptid);
98 ptrace (PTRACE_POKEUSER, tid, u_debugreg_offset (regnum), value);
100 perror_with_name (_("Couldn't write debug register"));
103 /* Return the inferior's debug register REGNUM. */
106 x86_linux_dr_get_addr (int regnum)
108 /* DR6 and DR7 are retrieved with some other way. */
109 gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);
111 return x86_linux_dr_get (current_lwp_ptid (), regnum);
114 /* Return the inferior's DR7 debug control register. */
117 x86_linux_dr_get_control (void)
119 return x86_linux_dr_get (current_lwp_ptid (), DR_CONTROL);
122 /* Get DR_STATUS from only the one LWP of INFERIOR_PTID. */
125 x86_linux_dr_get_status (void)
127 return x86_linux_dr_get (current_lwp_ptid (), DR_STATUS);
130 /* Callback for iterate_over_lwps. Update the debug registers of
134 update_debug_registers_callback (struct lwp_info *lwp, void *arg)
136 if (lwp->arch_private == NULL)
137 lwp->arch_private = XCNEW (struct arch_lwp_info);
139 /* The actual update is done later just before resuming the lwp, we
140 just mark that the registers need updating. */
141 lwp->arch_private->debug_registers_changed = 1;
143 /* If the lwp isn't stopped, force it to momentarily pause, so we
144 can update its debug registers. */
146 linux_stop_lwp (lwp);
148 /* Continue the iteration. */
152 /* Set DR_CONTROL to CONTROL in all LWPs of the current inferior. */
155 x86_linux_dr_set_control (unsigned long control)
157 ptid_t pid_ptid = pid_to_ptid (ptid_get_pid (current_lwp_ptid ()));
159 iterate_over_lwps (pid_ptid, update_debug_registers_callback, NULL);
162 /* Set address REGNUM (zero based) to ADDR in all LWPs of the current
166 x86_linux_dr_set_addr (int regnum, CORE_ADDR addr)
168 ptid_t pid_ptid = pid_to_ptid (ptid_get_pid (current_lwp_ptid ()));
170 gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);
172 iterate_over_lwps (pid_ptid, update_debug_registers_callback, NULL);
175 /* Called when resuming a thread.
176 If the debug regs have changed, update the thread's copies. */
179 x86_linux_prepare_to_resume (struct lwp_info *lwp)
181 int clear_status = 0;
183 /* NULL means this is the main thread still going through the shell,
184 or, no watchpoint has been set yet. In that case, there's
186 if (lwp->arch_private == NULL)
189 if (lwp->arch_private->debug_registers_changed)
191 struct x86_debug_reg_state *state
192 = x86_debug_reg_state (ptid_get_pid (lwp->ptid));
195 /* On Linux kernel before 2.6.33 commit
196 72f674d203cd230426437cdcf7dd6f681dad8b0d
197 if you enable a breakpoint by the DR_CONTROL bits you need to have
198 already written the corresponding DR_FIRSTADDR...DR_LASTADDR registers.
200 Ensure DR_CONTROL gets written as the very last register here. */
202 /* Clear DR_CONTROL first. In some cases, setting DR0-3 to a
203 value that doesn't match what is enabled in DR_CONTROL
204 results in EINVAL. */
205 x86_linux_dr_set (lwp->ptid, DR_CONTROL, 0);
207 ALL_DEBUG_ADDRESS_REGISTERS (i)
208 if (state->dr_ref_count[i] > 0)
210 x86_linux_dr_set (lwp->ptid, i, state->dr_mirror[i]);
212 /* If we're setting a watchpoint, any change the inferior
213 had done itself to the debug registers needs to be
214 discarded, otherwise, x86_stopped_data_address can get
219 /* If DR_CONTROL is supposed to be zero, we've already set it
221 if (state->dr_control_mirror != 0)
222 x86_linux_dr_set (lwp->ptid, DR_CONTROL, state->dr_control_mirror);
224 lwp->arch_private->debug_registers_changed = 0;
227 if (clear_status || lwp->stop_reason == TARGET_STOPPED_BY_WATCHPOINT)
228 x86_linux_dr_set (lwp->ptid, DR_STATUS, 0);
232 x86_linux_new_thread (struct lwp_info *lp)
234 struct arch_lwp_info *info = XCNEW (struct arch_lwp_info);
236 info->debug_registers_changed = 1;
238 lp->arch_private = info;
242 /* linux_nat_new_fork hook. */
245 x86_linux_new_fork (struct lwp_info *parent, pid_t child_pid)
248 struct x86_debug_reg_state *parent_state;
249 struct x86_debug_reg_state *child_state;
251 /* NULL means no watchpoint has ever been set in the parent. In
252 that case, there's nothing to do. */
253 if (parent->arch_private == NULL)
256 /* Linux kernel before 2.6.33 commit
257 72f674d203cd230426437cdcf7dd6f681dad8b0d
258 will inherit hardware debug registers from parent
259 on fork/vfork/clone. Newer Linux kernels create such tasks with
260 zeroed debug registers.
262 GDB core assumes the child inherits the watchpoints/hw
263 breakpoints of the parent, and will remove them all from the
264 forked off process. Copy the debug registers mirrors into the
265 new process so that all breakpoints and watchpoints can be
266 removed together. The debug registers mirror will become zeroed
267 in the end before detaching the forked off process, thus making
268 this compatible with older Linux kernels too. */
270 parent_pid = ptid_get_pid (parent->ptid);
271 parent_state = x86_debug_reg_state (parent_pid);
272 child_state = x86_debug_reg_state (child_pid);
273 *child_state = *parent_state;
277 static void (*super_post_startup_inferior) (struct target_ops *self,
281 x86_linux_child_post_startup_inferior (struct target_ops *self, ptid_t ptid)
283 x86_cleanup_dregs ();
284 super_post_startup_inferior (self, ptid);
288 /* Value of CS segment register:
290 32bit process: 0x23 */
291 #define AMD64_LINUX_USER64_CS 0x33
293 /* Value of DS segment register:
296 #define AMD64_LINUX_X32_DS 0x2b
299 /* Get Linux/x86 target description from running target. */
301 static const struct target_desc *
302 x86_linux_read_description (struct target_ops *ops)
309 static uint64_t xcr0;
310 uint64_t xcr0_features_bits;
312 /* GNU/Linux LWP ID's are process ID's. */
313 tid = ptid_get_lwp (inferior_ptid);
315 tid = ptid_get_pid (inferior_ptid); /* Not a threaded program. */
322 /* Get CS register. */
324 cs = ptrace (PTRACE_PEEKUSER, tid,
325 offsetof (struct user_regs_struct, cs), 0);
327 perror_with_name (_("Couldn't get CS register"));
329 is_64bit = cs == AMD64_LINUX_USER64_CS;
331 /* Get DS register. */
333 ds = ptrace (PTRACE_PEEKUSER, tid,
334 offsetof (struct user_regs_struct, ds), 0);
336 perror_with_name (_("Couldn't get DS register"));
338 is_x32 = ds == AMD64_LINUX_X32_DS;
340 if (sizeof (void *) == 4 && is_64bit && !is_x32)
341 error (_("Can't debug 64-bit process with 32-bit GDB"));
343 #elif HAVE_PTRACE_GETFPXREGS
344 if (have_ptrace_getfpxregs == -1)
346 elf_fpxregset_t fpxregs;
348 if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
350 have_ptrace_getfpxregs = 0;
351 have_ptrace_getregset = 0;
352 return tdesc_i386_mmx_linux;
357 if (have_ptrace_getregset == -1)
359 uint64_t xstateregs[(X86_XSTATE_SSE_SIZE / sizeof (uint64_t))];
362 iov.iov_base = xstateregs;
363 iov.iov_len = sizeof (xstateregs);
365 /* Check if PTRACE_GETREGSET works. */
366 if (ptrace (PTRACE_GETREGSET, tid,
367 (unsigned int) NT_X86_XSTATE, &iov) < 0)
368 have_ptrace_getregset = 0;
371 have_ptrace_getregset = 1;
373 /* Get XCR0 from XSAVE extended state. */
374 xcr0 = xstateregs[(I386_LINUX_XSAVE_XCR0_OFFSET
375 / sizeof (uint64_t))];
379 /* Check the native XCR0 only if PTRACE_GETREGSET is available. If
380 PTRACE_GETREGSET is not available then set xcr0_features_bits to
381 zero so that the "no-features" descriptions are returned by the
383 if (have_ptrace_getregset)
384 xcr0_features_bits = xcr0 & X86_XSTATE_ALL_MASK;
386 xcr0_features_bits = 0;
391 switch (xcr0_features_bits)
393 case X86_XSTATE_MPX_AVX512_MASK:
394 case X86_XSTATE_AVX512_MASK:
396 return tdesc_x32_avx512_linux;
398 return tdesc_amd64_avx512_linux;
399 case X86_XSTATE_MPX_MASK:
401 return tdesc_x32_avx_linux; /* No MPX on x32 using AVX. */
403 return tdesc_amd64_mpx_linux;
404 case X86_XSTATE_AVX_MASK:
406 return tdesc_x32_avx_linux;
408 return tdesc_amd64_avx_linux;
411 return tdesc_x32_linux;
413 return tdesc_amd64_linux;
419 switch (xcr0_features_bits)
421 case X86_XSTATE_MPX_AVX512_MASK:
422 case X86_XSTATE_AVX512_MASK:
423 return tdesc_i386_avx512_linux;
424 case X86_XSTATE_MPX_MASK:
425 return tdesc_i386_mpx_linux;
426 case X86_XSTATE_AVX_MASK:
427 return tdesc_i386_avx_linux;
429 return tdesc_i386_linux;
433 gdb_assert_not_reached ("failed to return tdesc");
437 /* Enable branch tracing. */
439 static struct btrace_target_info *
440 x86_linux_enable_btrace (struct target_ops *self, ptid_t ptid,
441 const struct btrace_config *conf)
443 struct btrace_target_info *tinfo;
444 struct gdbarch *gdbarch;
447 tinfo = linux_enable_btrace (ptid, conf);
450 error (_("Could not enable branch tracing for %s: %s."),
451 target_pid_to_str (ptid), safe_strerror (errno));
453 /* Fill in the size of a pointer in bits. */
454 if (tinfo->ptr_bits == 0)
456 gdbarch = target_thread_architecture (ptid);
457 tinfo->ptr_bits = gdbarch_ptr_bit (gdbarch);
462 /* Disable branch tracing. */
465 x86_linux_disable_btrace (struct target_ops *self,
466 struct btrace_target_info *tinfo)
468 enum btrace_error errcode = linux_disable_btrace (tinfo);
470 if (errcode != BTRACE_ERR_NONE)
471 error (_("Could not disable branch tracing."));
474 /* Teardown branch tracing. */
477 x86_linux_teardown_btrace (struct target_ops *self,
478 struct btrace_target_info *tinfo)
481 linux_disable_btrace (tinfo);
484 static enum btrace_error
485 x86_linux_read_btrace (struct target_ops *self,
486 struct btrace_data *data,
487 struct btrace_target_info *btinfo,
488 enum btrace_read_type type)
490 return linux_read_btrace (data, btinfo, type);
493 /* See to_btrace_conf in target.h. */
495 static const struct btrace_config *
496 x86_linux_btrace_conf (struct target_ops *self,
497 const struct btrace_target_info *btinfo)
499 return linux_btrace_conf (btinfo);
504 /* Helper for ps_get_thread_area. Sets BASE_ADDR to a pointer to
505 the thread local storage (or its descriptor) and returns PS_OK
506 on success. Returns PS_ERR on failure. */
509 x86_linux_get_thread_area (pid_t pid, void *addr, unsigned int *base_addr)
511 /* NOTE: cagney/2003-08-26: The definition of this buffer is found
512 in the kernel header <asm-i386/ldt.h>. It, after padding, is 4 x
513 4 byte integers in size: `entry_number', `base_addr', `limit',
514 and a bunch of status bits.
516 The values returned by this ptrace call should be part of the
517 regcache buffer, and ps_get_thread_area should channel its
518 request through the regcache. That way remote targets could
519 provide the value using the remote protocol and not this direct
522 Is this function needed? I'm guessing that the `base' is the
523 address of a descriptor that libthread_db uses to find the
524 thread local address base that GDB needs. Perhaps that
525 descriptor is defined by the ABI. Anyway, given that
526 libthread_db calls this function without prompting (gdb
527 requesting tls base) I guess it needs info in there anyway. */
528 unsigned int desc[4];
530 /* This code assumes that "int" is 32 bits and that
531 GET_THREAD_AREA returns no more than 4 int values. */
532 gdb_assert (sizeof (int) == 4);
534 #ifndef PTRACE_GET_THREAD_AREA
535 #define PTRACE_GET_THREAD_AREA 25
538 if (ptrace (PTRACE_GET_THREAD_AREA, pid, addr, &desc) < 0)
541 *base_addr = desc[1];
546 /* Create an x86 GNU/Linux target. */
549 x86_linux_create_target (void)
551 /* Fill in the generic GNU/Linux methods. */
552 struct target_ops *t = linux_target ();
554 /* Initialize the debug register function vectors. */
555 x86_use_watchpoints (t);
556 x86_dr_low.set_control = x86_linux_dr_set_control;
557 x86_dr_low.set_addr = x86_linux_dr_set_addr;
558 x86_dr_low.get_addr = x86_linux_dr_get_addr;
559 x86_dr_low.get_status = x86_linux_dr_get_status;
560 x86_dr_low.get_control = x86_linux_dr_get_control;
561 x86_set_debug_register_length (sizeof (void *));
563 /* Override the GNU/Linux inferior startup hook. */
564 super_post_startup_inferior = t->to_post_startup_inferior;
565 t->to_post_startup_inferior = x86_linux_child_post_startup_inferior;
567 /* Add the description reader. */
568 t->to_read_description = x86_linux_read_description;
570 /* Add btrace methods. */
571 t->to_supports_btrace = linux_supports_btrace;
572 t->to_enable_btrace = x86_linux_enable_btrace;
573 t->to_disable_btrace = x86_linux_disable_btrace;
574 t->to_teardown_btrace = x86_linux_teardown_btrace;
575 t->to_read_btrace = x86_linux_read_btrace;
576 t->to_btrace_conf = x86_linux_btrace_conf;
581 /* Add an x86 GNU/Linux target. */
584 x86_linux_add_target (struct target_ops *t)
586 linux_nat_add_target (t);
587 linux_nat_set_new_thread (t, x86_linux_new_thread);
588 linux_nat_set_new_fork (t, x86_linux_new_fork);
589 linux_nat_set_forget_process (t, x86_forget_process);
590 linux_nat_set_prepare_to_resume (t, x86_linux_prepare_to_resume);