xref: /netbsd-src/external/gpl3/gdb.old/dist/gdb/mips-linux-nat.c (revision d90047b5d07facf36e6c01dcc0bded8997ce9cc2)
1 /* Native-dependent code for GNU/Linux on MIPS processors.
2 
3    Copyright (C) 2001-2017 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 "defs.h"
21 #include "command.h"
22 #include "gdbcmd.h"
23 #include "inferior.h"
24 #include "mips-tdep.h"
25 #include "target.h"
26 #include "regcache.h"
27 #include "linux-nat.h"
28 #include "mips-linux-tdep.h"
29 #include "target-descriptions.h"
30 
31 #include "gdb_proc_service.h"
32 #include "gregset.h"
33 
34 #include <sgidefs.h>
35 #include "nat/gdb_ptrace.h"
36 #include <asm/ptrace.h>
37 #include "inf-ptrace.h"
38 
39 #include "nat/mips-linux-watch.h"
40 
41 #include "features/mips-linux.c"
42 #include "features/mips-dsp-linux.c"
43 #include "features/mips64-linux.c"
44 #include "features/mips64-dsp-linux.c"
45 
46 #ifndef PTRACE_GET_THREAD_AREA
47 #define PTRACE_GET_THREAD_AREA 25
48 #endif
49 
50 /* Assume that we have PTRACE_GETREGS et al. support.  If we do not,
51    we'll clear this and use PTRACE_PEEKUSER instead.  */
52 static int have_ptrace_regsets = 1;
53 
54 /* Saved function pointers to fetch and store a single register using
55    PTRACE_PEEKUSER and PTRACE_POKEUSER.  */
56 
57 static void (*super_fetch_registers) (struct target_ops *,
58 				      struct regcache *, int);
59 static void (*super_store_registers) (struct target_ops *,
60 				      struct regcache *, int);
61 
62 static void (*super_close) (struct target_ops *);
63 
64 /* Map gdb internal register number to ptrace ``address''.
65    These ``addresses'' are normally defined in <asm/ptrace.h>.
66 
67    ptrace does not provide a way to read (or set) MIPS_PS_REGNUM,
68    and there's no point in reading or setting MIPS_ZERO_REGNUM.
69    We also can not set BADVADDR, CAUSE, or FCRIR via ptrace().  */
70 
71 static CORE_ADDR
72 mips_linux_register_addr (struct gdbarch *gdbarch, int regno, int store)
73 {
74   CORE_ADDR regaddr;
75 
76   if (regno < 0 || regno >= gdbarch_num_regs (gdbarch))
77     error (_("Bogon register number %d."), regno);
78 
79   if (regno > MIPS_ZERO_REGNUM && regno < MIPS_ZERO_REGNUM + 32)
80     regaddr = regno;
81   else if ((regno >= mips_regnum (gdbarch)->fp0)
82 	   && (regno < mips_regnum (gdbarch)->fp0 + 32))
83     regaddr = FPR_BASE + (regno - mips_regnum (gdbarch)->fp0);
84   else if (regno == mips_regnum (gdbarch)->pc)
85     regaddr = PC;
86   else if (regno == mips_regnum (gdbarch)->cause)
87     regaddr = store? (CORE_ADDR) -1 : CAUSE;
88   else if (regno == mips_regnum (gdbarch)->badvaddr)
89     regaddr = store? (CORE_ADDR) -1 : BADVADDR;
90   else if (regno == mips_regnum (gdbarch)->lo)
91     regaddr = MMLO;
92   else if (regno == mips_regnum (gdbarch)->hi)
93     regaddr = MMHI;
94   else if (regno == mips_regnum (gdbarch)->fp_control_status)
95     regaddr = FPC_CSR;
96   else if (regno == mips_regnum (gdbarch)->fp_implementation_revision)
97     regaddr = store? (CORE_ADDR) -1 : FPC_EIR;
98   else if (mips_regnum (gdbarch)->dspacc != -1
99 	   && regno >= mips_regnum (gdbarch)->dspacc
100 	   && regno < mips_regnum (gdbarch)->dspacc + 6)
101     regaddr = DSP_BASE + (regno - mips_regnum (gdbarch)->dspacc);
102   else if (regno == mips_regnum (gdbarch)->dspctl)
103     regaddr = DSP_CONTROL;
104   else if (mips_linux_restart_reg_p (gdbarch) && regno == MIPS_RESTART_REGNUM)
105     regaddr = 0;
106   else
107     regaddr = (CORE_ADDR) -1;
108 
109   return regaddr;
110 }
111 
112 static CORE_ADDR
113 mips64_linux_register_addr (struct gdbarch *gdbarch, int regno, int store)
114 {
115   CORE_ADDR regaddr;
116 
117   if (regno < 0 || regno >= gdbarch_num_regs (gdbarch))
118     error (_("Bogon register number %d."), regno);
119 
120   if (regno > MIPS_ZERO_REGNUM && regno < MIPS_ZERO_REGNUM + 32)
121     regaddr = regno;
122   else if ((regno >= mips_regnum (gdbarch)->fp0)
123 	   && (regno < mips_regnum (gdbarch)->fp0 + 32))
124     regaddr = MIPS64_FPR_BASE + (regno - gdbarch_fp0_regnum (gdbarch));
125   else if (regno == mips_regnum (gdbarch)->pc)
126     regaddr = MIPS64_PC;
127   else if (regno == mips_regnum (gdbarch)->cause)
128     regaddr = store? (CORE_ADDR) -1 : MIPS64_CAUSE;
129   else if (regno == mips_regnum (gdbarch)->badvaddr)
130     regaddr = store? (CORE_ADDR) -1 : MIPS64_BADVADDR;
131   else if (regno == mips_regnum (gdbarch)->lo)
132     regaddr = MIPS64_MMLO;
133   else if (regno == mips_regnum (gdbarch)->hi)
134     regaddr = MIPS64_MMHI;
135   else if (regno == mips_regnum (gdbarch)->fp_control_status)
136     regaddr = MIPS64_FPC_CSR;
137   else if (regno == mips_regnum (gdbarch)->fp_implementation_revision)
138     regaddr = store? (CORE_ADDR) -1 : MIPS64_FPC_EIR;
139   else if (mips_regnum (gdbarch)->dspacc != -1
140 	   && regno >= mips_regnum (gdbarch)->dspacc
141 	   && regno < mips_regnum (gdbarch)->dspacc + 6)
142     regaddr = DSP_BASE + (regno - mips_regnum (gdbarch)->dspacc);
143   else if (regno == mips_regnum (gdbarch)->dspctl)
144     regaddr = DSP_CONTROL;
145   else if (mips_linux_restart_reg_p (gdbarch) && regno == MIPS_RESTART_REGNUM)
146     regaddr = 0;
147   else
148     regaddr = (CORE_ADDR) -1;
149 
150   return regaddr;
151 }
152 
153 /* Fetch the thread-local storage pointer for libthread_db.  */
154 
155 ps_err_e
156 ps_get_thread_area (struct ps_prochandle *ph,
157                     lwpid_t lwpid, int idx, void **base)
158 {
159   if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) != 0)
160     return PS_ERR;
161 
162   /* IDX is the bias from the thread pointer to the beginning of the
163      thread descriptor.  It has to be subtracted due to implementation
164      quirks in libthread_db.  */
165   *base = (void *) ((char *)*base - idx);
166 
167   return PS_OK;
168 }
169 
170 /* Wrapper functions.  These are only used by libthread_db.  */
171 
172 void
173 supply_gregset (struct regcache *regcache, const gdb_gregset_t *gregsetp)
174 {
175   if (mips_isa_regsize (get_regcache_arch (regcache)) == 4)
176     mips_supply_gregset (regcache, (const mips_elf_gregset_t *) gregsetp);
177   else
178     mips64_supply_gregset (regcache, (const mips64_elf_gregset_t *) gregsetp);
179 }
180 
181 void
182 fill_gregset (const struct regcache *regcache,
183 	      gdb_gregset_t *gregsetp, int regno)
184 {
185   if (mips_isa_regsize (get_regcache_arch (regcache)) == 4)
186     mips_fill_gregset (regcache, (mips_elf_gregset_t *) gregsetp, regno);
187   else
188     mips64_fill_gregset (regcache, (mips64_elf_gregset_t *) gregsetp, regno);
189 }
190 
191 void
192 supply_fpregset (struct regcache *regcache, const gdb_fpregset_t *fpregsetp)
193 {
194   if (mips_isa_regsize (get_regcache_arch (regcache)) == 4)
195     mips_supply_fpregset (regcache, (const mips_elf_fpregset_t *) fpregsetp);
196   else
197     mips64_supply_fpregset (regcache,
198 			    (const mips64_elf_fpregset_t *) fpregsetp);
199 }
200 
201 void
202 fill_fpregset (const struct regcache *regcache,
203 	       gdb_fpregset_t *fpregsetp, int regno)
204 {
205   if (mips_isa_regsize (get_regcache_arch (regcache)) == 4)
206     mips_fill_fpregset (regcache, (mips_elf_fpregset_t *) fpregsetp, regno);
207   else
208     mips64_fill_fpregset (regcache,
209 			  (mips64_elf_fpregset_t *) fpregsetp, regno);
210 }
211 
212 
213 /* Fetch REGNO (or all registers if REGNO == -1) from the target
214    using PTRACE_GETREGS et al.  */
215 
216 static void
217 mips64_linux_regsets_fetch_registers (struct target_ops *ops,
218 				      struct regcache *regcache, int regno)
219 {
220   struct gdbarch *gdbarch = get_regcache_arch (regcache);
221   int is_fp, is_dsp;
222   int have_dsp;
223   int regi;
224   int tid;
225 
226   if (regno >= mips_regnum (gdbarch)->fp0
227       && regno <= mips_regnum (gdbarch)->fp0 + 32)
228     is_fp = 1;
229   else if (regno == mips_regnum (gdbarch)->fp_control_status)
230     is_fp = 1;
231   else if (regno == mips_regnum (gdbarch)->fp_implementation_revision)
232     is_fp = 1;
233   else
234     is_fp = 0;
235 
236   /* DSP registers are optional and not a part of any set.  */
237   have_dsp = mips_regnum (gdbarch)->dspctl != -1;
238   if (!have_dsp)
239     is_dsp = 0;
240   else if (regno >= mips_regnum (gdbarch)->dspacc
241       && regno < mips_regnum (gdbarch)->dspacc + 6)
242     is_dsp = 1;
243   else if (regno == mips_regnum (gdbarch)->dspctl)
244     is_dsp = 1;
245   else
246     is_dsp = 0;
247 
248   tid = get_ptrace_pid (regcache_get_ptid (regcache));
249 
250   if (regno == -1 || (!is_fp && !is_dsp))
251     {
252       mips64_elf_gregset_t regs;
253 
254       if (ptrace (PTRACE_GETREGS, tid, 0L, (PTRACE_TYPE_ARG3) &regs) == -1)
255 	{
256 	  if (errno == EIO)
257 	    {
258 	      have_ptrace_regsets = 0;
259 	      return;
260 	    }
261 	  perror_with_name (_("Couldn't get registers"));
262 	}
263 
264       mips64_supply_gregset (regcache,
265 			     (const mips64_elf_gregset_t *) &regs);
266     }
267 
268   if (regno == -1 || is_fp)
269     {
270       mips64_elf_fpregset_t fp_regs;
271 
272       if (ptrace (PTRACE_GETFPREGS, tid, 0L,
273 		  (PTRACE_TYPE_ARG3) &fp_regs) == -1)
274 	{
275 	  if (errno == EIO)
276 	    {
277 	      have_ptrace_regsets = 0;
278 	      return;
279 	    }
280 	  perror_with_name (_("Couldn't get FP registers"));
281 	}
282 
283       mips64_supply_fpregset (regcache,
284 			      (const mips64_elf_fpregset_t *) &fp_regs);
285     }
286 
287   if (is_dsp)
288     super_fetch_registers (ops, regcache, regno);
289   else if (regno == -1 && have_dsp)
290     {
291       for (regi = mips_regnum (gdbarch)->dspacc;
292 	   regi < mips_regnum (gdbarch)->dspacc + 6;
293 	   regi++)
294 	super_fetch_registers (ops, regcache, regi);
295       super_fetch_registers (ops, regcache, mips_regnum (gdbarch)->dspctl);
296     }
297 }
298 
299 /* Store REGNO (or all registers if REGNO == -1) to the target
300    using PTRACE_SETREGS et al.  */
301 
302 static void
303 mips64_linux_regsets_store_registers (struct target_ops *ops,
304 				      struct regcache *regcache, int regno)
305 {
306   struct gdbarch *gdbarch = get_regcache_arch (regcache);
307   int is_fp, is_dsp;
308   int have_dsp;
309   int regi;
310   int tid;
311 
312   if (regno >= mips_regnum (gdbarch)->fp0
313       && regno <= mips_regnum (gdbarch)->fp0 + 32)
314     is_fp = 1;
315   else if (regno == mips_regnum (gdbarch)->fp_control_status)
316     is_fp = 1;
317   else if (regno == mips_regnum (gdbarch)->fp_implementation_revision)
318     is_fp = 1;
319   else
320     is_fp = 0;
321 
322   /* DSP registers are optional and not a part of any set.  */
323   have_dsp = mips_regnum (gdbarch)->dspctl != -1;
324   if (!have_dsp)
325     is_dsp = 0;
326   else if (regno >= mips_regnum (gdbarch)->dspacc
327       && regno < mips_regnum (gdbarch)->dspacc + 6)
328     is_dsp = 1;
329   else if (regno == mips_regnum (gdbarch)->dspctl)
330     is_dsp = 1;
331   else
332     is_dsp = 0;
333 
334   tid = get_ptrace_pid (regcache_get_ptid (regcache));
335 
336   if (regno == -1 || (!is_fp && !is_dsp))
337     {
338       mips64_elf_gregset_t regs;
339 
340       if (ptrace (PTRACE_GETREGS, tid, 0L, (PTRACE_TYPE_ARG3) &regs) == -1)
341 	perror_with_name (_("Couldn't get registers"));
342 
343       mips64_fill_gregset (regcache, &regs, regno);
344 
345       if (ptrace (PTRACE_SETREGS, tid, 0L, (PTRACE_TYPE_ARG3) &regs) == -1)
346 	perror_with_name (_("Couldn't set registers"));
347     }
348 
349   if (regno == -1 || is_fp)
350     {
351       mips64_elf_fpregset_t fp_regs;
352 
353       if (ptrace (PTRACE_GETFPREGS, tid, 0L,
354 		  (PTRACE_TYPE_ARG3) &fp_regs) == -1)
355 	perror_with_name (_("Couldn't get FP registers"));
356 
357       mips64_fill_fpregset (regcache, &fp_regs, regno);
358 
359       if (ptrace (PTRACE_SETFPREGS, tid, 0L,
360 		  (PTRACE_TYPE_ARG3) &fp_regs) == -1)
361 	perror_with_name (_("Couldn't set FP registers"));
362     }
363 
364   if (is_dsp)
365     super_store_registers (ops, regcache, regno);
366   else if (regno == -1 && have_dsp)
367     {
368       for (regi = mips_regnum (gdbarch)->dspacc;
369 	   regi < mips_regnum (gdbarch)->dspacc + 6;
370 	   regi++)
371 	super_store_registers (ops, regcache, regi);
372       super_store_registers (ops, regcache, mips_regnum (gdbarch)->dspctl);
373     }
374 }
375 
376 /* Fetch REGNO (or all registers if REGNO == -1) from the target
377    using any working method.  */
378 
379 static void
380 mips64_linux_fetch_registers (struct target_ops *ops,
381 			      struct regcache *regcache, int regnum)
382 {
383   /* Unless we already know that PTRACE_GETREGS does not work, try it.  */
384   if (have_ptrace_regsets)
385     mips64_linux_regsets_fetch_registers (ops, regcache, regnum);
386 
387   /* If we know, or just found out, that PTRACE_GETREGS does not work, fall
388      back to PTRACE_PEEKUSER.  */
389   if (!have_ptrace_regsets)
390     super_fetch_registers (ops, regcache, regnum);
391 }
392 
393 /* Store REGNO (or all registers if REGNO == -1) to the target
394    using any working method.  */
395 
396 static void
397 mips64_linux_store_registers (struct target_ops *ops,
398 			      struct regcache *regcache, int regnum)
399 {
400   /* Unless we already know that PTRACE_GETREGS does not work, try it.  */
401   if (have_ptrace_regsets)
402     mips64_linux_regsets_store_registers (ops, regcache, regnum);
403 
404   /* If we know, or just found out, that PTRACE_GETREGS does not work, fall
405      back to PTRACE_PEEKUSER.  */
406   if (!have_ptrace_regsets)
407     super_store_registers (ops, regcache, regnum);
408 }
409 
410 /* Return the address in the core dump or inferior of register
411    REGNO.  */
412 
413 static CORE_ADDR
414 mips_linux_register_u_offset (struct gdbarch *gdbarch, int regno, int store_p)
415 {
416   if (mips_abi_regsize (gdbarch) == 8)
417     return mips64_linux_register_addr (gdbarch, regno, store_p);
418   else
419     return mips_linux_register_addr (gdbarch, regno, store_p);
420 }
421 
422 static const struct target_desc *
423 mips_linux_read_description (struct target_ops *ops)
424 {
425   static int have_dsp = -1;
426 
427   if (have_dsp < 0)
428     {
429       int tid;
430 
431       tid = ptid_get_lwp (inferior_ptid);
432       if (tid == 0)
433 	tid = ptid_get_pid (inferior_ptid);
434 
435       errno = 0;
436       ptrace (PTRACE_PEEKUSER, tid, DSP_CONTROL, 0);
437       switch (errno)
438 	{
439 	case 0:
440 	  have_dsp = 1;
441 	  break;
442 	case EIO:
443 	  have_dsp = 0;
444 	  break;
445 	default:
446 	  perror_with_name (_("Couldn't check DSP support"));
447 	  break;
448 	}
449     }
450 
451   /* Report that target registers are a size we know for sure
452      that we can get from ptrace.  */
453   if (_MIPS_SIM == _ABIO32)
454     return have_dsp ? tdesc_mips_dsp_linux : tdesc_mips_linux;
455   else
456     return have_dsp ? tdesc_mips64_dsp_linux : tdesc_mips64_linux;
457 }
458 
459 /* -1 if the kernel and/or CPU do not support watch registers.
460     1 if watch_readback is valid and we can read style, num_valid
461       and the masks.
462     0 if we need to read the watch_readback.  */
463 
464 static int watch_readback_valid;
465 
466 /* Cached watch register read values.  */
467 
468 static struct pt_watch_regs watch_readback;
469 
470 static struct mips_watchpoint *current_watches;
471 
472 /*  The current set of watch register values for writing the
473     registers.  */
474 
475 static struct pt_watch_regs watch_mirror;
476 
477 static void
478 mips_show_dr (const char *func, CORE_ADDR addr,
479 	      int len, enum target_hw_bp_type type)
480 {
481   int i;
482 
483   puts_unfiltered (func);
484   if (addr || len)
485     printf_unfiltered (" (addr=%s, len=%d, type=%s)",
486 		       paddress (target_gdbarch (), addr), len,
487 		       type == hw_write ? "data-write"
488 		       : (type == hw_read ? "data-read"
489 			  : (type == hw_access ? "data-read/write"
490 			     : (type == hw_execute ? "instruction-execute"
491 				: "??unknown??"))));
492   puts_unfiltered (":\n");
493 
494   for (i = 0; i < MAX_DEBUG_REGISTER; i++)
495     printf_unfiltered ("\tDR%d: lo=%s, hi=%s\n", i,
496 		       paddress (target_gdbarch (),
497 				 mips_linux_watch_get_watchlo (&watch_mirror,
498 							       i)),
499 		       paddress (target_gdbarch (),
500 				 mips_linux_watch_get_watchhi (&watch_mirror,
501 							       i)));
502 }
503 
504 /* Target to_can_use_hw_breakpoint implementation.  Return 1 if we can
505    handle the specified watch type.  */
506 
507 static int
508 mips_linux_can_use_hw_breakpoint (struct target_ops *self,
509 				  enum bptype type,
510 				  int cnt, int ot)
511 {
512   int i;
513   uint32_t wanted_mask, irw_mask;
514 
515   if (!mips_linux_read_watch_registers (ptid_get_lwp (inferior_ptid),
516 					&watch_readback,
517 					&watch_readback_valid, 0))
518     return 0;
519 
520    switch (type)
521     {
522     case bp_hardware_watchpoint:
523       wanted_mask = W_MASK;
524       break;
525     case bp_read_watchpoint:
526       wanted_mask = R_MASK;
527       break;
528     case bp_access_watchpoint:
529       wanted_mask = R_MASK | W_MASK;
530       break;
531     default:
532       return 0;
533     }
534 
535   for (i = 0;
536        i < mips_linux_watch_get_num_valid (&watch_readback) && cnt;
537        i++)
538     {
539       irw_mask = mips_linux_watch_get_irw_mask (&watch_readback, i);
540       if ((irw_mask & wanted_mask) == wanted_mask)
541 	cnt--;
542     }
543   return (cnt == 0) ? 1 : 0;
544 }
545 
546 /* Target to_stopped_by_watchpoint implementation.  Return 1 if
547    stopped by watchpoint.  The watchhi R and W bits indicate the watch
548    register triggered.  */
549 
550 static int
551 mips_linux_stopped_by_watchpoint (struct target_ops *ops)
552 {
553   int n;
554   int num_valid;
555 
556   if (!mips_linux_read_watch_registers (ptid_get_lwp (inferior_ptid),
557 					&watch_readback,
558 					&watch_readback_valid, 1))
559     return 0;
560 
561   num_valid = mips_linux_watch_get_num_valid (&watch_readback);
562 
563   for (n = 0; n < MAX_DEBUG_REGISTER && n < num_valid; n++)
564     if (mips_linux_watch_get_watchhi (&watch_readback, n) & (R_MASK | W_MASK))
565       return 1;
566 
567   return 0;
568 }
569 
570 /* Target to_stopped_data_address implementation.  Set the address
571    where the watch triggered (if known).  Return 1 if the address was
572    known.  */
573 
574 static int
575 mips_linux_stopped_data_address (struct target_ops *t, CORE_ADDR *paddr)
576 {
577   /* On mips we don't know the low order 3 bits of the data address,
578      so we must return false.  */
579   return 0;
580 }
581 
582 /* Target to_region_ok_for_hw_watchpoint implementation.  Return 1 if
583    the specified region can be covered by the watch registers.  */
584 
585 static int
586 mips_linux_region_ok_for_hw_watchpoint (struct target_ops *self,
587 					CORE_ADDR addr, int len)
588 {
589   struct pt_watch_regs dummy_regs;
590   int i;
591 
592   if (!mips_linux_read_watch_registers (ptid_get_lwp (inferior_ptid),
593 					&watch_readback,
594 					&watch_readback_valid, 0))
595     return 0;
596 
597   dummy_regs = watch_readback;
598   /* Clear them out.  */
599   for (i = 0; i < mips_linux_watch_get_num_valid (&dummy_regs); i++)
600     mips_linux_watch_set_watchlo (&dummy_regs, i, 0);
601   return mips_linux_watch_try_one_watch (&dummy_regs, addr, len, 0);
602 }
603 
604 /* Write the mirrored watch register values for each thread.  */
605 
606 static int
607 write_watchpoint_regs (void)
608 {
609   struct lwp_info *lp;
610   int tid;
611 
612   ALL_LWPS (lp)
613     {
614       tid = ptid_get_lwp (lp->ptid);
615       if (ptrace (PTRACE_SET_WATCH_REGS, tid, &watch_mirror, NULL) == -1)
616 	perror_with_name (_("Couldn't write debug register"));
617     }
618   return 0;
619 }
620 
621 /* linux_nat new_thread implementation.  Write the mirrored watch
622  register values for the new thread.  */
623 
624 static void
625 mips_linux_new_thread (struct lwp_info *lp)
626 {
627   long tid = lp->ptid.lwp ();
628 
629   if (!mips_linux_read_watch_registers (tid,
630 					&watch_readback,
631 					&watch_readback_valid, 0))
632     return;
633 
634   if (ptrace (PTRACE_SET_WATCH_REGS, tid, &watch_mirror, NULL) == -1)
635     perror_with_name (_("Couldn't write debug register"));
636 }
637 
638 /* Target to_insert_watchpoint implementation.  Try to insert a new
639    watch.  Return zero on success.  */
640 
641 static int
642 mips_linux_insert_watchpoint (struct target_ops *self,
643 			      CORE_ADDR addr, int len,
644 			      enum target_hw_bp_type type,
645 			      struct expression *cond)
646 {
647   struct pt_watch_regs regs;
648   struct mips_watchpoint *new_watch;
649   struct mips_watchpoint **pw;
650 
651   int i;
652   int retval;
653 
654   if (!mips_linux_read_watch_registers (ptid_get_lwp (inferior_ptid),
655 					&watch_readback,
656 					&watch_readback_valid, 0))
657     return -1;
658 
659   if (len <= 0)
660     return -1;
661 
662   regs = watch_readback;
663   /* Add the current watches.  */
664   mips_linux_watch_populate_regs (current_watches, &regs);
665 
666   /* Now try to add the new watch.  */
667   if (!mips_linux_watch_try_one_watch (&regs, addr, len,
668 				       mips_linux_watch_type_to_irw (type)))
669     return -1;
670 
671   /* It fit.  Stick it on the end of the list.  */
672   new_watch = XNEW (struct mips_watchpoint);
673   new_watch->addr = addr;
674   new_watch->len = len;
675   new_watch->type = type;
676   new_watch->next = NULL;
677 
678   pw = &current_watches;
679   while (*pw != NULL)
680     pw = &(*pw)->next;
681   *pw = new_watch;
682 
683   watch_mirror = regs;
684   retval = write_watchpoint_regs ();
685 
686   if (show_debug_regs)
687     mips_show_dr ("insert_watchpoint", addr, len, type);
688 
689   return retval;
690 }
691 
692 /* Target to_remove_watchpoint implementation.  Try to remove a watch.
693    Return zero on success.  */
694 
695 static int
696 mips_linux_remove_watchpoint (struct target_ops *self,
697 			      CORE_ADDR addr, int len,
698 			      enum target_hw_bp_type type,
699 			      struct expression *cond)
700 {
701   int retval;
702   int deleted_one;
703 
704   struct mips_watchpoint **pw;
705   struct mips_watchpoint *w;
706 
707   /* Search for a known watch that matches.  Then unlink and free
708      it.  */
709   deleted_one = 0;
710   pw = &current_watches;
711   while ((w = *pw))
712     {
713       if (w->addr == addr && w->len == len && w->type == type)
714 	{
715 	  *pw = w->next;
716 	  xfree (w);
717 	  deleted_one = 1;
718 	  break;
719 	}
720       pw = &(w->next);
721     }
722 
723   if (!deleted_one)
724     return -1;  /* We don't know about it, fail doing nothing.  */
725 
726   /* At this point watch_readback is known to be valid because we
727      could not have added the watch without reading it.  */
728   gdb_assert (watch_readback_valid == 1);
729 
730   watch_mirror = watch_readback;
731   mips_linux_watch_populate_regs (current_watches, &watch_mirror);
732 
733   retval = write_watchpoint_regs ();
734 
735   if (show_debug_regs)
736     mips_show_dr ("remove_watchpoint", addr, len, type);
737 
738   return retval;
739 }
740 
741 /* Target to_close implementation.  Free any watches and call the
742    super implementation.  */
743 
744 static void
745 mips_linux_close (struct target_ops *self)
746 {
747   struct mips_watchpoint *w;
748   struct mips_watchpoint *nw;
749 
750   /* Clean out the current_watches list.  */
751   w = current_watches;
752   while (w)
753     {
754       nw = w->next;
755       xfree (w);
756       w = nw;
757     }
758   current_watches = NULL;
759 
760   if (super_close)
761     super_close (self);
762 }
763 
764 void _initialize_mips_linux_nat (void);
765 
766 void
767 _initialize_mips_linux_nat (void)
768 {
769   struct target_ops *t;
770 
771   add_setshow_boolean_cmd ("show-debug-regs", class_maintenance,
772 			   &show_debug_regs, _("\
773 Set whether to show variables that mirror the mips debug registers."), _("\
774 Show whether to show variables that mirror the mips debug registers."), _("\
775 Use \"on\" to enable, \"off\" to disable.\n\
776 If enabled, the debug registers values are shown when GDB inserts\n\
777 or removes a hardware breakpoint or watchpoint, and when the inferior\n\
778 triggers a breakpoint or watchpoint."),
779 			   NULL,
780 			   NULL,
781 			   &maintenance_set_cmdlist,
782 			   &maintenance_show_cmdlist);
783 
784   t = linux_trad_target (mips_linux_register_u_offset);
785 
786   super_close = t->to_close;
787   t->to_close = mips_linux_close;
788 
789   super_fetch_registers = t->to_fetch_registers;
790   super_store_registers = t->to_store_registers;
791 
792   t->to_fetch_registers = mips64_linux_fetch_registers;
793   t->to_store_registers = mips64_linux_store_registers;
794 
795   t->to_can_use_hw_breakpoint = mips_linux_can_use_hw_breakpoint;
796   t->to_remove_watchpoint = mips_linux_remove_watchpoint;
797   t->to_insert_watchpoint = mips_linux_insert_watchpoint;
798   t->to_stopped_by_watchpoint = mips_linux_stopped_by_watchpoint;
799   t->to_stopped_data_address = mips_linux_stopped_data_address;
800   t->to_region_ok_for_hw_watchpoint = mips_linux_region_ok_for_hw_watchpoint;
801 
802   t->to_read_description = mips_linux_read_description;
803 
804   linux_nat_add_target (t);
805   linux_nat_set_new_thread (t, mips_linux_new_thread);
806 
807   /* Initialize the standard target descriptions.  */
808   initialize_tdesc_mips_linux ();
809   initialize_tdesc_mips_dsp_linux ();
810   initialize_tdesc_mips64_linux ();
811   initialize_tdesc_mips64_dsp_linux ();
812 }
813