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1 | /* Native-dependent code for GNU/Linux i386. | |
2 | ||
3 | Copyright (C) 1999-2020 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 "inferior.h" | |
22 | #include "gdbcore.h" | |
23 | #include "regcache.h" | |
24 | #include "elf/common.h" | |
25 | #include "nat/gdb_ptrace.h" | |
26 | #include <sys/uio.h> | |
27 | #include "gregset.h" | |
28 | #include "gdb_proc_service.h" | |
29 | ||
30 | #include "i386-linux-nat.h" | |
31 | #include "i387-tdep.h" | |
32 | #include "i386-tdep.h" | |
33 | #include "i386-linux-tdep.h" | |
34 | #include "gdbsupport/x86-xstate.h" | |
35 | ||
36 | #include "x86-linux-nat.h" | |
37 | #include "nat/linux-ptrace.h" | |
38 | #include "inf-ptrace.h" | |
39 | ||
40 | struct i386_linux_nat_target final : public x86_linux_nat_target | |
41 | { | |
42 | /* Add our register access methods. */ | |
43 | void fetch_registers (struct regcache *, int) override; | |
44 | void store_registers (struct regcache *, int) override; | |
45 | ||
46 | /* Override the default ptrace resume method. */ | |
47 | void low_resume (ptid_t ptid, int step, enum gdb_signal sig) override; | |
48 | }; | |
49 | ||
50 | static i386_linux_nat_target the_i386_linux_nat_target; | |
51 | ||
52 | /* The register sets used in GNU/Linux ELF core-dumps are identical to | |
53 | the register sets in `struct user' that is used for a.out | |
54 | core-dumps, and is also used by `ptrace'. The corresponding types | |
55 | are `elf_gregset_t' for the general-purpose registers (with | |
56 | `elf_greg_t' the type of a single GP register) and `elf_fpregset_t' | |
57 | for the floating-point registers. | |
58 | ||
59 | Those types used to be available under the names `gregset_t' and | |
60 | `fpregset_t' too, and this file used those names in the past. But | |
61 | those names are now used for the register sets used in the | |
62 | `mcontext_t' type, and have a different size and layout. */ | |
63 | ||
64 | /* Which ptrace request retrieves which registers? | |
65 | These apply to the corresponding SET requests as well. */ | |
66 | ||
67 | #define GETREGS_SUPPLIES(regno) \ | |
68 | ((0 <= (regno) && (regno) <= 15) || (regno) == I386_LINUX_ORIG_EAX_REGNUM) | |
69 | ||
70 | #define GETFPXREGS_SUPPLIES(regno) \ | |
71 | (I386_ST0_REGNUM <= (regno) && (regno) < I386_SSE_NUM_REGS) | |
72 | ||
73 | #define GETXSTATEREGS_SUPPLIES(regno) \ | |
74 | (I386_ST0_REGNUM <= (regno) && (regno) < I386_PKEYS_NUM_REGS) | |
75 | ||
76 | /* Does the current host support the GETREGS request? */ | |
77 | int have_ptrace_getregs = | |
78 | #ifdef HAVE_PTRACE_GETREGS | |
79 | 1 | |
80 | #else | |
81 | 0 | |
82 | #endif | |
83 | ; | |
84 | ||
85 | /* Does the current host support the GETFPXREGS request? The header | |
86 | file may or may not define it, and even if it is defined, the | |
87 | kernel will return EIO if it's running on a pre-SSE processor. | |
88 | ||
89 | My instinct is to attach this to some architecture- or | |
90 | target-specific data structure, but really, a particular GDB | |
91 | process can only run on top of one kernel at a time. So it's okay | |
92 | for this to be a simple variable. */ | |
93 | int have_ptrace_getfpxregs = | |
94 | #ifdef HAVE_PTRACE_GETFPXREGS | |
95 | -1 | |
96 | #else | |
97 | 0 | |
98 | #endif | |
99 | ; | |
100 | \f | |
101 | ||
102 | /* Accessing registers through the U area, one at a time. */ | |
103 | ||
104 | /* Fetch one register. */ | |
105 | ||
106 | static void | |
107 | fetch_register (struct regcache *regcache, int regno) | |
108 | { | |
109 | pid_t tid; | |
110 | int val; | |
111 | ||
112 | gdb_assert (!have_ptrace_getregs); | |
113 | if (i386_linux_gregset_reg_offset[regno] == -1) | |
114 | { | |
115 | regcache->raw_supply (regno, NULL); | |
116 | return; | |
117 | } | |
118 | ||
119 | tid = get_ptrace_pid (regcache->ptid ()); | |
120 | ||
121 | errno = 0; | |
122 | val = ptrace (PTRACE_PEEKUSER, tid, | |
123 | i386_linux_gregset_reg_offset[regno], 0); | |
124 | if (errno != 0) | |
125 | error (_("Couldn't read register %s (#%d): %s."), | |
126 | gdbarch_register_name (regcache->arch (), regno), | |
127 | regno, safe_strerror (errno)); | |
128 | ||
129 | regcache->raw_supply (regno, &val); | |
130 | } | |
131 | ||
132 | /* Store one register. */ | |
133 | ||
134 | static void | |
135 | store_register (const struct regcache *regcache, int regno) | |
136 | { | |
137 | pid_t tid; | |
138 | int val; | |
139 | ||
140 | gdb_assert (!have_ptrace_getregs); | |
141 | if (i386_linux_gregset_reg_offset[regno] == -1) | |
142 | return; | |
143 | ||
144 | tid = get_ptrace_pid (regcache->ptid ()); | |
145 | ||
146 | errno = 0; | |
147 | regcache->raw_collect (regno, &val); | |
148 | ptrace (PTRACE_POKEUSER, tid, | |
149 | i386_linux_gregset_reg_offset[regno], val); | |
150 | if (errno != 0) | |
151 | error (_("Couldn't write register %s (#%d): %s."), | |
152 | gdbarch_register_name (regcache->arch (), regno), | |
153 | regno, safe_strerror (errno)); | |
154 | } | |
155 | \f | |
156 | ||
157 | /* Transfering the general-purpose registers between GDB, inferiors | |
158 | and core files. */ | |
159 | ||
160 | /* Fill GDB's register array with the general-purpose register values | |
161 | in *GREGSETP. */ | |
162 | ||
163 | void | |
164 | supply_gregset (struct regcache *regcache, const elf_gregset_t *gregsetp) | |
165 | { | |
166 | const gdb_byte *regp = (const gdb_byte *) gregsetp; | |
167 | int i; | |
168 | ||
169 | for (i = 0; i < I386_NUM_GREGS; i++) | |
170 | regcache->raw_supply (i, regp + i386_linux_gregset_reg_offset[i]); | |
171 | ||
172 | if (I386_LINUX_ORIG_EAX_REGNUM | |
173 | < gdbarch_num_regs (regcache->arch ())) | |
174 | regcache->raw_supply | |
175 | (I386_LINUX_ORIG_EAX_REGNUM, | |
176 | regp + i386_linux_gregset_reg_offset[I386_LINUX_ORIG_EAX_REGNUM]); | |
177 | } | |
178 | ||
179 | /* Fill register REGNO (if it is a general-purpose register) in | |
180 | *GREGSETPS with the value in GDB's register array. If REGNO is -1, | |
181 | do this for all registers. */ | |
182 | ||
183 | void | |
184 | fill_gregset (const struct regcache *regcache, | |
185 | elf_gregset_t *gregsetp, int regno) | |
186 | { | |
187 | gdb_byte *regp = (gdb_byte *) gregsetp; | |
188 | int i; | |
189 | ||
190 | for (i = 0; i < I386_NUM_GREGS; i++) | |
191 | if (regno == -1 || regno == i) | |
192 | regcache->raw_collect (i, regp + i386_linux_gregset_reg_offset[i]); | |
193 | ||
194 | if ((regno == -1 || regno == I386_LINUX_ORIG_EAX_REGNUM) | |
195 | && I386_LINUX_ORIG_EAX_REGNUM | |
196 | < gdbarch_num_regs (regcache->arch ())) | |
197 | regcache->raw_collect | |
198 | (I386_LINUX_ORIG_EAX_REGNUM, | |
199 | regp + i386_linux_gregset_reg_offset[I386_LINUX_ORIG_EAX_REGNUM]); | |
200 | } | |
201 | ||
202 | #ifdef HAVE_PTRACE_GETREGS | |
203 | ||
204 | /* Fetch all general-purpose registers from process/thread TID and | |
205 | store their values in GDB's register array. */ | |
206 | ||
207 | static void | |
208 | fetch_regs (struct regcache *regcache, int tid) | |
209 | { | |
210 | elf_gregset_t regs; | |
211 | elf_gregset_t *regs_p = ®s; | |
212 | ||
213 | if (ptrace (PTRACE_GETREGS, tid, 0, (int) ®s) < 0) | |
214 | { | |
215 | if (errno == EIO) | |
216 | { | |
217 | /* The kernel we're running on doesn't support the GETREGS | |
218 | request. Reset `have_ptrace_getregs'. */ | |
219 | have_ptrace_getregs = 0; | |
220 | return; | |
221 | } | |
222 | ||
223 | perror_with_name (_("Couldn't get registers")); | |
224 | } | |
225 | ||
226 | supply_gregset (regcache, (const elf_gregset_t *) regs_p); | |
227 | } | |
228 | ||
229 | /* Store all valid general-purpose registers in GDB's register array | |
230 | into the process/thread specified by TID. */ | |
231 | ||
232 | static void | |
233 | store_regs (const struct regcache *regcache, int tid, int regno) | |
234 | { | |
235 | elf_gregset_t regs; | |
236 | ||
237 | if (ptrace (PTRACE_GETREGS, tid, 0, (int) ®s) < 0) | |
238 | perror_with_name (_("Couldn't get registers")); | |
239 | ||
240 | fill_gregset (regcache, ®s, regno); | |
241 | ||
242 | if (ptrace (PTRACE_SETREGS, tid, 0, (int) ®s) < 0) | |
243 | perror_with_name (_("Couldn't write registers")); | |
244 | } | |
245 | ||
246 | #else | |
247 | ||
248 | static void fetch_regs (struct regcache *regcache, int tid) {} | |
249 | static void store_regs (const struct regcache *regcache, int tid, int regno) {} | |
250 | ||
251 | #endif | |
252 | \f | |
253 | ||
254 | /* Transfering floating-point registers between GDB, inferiors and cores. */ | |
255 | ||
256 | /* Fill GDB's register array with the floating-point register values in | |
257 | *FPREGSETP. */ | |
258 | ||
259 | void | |
260 | supply_fpregset (struct regcache *regcache, const elf_fpregset_t *fpregsetp) | |
261 | { | |
262 | i387_supply_fsave (regcache, -1, fpregsetp); | |
263 | } | |
264 | ||
265 | /* Fill register REGNO (if it is a floating-point register) in | |
266 | *FPREGSETP with the value in GDB's register array. If REGNO is -1, | |
267 | do this for all registers. */ | |
268 | ||
269 | void | |
270 | fill_fpregset (const struct regcache *regcache, | |
271 | elf_fpregset_t *fpregsetp, int regno) | |
272 | { | |
273 | i387_collect_fsave (regcache, regno, fpregsetp); | |
274 | } | |
275 | ||
276 | #ifdef HAVE_PTRACE_GETREGS | |
277 | ||
278 | /* Fetch all floating-point registers from process/thread TID and store | |
279 | thier values in GDB's register array. */ | |
280 | ||
281 | static void | |
282 | fetch_fpregs (struct regcache *regcache, int tid) | |
283 | { | |
284 | elf_fpregset_t fpregs; | |
285 | ||
286 | if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0) | |
287 | perror_with_name (_("Couldn't get floating point status")); | |
288 | ||
289 | supply_fpregset (regcache, (const elf_fpregset_t *) &fpregs); | |
290 | } | |
291 | ||
292 | /* Store all valid floating-point registers in GDB's register array | |
293 | into the process/thread specified by TID. */ | |
294 | ||
295 | static void | |
296 | store_fpregs (const struct regcache *regcache, int tid, int regno) | |
297 | { | |
298 | elf_fpregset_t fpregs; | |
299 | ||
300 | if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0) | |
301 | perror_with_name (_("Couldn't get floating point status")); | |
302 | ||
303 | fill_fpregset (regcache, &fpregs, regno); | |
304 | ||
305 | if (ptrace (PTRACE_SETFPREGS, tid, 0, (int) &fpregs) < 0) | |
306 | perror_with_name (_("Couldn't write floating point status")); | |
307 | } | |
308 | ||
309 | #else | |
310 | ||
311 | static void | |
312 | fetch_fpregs (struct regcache *regcache, int tid) | |
313 | { | |
314 | } | |
315 | ||
316 | static void | |
317 | store_fpregs (const struct regcache *regcache, int tid, int regno) | |
318 | { | |
319 | } | |
320 | ||
321 | #endif | |
322 | \f | |
323 | ||
324 | /* Transfering floating-point and SSE registers to and from GDB. */ | |
325 | ||
326 | /* Fetch all registers covered by the PTRACE_GETREGSET request from | |
327 | process/thread TID and store their values in GDB's register array. | |
328 | Return non-zero if successful, zero otherwise. */ | |
329 | ||
330 | static int | |
331 | fetch_xstateregs (struct regcache *regcache, int tid) | |
332 | { | |
333 | char xstateregs[X86_XSTATE_MAX_SIZE]; | |
334 | struct iovec iov; | |
335 | ||
336 | if (have_ptrace_getregset != TRIBOOL_TRUE) | |
337 | return 0; | |
338 | ||
339 | iov.iov_base = xstateregs; | |
340 | iov.iov_len = sizeof(xstateregs); | |
341 | if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE, | |
342 | &iov) < 0) | |
343 | perror_with_name (_("Couldn't read extended state status")); | |
344 | ||
345 | i387_supply_xsave (regcache, -1, xstateregs); | |
346 | return 1; | |
347 | } | |
348 | ||
349 | /* Store all valid registers in GDB's register array covered by the | |
350 | PTRACE_SETREGSET request into the process/thread specified by TID. | |
351 | Return non-zero if successful, zero otherwise. */ | |
352 | ||
353 | static int | |
354 | store_xstateregs (const struct regcache *regcache, int tid, int regno) | |
355 | { | |
356 | char xstateregs[X86_XSTATE_MAX_SIZE]; | |
357 | struct iovec iov; | |
358 | ||
359 | if (have_ptrace_getregset != TRIBOOL_TRUE) | |
360 | return 0; | |
361 | ||
362 | iov.iov_base = xstateregs; | |
363 | iov.iov_len = sizeof(xstateregs); | |
364 | if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE, | |
365 | &iov) < 0) | |
366 | perror_with_name (_("Couldn't read extended state status")); | |
367 | ||
368 | i387_collect_xsave (regcache, regno, xstateregs, 0); | |
369 | ||
370 | if (ptrace (PTRACE_SETREGSET, tid, (unsigned int) NT_X86_XSTATE, | |
371 | (int) &iov) < 0) | |
372 | perror_with_name (_("Couldn't write extended state status")); | |
373 | ||
374 | return 1; | |
375 | } | |
376 | ||
377 | #ifdef HAVE_PTRACE_GETFPXREGS | |
378 | ||
379 | /* Fetch all registers covered by the PTRACE_GETFPXREGS request from | |
380 | process/thread TID and store their values in GDB's register array. | |
381 | Return non-zero if successful, zero otherwise. */ | |
382 | ||
383 | static int | |
384 | fetch_fpxregs (struct regcache *regcache, int tid) | |
385 | { | |
386 | elf_fpxregset_t fpxregs; | |
387 | ||
388 | if (! have_ptrace_getfpxregs) | |
389 | return 0; | |
390 | ||
391 | if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0) | |
392 | { | |
393 | if (errno == EIO) | |
394 | { | |
395 | have_ptrace_getfpxregs = 0; | |
396 | return 0; | |
397 | } | |
398 | ||
399 | perror_with_name (_("Couldn't read floating-point and SSE registers")); | |
400 | } | |
401 | ||
402 | i387_supply_fxsave (regcache, -1, (const elf_fpxregset_t *) &fpxregs); | |
403 | return 1; | |
404 | } | |
405 | ||
406 | /* Store all valid registers in GDB's register array covered by the | |
407 | PTRACE_SETFPXREGS request into the process/thread specified by TID. | |
408 | Return non-zero if successful, zero otherwise. */ | |
409 | ||
410 | static int | |
411 | store_fpxregs (const struct regcache *regcache, int tid, int regno) | |
412 | { | |
413 | elf_fpxregset_t fpxregs; | |
414 | ||
415 | if (! have_ptrace_getfpxregs) | |
416 | return 0; | |
417 | ||
418 | if (ptrace (PTRACE_GETFPXREGS, tid, 0, &fpxregs) == -1) | |
419 | { | |
420 | if (errno == EIO) | |
421 | { | |
422 | have_ptrace_getfpxregs = 0; | |
423 | return 0; | |
424 | } | |
425 | ||
426 | perror_with_name (_("Couldn't read floating-point and SSE registers")); | |
427 | } | |
428 | ||
429 | i387_collect_fxsave (regcache, regno, &fpxregs); | |
430 | ||
431 | if (ptrace (PTRACE_SETFPXREGS, tid, 0, &fpxregs) == -1) | |
432 | perror_with_name (_("Couldn't write floating-point and SSE registers")); | |
433 | ||
434 | return 1; | |
435 | } | |
436 | ||
437 | #else | |
438 | ||
439 | static int | |
440 | fetch_fpxregs (struct regcache *regcache, int tid) | |
441 | { | |
442 | return 0; | |
443 | } | |
444 | ||
445 | static int | |
446 | store_fpxregs (const struct regcache *regcache, int tid, int regno) | |
447 | { | |
448 | return 0; | |
449 | } | |
450 | ||
451 | #endif /* HAVE_PTRACE_GETFPXREGS */ | |
452 | \f | |
453 | ||
454 | /* Transferring arbitrary registers between GDB and inferior. */ | |
455 | ||
456 | /* Fetch register REGNO from the child process. If REGNO is -1, do | |
457 | this for all registers (including the floating point and SSE | |
458 | registers). */ | |
459 | ||
460 | void | |
461 | i386_linux_nat_target::fetch_registers (struct regcache *regcache, int regno) | |
462 | { | |
463 | pid_t tid; | |
464 | ||
465 | /* Use the old method of peeking around in `struct user' if the | |
466 | GETREGS request isn't available. */ | |
467 | if (!have_ptrace_getregs) | |
468 | { | |
469 | int i; | |
470 | ||
471 | for (i = 0; i < gdbarch_num_regs (regcache->arch ()); i++) | |
472 | if (regno == -1 || regno == i) | |
473 | fetch_register (regcache, i); | |
474 | ||
475 | return; | |
476 | } | |
477 | ||
478 | tid = get_ptrace_pid (regcache->ptid ()); | |
479 | ||
480 | /* Use the PTRACE_GETFPXREGS request whenever possible, since it | |
481 | transfers more registers in one system call, and we'll cache the | |
482 | results. But remember that fetch_fpxregs can fail, and return | |
483 | zero. */ | |
484 | if (regno == -1) | |
485 | { | |
486 | fetch_regs (regcache, tid); | |
487 | ||
488 | /* The call above might reset `have_ptrace_getregs'. */ | |
489 | if (!have_ptrace_getregs) | |
490 | { | |
491 | fetch_registers (regcache, regno); | |
492 | return; | |
493 | } | |
494 | ||
495 | if (fetch_xstateregs (regcache, tid)) | |
496 | return; | |
497 | if (fetch_fpxregs (regcache, tid)) | |
498 | return; | |
499 | fetch_fpregs (regcache, tid); | |
500 | return; | |
501 | } | |
502 | ||
503 | if (GETREGS_SUPPLIES (regno)) | |
504 | { | |
505 | fetch_regs (regcache, tid); | |
506 | return; | |
507 | } | |
508 | ||
509 | if (GETXSTATEREGS_SUPPLIES (regno)) | |
510 | { | |
511 | if (fetch_xstateregs (regcache, tid)) | |
512 | return; | |
513 | } | |
514 | ||
515 | if (GETFPXREGS_SUPPLIES (regno)) | |
516 | { | |
517 | if (fetch_fpxregs (regcache, tid)) | |
518 | return; | |
519 | ||
520 | /* Either our processor or our kernel doesn't support the SSE | |
521 | registers, so read the FP registers in the traditional way, | |
522 | and fill the SSE registers with dummy values. It would be | |
523 | more graceful to handle differences in the register set using | |
524 | gdbarch. Until then, this will at least make things work | |
525 | plausibly. */ | |
526 | fetch_fpregs (regcache, tid); | |
527 | return; | |
528 | } | |
529 | ||
530 | internal_error (__FILE__, __LINE__, | |
531 | _("Got request for bad register number %d."), regno); | |
532 | } | |
533 | ||
534 | /* Store register REGNO back into the child process. If REGNO is -1, | |
535 | do this for all registers (including the floating point and SSE | |
536 | registers). */ | |
537 | void | |
538 | i386_linux_nat_target::store_registers (struct regcache *regcache, int regno) | |
539 | { | |
540 | pid_t tid; | |
541 | ||
542 | /* Use the old method of poking around in `struct user' if the | |
543 | SETREGS request isn't available. */ | |
544 | if (!have_ptrace_getregs) | |
545 | { | |
546 | int i; | |
547 | ||
548 | for (i = 0; i < gdbarch_num_regs (regcache->arch ()); i++) | |
549 | if (regno == -1 || regno == i) | |
550 | store_register (regcache, i); | |
551 | ||
552 | return; | |
553 | } | |
554 | ||
555 | tid = get_ptrace_pid (regcache->ptid ()); | |
556 | ||
557 | /* Use the PTRACE_SETFPXREGS requests whenever possible, since it | |
558 | transfers more registers in one system call. But remember that | |
559 | store_fpxregs can fail, and return zero. */ | |
560 | if (regno == -1) | |
561 | { | |
562 | store_regs (regcache, tid, regno); | |
563 | if (store_xstateregs (regcache, tid, regno)) | |
564 | return; | |
565 | if (store_fpxregs (regcache, tid, regno)) | |
566 | return; | |
567 | store_fpregs (regcache, tid, regno); | |
568 | return; | |
569 | } | |
570 | ||
571 | if (GETREGS_SUPPLIES (regno)) | |
572 | { | |
573 | store_regs (regcache, tid, regno); | |
574 | return; | |
575 | } | |
576 | ||
577 | if (GETXSTATEREGS_SUPPLIES (regno)) | |
578 | { | |
579 | if (store_xstateregs (regcache, tid, regno)) | |
580 | return; | |
581 | } | |
582 | ||
583 | if (GETFPXREGS_SUPPLIES (regno)) | |
584 | { | |
585 | if (store_fpxregs (regcache, tid, regno)) | |
586 | return; | |
587 | ||
588 | /* Either our processor or our kernel doesn't support the SSE | |
589 | registers, so just write the FP registers in the traditional | |
590 | way. */ | |
591 | store_fpregs (regcache, tid, regno); | |
592 | return; | |
593 | } | |
594 | ||
595 | internal_error (__FILE__, __LINE__, | |
596 | _("Got request to store bad register number %d."), regno); | |
597 | } | |
598 | \f | |
599 | ||
600 | /* Called by libthread_db. Returns a pointer to the thread local | |
601 | storage (or its descriptor). */ | |
602 | ||
603 | ps_err_e | |
604 | ps_get_thread_area (struct ps_prochandle *ph, | |
605 | lwpid_t lwpid, int idx, void **base) | |
606 | { | |
607 | unsigned int base_addr; | |
608 | ps_err_e result; | |
609 | ||
610 | result = x86_linux_get_thread_area (lwpid, (void *) idx, &base_addr); | |
611 | ||
612 | if (result == PS_OK) | |
613 | *(int *) base = base_addr; | |
614 | ||
615 | return result; | |
616 | } | |
617 | \f | |
618 | ||
619 | /* The instruction for a GNU/Linux system call is: | |
620 | int $0x80 | |
621 | or 0xcd 0x80. */ | |
622 | ||
623 | static const unsigned char linux_syscall[] = { 0xcd, 0x80 }; | |
624 | ||
625 | #define LINUX_SYSCALL_LEN (sizeof linux_syscall) | |
626 | ||
627 | /* The system call number is stored in the %eax register. */ | |
628 | #define LINUX_SYSCALL_REGNUM I386_EAX_REGNUM | |
629 | ||
630 | /* We are specifically interested in the sigreturn and rt_sigreturn | |
631 | system calls. */ | |
632 | ||
633 | #ifndef SYS_sigreturn | |
634 | #define SYS_sigreturn 0x77 | |
635 | #endif | |
636 | #ifndef SYS_rt_sigreturn | |
637 | #define SYS_rt_sigreturn 0xad | |
638 | #endif | |
639 | ||
640 | /* Offset to saved processor flags, from <asm/sigcontext.h>. */ | |
641 | #define LINUX_SIGCONTEXT_EFLAGS_OFFSET (64) | |
642 | ||
643 | /* Resume execution of the inferior process. | |
644 | If STEP is nonzero, single-step it. | |
645 | If SIGNAL is nonzero, give it that signal. */ | |
646 | ||
647 | void | |
648 | i386_linux_nat_target::low_resume (ptid_t ptid, int step, enum gdb_signal signal) | |
649 | { | |
650 | int pid = ptid.lwp (); | |
651 | int request; | |
652 | ||
653 | if (catch_syscall_enabled () > 0) | |
654 | request = PTRACE_SYSCALL; | |
655 | else | |
656 | request = PTRACE_CONT; | |
657 | ||
658 | if (step) | |
659 | { | |
660 | struct regcache *regcache = get_thread_regcache (this, ptid); | |
661 | struct gdbarch *gdbarch = regcache->arch (); | |
662 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); | |
663 | ULONGEST pc; | |
664 | gdb_byte buf[LINUX_SYSCALL_LEN]; | |
665 | ||
666 | request = PTRACE_SINGLESTEP; | |
667 | ||
668 | regcache_cooked_read_unsigned (regcache, | |
669 | gdbarch_pc_regnum (gdbarch), &pc); | |
670 | ||
671 | /* Returning from a signal trampoline is done by calling a | |
672 | special system call (sigreturn or rt_sigreturn, see | |
673 | i386-linux-tdep.c for more information). This system call | |
674 | restores the registers that were saved when the signal was | |
675 | raised, including %eflags. That means that single-stepping | |
676 | won't work. Instead, we'll have to modify the signal context | |
677 | that's about to be restored, and set the trace flag there. */ | |
678 | ||
679 | /* First check if PC is at a system call. */ | |
680 | if (target_read_memory (pc, buf, LINUX_SYSCALL_LEN) == 0 | |
681 | && memcmp (buf, linux_syscall, LINUX_SYSCALL_LEN) == 0) | |
682 | { | |
683 | ULONGEST syscall; | |
684 | regcache_cooked_read_unsigned (regcache, | |
685 | LINUX_SYSCALL_REGNUM, &syscall); | |
686 | ||
687 | /* Then check the system call number. */ | |
688 | if (syscall == SYS_sigreturn || syscall == SYS_rt_sigreturn) | |
689 | { | |
690 | ULONGEST sp, addr; | |
691 | unsigned long int eflags; | |
692 | ||
693 | regcache_cooked_read_unsigned (regcache, I386_ESP_REGNUM, &sp); | |
694 | if (syscall == SYS_rt_sigreturn) | |
695 | addr = read_memory_unsigned_integer (sp + 8, 4, byte_order) | |
696 | + 20; | |
697 | else | |
698 | addr = sp; | |
699 | ||
700 | /* Set the trace flag in the context that's about to be | |
701 | restored. */ | |
702 | addr += LINUX_SIGCONTEXT_EFLAGS_OFFSET; | |
703 | read_memory (addr, (gdb_byte *) &eflags, 4); | |
704 | eflags |= 0x0100; | |
705 | write_memory (addr, (gdb_byte *) &eflags, 4); | |
706 | } | |
707 | } | |
708 | } | |
709 | ||
710 | if (ptrace (request, pid, 0, gdb_signal_to_host (signal)) == -1) | |
711 | perror_with_name (("ptrace")); | |
712 | } | |
713 | ||
714 | void _initialize_i386_linux_nat (); | |
715 | void | |
716 | _initialize_i386_linux_nat () | |
717 | { | |
718 | linux_target = &the_i386_linux_nat_target; | |
719 | ||
720 | /* Add the target. */ | |
721 | add_inf_child_target (linux_target); | |
722 | } |