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Linux 4.2.2
[linux/fpc-iii.git] / arch / s390 / kernel / signal.c
blobc551f22ce066466ebc6d6666b85a459716842683
1 /*
2 * Copyright IBM Corp. 1999, 2006
3 * Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
4 *
5 * Based on Intel version
6 *
7 * Copyright (C) 1991, 1992 Linus Torvalds
8 *
9 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
10 */
11
12 #include <linux/sched.h>
13 #include <linux/mm.h>
14 #include <linux/smp.h>
15 #include <linux/kernel.h>
16 #include <linux/signal.h>
17 #include <linux/errno.h>
18 #include <linux/wait.h>
19 #include <linux/ptrace.h>
20 #include <linux/unistd.h>
21 #include <linux/stddef.h>
22 #include <linux/tty.h>
23 #include <linux/personality.h>
24 #include <linux/binfmts.h>
25 #include <linux/tracehook.h>
26 #include <linux/syscalls.h>
27 #include <linux/compat.h>
28 #include <asm/ucontext.h>
29 #include <asm/uaccess.h>
30 #include <asm/lowcore.h>
31 #include <asm/switch_to.h>
32 #include "entry.h"
33
34 /*
35 * Layout of an old-style signal-frame:
36 * -----------------------------------------
37 * | save area (_SIGNAL_FRAMESIZE) |
38 * -----------------------------------------
39 * | struct sigcontext |
40 * | oldmask |
41 * | _sigregs * |
42 * -----------------------------------------
43 * | _sigregs with |
44 * | _s390_regs_common |
45 * | _s390_fp_regs |
46 * -----------------------------------------
47 * | int signo |
48 * -----------------------------------------
49 * | _sigregs_ext with |
50 * | gprs_high 64 byte (opt) |
51 * | vxrs_low 128 byte (opt) |
52 * | vxrs_high 256 byte (opt) |
53 * | reserved 128 byte (opt) |
54 * -----------------------------------------
55 * | __u16 svc_insn |
56 * -----------------------------------------
57 * The svc_insn entry with the sigreturn system call opcode does not
58 * have a fixed position and moves if gprs_high or vxrs exist.
59 * Future extensions will be added to _sigregs_ext.
60 */
61 struct sigframe
62 {
63 __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
64 struct sigcontext sc;
65 _sigregs sregs;
66 int signo;
67 _sigregs_ext sregs_ext;
68 __u16 svc_insn; /* Offset of svc_insn is NOT fixed! */
69 };
70
71 /*
72 * Layout of an rt signal-frame:
73 * -----------------------------------------
74 * | save area (_SIGNAL_FRAMESIZE) |
75 * -----------------------------------------
76 * | svc __NR_rt_sigreturn 2 byte |
77 * -----------------------------------------
78 * | struct siginfo |
79 * -----------------------------------------
80 * | struct ucontext_extended with |
81 * | unsigned long uc_flags |
82 * | struct ucontext *uc_link |
83 * | stack_t uc_stack |
84 * | _sigregs uc_mcontext with |
85 * | _s390_regs_common |
86 * | _s390_fp_regs |
87 * | sigset_t uc_sigmask |
88 * | _sigregs_ext uc_mcontext_ext |
89 * | gprs_high 64 byte (opt) |
90 * | vxrs_low 128 byte (opt) |
91 * | vxrs_high 256 byte (opt)|
92 * | reserved 128 byte (opt) |
93 * -----------------------------------------
94 * Future extensions will be added to _sigregs_ext.
95 */
96 struct rt_sigframe
97 {
98 __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
99 __u16 svc_insn;
100 struct siginfo info;
101 struct ucontext_extended uc;
102 };
103
104 /* Store registers needed to create the signal frame */
105 static void store_sigregs(void)
106 {
107 save_access_regs(current->thread.acrs);
108 save_fp_ctl(&current->thread.fp_regs.fpc);
109 if (current->thread.vxrs) {
110 int i;
111
112 save_vx_regs(current->thread.vxrs);
113 for (i = 0; i < __NUM_FPRS; i++)
114 current->thread.fp_regs.fprs[i] =
115 *(freg_t *)(current->thread.vxrs + i);
116 } else
117 save_fp_regs(current->thread.fp_regs.fprs);
118 }
119
120 /* Load registers after signal return */
121 static void load_sigregs(void)
122 {
123 restore_access_regs(current->thread.acrs);
124 /* restore_fp_ctl is done in restore_sigregs */
125 if (current->thread.vxrs) {
126 int i;
127
128 for (i = 0; i < __NUM_FPRS; i++)
129 *(freg_t *)(current->thread.vxrs + i) =
130 current->thread.fp_regs.fprs[i];
131 restore_vx_regs(current->thread.vxrs);
132 } else
133 restore_fp_regs(current->thread.fp_regs.fprs);
134 }
135
136 /* Returns non-zero on fault. */
137 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
138 {
139 _sigregs user_sregs;
140
141 /* Copy a 'clean' PSW mask to the user to avoid leaking
142 information about whether PER is currently on. */
143 user_sregs.regs.psw.mask = PSW_USER_BITS |
144 (regs->psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
145 user_sregs.regs.psw.addr = regs->psw.addr;
146 memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
147 memcpy(&user_sregs.regs.acrs, current->thread.acrs,
148 sizeof(user_sregs.regs.acrs));
149 memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
150 sizeof(user_sregs.fpregs));
151 if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs)))
152 return -EFAULT;
153 return 0;
154 }
155
156 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
157 {
158 _sigregs user_sregs;
159
160 /* Alwys make any pending restarted system call return -EINTR */
161 current->restart_block.fn = do_no_restart_syscall;
162
163 if (__copy_from_user(&user_sregs, sregs, sizeof(user_sregs)))
164 return -EFAULT;
165
166 if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI))
167 return -EINVAL;
168
169 /* Loading the floating-point-control word can fail. Do that first. */
170 if (restore_fp_ctl(&user_sregs.fpregs.fpc))
171 return -EINVAL;
172
173 /* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
174 regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) |
175 (user_sregs.regs.psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
176 /* Check for invalid user address space control. */
177 if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
178 regs->psw.mask = PSW_ASC_PRIMARY |
179 (regs->psw.mask & ~PSW_MASK_ASC);
180 /* Check for invalid amode */
181 if (regs->psw.mask & PSW_MASK_EA)
182 regs->psw.mask |= PSW_MASK_BA;
183 regs->psw.addr = user_sregs.regs.psw.addr;
184 memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
185 memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
186 sizeof(current->thread.acrs));
187
188 memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
189 sizeof(current->thread.fp_regs));
190
191 clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
192 return 0;
193 }
194
195 /* Returns non-zero on fault. */
196 static int save_sigregs_ext(struct pt_regs *regs,
197 _sigregs_ext __user *sregs_ext)
198 {
199 __u64 vxrs[__NUM_VXRS_LOW];
200 int i;
201
202 /* Save vector registers to signal stack */
203 if (current->thread.vxrs) {
204 for (i = 0; i < __NUM_VXRS_LOW; i++)
205 vxrs[i] = *((__u64 *)(current->thread.vxrs + i) + 1);
206 if (__copy_to_user(&sregs_ext->vxrs_low, vxrs,
207 sizeof(sregs_ext->vxrs_low)) ||
208 __copy_to_user(&sregs_ext->vxrs_high,
209 current->thread.vxrs + __NUM_VXRS_LOW,
210 sizeof(sregs_ext->vxrs_high)))
211 return -EFAULT;
212 }
213 return 0;
214 }
215
216 static int restore_sigregs_ext(struct pt_regs *regs,
217 _sigregs_ext __user *sregs_ext)
218 {
219 __u64 vxrs[__NUM_VXRS_LOW];
220 int i;
221
222 /* Restore vector registers from signal stack */
223 if (current->thread.vxrs) {
224 if (__copy_from_user(vxrs, &sregs_ext->vxrs_low,
225 sizeof(sregs_ext->vxrs_low)) ||
226 __copy_from_user(current->thread.vxrs + __NUM_VXRS_LOW,
227 &sregs_ext->vxrs_high,
228 sizeof(sregs_ext->vxrs_high)))
229 return -EFAULT;
230 for (i = 0; i < __NUM_VXRS_LOW; i++)
231 *((__u64 *)(current->thread.vxrs + i) + 1) = vxrs[i];
232 }
233 return 0;
234 }
235
236 SYSCALL_DEFINE0(sigreturn)
237 {
238 struct pt_regs *regs = task_pt_regs(current);
239 struct sigframe __user *frame =
240 (struct sigframe __user *) regs->gprs[15];
241 sigset_t set;
242
243 if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
244 goto badframe;
245 set_current_blocked(&set);
246 if (restore_sigregs(regs, &frame->sregs))
247 goto badframe;
248 if (restore_sigregs_ext(regs, &frame->sregs_ext))
249 goto badframe;
250 load_sigregs();
251 return regs->gprs[2];
252 badframe:
253 force_sig(SIGSEGV, current);
254 return 0;
255 }
256
257 SYSCALL_DEFINE0(rt_sigreturn)
258 {
259 struct pt_regs *regs = task_pt_regs(current);
260 struct rt_sigframe __user *frame =
261 (struct rt_sigframe __user *)regs->gprs[15];
262 sigset_t set;
263
264 if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
265 goto badframe;
266 set_current_blocked(&set);
267 if (restore_altstack(&frame->uc.uc_stack))
268 goto badframe;
269 if (restore_sigregs(regs, &frame->uc.uc_mcontext))
270 goto badframe;
271 if (restore_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
272 goto badframe;
273 load_sigregs();
274 return regs->gprs[2];
275 badframe:
276 force_sig(SIGSEGV, current);
277 return 0;
278 }
279
280 /*
281 * Determine which stack to use..
282 */
283 static inline void __user *
284 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
285 {
286 unsigned long sp;
287
288 /* Default to using normal stack */
289 sp = regs->gprs[15];
290
291 /* Overflow on alternate signal stack gives SIGSEGV. */
292 if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
293 return (void __user *) -1UL;
294
295 /* This is the X/Open sanctioned signal stack switching. */
296 if (ka->sa.sa_flags & SA_ONSTACK) {
297 if (! sas_ss_flags(sp))
298 sp = current->sas_ss_sp + current->sas_ss_size;
299 }
300
301 return (void __user *)((sp - frame_size) & -8ul);
302 }
303
304 static int setup_frame(int sig, struct k_sigaction *ka,
305 sigset_t *set, struct pt_regs * regs)
306 {
307 struct sigframe __user *frame;
308 struct sigcontext sc;
309 unsigned long restorer;
310 size_t frame_size;
311
312 /*
313 * gprs_high are only present for a 31-bit task running on
314 * a 64-bit kernel (see compat_signal.c) but the space for
315 * gprs_high need to be allocated if vector registers are
316 * included in the signal frame on a 31-bit system.
317 */
318 frame_size = sizeof(*frame) - sizeof(frame->sregs_ext);
319 if (MACHINE_HAS_VX)
320 frame_size += sizeof(frame->sregs_ext);
321 frame = get_sigframe(ka, regs, frame_size);
322 if (frame == (void __user *) -1UL)
323 return -EFAULT;
324
325 /* Set up backchain. */
326 if (__put_user(regs->gprs[15], (addr_t __user *) frame))
327 return -EFAULT;
328
329 /* Create struct sigcontext on the signal stack */
330 memcpy(&sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE);
331 sc.sregs = (_sigregs __user __force *) &frame->sregs;
332 if (__copy_to_user(&frame->sc, &sc, sizeof(frame->sc)))
333 return -EFAULT;
334
335 /* Store registers needed to create the signal frame */
336 store_sigregs();
337
338 /* Create _sigregs on the signal stack */
339 if (save_sigregs(regs, &frame->sregs))
340 return -EFAULT;
341
342 /* Place signal number on stack to allow backtrace from handler. */
343 if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
344 return -EFAULT;
345
346 /* Create _sigregs_ext on the signal stack */
347 if (save_sigregs_ext(regs, &frame->sregs_ext))
348 return -EFAULT;
349
350 /* Set up to return from userspace. If provided, use a stub
351 already in userspace. */
352 if (ka->sa.sa_flags & SA_RESTORER) {
353 restorer = (unsigned long) ka->sa.sa_restorer | PSW_ADDR_AMODE;
354 } else {
355 /* Signal frame without vector registers are short ! */
356 __u16 __user *svc = (void __user *) frame + frame_size - 2;
357 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc))
358 return -EFAULT;
359 restorer = (unsigned long) svc | PSW_ADDR_AMODE;
360 }
361
362 /* Set up registers for signal handler */
363 regs->gprs[14] = restorer;
364 regs->gprs[15] = (unsigned long) frame;
365 /* Force default amode and default user address space control. */
366 regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
367 (PSW_USER_BITS & PSW_MASK_ASC) |
368 (regs->psw.mask & ~PSW_MASK_ASC);
369 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
370
371 regs->gprs[2] = sig;
372 regs->gprs[3] = (unsigned long) &frame->sc;
373
374 /* We forgot to include these in the sigcontext.
375 To avoid breaking binary compatibility, they are passed as args. */
376 if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
377 sig == SIGTRAP || sig == SIGFPE) {
378 /* set extra registers only for synchronous signals */
379 regs->gprs[4] = regs->int_code & 127;
380 regs->gprs[5] = regs->int_parm_long;
381 regs->gprs[6] = task_thread_info(current)->last_break;
382 }
383 return 0;
384 }
385
386 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
387 struct pt_regs *regs)
388 {
389 struct rt_sigframe __user *frame;
390 unsigned long uc_flags, restorer;
391 size_t frame_size;
392
393 frame_size = sizeof(struct rt_sigframe) - sizeof(_sigregs_ext);
394 /*
395 * gprs_high are only present for a 31-bit task running on
396 * a 64-bit kernel (see compat_signal.c) but the space for
397 * gprs_high need to be allocated if vector registers are
398 * included in the signal frame on a 31-bit system.
399 */
400 uc_flags = 0;
401 if (MACHINE_HAS_VX) {
402 frame_size += sizeof(_sigregs_ext);
403 if (current->thread.vxrs)
404 uc_flags |= UC_VXRS;
405 }
406 frame = get_sigframe(&ksig->ka, regs, frame_size);
407 if (frame == (void __user *) -1UL)
408 return -EFAULT;
409
410 /* Set up backchain. */
411 if (__put_user(regs->gprs[15], (addr_t __user *) frame))
412 return -EFAULT;
413
414 /* Set up to return from userspace. If provided, use a stub
415 already in userspace. */
416 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
417 restorer = (unsigned long)
418 ksig->ka.sa.sa_restorer | PSW_ADDR_AMODE;
419 } else {
420 __u16 __user *svc = &frame->svc_insn;
421 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, svc))
422 return -EFAULT;
423 restorer = (unsigned long) svc | PSW_ADDR_AMODE;
424 }
425
426 /* Create siginfo on the signal stack */
427 if (copy_siginfo_to_user(&frame->info, &ksig->info))
428 return -EFAULT;
429
430 /* Store registers needed to create the signal frame */
431 store_sigregs();
432
433 /* Create ucontext on the signal stack. */
434 if (__put_user(uc_flags, &frame->uc.uc_flags) ||
435 __put_user(NULL, &frame->uc.uc_link) ||
436 __save_altstack(&frame->uc.uc_stack, regs->gprs[15]) ||
437 save_sigregs(regs, &frame->uc.uc_mcontext) ||
438 __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)) ||
439 save_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
440 return -EFAULT;
441
442 /* Set up registers for signal handler */
443 regs->gprs[14] = restorer;
444 regs->gprs[15] = (unsigned long) frame;
445 /* Force default amode and default user address space control. */
446 regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
447 (PSW_USER_BITS & PSW_MASK_ASC) |
448 (regs->psw.mask & ~PSW_MASK_ASC);
449 regs->psw.addr = (unsigned long) ksig->ka.sa.sa_handler | PSW_ADDR_AMODE;
450
451 regs->gprs[2] = ksig->sig;
452 regs->gprs[3] = (unsigned long) &frame->info;
453 regs->gprs[4] = (unsigned long) &frame->uc;
454 regs->gprs[5] = task_thread_info(current)->last_break;
455 return 0;
456 }
457
458 static void handle_signal(struct ksignal *ksig, sigset_t *oldset,
459 struct pt_regs *regs)
460 {
461 int ret;
462
463 /* Set up the stack frame */
464 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
465 ret = setup_rt_frame(ksig, oldset, regs);
466 else
467 ret = setup_frame(ksig->sig, &ksig->ka, oldset, regs);
468
469 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP));
470 }
471
472 /*
473 * Note that 'init' is a special process: it doesn't get signals it doesn't
474 * want to handle. Thus you cannot kill init even with a SIGKILL even by
475 * mistake.
476 *
477 * Note that we go through the signals twice: once to check the signals that
478 * the kernel can handle, and then we build all the user-level signal handling
479 * stack-frames in one go after that.
480 */
481 void do_signal(struct pt_regs *regs)
482 {
483 struct ksignal ksig;
484 sigset_t *oldset = sigmask_to_save();
485
486 /*
487 * Get signal to deliver. When running under ptrace, at this point
488 * the debugger may change all our registers, including the system
489 * call information.
490 */
491 current_thread_info()->system_call =
492 test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;
493
494 if (get_signal(&ksig)) {
495 /* Whee! Actually deliver the signal. */
496 if (current_thread_info()->system_call) {
497 regs->int_code = current_thread_info()->system_call;
498 /* Check for system call restarting. */
499 switch (regs->gprs[2]) {
500 case -ERESTART_RESTARTBLOCK:
501 case -ERESTARTNOHAND:
502 regs->gprs[2] = -EINTR;
503 break;
504 case -ERESTARTSYS:
505 if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
506 regs->gprs[2] = -EINTR;
507 break;
508 }
509 /* fallthrough */
510 case -ERESTARTNOINTR:
511 regs->gprs[2] = regs->orig_gpr2;
512 regs->psw.addr =
513 __rewind_psw(regs->psw,
514 regs->int_code >> 16);
515 break;
516 }
517 }
518 /* No longer in a system call */
519 clear_pt_regs_flag(regs, PIF_SYSCALL);
520
521 if (is_compat_task())
522 handle_signal32(&ksig, oldset, regs);
523 else
524 handle_signal(&ksig, oldset, regs);
525 return;
526 }
527
528 /* No handlers present - check for system call restart */
529 clear_pt_regs_flag(regs, PIF_SYSCALL);
530 if (current_thread_info()->system_call) {
531 regs->int_code = current_thread_info()->system_call;
532 switch (regs->gprs[2]) {
533 case -ERESTART_RESTARTBLOCK:
534 /* Restart with sys_restart_syscall */
535 regs->int_code = __NR_restart_syscall;
536 /* fallthrough */
537 case -ERESTARTNOHAND:
538 case -ERESTARTSYS:
539 case -ERESTARTNOINTR:
540 /* Restart system call with magic TIF bit. */
541 regs->gprs[2] = regs->orig_gpr2;
542 set_pt_regs_flag(regs, PIF_SYSCALL);
543 if (test_thread_flag(TIF_SINGLE_STEP))
544 clear_pt_regs_flag(regs, PIF_PER_TRAP);
545 break;
546 }
547 }
548
549 /*
550 * If there's no signal to deliver, we just put the saved sigmask back.
551 */
552 restore_saved_sigmask();
553 }
554
555 void do_notify_resume(struct pt_regs *regs)
556 {
557 clear_thread_flag(TIF_NOTIFY_RESUME);
558 tracehook_notify_resume(regs);
559 }
Linux with added FPC-III support