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1 | /* | |
2 | * arch/s390/kernel/signal.c | |
3 | * | |
4 | * Copyright (C) IBM Corp. 1999,2006 | |
5 | * Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com) | |
6 | * | |
7 | * Based on Intel version | |
8 | * | |
9 | * Copyright (C) 1991, 1992 Linus Torvalds | |
10 | * | |
11 | * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson | |
12 | */ | |
13 | ||
14 | #include <linux/sched.h> | |
15 | #include <linux/mm.h> | |
16 | #include <linux/smp.h> | |
17 | #include <linux/kernel.h> | |
18 | #include <linux/signal.h> | |
19 | #include <linux/errno.h> | |
20 | #include <linux/wait.h> | |
21 | #include <linux/ptrace.h> | |
22 | #include <linux/unistd.h> | |
23 | #include <linux/stddef.h> | |
24 | #include <linux/tty.h> | |
25 | #include <linux/personality.h> | |
26 | #include <linux/binfmts.h> | |
27 | #include <asm/ucontext.h> | |
28 | #include <asm/uaccess.h> | |
29 | #include <asm/lowcore.h> | |
30 | #include "entry.h" | |
31 | ||
32 | #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) | |
33 | ||
34 | ||
35 | typedef struct | |
36 | { | |
37 | __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; | |
38 | struct sigcontext sc; | |
39 | _sigregs sregs; | |
40 | int signo; | |
41 | __u8 retcode[S390_SYSCALL_SIZE]; | |
42 | } sigframe; | |
43 | ||
44 | typedef struct | |
45 | { | |
46 | __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; | |
47 | __u8 retcode[S390_SYSCALL_SIZE]; | |
48 | struct siginfo info; | |
49 | struct ucontext uc; | |
50 | } rt_sigframe; | |
51 | ||
52 | /* | |
53 | * Atomically swap in the new signal mask, and wait for a signal. | |
54 | */ | |
55 | asmlinkage int | |
56 | sys_sigsuspend(int history0, int history1, old_sigset_t mask) | |
57 | { | |
58 | mask &= _BLOCKABLE; | |
59 | spin_lock_irq(¤t->sighand->siglock); | |
60 | current->saved_sigmask = current->blocked; | |
61 | siginitset(¤t->blocked, mask); | |
62 | recalc_sigpending(); | |
63 | spin_unlock_irq(¤t->sighand->siglock); | |
64 | ||
65 | current->state = TASK_INTERRUPTIBLE; | |
66 | schedule(); | |
67 | set_thread_flag(TIF_RESTORE_SIGMASK); | |
68 | ||
69 | return -ERESTARTNOHAND; | |
70 | } | |
71 | ||
72 | asmlinkage long | |
73 | sys_sigaction(int sig, const struct old_sigaction __user *act, | |
74 | struct old_sigaction __user *oact) | |
75 | { | |
76 | struct k_sigaction new_ka, old_ka; | |
77 | int ret; | |
78 | ||
79 | if (act) { | |
80 | old_sigset_t mask; | |
81 | if (!access_ok(VERIFY_READ, act, sizeof(*act)) || | |
82 | __get_user(new_ka.sa.sa_handler, &act->sa_handler) || | |
83 | __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) || | |
84 | __get_user(new_ka.sa.sa_flags, &act->sa_flags) || | |
85 | __get_user(mask, &act->sa_mask)) | |
86 | return -EFAULT; | |
87 | siginitset(&new_ka.sa.sa_mask, mask); | |
88 | } | |
89 | ||
90 | ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); | |
91 | ||
92 | if (!ret && oact) { | |
93 | if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || | |
94 | __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || | |
95 | __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) || | |
96 | __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || | |
97 | __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) | |
98 | return -EFAULT; | |
99 | } | |
100 | ||
101 | return ret; | |
102 | } | |
103 | ||
104 | asmlinkage long | |
105 | sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss) | |
106 | { | |
107 | struct pt_regs *regs = task_pt_regs(current); | |
108 | return do_sigaltstack(uss, uoss, regs->gprs[15]); | |
109 | } | |
110 | ||
111 | ||
112 | ||
113 | /* Returns non-zero on fault. */ | |
114 | static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs) | |
115 | { | |
116 | _sigregs user_sregs; | |
117 | ||
118 | save_access_regs(current->thread.acrs); | |
119 | ||
120 | /* Copy a 'clean' PSW mask to the user to avoid leaking | |
121 | information about whether PER is currently on. */ | |
122 | user_sregs.regs.psw.mask = PSW_MASK_MERGE(psw_user_bits, regs->psw.mask); | |
123 | user_sregs.regs.psw.addr = regs->psw.addr; | |
124 | memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs)); | |
125 | memcpy(&user_sregs.regs.acrs, current->thread.acrs, | |
126 | sizeof(sregs->regs.acrs)); | |
127 | /* | |
128 | * We have to store the fp registers to current->thread.fp_regs | |
129 | * to merge them with the emulated registers. | |
130 | */ | |
131 | save_fp_regs(¤t->thread.fp_regs); | |
132 | memcpy(&user_sregs.fpregs, ¤t->thread.fp_regs, | |
133 | sizeof(s390_fp_regs)); | |
134 | return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs)); | |
135 | } | |
136 | ||
137 | /* Returns positive number on error */ | |
138 | static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) | |
139 | { | |
140 | int err; | |
141 | _sigregs user_sregs; | |
142 | ||
143 | /* Alwys make any pending restarted system call return -EINTR */ | |
144 | current_thread_info()->restart_block.fn = do_no_restart_syscall; | |
145 | ||
146 | err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs)); | |
147 | if (err) | |
148 | return err; | |
149 | regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask, | |
150 | user_sregs.regs.psw.mask); | |
151 | regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr; | |
152 | memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs)); | |
153 | memcpy(¤t->thread.acrs, &user_sregs.regs.acrs, | |
154 | sizeof(sregs->regs.acrs)); | |
155 | restore_access_regs(current->thread.acrs); | |
156 | ||
157 | memcpy(¤t->thread.fp_regs, &user_sregs.fpregs, | |
158 | sizeof(s390_fp_regs)); | |
159 | current->thread.fp_regs.fpc &= FPC_VALID_MASK; | |
160 | ||
161 | restore_fp_regs(¤t->thread.fp_regs); | |
162 | regs->trap = -1; /* disable syscall checks */ | |
163 | return 0; | |
164 | } | |
165 | ||
166 | asmlinkage long sys_sigreturn(void) | |
167 | { | |
168 | struct pt_regs *regs = task_pt_regs(current); | |
169 | sigframe __user *frame = (sigframe __user *)regs->gprs[15]; | |
170 | sigset_t set; | |
171 | ||
172 | if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) | |
173 | goto badframe; | |
174 | if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE)) | |
175 | goto badframe; | |
176 | ||
177 | sigdelsetmask(&set, ~_BLOCKABLE); | |
178 | spin_lock_irq(¤t->sighand->siglock); | |
179 | current->blocked = set; | |
180 | recalc_sigpending(); | |
181 | spin_unlock_irq(¤t->sighand->siglock); | |
182 | ||
183 | if (restore_sigregs(regs, &frame->sregs)) | |
184 | goto badframe; | |
185 | ||
186 | return regs->gprs[2]; | |
187 | ||
188 | badframe: | |
189 | force_sig(SIGSEGV, current); | |
190 | return 0; | |
191 | } | |
192 | ||
193 | asmlinkage long sys_rt_sigreturn(void) | |
194 | { | |
195 | struct pt_regs *regs = task_pt_regs(current); | |
196 | rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15]; | |
197 | sigset_t set; | |
198 | ||
199 | if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) | |
200 | goto badframe; | |
201 | if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set))) | |
202 | goto badframe; | |
203 | ||
204 | sigdelsetmask(&set, ~_BLOCKABLE); | |
205 | spin_lock_irq(¤t->sighand->siglock); | |
206 | current->blocked = set; | |
207 | recalc_sigpending(); | |
208 | spin_unlock_irq(¤t->sighand->siglock); | |
209 | ||
210 | if (restore_sigregs(regs, &frame->uc.uc_mcontext)) | |
211 | goto badframe; | |
212 | ||
213 | if (do_sigaltstack(&frame->uc.uc_stack, NULL, | |
214 | regs->gprs[15]) == -EFAULT) | |
215 | goto badframe; | |
216 | return regs->gprs[2]; | |
217 | ||
218 | badframe: | |
219 | force_sig(SIGSEGV, current); | |
220 | return 0; | |
221 | } | |
222 | ||
223 | /* | |
224 | * Set up a signal frame. | |
225 | */ | |
226 | ||
227 | ||
228 | /* | |
229 | * Determine which stack to use.. | |
230 | */ | |
231 | static inline void __user * | |
232 | get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) | |
233 | { | |
234 | unsigned long sp; | |
235 | ||
236 | /* Default to using normal stack */ | |
237 | sp = regs->gprs[15]; | |
238 | ||
239 | /* Overflow on alternate signal stack gives SIGSEGV. */ | |
240 | if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL)) | |
241 | return (void __user *) -1UL; | |
242 | ||
243 | /* This is the X/Open sanctioned signal stack switching. */ | |
244 | if (ka->sa.sa_flags & SA_ONSTACK) { | |
245 | if (! sas_ss_flags(sp)) | |
246 | sp = current->sas_ss_sp + current->sas_ss_size; | |
247 | } | |
248 | ||
249 | /* This is the legacy signal stack switching. */ | |
250 | else if (!user_mode(regs) && | |
251 | !(ka->sa.sa_flags & SA_RESTORER) && | |
252 | ka->sa.sa_restorer) { | |
253 | sp = (unsigned long) ka->sa.sa_restorer; | |
254 | } | |
255 | ||
256 | return (void __user *)((sp - frame_size) & -8ul); | |
257 | } | |
258 | ||
259 | static inline int map_signal(int sig) | |
260 | { | |
261 | if (current_thread_info()->exec_domain | |
262 | && current_thread_info()->exec_domain->signal_invmap | |
263 | && sig < 32) | |
264 | return current_thread_info()->exec_domain->signal_invmap[sig]; | |
265 | else | |
266 | return sig; | |
267 | } | |
268 | ||
269 | static int setup_frame(int sig, struct k_sigaction *ka, | |
270 | sigset_t *set, struct pt_regs * regs) | |
271 | { | |
272 | sigframe __user *frame; | |
273 | ||
274 | frame = get_sigframe(ka, regs, sizeof(sigframe)); | |
275 | if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe))) | |
276 | goto give_sigsegv; | |
277 | ||
278 | if (frame == (void __user *) -1UL) | |
279 | goto give_sigsegv; | |
280 | ||
281 | if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE)) | |
282 | goto give_sigsegv; | |
283 | ||
284 | if (save_sigregs(regs, &frame->sregs)) | |
285 | goto give_sigsegv; | |
286 | if (__put_user(&frame->sregs, &frame->sc.sregs)) | |
287 | goto give_sigsegv; | |
288 | ||
289 | /* Set up to return from userspace. If provided, use a stub | |
290 | already in userspace. */ | |
291 | if (ka->sa.sa_flags & SA_RESTORER) { | |
292 | regs->gprs[14] = (unsigned long) | |
293 | ka->sa.sa_restorer | PSW_ADDR_AMODE; | |
294 | } else { | |
295 | regs->gprs[14] = (unsigned long) | |
296 | frame->retcode | PSW_ADDR_AMODE; | |
297 | if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, | |
298 | (u16 __user *)(frame->retcode))) | |
299 | goto give_sigsegv; | |
300 | } | |
301 | ||
302 | /* Set up backchain. */ | |
303 | if (__put_user(regs->gprs[15], (addr_t __user *) frame)) | |
304 | goto give_sigsegv; | |
305 | ||
306 | /* Set up registers for signal handler */ | |
307 | regs->gprs[15] = (unsigned long) frame; | |
308 | regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; | |
309 | ||
310 | regs->gprs[2] = map_signal(sig); | |
311 | regs->gprs[3] = (unsigned long) &frame->sc; | |
312 | ||
313 | /* We forgot to include these in the sigcontext. | |
314 | To avoid breaking binary compatibility, they are passed as args. */ | |
315 | regs->gprs[4] = current->thread.trap_no; | |
316 | regs->gprs[5] = current->thread.prot_addr; | |
317 | ||
318 | /* Place signal number on stack to allow backtrace from handler. */ | |
319 | if (__put_user(regs->gprs[2], (int __user *) &frame->signo)) | |
320 | goto give_sigsegv; | |
321 | return 0; | |
322 | ||
323 | give_sigsegv: | |
324 | force_sigsegv(sig, current); | |
325 | return -EFAULT; | |
326 | } | |
327 | ||
328 | static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, | |
329 | sigset_t *set, struct pt_regs * regs) | |
330 | { | |
331 | int err = 0; | |
332 | rt_sigframe __user *frame; | |
333 | ||
334 | frame = get_sigframe(ka, regs, sizeof(rt_sigframe)); | |
335 | if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe))) | |
336 | goto give_sigsegv; | |
337 | ||
338 | if (frame == (void __user *) -1UL) | |
339 | goto give_sigsegv; | |
340 | ||
341 | if (copy_siginfo_to_user(&frame->info, info)) | |
342 | goto give_sigsegv; | |
343 | ||
344 | /* Create the ucontext. */ | |
345 | err |= __put_user(0, &frame->uc.uc_flags); | |
346 | err |= __put_user(NULL, &frame->uc.uc_link); | |
347 | err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); | |
348 | err |= __put_user(sas_ss_flags(regs->gprs[15]), | |
349 | &frame->uc.uc_stack.ss_flags); | |
350 | err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); | |
351 | err |= save_sigregs(regs, &frame->uc.uc_mcontext); | |
352 | err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); | |
353 | if (err) | |
354 | goto give_sigsegv; | |
355 | ||
356 | /* Set up to return from userspace. If provided, use a stub | |
357 | already in userspace. */ | |
358 | if (ka->sa.sa_flags & SA_RESTORER) { | |
359 | regs->gprs[14] = (unsigned long) | |
360 | ka->sa.sa_restorer | PSW_ADDR_AMODE; | |
361 | } else { | |
362 | regs->gprs[14] = (unsigned long) | |
363 | frame->retcode | PSW_ADDR_AMODE; | |
364 | if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, | |
365 | (u16 __user *)(frame->retcode))) | |
366 | goto give_sigsegv; | |
367 | } | |
368 | ||
369 | /* Set up backchain. */ | |
370 | if (__put_user(regs->gprs[15], (addr_t __user *) frame)) | |
371 | goto give_sigsegv; | |
372 | ||
373 | /* Set up registers for signal handler */ | |
374 | regs->gprs[15] = (unsigned long) frame; | |
375 | regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; | |
376 | ||
377 | regs->gprs[2] = map_signal(sig); | |
378 | regs->gprs[3] = (unsigned long) &frame->info; | |
379 | regs->gprs[4] = (unsigned long) &frame->uc; | |
380 | return 0; | |
381 | ||
382 | give_sigsegv: | |
383 | force_sigsegv(sig, current); | |
384 | return -EFAULT; | |
385 | } | |
386 | ||
387 | /* | |
388 | * OK, we're invoking a handler | |
389 | */ | |
390 | ||
391 | static int | |
392 | handle_signal(unsigned long sig, struct k_sigaction *ka, | |
393 | siginfo_t *info, sigset_t *oldset, struct pt_regs * regs) | |
394 | { | |
395 | int ret; | |
396 | ||
397 | /* Set up the stack frame */ | |
398 | if (ka->sa.sa_flags & SA_SIGINFO) | |
399 | ret = setup_rt_frame(sig, ka, info, oldset, regs); | |
400 | else | |
401 | ret = setup_frame(sig, ka, oldset, regs); | |
402 | ||
403 | if (ret == 0) { | |
404 | spin_lock_irq(¤t->sighand->siglock); | |
405 | sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask); | |
406 | if (!(ka->sa.sa_flags & SA_NODEFER)) | |
407 | sigaddset(¤t->blocked,sig); | |
408 | recalc_sigpending(); | |
409 | spin_unlock_irq(¤t->sighand->siglock); | |
410 | } | |
411 | ||
412 | return ret; | |
413 | } | |
414 | ||
415 | /* | |
416 | * Note that 'init' is a special process: it doesn't get signals it doesn't | |
417 | * want to handle. Thus you cannot kill init even with a SIGKILL even by | |
418 | * mistake. | |
419 | * | |
420 | * Note that we go through the signals twice: once to check the signals that | |
421 | * the kernel can handle, and then we build all the user-level signal handling | |
422 | * stack-frames in one go after that. | |
423 | */ | |
424 | void do_signal(struct pt_regs *regs) | |
425 | { | |
426 | unsigned long retval = 0, continue_addr = 0, restart_addr = 0; | |
427 | siginfo_t info; | |
428 | int signr; | |
429 | struct k_sigaction ka; | |
430 | sigset_t *oldset; | |
431 | ||
432 | /* | |
433 | * We want the common case to go fast, which | |
434 | * is why we may in certain cases get here from | |
435 | * kernel mode. Just return without doing anything | |
436 | * if so. | |
437 | */ | |
438 | if (!user_mode(regs)) | |
439 | return; | |
440 | ||
441 | if (test_thread_flag(TIF_RESTORE_SIGMASK)) | |
442 | oldset = ¤t->saved_sigmask; | |
443 | else | |
444 | oldset = ¤t->blocked; | |
445 | ||
446 | /* Are we from a system call? */ | |
447 | if (regs->trap == __LC_SVC_OLD_PSW) { | |
448 | continue_addr = regs->psw.addr; | |
449 | restart_addr = continue_addr - regs->ilc; | |
450 | retval = regs->gprs[2]; | |
451 | ||
452 | /* Prepare for system call restart. We do this here so that a | |
453 | debugger will see the already changed PSW. */ | |
454 | switch (retval) { | |
455 | case -ERESTARTNOHAND: | |
456 | case -ERESTARTSYS: | |
457 | case -ERESTARTNOINTR: | |
458 | regs->gprs[2] = regs->orig_gpr2; | |
459 | regs->psw.addr = restart_addr; | |
460 | break; | |
461 | case -ERESTART_RESTARTBLOCK: | |
462 | regs->gprs[2] = -EINTR; | |
463 | } | |
464 | regs->trap = -1; /* Don't deal with this again. */ | |
465 | } | |
466 | ||
467 | /* Get signal to deliver. When running under ptrace, at this point | |
468 | the debugger may change all our registers ... */ | |
469 | signr = get_signal_to_deliver(&info, &ka, regs, NULL); | |
470 | ||
471 | /* Depending on the signal settings we may need to revert the | |
472 | decision to restart the system call. */ | |
473 | if (signr > 0 && regs->psw.addr == restart_addr) { | |
474 | if (retval == -ERESTARTNOHAND | |
475 | || (retval == -ERESTARTSYS | |
476 | && !(current->sighand->action[signr-1].sa.sa_flags | |
477 | & SA_RESTART))) { | |
478 | regs->gprs[2] = -EINTR; | |
479 | regs->psw.addr = continue_addr; | |
480 | } | |
481 | } | |
482 | ||
483 | if (signr > 0) { | |
484 | /* Whee! Actually deliver the signal. */ | |
485 | int ret; | |
486 | #ifdef CONFIG_COMPAT | |
487 | if (test_thread_flag(TIF_31BIT)) { | |
488 | ret = handle_signal32(signr, &ka, &info, oldset, regs); | |
489 | } | |
490 | else | |
491 | #endif | |
492 | ret = handle_signal(signr, &ka, &info, oldset, regs); | |
493 | if (!ret) { | |
494 | /* | |
495 | * A signal was successfully delivered; the saved | |
496 | * sigmask will have been stored in the signal frame, | |
497 | * and will be restored by sigreturn, so we can simply | |
498 | * clear the TIF_RESTORE_SIGMASK flag. | |
499 | */ | |
500 | if (test_thread_flag(TIF_RESTORE_SIGMASK)) | |
501 | clear_thread_flag(TIF_RESTORE_SIGMASK); | |
502 | ||
503 | /* | |
504 | * If we would have taken a single-step trap | |
505 | * for a normal instruction, act like we took | |
506 | * one for the handler setup. | |
507 | */ | |
508 | if (current->thread.per_info.single_step) | |
509 | set_thread_flag(TIF_SINGLE_STEP); | |
510 | } | |
511 | return; | |
512 | } | |
513 | ||
514 | /* | |
515 | * If there's no signal to deliver, we just put the saved sigmask back. | |
516 | */ | |
517 | if (test_thread_flag(TIF_RESTORE_SIGMASK)) { | |
518 | clear_thread_flag(TIF_RESTORE_SIGMASK); | |
519 | sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); | |
520 | } | |
521 | ||
522 | /* Restart a different system call. */ | |
523 | if (retval == -ERESTART_RESTARTBLOCK | |
524 | && regs->psw.addr == continue_addr) { | |
525 | regs->gprs[2] = __NR_restart_syscall; | |
526 | set_thread_flag(TIF_RESTART_SVC); | |
527 | } | |
528 | } |