xref: /linux/arch/s390/kernel/signal.c (revision 14b42963f64b98ab61fa9723c03d71aa5ef4f862)
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/smp_lock.h>
18 #include <linux/kernel.h>
19 #include <linux/signal.h>
20 #include <linux/errno.h>
21 #include <linux/wait.h>
22 #include <linux/ptrace.h>
23 #include <linux/unistd.h>
24 #include <linux/stddef.h>
25 #include <linux/tty.h>
26 #include <linux/personality.h>
27 #include <linux/binfmts.h>
28 #include <asm/ucontext.h>
29 #include <asm/uaccess.h>
30 #include <asm/lowcore.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(&current->sighand->siglock);
60 	current->saved_sigmask = current->blocked;
61 	siginitset(&current->blocked, mask);
62 	recalc_sigpending();
63 	spin_unlock_irq(&current->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 			return -EFAULT;
85 		__get_user(new_ka.sa.sa_flags, &act->sa_flags);
86 		__get_user(mask, &act->sa_mask);
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 			return -EFAULT;
97 		__put_user(old_ka.sa.sa_flags, &oact->sa_flags);
98 		__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
99 	}
100 
101 	return ret;
102 }
103 
104 asmlinkage long
105 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
106 					struct pt_regs *regs)
107 {
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 	unsigned long old_mask = regs->psw.mask;
117 	int err;
118 
119 	save_access_regs(current->thread.acrs);
120 
121 	/* Copy a 'clean' PSW mask to the user to avoid leaking
122 	   information about whether PER is currently on.  */
123 	regs->psw.mask = PSW_MASK_MERGE(PSW_USER_BITS, regs->psw.mask);
124 	err = __copy_to_user(&sregs->regs.psw, &regs->psw,
125 			     sizeof(sregs->regs.psw)+sizeof(sregs->regs.gprs));
126 	regs->psw.mask = old_mask;
127 	if (err != 0)
128 		return err;
129 	err = __copy_to_user(&sregs->regs.acrs, current->thread.acrs,
130 			     sizeof(sregs->regs.acrs));
131 	if (err != 0)
132 		return err;
133 	/*
134 	 * We have to store the fp registers to current->thread.fp_regs
135 	 * to merge them with the emulated registers.
136 	 */
137 	save_fp_regs(&current->thread.fp_regs);
138 	return __copy_to_user(&sregs->fpregs, &current->thread.fp_regs,
139 			      sizeof(s390_fp_regs));
140 }
141 
142 /* Returns positive number on error */
143 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
144 {
145 	unsigned long old_mask = regs->psw.mask;
146 	int err;
147 
148 	/* Alwys make any pending restarted system call return -EINTR */
149 	current_thread_info()->restart_block.fn = do_no_restart_syscall;
150 
151 	err = __copy_from_user(&regs->psw, &sregs->regs.psw,
152 			       sizeof(sregs->regs.psw)+sizeof(sregs->regs.gprs));
153 	regs->psw.mask = PSW_MASK_MERGE(old_mask, regs->psw.mask);
154 	regs->psw.addr |= PSW_ADDR_AMODE;
155 	if (err)
156 		return err;
157 	err = __copy_from_user(&current->thread.acrs, &sregs->regs.acrs,
158 			       sizeof(sregs->regs.acrs));
159 	if (err)
160 		return err;
161 	restore_access_regs(current->thread.acrs);
162 
163 	err = __copy_from_user(&current->thread.fp_regs, &sregs->fpregs,
164 			       sizeof(s390_fp_regs));
165 	current->thread.fp_regs.fpc &= FPC_VALID_MASK;
166 	if (err)
167 		return err;
168 
169 	restore_fp_regs(&current->thread.fp_regs);
170 	regs->trap = -1;	/* disable syscall checks */
171 	return 0;
172 }
173 
174 asmlinkage long sys_sigreturn(struct pt_regs *regs)
175 {
176 	sigframe __user *frame = (sigframe __user *)regs->gprs[15];
177 	sigset_t set;
178 
179 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
180 		goto badframe;
181 	if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
182 		goto badframe;
183 
184 	sigdelsetmask(&set, ~_BLOCKABLE);
185 	spin_lock_irq(&current->sighand->siglock);
186 	current->blocked = set;
187 	recalc_sigpending();
188 	spin_unlock_irq(&current->sighand->siglock);
189 
190 	if (restore_sigregs(regs, &frame->sregs))
191 		goto badframe;
192 
193 	return regs->gprs[2];
194 
195 badframe:
196 	force_sig(SIGSEGV, current);
197 	return 0;
198 }
199 
200 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
201 {
202 	rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
203 	sigset_t set;
204 
205 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
206 		goto badframe;
207 	if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
208 		goto badframe;
209 
210 	sigdelsetmask(&set, ~_BLOCKABLE);
211 	spin_lock_irq(&current->sighand->siglock);
212 	current->blocked = set;
213 	recalc_sigpending();
214 	spin_unlock_irq(&current->sighand->siglock);
215 
216 	if (restore_sigregs(regs, &frame->uc.uc_mcontext))
217 		goto badframe;
218 
219 	if (do_sigaltstack(&frame->uc.uc_stack, NULL,
220 			   regs->gprs[15]) == -EFAULT)
221 		goto badframe;
222 	return regs->gprs[2];
223 
224 badframe:
225 	force_sig(SIGSEGV, current);
226 	return 0;
227 }
228 
229 /*
230  * Set up a signal frame.
231  */
232 
233 
234 /*
235  * Determine which stack to use..
236  */
237 static inline void __user *
238 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
239 {
240 	unsigned long sp;
241 
242 	/* Default to using normal stack */
243 	sp = regs->gprs[15];
244 
245 	/* This is the X/Open sanctioned signal stack switching.  */
246 	if (ka->sa.sa_flags & SA_ONSTACK) {
247 		if (! sas_ss_flags(sp))
248 			sp = current->sas_ss_sp + current->sas_ss_size;
249 	}
250 
251 	/* This is the legacy signal stack switching. */
252 	else if (!user_mode(regs) &&
253 		 !(ka->sa.sa_flags & SA_RESTORER) &&
254 		 ka->sa.sa_restorer) {
255 		sp = (unsigned long) ka->sa.sa_restorer;
256 	}
257 
258 	return (void __user *)((sp - frame_size) & -8ul);
259 }
260 
261 static inline int map_signal(int sig)
262 {
263 	if (current_thread_info()->exec_domain
264 	    && current_thread_info()->exec_domain->signal_invmap
265 	    && sig < 32)
266 		return current_thread_info()->exec_domain->signal_invmap[sig];
267 	else
268 		return sig;
269 }
270 
271 static int setup_frame(int sig, struct k_sigaction *ka,
272 		       sigset_t *set, struct pt_regs * regs)
273 {
274 	sigframe __user *frame;
275 
276 	frame = get_sigframe(ka, regs, sizeof(sigframe));
277 	if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
278 		goto give_sigsegv;
279 
280 	if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
281 		goto give_sigsegv;
282 
283 	if (save_sigregs(regs, &frame->sregs))
284 		goto give_sigsegv;
285 	if (__put_user(&frame->sregs, &frame->sc.sregs))
286 		goto give_sigsegv;
287 
288 	/* Set up to return from userspace.  If provided, use a stub
289 	   already in userspace.  */
290 	if (ka->sa.sa_flags & SA_RESTORER) {
291                 regs->gprs[14] = (unsigned long)
292 			ka->sa.sa_restorer | PSW_ADDR_AMODE;
293 	} else {
294                 regs->gprs[14] = (unsigned long)
295 			frame->retcode | PSW_ADDR_AMODE;
296 		if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
297 	                       (u16 __user *)(frame->retcode)))
298 			goto give_sigsegv;
299 	}
300 
301 	/* Set up backchain. */
302 	if (__put_user(regs->gprs[15], (addr_t __user *) frame))
303 		goto give_sigsegv;
304 
305 	/* Set up registers for signal handler */
306 	regs->gprs[15] = (unsigned long) frame;
307 	regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
308 
309 	regs->gprs[2] = map_signal(sig);
310 	regs->gprs[3] = (unsigned long) &frame->sc;
311 
312 	/* We forgot to include these in the sigcontext.
313 	   To avoid breaking binary compatibility, they are passed as args. */
314 	regs->gprs[4] = current->thread.trap_no;
315 	regs->gprs[5] = current->thread.prot_addr;
316 
317 	/* Place signal number on stack to allow backtrace from handler.  */
318 	if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
319 		goto give_sigsegv;
320 	return 0;
321 
322 give_sigsegv:
323 	force_sigsegv(sig, current);
324 	return -EFAULT;
325 }
326 
327 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
328 			   sigset_t *set, struct pt_regs * regs)
329 {
330 	int err = 0;
331 	rt_sigframe __user *frame;
332 
333 	frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
334 	if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
335 		goto give_sigsegv;
336 
337 	if (copy_siginfo_to_user(&frame->info, info))
338 		goto give_sigsegv;
339 
340 	/* Create the ucontext.  */
341 	err |= __put_user(0, &frame->uc.uc_flags);
342 	err |= __put_user(NULL, &frame->uc.uc_link);
343 	err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
344 	err |= __put_user(sas_ss_flags(regs->gprs[15]),
345 			  &frame->uc.uc_stack.ss_flags);
346 	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
347 	err |= save_sigregs(regs, &frame->uc.uc_mcontext);
348 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
349 	if (err)
350 		goto give_sigsegv;
351 
352 	/* Set up to return from userspace.  If provided, use a stub
353 	   already in userspace.  */
354 	if (ka->sa.sa_flags & SA_RESTORER) {
355                 regs->gprs[14] = (unsigned long)
356 			ka->sa.sa_restorer | PSW_ADDR_AMODE;
357 	} else {
358                 regs->gprs[14] = (unsigned long)
359 			frame->retcode | PSW_ADDR_AMODE;
360 		if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
361 			       (u16 __user *)(frame->retcode)))
362 			goto give_sigsegv;
363 	}
364 
365 	/* Set up backchain. */
366 	if (__put_user(regs->gprs[15], (addr_t __user *) frame))
367 		goto give_sigsegv;
368 
369 	/* Set up registers for signal handler */
370 	regs->gprs[15] = (unsigned long) frame;
371 	regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
372 
373 	regs->gprs[2] = map_signal(sig);
374 	regs->gprs[3] = (unsigned long) &frame->info;
375 	regs->gprs[4] = (unsigned long) &frame->uc;
376 	return 0;
377 
378 give_sigsegv:
379 	force_sigsegv(sig, current);
380 	return -EFAULT;
381 }
382 
383 /*
384  * OK, we're invoking a handler
385  */
386 
387 static int
388 handle_signal(unsigned long sig, struct k_sigaction *ka,
389 	      siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
390 {
391 	int ret;
392 
393 	/* Set up the stack frame */
394 	if (ka->sa.sa_flags & SA_SIGINFO)
395 		ret = setup_rt_frame(sig, ka, info, oldset, regs);
396 	else
397 		ret = setup_frame(sig, ka, oldset, regs);
398 
399 	if (ret == 0) {
400 		spin_lock_irq(&current->sighand->siglock);
401 		sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
402 		if (!(ka->sa.sa_flags & SA_NODEFER))
403 			sigaddset(&current->blocked,sig);
404 		recalc_sigpending();
405 		spin_unlock_irq(&current->sighand->siglock);
406 	}
407 
408 	return ret;
409 }
410 
411 /*
412  * Note that 'init' is a special process: it doesn't get signals it doesn't
413  * want to handle. Thus you cannot kill init even with a SIGKILL even by
414  * mistake.
415  *
416  * Note that we go through the signals twice: once to check the signals that
417  * the kernel can handle, and then we build all the user-level signal handling
418  * stack-frames in one go after that.
419  */
420 void do_signal(struct pt_regs *regs)
421 {
422 	unsigned long retval = 0, continue_addr = 0, restart_addr = 0;
423 	siginfo_t info;
424 	int signr;
425 	struct k_sigaction ka;
426 	sigset_t *oldset;
427 
428 	/*
429 	 * We want the common case to go fast, which
430 	 * is why we may in certain cases get here from
431 	 * kernel mode. Just return without doing anything
432 	 * if so.
433 	 */
434 	if (!user_mode(regs))
435 		return;
436 
437 	if (test_thread_flag(TIF_RESTORE_SIGMASK))
438 		oldset = &current->saved_sigmask;
439 	else
440 		oldset = &current->blocked;
441 
442 	/* Are we from a system call? */
443 	if (regs->trap == __LC_SVC_OLD_PSW) {
444 		continue_addr = regs->psw.addr;
445 		restart_addr = continue_addr - regs->ilc;
446 		retval = regs->gprs[2];
447 
448 		/* Prepare for system call restart.  We do this here so that a
449 		   debugger will see the already changed PSW. */
450 		switch (retval) {
451 		case -ERESTARTNOHAND:
452 		case -ERESTARTSYS:
453 		case -ERESTARTNOINTR:
454 			regs->gprs[2] = regs->orig_gpr2;
455 			regs->psw.addr = restart_addr;
456 			break;
457 		case -ERESTART_RESTARTBLOCK:
458 			regs->gprs[2] = -EINTR;
459 		}
460 	}
461 
462 	/* Get signal to deliver.  When running under ptrace, at this point
463 	   the debugger may change all our registers ... */
464 	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
465 
466 	/* Depending on the signal settings we may need to revert the
467 	   decision to restart the system call. */
468 	if (signr > 0 && regs->psw.addr == restart_addr) {
469 		if (retval == -ERESTARTNOHAND
470 		    || (retval == -ERESTARTSYS
471 			 && !(current->sighand->action[signr-1].sa.sa_flags
472 			      & SA_RESTART))) {
473 			regs->gprs[2] = -EINTR;
474 			regs->psw.addr = continue_addr;
475 		}
476 	}
477 
478 	if (signr > 0) {
479 		/* Whee!  Actually deliver the signal.  */
480 #ifdef CONFIG_COMPAT
481 		if (test_thread_flag(TIF_31BIT)) {
482 			extern int handle_signal32(unsigned long sig,
483 						   struct k_sigaction *ka,
484 						   siginfo_t *info,
485 						   sigset_t *oldset,
486 						   struct pt_regs *regs);
487 			if (handle_signal32(
488 				    signr, &ka, &info, oldset, regs) == 0) {
489 				if (test_thread_flag(TIF_RESTORE_SIGMASK))
490 					clear_thread_flag(TIF_RESTORE_SIGMASK);
491 			}
492 			return;
493 	        }
494 #endif
495 		if (handle_signal(signr, &ka, &info, oldset, regs) == 0) {
496 			/*
497 			 * A signal was successfully delivered; the saved
498 			 * sigmask will have been stored in the signal frame,
499 			 * and will be restored by sigreturn, so we can simply
500 			 * clear the TIF_RESTORE_SIGMASK flag.
501 			 */
502 			if (test_thread_flag(TIF_RESTORE_SIGMASK))
503 				clear_thread_flag(TIF_RESTORE_SIGMASK);
504 		}
505 		return;
506 	}
507 
508 	/*
509 	 * If there's no signal to deliver, we just put the saved sigmask back.
510 	 */
511 	if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
512 		clear_thread_flag(TIF_RESTORE_SIGMASK);
513 		sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
514 	}
515 
516 	/* Restart a different system call. */
517 	if (retval == -ERESTART_RESTARTBLOCK
518 	    && regs->psw.addr == continue_addr) {
519 		regs->gprs[2] = __NR_restart_syscall;
520 		set_thread_flag(TIF_RESTART_SVC);
521 	}
522 }
523