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 <linux/tracehook.h>
28 #include <linux/syscalls.h>
29 #include <linux/compat.h>
30 #include <asm/ucontext.h>
31 #include <asm/uaccess.h>
32 #include <asm/lowcore.h>
33 #include <asm/switch_to.h>
34 #include "entry.h"
35
36 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
37
38
39 typedef struct
40 {
41 __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
42 struct sigcontext sc;
43 _sigregs sregs;
44 int signo;
45 __u8 retcode[S390_SYSCALL_SIZE];
46 } sigframe;
47
48 typedef struct
49 {
50 __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
51 __u8 retcode[S390_SYSCALL_SIZE];
52 struct siginfo info;
53 struct ucontext uc;
54 } rt_sigframe;
55
56 /*
57 * Atomically swap in the new signal mask, and wait for a signal.
58 */
SYSCALL_DEFINE3(sigsuspend,int,history0,int,history1,old_sigset_t,mask)59 SYSCALL_DEFINE3(sigsuspend, int, history0, int, history1, old_sigset_t, mask)
60 {
61 sigset_t blocked;
62
63 current->saved_sigmask = current->blocked;
64 mask &= _BLOCKABLE;
65 siginitset(&blocked, mask);
66 set_current_blocked(&blocked);
67 set_current_state(TASK_INTERRUPTIBLE);
68 schedule();
69 set_restore_sigmask();
70 return -ERESTARTNOHAND;
71 }
72
SYSCALL_DEFINE3(sigaction,int,sig,const struct old_sigaction __user *,act,struct old_sigaction __user *,oact)73 SYSCALL_DEFINE3(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
SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss,stack_t __user *,uoss)104 SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss,
105 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 /* Returns non-zero on fault. */
save_sigregs(struct pt_regs * regs,_sigregs __user * sregs)112 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
113 {
114 _sigregs user_sregs;
115
116 save_access_regs(current->thread.acrs);
117
118 /* Copy a 'clean' PSW mask to the user to avoid leaking
119 information about whether PER is currently on. */
120 user_sregs.regs.psw.mask = psw_user_bits |
121 (regs->psw.mask & PSW_MASK_USER);
122 user_sregs.regs.psw.addr = regs->psw.addr;
123 memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs));
124 memcpy(&user_sregs.regs.acrs, current->thread.acrs,
125 sizeof(sregs->regs.acrs));
126 /*
127 * We have to store the fp registers to current->thread.fp_regs
128 * to merge them with the emulated registers.
129 */
130 save_fp_regs(¤t->thread.fp_regs);
131 memcpy(&user_sregs.fpregs, ¤t->thread.fp_regs,
132 sizeof(s390_fp_regs));
133 return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs));
134 }
135
136 /* Returns positive number on error */
restore_sigregs(struct pt_regs * regs,_sigregs __user * sregs)137 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
138 {
139 int err;
140 _sigregs user_sregs;
141
142 /* Alwys make any pending restarted system call return -EINTR */
143 current_thread_info()->restart_block.fn = do_no_restart_syscall;
144
145 err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
146 if (err)
147 return err;
148 /* Use regs->psw.mask instead of psw_user_bits to preserve PER bit. */
149 regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
150 (user_sregs.regs.psw.mask & PSW_MASK_USER);
151 /* Check for invalid user address space control. */
152 if ((regs->psw.mask & PSW_MASK_ASC) >= (psw_kernel_bits & PSW_MASK_ASC))
153 regs->psw.mask = (psw_user_bits & PSW_MASK_ASC) |
154 (regs->psw.mask & ~PSW_MASK_ASC);
155 /* Check for invalid amode */
156 if (regs->psw.mask & PSW_MASK_EA)
157 regs->psw.mask |= PSW_MASK_BA;
158 regs->psw.addr = user_sregs.regs.psw.addr;
159 memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
160 memcpy(¤t->thread.acrs, &user_sregs.regs.acrs,
161 sizeof(sregs->regs.acrs));
162 restore_access_regs(current->thread.acrs);
163
164 memcpy(¤t->thread.fp_regs, &user_sregs.fpregs,
165 sizeof(s390_fp_regs));
166 current->thread.fp_regs.fpc &= FPC_VALID_MASK;
167
168 restore_fp_regs(¤t->thread.fp_regs);
169 clear_thread_flag(TIF_SYSCALL); /* No longer in a system call */
170 return 0;
171 }
172
SYSCALL_DEFINE0(sigreturn)173 SYSCALL_DEFINE0(sigreturn)
174 {
175 struct pt_regs *regs = task_pt_regs(current);
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 sigdelsetmask(&set, ~_BLOCKABLE);
184 set_current_blocked(&set);
185 if (restore_sigregs(regs, &frame->sregs))
186 goto badframe;
187 return regs->gprs[2];
188 badframe:
189 force_sig(SIGSEGV, current);
190 return 0;
191 }
192
SYSCALL_DEFINE0(rt_sigreturn)193 SYSCALL_DEFINE0(rt_sigreturn)
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 sigdelsetmask(&set, ~_BLOCKABLE);
204 set_current_blocked(&set);
205 if (restore_sigregs(regs, &frame->uc.uc_mcontext))
206 goto badframe;
207 if (do_sigaltstack(&frame->uc.uc_stack, NULL,
208 regs->gprs[15]) == -EFAULT)
209 goto badframe;
210 return regs->gprs[2];
211 badframe:
212 force_sig(SIGSEGV, current);
213 return 0;
214 }
215
216 /*
217 * Set up a signal frame.
218 */
219
220
221 /*
222 * Determine which stack to use..
223 */
224 static inline void __user *
get_sigframe(struct k_sigaction * ka,struct pt_regs * regs,size_t frame_size)225 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
226 {
227 unsigned long sp;
228
229 /* Default to using normal stack */
230 sp = regs->gprs[15];
231
232 /* Overflow on alternate signal stack gives SIGSEGV. */
233 if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
234 return (void __user *) -1UL;
235
236 /* This is the X/Open sanctioned signal stack switching. */
237 if (ka->sa.sa_flags & SA_ONSTACK) {
238 if (! sas_ss_flags(sp))
239 sp = current->sas_ss_sp + current->sas_ss_size;
240 }
241
242 /* This is the legacy signal stack switching. */
243 else if (!user_mode(regs) &&
244 !(ka->sa.sa_flags & SA_RESTORER) &&
245 ka->sa.sa_restorer) {
246 sp = (unsigned long) ka->sa.sa_restorer;
247 }
248
249 return (void __user *)((sp - frame_size) & -8ul);
250 }
251
map_signal(int sig)252 static inline int map_signal(int sig)
253 {
254 if (current_thread_info()->exec_domain
255 && current_thread_info()->exec_domain->signal_invmap
256 && sig < 32)
257 return current_thread_info()->exec_domain->signal_invmap[sig];
258 else
259 return sig;
260 }
261
setup_frame(int sig,struct k_sigaction * ka,sigset_t * set,struct pt_regs * regs)262 static int setup_frame(int sig, struct k_sigaction *ka,
263 sigset_t *set, struct pt_regs * regs)
264 {
265 sigframe __user *frame;
266
267 frame = get_sigframe(ka, regs, sizeof(sigframe));
268 if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
269 goto give_sigsegv;
270
271 if (frame == (void __user *) -1UL)
272 goto give_sigsegv;
273
274 if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
275 goto give_sigsegv;
276
277 if (save_sigregs(regs, &frame->sregs))
278 goto give_sigsegv;
279 if (__put_user(&frame->sregs, &frame->sc.sregs))
280 goto give_sigsegv;
281
282 /* Set up to return from userspace. If provided, use a stub
283 already in userspace. */
284 if (ka->sa.sa_flags & SA_RESTORER) {
285 regs->gprs[14] = (unsigned long)
286 ka->sa.sa_restorer | PSW_ADDR_AMODE;
287 } else {
288 regs->gprs[14] = (unsigned long)
289 frame->retcode | PSW_ADDR_AMODE;
290 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
291 (u16 __user *)(frame->retcode)))
292 goto give_sigsegv;
293 }
294
295 /* Set up backchain. */
296 if (__put_user(regs->gprs[15], (addr_t __user *) frame))
297 goto give_sigsegv;
298
299 /* Set up registers for signal handler */
300 regs->gprs[15] = (unsigned long) frame;
301 /* Force default amode and default user address space control. */
302 regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
303 (psw_user_bits & PSW_MASK_ASC) |
304 (regs->psw.mask & ~PSW_MASK_ASC);
305 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
306
307 regs->gprs[2] = map_signal(sig);
308 regs->gprs[3] = (unsigned long) &frame->sc;
309
310 /* We forgot to include these in the sigcontext.
311 To avoid breaking binary compatibility, they are passed as args. */
312 if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
313 sig == SIGTRAP || sig == SIGFPE) {
314 /* set extra registers only for synchronous signals */
315 regs->gprs[4] = regs->int_code & 127;
316 regs->gprs[5] = regs->int_parm_long;
317 regs->gprs[6] = task_thread_info(current)->last_break;
318 }
319
320 /* Place signal number on stack to allow backtrace from handler. */
321 if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
322 goto give_sigsegv;
323 return 0;
324
325 give_sigsegv:
326 force_sigsegv(sig, current);
327 return -EFAULT;
328 }
329
setup_rt_frame(int sig,struct k_sigaction * ka,siginfo_t * info,sigset_t * set,struct pt_regs * regs)330 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
331 sigset_t *set, struct pt_regs * regs)
332 {
333 int err = 0;
334 rt_sigframe __user *frame;
335
336 frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
337 if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
338 goto give_sigsegv;
339
340 if (frame == (void __user *) -1UL)
341 goto give_sigsegv;
342
343 if (copy_siginfo_to_user(&frame->info, info))
344 goto give_sigsegv;
345
346 /* Create the ucontext. */
347 err |= __put_user(0, &frame->uc.uc_flags);
348 err |= __put_user(NULL, &frame->uc.uc_link);
349 err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
350 err |= __put_user(sas_ss_flags(regs->gprs[15]),
351 &frame->uc.uc_stack.ss_flags);
352 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
353 err |= save_sigregs(regs, &frame->uc.uc_mcontext);
354 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
355 if (err)
356 goto give_sigsegv;
357
358 /* Set up to return from userspace. If provided, use a stub
359 already in userspace. */
360 if (ka->sa.sa_flags & SA_RESTORER) {
361 regs->gprs[14] = (unsigned long)
362 ka->sa.sa_restorer | PSW_ADDR_AMODE;
363 } else {
364 regs->gprs[14] = (unsigned long)
365 frame->retcode | PSW_ADDR_AMODE;
366 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
367 (u16 __user *)(frame->retcode)))
368 goto give_sigsegv;
369 }
370
371 /* Set up backchain. */
372 if (__put_user(regs->gprs[15], (addr_t __user *) frame))
373 goto give_sigsegv;
374
375 /* Set up registers for signal handler */
376 regs->gprs[15] = (unsigned long) frame;
377 /* Force default amode and default user address space control. */
378 regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
379 (psw_user_bits & PSW_MASK_ASC) |
380 (regs->psw.mask & ~PSW_MASK_ASC);
381 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
382
383 regs->gprs[2] = map_signal(sig);
384 regs->gprs[3] = (unsigned long) &frame->info;
385 regs->gprs[4] = (unsigned long) &frame->uc;
386 regs->gprs[5] = task_thread_info(current)->last_break;
387 return 0;
388
389 give_sigsegv:
390 force_sigsegv(sig, current);
391 return -EFAULT;
392 }
393
handle_signal(unsigned long sig,struct k_sigaction * ka,siginfo_t * info,sigset_t * oldset,struct pt_regs * regs)394 static int handle_signal(unsigned long sig, struct k_sigaction *ka,
395 siginfo_t *info, sigset_t *oldset,
396 struct pt_regs *regs)
397 {
398 int ret;
399
400 /* Set up the stack frame */
401 if (ka->sa.sa_flags & SA_SIGINFO)
402 ret = setup_rt_frame(sig, ka, info, oldset, regs);
403 else
404 ret = setup_frame(sig, ka, oldset, regs);
405 if (ret)
406 return ret;
407 block_sigmask(ka, sig);
408 return 0;
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 */
do_signal(struct pt_regs * regs)420 void do_signal(struct pt_regs *regs)
421 {
422 siginfo_t info;
423 int signr;
424 struct k_sigaction ka;
425 sigset_t *oldset;
426
427 /*
428 * We want the common case to go fast, which
429 * is why we may in certain cases get here from
430 * kernel mode. Just return without doing anything
431 * if so.
432 */
433 if (!user_mode(regs))
434 return;
435
436 if (test_thread_flag(TIF_RESTORE_SIGMASK))
437 oldset = ¤t->saved_sigmask;
438 else
439 oldset = ¤t->blocked;
440
441 /*
442 * Get signal to deliver. When running under ptrace, at this point
443 * the debugger may change all our registers, including the system
444 * call information.
445 */
446 current_thread_info()->system_call =
447 test_thread_flag(TIF_SYSCALL) ? regs->int_code : 0;
448 signr = get_signal_to_deliver(&info, &ka, regs, NULL);
449
450 if (signr > 0) {
451 /* Whee! Actually deliver the signal. */
452 if (current_thread_info()->system_call) {
453 regs->int_code = current_thread_info()->system_call;
454 /* Check for system call restarting. */
455 switch (regs->gprs[2]) {
456 case -ERESTART_RESTARTBLOCK:
457 case -ERESTARTNOHAND:
458 regs->gprs[2] = -EINTR;
459 break;
460 case -ERESTARTSYS:
461 if (!(ka.sa.sa_flags & SA_RESTART)) {
462 regs->gprs[2] = -EINTR;
463 break;
464 }
465 /* fallthrough */
466 case -ERESTARTNOINTR:
467 regs->gprs[2] = regs->orig_gpr2;
468 regs->psw.addr =
469 __rewind_psw(regs->psw,
470 regs->int_code >> 16);
471 break;
472 }
473 }
474 /* No longer in a system call */
475 clear_thread_flag(TIF_SYSCALL);
476
477 if ((is_compat_task() ?
478 handle_signal32(signr, &ka, &info, oldset, regs) :
479 handle_signal(signr, &ka, &info, oldset, regs)) == 0) {
480 /*
481 * A signal was successfully delivered; the saved
482 * sigmask will have been stored in the signal frame,
483 * and will be restored by sigreturn, so we can simply
484 * clear the TIF_RESTORE_SIGMASK flag.
485 */
486 if (test_thread_flag(TIF_RESTORE_SIGMASK))
487 clear_thread_flag(TIF_RESTORE_SIGMASK);
488
489 /*
490 * Let tracing know that we've done the handler setup.
491 */
492 tracehook_signal_handler(signr, &info, &ka, regs,
493 test_thread_flag(TIF_SINGLE_STEP));
494 }
495 return;
496 }
497
498 /* No handlers present - check for system call restart */
499 clear_thread_flag(TIF_SYSCALL);
500 if (current_thread_info()->system_call) {
501 regs->int_code = current_thread_info()->system_call;
502 switch (regs->gprs[2]) {
503 case -ERESTART_RESTARTBLOCK:
504 /* Restart with sys_restart_syscall */
505 regs->int_code = __NR_restart_syscall;
506 /* fallthrough */
507 case -ERESTARTNOHAND:
508 case -ERESTARTSYS:
509 case -ERESTARTNOINTR:
510 /* Restart system call with magic TIF bit. */
511 regs->gprs[2] = regs->orig_gpr2;
512 set_thread_flag(TIF_SYSCALL);
513 break;
514 }
515 }
516
517 /*
518 * If there's no signal to deliver, we just put the saved sigmask back.
519 */
520 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
521 clear_thread_flag(TIF_RESTORE_SIGMASK);
522 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL);
523 }
524 }
525
do_notify_resume(struct pt_regs * regs)526 void do_notify_resume(struct pt_regs *regs)
527 {
528 clear_thread_flag(TIF_NOTIFY_RESUME);
529 tracehook_notify_resume(regs);
530 if (current->replacement_session_keyring)
531 key_replace_session_keyring();
532 }
533