Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
[linux-2.6] / arch / s390 / kernel / signal.c
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                     __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, &regs->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(&current->thread.fp_regs);
132         memcpy(&user_sregs.fpregs, &current->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(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
153         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
154                sizeof(sregs->regs.acrs));
155         restore_access_regs(current->thread.acrs);
156
157         memcpy(&current->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(&current->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(&current->sighand->siglock);
179         current->blocked = set;
180         recalc_sigpending();
181         spin_unlock_irq(&current->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(&current->sighand->siglock);
206         current->blocked = set;
207         recalc_sigpending();
208         spin_unlock_irq(&current->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         /* This is the X/Open sanctioned signal stack switching.  */
240         if (ka->sa.sa_flags & SA_ONSTACK) {
241                 if (! sas_ss_flags(sp))
242                         sp = current->sas_ss_sp + current->sas_ss_size;
243         }
244
245         /* This is the legacy signal stack switching. */
246         else if (!user_mode(regs) &&
247                  !(ka->sa.sa_flags & SA_RESTORER) &&
248                  ka->sa.sa_restorer) {
249                 sp = (unsigned long) ka->sa.sa_restorer;
250         }
251
252         return (void __user *)((sp - frame_size) & -8ul);
253 }
254
255 static inline int map_signal(int sig)
256 {
257         if (current_thread_info()->exec_domain
258             && current_thread_info()->exec_domain->signal_invmap
259             && sig < 32)
260                 return current_thread_info()->exec_domain->signal_invmap[sig];
261         else
262                 return sig;
263 }
264
265 static int setup_frame(int sig, struct k_sigaction *ka,
266                        sigset_t *set, struct pt_regs * regs)
267 {
268         sigframe __user *frame;
269
270         frame = get_sigframe(ka, regs, sizeof(sigframe));
271         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
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         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
302
303         regs->gprs[2] = map_signal(sig);
304         regs->gprs[3] = (unsigned long) &frame->sc;
305
306         /* We forgot to include these in the sigcontext.
307            To avoid breaking binary compatibility, they are passed as args. */
308         regs->gprs[4] = current->thread.trap_no;
309         regs->gprs[5] = current->thread.prot_addr;
310
311         /* Place signal number on stack to allow backtrace from handler.  */
312         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
313                 goto give_sigsegv;
314         return 0;
315
316 give_sigsegv:
317         force_sigsegv(sig, current);
318         return -EFAULT;
319 }
320
321 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
322                            sigset_t *set, struct pt_regs * regs)
323 {
324         int err = 0;
325         rt_sigframe __user *frame;
326
327         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
328         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
329                 goto give_sigsegv;
330
331         if (copy_siginfo_to_user(&frame->info, info))
332                 goto give_sigsegv;
333
334         /* Create the ucontext.  */
335         err |= __put_user(0, &frame->uc.uc_flags);
336         err |= __put_user(NULL, &frame->uc.uc_link);
337         err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
338         err |= __put_user(sas_ss_flags(regs->gprs[15]),
339                           &frame->uc.uc_stack.ss_flags);
340         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
341         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
342         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
343         if (err)
344                 goto give_sigsegv;
345
346         /* Set up to return from userspace.  If provided, use a stub
347            already in userspace.  */
348         if (ka->sa.sa_flags & SA_RESTORER) {
349                 regs->gprs[14] = (unsigned long)
350                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
351         } else {
352                 regs->gprs[14] = (unsigned long)
353                         frame->retcode | PSW_ADDR_AMODE;
354                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
355                                (u16 __user *)(frame->retcode)))
356                         goto give_sigsegv;
357         }
358
359         /* Set up backchain. */
360         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
361                 goto give_sigsegv;
362
363         /* Set up registers for signal handler */
364         regs->gprs[15] = (unsigned long) frame;
365         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
366
367         regs->gprs[2] = map_signal(sig);
368         regs->gprs[3] = (unsigned long) &frame->info;
369         regs->gprs[4] = (unsigned long) &frame->uc;
370         return 0;
371
372 give_sigsegv:
373         force_sigsegv(sig, current);
374         return -EFAULT;
375 }
376
377 /*
378  * OK, we're invoking a handler
379  */     
380
381 static int
382 handle_signal(unsigned long sig, struct k_sigaction *ka,
383               siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
384 {
385         int ret;
386
387         /* Set up the stack frame */
388         if (ka->sa.sa_flags & SA_SIGINFO)
389                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
390         else
391                 ret = setup_frame(sig, ka, oldset, regs);
392
393         if (ret == 0) {
394                 spin_lock_irq(&current->sighand->siglock);
395                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
396                 if (!(ka->sa.sa_flags & SA_NODEFER))
397                         sigaddset(&current->blocked,sig);
398                 recalc_sigpending();
399                 spin_unlock_irq(&current->sighand->siglock);
400         }
401
402         return ret;
403 }
404
405 /*
406  * Note that 'init' is a special process: it doesn't get signals it doesn't
407  * want to handle. Thus you cannot kill init even with a SIGKILL even by
408  * mistake.
409  *
410  * Note that we go through the signals twice: once to check the signals that
411  * the kernel can handle, and then we build all the user-level signal handling
412  * stack-frames in one go after that.
413  */
414 void do_signal(struct pt_regs *regs)
415 {
416         unsigned long retval = 0, continue_addr = 0, restart_addr = 0;
417         siginfo_t info;
418         int signr;
419         struct k_sigaction ka;
420         sigset_t *oldset;
421
422         /*
423          * We want the common case to go fast, which
424          * is why we may in certain cases get here from
425          * kernel mode. Just return without doing anything
426          * if so.
427          */
428         if (!user_mode(regs))
429                 return;
430
431         if (test_thread_flag(TIF_RESTORE_SIGMASK))
432                 oldset = &current->saved_sigmask;
433         else
434                 oldset = &current->blocked;
435
436         /* Are we from a system call? */
437         if (regs->trap == __LC_SVC_OLD_PSW) {
438                 continue_addr = regs->psw.addr;
439                 restart_addr = continue_addr - regs->ilc;
440                 retval = regs->gprs[2];
441
442                 /* Prepare for system call restart.  We do this here so that a
443                    debugger will see the already changed PSW. */
444                 switch (retval) {
445                 case -ERESTARTNOHAND:
446                 case -ERESTARTSYS:
447                 case -ERESTARTNOINTR:
448                         regs->gprs[2] = regs->orig_gpr2;
449                         regs->psw.addr = restart_addr;
450                         break;
451                 case -ERESTART_RESTARTBLOCK:
452                         regs->gprs[2] = -EINTR;
453                 }
454                 regs->trap = -1;        /* Don't deal with this again. */
455         }
456
457         /* Get signal to deliver.  When running under ptrace, at this point
458            the debugger may change all our registers ... */
459         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
460
461         /* Depending on the signal settings we may need to revert the
462            decision to restart the system call. */
463         if (signr > 0 && regs->psw.addr == restart_addr) {
464                 if (retval == -ERESTARTNOHAND
465                     || (retval == -ERESTARTSYS
466                          && !(current->sighand->action[signr-1].sa.sa_flags
467                               & SA_RESTART))) {
468                         regs->gprs[2] = -EINTR;
469                         regs->psw.addr = continue_addr;
470                 }
471         }
472
473         if (signr > 0) {
474                 /* Whee!  Actually deliver the signal.  */
475 #ifdef CONFIG_COMPAT
476                 if (test_thread_flag(TIF_31BIT)) {
477                         extern int handle_signal32(unsigned long sig,
478                                                    struct k_sigaction *ka,
479                                                    siginfo_t *info,
480                                                    sigset_t *oldset,
481                                                    struct pt_regs *regs);
482                         if (handle_signal32(
483                                     signr, &ka, &info, oldset, regs) == 0) {
484                                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
485                                         clear_thread_flag(TIF_RESTORE_SIGMASK);
486                         }
487                         return;
488                 }
489 #endif
490                 if (handle_signal(signr, &ka, &info, oldset, regs) == 0) {
491                         /*
492                          * A signal was successfully delivered; the saved
493                          * sigmask will have been stored in the signal frame,
494                          * and will be restored by sigreturn, so we can simply
495                          * clear the TIF_RESTORE_SIGMASK flag.
496                          */
497                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
498                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
499                 }
500                 return;
501         }
502
503         /*
504          * If there's no signal to deliver, we just put the saved sigmask back.
505          */
506         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
507                 clear_thread_flag(TIF_RESTORE_SIGMASK);
508                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
509         }
510
511         /* Restart a different system call. */
512         if (retval == -ERESTART_RESTARTBLOCK
513             && regs->psw.addr == continue_addr) {
514                 regs->gprs[2] = __NR_restart_syscall;
515                 set_thread_flag(TIF_RESTART_SVC);
516         }
517 }