Merge branch 'upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/linville...
[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                         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 }