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TOMOYO Linux Cross Reference
Linux/arch/ia64/kernel/signal.c

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  1 /*
  2  * Architecture-specific signal handling support.
  3  *
  4  * Copyright (C) 1999-2004 Hewlett-Packard Co
  5  *      David Mosberger-Tang <davidm@hpl.hp.com>
  6  *
  7  * Derived from i386 and Alpha versions.
  8  */
  9 
 10 #include <linux/errno.h>
 11 #include <linux/kernel.h>
 12 #include <linux/mm.h>
 13 #include <linux/ptrace.h>
 14 #include <linux/tracehook.h>
 15 #include <linux/sched.h>
 16 #include <linux/signal.h>
 17 #include <linux/smp.h>
 18 #include <linux/stddef.h>
 19 #include <linux/tty.h>
 20 #include <linux/binfmts.h>
 21 #include <linux/unistd.h>
 22 #include <linux/wait.h>
 23 
 24 #include <asm/intrinsics.h>
 25 #include <asm/uaccess.h>
 26 #include <asm/rse.h>
 27 #include <asm/sigcontext.h>
 28 
 29 #include "sigframe.h"
 30 
 31 #define DEBUG_SIG       0
 32 #define STACK_ALIGN     16              /* minimal alignment for stack pointer */
 33 
 34 #if _NSIG_WORDS > 1
 35 # define PUT_SIGSET(k,u)        __copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t))
 36 # define GET_SIGSET(k,u)        __copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t))
 37 #else
 38 # define PUT_SIGSET(k,u)        __put_user((k)->sig[0], &(u)->sig[0])
 39 # define GET_SIGSET(k,u)        __get_user((k)->sig[0], &(u)->sig[0])
 40 #endif
 41 
 42 static long
 43 restore_sigcontext (struct sigcontext __user *sc, struct sigscratch *scr)
 44 {
 45         unsigned long ip, flags, nat, um, cfm, rsc;
 46         long err;
 47 
 48         /* Always make any pending restarted system calls return -EINTR */
 49         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 50 
 51         /* restore scratch that always needs gets updated during signal delivery: */
 52         err  = __get_user(flags, &sc->sc_flags);
 53         err |= __get_user(nat, &sc->sc_nat);
 54         err |= __get_user(ip, &sc->sc_ip);                      /* instruction pointer */
 55         err |= __get_user(cfm, &sc->sc_cfm);
 56         err |= __get_user(um, &sc->sc_um);                      /* user mask */
 57         err |= __get_user(rsc, &sc->sc_ar_rsc);
 58         err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat);
 59         err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);
 60         err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
 61         err |= __get_user(scr->pt.pr, &sc->sc_pr);              /* predicates */
 62         err |= __get_user(scr->pt.b0, &sc->sc_br[0]);           /* b0 (rp) */
 63         err |= __get_user(scr->pt.b6, &sc->sc_br[6]);           /* b6 */
 64         err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 8); /* r1 */
 65         err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8);       /* r8-r11 */
 66         err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 2*8);     /* r12-r13 */
 67         err |= __copy_from_user(&scr->pt.r15, &sc->sc_gr[15], 8);       /* r15 */
 68 
 69         scr->pt.cr_ifs = cfm | (1UL << 63);
 70         scr->pt.ar_rsc = rsc | (3 << 2); /* force PL3 */
 71 
 72         /* establish new instruction pointer: */
 73         scr->pt.cr_iip = ip & ~0x3UL;
 74         ia64_psr(&scr->pt)->ri = ip & 0x3;
 75         scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM);
 76 
 77         scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat);
 78 
 79         if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
 80                 /* Restore most scratch-state only when not in syscall. */
 81                 err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);              /* ar.ccv */
 82                 err |= __get_user(scr->pt.b7, &sc->sc_br[7]);                   /* b7 */
 83                 err |= __get_user(scr->pt.r14, &sc->sc_gr[14]);                 /* r14 */
 84                 err |= __copy_from_user(&scr->pt.ar_csd, &sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */
 85                 err |= __copy_from_user(&scr->pt.r2, &sc->sc_gr[2], 2*8);       /* r2-r3 */
 86                 err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8);    /* r16-r31 */
 87         }
 88 
 89         if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) {
 90                 struct ia64_psr *psr = ia64_psr(&scr->pt);
 91 
 92                 err |= __copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16);
 93                 psr->mfh = 0;   /* drop signal handler's fph contents... */
 94                 preempt_disable();
 95                 if (psr->dfh)
 96                         ia64_drop_fpu(current);
 97                 else {
 98                         /* We already own the local fph, otherwise psr->dfh wouldn't be 0.  */
 99                         __ia64_load_fpu(current->thread.fph);
100                         ia64_set_local_fpu_owner(current);
101                 }
102                 preempt_enable();
103         }
104         return err;
105 }
106 
107 int
108 copy_siginfo_to_user (siginfo_t __user *to, siginfo_t *from)
109 {
110         if (!access_ok(VERIFY_WRITE, to, sizeof(siginfo_t)))
111                 return -EFAULT;
112         if (from->si_code < 0) {
113                 if (__copy_to_user(to, from, sizeof(siginfo_t)))
114                         return -EFAULT;
115                 return 0;
116         } else {
117                 int err;
118 
119                 /*
120                  * If you change siginfo_t structure, please be sure this code is fixed
121                  * accordingly.  It should never copy any pad contained in the structure
122                  * to avoid security leaks, but must copy the generic 3 ints plus the
123                  * relevant union member.
124                  */
125                 err = __put_user(from->si_signo, &to->si_signo);
126                 err |= __put_user(from->si_errno, &to->si_errno);
127                 err |= __put_user((short)from->si_code, &to->si_code);
128                 switch (from->si_code >> 16) {
129                       case __SI_FAULT >> 16:
130                         err |= __put_user(from->si_flags, &to->si_flags);
131                         err |= __put_user(from->si_isr, &to->si_isr);
132                       case __SI_POLL >> 16:
133                         err |= __put_user(from->si_addr, &to->si_addr);
134                         err |= __put_user(from->si_imm, &to->si_imm);
135                         break;
136                       case __SI_TIMER >> 16:
137                         err |= __put_user(from->si_tid, &to->si_tid);
138                         err |= __put_user(from->si_overrun, &to->si_overrun);
139                         err |= __put_user(from->si_ptr, &to->si_ptr);
140                         break;
141                       case __SI_RT >> 16:       /* Not generated by the kernel as of now.  */
142                       case __SI_MESGQ >> 16:
143                         err |= __put_user(from->si_uid, &to->si_uid);
144                         err |= __put_user(from->si_pid, &to->si_pid);
145                         err |= __put_user(from->si_ptr, &to->si_ptr);
146                         break;
147                       case __SI_CHLD >> 16:
148                         err |= __put_user(from->si_utime, &to->si_utime);
149                         err |= __put_user(from->si_stime, &to->si_stime);
150                         err |= __put_user(from->si_status, &to->si_status);
151                       default:
152                         err |= __put_user(from->si_uid, &to->si_uid);
153                         err |= __put_user(from->si_pid, &to->si_pid);
154                         break;
155                 }
156                 return err;
157         }
158 }
159 
160 long
161 ia64_rt_sigreturn (struct sigscratch *scr)
162 {
163         extern char ia64_strace_leave_kernel, ia64_leave_kernel;
164         struct sigcontext __user *sc;
165         struct siginfo si;
166         sigset_t set;
167         long retval;
168 
169         sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc;
170 
171         /*
172          * When we return to the previously executing context, r8 and r10 have already
173          * been setup the way we want them.  Indeed, if the signal wasn't delivered while
174          * in a system call, we must not touch r8 or r10 as otherwise user-level state
175          * could be corrupted.
176          */
177         retval = (long) &ia64_leave_kernel;
178         if (test_thread_flag(TIF_SYSCALL_TRACE)
179             || test_thread_flag(TIF_SYSCALL_AUDIT))
180                 /*
181                  * strace expects to be notified after sigreturn returns even though the
182                  * context to which we return may not be in the middle of a syscall.
183                  * Thus, the return-value that strace displays for sigreturn is
184                  * meaningless.
185                  */
186                 retval = (long) &ia64_strace_leave_kernel;
187 
188         if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
189                 goto give_sigsegv;
190 
191         if (GET_SIGSET(&set, &sc->sc_mask))
192                 goto give_sigsegv;
193 
194         set_current_blocked(&set);
195 
196         if (restore_sigcontext(sc, scr))
197                 goto give_sigsegv;
198 
199 #if DEBUG_SIG
200         printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
201                current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip);
202 #endif
203         if (restore_altstack(&sc->sc_stack))
204                 goto give_sigsegv;
205         return retval;
206 
207   give_sigsegv:
208         si.si_signo = SIGSEGV;
209         si.si_errno = 0;
210         si.si_code = SI_KERNEL;
211         si.si_pid = task_pid_vnr(current);
212         si.si_uid = from_kuid_munged(current_user_ns(), current_uid());
213         si.si_addr = sc;
214         force_sig_info(SIGSEGV, &si, current);
215         return retval;
216 }
217 
218 /*
219  * This does just the minimum required setup of sigcontext.
220  * Specifically, it only installs data that is either not knowable at
221  * the user-level or that gets modified before execution in the
222  * trampoline starts.  Everything else is done at the user-level.
223  */
224 static long
225 setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr)
226 {
227         unsigned long flags = 0, ifs, cfm, nat;
228         long err = 0;
229 
230         ifs = scr->pt.cr_ifs;
231 
232         if (on_sig_stack((unsigned long) sc))
233                 flags |= IA64_SC_FLAG_ONSTACK;
234         if ((ifs & (1UL << 63)) == 0)
235                 /* if cr_ifs doesn't have the valid bit set, we got here through a syscall */
236                 flags |= IA64_SC_FLAG_IN_SYSCALL;
237         cfm = ifs & ((1UL << 38) - 1);
238         ia64_flush_fph(current);
239         if ((current->thread.flags & IA64_THREAD_FPH_VALID)) {
240                 flags |= IA64_SC_FLAG_FPH_VALID;
241                 err = __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
242         }
243 
244         nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat);
245 
246         err |= __put_user(flags, &sc->sc_flags);
247         err |= __put_user(nat, &sc->sc_nat);
248         err |= PUT_SIGSET(mask, &sc->sc_mask);
249         err |= __put_user(cfm, &sc->sc_cfm);
250         err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um);
251         err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
252         err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat);            /* ar.unat */
253         err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);            /* ar.fpsr */
254         err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
255         err |= __put_user(scr->pt.pr, &sc->sc_pr);                      /* predicates */
256         err |= __put_user(scr->pt.b0, &sc->sc_br[0]);                   /* b0 (rp) */
257         err |= __put_user(scr->pt.b6, &sc->sc_br[6]);                   /* b6 */
258         err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8);           /* r1 */
259         err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8);         /* r8-r11 */
260         err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8);       /* r12-r13 */
261         err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8);         /* r15 */
262         err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip);
263 
264         if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
265                 /* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */
266                 err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);              /* ar.ccv */
267                 err |= __put_user(scr->pt.b7, &sc->sc_br[7]);                   /* b7 */
268                 err |= __put_user(scr->pt.r14, &sc->sc_gr[14]);                 /* r14 */
269                 err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */
270                 err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8);         /* r2-r3 */
271                 err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8);      /* r16-r31 */
272         }
273         return err;
274 }
275 
276 /*
277  * Check whether the register-backing store is already on the signal stack.
278  */
279 static inline int
280 rbs_on_sig_stack (unsigned long bsp)
281 {
282         return (bsp - current->sas_ss_sp < current->sas_ss_size);
283 }
284 
285 static long
286 force_sigsegv_info (int sig, void __user *addr)
287 {
288         unsigned long flags;
289         struct siginfo si;
290 
291         if (sig == SIGSEGV) {
292                 /*
293                  * Acquiring siglock around the sa_handler-update is almost
294                  * certainly overkill, but this isn't a
295                  * performance-critical path and I'd rather play it safe
296                  * here than having to debug a nasty race if and when
297                  * something changes in kernel/signal.c that would make it
298                  * no longer safe to modify sa_handler without holding the
299                  * lock.
300                  */
301                 spin_lock_irqsave(&current->sighand->siglock, flags);
302                 current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
303                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
304         }
305         si.si_signo = SIGSEGV;
306         si.si_errno = 0;
307         si.si_code = SI_KERNEL;
308         si.si_pid = task_pid_vnr(current);
309         si.si_uid = from_kuid_munged(current_user_ns(), current_uid());
310         si.si_addr = addr;
311         force_sig_info(SIGSEGV, &si, current);
312         return 0;
313 }
314 
315 static long
316 setup_frame (int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set,
317              struct sigscratch *scr)
318 {
319         extern char __kernel_sigtramp[];
320         unsigned long tramp_addr, new_rbs = 0, new_sp;
321         struct sigframe __user *frame;
322         long err;
323 
324         new_sp = scr->pt.r12;
325         tramp_addr = (unsigned long) __kernel_sigtramp;
326         if (ka->sa.sa_flags & SA_ONSTACK) {
327                 int onstack = sas_ss_flags(new_sp);
328 
329                 if (onstack == 0) {
330                         new_sp = current->sas_ss_sp + current->sas_ss_size;
331                         /*
332                          * We need to check for the register stack being on the
333                          * signal stack separately, because it's switched
334                          * separately (memory stack is switched in the kernel,
335                          * register stack is switched in the signal trampoline).
336                          */
337                         if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
338                                 new_rbs = ALIGN(current->sas_ss_sp,
339                                                 sizeof(long));
340                 } else if (onstack == SS_ONSTACK) {
341                         unsigned long check_sp;
342 
343                         /*
344                          * If we are on the alternate signal stack and would
345                          * overflow it, don't. Return an always-bogus address
346                          * instead so we will die with SIGSEGV.
347                          */
348                         check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;
349                         if (!likely(on_sig_stack(check_sp)))
350                                 return force_sigsegv_info(sig, (void __user *)
351                                                           check_sp);
352                 }
353         }
354         frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
355 
356         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
357                 return force_sigsegv_info(sig, frame);
358 
359         err  = __put_user(sig, &frame->arg0);
360         err |= __put_user(&frame->info, &frame->arg1);
361         err |= __put_user(&frame->sc, &frame->arg2);
362         err |= __put_user(new_rbs, &frame->sc.sc_rbs_base);
363         err |= __put_user(0, &frame->sc.sc_loadrs);     /* initialize to zero */
364         err |= __put_user(ka->sa.sa_handler, &frame->handler);
365 
366         err |= copy_siginfo_to_user(&frame->info, info);
367 
368         err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12);
369         err |= setup_sigcontext(&frame->sc, set, scr);
370 
371         if (unlikely(err))
372                 return force_sigsegv_info(sig, frame);
373 
374         scr->pt.r12 = (unsigned long) frame - 16;       /* new stack pointer */
375         scr->pt.ar_fpsr = FPSR_DEFAULT;                 /* reset fpsr for signal handler */
376         scr->pt.cr_iip = tramp_addr;
377         ia64_psr(&scr->pt)->ri = 0;                     /* start executing in first slot */
378         ia64_psr(&scr->pt)->be = 0;                     /* force little-endian byte-order */
379         /*
380          * Force the interruption function mask to zero.  This has no effect when a
381          * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is
382          * ignored), but it has the desirable effect of making it possible to deliver a
383          * signal with an incomplete register frame (which happens when a mandatory RSE
384          * load faults).  Furthermore, it has no negative effect on the getting the user's
385          * dirty partition preserved, because that's governed by scr->pt.loadrs.
386          */
387         scr->pt.cr_ifs = (1UL << 63);
388 
389         /*
390          * Note: this affects only the NaT bits of the scratch regs (the ones saved in
391          * pt_regs), which is exactly what we want.
392          */
393         scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */
394 
395 #if DEBUG_SIG
396         printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n",
397                current->comm, current->pid, sig, scr->pt.r12, frame->sc.sc_ip, frame->handler);
398 #endif
399         return 1;
400 }
401 
402 static long
403 handle_signal (unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
404                struct sigscratch *scr)
405 {
406         if (!setup_frame(sig, ka, info, sigmask_to_save(), scr))
407                 return 0;
408 
409         signal_delivered(sig, info, ka, &scr->pt,
410                                  test_thread_flag(TIF_SINGLESTEP));
411 
412         return 1;
413 }
414 
415 /*
416  * Note that `init' is a special process: it doesn't get signals it doesn't want to
417  * handle.  Thus you cannot kill init even with a SIGKILL even by mistake.
418  */
419 void
420 ia64_do_signal (struct sigscratch *scr, long in_syscall)
421 {
422         struct k_sigaction ka;
423         siginfo_t info;
424         long restart = in_syscall;
425         long errno = scr->pt.r8;
426 
427         /*
428          * This only loops in the rare cases of handle_signal() failing, in which case we
429          * need to push through a forced SIGSEGV.
430          */
431         while (1) {
432                 int signr = get_signal_to_deliver(&info, &ka, &scr->pt, NULL);
433 
434                 /*
435                  * get_signal_to_deliver() may have run a debugger (via notify_parent())
436                  * and the debugger may have modified the state (e.g., to arrange for an
437                  * inferior call), thus it's important to check for restarting _after_
438                  * get_signal_to_deliver().
439                  */
440                 if ((long) scr->pt.r10 != -1)
441                         /*
442                          * A system calls has to be restarted only if one of the error codes
443                          * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned.  If r10
444                          * isn't -1 then r8 doesn't hold an error code and we don't need to
445                          * restart the syscall, so we can clear the "restart" flag here.
446                          */
447                         restart = 0;
448 
449                 if (signr <= 0)
450                         break;
451 
452                 if (unlikely(restart)) {
453                         switch (errno) {
454                               case ERESTART_RESTARTBLOCK:
455                               case ERESTARTNOHAND:
456                                 scr->pt.r8 = EINTR;
457                                 /* note: scr->pt.r10 is already -1 */
458                                 break;
459 
460                               case ERESTARTSYS:
461                                 if ((ka.sa.sa_flags & SA_RESTART) == 0) {
462                                         scr->pt.r8 = EINTR;
463                                         /* note: scr->pt.r10 is already -1 */
464                                         break;
465                                 }
466                               case ERESTARTNOINTR:
467                                 ia64_decrement_ip(&scr->pt);
468                                 restart = 0; /* don't restart twice if handle_signal() fails... */
469                         }
470                 }
471 
472                 /*
473                  * Whee!  Actually deliver the signal.  If the delivery failed, we need to
474                  * continue to iterate in this loop so we can deliver the SIGSEGV...
475                  */
476                 if (handle_signal(signr, &ka, &info, scr))
477                         return;
478         }
479 
480         /* Did we come from a system call? */
481         if (restart) {
482                 /* Restart the system call - no handlers present */
483                 if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR
484                     || errno == ERESTART_RESTARTBLOCK)
485                 {
486                         /*
487                          * Note: the syscall number is in r15 which is saved in
488                          * pt_regs so all we need to do here is adjust ip so that
489                          * the "break" instruction gets re-executed.
490                          */
491                         ia64_decrement_ip(&scr->pt);
492                         if (errno == ERESTART_RESTARTBLOCK)
493                                 scr->pt.r15 = __NR_restart_syscall;
494                 }
495         }
496 
497         /* if there's no signal to deliver, we just put the saved sigmask
498          * back */
499         restore_saved_sigmask();
500 }
501 

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