arch/ia64/kernel/signal.c

   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 <linux/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->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, const 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 1;
 313 }
 314
 315 static long
 316 setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
 317 {
 318         extern char __kernel_sigtramp[];
 319         unsigned long tramp_addr, new_rbs = 0, new_sp;
 320         struct sigframe __user *frame;
 321         long err;
 322
 323         new_sp = scr->pt.r12;
 324         tramp_addr = (unsigned long) __kernel_sigtramp;
 325         if (ksig->ka.sa.sa_flags & SA_ONSTACK) {
 326                 int onstack = sas_ss_flags(new_sp);
 327
 328                 if (onstack == 0) {
 329                         new_sp = current->sas_ss_sp + current->sas_ss_size;
 330                         /*
 331                          * We need to check for the register stack being on the
 332                          * signal stack separately, because it's switched
 333                          * separately (memory stack is switched in the kernel,
 334                          * register stack is switched in the signal trampoline).
 335                          */
 336                         if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
 337                                 new_rbs = ALIGN(current->sas_ss_sp,
 338                                                 sizeof(long));
 339                 } else if (onstack == SS_ONSTACK) {
 340                         unsigned long check_sp;
 341
 342                         /*
 343                          * If we are on the alternate signal stack and would
 344                          * overflow it, don't. Return an always-bogus address
 345                          * instead so we will die with SIGSEGV.
 346                          */
 347                         check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;
 348                         if (!likely(on_sig_stack(check_sp)))
 349                                 return force_sigsegv_info(ksig->sig, (void __user *)
 350                                                           check_sp);
 351                 }
 352         }
 353         frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
 354
 355         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 356                 return force_sigsegv_info(ksig->sig, frame);
 357
 358         err  = __put_user(ksig->sig, &frame->arg0);
 359         err |= __put_user(&frame->info, &frame->arg1);
 360         err |= __put_user(&frame->sc, &frame->arg2);
 361         err |= __put_user(new_rbs, &frame->sc.sc_rbs_base);
 362         err |= __put_user(0, &frame->sc.sc_loadrs);     /* initialize to zero */
 363         err |= __put_user(ksig->ka.sa.sa_handler, &frame->handler);
 364
 365         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 366
 367         err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12);
 368         err |= setup_sigcontext(&frame->sc, set, scr);
 369
 370         if (unlikely(err))
 371                 return force_sigsegv_info(ksig->sig, frame);
 372
 373         scr->pt.r12 = (unsigned long) frame - 16;       /* new stack pointer */
 374         scr->pt.ar_fpsr = FPSR_DEFAULT;                 /* reset fpsr for signal handler */
 375         scr->pt.cr_iip = tramp_addr;
 376         ia64_psr(&scr->pt)->ri = 0;                     /* start executing in first slot */
 377         ia64_psr(&scr->pt)->be = 0;                     /* force little-endian byte-order */
 378         /*
 379          * Force the interruption function mask to zero.  This has no effect when a
 380          * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is
 381          * ignored), but it has the desirable effect of making it possible to deliver a
 382          * signal with an incomplete register frame (which happens when a mandatory RSE
 383          * load faults).  Furthermore, it has no negative effect on the getting the user's
 384          * dirty partition preserved, because that's governed by scr->pt.loadrs.
 385          */
 386         scr->pt.cr_ifs = (1UL << 63);
 387
 388         /*
 389          * Note: this affects only the NaT bits of the scratch regs (the ones saved in
 390          * pt_regs), which is exactly what we want.
 391          */
 392         scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */
 393
 394 #if DEBUG_SIG
 395         printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n",
 396                current->comm, current->pid, ksig->sig, scr->pt.r12, frame->sc.sc_ip, frame->handler);
 397 #endif
 398         return 0;
 399 }
 400
 401 static long
 402 handle_signal (struct ksignal *ksig, struct sigscratch *scr)
 403 {
 404         int ret = setup_frame(ksig, sigmask_to_save(), scr);
 405
 406         if (!ret)
 407                 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 408
 409         return ret;
 410 }
 411
 412 /*
 413  * Note that `init' is a special process: it doesn't get signals it doesn't want to
 414  * handle.  Thus you cannot kill init even with a SIGKILL even by mistake.
 415  */
 416 void
 417 ia64_do_signal (struct sigscratch *scr, long in_syscall)
 418 {
 419         long restart = in_syscall;
 420         long errno = scr->pt.r8;
 421         struct ksignal ksig;
 422
 423         /*
 424          * This only loops in the rare cases of handle_signal() failing, in which case we
 425          * need to push through a forced SIGSEGV.
 426          */
 427         while (1) {
 428                 get_signal(&ksig);
 429
 430                 /*
 431                  * get_signal_to_deliver() may have run a debugger (via notify_parent())
 432                  * and the debugger may have modified the state (e.g., to arrange for an
 433                  * inferior call), thus it's important to check for restarting _after_
 434                  * get_signal_to_deliver().
 435                  */
 436                 if ((long) scr->pt.r10 != -1)
 437                         /*
 438                          * A system calls has to be restarted only if one of the error codes
 439                          * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned.  If r10
 440                          * isn't -1 then r8 doesn't hold an error code and we don't need to
 441                          * restart the syscall, so we can clear the "restart" flag here.
 442                          */
 443                         restart = 0;
 444
 445                 if (ksig.sig <= 0)
 446                         break;
 447
 448                 if (unlikely(restart)) {
 449                         switch (errno) {
 450                               case ERESTART_RESTARTBLOCK:
 451                               case ERESTARTNOHAND:
 452                                 scr->pt.r8 = EINTR;
 453                                 /* note: scr->pt.r10 is already -1 */
 454                                 break;
 455
 456                               case ERESTARTSYS:
 457                                 if ((ksig.ka.sa.sa_flags & SA_RESTART) == 0) {
 458                                         scr->pt.r8 = EINTR;
 459                                         /* note: scr->pt.r10 is already -1 */
 460                                         break;
 461                                 }
 462                               case ERESTARTNOINTR:
 463                                 ia64_decrement_ip(&scr->pt);
 464                                 restart = 0; /* don't restart twice if handle_signal() fails... */
 465                         }
 466                 }
 467
 468                 /*
 469                  * Whee!  Actually deliver the signal.  If the delivery failed, we need to
 470                  * continue to iterate in this loop so we can deliver the SIGSEGV...
 471                  */
 472                 if (handle_signal(&ksig, scr))
 473                         return;
 474         }
 475
 476         /* Did we come from a system call? */
 477         if (restart) {
 478                 /* Restart the system call - no handlers present */
 479                 if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR
 480                     || errno == ERESTART_RESTARTBLOCK)
 481                 {
 482                         /*
 483                          * Note: the syscall number is in r15 which is saved in
 484                          * pt_regs so all we need to do here is adjust ip so that
 485                          * the "break" instruction gets re-executed.
 486                          */
 487                         ia64_decrement_ip(&scr->pt);
 488                         if (errno == ERESTART_RESTARTBLOCK)
 489                                 scr->pt.r15 = __NR_restart_syscall;
 490                 }
 491         }
 492
 493         /* if there's no signal to deliver, we just put the saved sigmask
 494          * back */
 495         restore_saved_sigmask();
 496 }