arch/mips/kernel/signal.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1991, 1992  Linus Torvalds
   7  * Copyright (C) 1994 - 2000  Ralf Baechle
   8  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
   9  */
  10 #include <linux/config.h>
  11 #include <linux/cache.h>
  12 #include <linux/sched.h>
  13 #include <linux/mm.h>
  14 #include <linux/personality.h>
  15 #include <linux/smp.h>
  16 #include <linux/smp_lock.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/compiler.h>
  24
  25 #include <asm/abi.h>
  26 #include <asm/asm.h>
  27 #include <linux/bitops.h>
  28 #include <asm/cacheflush.h>
  29 #include <asm/fpu.h>
  30 #include <asm/sim.h>
  31 #include <asm/uaccess.h>
  32 #include <asm/ucontext.h>
  33 #include <asm/cpu-features.h>
  34 #include <asm/war.h>
  35
  36 #include "signal-common.h"
  37
  38 #define DEBUG_SIG 0
  39
  40 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  41
  42 /*
  43  * Atomically swap in the new signal mask, and wait for a signal.
  44  */
  45
  46 #ifdef CONFIG_TRAD_SIGNALS
  47 save_static_function(sys_sigsuspend);
  48 __attribute_used__ noinline static int
  49 _sys_sigsuspend(nabi_no_regargs struct pt_regs regs)
  50 {
  51         sigset_t newset;
  52         sigset_t __user *uset;
  53
  54         uset = (sigset_t __user *) regs.regs[4];
  55         if (copy_from_user(&newset, uset, sizeof(sigset_t)))
  56                 return -EFAULT;
  57         sigdelsetmask(&newset, ~_BLOCKABLE);
  58
  59         spin_lock_irq(&current->sighand->siglock);
  60         current->saved_sigmask = current->blocked;
  61         current->blocked = newset;
  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         return -ERESTARTNOHAND;
  69 }
  70 #endif
  71
  72 save_static_function(sys_rt_sigsuspend);
  73 __attribute_used__ noinline static int
  74 _sys_rt_sigsuspend(nabi_no_regargs struct pt_regs regs)
  75 {
  76         sigset_t newset;
  77         sigset_t __user *unewset;
  78         size_t sigsetsize;
  79
  80         /* XXX Don't preclude handling different sized sigset_t's.  */
  81         sigsetsize = regs.regs[5];
  82         if (sigsetsize != sizeof(sigset_t))
  83                 return -EINVAL;
  84
  85         unewset = (sigset_t __user *) regs.regs[4];
  86         if (copy_from_user(&newset, unewset, sizeof(newset)))
  87                 return -EFAULT;
  88         sigdelsetmask(&newset, ~_BLOCKABLE);
  89
  90         spin_lock_irq(&current->sighand->siglock);
  91         current->saved_sigmask = current->blocked;
  92         current->blocked = newset;
  93         recalc_sigpending();
  94         spin_unlock_irq(&current->sighand->siglock);
  95
  96         current->state = TASK_INTERRUPTIBLE;
  97         schedule();
  98         set_thread_flag(TIF_RESTORE_SIGMASK);
  99         return -ERESTARTNOHAND;
 100 }
 101
 102 #ifdef CONFIG_TRAD_SIGNALS
 103 asmlinkage int sys_sigaction(int sig, const struct sigaction *act,
 104         struct sigaction *oact)
 105 {
 106         struct k_sigaction new_ka, old_ka;
 107         int ret;
 108         int err = 0;
 109
 110         if (act) {
 111                 old_sigset_t mask;
 112
 113                 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
 114                         return -EFAULT;
 115                 err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
 116                 err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 117                 err |= __get_user(mask, &act->sa_mask.sig[0]);
 118                 if (err)
 119                         return -EFAULT;
 120
 121                 siginitset(&new_ka.sa.sa_mask, mask);
 122         }
 123
 124         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 125
 126         if (!ret && oact) {
 127                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
 128                         return -EFAULT;
 129                 err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 130                 err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
 131                 err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
 132                 err |= __put_user(0, &oact->sa_mask.sig[1]);
 133                 err |= __put_user(0, &oact->sa_mask.sig[2]);
 134                 err |= __put_user(0, &oact->sa_mask.sig[3]);
 135                 if (err)
 136                         return -EFAULT;
 137         }
 138
 139         return ret;
 140 }
 141 #endif
 142
 143 asmlinkage int sys_sigaltstack(nabi_no_regargs struct pt_regs regs)
 144 {
 145         const stack_t __user *uss = (const stack_t __user *) regs.regs[4];
 146         stack_t __user *uoss = (stack_t __user *) regs.regs[5];
 147         unsigned long usp = regs.regs[29];
 148
 149         return do_sigaltstack(uss, uoss, usp);
 150 }
 151
 152 /*
 153  * Horribly complicated - with the bloody RM9000 workarounds enabled
 154  * the signal trampolines is moving to the end of the structure so we can
 155  * increase the alignment without breaking software compatibility.
 156  */
 157 #ifdef CONFIG_TRAD_SIGNALS
 158 struct sigframe {
 159         u32 sf_ass[4];                  /* argument save space for o32 */
 160 #if ICACHE_REFILLS_WORKAROUND_WAR
 161         u32 sf_pad[2];
 162 #else
 163         u32 sf_code[2];                 /* signal trampoline */
 164 #endif
 165         struct sigcontext sf_sc;
 166         sigset_t sf_mask;
 167 #if ICACHE_REFILLS_WORKAROUND_WAR
 168         u32 sf_code[8] ____cacheline_aligned;   /* signal trampoline */
 169 #endif
 170 };
 171 #endif
 172
 173 struct rt_sigframe {
 174         u32 rs_ass[4];                  /* argument save space for o32 */
 175 #if ICACHE_REFILLS_WORKAROUND_WAR
 176         u32 rs_pad[2];
 177 #else
 178         u32 rs_code[2];                 /* signal trampoline */
 179 #endif
 180         struct siginfo rs_info;
 181         struct ucontext rs_uc;
 182 #if ICACHE_REFILLS_WORKAROUND_WAR
 183         u32 rs_code[8] ____cacheline_aligned;   /* signal trampoline */
 184 #endif
 185 };
 186
 187 #ifdef CONFIG_TRAD_SIGNALS
 188 save_static_function(sys_sigreturn);
 189 __attribute_used__ noinline static void
 190 _sys_sigreturn(nabi_no_regargs struct pt_regs regs)
 191 {
 192         struct sigframe __user *frame;
 193         sigset_t blocked;
 194
 195         frame = (struct sigframe __user *) regs.regs[29];
 196         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 197                 goto badframe;
 198         if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
 199                 goto badframe;
 200
 201         sigdelsetmask(&blocked, ~_BLOCKABLE);
 202         spin_lock_irq(&current->sighand->siglock);
 203         current->blocked = blocked;
 204         recalc_sigpending();
 205         spin_unlock_irq(&current->sighand->siglock);
 206
 207         if (restore_sigcontext(&regs, &frame->sf_sc))
 208                 goto badframe;
 209
 210         /*
 211          * Don't let your children do this ...
 212          */
 213         __asm__ __volatile__(
 214                 "move\t$29, %0\n\t"
 215                 "j\tsyscall_exit"
 216                 :/* no outputs */
 217                 :"r" (&regs));
 218         /* Unreached */
 219
 220 badframe:
 221         force_sig(SIGSEGV, current);
 222 }
 223 #endif /* CONFIG_TRAD_SIGNALS */
 224
 225 save_static_function(sys_rt_sigreturn);
 226 __attribute_used__ noinline static void
 227 _sys_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
 228 {
 229         struct rt_sigframe __user *frame;
 230         sigset_t set;
 231         stack_t st;
 232
 233         frame = (struct rt_sigframe __user *) regs.regs[29];
 234         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 235                 goto badframe;
 236         if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
 237                 goto badframe;
 238
 239         sigdelsetmask(&set, ~_BLOCKABLE);
 240         spin_lock_irq(&current->sighand->siglock);
 241         current->blocked = set;
 242         recalc_sigpending();
 243         spin_unlock_irq(&current->sighand->siglock);
 244
 245         if (restore_sigcontext(&regs, &frame->rs_uc.uc_mcontext))
 246                 goto badframe;
 247
 248         if (__copy_from_user(&st, &frame->rs_uc.uc_stack, sizeof(st)))
 249                 goto badframe;
 250         /* It is more difficult to avoid calling this function than to
 251            call it and ignore errors.  */
 252         do_sigaltstack((stack_t __user *)&st, NULL, regs.regs[29]);
 253
 254         /*
 255          * Don't let your children do this ...
 256          */
 257         __asm__ __volatile__(
 258                 "move\t$29, %0\n\t"
 259                 "j\tsyscall_exit"
 260                 :/* no outputs */
 261                 :"r" (&regs));
 262         /* Unreached */
 263
 264 badframe:
 265         force_sig(SIGSEGV, current);
 266 }
 267
 268 #ifdef CONFIG_TRAD_SIGNALS
 269 int setup_frame(struct k_sigaction * ka, struct pt_regs *regs,
 270         int signr, sigset_t *set)
 271 {
 272         struct sigframe __user *frame;
 273         int err = 0;
 274
 275         frame = get_sigframe(ka, regs, sizeof(*frame));
 276         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 277                 goto give_sigsegv;
 278
 279         install_sigtramp(frame->sf_code, __NR_sigreturn);
 280
 281         err |= setup_sigcontext(regs, &frame->sf_sc);
 282         err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
 283         if (err)
 284                 goto give_sigsegv;
 285
 286         /*
 287          * Arguments to signal handler:
 288          *
 289          *   a0 = signal number
 290          *   a1 = 0 (should be cause)
 291          *   a2 = pointer to struct sigcontext
 292          *
 293          * $25 and c0_epc point to the signal handler, $29 points to the
 294          * struct sigframe.
 295          */
 296         regs->regs[ 4] = signr;
 297         regs->regs[ 5] = 0;
 298         regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 299         regs->regs[29] = (unsigned long) frame;
 300         regs->regs[31] = (unsigned long) frame->sf_code;
 301         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 302
 303 #if DEBUG_SIG
 304         printk("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%p\n",
 305                current->comm, current->pid,
 306                frame, regs->cp0_epc, frame->regs[31]);
 307 #endif
 308         return 0;
 309
 310 give_sigsegv:
 311         force_sigsegv(signr, current);
 312         return -EFAULT;
 313 }
 314 #endif
 315
 316 int setup_rt_frame(struct k_sigaction * ka, struct pt_regs *regs,
 317         int signr, sigset_t *set, siginfo_t *info)
 318 {
 319         struct rt_sigframe __user *frame;
 320         int err = 0;
 321
 322         frame = get_sigframe(ka, regs, sizeof(*frame));
 323         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 324                 goto give_sigsegv;
 325
 326         install_sigtramp(frame->rs_code, __NR_rt_sigreturn);
 327
 328         /* Create siginfo.  */
 329         err |= copy_siginfo_to_user(&frame->rs_info, info);
 330
 331         /* Create the ucontext.  */
 332         err |= __put_user(0, &frame->rs_uc.uc_flags);
 333         err |= __put_user(NULL, &frame->rs_uc.uc_link);
 334         err |= __put_user((void *)current->sas_ss_sp,
 335                           &frame->rs_uc.uc_stack.ss_sp);
 336         err |= __put_user(sas_ss_flags(regs->regs[29]),
 337                           &frame->rs_uc.uc_stack.ss_flags);
 338         err |= __put_user(current->sas_ss_size,
 339                           &frame->rs_uc.uc_stack.ss_size);
 340         err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
 341         err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
 342
 343         if (err)
 344                 goto give_sigsegv;
 345
 346         /*
 347          * Arguments to signal handler:
 348          *
 349          *   a0 = signal number
 350          *   a1 = 0 (should be cause)
 351          *   a2 = pointer to ucontext
 352          *
 353          * $25 and c0_epc point to the signal handler, $29 points to
 354          * the struct rt_sigframe.
 355          */
 356         regs->regs[ 4] = signr;
 357         regs->regs[ 5] = (unsigned long) &frame->rs_info;
 358         regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 359         regs->regs[29] = (unsigned long) frame;
 360         regs->regs[31] = (unsigned long) frame->rs_code;
 361         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 362
 363 #if DEBUG_SIG
 364         printk("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%p\n",
 365                current->comm, current->pid,
 366                frame, regs->cp0_epc, regs->regs[31]);
 367 #endif
 368         return 0;
 369
 370 give_sigsegv:
 371         force_sigsegv(signr, current);
 372         return -EFAULT;
 373 }
 374
 375 static inline int handle_signal(unsigned long sig, siginfo_t *info,
 376         struct k_sigaction *ka, sigset_t *oldset, struct pt_regs *regs)
 377 {
 378         int ret;
 379
 380         switch(regs->regs[0]) {
 381         case ERESTART_RESTARTBLOCK:
 382         case ERESTARTNOHAND:
 383                 regs->regs[2] = EINTR;
 384                 break;
 385         case ERESTARTSYS:
 386                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 387                         regs->regs[2] = EINTR;
 388                         break;
 389                 }
 390         /* fallthrough */
 391         case ERESTARTNOINTR:            /* Userland will reload $v0.  */
 392                 regs->regs[7] = regs->regs[26];
 393                 regs->cp0_epc -= 8;
 394         }
 395
 396         regs->regs[0] = 0;              /* Don't deal with this again.  */
 397
 398         if (sig_uses_siginfo(ka))
 399                 ret = current->thread.abi->setup_rt_frame(ka, regs, sig, oldset, info);
 400         else
 401                 ret = current->thread.abi->setup_frame(ka, regs, sig, oldset);
 402
 403         spin_lock_irq(&current->sighand->siglock);
 404         sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 405         if (!(ka->sa.sa_flags & SA_NODEFER))
 406                 sigaddset(&current->blocked,sig);
 407         recalc_sigpending();
 408         spin_unlock_irq(&current->sighand->siglock);
 409
 410         return ret;
 411 }
 412
 413 void do_signal(struct pt_regs *regs)
 414 {
 415         struct k_sigaction ka;
 416         sigset_t *oldset;
 417         siginfo_t info;
 418         int signr;
 419
 420         /*
 421          * We want the common case to go fast, which is why we may in certain
 422          * cases get here from kernel mode. Just return without doing anything
 423          * if so.
 424          */
 425         if (!user_mode(regs))
 426                 return;
 427
 428         if (try_to_freeze())
 429                 goto no_signal;
 430
 431         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 432                 oldset = &current->saved_sigmask;
 433         else
 434                 oldset = &current->blocked;
 435
 436
 437         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 438         if (signr > 0) {
 439                 /* Whee!  Actually deliver the signal.  */
 440                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 441                         /*
 442                          * A signal was successfully delivered; the saved
 443                          * sigmask will have been stored in the signal frame,
 444                          * and will be restored by sigreturn, so we can simply
 445                          * clear the TIF_RESTORE_SIGMASK flag.
 446                          */
 447                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 448                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 449                 }
 450         }
 451
 452 no_signal:
 453         /*
 454          * Who's code doesn't conform to the restartable syscall convention
 455          * dies here!!!  The li instruction, a single machine instruction,
 456          * must directly be followed by the syscall instruction.
 457          */
 458         if (regs->regs[0]) {
 459                 if (regs->regs[2] == ERESTARTNOHAND ||
 460                     regs->regs[2] == ERESTARTSYS ||
 461                     regs->regs[2] == ERESTARTNOINTR) {
 462                         regs->regs[7] = regs->regs[26];
 463                         regs->cp0_epc -= 8;
 464                 }
 465                 if (regs->regs[2] == ERESTART_RESTARTBLOCK) {
 466                         regs->regs[2] = __NR_restart_syscall;
 467                         regs->regs[7] = regs->regs[26];
 468                         regs->cp0_epc -= 4;
 469                 }
 470         }
 471
 472         /*
 473          * If there's no signal to deliver, we just put the saved sigmask
 474          * back
 475          */
 476         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 477                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 478                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 479         }
 480 }
 481
 482 /*
 483  * notification of userspace execution resumption
 484  * - triggered by the TIF_WORK_MASK flags
 485  */
 486 asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 487         __u32 thread_info_flags)
 488 {
 489         /* deal with pending signal delivery */
 490         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 491                 current->thread.abi->do_signal(regs);
 492 }