arch/microblaze/kernel/signal.c

   1 /*
   2  * Signal handling
   3  *
   4  * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
   5  * Copyright (C) 2008-2009 PetaLogix
   6  * Copyright (C) 2003,2004 John Williams <jwilliams@itee.uq.edu.au>
   7  * Copyright (C) 2001 NEC Corporation
   8  * Copyright (C) 2001 Miles Bader <miles@gnu.org>
   9  * Copyright (C) 1999,2000 Niibe Yutaka & Kaz Kojima
  10  * Copyright (C) 1991,1992 Linus Torvalds
  11  *
  12  * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
  13  *
  14  * This file was was derived from the sh version, arch/sh/kernel/signal.c
  15  *
  16  * This file is subject to the terms and conditions of the GNU General
  17  * Public License. See the file COPYING in the main directory of this
  18  * archive for more details.
  19  */
  20
  21 #include <linux/sched.h>
  22 #include <linux/mm.h>
  23 #include <linux/smp.h>
  24 #include <linux/smp_lock.h>
  25 #include <linux/kernel.h>
  26 #include <linux/signal.h>
  27 #include <linux/errno.h>
  28 #include <linux/wait.h>
  29 #include <linux/ptrace.h>
  30 #include <linux/unistd.h>
  31 #include <linux/stddef.h>
  32 #include <linux/personality.h>
  33 #include <linux/percpu.h>
  34 #include <linux/linkage.h>
  35 #include <asm/entry.h>
  36 #include <asm/ucontext.h>
  37 #include <linux/uaccess.h>
  38 #include <asm/pgtable.h>
  39 #include <asm/pgalloc.h>
  40 #include <linux/syscalls.h>
  41 #include <asm/cacheflush.h>
  42 #include <asm/syscalls.h>
  43
  44 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  45
  46 asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_sycall);
  47
  48 /*
  49  * Atomically swap in the new signal mask, and wait for a signal.
  50  */
  51 asmlinkage int
  52 sys_sigsuspend(old_sigset_t mask, struct pt_regs *regs)
  53 {
  54         sigset_t saveset;
  55
  56         mask &= _BLOCKABLE;
  57         spin_lock_irq(&current->sighand->siglock);
  58         saveset = current->blocked;
  59         siginitset(&current->blocked, mask);
  60         recalc_sigpending();
  61         spin_unlock_irq(&current->sighand->siglock);
  62
  63         regs->r3 = -EINTR;
  64         while (1) {
  65                 current->state = TASK_INTERRUPTIBLE;
  66                 schedule();
  67                 if (do_signal(regs, &saveset, 1))
  68                         return -EINTR;
  69         }
  70 }
  71
  72 asmlinkage int
  73 sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize,
  74                 struct pt_regs *regs)
  75 {
  76         sigset_t saveset, newset;
  77
  78         /* XXX: Don't preclude handling different sized sigset_t's. */
  79         if (sigsetsize != sizeof(sigset_t))
  80                 return -EINVAL;
  81
  82         if (copy_from_user(&newset, unewset, sizeof(newset)))
  83                 return -EFAULT;
  84         sigdelsetmask(&newset, ~_BLOCKABLE);
  85         spin_lock_irq(&current->sighand->siglock);
  86         saveset = current->blocked;
  87         current->blocked = newset;
  88         recalc_sigpending();
  89         spin_unlock_irq(&current->sighand->siglock);
  90
  91         regs->r3 = -EINTR;
  92         while (1) {
  93                 current->state = TASK_INTERRUPTIBLE;
  94                 schedule();
  95                 if (do_signal(regs, &saveset, 1))
  96                         return -EINTR;
  97         }
  98 }
  99
 100 asmlinkage int
 101 sys_sigaction(int sig, const struct old_sigaction *act,
 102                 struct old_sigaction *oact)
 103 {
 104         struct k_sigaction new_ka, old_ka;
 105         int ret;
 106
 107         if (act) {
 108                 old_sigset_t mask;
 109                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
 110                         __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
 111                         __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
 112                         return -EFAULT;
 113                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 114                 __get_user(mask, &act->sa_mask);
 115                 siginitset(&new_ka.sa.sa_mask, mask);
 116         }
 117
 118         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 119
 120         if (!ret && oact) {
 121                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
 122                         __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 123                         __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 124                         return -EFAULT;
 125                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 126                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 127         }
 128
 129         return ret;
 130 }
 131
 132 asmlinkage int
 133 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 134                 struct pt_regs *regs)
 135 {
 136         return do_sigaltstack(uss, uoss, regs->r1);
 137 }
 138
 139 /*
 140  * Do a signal return; undo the signal stack.
 141  */
 142
 143 struct sigframe {
 144         struct sigcontext sc;
 145         unsigned long extramask[_NSIG_WORDS-1];
 146         unsigned long tramp[2]; /* signal trampoline */
 147 };
 148
 149 struct rt_sigframe {
 150         struct siginfo info;
 151         struct ucontext uc;
 152         unsigned long tramp[2]; /* signal trampoline */
 153 };
 154
 155 static int restore_sigcontext(struct pt_regs *regs,
 156                                 struct sigcontext __user *sc, int *rval_p)
 157 {
 158         unsigned int err = 0;
 159
 160 #define COPY(x)         {err |= __get_user(regs->x, &sc->regs.x); }
 161         COPY(r0);
 162         COPY(r1);
 163         COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
 164         COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
 165         COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
 166         COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
 167         COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
 168         COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
 169         COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
 170         COPY(r30);      COPY(r31);
 171         COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
 172 #undef COPY
 173
 174         *rval_p = regs->r3;
 175
 176         return err;
 177 }
 178
 179 asmlinkage int sys_sigreturn(struct pt_regs *regs)
 180 {
 181         struct sigframe *frame =
 182                         (struct sigframe *)(regs->r1 + STATE_SAVE_ARG_SPACE);
 183
 184         sigset_t set;
 185         int rval;
 186
 187         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 188                 goto badframe;
 189
 190         if (__get_user(set.sig[0], &frame->sc.oldmask)
 191                 || (_NSIG_WORDS > 1
 192                 && __copy_from_user(&set.sig[1], &frame->extramask,
 193                                         sizeof(frame->extramask))))
 194                 goto badframe;
 195
 196         sigdelsetmask(&set, ~_BLOCKABLE);
 197
 198         spin_lock_irq(&current->sighand->siglock);
 199         current->blocked = set;
 200         recalc_sigpending();
 201         spin_unlock_irq(&current->sighand->siglock);
 202
 203         if (restore_sigcontext(regs, &frame->sc, &rval))
 204                 goto badframe;
 205         return rval;
 206
 207 badframe:
 208         force_sig(SIGSEGV, current);
 209         return 0;
 210 }
 211
 212 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 213 {
 214         struct rt_sigframe __user *frame =
 215                 (struct rt_sigframe __user *)(regs->r1 + STATE_SAVE_ARG_SPACE);
 216
 217         sigset_t set;
 218         int rval;
 219
 220         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 221                 goto badframe;
 222
 223         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 224                 goto badframe;
 225
 226         sigdelsetmask(&set, ~_BLOCKABLE);
 227         spin_lock_irq(&current->sighand->siglock);
 228         current->blocked = set;
 229         recalc_sigpending();
 230         spin_unlock_irq(&current->sighand->siglock);
 231
 232         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval))
 233                 goto badframe;
 234
 235         /* It is more difficult to avoid calling this function than to
 236          call it and ignore errors. */
 237         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->r1))
 238                 goto badframe;
 239
 240         return rval;
 241
 242 badframe:
 243         force_sig(SIGSEGV, current);
 244         return 0;
 245 }
 246
 247 /*
 248  * Set up a signal frame.
 249  */
 250
 251 static int
 252 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 253                 unsigned long mask)
 254 {
 255         int err = 0;
 256
 257 #define COPY(x)         {err |= __put_user(regs->x, &sc->regs.x); }
 258         COPY(r0);
 259         COPY(r1);
 260         COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
 261         COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
 262         COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
 263         COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
 264         COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
 265         COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
 266         COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
 267         COPY(r30);      COPY(r31);
 268         COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
 269 #undef COPY
 270
 271         err |= __put_user(mask, &sc->oldmask);
 272
 273         return err;
 274 }
 275
 276 /*
 277  * Determine which stack to use..
 278  */
 279 static inline void __user *
 280 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
 281 {
 282         /* Default to using normal stack */
 283         unsigned long sp = regs->r1;
 284
 285         if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && !on_sig_stack(sp))
 286                 sp = current->sas_ss_sp + current->sas_ss_size;
 287
 288         return (void __user *)((sp - frame_size) & -8UL);
 289 }
 290
 291 static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 292                         sigset_t *set, struct pt_regs *regs)
 293 {
 294         struct rt_sigframe __user *frame;
 295         int err = 0;
 296         int signal;
 297
 298         frame = get_sigframe(ka, regs, sizeof(*frame));
 299
 300         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 301                 goto give_sigsegv;
 302
 303         signal = current_thread_info()->exec_domain
 304                 && current_thread_info()->exec_domain->signal_invmap
 305                 && sig < 32
 306                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 307                 : sig;
 308
 309         if (info)
 310                 err |= copy_siginfo_to_user(&frame->info, info);
 311
 312         /* Create the ucontext. */
 313         err |= __put_user(0, &frame->uc.uc_flags);
 314         err |= __put_user(0, &frame->uc.uc_link);
 315         err |= __put_user((void *)current->sas_ss_sp,
 316                         &frame->uc.uc_stack.ss_sp);
 317         err |= __put_user(sas_ss_flags(regs->r1),
 318                         &frame->uc.uc_stack.ss_flags);
 319         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 320         err |= setup_sigcontext(&frame->uc.uc_mcontext,
 321                         regs, set->sig[0]);
 322         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 323
 324         /* Set up to return from userspace. If provided, use a stub
 325          already in userspace. */
 326         /* minus 8 is offset to cater for "rtsd r15,8" */
 327         if (ka->sa.sa_flags & SA_RESTORER) {
 328                 regs->r15 = ((unsigned long)ka->sa.sa_restorer)-8;
 329         } else {
 330                 /* addi r12, r0, __NR_sigreturn */
 331                 err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
 332                                 frame->tramp + 0);
 333                 /* brki r14, 0x8 */
 334                 err |= __put_user(0xb9cc0008, frame->tramp + 1);
 335
 336                 /* Return from sighandler will jump to the tramp.
 337                  Negative 8 offset because return is rtsd r15, 8 */
 338                 regs->r15 = ((unsigned long)frame->tramp)-8;
 339
 340                 __invalidate_cache_sigtramp((unsigned long)frame->tramp);
 341         }
 342
 343         if (err)
 344                 goto give_sigsegv;
 345
 346         /* Set up registers for signal handler */
 347         regs->r1 = (unsigned long) frame - STATE_SAVE_ARG_SPACE;
 348
 349         /* Signal handler args: */
 350         regs->r5 = signal; /* arg 0: signum */
 351         regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */
 352         regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */
 353         /* Offset to handle microblaze rtid r14, 0 */
 354         regs->pc = (unsigned long)ka->sa.sa_handler;
 355
 356         set_fs(USER_DS);
 357
 358 #ifdef DEBUG_SIG
 359         printk(KERN_INFO "SIG deliver (%s:%d): sp=%p pc=%08lx\n",
 360                 current->comm, current->pid, frame, regs->pc);
 361 #endif
 362
 363         return;
 364
 365 give_sigsegv:
 366         if (sig == SIGSEGV)
 367                 ka->sa.sa_handler = SIG_DFL;
 368         force_sig(SIGSEGV, current);
 369 }
 370
 371 /* Handle restarting system calls */
 372 static inline void
 373 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 374 {
 375         switch (regs->r3) {
 376         case -ERESTART_RESTARTBLOCK:
 377         case -ERESTARTNOHAND:
 378                 if (!has_handler)
 379                         goto do_restart;
 380                 regs->r3 = -EINTR;
 381                 break;
 382         case -ERESTARTSYS:
 383                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 384                         regs->r3 = -EINTR;
 385                         break;
 386         }
 387         /* fallthrough */
 388         case -ERESTARTNOINTR:
 389 do_restart:
 390                 /* offset of 4 bytes to re-execute trap (brki) instruction */
 391 #ifndef CONFIG_MMU
 392                 regs->pc -= 4;
 393 #else
 394                 /* offset of 8 bytes required = 4 for rtbd
 395                    offset, plus 4 for size of
 396                         "brki r14,8"
 397                    instruction. */
 398                 regs->pc -= 8;
 399 #endif
 400                 break;
 401         }
 402 }
 403
 404 /*
 405  * OK, we're invoking a handler
 406  */
 407
 408 static void
 409 handle_signal(unsigned long sig, struct k_sigaction *ka,
 410                 siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
 411 {
 412         /* Set up the stack frame */
 413         if (ka->sa.sa_flags & SA_SIGINFO)
 414                 setup_rt_frame(sig, ka, info, oldset, regs);
 415         else
 416                 setup_rt_frame(sig, ka, NULL, oldset, regs);
 417
 418         if (ka->sa.sa_flags & SA_ONESHOT)
 419                 ka->sa.sa_handler = SIG_DFL;
 420
 421         if (!(ka->sa.sa_flags & SA_NODEFER)) {
 422                 spin_lock_irq(&current->sighand->siglock);
 423                 sigorsets(&current->blocked,
 424                                 &current->blocked, &ka->sa.sa_mask);
 425                 sigaddset(&current->blocked, sig);
 426                 recalc_sigpending();
 427                 spin_unlock_irq(&current->sighand->siglock);
 428         }
 429 }
 430
 431 /*
 432  * Note that 'init' is a special process: it doesn't get signals it doesn't
 433  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 434  * mistake.
 435  *
 436  * Note that we go through the signals twice: once to check the signals that
 437  * the kernel can handle, and then we build all the user-level signal handling
 438  * stack-frames in one go after that.
 439  */
 440 int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_syscall)
 441 {
 442         siginfo_t info;
 443         int signr;
 444         struct k_sigaction ka;
 445 #ifdef DEBUG_SIG
 446         printk(KERN_INFO "do signal: %p %p %d\n", regs, oldset, in_syscall);
 447         printk(KERN_INFO "do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
 448                         regs->r12, current_thread_info()->flags);
 449 #endif
 450         /*
 451          * We want the common case to go fast, which
 452          * is why we may in certain cases get here from
 453          * kernel mode. Just return without doing anything
 454          * if so.
 455          */
 456         if (kernel_mode(regs))
 457                 return 1;
 458
 459         if (!oldset)
 460                 oldset = &current->blocked;
 461
 462         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 463         if (signr > 0) {
 464                 /* Whee! Actually deliver the signal. */
 465                 if (in_syscall)
 466                         handle_restart(regs, &ka, 1);
 467                 handle_signal(signr, &ka, &info, oldset, regs);
 468                 return 1;
 469         }
 470
 471         if (in_syscall)
 472                 handle_restart(regs, NULL, 0);
 473
 474         /* Did we come from a system call? */
 475         return 0;
 476 }