arch/tile/kernel/signal.c

   1 /*
   2  * Copyright (C) 1991, 1992  Linus Torvalds
   3  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   4  *
   5  *   This program is free software; you can redistribute it and/or
   6  *   modify it under the terms of the GNU General Public License
   7  *   as published by the Free Software Foundation, version 2.
   8  *
   9  *   This program is distributed in the hope that it will be useful, but
  10  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  12  *   NON INFRINGEMENT.  See the GNU General Public License for
  13  *   more details.
  14  */
  15
  16 #include <linux/sched.h>
  17 #include <linux/mm.h>
  18 #include <linux/smp.h>
  19 #include <linux/kernel.h>
  20 #include <linux/signal.h>
  21 #include <linux/errno.h>
  22 #include <linux/wait.h>
  23 #include <linux/unistd.h>
  24 #include <linux/stddef.h>
  25 #include <linux/personality.h>
  26 #include <linux/suspend.h>
  27 #include <linux/ptrace.h>
  28 #include <linux/elf.h>
  29 #include <linux/compat.h>
  30 #include <linux/syscalls.h>
  31 #include <linux/uaccess.h>
  32 #include <asm/processor.h>
  33 #include <asm/ucontext.h>
  34 #include <asm/sigframe.h>
  35 #include <asm/syscalls.h>
  36 #include <arch/interrupts.h>
  37
  38 #define DEBUG_SIG 0
  39
  40 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  41
  42 SYSCALL_DEFINE3(sigaltstack, const stack_t __user *, uss,
  43                 stack_t __user *, uoss, struct pt_regs *, regs)
  44 {
  45         return do_sigaltstack(uss, uoss, regs->sp);
  46 }
  47
  48
  49 /*
  50  * Do a signal return; undo the signal stack.
  51  */
  52
  53 int restore_sigcontext(struct pt_regs *regs,
  54                        struct sigcontext __user *sc)
  55 {
  56         int err = 0;
  57         int i;
  58
  59         /* Always make any pending restarted system calls return -EINTR */
  60         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  61
  62         /*
  63          * Enforce that sigcontext is like pt_regs, and doesn't mess
  64          * up our stack alignment rules.
  65          */
  66         BUILD_BUG_ON(sizeof(struct sigcontext) != sizeof(struct pt_regs));
  67         BUILD_BUG_ON(sizeof(struct sigcontext) % 8 != 0);
  68
  69         for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
  70                 err |= __get_user(regs->regs[i], &sc->gregs[i]);
  71
  72         /* Ensure that the PL is always set to USER_PL. */
  73         regs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(regs->ex1));
  74
  75         regs->faultnum = INT_SWINT_1_SIGRETURN;
  76
  77         return err;
  78 }
  79
  80 void signal_fault(const char *type, struct pt_regs *regs,
  81                   void __user *frame, int sig)
  82 {
  83         trace_unhandled_signal(type, regs, (unsigned long)frame, SIGSEGV);
  84         force_sigsegv(sig, current);
  85 }
  86
  87 /* The assembly shim for this function arranges to ignore the return value. */
  88 SYSCALL_DEFINE1(rt_sigreturn, struct pt_regs *, regs)
  89 {
  90         struct rt_sigframe __user *frame =
  91                 (struct rt_sigframe __user *)(regs->sp);
  92         sigset_t set;
  93
  94         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  95                 goto badframe;
  96         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  97                 goto badframe;
  98
  99         sigdelsetmask(&set, ~_BLOCKABLE);
 100         spin_lock_irq(&current->sighand->siglock);
 101         current->blocked = set;
 102         recalc_sigpending();
 103         spin_unlock_irq(&current->sighand->siglock);
 104
 105         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 106                 goto badframe;
 107
 108         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 109                 goto badframe;
 110
 111         return 0;
 112
 113 badframe:
 114         signal_fault("bad sigreturn frame", regs, frame, 0);
 115         return 0;
 116 }
 117
 118 /*
 119  * Set up a signal frame.
 120  */
 121
 122 int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 123 {
 124         int i, err = 0;
 125
 126         for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
 127                 err |= __put_user(regs->regs[i], &sc->gregs[i]);
 128
 129         return err;
 130 }
 131
 132 /*
 133  * Determine which stack to use..
 134  */
 135 static inline void __user *get_sigframe(struct k_sigaction *ka,
 136                                         struct pt_regs *regs,
 137                                         size_t frame_size)
 138 {
 139         unsigned long sp;
 140
 141         /* Default to using normal stack */
 142         sp = regs->sp;
 143
 144         /*
 145          * If we are on the alternate signal stack and would overflow
 146          * it, don't.  Return an always-bogus address instead so we
 147          * will die with SIGSEGV.
 148          */
 149         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 150                 return (void __user __force *)-1UL;
 151
 152         /* This is the X/Open sanctioned signal stack switching.  */
 153         if (ka->sa.sa_flags & SA_ONSTACK) {
 154                 if (sas_ss_flags(sp) == 0)
 155                         sp = current->sas_ss_sp + current->sas_ss_size;
 156         }
 157
 158         sp -= frame_size;
 159         /*
 160          * Align the stack pointer according to the TILE ABI,
 161          * i.e. so that on function entry (sp & 15) == 0.
 162          */
 163         sp &= -16UL;
 164         return (void __user *) sp;
 165 }
 166
 167 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 168                            sigset_t *set, struct pt_regs *regs)
 169 {
 170         unsigned long restorer;
 171         struct rt_sigframe __user *frame;
 172         int err = 0;
 173         int usig;
 174
 175         frame = get_sigframe(ka, regs, sizeof(*frame));
 176
 177         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 178                 goto give_sigsegv;
 179
 180         usig = current_thread_info()->exec_domain
 181                 && current_thread_info()->exec_domain->signal_invmap
 182                 && sig < 32
 183                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 184                 : sig;
 185
 186         /* Always write at least the signal number for the stack backtracer. */
 187         if (ka->sa.sa_flags & SA_SIGINFO) {
 188                 /* At sigreturn time, restore the callee-save registers too. */
 189                 err |= copy_siginfo_to_user(&frame->info, info);
 190                 regs->flags |= PT_FLAGS_RESTORE_REGS;
 191         } else {
 192                 err |= __put_user(info->si_signo, &frame->info.si_signo);
 193         }
 194
 195         /* Create the ucontext.  */
 196         err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
 197         err |= __put_user(0, &frame->uc.uc_flags);
 198         err |= __put_user(NULL, &frame->uc.uc_link);
 199         err |= __put_user((void __user *)(current->sas_ss_sp),
 200                           &frame->uc.uc_stack.ss_sp);
 201         err |= __put_user(sas_ss_flags(regs->sp),
 202                           &frame->uc.uc_stack.ss_flags);
 203         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 204         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 205         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 206         if (err)
 207                 goto give_sigsegv;
 208
 209         restorer = VDSO_BASE;
 210         if (ka->sa.sa_flags & SA_RESTORER)
 211                 restorer = (unsigned long) ka->sa.sa_restorer;
 212
 213         /*
 214          * Set up registers for signal handler.
 215          * Registers that we don't modify keep the value they had from
 216          * user-space at the time we took the signal.
 217          * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
 218          * since some things rely on this (e.g. glibc's debug/segfault.c).
 219          */
 220         regs->pc = (unsigned long) ka->sa.sa_handler;
 221         regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
 222         regs->sp = (unsigned long) frame;
 223         regs->lr = restorer;
 224         regs->regs[0] = (unsigned long) usig;
 225         regs->regs[1] = (unsigned long) &frame->info;
 226         regs->regs[2] = (unsigned long) &frame->uc;
 227         regs->flags |= PT_FLAGS_CALLER_SAVES;
 228
 229         /*
 230          * Notify any tracer that was single-stepping it.
 231          * The tracer may want to single-step inside the
 232          * handler too.
 233          */
 234         if (test_thread_flag(TIF_SINGLESTEP))
 235                 ptrace_notify(SIGTRAP);
 236
 237         return 0;
 238
 239 give_sigsegv:
 240         signal_fault("bad setup frame", regs, frame, sig);
 241         return -EFAULT;
 242 }
 243
 244 /*
 245  * OK, we're invoking a handler
 246  */
 247
 248 static int handle_signal(unsigned long sig, siginfo_t *info,
 249                          struct k_sigaction *ka, sigset_t *oldset,
 250                          struct pt_regs *regs)
 251 {
 252         int ret;
 253
 254         /* Are we from a system call? */
 255         if (regs->faultnum == INT_SWINT_1) {
 256                 /* If so, check system call restarting.. */
 257                 switch (regs->regs[0]) {
 258                 case -ERESTART_RESTARTBLOCK:
 259                 case -ERESTARTNOHAND:
 260                         regs->regs[0] = -EINTR;
 261                         break;
 262
 263                 case -ERESTARTSYS:
 264                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 265                                 regs->regs[0] = -EINTR;
 266                                 break;
 267                         }
 268                         /* fallthrough */
 269                 case -ERESTARTNOINTR:
 270                         /* Reload caller-saves to restore r0..r5 and r10. */
 271                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 272                         regs->regs[0] = regs->orig_r0;
 273                         regs->pc -= 8;
 274                 }
 275         }
 276
 277         /* Set up the stack frame */
 278 #ifdef CONFIG_COMPAT
 279         if (is_compat_task())
 280                 ret = compat_setup_rt_frame(sig, ka, info, oldset, regs);
 281         else
 282 #endif
 283                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 284         if (ret == 0) {
 285                 /* This code is only called from system calls or from
 286                  * the work_pending path in the return-to-user code, and
 287                  * either way we can re-enable interrupts unconditionally.
 288                  */
 289                 spin_lock_irq(&current->sighand->siglock);
 290                 sigorsets(&current->blocked,
 291                           &current->blocked, &ka->sa.sa_mask);
 292                 if (!(ka->sa.sa_flags & SA_NODEFER))
 293                         sigaddset(&current->blocked, sig);
 294                 recalc_sigpending();
 295                 spin_unlock_irq(&current->sighand->siglock);
 296         }
 297
 298         return ret;
 299 }
 300
 301 /*
 302  * Note that 'init' is a special process: it doesn't get signals it doesn't
 303  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 304  * mistake.
 305  */
 306 void do_signal(struct pt_regs *regs)
 307 {
 308         siginfo_t info;
 309         int signr;
 310         struct k_sigaction ka;
 311         sigset_t *oldset;
 312
 313         /*
 314          * i386 will check if we're coming from kernel mode and bail out
 315          * here.  In my experience this just turns weird crashes into
 316          * weird spin-hangs.  But if we find a case where this seems
 317          * helpful, we can reinstate the check on "!user_mode(regs)".
 318          */
 319
 320         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 321                 oldset = &current->saved_sigmask;
 322         else
 323                 oldset = &current->blocked;
 324
 325         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 326         if (signr > 0) {
 327                 /* Whee! Actually deliver the signal.  */
 328                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 329                         /*
 330                          * A signal was successfully delivered; the saved
 331                          * sigmask will have been stored in the signal frame,
 332                          * and will be restored by sigreturn, so we can simply
 333                          * clear the TS_RESTORE_SIGMASK flag.
 334                          */
 335                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 336                 }
 337
 338                 goto done;
 339         }
 340
 341         /* Did we come from a system call? */
 342         if (regs->faultnum == INT_SWINT_1) {
 343                 /* Restart the system call - no handlers present */
 344                 switch (regs->regs[0]) {
 345                 case -ERESTARTNOHAND:
 346                 case -ERESTARTSYS:
 347                 case -ERESTARTNOINTR:
 348                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 349                         regs->regs[0] = regs->orig_r0;
 350                         regs->pc -= 8;
 351                         break;
 352
 353                 case -ERESTART_RESTARTBLOCK:
 354                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 355                         regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
 356                         regs->pc -= 8;
 357                         break;
 358                 }
 359         }
 360
 361         /* If there's no signal to deliver, just put the saved sigmask back. */
 362         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 363                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 364                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 365         }
 366
 367 done:
 368         /* Avoid double syscall restart if there are nested signals. */
 369         regs->faultnum = INT_SWINT_1_SIGRETURN;
 370 }
 371
 372 int show_unhandled_signals = 1;
 373
 374 static int __init crashinfo(char *str)
 375 {
 376         unsigned long val;
 377         const char *word;
 378
 379         if (*str == '\0')
 380                 val = 2;
 381         else if (*str != '=' || strict_strtoul(++str, 0, &val) != 0)
 382                 return 0;
 383         show_unhandled_signals = val;
 384         switch (show_unhandled_signals) {
 385         case 0:
 386                 word = "No";
 387                 break;
 388         case 1:
 389                 word = "One-line";
 390                 break;
 391         default:
 392                 word = "Detailed";
 393                 break;
 394         }
 395         pr_info("%s crash reports will be generated on the console\n", word);
 396         return 1;
 397 }
 398 __setup("crashinfo", crashinfo);
 399
 400 static void dump_mem(void __user *address)
 401 {
 402         void __user *addr;
 403         enum { region_size = 256, bytes_per_line = 16 };
 404         int i, j, k;
 405         int found_readable_mem = 0;
 406
 407         pr_err("\n");
 408         if (!access_ok(VERIFY_READ, address, 1)) {
 409                 pr_err("Not dumping at address 0x%lx (kernel address)\n",
 410                        (unsigned long)address);
 411                 return;
 412         }
 413
 414         addr = (void __user *)
 415                 (((unsigned long)address & -bytes_per_line) - region_size/2);
 416         if (addr > address)
 417                 addr = NULL;
 418         for (i = 0; i < region_size;
 419              addr += bytes_per_line, i += bytes_per_line) {
 420                 unsigned char buf[bytes_per_line];
 421                 char line[100];
 422                 if (copy_from_user(buf, addr, bytes_per_line))
 423                         continue;
 424                 if (!found_readable_mem) {
 425                         pr_err("Dumping memory around address 0x%lx:\n",
 426                                (unsigned long)address);
 427                         found_readable_mem = 1;
 428                 }
 429                 j = sprintf(line, REGFMT":", (unsigned long)addr);
 430                 for (k = 0; k < bytes_per_line; ++k)
 431                         j += sprintf(&line[j], " %02x", buf[k]);
 432                 pr_err("%s\n", line);
 433         }
 434         if (!found_readable_mem)
 435                 pr_err("No readable memory around address 0x%lx\n",
 436                        (unsigned long)address);
 437 }
 438
 439 void trace_unhandled_signal(const char *type, struct pt_regs *regs,
 440                             unsigned long address, int sig)
 441 {
 442         struct task_struct *tsk = current;
 443
 444         if (show_unhandled_signals == 0)
 445                 return;
 446
 447         /* If the signal is handled, don't show it here. */
 448         if (!is_global_init(tsk)) {
 449                 void __user *handler =
 450                         tsk->sighand->action[sig-1].sa.sa_handler;
 451                 if (handler != SIG_IGN && handler != SIG_DFL)
 452                         return;
 453         }
 454
 455         /* Rate-limit the one-line output, not the detailed output. */
 456         if (show_unhandled_signals <= 1 && !printk_ratelimit())
 457                 return;
 458
 459         printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d",
 460                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 461                tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig);
 462
 463         print_vma_addr(KERN_CONT " in ", regs->pc);
 464
 465         printk(KERN_CONT "\n");
 466
 467         if (show_unhandled_signals > 1) {
 468                 switch (sig) {
 469                 case SIGILL:
 470                 case SIGFPE:
 471                 case SIGSEGV:
 472                 case SIGBUS:
 473                         pr_err("User crash: signal %d,"
 474                                " trap %ld, address 0x%lx\n",
 475                                sig, regs->faultnum, address);
 476                         show_regs(regs);
 477                         dump_mem((void __user *)address);
 478                         break;
 479                 default:
 480                         pr_err("User crash: signal %d, trap %ld\n",
 481                                sig, regs->faultnum);
 482                         break;
 483                 }
 484         }
 485 }