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         set_current_blocked(&set);
 101
 102         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 103                 goto badframe;
 104
 105         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 106                 goto badframe;
 107
 108         return 0;
 109
 110 badframe:
 111         signal_fault("bad sigreturn frame", regs, frame, 0);
 112         return 0;
 113 }
 114
 115 /*
 116  * Set up a signal frame.
 117  */
 118
 119 int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 120 {
 121         int i, err = 0;
 122
 123         for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
 124                 err |= __put_user(regs->regs[i], &sc->gregs[i]);
 125
 126         return err;
 127 }
 128
 129 /*
 130  * Determine which stack to use..
 131  */
 132 static inline void __user *get_sigframe(struct k_sigaction *ka,
 133                                         struct pt_regs *regs,
 134                                         size_t frame_size)
 135 {
 136         unsigned long sp;
 137
 138         /* Default to using normal stack */
 139         sp = regs->sp;
 140
 141         /*
 142          * If we are on the alternate signal stack and would overflow
 143          * it, don't.  Return an always-bogus address instead so we
 144          * will die with SIGSEGV.
 145          */
 146         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 147                 return (void __user __force *)-1UL;
 148
 149         /* This is the X/Open sanctioned signal stack switching.  */
 150         if (ka->sa.sa_flags & SA_ONSTACK) {
 151                 if (sas_ss_flags(sp) == 0)
 152                         sp = current->sas_ss_sp + current->sas_ss_size;
 153         }
 154
 155         sp -= frame_size;
 156         /*
 157          * Align the stack pointer according to the TILE ABI,
 158          * i.e. so that on function entry (sp & 15) == 0.
 159          */
 160         sp &= -16UL;
 161         return (void __user *) sp;
 162 }
 163
 164 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 165                            sigset_t *set, struct pt_regs *regs)
 166 {
 167         unsigned long restorer;
 168         struct rt_sigframe __user *frame;
 169         int err = 0;
 170         int usig;
 171
 172         frame = get_sigframe(ka, regs, sizeof(*frame));
 173
 174         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 175                 goto give_sigsegv;
 176
 177         usig = current_thread_info()->exec_domain
 178                 && current_thread_info()->exec_domain->signal_invmap
 179                 && sig < 32
 180                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 181                 : sig;
 182
 183         /* Always write at least the signal number for the stack backtracer. */
 184         if (ka->sa.sa_flags & SA_SIGINFO) {
 185                 /* At sigreturn time, restore the callee-save registers too. */
 186                 err |= copy_siginfo_to_user(&frame->info, info);
 187                 regs->flags |= PT_FLAGS_RESTORE_REGS;
 188         } else {
 189                 err |= __put_user(info->si_signo, &frame->info.si_signo);
 190         }
 191
 192         /* Create the ucontext.  */
 193         err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
 194         err |= __put_user(0, &frame->uc.uc_flags);
 195         err |= __put_user(NULL, &frame->uc.uc_link);
 196         err |= __put_user((void __user *)(current->sas_ss_sp),
 197                           &frame->uc.uc_stack.ss_sp);
 198         err |= __put_user(sas_ss_flags(regs->sp),
 199                           &frame->uc.uc_stack.ss_flags);
 200         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 201         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 202         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 203         if (err)
 204                 goto give_sigsegv;
 205
 206         restorer = VDSO_BASE;
 207         if (ka->sa.sa_flags & SA_RESTORER)
 208                 restorer = (unsigned long) ka->sa.sa_restorer;
 209
 210         /*
 211          * Set up registers for signal handler.
 212          * Registers that we don't modify keep the value they had from
 213          * user-space at the time we took the signal.
 214          * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
 215          * since some things rely on this (e.g. glibc's debug/segfault.c).
 216          */
 217         regs->pc = (unsigned long) ka->sa.sa_handler;
 218         regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
 219         regs->sp = (unsigned long) frame;
 220         regs->lr = restorer;
 221         regs->regs[0] = (unsigned long) usig;
 222         regs->regs[1] = (unsigned long) &frame->info;
 223         regs->regs[2] = (unsigned long) &frame->uc;
 224         regs->flags |= PT_FLAGS_CALLER_SAVES;
 225
 226         /*
 227          * Notify any tracer that was single-stepping it.
 228          * The tracer may want to single-step inside the
 229          * handler too.
 230          */
 231         if (test_thread_flag(TIF_SINGLESTEP))
 232                 ptrace_notify(SIGTRAP);
 233
 234         return 0;
 235
 236 give_sigsegv:
 237         signal_fault("bad setup frame", regs, frame, sig);
 238         return -EFAULT;
 239 }
 240
 241 /*
 242  * OK, we're invoking a handler
 243  */
 244
 245 static int handle_signal(unsigned long sig, siginfo_t *info,
 246                          struct k_sigaction *ka,
 247                          struct pt_regs *regs)
 248 {
 249         sigset_t *oldset = sigmask_to_save();
 250         int ret;
 251
 252         /* Are we from a system call? */
 253         if (regs->faultnum == INT_SWINT_1) {
 254                 /* If so, check system call restarting.. */
 255                 switch (regs->regs[0]) {
 256                 case -ERESTART_RESTARTBLOCK:
 257                 case -ERESTARTNOHAND:
 258                         regs->regs[0] = -EINTR;
 259                         break;
 260
 261                 case -ERESTARTSYS:
 262                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 263                                 regs->regs[0] = -EINTR;
 264                                 break;
 265                         }
 266                         /* fallthrough */
 267                 case -ERESTARTNOINTR:
 268                         /* Reload caller-saves to restore r0..r5 and r10. */
 269                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 270                         regs->regs[0] = regs->orig_r0;
 271                         regs->pc -= 8;
 272                 }
 273         }
 274
 275         /* Set up the stack frame */
 276 #ifdef CONFIG_COMPAT
 277         if (is_compat_task())
 278                 ret = compat_setup_rt_frame(sig, ka, info, oldset, regs);
 279         else
 280 #endif
 281                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 282         if (ret == 0) {
 283                 /* This code is only called from system calls or from
 284                  * the work_pending path in the return-to-user code, and
 285                  * either way we can re-enable interrupts unconditionally.
 286                  */
 287                 block_sigmask(ka, sig);
 288         }
 289
 290         return ret;
 291 }
 292
 293 /*
 294  * Note that 'init' is a special process: it doesn't get signals it doesn't
 295  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 296  * mistake.
 297  */
 298 void do_signal(struct pt_regs *regs)
 299 {
 300         siginfo_t info;
 301         int signr;
 302         struct k_sigaction ka;
 303
 304         /*
 305          * i386 will check if we're coming from kernel mode and bail out
 306          * here.  In my experience this just turns weird crashes into
 307          * weird spin-hangs.  But if we find a case where this seems
 308          * helpful, we can reinstate the check on "!user_mode(regs)".
 309          */
 310
 311         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 312         if (signr > 0) {
 313                 /* Whee! Actually deliver the signal.  */
 314                 if (handle_signal(signr, &info, &ka, regs) == 0) {
 315                         /*
 316                          * A signal was successfully delivered; the saved
 317                          * sigmask will have been stored in the signal frame,
 318                          * and will be restored by sigreturn, so we can simply
 319                          * clear the TS_RESTORE_SIGMASK flag.
 320                          */
 321                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 322                 }
 323
 324                 goto done;
 325         }
 326
 327         /* Did we come from a system call? */
 328         if (regs->faultnum == INT_SWINT_1) {
 329                 /* Restart the system call - no handlers present */
 330                 switch (regs->regs[0]) {
 331                 case -ERESTARTNOHAND:
 332                 case -ERESTARTSYS:
 333                 case -ERESTARTNOINTR:
 334                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 335                         regs->regs[0] = regs->orig_r0;
 336                         regs->pc -= 8;
 337                         break;
 338
 339                 case -ERESTART_RESTARTBLOCK:
 340                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 341                         regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
 342                         regs->pc -= 8;
 343                         break;
 344                 }
 345         }
 346
 347         /* If there's no signal to deliver, just put the saved sigmask back. */
 348         restore_saved_sigmask();
 349
 350 done:
 351         /* Avoid double syscall restart if there are nested signals. */
 352         regs->faultnum = INT_SWINT_1_SIGRETURN;
 353 }
 354
 355 int show_unhandled_signals = 1;
 356
 357 static int __init crashinfo(char *str)
 358 {
 359         unsigned long val;
 360         const char *word;
 361
 362         if (*str == '\0')
 363                 val = 2;
 364         else if (*str != '=' || strict_strtoul(++str, 0, &val) != 0)
 365                 return 0;
 366         show_unhandled_signals = val;
 367         switch (show_unhandled_signals) {
 368         case 0:
 369                 word = "No";
 370                 break;
 371         case 1:
 372                 word = "One-line";
 373                 break;
 374         default:
 375                 word = "Detailed";
 376                 break;
 377         }
 378         pr_info("%s crash reports will be generated on the console\n", word);
 379         return 1;
 380 }
 381 __setup("crashinfo", crashinfo);
 382
 383 static void dump_mem(void __user *address)
 384 {
 385         void __user *addr;
 386         enum { region_size = 256, bytes_per_line = 16 };
 387         int i, j, k;
 388         int found_readable_mem = 0;
 389
 390         pr_err("\n");
 391         if (!access_ok(VERIFY_READ, address, 1)) {
 392                 pr_err("Not dumping at address 0x%lx (kernel address)\n",
 393                        (unsigned long)address);
 394                 return;
 395         }
 396
 397         addr = (void __user *)
 398                 (((unsigned long)address & -bytes_per_line) - region_size/2);
 399         if (addr > address)
 400                 addr = NULL;
 401         for (i = 0; i < region_size;
 402              addr += bytes_per_line, i += bytes_per_line) {
 403                 unsigned char buf[bytes_per_line];
 404                 char line[100];
 405                 if (copy_from_user(buf, addr, bytes_per_line))
 406                         continue;
 407                 if (!found_readable_mem) {
 408                         pr_err("Dumping memory around address 0x%lx:\n",
 409                                (unsigned long)address);
 410                         found_readable_mem = 1;
 411                 }
 412                 j = sprintf(line, REGFMT":", (unsigned long)addr);
 413                 for (k = 0; k < bytes_per_line; ++k)
 414                         j += sprintf(&line[j], " %02x", buf[k]);
 415                 pr_err("%s\n", line);
 416         }
 417         if (!found_readable_mem)
 418                 pr_err("No readable memory around address 0x%lx\n",
 419                        (unsigned long)address);
 420 }
 421
 422 void trace_unhandled_signal(const char *type, struct pt_regs *regs,
 423                             unsigned long address, int sig)
 424 {
 425         struct task_struct *tsk = current;
 426
 427         if (show_unhandled_signals == 0)
 428                 return;
 429
 430         /* If the signal is handled, don't show it here. */
 431         if (!is_global_init(tsk)) {
 432                 void __user *handler =
 433                         tsk->sighand->action[sig-1].sa.sa_handler;
 434                 if (handler != SIG_IGN && handler != SIG_DFL)
 435                         return;
 436         }
 437
 438         /* Rate-limit the one-line output, not the detailed output. */
 439         if (show_unhandled_signals <= 1 && !printk_ratelimit())
 440                 return;
 441
 442         printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d",
 443                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 444                tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig);
 445
 446         print_vma_addr(KERN_CONT " in ", regs->pc);
 447
 448         printk(KERN_CONT "\n");
 449
 450         if (show_unhandled_signals > 1) {
 451                 switch (sig) {
 452                 case SIGILL:
 453                 case SIGFPE:
 454                 case SIGSEGV:
 455                 case SIGBUS:
 456                         pr_err("User crash: signal %d,"
 457                                " trap %ld, address 0x%lx\n",
 458                                sig, regs->faultnum, address);
 459                         show_regs(regs);
 460                         dump_mem((void __user *)address);
 461                         break;
 462                 default:
 463                         pr_err("User crash: signal %d, trap %ld\n",
 464                                sig, regs->faultnum);
 465                         break;
 466                 }
 467         }
 468 }