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, sigset_t *oldset,
 247                          struct pt_regs *regs)
 248 {
 249         int ret;
 250
 251         /* Are we from a system call? */
 252         if (regs->faultnum == INT_SWINT_1) {
 253                 /* If so, check system call restarting.. */
 254                 switch (regs->regs[0]) {
 255                 case -ERESTART_RESTARTBLOCK:
 256                 case -ERESTARTNOHAND:
 257                         regs->regs[0] = -EINTR;
 258                         break;
 259
 260                 case -ERESTARTSYS:
 261                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 262                                 regs->regs[0] = -EINTR;
 263                                 break;
 264                         }
 265                         /* fallthrough */
 266                 case -ERESTARTNOINTR:
 267                         /* Reload caller-saves to restore r0..r5 and r10. */
 268                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 269                         regs->regs[0] = regs->orig_r0;
 270                         regs->pc -= 8;
 271                 }
 272         }
 273
 274         /* Set up the stack frame */
 275 #ifdef CONFIG_COMPAT
 276         if (is_compat_task())
 277                 ret = compat_setup_rt_frame(sig, ka, info, oldset, regs);
 278         else
 279 #endif
 280                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 281         if (ret == 0) {
 282                 /* This code is only called from system calls or from
 283                  * the work_pending path in the return-to-user code, and
 284                  * either way we can re-enable interrupts unconditionally.
 285                  */
 286                 block_sigmask(ka, sig);
 287         }
 288
 289         return ret;
 290 }
 291
 292 /*
 293  * Note that 'init' is a special process: it doesn't get signals it doesn't
 294  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 295  * mistake.
 296  */
 297 void do_signal(struct pt_regs *regs)
 298 {
 299         siginfo_t info;
 300         int signr;
 301         struct k_sigaction ka;
 302         sigset_t *oldset;
 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         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 312                 oldset = &current->saved_sigmask;
 313         else
 314                 oldset = &current->blocked;
 315
 316         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 317         if (signr > 0) {
 318                 /* Whee! Actually deliver the signal.  */
 319                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 320                         /*
 321                          * A signal was successfully delivered; the saved
 322                          * sigmask will have been stored in the signal frame,
 323                          * and will be restored by sigreturn, so we can simply
 324                          * clear the TS_RESTORE_SIGMASK flag.
 325                          */
 326                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 327                 }
 328
 329                 goto done;
 330         }
 331
 332         /* Did we come from a system call? */
 333         if (regs->faultnum == INT_SWINT_1) {
 334                 /* Restart the system call - no handlers present */
 335                 switch (regs->regs[0]) {
 336                 case -ERESTARTNOHAND:
 337                 case -ERESTARTSYS:
 338                 case -ERESTARTNOINTR:
 339                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 340                         regs->regs[0] = regs->orig_r0;
 341                         regs->pc -= 8;
 342                         break;
 343
 344                 case -ERESTART_RESTARTBLOCK:
 345                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 346                         regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
 347                         regs->pc -= 8;
 348                         break;
 349                 }
 350         }
 351
 352         /* If there's no signal to deliver, just put the saved sigmask back. */
 353         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 354                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 355                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 356         }
 357
 358 done:
 359         /* Avoid double syscall restart if there are nested signals. */
 360         regs->faultnum = INT_SWINT_1_SIGRETURN;
 361 }
 362
 363 int show_unhandled_signals = 1;
 364
 365 static int __init crashinfo(char *str)
 366 {
 367         unsigned long val;
 368         const char *word;
 369
 370         if (*str == '\0')
 371                 val = 2;
 372         else if (*str != '=' || strict_strtoul(++str, 0, &val) != 0)
 373                 return 0;
 374         show_unhandled_signals = val;
 375         switch (show_unhandled_signals) {
 376         case 0:
 377                 word = "No";
 378                 break;
 379         case 1:
 380                 word = "One-line";
 381                 break;
 382         default:
 383                 word = "Detailed";
 384                 break;
 385         }
 386         pr_info("%s crash reports will be generated on the console\n", word);
 387         return 1;
 388 }
 389 __setup("crashinfo", crashinfo);
 390
 391 static void dump_mem(void __user *address)
 392 {
 393         void __user *addr;
 394         enum { region_size = 256, bytes_per_line = 16 };
 395         int i, j, k;
 396         int found_readable_mem = 0;
 397
 398         pr_err("\n");
 399         if (!access_ok(VERIFY_READ, address, 1)) {
 400                 pr_err("Not dumping at address 0x%lx (kernel address)\n",
 401                        (unsigned long)address);
 402                 return;
 403         }
 404
 405         addr = (void __user *)
 406                 (((unsigned long)address & -bytes_per_line) - region_size/2);
 407         if (addr > address)
 408                 addr = NULL;
 409         for (i = 0; i < region_size;
 410              addr += bytes_per_line, i += bytes_per_line) {
 411                 unsigned char buf[bytes_per_line];
 412                 char line[100];
 413                 if (copy_from_user(buf, addr, bytes_per_line))
 414                         continue;
 415                 if (!found_readable_mem) {
 416                         pr_err("Dumping memory around address 0x%lx:\n",
 417                                (unsigned long)address);
 418                         found_readable_mem = 1;
 419                 }
 420                 j = sprintf(line, REGFMT":", (unsigned long)addr);
 421                 for (k = 0; k < bytes_per_line; ++k)
 422                         j += sprintf(&line[j], " %02x", buf[k]);
 423                 pr_err("%s\n", line);
 424         }
 425         if (!found_readable_mem)
 426                 pr_err("No readable memory around address 0x%lx\n",
 427                        (unsigned long)address);
 428 }
 429
 430 void trace_unhandled_signal(const char *type, struct pt_regs *regs,
 431                             unsigned long address, int sig)
 432 {
 433         struct task_struct *tsk = current;
 434
 435         if (show_unhandled_signals == 0)
 436                 return;
 437
 438         /* If the signal is handled, don't show it here. */
 439         if (!is_global_init(tsk)) {
 440                 void __user *handler =
 441                         tsk->sighand->action[sig-1].sa.sa_handler;
 442                 if (handler != SIG_IGN && handler != SIG_DFL)
 443                         return;
 444         }
 445
 446         /* Rate-limit the one-line output, not the detailed output. */
 447         if (show_unhandled_signals <= 1 && !printk_ratelimit())
 448                 return;
 449
 450         printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d",
 451                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 452                tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig);
 453
 454         print_vma_addr(KERN_CONT " in ", regs->pc);
 455
 456         printk(KERN_CONT "\n");
 457
 458         if (show_unhandled_signals > 1) {
 459                 switch (sig) {
 460                 case SIGILL:
 461                 case SIGFPE:
 462                 case SIGSEGV:
 463                 case SIGBUS:
 464                         pr_err("User crash: signal %d,"
 465                                " trap %ld, address 0x%lx\n",
 466                                sig, regs->faultnum, address);
 467                         show_regs(regs);
 468                         dump_mem((void __user *)address);
 469                         break;
 470                 default:
 471                         pr_err("User crash: signal %d, trap %ld\n",
 472                                sig, regs->faultnum);
 473                         break;
 474                 }
 475         }
 476 }