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