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_DEFINE2(sigaltstack, const stack_t __user *, uss,
  41                 stack_t __user *, uoss)
  42 {
  43         return do_sigaltstack(uss, uoss, current_pt_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_DEFINE0(rt_sigreturn)
  87 {
  88         struct pt_regs *regs = current_pt_regs();
  89         struct rt_sigframe __user *frame =
  90                 (struct rt_sigframe __user *)(regs->sp);
  91         sigset_t set;
  92
  93         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  94                 goto badframe;
  95         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  96                 goto badframe;
  97
  98         set_current_blocked(&set);
  99
 100         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 101                 goto badframe;
 102
 103         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 104                 goto badframe;
 105
 106         return 0;
 107
 108 badframe:
 109         signal_fault("bad sigreturn frame", regs, frame, 0);
 110         return 0;
 111 }
 112
 113 /*
 114  * Set up a signal frame.
 115  */
 116
 117 int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 118 {
 119         int i, err = 0;
 120
 121         for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
 122                 err |= __put_user(regs->regs[i], &sc->gregs[i]);
 123
 124         return err;
 125 }
 126
 127 /*
 128  * Determine which stack to use..
 129  */
 130 static inline void __user *get_sigframe(struct k_sigaction *ka,
 131                                         struct pt_regs *regs,
 132                                         size_t frame_size)
 133 {
 134         unsigned long sp;
 135
 136         /* Default to using normal stack */
 137         sp = regs->sp;
 138
 139         /*
 140          * If we are on the alternate signal stack and would overflow
 141          * it, don't.  Return an always-bogus address instead so we
 142          * will die with SIGSEGV.
 143          */
 144         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 145                 return (void __user __force *)-1UL;
 146
 147         /* This is the X/Open sanctioned signal stack switching.  */
 148         if (ka->sa.sa_flags & SA_ONSTACK) {
 149                 if (sas_ss_flags(sp) == 0)
 150                         sp = current->sas_ss_sp + current->sas_ss_size;
 151         }
 152
 153         sp -= frame_size;
 154         /*
 155          * Align the stack pointer according to the TILE ABI,
 156          * i.e. so that on function entry (sp & 15) == 0.
 157          */
 158         sp &= -16UL;
 159         return (void __user *) sp;
 160 }
 161
 162 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 163                            sigset_t *set, struct pt_regs *regs)
 164 {
 165         unsigned long restorer;
 166         struct rt_sigframe __user *frame;
 167         int err = 0;
 168         int usig;
 169
 170         frame = get_sigframe(ka, regs, sizeof(*frame));
 171
 172         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 173                 goto give_sigsegv;
 174
 175         usig = current_thread_info()->exec_domain
 176                 && current_thread_info()->exec_domain->signal_invmap
 177                 && sig < 32
 178                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 179                 : sig;
 180
 181         /* Always write at least the signal number for the stack backtracer. */
 182         if (ka->sa.sa_flags & SA_SIGINFO) {
 183                 /* At sigreturn time, restore the callee-save registers too. */
 184                 err |= copy_siginfo_to_user(&frame->info, info);
 185                 regs->flags |= PT_FLAGS_RESTORE_REGS;
 186         } else {
 187                 err |= __put_user(info->si_signo, &frame->info.si_signo);
 188         }
 189
 190         /* Create the ucontext.  */
 191         err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
 192         err |= __put_user(0, &frame->uc.uc_flags);
 193         err |= __put_user(NULL, &frame->uc.uc_link);
 194         err |= __put_user((void __user *)(current->sas_ss_sp),
 195                           &frame->uc.uc_stack.ss_sp);
 196         err |= __put_user(sas_ss_flags(regs->sp),
 197                           &frame->uc.uc_stack.ss_flags);
 198         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 199         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 200         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 201         if (err)
 202                 goto give_sigsegv;
 203
 204         restorer = VDSO_BASE;
 205         if (ka->sa.sa_flags & SA_RESTORER)
 206                 restorer = (unsigned long) ka->sa.sa_restorer;
 207
 208         /*
 209          * Set up registers for signal handler.
 210          * Registers that we don't modify keep the value they had from
 211          * user-space at the time we took the signal.
 212          * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
 213          * since some things rely on this (e.g. glibc's debug/segfault.c).
 214          */
 215         regs->pc = (unsigned long) ka->sa.sa_handler;
 216         regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
 217         regs->sp = (unsigned long) frame;
 218         regs->lr = restorer;
 219         regs->regs[0] = (unsigned long) usig;
 220         regs->regs[1] = (unsigned long) &frame->info;
 221         regs->regs[2] = (unsigned long) &frame->uc;
 222         regs->flags |= PT_FLAGS_CALLER_SAVES;
 223         return 0;
 224
 225 give_sigsegv:
 226         signal_fault("bad setup frame", regs, frame, sig);
 227         return -EFAULT;
 228 }
 229
 230 /*
 231  * OK, we're invoking a handler
 232  */
 233
 234 static void handle_signal(unsigned long sig, siginfo_t *info,
 235                          struct k_sigaction *ka,
 236                          struct pt_regs *regs)
 237 {
 238         sigset_t *oldset = sigmask_to_save();
 239         int ret;
 240
 241         /* Are we from a system call? */
 242         if (regs->faultnum == INT_SWINT_1) {
 243                 /* If so, check system call restarting.. */
 244                 switch (regs->regs[0]) {
 245                 case -ERESTART_RESTARTBLOCK:
 246                 case -ERESTARTNOHAND:
 247                         regs->regs[0] = -EINTR;
 248                         break;
 249
 250                 case -ERESTARTSYS:
 251                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 252                                 regs->regs[0] = -EINTR;
 253                                 break;
 254                         }
 255                         /* fallthrough */
 256                 case -ERESTARTNOINTR:
 257                         /* Reload caller-saves to restore r0..r5 and r10. */
 258                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 259                         regs->regs[0] = regs->orig_r0;
 260                         regs->pc -= 8;
 261                 }
 262         }
 263
 264         /* Set up the stack frame */
 265 #ifdef CONFIG_COMPAT
 266         if (is_compat_task())
 267                 ret = compat_setup_rt_frame(sig, ka, info, oldset, regs);
 268         else
 269 #endif
 270                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 271         if (ret)
 272                 return;
 273         signal_delivered(sig, info, ka, regs,
 274                         test_thread_flag(TIF_SINGLESTEP));
 275 }
 276
 277 /*
 278  * Note that 'init' is a special process: it doesn't get signals it doesn't
 279  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 280  * mistake.
 281  */
 282 void do_signal(struct pt_regs *regs)
 283 {
 284         siginfo_t info;
 285         int signr;
 286         struct k_sigaction ka;
 287
 288         /*
 289          * i386 will check if we're coming from kernel mode and bail out
 290          * here.  In my experience this just turns weird crashes into
 291          * weird spin-hangs.  But if we find a case where this seems
 292          * helpful, we can reinstate the check on "!user_mode(regs)".
 293          */
 294
 295         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 296         if (signr > 0) {
 297                 /* Whee! Actually deliver the signal.  */
 298                 handle_signal(signr, &info, &ka, regs);
 299                 goto done;
 300         }
 301
 302         /* Did we come from a system call? */
 303         if (regs->faultnum == INT_SWINT_1) {
 304                 /* Restart the system call - no handlers present */
 305                 switch (regs->regs[0]) {
 306                 case -ERESTARTNOHAND:
 307                 case -ERESTARTSYS:
 308                 case -ERESTARTNOINTR:
 309                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 310                         regs->regs[0] = regs->orig_r0;
 311                         regs->pc -= 8;
 312                         break;
 313
 314                 case -ERESTART_RESTARTBLOCK:
 315                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 316                         regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
 317                         regs->pc -= 8;
 318                         break;
 319                 }
 320         }
 321
 322         /* If there's no signal to deliver, just put the saved sigmask back. */
 323         restore_saved_sigmask();
 324
 325 done:
 326         /* Avoid double syscall restart if there are nested signals. */
 327         regs->faultnum = INT_SWINT_1_SIGRETURN;
 328 }
 329
 330 int show_unhandled_signals = 1;
 331
 332 static int __init crashinfo(char *str)
 333 {
 334         unsigned long val;
 335         const char *word;
 336
 337         if (*str == '\0')
 338                 val = 2;
 339         else if (*str != '=' || strict_strtoul(++str, 0, &val) != 0)
 340                 return 0;
 341         show_unhandled_signals = val;
 342         switch (show_unhandled_signals) {
 343         case 0:
 344                 word = "No";
 345                 break;
 346         case 1:
 347                 word = "One-line";
 348                 break;
 349         default:
 350                 word = "Detailed";
 351                 break;
 352         }
 353         pr_info("%s crash reports will be generated on the console\n", word);
 354         return 1;
 355 }
 356 __setup("crashinfo", crashinfo);
 357
 358 static void dump_mem(void __user *address)
 359 {
 360         void __user *addr;
 361         enum { region_size = 256, bytes_per_line = 16 };
 362         int i, j, k;
 363         int found_readable_mem = 0;
 364
 365         pr_err("\n");
 366         if (!access_ok(VERIFY_READ, address, 1)) {
 367                 pr_err("Not dumping at address 0x%lx (kernel address)\n",
 368                        (unsigned long)address);
 369                 return;
 370         }
 371
 372         addr = (void __user *)
 373                 (((unsigned long)address & -bytes_per_line) - region_size/2);
 374         if (addr > address)
 375                 addr = NULL;
 376         for (i = 0; i < region_size;
 377              addr += bytes_per_line, i += bytes_per_line) {
 378                 unsigned char buf[bytes_per_line];
 379                 char line[100];
 380                 if (copy_from_user(buf, addr, bytes_per_line))
 381                         continue;
 382                 if (!found_readable_mem) {
 383                         pr_err("Dumping memory around address 0x%lx:\n",
 384                                (unsigned long)address);
 385                         found_readable_mem = 1;
 386                 }
 387                 j = sprintf(line, REGFMT":", (unsigned long)addr);
 388                 for (k = 0; k < bytes_per_line; ++k)
 389                         j += sprintf(&line[j], " %02x", buf[k]);
 390                 pr_err("%s\n", line);
 391         }
 392         if (!found_readable_mem)
 393                 pr_err("No readable memory around address 0x%lx\n",
 394                        (unsigned long)address);
 395 }
 396
 397 void trace_unhandled_signal(const char *type, struct pt_regs *regs,
 398                             unsigned long address, int sig)
 399 {
 400         struct task_struct *tsk = current;
 401
 402         if (show_unhandled_signals == 0)
 403                 return;
 404
 405         /* If the signal is handled, don't show it here. */
 406         if (!is_global_init(tsk)) {
 407                 void __user *handler =
 408                         tsk->sighand->action[sig-1].sa.sa_handler;
 409                 if (handler != SIG_IGN && handler != SIG_DFL)
 410                         return;
 411         }
 412
 413         /* Rate-limit the one-line output, not the detailed output. */
 414         if (show_unhandled_signals <= 1 && !printk_ratelimit())
 415                 return;
 416
 417         printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d",
 418                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 419                tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig);
 420
 421         print_vma_addr(KERN_CONT " in ", regs->pc);
 422
 423         printk(KERN_CONT "\n");
 424
 425         if (show_unhandled_signals > 1) {
 426                 switch (sig) {
 427                 case SIGILL:
 428                 case SIGFPE:
 429                 case SIGSEGV:
 430                 case SIGBUS:
 431                         pr_err("User crash: signal %d,"
 432                                " trap %ld, address 0x%lx\n",
 433                                sig, regs->faultnum, address);
 434                         show_regs(regs);
 435                         dump_mem((void __user *)address);
 436                         break;
 437                 default:
 438                         pr_err("User crash: signal %d, trap %ld\n",
 439                                sig, regs->faultnum);
 440                         break;
 441                 }
 442         }
 443 }