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 <asm/vdso.h>
  37 #include <arch/interrupts.h>
  38
  39 #define DEBUG_SIG 0
  40
  41 /*
  42  * Do a signal return; undo the signal stack.
  43  */
  44
  45 int restore_sigcontext(struct pt_regs *regs,
  46                        struct sigcontext __user *sc)
  47 {
  48         int err;
  49
  50         /* Always make any pending restarted system calls return -EINTR */
  51         current->restart_block.fn = do_no_restart_syscall;
  52
  53         /*
  54          * Enforce that sigcontext is like pt_regs, and doesn't mess
  55          * up our stack alignment rules.
  56          */
  57         BUILD_BUG_ON(sizeof(struct sigcontext) != sizeof(struct pt_regs));
  58         BUILD_BUG_ON(sizeof(struct sigcontext) % 8 != 0);
  59         err = __copy_from_user(regs, sc, sizeof(*regs));
  60
  61         /* Ensure that the PL is always set to USER_PL. */
  62         regs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(regs->ex1));
  63
  64         regs->faultnum = INT_SWINT_1_SIGRETURN;
  65
  66         return err;
  67 }
  68
  69 void signal_fault(const char *type, struct pt_regs *regs,
  70                   void __user *frame, int sig)
  71 {
  72         trace_unhandled_signal(type, regs, (unsigned long)frame, SIGSEGV);
  73         force_sigsegv(sig, current);
  74 }
  75
  76 /* The assembly shim for this function arranges to ignore the return value. */
  77 SYSCALL_DEFINE0(rt_sigreturn)
  78 {
  79         struct pt_regs *regs = current_pt_regs();
  80         struct rt_sigframe __user *frame =
  81                 (struct rt_sigframe __user *)(regs->sp);
  82         sigset_t set;
  83
  84         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  85                 goto badframe;
  86         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  87                 goto badframe;
  88
  89         set_current_blocked(&set);
  90
  91         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  92                 goto badframe;
  93
  94         if (restore_altstack(&frame->uc.uc_stack))
  95                 goto badframe;
  96
  97         return 0;
  98
  99 badframe:
 100         signal_fault("bad sigreturn frame", regs, frame, 0);
 101         return 0;
 102 }
 103
 104 /*
 105  * Set up a signal frame.
 106  */
 107
 108 int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 109 {
 110         return  __copy_to_user(sc, regs, sizeof(*regs));
 111 }
 112
 113 /*
 114  * Determine which stack to use..
 115  */
 116 static inline void __user *get_sigframe(struct k_sigaction *ka,
 117                                         struct pt_regs *regs,
 118                                         size_t frame_size)
 119 {
 120         unsigned long sp;
 121
 122         /* Default to using normal stack */
 123         sp = regs->sp;
 124
 125         /*
 126          * If we are on the alternate signal stack and would overflow
 127          * it, don't.  Return an always-bogus address instead so we
 128          * will die with SIGSEGV.
 129          */
 130         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 131                 return (void __user __force *)-1UL;
 132
 133         /* This is the X/Open sanctioned signal stack switching.  */
 134         if (ka->sa.sa_flags & SA_ONSTACK) {
 135                 if (sas_ss_flags(sp) == 0)
 136                         sp = current->sas_ss_sp + current->sas_ss_size;
 137         }
 138
 139         sp -= frame_size;
 140         /*
 141          * Align the stack pointer according to the TILE ABI,
 142          * i.e. so that on function entry (sp & 15) == 0.
 143          */
 144         sp &= -16UL;
 145         return (void __user *) sp;
 146 }
 147
 148 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 149                           struct pt_regs *regs)
 150 {
 151         unsigned long restorer;
 152         struct rt_sigframe __user *frame;
 153         int err = 0, sig = ksig->sig;
 154
 155         frame = get_sigframe(&ksig->ka, regs, sizeof(*frame));
 156
 157         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 158                 goto err;
 159
 160         /* Always write at least the signal number for the stack backtracer. */
 161         if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 162                 /* At sigreturn time, restore the callee-save registers too. */
 163                 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 164                 regs->flags |= PT_FLAGS_RESTORE_REGS;
 165         } else {
 166                 err |= __put_user(ksig->info.si_signo, &frame->info.si_signo);
 167         }
 168
 169         /* Create the ucontext.  */
 170         err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
 171         err |= __put_user(0, &frame->uc.uc_flags);
 172         err |= __put_user(NULL, &frame->uc.uc_link);
 173         err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 174         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 175         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 176         if (err)
 177                 goto err;
 178
 179         restorer = VDSO_SYM(&__vdso_rt_sigreturn);
 180         if (ksig->ka.sa.sa_flags & SA_RESTORER)
 181                 restorer = (unsigned long) ksig->ka.sa.sa_restorer;
 182
 183         /*
 184          * Set up registers for signal handler.
 185          * Registers that we don't modify keep the value they had from
 186          * user-space at the time we took the signal.
 187          * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
 188          * since some things rely on this (e.g. glibc's debug/segfault.c).
 189          */
 190         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 191         regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
 192         regs->sp = (unsigned long) frame;
 193         regs->lr = restorer;
 194         regs->regs[0] = (unsigned long) sig;
 195         regs->regs[1] = (unsigned long) &frame->info;
 196         regs->regs[2] = (unsigned long) &frame->uc;
 197         regs->flags |= PT_FLAGS_CALLER_SAVES;
 198         return 0;
 199
 200 err:
 201         trace_unhandled_signal("bad sigreturn frame", regs,
 202                               (unsigned long)frame, SIGSEGV);
 203         return -EFAULT;
 204 }
 205
 206 /*
 207  * OK, we're invoking a handler
 208  */
 209
 210 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 211 {
 212         sigset_t *oldset = sigmask_to_save();
 213         int ret;
 214
 215         /* Are we from a system call? */
 216         if (regs->faultnum == INT_SWINT_1) {
 217                 /* If so, check system call restarting.. */
 218                 switch (regs->regs[0]) {
 219                 case -ERESTART_RESTARTBLOCK:
 220                 case -ERESTARTNOHAND:
 221                         regs->regs[0] = -EINTR;
 222                         break;
 223
 224                 case -ERESTARTSYS:
 225                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 226                                 regs->regs[0] = -EINTR;
 227                                 break;
 228                         }
 229                         /* fallthrough */
 230                 case -ERESTARTNOINTR:
 231                         /* Reload caller-saves to restore r0..r5 and r10. */
 232                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 233                         regs->regs[0] = regs->orig_r0;
 234                         regs->pc -= 8;
 235                 }
 236         }
 237
 238         /* Set up the stack frame */
 239 #ifdef CONFIG_COMPAT
 240         if (is_compat_task())
 241                 ret = compat_setup_rt_frame(ksig, oldset, regs);
 242         else
 243 #endif
 244                 ret = setup_rt_frame(ksig, oldset, regs);
 245
 246         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 247 }
 248
 249 /*
 250  * Note that 'init' is a special process: it doesn't get signals it doesn't
 251  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 252  * mistake.
 253  */
 254 void do_signal(struct pt_regs *regs)
 255 {
 256         struct ksignal ksig;
 257
 258         /*
 259          * i386 will check if we're coming from kernel mode and bail out
 260          * here.  In my experience this just turns weird crashes into
 261          * weird spin-hangs.  But if we find a case where this seems
 262          * helpful, we can reinstate the check on "!user_mode(regs)".
 263          */
 264
 265         if (get_signal(&ksig)) {
 266                 /* Whee! Actually deliver the signal.  */
 267                 handle_signal(&ksig, regs);
 268                 goto done;
 269         }
 270
 271         /* Did we come from a system call? */
 272         if (regs->faultnum == INT_SWINT_1) {
 273                 /* Restart the system call - no handlers present */
 274                 switch (regs->regs[0]) {
 275                 case -ERESTARTNOHAND:
 276                 case -ERESTARTSYS:
 277                 case -ERESTARTNOINTR:
 278                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 279                         regs->regs[0] = regs->orig_r0;
 280                         regs->pc -= 8;
 281                         break;
 282
 283                 case -ERESTART_RESTARTBLOCK:
 284                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 285                         regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
 286                         regs->pc -= 8;
 287                         break;
 288                 }
 289         }
 290
 291         /* If there's no signal to deliver, just put the saved sigmask back. */
 292         restore_saved_sigmask();
 293
 294 done:
 295         /* Avoid double syscall restart if there are nested signals. */
 296         regs->faultnum = INT_SWINT_1_SIGRETURN;
 297 }
 298
 299 int show_unhandled_signals = 1;
 300
 301 static int __init crashinfo(char *str)
 302 {
 303         const char *word;
 304
 305         if (*str == '\0')
 306                 show_unhandled_signals = 2;
 307         else if (*str != '=' || kstrtoint(++str, 0, &show_unhandled_signals) != 0)
 308                 return 0;
 309
 310         switch (show_unhandled_signals) {
 311         case 0:
 312                 word = "No";
 313                 break;
 314         case 1:
 315                 word = "One-line";
 316                 break;
 317         default:
 318                 word = "Detailed";
 319                 break;
 320         }
 321         pr_info("%s crash reports will be generated on the console\n", word);
 322         return 1;
 323 }
 324 __setup("crashinfo", crashinfo);
 325
 326 static void dump_mem(void __user *address)
 327 {
 328         void __user *addr;
 329         enum { region_size = 256, bytes_per_line = 16 };
 330         int i, j, k;
 331         int found_readable_mem = 0;
 332
 333         if (!access_ok(VERIFY_READ, address, 1)) {
 334                 pr_err("Not dumping at address 0x%lx (kernel address)\n",
 335                        (unsigned long)address);
 336                 return;
 337         }
 338
 339         addr = (void __user *)
 340                 (((unsigned long)address & -bytes_per_line) - region_size/2);
 341         if (addr > address)
 342                 addr = NULL;
 343         for (i = 0; i < region_size;
 344              addr += bytes_per_line, i += bytes_per_line) {
 345                 unsigned char buf[bytes_per_line];
 346                 char line[100];
 347                 if (copy_from_user(buf, addr, bytes_per_line))
 348                         continue;
 349                 if (!found_readable_mem) {
 350                         pr_err("Dumping memory around address 0x%lx:\n",
 351                                (unsigned long)address);
 352                         found_readable_mem = 1;
 353                 }
 354                 j = sprintf(line, REGFMT ":", (unsigned long)addr);
 355                 for (k = 0; k < bytes_per_line; ++k)
 356                         j += sprintf(&line[j], " %02x", buf[k]);
 357                 pr_err("%s\n", line);
 358         }
 359         if (!found_readable_mem)
 360                 pr_err("No readable memory around address 0x%lx\n",
 361                        (unsigned long)address);
 362 }
 363
 364 void trace_unhandled_signal(const char *type, struct pt_regs *regs,
 365                             unsigned long address, int sig)
 366 {
 367         struct task_struct *tsk = current;
 368
 369         if (show_unhandled_signals == 0)
 370                 return;
 371
 372         /* If the signal is handled, don't show it here. */
 373         if (!is_global_init(tsk)) {
 374                 void __user *handler =
 375                         tsk->sighand->action[sig-1].sa.sa_handler;
 376                 if (handler != SIG_IGN && handler != SIG_DFL)
 377                         return;
 378         }
 379
 380         /* Rate-limit the one-line output, not the detailed output. */
 381         if (show_unhandled_signals <= 1 && !printk_ratelimit())
 382                 return;
 383
 384         printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d",
 385                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 386                tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig);
 387
 388         print_vma_addr(KERN_CONT " in ", regs->pc);
 389
 390         printk(KERN_CONT "\n");
 391
 392         if (show_unhandled_signals > 1) {
 393                 switch (sig) {
 394                 case SIGILL:
 395                 case SIGFPE:
 396                 case SIGSEGV:
 397                 case SIGBUS:
 398                         pr_err("User crash: signal %d, trap %ld, address 0x%lx\n",
 399                                sig, regs->faultnum, address);
 400                         show_regs(regs);
 401                         dump_mem((void __user *)address);
 402                         break;
 403                 default:
 404                         pr_err("User crash: signal %d, trap %ld\n",
 405                                sig, regs->faultnum);
 406                         break;
 407                 }
 408         }
 409 }