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/sched/debug.h>
  18 #include <linux/sched/task_stack.h>
  19 #include <linux/mm.h>
  20 #include <linux/smp.h>
  21 #include <linux/kernel.h>
  22 #include <linux/signal.h>
  23 #include <linux/errno.h>
  24 #include <linux/wait.h>
  25 #include <linux/unistd.h>
  26 #include <linux/stddef.h>
  27 #include <linux/personality.h>
  28 #include <linux/suspend.h>
  29 #include <linux/ptrace.h>
  30 #include <linux/elf.h>
  31 #include <linux/compat.h>
  32 #include <linux/syscalls.h>
  33 #include <linux/uaccess.h>
  34 #include <asm/processor.h>
  35 #include <asm/ucontext.h>
  36 #include <asm/sigframe.h>
  37 #include <asm/syscalls.h>
  38 #include <asm/vdso.h>
  39 #include <arch/interrupts.h>
  40
  41 #define DEBUG_SIG 0
  42
  43 /*
  44  * Do a signal return; undo the signal stack.
  45  */
  46
  47 int restore_sigcontext(struct pt_regs *regs,
  48                        struct sigcontext __user *sc)
  49 {
  50         int err;
  51
  52         /* Always make any pending restarted system calls return -EINTR */
  53         current->restart_block.fn = do_no_restart_syscall;
  54
  55         /*
  56          * Enforce that sigcontext is like pt_regs, and doesn't mess
  57          * up our stack alignment rules.
  58          */
  59         BUILD_BUG_ON(sizeof(struct sigcontext) != sizeof(struct pt_regs));
  60         BUILD_BUG_ON(sizeof(struct sigcontext) % 8 != 0);
  61         err = __copy_from_user(regs, sc, sizeof(*regs));
  62
  63         /* Ensure that the PL is always set to USER_PL. */
  64         regs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(regs->ex1));
  65
  66         regs->faultnum = INT_SWINT_1_SIGRETURN;
  67
  68         return err;
  69 }
  70
  71 void signal_fault(const char *type, struct pt_regs *regs,
  72                   void __user *frame, int sig)
  73 {
  74         trace_unhandled_signal(type, regs, (unsigned long)frame, SIGSEGV);
  75         force_sigsegv(sig, current);
  76 }
  77
  78 /* The assembly shim for this function arranges to ignore the return value. */
  79 SYSCALL_DEFINE0(rt_sigreturn)
  80 {
  81         struct pt_regs *regs = current_pt_regs();
  82         struct rt_sigframe __user *frame =
  83                 (struct rt_sigframe __user *)(regs->sp);
  84         sigset_t set;
  85
  86         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  87                 goto badframe;
  88         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  89                 goto badframe;
  90
  91         set_current_blocked(&set);
  92
  93         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  94                 goto badframe;
  95
  96         if (restore_altstack(&frame->uc.uc_stack))
  97                 goto badframe;
  98
  99         return 0;
 100
 101 badframe:
 102         signal_fault("bad sigreturn frame", regs, frame, 0);
 103         return 0;
 104 }
 105
 106 /*
 107  * Set up a signal frame.
 108  */
 109
 110 int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 111 {
 112         return  __copy_to_user(sc, regs, sizeof(*regs));
 113 }
 114
 115 /*
 116  * Determine which stack to use..
 117  */
 118 static inline void __user *get_sigframe(struct k_sigaction *ka,
 119                                         struct pt_regs *regs,
 120                                         size_t frame_size)
 121 {
 122         unsigned long sp;
 123
 124         /* Default to using normal stack */
 125         sp = regs->sp;
 126
 127         /*
 128          * If we are on the alternate signal stack and would overflow
 129          * it, don't.  Return an always-bogus address instead so we
 130          * will die with SIGSEGV.
 131          */
 132         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 133                 return (void __user __force *)-1UL;
 134
 135         /* This is the X/Open sanctioned signal stack switching.  */
 136         if (ka->sa.sa_flags & SA_ONSTACK) {
 137                 if (sas_ss_flags(sp) == 0)
 138                         sp = current->sas_ss_sp + current->sas_ss_size;
 139         }
 140
 141         sp -= frame_size;
 142         /*
 143          * Align the stack pointer according to the TILE ABI,
 144          * i.e. so that on function entry (sp & 15) == 0.
 145          */
 146         sp &= -16UL;
 147         return (void __user *) sp;
 148 }
 149
 150 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 151                           struct pt_regs *regs)
 152 {
 153         unsigned long restorer;
 154         struct rt_sigframe __user *frame;
 155         int err = 0, sig = ksig->sig;
 156
 157         frame = get_sigframe(&ksig->ka, regs, sizeof(*frame));
 158
 159         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 160                 goto err;
 161
 162         /* Always write at least the signal number for the stack backtracer. */
 163         if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 164                 /* At sigreturn time, restore the callee-save registers too. */
 165                 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 166                 regs->flags |= PT_FLAGS_RESTORE_REGS;
 167         } else {
 168                 err |= __put_user(ksig->info.si_signo, &frame->info.si_signo);
 169         }
 170
 171         /* Create the ucontext.  */
 172         err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
 173         err |= __put_user(0, &frame->uc.uc_flags);
 174         err |= __put_user(NULL, &frame->uc.uc_link);
 175         err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 176         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 177         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 178         if (err)
 179                 goto err;
 180
 181         restorer = VDSO_SYM(&__vdso_rt_sigreturn);
 182         if (ksig->ka.sa.sa_flags & SA_RESTORER)
 183                 restorer = (unsigned long) ksig->ka.sa.sa_restorer;
 184
 185         /*
 186          * Set up registers for signal handler.
 187          * Registers that we don't modify keep the value they had from
 188          * user-space at the time we took the signal.
 189          * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
 190          * since some things rely on this (e.g. glibc's debug/segfault.c).
 191          */
 192         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 193         regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
 194         regs->sp = (unsigned long) frame;
 195         regs->lr = restorer;
 196         regs->regs[0] = (unsigned long) sig;
 197         regs->regs[1] = (unsigned long) &frame->info;
 198         regs->regs[2] = (unsigned long) &frame->uc;
 199         regs->flags |= PT_FLAGS_CALLER_SAVES;
 200         return 0;
 201
 202 err:
 203         trace_unhandled_signal("bad sigreturn frame", regs,
 204                               (unsigned long)frame, SIGSEGV);
 205         return -EFAULT;
 206 }
 207
 208 /*
 209  * OK, we're invoking a handler
 210  */
 211
 212 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 213 {
 214         sigset_t *oldset = sigmask_to_save();
 215         int ret;
 216
 217         /* Are we from a system call? */
 218         if (regs->faultnum == INT_SWINT_1) {
 219                 /* If so, check system call restarting.. */
 220                 switch (regs->regs[0]) {
 221                 case -ERESTART_RESTARTBLOCK:
 222                 case -ERESTARTNOHAND:
 223                         regs->regs[0] = -EINTR;
 224                         break;
 225
 226                 case -ERESTARTSYS:
 227                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 228                                 regs->regs[0] = -EINTR;
 229                                 break;
 230                         }
 231                         /* fallthrough */
 232                 case -ERESTARTNOINTR:
 233                         /* Reload caller-saves to restore r0..r5 and r10. */
 234                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 235                         regs->regs[0] = regs->orig_r0;
 236                         regs->pc -= 8;
 237                 }
 238         }
 239
 240         /* Set up the stack frame */
 241 #ifdef CONFIG_COMPAT
 242         if (is_compat_task())
 243                 ret = compat_setup_rt_frame(ksig, oldset, regs);
 244         else
 245 #endif
 246                 ret = setup_rt_frame(ksig, oldset, regs);
 247
 248         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 249 }
 250
 251 /*
 252  * Note that 'init' is a special process: it doesn't get signals it doesn't
 253  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 254  * mistake.
 255  */
 256 void do_signal(struct pt_regs *regs)
 257 {
 258         struct ksignal ksig;
 259
 260         /*
 261          * i386 will check if we're coming from kernel mode and bail out
 262          * here.  In my experience this just turns weird crashes into
 263          * weird spin-hangs.  But if we find a case where this seems
 264          * helpful, we can reinstate the check on "!user_mode(regs)".
 265          */
 266
 267         if (get_signal(&ksig)) {
 268                 /* Whee! Actually deliver the signal.  */
 269                 handle_signal(&ksig, regs);
 270                 goto done;
 271         }
 272
 273         /* Did we come from a system call? */
 274         if (regs->faultnum == INT_SWINT_1) {
 275                 /* Restart the system call - no handlers present */
 276                 switch (regs->regs[0]) {
 277                 case -ERESTARTNOHAND:
 278                 case -ERESTARTSYS:
 279                 case -ERESTARTNOINTR:
 280                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 281                         regs->regs[0] = regs->orig_r0;
 282                         regs->pc -= 8;
 283                         break;
 284
 285                 case -ERESTART_RESTARTBLOCK:
 286                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 287                         regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
 288                         regs->pc -= 8;
 289                         break;
 290                 }
 291         }
 292
 293         /* If there's no signal to deliver, just put the saved sigmask back. */
 294         restore_saved_sigmask();
 295
 296 done:
 297         /* Avoid double syscall restart if there are nested signals. */
 298         regs->faultnum = INT_SWINT_1_SIGRETURN;
 299 }
 300
 301 int show_unhandled_signals = 1;
 302
 303 static int __init crashinfo(char *str)
 304 {
 305         const char *word;
 306
 307         if (*str == '\0')
 308                 show_unhandled_signals = 2;
 309         else if (*str != '=' || kstrtoint(++str, 0, &show_unhandled_signals) != 0)
 310                 return 0;
 311
 312         switch (show_unhandled_signals) {
 313         case 0:
 314                 word = "No";
 315                 break;
 316         case 1:
 317                 word = "One-line";
 318                 break;
 319         default:
 320                 word = "Detailed";
 321                 break;
 322         }
 323         pr_info("%s crash reports will be generated on the console\n", word);
 324         return 1;
 325 }
 326 __setup("crashinfo", crashinfo);
 327
 328 static void dump_mem(void __user *address)
 329 {
 330         void __user *addr;
 331         enum { region_size = 256, bytes_per_line = 16 };
 332         int i, j, k;
 333         int found_readable_mem = 0;
 334
 335         if (!access_ok(VERIFY_READ, address, 1)) {
 336                 pr_err("Not dumping at address 0x%lx (kernel address)\n",
 337                        (unsigned long)address);
 338                 return;
 339         }
 340
 341         addr = (void __user *)
 342                 (((unsigned long)address & -bytes_per_line) - region_size/2);
 343         if (addr > address)
 344                 addr = NULL;
 345         for (i = 0; i < region_size;
 346              addr += bytes_per_line, i += bytes_per_line) {
 347                 unsigned char buf[bytes_per_line];
 348                 char line[100];
 349                 if (copy_from_user(buf, addr, bytes_per_line))
 350                         continue;
 351                 if (!found_readable_mem) {
 352                         pr_err("Dumping memory around address 0x%lx:\n",
 353                                (unsigned long)address);
 354                         found_readable_mem = 1;
 355                 }
 356                 j = sprintf(line, REGFMT ":", (unsigned long)addr);
 357                 for (k = 0; k < bytes_per_line; ++k)
 358                         j += sprintf(&line[j], " %02x", buf[k]);
 359                 pr_err("%s\n", line);
 360         }
 361         if (!found_readable_mem)
 362                 pr_err("No readable memory around address 0x%lx\n",
 363                        (unsigned long)address);
 364 }
 365
 366 void trace_unhandled_signal(const char *type, struct pt_regs *regs,
 367                             unsigned long address, int sig)
 368 {
 369         struct task_struct *tsk = current;
 370
 371         if (show_unhandled_signals == 0)
 372                 return;
 373
 374         /* If the signal is handled, don't show it here. */
 375         if (!is_global_init(tsk)) {
 376                 void __user *handler =
 377                         tsk->sighand->action[sig-1].sa.sa_handler;
 378                 if (handler != SIG_IGN && handler != SIG_DFL)
 379                         return;
 380         }
 381
 382         /* Rate-limit the one-line output, not the detailed output. */
 383         if (show_unhandled_signals <= 1 && !printk_ratelimit())
 384                 return;
 385
 386         printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d",
 387                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 388                tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig);
 389
 390         print_vma_addr(KERN_CONT " in ", regs->pc);
 391
 392         printk(KERN_CONT "\n");
 393
 394         if (show_unhandled_signals > 1) {
 395                 switch (sig) {
 396                 case SIGILL:
 397                 case SIGFPE:
 398                 case SIGSEGV:
 399                 case SIGBUS:
 400                         pr_err("User crash: signal %d, trap %ld, address 0x%lx\n",
 401                                sig, regs->faultnum, address);
 402                         show_regs(regs);
 403                         dump_mem((void __user *)address);
 404                         break;
 405                 default:
 406                         pr_err("User crash: signal %d, trap %ld\n",
 407                                sig, regs->faultnum);
 408                         break;
 409                 }
 410         }
 411 }