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
  43 SYSCALL_DEFINE3(sigaltstack, const stack_t __user *, uss,
  44                 stack_t __user *, uoss, struct pt_regs *, regs)
  45 {
  46         return do_sigaltstack(uss, uoss, regs->sp);
  47 }
  48
  49
  50 /*
  51  * Do a signal return; undo the signal stack.
  52  */
  53
  54 int restore_sigcontext(struct pt_regs *regs,
  55                        struct sigcontext __user *sc)
  56 {
  57         int err = 0;
  58         int i;
  59
  60         /* Always make any pending restarted system calls return -EINTR */
  61         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  62
  63         /*
  64          * Enforce that sigcontext is like pt_regs, and doesn't mess
  65          * up our stack alignment rules.
  66          */
  67         BUILD_BUG_ON(sizeof(struct sigcontext) != sizeof(struct pt_regs));
  68         BUILD_BUG_ON(sizeof(struct sigcontext) % 8 != 0);
  69
  70         for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
  71                 err |= __get_user(regs->regs[i], &sc->gregs[i]);
  72
  73         /* Ensure that the PL is always set to USER_PL. */
  74         regs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(regs->ex1));
  75
  76         regs->faultnum = INT_SWINT_1_SIGRETURN;
  77
  78         return err;
  79 }
  80
  81 /* The assembly shim for this function arranges to ignore the return value. */
  82 SYSCALL_DEFINE1(rt_sigreturn, struct pt_regs *, regs)
  83 {
  84         struct rt_sigframe __user *frame =
  85                 (struct rt_sigframe __user *)(regs->sp);
  86         sigset_t set;
  87
  88         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  89                 goto badframe;
  90         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  91                 goto badframe;
  92
  93         sigdelsetmask(&set, ~_BLOCKABLE);
  94         spin_lock_irq(&current->sighand->siglock);
  95         current->blocked = set;
  96         recalc_sigpending();
  97         spin_unlock_irq(&current->sighand->siglock);
  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         force_sig(SIGSEGV, current);
 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         force_sigsegv(sig, current);
 235         return -EFAULT;
 236 }
 237
 238 /*
 239  * OK, we're invoking a handler
 240  */
 241
 242 static int handle_signal(unsigned long sig, siginfo_t *info,
 243                          struct k_sigaction *ka, sigset_t *oldset,
 244                          struct pt_regs *regs)
 245 {
 246         int ret;
 247
 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 == 0) {
 280                 /* This code is only called from system calls or from
 281                  * the work_pending path in the return-to-user code, and
 282                  * either way we can re-enable interrupts unconditionally.
 283                  */
 284                 spin_lock_irq(&current->sighand->siglock);
 285                 sigorsets(&current->blocked,
 286                           &current->blocked, &ka->sa.sa_mask);
 287                 if (!(ka->sa.sa_flags & SA_NODEFER))
 288                         sigaddset(&current->blocked, sig);
 289                 recalc_sigpending();
 290                 spin_unlock_irq(&current->sighand->siglock);
 291         }
 292
 293         return ret;
 294 }
 295
 296 /*
 297  * Note that 'init' is a special process: it doesn't get signals it doesn't
 298  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 299  * mistake.
 300  */
 301 void do_signal(struct pt_regs *regs)
 302 {
 303         siginfo_t info;
 304         int signr;
 305         struct k_sigaction ka;
 306         sigset_t *oldset;
 307
 308         /*
 309          * i386 will check if we're coming from kernel mode and bail out
 310          * here.  In my experience this just turns weird crashes into
 311          * weird spin-hangs.  But if we find a case where this seems
 312          * helpful, we can reinstate the check on "!user_mode(regs)".
 313          */
 314
 315         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 316                 oldset = &current->saved_sigmask;
 317         else
 318                 oldset = &current->blocked;
 319
 320         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 321         if (signr > 0) {
 322                 /* Whee! Actually deliver the signal.  */
 323                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 324                         /*
 325                          * A signal was successfully delivered; the saved
 326                          * sigmask will have been stored in the signal frame,
 327                          * and will be restored by sigreturn, so we can simply
 328                          * clear the TS_RESTORE_SIGMASK flag.
 329                          */
 330                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 331                 }
 332
 333                 goto done;
 334         }
 335
 336         /* Did we come from a system call? */
 337         if (regs->faultnum == INT_SWINT_1) {
 338                 /* Restart the system call - no handlers present */
 339                 switch (regs->regs[0]) {
 340                 case -ERESTARTNOHAND:
 341                 case -ERESTARTSYS:
 342                 case -ERESTARTNOINTR:
 343                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 344                         regs->regs[0] = regs->orig_r0;
 345                         regs->pc -= 8;
 346                         break;
 347
 348                 case -ERESTART_RESTARTBLOCK:
 349                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 350                         regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
 351                         regs->pc -= 8;
 352                         break;
 353                 }
 354         }
 355
 356         /* If there's no signal to deliver, just put the saved sigmask back. */
 357         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 358                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 359                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 360         }
 361
 362 done:
 363         /* Avoid double syscall restart if there are nested signals. */
 364         regs->faultnum = INT_SWINT_1_SIGRETURN;
 365 }