arch/hexagon/kernel/signal.c

   1 /*
   2  * Signal support for Hexagon processor
   3  *
   4  * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 and
   8  * only version 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA.
  19  */
  20
  21 #include <linux/linkage.h>
  22 #include <linux/syscalls.h>
  23 #include <linux/freezer.h>
  24 #include <linux/tracehook.h>
  25 #include <asm/registers.h>
  26 #include <asm/thread_info.h>
  27 #include <asm/unistd.h>
  28 #include <asm/uaccess.h>
  29 #include <asm/ucontext.h>
  30 #include <asm/cacheflush.h>
  31 #include <asm/signal.h>
  32 #include <asm/vdso.h>
  33
  34 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  35
  36 struct rt_sigframe {
  37         unsigned long tramp[2];
  38         struct siginfo info;
  39         struct ucontext uc;
  40 };
  41
  42 static void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
  43                           size_t frame_size)
  44 {
  45         unsigned long sp = regs->r29;
  46
  47         /* Switch to signal stack if appropriate */
  48         if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
  49                 sp = current->sas_ss_sp + current->sas_ss_size;
  50
  51         return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1));
  52 }
  53
  54 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
  55 {
  56         unsigned long tmp;
  57         int err = 0;
  58
  59         err |= copy_to_user(&sc->sc_regs.r0, &regs->r00,
  60                             32*sizeof(unsigned long));
  61
  62         err |= __put_user(regs->sa0, &sc->sc_regs.sa0);
  63         err |= __put_user(regs->lc0, &sc->sc_regs.lc0);
  64         err |= __put_user(regs->sa1, &sc->sc_regs.sa1);
  65         err |= __put_user(regs->lc1, &sc->sc_regs.lc1);
  66         err |= __put_user(regs->m0, &sc->sc_regs.m0);
  67         err |= __put_user(regs->m1, &sc->sc_regs.m1);
  68         err |= __put_user(regs->usr, &sc->sc_regs.usr);
  69         err |= __put_user(regs->preds, &sc->sc_regs.p3_0);
  70         err |= __put_user(regs->gp, &sc->sc_regs.gp);
  71         err |= __put_user(regs->ugp, &sc->sc_regs.ugp);
  72
  73         tmp = pt_elr(regs); err |= __put_user(tmp, &sc->sc_regs.pc);
  74         tmp = pt_cause(regs); err |= __put_user(tmp, &sc->sc_regs.cause);
  75         tmp = pt_badva(regs); err |= __put_user(tmp, &sc->sc_regs.badva);
  76
  77         return err;
  78 }
  79
  80 static int restore_sigcontext(struct pt_regs *regs,
  81                               struct sigcontext __user *sc)
  82 {
  83         unsigned long tmp;
  84         int err = 0;
  85
  86         err |= copy_from_user(&regs->r00, &sc->sc_regs.r0,
  87                               32 * sizeof(unsigned long));
  88
  89         err |= __get_user(regs->sa0, &sc->sc_regs.sa0);
  90         err |= __get_user(regs->lc0, &sc->sc_regs.lc0);
  91         err |= __get_user(regs->sa1, &sc->sc_regs.sa1);
  92         err |= __get_user(regs->lc1, &sc->sc_regs.lc1);
  93         err |= __get_user(regs->m0, &sc->sc_regs.m0);
  94         err |= __get_user(regs->m1, &sc->sc_regs.m1);
  95         err |= __get_user(regs->usr, &sc->sc_regs.usr);
  96         err |= __get_user(regs->preds, &sc->sc_regs.p3_0);
  97         err |= __get_user(regs->gp, &sc->sc_regs.gp);
  98         err |= __get_user(regs->ugp, &sc->sc_regs.ugp);
  99
 100         err |= __get_user(tmp, &sc->sc_regs.pc); pt_set_elr(regs, tmp);
 101
 102         return err;
 103 }
 104
 105 /*
 106  * Setup signal stack frame with siginfo structure
 107  */
 108 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
 109                           sigset_t *set,  struct pt_regs *regs)
 110 {
 111         int err = 0;
 112         struct rt_sigframe __user *frame;
 113         struct hexagon_vdso *vdso = current->mm->context.vdso;
 114
 115         frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe));
 116
 117         if (!access_ok(VERIFY_WRITE, frame, sizeof(struct rt_sigframe)))
 118                 goto    sigsegv;
 119
 120         if (copy_siginfo_to_user(&frame->info, info))
 121                 goto    sigsegv;
 122
 123         /* The on-stack signal trampoline is no longer executed;
 124          * however, the libgcc signal frame unwinding code checks for
 125          * the presence of these two numeric magic values.
 126          */
 127         err |= __put_user(0x7800d166, &frame->tramp[0]);
 128         err |= __put_user(0x5400c004, &frame->tramp[1]);
 129         err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
 130         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 131         if (err)
 132                 goto sigsegv;
 133
 134         /* Load r0/r1 pair with signumber/siginfo pointer... */
 135         regs->r0100 = ((unsigned long long)((unsigned long)&frame->info) << 32)
 136                 | (unsigned long long)signr;
 137         regs->r02 = (unsigned long) &frame->uc;
 138         regs->r31 = (unsigned long) vdso->rt_signal_trampoline;
 139         pt_psp(regs) = (unsigned long) frame;
 140         pt_set_elr(regs, (unsigned long)ka->sa.sa_handler);
 141
 142         return 0;
 143
 144 sigsegv:
 145         force_sigsegv(signr, current);
 146         return -EFAULT;
 147 }
 148
 149 /*
 150  * Setup invocation of signal handler
 151  */
 152 static int handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka,
 153                          sigset_t *oldset, struct pt_regs *regs)
 154 {
 155         int rc;
 156
 157         /*
 158          * If we're handling a signal that aborted a system call,
 159          * set up the error return value before adding the signal
 160          * frame to the stack.
 161          */
 162
 163         if (regs->syscall_nr >= 0) {
 164                 switch (regs->r00) {
 165                 case -ERESTART_RESTARTBLOCK:
 166                 case -ERESTARTNOHAND:
 167                         regs->r00 = -EINTR;
 168                         break;
 169                 case -ERESTARTSYS:
 170                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 171                                 regs->r00 = -EINTR;
 172                                 break;
 173                         }
 174                         /* Fall through */
 175                 case -ERESTARTNOINTR:
 176                         regs->r06 = regs->syscall_nr;
 177                         pt_set_elr(regs, pt_elr(regs) - 4);
 178                         regs->r00 = regs->restart_r0;
 179                         break;
 180                 default:
 181                         break;
 182                 }
 183         }
 184
 185         /*
 186          * Set up the stack frame; not doing the SA_SIGINFO thing.  We
 187          * only set up the rt_frame flavor.
 188          */
 189         rc = setup_rt_frame(sig, ka, info, oldset, regs);
 190
 191         /* If there was an error on setup, no signal was delivered. */
 192         if (rc)
 193                 return rc;
 194
 195         block_sigmask(ka, sig);
 196
 197         return 0;
 198 }
 199
 200 /*
 201  * Called from return-from-event code.
 202  */
 203 static void do_signal(struct pt_regs *regs)
 204 {
 205         struct k_sigaction sigact;
 206         siginfo_t info;
 207         int signo;
 208
 209         if (!user_mode(regs))
 210                 return;
 211
 212         if (try_to_freeze())
 213                 goto no_signal;
 214
 215         signo = get_signal_to_deliver(&info, &sigact, regs, NULL);
 216
 217         if (signo > 0) {
 218                 sigset_t *oldset;
 219
 220                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
 221                         oldset = &current->saved_sigmask;
 222                 else
 223                         oldset = &current->blocked;
 224
 225                 if (handle_signal(signo, &info, &sigact, oldset, regs) == 0) {
 226                         /*
 227                          * Successful delivery case.  The saved sigmask is
 228                          * stored in the signal frame, and will be restored
 229                          * by sigreturn.  We can clear the TIF flag.
 230                          */
 231                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 232
 233                         tracehook_signal_handler(signo, &info, &sigact, regs,
 234                                 test_thread_flag(TIF_SINGLESTEP));
 235                 }
 236                 return;
 237         }
 238
 239 no_signal:
 240         /*
 241          * If we came from a system call, handle the restart.
 242          */
 243         if (regs->syscall_nr >= 0) {
 244                 switch (regs->r00) {
 245                 case -ERESTARTNOHAND:
 246                 case -ERESTARTSYS:
 247                 case -ERESTARTNOINTR:
 248                         regs->r06 = regs->syscall_nr;
 249                         break;
 250                 case -ERESTART_RESTARTBLOCK:
 251                         regs->r06 = __NR_restart_syscall;
 252                         break;
 253                 default:
 254                         goto no_restart;
 255                 }
 256                 pt_set_elr(regs, pt_elr(regs) - 4);
 257                 regs->r00 = regs->restart_r0;
 258         }
 259
 260 no_restart:
 261         /* If there's no signal to deliver, put the saved sigmask back */
 262         restore_saved_sigmask();
 263 }
 264
 265 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
 266 {
 267         if (thread_info_flags & _TIF_SIGPENDING)
 268                 do_signal(regs);
 269
 270         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 271                 clear_thread_flag(TIF_NOTIFY_RESUME);
 272                 tracehook_notify_resume(regs);
 273         }
 274 }
 275
 276 /*
 277  * Architecture-specific wrappers for signal-related system calls
 278  */
 279 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 280 {
 281         struct pt_regs *regs = current_thread_info()->regs;
 282
 283         return do_sigaltstack(uss, uoss, regs->r29);
 284 }
 285
 286 asmlinkage int sys_rt_sigreturn(void)
 287 {
 288         struct pt_regs *regs = current_thread_info()->regs;
 289         struct rt_sigframe __user *frame;
 290         sigset_t blocked;
 291
 292         /* Always make any pending restarted system calls return -EINTR */
 293         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 294
 295         frame = (struct rt_sigframe __user *)pt_psp(regs);
 296         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 297                 goto badframe;
 298         if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked)))
 299                 goto badframe;
 300
 301         sigdelsetmask(&blocked, ~_BLOCKABLE);
 302         set_current_blocked(&blocked);
 303
 304         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 305                 goto badframe;
 306
 307         /* Restore the user's stack as well */
 308         pt_psp(regs) = regs->r29;
 309
 310         /*
 311          * Leave a trace in the stack frame that this was a sigreturn.
 312          * If the system call is to replay, we've already restored the
 313          * number in the GPR slot and it will be regenerated on the
 314          * new system call trap entry. Note that if restore_sigcontext()
 315          * did something other than a bulk copy of the pt_regs struct,
 316          * we could avoid this assignment by simply not overwriting
 317          * regs->syscall_nr.
 318          */
 319         regs->syscall_nr = __NR_rt_sigreturn;
 320
 321         /*
 322          * If we were meticulous, we'd only call this if we knew that
 323          * we were actually going to use an alternate stack, and we'd
 324          * consider any error to be fatal.  What we do here, in common
 325          * with many other architectures, is call it blindly and only
 326          * consider the -EFAULT return case to be proof of a problem.
 327          */
 328         if (do_sigaltstack(&frame->uc.uc_stack, NULL, pt_psp(regs)) == -EFAULT)
 329                 goto badframe;
 330
 331         return 0;
 332
 333 badframe:
 334         force_sig(SIGSEGV, current);
 335         return 0;
 336 }