arch/hexagon/kernel/signal.c

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