arch/hexagon/kernel/signal.c

   1 /*
   2  * Signal support for Hexagon processor
   3  *
   4  * Copyright (c) 2010-2012, 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 ksignal *ksig, struct pt_regs *regs,
  40                           size_t frame_size)
  41 {
  42         unsigned long sp = sigsp(regs->r29, ksig);
  43
  44         return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1));
  45 }
  46
  47 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
  48 {
  49         unsigned long tmp;
  50         int err = 0;
  51
  52         err |= copy_to_user(&sc->sc_regs.r0, &regs->r00,
  53                             32*sizeof(unsigned long));
  54
  55         err |= __put_user(regs->sa0, &sc->sc_regs.sa0);
  56         err |= __put_user(regs->lc0, &sc->sc_regs.lc0);
  57         err |= __put_user(regs->sa1, &sc->sc_regs.sa1);
  58         err |= __put_user(regs->lc1, &sc->sc_regs.lc1);
  59         err |= __put_user(regs->m0, &sc->sc_regs.m0);
  60         err |= __put_user(regs->m1, &sc->sc_regs.m1);
  61         err |= __put_user(regs->usr, &sc->sc_regs.usr);
  62         err |= __put_user(regs->preds, &sc->sc_regs.p3_0);
  63         err |= __put_user(regs->gp, &sc->sc_regs.gp);
  64         err |= __put_user(regs->ugp, &sc->sc_regs.ugp);
  65 #if CONFIG_HEXAGON_ARCH_VERSION >= 4
  66         err |= __put_user(regs->cs0, &sc->sc_regs.cs0);
  67         err |= __put_user(regs->cs1, &sc->sc_regs.cs1);
  68 #endif
  69         tmp = pt_elr(regs); err |= __put_user(tmp, &sc->sc_regs.pc);
  70         tmp = pt_cause(regs); err |= __put_user(tmp, &sc->sc_regs.cause);
  71         tmp = pt_badva(regs); err |= __put_user(tmp, &sc->sc_regs.badva);
  72
  73         return err;
  74 }
  75
  76 static int restore_sigcontext(struct pt_regs *regs,
  77                               struct sigcontext __user *sc)
  78 {
  79         unsigned long tmp;
  80         int err = 0;
  81
  82         err |= copy_from_user(&regs->r00, &sc->sc_regs.r0,
  83                               32 * sizeof(unsigned long));
  84
  85         err |= __get_user(regs->sa0, &sc->sc_regs.sa0);
  86         err |= __get_user(regs->lc0, &sc->sc_regs.lc0);
  87         err |= __get_user(regs->sa1, &sc->sc_regs.sa1);
  88         err |= __get_user(regs->lc1, &sc->sc_regs.lc1);
  89         err |= __get_user(regs->m0, &sc->sc_regs.m0);
  90         err |= __get_user(regs->m1, &sc->sc_regs.m1);
  91         err |= __get_user(regs->usr, &sc->sc_regs.usr);
  92         err |= __get_user(regs->preds, &sc->sc_regs.p3_0);
  93         err |= __get_user(regs->gp, &sc->sc_regs.gp);
  94         err |= __get_user(regs->ugp, &sc->sc_regs.ugp);
  95 #if CONFIG_HEXAGON_ARCH_VERSION >= 4
  96         err |= __get_user(regs->cs0, &sc->sc_regs.cs0);
  97         err |= __get_user(regs->cs1, &sc->sc_regs.cs1);
  98 #endif
  99         err |= __get_user(tmp, &sc->sc_regs.pc); pt_set_elr(regs, tmp);
 100
 101         return err;
 102 }
 103
 104 /*
 105  * Setup signal stack frame with siginfo structure
 106  */
 107 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 108                           struct pt_regs *regs)
 109 {
 110         int err = 0;
 111         struct rt_sigframe __user *frame;
 112         struct hexagon_vdso *vdso = current->mm->context.vdso;
 113
 114         frame = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
 115
 116         if (!access_ok(VERIFY_WRITE, frame, sizeof(struct rt_sigframe)))
 117                 return -EFAULT;
 118
 119         if (copy_siginfo_to_user(&frame->info, &ksig->info))
 120                 return -EFAULT;
 121
 122         /* The on-stack signal trampoline is no longer executed;
 123          * however, the libgcc signal frame unwinding code checks for
 124          * the presence of these two numeric magic values.
 125          */
 126         err |= __put_user(0x7800d166, &frame->tramp[0]);
 127         err |= __put_user(0x5400c004, &frame->tramp[1]);
 128         err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
 129         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 130         err |= __save_altstack(&frame->uc.uc_stack, user_stack_pointer(regs));
 131         if (err)
 132                 return -EFAULT;
 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)ksig->sig;
 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)ksig->ka.sa.sa_handler);
 141
 142         return 0;
 143 }
 144
 145 /*
 146  * Setup invocation of signal handler
 147  */
 148 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 149 {
 150         int ret;
 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 (!(ksig->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         ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
 186
 187         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 188 }
 189
 190 /*
 191  * Called from return-from-event code.
 192  */
 193 void do_signal(struct pt_regs *regs)
 194 {
 195         struct ksignal ksig;
 196
 197         if (!user_mode(regs))
 198                 return;
 199
 200         if (get_signal(&ksig)) {
 201                 handle_signal(&ksig, regs);
 202                 return;
 203         }
 204
 205         /*
 206          * No (more) signals; if we came from a system call, handle the restart.
 207          */
 208
 209         if (regs->syscall_nr >= 0) {
 210                 switch (regs->r00) {
 211                 case -ERESTARTNOHAND:
 212                 case -ERESTARTSYS:
 213                 case -ERESTARTNOINTR:
 214                         regs->r06 = regs->syscall_nr;
 215                         break;
 216                 case -ERESTART_RESTARTBLOCK:
 217                         regs->r06 = __NR_restart_syscall;
 218                         break;
 219                 default:
 220                         goto no_restart;
 221                 }
 222                 pt_set_elr(regs, pt_elr(regs) - 4);
 223                 regs->r00 = regs->restart_r0;
 224         }
 225
 226 no_restart:
 227         /* If there's no signal to deliver, put the saved sigmask back */
 228         restore_saved_sigmask();
 229 }
 230
 231 /*
 232  * Architecture-specific wrappers for signal-related system calls
 233  */
 234
 235 asmlinkage int sys_rt_sigreturn(void)
 236 {
 237         struct pt_regs *regs = current_pt_regs();
 238         struct rt_sigframe __user *frame;
 239         sigset_t blocked;
 240
 241         /* Always make any pending restarted system calls return -EINTR */
 242         current->restart_block.fn = do_no_restart_syscall;
 243
 244         frame = (struct rt_sigframe __user *)pt_psp(regs);
 245         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 246                 goto badframe;
 247         if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked)))
 248                 goto badframe;
 249
 250         set_current_blocked(&blocked);
 251
 252         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 253                 goto badframe;
 254
 255         /* Restore the user's stack as well */
 256         pt_psp(regs) = regs->r29;
 257
 258         regs->syscall_nr = -1;
 259
 260         if (restore_altstack(&frame->uc.uc_stack))
 261                 goto badframe;
 262
 263         return regs->r00;
 264
 265 badframe:
 266         force_sig(SIGSEGV, current);
 267         return 0;
 268 }