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 k_sigaction *ka, struct pt_regs *regs,
  40                           size_t frame_size)
  41 {
  42         unsigned long sp = regs->r29;
  43
  44         /* check if we would overflow the alt stack */
  45         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
  46                 return (void __user __force *)-1UL;
  47
  48         /* Switch to signal stack if appropriate */
  49         if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
  50                 sp = current->sas_ss_sp + current->sas_ss_size;
  51
  52         return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1));
  53 }
  54
  55 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
  56 {
  57         unsigned long tmp;
  58         int err = 0;
  59
  60         err |= copy_to_user(&sc->sc_regs.r0, &regs->r00,
  61                             32*sizeof(unsigned long));
  62
  63         err |= __put_user(regs->sa0, &sc->sc_regs.sa0);
  64         err |= __put_user(regs->lc0, &sc->sc_regs.lc0);
  65         err |= __put_user(regs->sa1, &sc->sc_regs.sa1);
  66         err |= __put_user(regs->lc1, &sc->sc_regs.lc1);
  67         err |= __put_user(regs->m0, &sc->sc_regs.m0);
  68         err |= __put_user(regs->m1, &sc->sc_regs.m1);
  69         err |= __put_user(regs->usr, &sc->sc_regs.usr);
  70         err |= __put_user(regs->preds, &sc->sc_regs.p3_0);
  71         err |= __put_user(regs->gp, &sc->sc_regs.gp);
  72         err |= __put_user(regs->ugp, &sc->sc_regs.ugp);
  73 #if CONFIG_HEXAGON_ARCH_VERSION >= 4
  74         err |= __put_user(regs->cs0, &sc->sc_regs.cs0);
  75         err |= __put_user(regs->cs1, &sc->sc_regs.cs1);
  76 #endif
  77         tmp = pt_elr(regs); err |= __put_user(tmp, &sc->sc_regs.pc);
  78         tmp = pt_cause(regs); err |= __put_user(tmp, &sc->sc_regs.cause);
  79         tmp = pt_badva(regs); err |= __put_user(tmp, &sc->sc_regs.badva);
  80
  81         return err;
  82 }
  83
  84 static int restore_sigcontext(struct pt_regs *regs,
  85                               struct sigcontext __user *sc)
  86 {
  87         unsigned long tmp;
  88         int err = 0;
  89
  90         err |= copy_from_user(&regs->r00, &sc->sc_regs.r0,
  91                               32 * sizeof(unsigned long));
  92
  93         err |= __get_user(regs->sa0, &sc->sc_regs.sa0);
  94         err |= __get_user(regs->lc0, &sc->sc_regs.lc0);
  95         err |= __get_user(regs->sa1, &sc->sc_regs.sa1);
  96         err |= __get_user(regs->lc1, &sc->sc_regs.lc1);
  97         err |= __get_user(regs->m0, &sc->sc_regs.m0);
  98         err |= __get_user(regs->m1, &sc->sc_regs.m1);
  99         err |= __get_user(regs->usr, &sc->sc_regs.usr);
 100         err |= __get_user(regs->preds, &sc->sc_regs.p3_0);
 101         err |= __get_user(regs->gp, &sc->sc_regs.gp);
 102         err |= __get_user(regs->ugp, &sc->sc_regs.ugp);
 103 #if CONFIG_HEXAGON_ARCH_VERSION >= 4
 104         err |= __get_user(regs->cs0, &sc->sc_regs.cs0);
 105         err |= __get_user(regs->cs1, &sc->sc_regs.cs1);
 106 #endif
 107         err |= __get_user(tmp, &sc->sc_regs.pc); pt_set_elr(regs, tmp);
 108
 109         return err;
 110 }
 111
 112 /*
 113  * Setup signal stack frame with siginfo structure
 114  */
 115 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
 116                           sigset_t *set,  struct pt_regs *regs)
 117 {
 118         int err = 0;
 119         struct rt_sigframe __user *frame;
 120         struct hexagon_vdso *vdso = current->mm->context.vdso;
 121
 122         frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe));
 123
 124         if (!access_ok(VERIFY_WRITE, frame, sizeof(struct rt_sigframe)))
 125                 goto    sigsegv;
 126
 127         if (copy_siginfo_to_user(&frame->info, info))
 128                 goto    sigsegv;
 129
 130         /* The on-stack signal trampoline is no longer executed;
 131          * however, the libgcc signal frame unwinding code checks for
 132          * the presence of these two numeric magic values.
 133          */
 134         err |= __put_user(0x7800d166, &frame->tramp[0]);
 135         err |= __put_user(0x5400c004, &frame->tramp[1]);
 136         err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
 137         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 138         err |= __save_altstack(&frame->uc.uc_stack, user_stack_pointer(regs));
 139         if (err)
 140                 goto sigsegv;
 141
 142         /* Load r0/r1 pair with signumber/siginfo pointer... */
 143         regs->r0100 = ((unsigned long long)((unsigned long)&frame->info) << 32)
 144                 | (unsigned long long)signr;
 145         regs->r02 = (unsigned long) &frame->uc;
 146         regs->r31 = (unsigned long) vdso->rt_signal_trampoline;
 147         pt_psp(regs) = (unsigned long) frame;
 148         pt_set_elr(regs, (unsigned long)ka->sa.sa_handler);
 149
 150         return 0;
 151
 152 sigsegv:
 153         force_sigsegv(signr, current);
 154         return -EFAULT;
 155 }
 156
 157 /*
 158  * Setup invocation of signal handler
 159  */
 160 static void handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka,
 161                          struct pt_regs *regs)
 162 {
 163         /*
 164          * If we're handling a signal that aborted a system call,
 165          * set up the error return value before adding the signal
 166          * frame to the stack.
 167          */
 168
 169         if (regs->syscall_nr >= 0) {
 170                 switch (regs->r00) {
 171                 case -ERESTART_RESTARTBLOCK:
 172                 case -ERESTARTNOHAND:
 173                         regs->r00 = -EINTR;
 174                         break;
 175                 case -ERESTARTSYS:
 176                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 177                                 regs->r00 = -EINTR;
 178                                 break;
 179                         }
 180                         /* Fall through */
 181                 case -ERESTARTNOINTR:
 182                         regs->r06 = regs->syscall_nr;
 183                         pt_set_elr(regs, pt_elr(regs) - 4);
 184                         regs->r00 = regs->restart_r0;
 185                         break;
 186                 default:
 187                         break;
 188                 }
 189         }
 190
 191         /*
 192          * Set up the stack frame; not doing the SA_SIGINFO thing.  We
 193          * only set up the rt_frame flavor.
 194          */
 195         /* If there was an error on setup, no signal was delivered. */
 196         if (setup_rt_frame(sig, ka, info, sigmask_to_save(), regs) < 0)
 197                 return;
 198
 199         signal_delivered(sig, info, ka, regs,
 200                         test_thread_flag(TIF_SINGLESTEP));
 201 }
 202
 203 /*
 204  * Called from return-from-event code.
 205  */
 206 void do_signal(struct pt_regs *regs)
 207 {
 208         struct k_sigaction sigact;
 209         siginfo_t info;
 210         int signo;
 211
 212         if (!user_mode(regs))
 213                 return;
 214
 215         signo = get_signal_to_deliver(&info, &sigact, regs, NULL);
 216
 217         if (signo > 0) {
 218                 handle_signal(signo, &info, &sigact, regs);
 219                 return;
 220         }
 221
 222         /*
 223          * No (more) signals; if we came from a system call, handle the restart.
 224          */
 225
 226         if (regs->syscall_nr >= 0) {
 227                 switch (regs->r00) {
 228                 case -ERESTARTNOHAND:
 229                 case -ERESTARTSYS:
 230                 case -ERESTARTNOINTR:
 231                         regs->r06 = regs->syscall_nr;
 232                         break;
 233                 case -ERESTART_RESTARTBLOCK:
 234                         regs->r06 = __NR_restart_syscall;
 235                         break;
 236                 default:
 237                         goto no_restart;
 238                 }
 239                 pt_set_elr(regs, pt_elr(regs) - 4);
 240                 regs->r00 = regs->restart_r0;
 241         }
 242
 243 no_restart:
 244         /* If there's no signal to deliver, put the saved sigmask back */
 245         restore_saved_sigmask();
 246 }
 247
 248 /*
 249  * Architecture-specific wrappers for signal-related system calls
 250  */
 251
 252 asmlinkage int sys_rt_sigreturn(void)
 253 {
 254         struct pt_regs *regs = current_pt_regs();
 255         struct rt_sigframe __user *frame;
 256         sigset_t blocked;
 257
 258         /* Always make any pending restarted system calls return -EINTR */
 259         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 260
 261         frame = (struct rt_sigframe __user *)pt_psp(regs);
 262         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 263                 goto badframe;
 264         if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked)))
 265                 goto badframe;
 266
 267         set_current_blocked(&blocked);
 268
 269         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 270                 goto badframe;
 271
 272         /* Restore the user's stack as well */
 273         pt_psp(regs) = regs->r29;
 274
 275         regs->syscall_nr = -1;
 276
 277         if (restore_altstack(&frame->uc.uc_stack))
 278                 goto badframe;
 279
 280         return regs->r00;
 281
 282 badframe:
 283         force_sig(SIGSEGV, current);
 284         return 0;
 285 }