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 <linux/sched/task_stack.h>
  25
  26 #include <asm/registers.h>
  27 #include <asm/thread_info.h>
  28 #include <asm/unistd.h>
  29 #include <linux/uaccess.h>
  30 #include <asm/ucontext.h>
  31 #include <asm/cacheflush.h>
  32 #include <asm/signal.h>
  33 #include <asm/vdso.h>
  34
  35 struct rt_sigframe {
  36         unsigned long tramp[2];
  37         struct siginfo info;
  38         struct ucontext uc;
  39 };
  40
  41 static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
  42                           size_t frame_size)
  43 {
  44         unsigned long sp = sigsp(regs->r29, ksig);
  45
  46         return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1));
  47 }
  48
  49 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
  50 {
  51         unsigned long tmp;
  52         int err = 0;
  53
  54         err |= copy_to_user(&sc->sc_regs.r0, &regs->r00,
  55                             32*sizeof(unsigned long));
  56
  57         err |= __put_user(regs->sa0, &sc->sc_regs.sa0);
  58         err |= __put_user(regs->lc0, &sc->sc_regs.lc0);
  59         err |= __put_user(regs->sa1, &sc->sc_regs.sa1);
  60         err |= __put_user(regs->lc1, &sc->sc_regs.lc1);
  61         err |= __put_user(regs->m0, &sc->sc_regs.m0);
  62         err |= __put_user(regs->m1, &sc->sc_regs.m1);
  63         err |= __put_user(regs->usr, &sc->sc_regs.usr);
  64         err |= __put_user(regs->preds, &sc->sc_regs.p3_0);
  65         err |= __put_user(regs->gp, &sc->sc_regs.gp);
  66         err |= __put_user(regs->ugp, &sc->sc_regs.ugp);
  67 #if CONFIG_HEXAGON_ARCH_VERSION >= 4
  68         err |= __put_user(regs->cs0, &sc->sc_regs.cs0);
  69         err |= __put_user(regs->cs1, &sc->sc_regs.cs1);
  70 #endif
  71         tmp = pt_elr(regs); err |= __put_user(tmp, &sc->sc_regs.pc);
  72         tmp = pt_cause(regs); err |= __put_user(tmp, &sc->sc_regs.cause);
  73         tmp = pt_badva(regs); err |= __put_user(tmp, &sc->sc_regs.badva);
  74
  75         return err;
  76 }
  77
  78 static int restore_sigcontext(struct pt_regs *regs,
  79                               struct sigcontext __user *sc)
  80 {
  81         unsigned long tmp;
  82         int err = 0;
  83
  84         err |= copy_from_user(&regs->r00, &sc->sc_regs.r0,
  85                               32 * sizeof(unsigned long));
  86
  87         err |= __get_user(regs->sa0, &sc->sc_regs.sa0);
  88         err |= __get_user(regs->lc0, &sc->sc_regs.lc0);
  89         err |= __get_user(regs->sa1, &sc->sc_regs.sa1);
  90         err |= __get_user(regs->lc1, &sc->sc_regs.lc1);
  91         err |= __get_user(regs->m0, &sc->sc_regs.m0);
  92         err |= __get_user(regs->m1, &sc->sc_regs.m1);
  93         err |= __get_user(regs->usr, &sc->sc_regs.usr);
  94         err |= __get_user(regs->preds, &sc->sc_regs.p3_0);
  95         err |= __get_user(regs->gp, &sc->sc_regs.gp);
  96         err |= __get_user(regs->ugp, &sc->sc_regs.ugp);
  97 #if CONFIG_HEXAGON_ARCH_VERSION >= 4
  98         err |= __get_user(regs->cs0, &sc->sc_regs.cs0);
  99         err |= __get_user(regs->cs1, &sc->sc_regs.cs1);
 100 #endif
 101         err |= __get_user(tmp, &sc->sc_regs.pc); pt_set_elr(regs, tmp);
 102
 103         return err;
 104 }
 105
 106 /*
 107  * Setup signal stack frame with siginfo structure
 108  */
 109 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 110                           struct pt_regs *regs)
 111 {
 112         int err = 0;
 113         struct rt_sigframe __user *frame;
 114         struct hexagon_vdso *vdso = current->mm->context.vdso;
 115
 116         frame = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
 117
 118         if (!access_ok(VERIFY_WRITE, frame, sizeof(struct rt_sigframe)))
 119                 return -EFAULT;
 120
 121         if (copy_siginfo_to_user(&frame->info, &ksig->info))
 122                 return -EFAULT;
 123
 124         /* The on-stack signal trampoline is no longer executed;
 125          * however, the libgcc signal frame unwinding code checks for
 126          * the presence of these two numeric magic values.
 127          */
 128         err |= __put_user(0x7800d166, &frame->tramp[0]);
 129         err |= __put_user(0x5400c004, &frame->tramp[1]);
 130         err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
 131         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 132         err |= __save_altstack(&frame->uc.uc_stack, user_stack_pointer(regs));
 133         if (err)
 134                 return -EFAULT;
 135
 136         /* Load r0/r1 pair with signumber/siginfo pointer... */
 137         regs->r0100 = ((unsigned long long)((unsigned long)&frame->info) << 32)
 138                 | (unsigned long long)ksig->sig;
 139         regs->r02 = (unsigned long) &frame->uc;
 140         regs->r31 = (unsigned long) vdso->rt_signal_trampoline;
 141         pt_psp(regs) = (unsigned long) frame;
 142         pt_set_elr(regs, (unsigned long)ksig->ka.sa.sa_handler);
 143
 144         return 0;
 145 }
 146
 147 /*
 148  * Setup invocation of signal handler
 149  */
 150 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 151 {
 152         int ret;
 153
 154         /*
 155          * If we're handling a signal that aborted a system call,
 156          * set up the error return value before adding the signal
 157          * frame to the stack.
 158          */
 159
 160         if (regs->syscall_nr >= 0) {
 161                 switch (regs->r00) {
 162                 case -ERESTART_RESTARTBLOCK:
 163                 case -ERESTARTNOHAND:
 164                         regs->r00 = -EINTR;
 165                         break;
 166                 case -ERESTARTSYS:
 167                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 168                                 regs->r00 = -EINTR;
 169                                 break;
 170                         }
 171                         /* Fall through */
 172                 case -ERESTARTNOINTR:
 173                         regs->r06 = regs->syscall_nr;
 174                         pt_set_elr(regs, pt_elr(regs) - 4);
 175                         regs->r00 = regs->restart_r0;
 176                         break;
 177                 default:
 178                         break;
 179                 }
 180         }
 181
 182         /*
 183          * Set up the stack frame; not doing the SA_SIGINFO thing.  We
 184          * only set up the rt_frame flavor.
 185          */
 186         /* If there was an error on setup, no signal was delivered. */
 187         ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
 188
 189         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 190 }
 191
 192 /*
 193  * Called from return-from-event code.
 194  */
 195 void do_signal(struct pt_regs *regs)
 196 {
 197         struct ksignal ksig;
 198
 199         if (!user_mode(regs))
 200                 return;
 201
 202         if (get_signal(&ksig)) {
 203                 handle_signal(&ksig, regs);
 204                 return;
 205         }
 206
 207         /*
 208          * No (more) signals; if we came from a system call, handle the restart.
 209          */
 210
 211         if (regs->syscall_nr >= 0) {
 212                 switch (regs->r00) {
 213                 case -ERESTARTNOHAND:
 214                 case -ERESTARTSYS:
 215                 case -ERESTARTNOINTR:
 216                         regs->r06 = regs->syscall_nr;
 217                         break;
 218                 case -ERESTART_RESTARTBLOCK:
 219                         regs->r06 = __NR_restart_syscall;
 220                         break;
 221                 default:
 222                         goto no_restart;
 223                 }
 224                 pt_set_elr(regs, pt_elr(regs) - 4);
 225                 regs->r00 = regs->restart_r0;
 226         }
 227
 228 no_restart:
 229         /* If there's no signal to deliver, put the saved sigmask back */
 230         restore_saved_sigmask();
 231 }
 232
 233 /*
 234  * Architecture-specific wrappers for signal-related system calls
 235  */
 236
 237 asmlinkage int sys_rt_sigreturn(void)
 238 {
 239         struct pt_regs *regs = current_pt_regs();
 240         struct rt_sigframe __user *frame;
 241         sigset_t blocked;
 242
 243         /* Always make any pending restarted system calls return -EINTR */
 244         current->restart_block.fn = do_no_restart_syscall;
 245
 246         frame = (struct rt_sigframe __user *)pt_psp(regs);
 247         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 248                 goto badframe;
 249         if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked)))
 250                 goto badframe;
 251
 252         set_current_blocked(&blocked);
 253
 254         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 255                 goto badframe;
 256
 257         /* Restore the user's stack as well */
 258         pt_psp(regs) = regs->r29;
 259
 260         regs->syscall_nr = -1;
 261
 262         if (restore_altstack(&frame->uc.uc_stack))
 263                 goto badframe;
 264
 265         return regs->r00;
 266
 267 badframe:
 268         force_sig(SIGSEGV, current);
 269         return 0;
 270 }