arch/c6x/kernel/signal.c

   1 /*
   2  *  Port on Texas Instruments TMS320C6x architecture
   3  *
   4  *  Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
   5  *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
   6  *
   7  *  Updated for 2.6.34: Mark Salter <msalter@redhat.com>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License version 2 as
  11  *  published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/syscalls.h>
  17 #include <linux/tracehook.h>
  18
  19 #include <asm/ucontext.h>
  20 #include <asm/cacheflush.h>
  21
  22
  23 /*
  24  * Do a signal return, undo the signal stack.
  25  */
  26
  27 #define RETCODE_SIZE (9 << 2)   /* 9 instructions = 36 bytes */
  28
  29 struct rt_sigframe {
  30         struct siginfo __user *pinfo;
  31         void __user *puc;
  32         struct siginfo info;
  33         struct ucontext uc;
  34         unsigned long retcode[RETCODE_SIZE >> 2];
  35 };
  36
  37 static int restore_sigcontext(struct pt_regs *regs,
  38                               struct sigcontext __user *sc)
  39 {
  40         int err = 0;
  41
  42         /* The access_ok check was done by caller, so use __get_user here */
  43 #define COPY(x)  (err |= __get_user(regs->x, &sc->sc_##x))
  44
  45         COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
  46         COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
  47         COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
  48
  49         COPY(a16); COPY(a17); COPY(a18); COPY(a19);
  50         COPY(a20); COPY(a21); COPY(a22); COPY(a23);
  51         COPY(a24); COPY(a25); COPY(a26); COPY(a27);
  52         COPY(a28); COPY(a29); COPY(a30); COPY(a31);
  53         COPY(b16); COPY(b17); COPY(b18); COPY(b19);
  54         COPY(b20); COPY(b21); COPY(b22); COPY(b23);
  55         COPY(b24); COPY(b25); COPY(b26); COPY(b27);
  56         COPY(b28); COPY(b29); COPY(b30); COPY(b31);
  57
  58         COPY(csr); COPY(pc);
  59
  60 #undef COPY
  61
  62         return err;
  63 }
  64
  65 asmlinkage int do_rt_sigreturn(struct pt_regs *regs)
  66 {
  67         struct rt_sigframe __user *frame;
  68         sigset_t set;
  69
  70         /* Always make any pending restarted system calls return -EINTR */
  71         current->restart_block.fn = do_no_restart_syscall;
  72
  73         /*
  74          * Since we stacked the signal on a dword boundary,
  75          * 'sp' should be dword aligned here.  If it's
  76          * not, then the user is trying to mess with us.
  77          */
  78         if (regs->sp & 7)
  79                 goto badframe;
  80
  81         frame = (struct rt_sigframe __user *) ((unsigned long) regs->sp + 8);
  82
  83         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  84                 goto badframe;
  85         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  86                 goto badframe;
  87
  88         set_current_blocked(&set);
  89
  90         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  91                 goto badframe;
  92
  93         return regs->a4;
  94
  95 badframe:
  96         force_sig(SIGSEGV, current);
  97         return 0;
  98 }
  99
 100 static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 101                             unsigned long mask)
 102 {
 103         int err = 0;
 104
 105         err |= __put_user(mask, &sc->sc_mask);
 106
 107         /* The access_ok check was done by caller, so use __put_user here */
 108 #define COPY(x) (err |= __put_user(regs->x, &sc->sc_##x))
 109
 110         COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
 111         COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
 112         COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
 113
 114         COPY(a16); COPY(a17); COPY(a18); COPY(a19);
 115         COPY(a20); COPY(a21); COPY(a22); COPY(a23);
 116         COPY(a24); COPY(a25); COPY(a26); COPY(a27);
 117         COPY(a28); COPY(a29); COPY(a30); COPY(a31);
 118         COPY(b16); COPY(b17); COPY(b18); COPY(b19);
 119         COPY(b20); COPY(b21); COPY(b22); COPY(b23);
 120         COPY(b24); COPY(b25); COPY(b26); COPY(b27);
 121         COPY(b28); COPY(b29); COPY(b30); COPY(b31);
 122
 123         COPY(csr); COPY(pc);
 124
 125 #undef COPY
 126
 127         return err;
 128 }
 129
 130 static inline void __user *get_sigframe(struct ksignal *ksig,
 131                                         struct pt_regs *regs,
 132                                         unsigned long framesize)
 133 {
 134         unsigned long sp = sigsp(regs->sp, ksig);
 135
 136         /*
 137          * No matter what happens, 'sp' must be dword
 138          * aligned. Otherwise, nasty things will happen
 139          */
 140         return (void __user *)((sp - framesize) & ~7);
 141 }
 142
 143 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 144                           struct pt_regs *regs)
 145 {
 146         struct rt_sigframe __user *frame;
 147         unsigned long __user *retcode;
 148         int err = 0;
 149
 150         frame = get_sigframe(ksig, regs, sizeof(*frame));
 151
 152         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 153                 return -EFAULT;
 154
 155         err |= __put_user(&frame->info, &frame->pinfo);
 156         err |= __put_user(&frame->uc, &frame->puc);
 157         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 158
 159         /* Clear all the bits of the ucontext we don't use.  */
 160         err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
 161
 162         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
 163         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 164
 165         /* Set up to return from userspace */
 166         retcode = (unsigned long __user *) &frame->retcode;
 167
 168         /* The access_ok check was done above, so use __put_user here */
 169 #define COPY(x) (err |= __put_user(x, retcode++))
 170
 171         COPY(0x0000002AUL | (__NR_rt_sigreturn << 7));
 172                                 /* MVK __NR_rt_sigreturn,B0 */
 173         COPY(0x10000000UL);     /* SWE */
 174         COPY(0x00006000UL);     /* NOP 4 */
 175         COPY(0x00006000UL);     /* NOP 4 */
 176         COPY(0x00006000UL);     /* NOP 4 */
 177         COPY(0x00006000UL);     /* NOP 4 */
 178         COPY(0x00006000UL);     /* NOP 4 */
 179         COPY(0x00006000UL);     /* NOP 4 */
 180         COPY(0x00006000UL);     /* NOP 4 */
 181
 182 #undef COPY
 183
 184         if (err)
 185                 return -EFAULT;
 186
 187         flush_icache_range((unsigned long) &frame->retcode,
 188                            (unsigned long) &frame->retcode + RETCODE_SIZE);
 189
 190         retcode = (unsigned long __user *) &frame->retcode;
 191
 192         /* Change user context to branch to signal handler */
 193         regs->sp = (unsigned long) frame - 8;
 194         regs->b3 = (unsigned long) retcode;
 195         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 196
 197         /* Give the signal number to the handler */
 198         regs->a4 = ksig->sig;
 199
 200         /*
 201          * For realtime signals we must also set the second and third
 202          * arguments for the signal handler.
 203          *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 204          */
 205         regs->b4 = (unsigned long)&frame->info;
 206         regs->a6 = (unsigned long)&frame->uc;
 207
 208         return 0;
 209 }
 210
 211 static inline void
 212 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 213 {
 214         switch (regs->a4) {
 215         case -ERESTARTNOHAND:
 216                 if (!has_handler)
 217                         goto do_restart;
 218                 regs->a4 = -EINTR;
 219                 break;
 220
 221         case -ERESTARTSYS:
 222                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 223                         regs->a4 = -EINTR;
 224                         break;
 225                 }
 226         /* fallthrough */
 227         case -ERESTARTNOINTR:
 228 do_restart:
 229                 regs->a4 = regs->orig_a4;
 230                 regs->pc -= 4;
 231                 break;
 232         }
 233 }
 234
 235 /*
 236  * handle the actual delivery of a signal to userspace
 237  */
 238 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs,
 239                           int syscall)
 240 {
 241         int ret;
 242
 243         /* Are we from a system call? */
 244         if (syscall) {
 245                 /* If so, check system call restarting.. */
 246                 switch (regs->a4) {
 247                 case -ERESTART_RESTARTBLOCK:
 248                 case -ERESTARTNOHAND:
 249                         regs->a4 = -EINTR;
 250                         break;
 251
 252                 case -ERESTARTSYS:
 253                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 254                                 regs->a4 = -EINTR;
 255                                 break;
 256                         }
 257
 258                         /* fallthrough */
 259                 case -ERESTARTNOINTR:
 260                         regs->a4 = regs->orig_a4;
 261                         regs->pc -= 4;
 262                 }
 263         }
 264
 265         /* Set up the stack frame */
 266         ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
 267         signal_setup_done(ret, ksig, 0);
 268 }
 269
 270 /*
 271  * handle a potential signal
 272  */
 273 static void do_signal(struct pt_regs *regs, int syscall)
 274 {
 275         struct ksignal ksig;
 276
 277         /* we want the common case to go fast, which is why we may in certain
 278          * cases get here from kernel mode */
 279         if (!user_mode(regs))
 280                 return;
 281
 282         if (get_signal(&ksig)) {
 283                 handle_signal(&ksig, regs, syscall);
 284                 return;
 285         }
 286
 287         /* did we come from a system call? */
 288         if (syscall) {
 289                 /* restart the system call - no handlers present */
 290                 switch (regs->a4) {
 291                 case -ERESTARTNOHAND:
 292                 case -ERESTARTSYS:
 293                 case -ERESTARTNOINTR:
 294                         regs->a4 = regs->orig_a4;
 295                         regs->pc -= 4;
 296                         break;
 297
 298                 case -ERESTART_RESTARTBLOCK:
 299                         regs->a4 = regs->orig_a4;
 300                         regs->b0 = __NR_restart_syscall;
 301                         regs->pc -= 4;
 302                         break;
 303                 }
 304         }
 305
 306         /* if there's no signal to deliver, we just put the saved sigmask
 307          * back */
 308         restore_saved_sigmask();
 309 }
 310
 311 /*
 312  * notification of userspace execution resumption
 313  * - triggered by current->work.notify_resume
 314  */
 315 asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags,
 316                                  int syscall)
 317 {
 318         /* deal with pending signal delivery */
 319         if (thread_info_flags & (1 << TIF_SIGPENDING))
 320                 do_signal(regs, syscall);
 321
 322         if (thread_info_flags & (1 << TIF_NOTIFY_RESUME)) {
 323                 clear_thread_flag(TIF_NOTIFY_RESUME);
 324                 tracehook_notify_resume(regs);
 325         }
 326 }