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_thread_info()->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 k_sigaction *ka,
 131                                         struct pt_regs *regs,
 132                                         unsigned long framesize)
 133 {
 134         unsigned long sp = regs->sp;
 135
 136         /*
 137          * This is the X/Open sanctioned signal stack switching.
 138          */
 139         if ((ka->sa.sa_flags & SA_ONSTACK) && sas_ss_flags(sp) == 0)
 140                 sp = current->sas_ss_sp + current->sas_ss_size;
 141
 142         /*
 143          * No matter what happens, 'sp' must be dword
 144          * aligned. Otherwise, nasty things will happen
 145          */
 146         return (void __user *)((sp - framesize) & ~7);
 147 }
 148
 149 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
 150                            sigset_t *set, struct pt_regs *regs)
 151 {
 152         struct rt_sigframe __user *frame;
 153         unsigned long __user *retcode;
 154         int err = 0;
 155
 156         frame = get_sigframe(ka, regs, sizeof(*frame));
 157
 158         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 159                 goto segv_and_exit;
 160
 161         err |= __put_user(&frame->info, &frame->pinfo);
 162         err |= __put_user(&frame->uc, &frame->puc);
 163         err |= copy_siginfo_to_user(&frame->info, info);
 164
 165         /* Clear all the bits of the ucontext we don't use.  */
 166         err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
 167
 168         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
 169         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 170
 171         /* Set up to return from userspace */
 172         retcode = (unsigned long __user *) &frame->retcode;
 173
 174         /* The access_ok check was done above, so use __put_user here */
 175 #define COPY(x) (err |= __put_user(x, retcode++))
 176
 177         COPY(0x0000002AUL | (__NR_rt_sigreturn << 7));
 178                                 /* MVK __NR_rt_sigreturn,B0 */
 179         COPY(0x10000000UL);     /* SWE */
 180         COPY(0x00006000UL);     /* NOP 4 */
 181         COPY(0x00006000UL);     /* NOP 4 */
 182         COPY(0x00006000UL);     /* NOP 4 */
 183         COPY(0x00006000UL);     /* NOP 4 */
 184         COPY(0x00006000UL);     /* NOP 4 */
 185         COPY(0x00006000UL);     /* NOP 4 */
 186         COPY(0x00006000UL);     /* NOP 4 */
 187
 188 #undef COPY
 189
 190         if (err)
 191                 goto segv_and_exit;
 192
 193         flush_icache_range((unsigned long) &frame->retcode,
 194                            (unsigned long) &frame->retcode + RETCODE_SIZE);
 195
 196         retcode = (unsigned long __user *) &frame->retcode;
 197
 198         /* Change user context to branch to signal handler */
 199         regs->sp = (unsigned long) frame - 8;
 200         regs->b3 = (unsigned long) retcode;
 201         regs->pc = (unsigned long) ka->sa.sa_handler;
 202
 203         /* Give the signal number to the handler */
 204         regs->a4 = signr;
 205
 206         /*
 207          * For realtime signals we must also set the second and third
 208          * arguments for the signal handler.
 209          *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 210          */
 211         regs->b4 = (unsigned long)&frame->info;
 212         regs->a6 = (unsigned long)&frame->uc;
 213
 214         return 0;
 215
 216 segv_and_exit:
 217         force_sigsegv(signr, current);
 218         return -EFAULT;
 219 }
 220
 221 static inline void
 222 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 223 {
 224         switch (regs->a4) {
 225         case -ERESTARTNOHAND:
 226                 if (!has_handler)
 227                         goto do_restart;
 228                 regs->a4 = -EINTR;
 229                 break;
 230
 231         case -ERESTARTSYS:
 232                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 233                         regs->a4 = -EINTR;
 234                         break;
 235                 }
 236         /* fallthrough */
 237         case -ERESTARTNOINTR:
 238 do_restart:
 239                 regs->a4 = regs->orig_a4;
 240                 regs->pc -= 4;
 241                 break;
 242         }
 243 }
 244
 245 /*
 246  * handle the actual delivery of a signal to userspace
 247  */
 248 static void handle_signal(int sig,
 249                          siginfo_t *info, struct k_sigaction *ka,
 250                          struct pt_regs *regs, int syscall)
 251 {
 252         /* Are we from a system call? */
 253         if (syscall) {
 254                 /* If so, check system call restarting.. */
 255                 switch (regs->a4) {
 256                 case -ERESTART_RESTARTBLOCK:
 257                 case -ERESTARTNOHAND:
 258                         regs->a4 = -EINTR;
 259                         break;
 260
 261                 case -ERESTARTSYS:
 262                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 263                                 regs->a4 = -EINTR;
 264                                 break;
 265                         }
 266
 267                         /* fallthrough */
 268                 case -ERESTARTNOINTR:
 269                         regs->a4 = regs->orig_a4;
 270                         regs->pc -= 4;
 271                 }
 272         }
 273
 274         /* Set up the stack frame */
 275         if (setup_rt_frame(sig, ka, info, sigmask_to_save(), regs) < 0)
 276                 return;
 277         signal_delivered(sig, info, ka, regs, 0);
 278 }
 279
 280 /*
 281  * handle a potential signal
 282  */
 283 static void do_signal(struct pt_regs *regs, int syscall)
 284 {
 285         struct k_sigaction ka;
 286         siginfo_t info;
 287         int signr;
 288
 289         /* we want the common case to go fast, which is why we may in certain
 290          * cases get here from kernel mode */
 291         if (!user_mode(regs))
 292                 return;
 293
 294         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 295         if (signr > 0) {
 296                 handle_signal(signr, &info, &ka, regs, syscall);
 297                 return;
 298         }
 299
 300         /* did we come from a system call? */
 301         if (syscall) {
 302                 /* restart the system call - no handlers present */
 303                 switch (regs->a4) {
 304                 case -ERESTARTNOHAND:
 305                 case -ERESTARTSYS:
 306                 case -ERESTARTNOINTR:
 307                         regs->a4 = regs->orig_a4;
 308                         regs->pc -= 4;
 309                         break;
 310
 311                 case -ERESTART_RESTARTBLOCK:
 312                         regs->a4 = regs->orig_a4;
 313                         regs->b0 = __NR_restart_syscall;
 314                         regs->pc -= 4;
 315                         break;
 316                 }
 317         }
 318
 319         /* if there's no signal to deliver, we just put the saved sigmask
 320          * back */
 321         restore_saved_sigmask();
 322 }
 323
 324 /*
 325  * notification of userspace execution resumption
 326  * - triggered by current->work.notify_resume
 327  */
 328 asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags,
 329                                  int syscall)
 330 {
 331         /* deal with pending signal delivery */
 332         if (thread_info_flags & (1 << TIF_SIGPENDING))
 333                 do_signal(regs, syscall);
 334
 335         if (thread_info_flags & (1 << TIF_NOTIFY_RESUME)) {
 336                 clear_thread_flag(TIF_NOTIFY_RESUME);
 337                 tracehook_notify_resume(regs);
 338         }
 339 }