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 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  24
  25 /*
  26  * Do a signal return, undo the signal stack.
  27  */
  28
  29 #define RETCODE_SIZE (9 << 2)   /* 9 instructions = 36 bytes */
  30
  31 struct rt_sigframe {
  32         struct siginfo __user *pinfo;
  33         void __user *puc;
  34         struct siginfo info;
  35         struct ucontext uc;
  36         unsigned long retcode[RETCODE_SIZE >> 2];
  37 };
  38
  39 static int restore_sigcontext(struct pt_regs *regs,
  40                               struct sigcontext __user *sc)
  41 {
  42         int err = 0;
  43
  44         /* The access_ok check was done by caller, so use __get_user here */
  45 #define COPY(x)  (err |= __get_user(regs->x, &sc->sc_##x))
  46
  47         COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
  48         COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
  49         COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
  50
  51         COPY(a16); COPY(a17); COPY(a18); COPY(a19);
  52         COPY(a20); COPY(a21); COPY(a22); COPY(a23);
  53         COPY(a24); COPY(a25); COPY(a26); COPY(a27);
  54         COPY(a28); COPY(a29); COPY(a30); COPY(a31);
  55         COPY(b16); COPY(b17); COPY(b18); COPY(b19);
  56         COPY(b20); COPY(b21); COPY(b22); COPY(b23);
  57         COPY(b24); COPY(b25); COPY(b26); COPY(b27);
  58         COPY(b28); COPY(b29); COPY(b30); COPY(b31);
  59
  60         COPY(csr); COPY(pc);
  61
  62 #undef COPY
  63
  64         return err;
  65 }
  66
  67 asmlinkage int do_rt_sigreturn(struct pt_regs *regs)
  68 {
  69         struct rt_sigframe __user *frame;
  70         sigset_t set;
  71
  72         /*
  73          * Since we stacked the signal on a dword boundary,
  74          * 'sp' should be dword aligned here.  If it's
  75          * not, then the user is trying to mess with us.
  76          */
  77         if (regs->sp & 7)
  78                 goto badframe;
  79
  80         frame = (struct rt_sigframe __user *) ((unsigned long) regs->sp + 8);
  81
  82         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  83                 goto badframe;
  84         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  85                 goto badframe;
  86
  87         sigdelsetmask(&set, ~_BLOCKABLE);
  88         spin_lock_irq(&current->sighand->siglock);
  89         current->blocked = set;
  90         recalc_sigpending();
  91         spin_unlock_irq(&current->sighand->siglock);
  92
  93         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  94                 goto badframe;
  95
  96         return regs->a4;
  97
  98 badframe:
  99         force_sig(SIGSEGV, current);
 100         return 0;
 101 }
 102
 103 static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 104                             unsigned long mask)
 105 {
 106         int err = 0;
 107
 108         err |= __put_user(mask, &sc->sc_mask);
 109
 110         /* The access_ok check was done by caller, so use __put_user here */
 111 #define COPY(x) (err |= __put_user(regs->x, &sc->sc_##x))
 112
 113         COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
 114         COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
 115         COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
 116
 117         COPY(a16); COPY(a17); COPY(a18); COPY(a19);
 118         COPY(a20); COPY(a21); COPY(a22); COPY(a23);
 119         COPY(a24); COPY(a25); COPY(a26); COPY(a27);
 120         COPY(a28); COPY(a29); COPY(a30); COPY(a31);
 121         COPY(b16); COPY(b17); COPY(b18); COPY(b19);
 122         COPY(b20); COPY(b21); COPY(b22); COPY(b23);
 123         COPY(b24); COPY(b25); COPY(b26); COPY(b27);
 124         COPY(b28); COPY(b29); COPY(b30); COPY(b31);
 125
 126         COPY(csr); COPY(pc);
 127
 128 #undef COPY
 129
 130         return err;
 131 }
 132
 133 static inline void __user *get_sigframe(struct k_sigaction *ka,
 134                                         struct pt_regs *regs,
 135                                         unsigned long framesize)
 136 {
 137         unsigned long sp = regs->sp;
 138
 139         /*
 140          * This is the X/Open sanctioned signal stack switching.
 141          */
 142         if ((ka->sa.sa_flags & SA_ONSTACK) && sas_ss_flags(sp) == 0)
 143                 sp = current->sas_ss_sp + current->sas_ss_size;
 144
 145         /*
 146          * No matter what happens, 'sp' must be dword
 147          * aligned. Otherwise, nasty things will happen
 148          */
 149         return (void __user *)((sp - framesize) & ~7);
 150 }
 151
 152 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
 153                            sigset_t *set, struct pt_regs *regs)
 154 {
 155         struct rt_sigframe __user *frame;
 156         unsigned long __user *retcode;
 157         int err = 0;
 158
 159         frame = get_sigframe(ka, regs, sizeof(*frame));
 160
 161         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 162                 goto segv_and_exit;
 163
 164         err |= __put_user(&frame->info, &frame->pinfo);
 165         err |= __put_user(&frame->uc, &frame->puc);
 166         err |= copy_siginfo_to_user(&frame->info, info);
 167
 168         /* Clear all the bits of the ucontext we don't use.  */
 169         err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
 170
 171         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
 172         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 173
 174         /* Set up to return from userspace */
 175         retcode = (unsigned long __user *) &frame->retcode;
 176
 177         /* The access_ok check was done above, so use __put_user here */
 178 #define COPY(x) (err |= __put_user(x, retcode++))
 179
 180         COPY(0x0000002AUL | (__NR_rt_sigreturn << 7));
 181                                 /* MVK __NR_rt_sigreturn,B0 */
 182         COPY(0x10000000UL);     /* SWE */
 183         COPY(0x00006000UL);     /* NOP 4 */
 184         COPY(0x00006000UL);     /* NOP 4 */
 185         COPY(0x00006000UL);     /* NOP 4 */
 186         COPY(0x00006000UL);     /* NOP 4 */
 187         COPY(0x00006000UL);     /* NOP 4 */
 188         COPY(0x00006000UL);     /* NOP 4 */
 189         COPY(0x00006000UL);     /* NOP 4 */
 190
 191 #undef COPY
 192
 193         if (err)
 194                 goto segv_and_exit;
 195
 196         flush_icache_range((unsigned long) &frame->retcode,
 197                            (unsigned long) &frame->retcode + RETCODE_SIZE);
 198
 199         retcode = (unsigned long __user *) &frame->retcode;
 200
 201         /* Change user context to branch to signal handler */
 202         regs->sp = (unsigned long) frame - 8;
 203         regs->b3 = (unsigned long) retcode;
 204         regs->pc = (unsigned long) ka->sa.sa_handler;
 205
 206         /* Give the signal number to the handler */
 207         regs->a4 = signr;
 208
 209         /*
 210          * For realtime signals we must also set the second and third
 211          * arguments for the signal handler.
 212          *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 213          */
 214         regs->b4 = (unsigned long)&frame->info;
 215         regs->a6 = (unsigned long)&frame->uc;
 216
 217         return 0;
 218
 219 segv_and_exit:
 220         force_sigsegv(signr, current);
 221         return -EFAULT;
 222 }
 223
 224 static inline void
 225 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 226 {
 227         switch (regs->a4) {
 228         case -ERESTARTNOHAND:
 229                 if (!has_handler)
 230                         goto do_restart;
 231                 regs->a4 = -EINTR;
 232                 break;
 233
 234         case -ERESTARTSYS:
 235                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 236                         regs->a4 = -EINTR;
 237                         break;
 238                 }
 239         /* fallthrough */
 240         case -ERESTARTNOINTR:
 241 do_restart:
 242                 regs->a4 = regs->orig_a4;
 243                 regs->pc -= 4;
 244                 break;
 245         }
 246 }
 247
 248 /*
 249  * handle the actual delivery of a signal to userspace
 250  */
 251 static int handle_signal(int sig,
 252                          siginfo_t *info, struct k_sigaction *ka,
 253                          sigset_t *oldset, struct pt_regs *regs,
 254                          int syscall)
 255 {
 256         int ret;
 257
 258         /* Are we from a system call? */
 259         if (syscall) {
 260                 /* If so, check system call restarting.. */
 261                 switch (regs->a4) {
 262                 case -ERESTART_RESTARTBLOCK:
 263                 case -ERESTARTNOHAND:
 264                         regs->a4 = -EINTR;
 265                         break;
 266
 267                 case -ERESTARTSYS:
 268                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 269                                 regs->a4 = -EINTR;
 270                                 break;
 271                         }
 272
 273                         /* fallthrough */
 274                 case -ERESTARTNOINTR:
 275                         regs->a4 = regs->orig_a4;
 276                         regs->pc -= 4;
 277                 }
 278         }
 279
 280         /* Set up the stack frame */
 281         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 282         if (ret == 0) {
 283                 spin_lock_irq(&current->sighand->siglock);
 284                 sigorsets(&current->blocked, &current->blocked,
 285                           &ka->sa.sa_mask);
 286                 if (!(ka->sa.sa_flags & SA_NODEFER))
 287                         sigaddset(&current->blocked, sig);
 288                 recalc_sigpending();
 289                 spin_unlock_irq(&current->sighand->siglock);
 290         }
 291
 292         return ret;
 293 }
 294
 295 /*
 296  * handle a potential signal
 297  */
 298 static void do_signal(struct pt_regs *regs, int syscall)
 299 {
 300         struct k_sigaction ka;
 301         siginfo_t info;
 302         sigset_t *oldset;
 303         int signr;
 304
 305         /* we want the common case to go fast, which is why we may in certain
 306          * cases get here from kernel mode */
 307         if (!user_mode(regs))
 308                 return;
 309
 310         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 311                 oldset = &current->saved_sigmask;
 312         else
 313                 oldset = &current->blocked;
 314
 315         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 316         if (signr > 0) {
 317                 if (handle_signal(signr, &info, &ka, oldset,
 318                                   regs, syscall) == 0) {
 319                         /* a signal was successfully delivered; the saved
 320                          * sigmask will have been stored in the signal frame,
 321                          * and will be restored by sigreturn, so we can simply
 322                          * clear the TIF_RESTORE_SIGMASK flag */
 323                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 324                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 325
 326                         tracehook_signal_handler(signr, &info, &ka, regs, 0);
 327                 }
 328
 329                 return;
 330         }
 331
 332         /* did we come from a system call? */
 333         if (syscall) {
 334                 /* restart the system call - no handlers present */
 335                 switch (regs->a4) {
 336                 case -ERESTARTNOHAND:
 337                 case -ERESTARTSYS:
 338                 case -ERESTARTNOINTR:
 339                         regs->a4 = regs->orig_a4;
 340                         regs->pc -= 4;
 341                         break;
 342
 343                 case -ERESTART_RESTARTBLOCK:
 344                         regs->a4 = regs->orig_a4;
 345                         regs->b0 = __NR_restart_syscall;
 346                         regs->pc -= 4;
 347                         break;
 348                 }
 349         }
 350
 351         /* if there's no signal to deliver, we just put the saved sigmask
 352          * back */
 353         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 354                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 355                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 356         }
 357 }
 358
 359 /*
 360  * notification of userspace execution resumption
 361  * - triggered by current->work.notify_resume
 362  */
 363 asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags,
 364                                  int syscall)
 365 {
 366         /* deal with pending signal delivery */
 367         if (thread_info_flags & ((1 << TIF_SIGPENDING) |
 368                                  (1 << TIF_RESTORE_SIGMASK)))
 369                 do_signal(regs, syscall);
 370
 371         if (thread_info_flags & (1 << TIF_NOTIFY_RESUME)) {
 372                 clear_thread_flag(TIF_NOTIFY_RESUME);
 373                 tracehook_notify_resume(regs);
 374                 if (current->replacement_session_keyring)
 375                         key_replace_session_keyring();
 376         }
 377 }