arch/blackfin/kernel/signal.c

   1 /*
   2  * Copyright 2004-2010 Analog Devices Inc.
   3  *
   4  * Licensed under the GPL-2 or later
   5  */
   6
   7 #include <linux/signal.h>
   8 #include <linux/syscalls.h>
   9 #include <linux/ptrace.h>
  10 #include <linux/tty.h>
  11 #include <linux/personality.h>
  12 #include <linux/binfmts.h>
  13 #include <linux/freezer.h>
  14 #include <linux/uaccess.h>
  15 #include <linux/tracehook.h>
  16
  17 #include <asm/cacheflush.h>
  18 #include <asm/ucontext.h>
  19 #include <asm/fixed_code.h>
  20 #include <asm/syscall.h>
  21
  22 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  23
  24 /* Location of the trace bit in SYSCFG. */
  25 #define TRACE_BITS 0x0001
  26
  27 struct fdpic_func_descriptor {
  28         unsigned long   text;
  29         unsigned long   GOT;
  30 };
  31
  32 struct rt_sigframe {
  33         int sig;
  34         struct siginfo *pinfo;
  35         void *puc;
  36         /* This is no longer needed by the kernel, but unfortunately userspace
  37          * code expects it to be there.  */
  38         char retcode[8];
  39         struct siginfo info;
  40         struct ucontext uc;
  41 };
  42
  43 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
  44 {
  45         return do_sigaltstack(uss, uoss, rdusp());
  46 }
  47
  48 static inline int
  49 rt_restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *pr0)
  50 {
  51         unsigned long usp = 0;
  52         int err = 0;
  53
  54         /* Always make any pending restarted system calls return -EINTR */
  55         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  56
  57 #define RESTORE(x) err |= __get_user(regs->x, &sc->sc_##x)
  58
  59         /* restore passed registers */
  60         RESTORE(r0); RESTORE(r1); RESTORE(r2); RESTORE(r3);
  61         RESTORE(r4); RESTORE(r5); RESTORE(r6); RESTORE(r7);
  62         RESTORE(p0); RESTORE(p1); RESTORE(p2); RESTORE(p3);
  63         RESTORE(p4); RESTORE(p5);
  64         err |= __get_user(usp, &sc->sc_usp);
  65         wrusp(usp);
  66         RESTORE(a0w); RESTORE(a1w);
  67         RESTORE(a0x); RESTORE(a1x);
  68         RESTORE(astat);
  69         RESTORE(rets);
  70         RESTORE(pc);
  71         RESTORE(retx);
  72         RESTORE(fp);
  73         RESTORE(i0); RESTORE(i1); RESTORE(i2); RESTORE(i3);
  74         RESTORE(m0); RESTORE(m1); RESTORE(m2); RESTORE(m3);
  75         RESTORE(l0); RESTORE(l1); RESTORE(l2); RESTORE(l3);
  76         RESTORE(b0); RESTORE(b1); RESTORE(b2); RESTORE(b3);
  77         RESTORE(lc0); RESTORE(lc1);
  78         RESTORE(lt0); RESTORE(lt1);
  79         RESTORE(lb0); RESTORE(lb1);
  80         RESTORE(seqstat);
  81
  82         regs->orig_p0 = -1;     /* disable syscall checks */
  83
  84         *pr0 = regs->r0;
  85         return err;
  86 }
  87
  88 asmlinkage int do_rt_sigreturn(unsigned long __unused)
  89 {
  90         struct pt_regs *regs = (struct pt_regs *)__unused;
  91         unsigned long usp = rdusp();
  92         struct rt_sigframe *frame = (struct rt_sigframe *)(usp);
  93         sigset_t set;
  94         int r0;
  95
  96         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  97                 goto badframe;
  98         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  99                 goto badframe;
 100
 101         sigdelsetmask(&set, ~_BLOCKABLE);
 102         set_current_blocked(&set);
 103
 104         if (rt_restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
 105                 goto badframe;
 106
 107         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->usp) == -EFAULT)
 108                 goto badframe;
 109
 110         return r0;
 111
 112  badframe:
 113         force_sig(SIGSEGV, current);
 114         return 0;
 115 }
 116
 117 static inline int rt_setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs)
 118 {
 119         int err = 0;
 120
 121 #define SETUP(x) err |= __put_user(regs->x, &sc->sc_##x)
 122
 123         SETUP(r0); SETUP(r1); SETUP(r2); SETUP(r3);
 124         SETUP(r4); SETUP(r5); SETUP(r6); SETUP(r7);
 125         SETUP(p0); SETUP(p1); SETUP(p2); SETUP(p3);
 126         SETUP(p4); SETUP(p5);
 127         err |= __put_user(rdusp(), &sc->sc_usp);
 128         SETUP(a0w); SETUP(a1w);
 129         SETUP(a0x); SETUP(a1x);
 130         SETUP(astat);
 131         SETUP(rets);
 132         SETUP(pc);
 133         SETUP(retx);
 134         SETUP(fp);
 135         SETUP(i0); SETUP(i1); SETUP(i2); SETUP(i3);
 136         SETUP(m0); SETUP(m1); SETUP(m2); SETUP(m3);
 137         SETUP(l0); SETUP(l1); SETUP(l2); SETUP(l3);
 138         SETUP(b0); SETUP(b1); SETUP(b2); SETUP(b3);
 139         SETUP(lc0); SETUP(lc1);
 140         SETUP(lt0); SETUP(lt1);
 141         SETUP(lb0); SETUP(lb1);
 142         SETUP(seqstat);
 143
 144         return err;
 145 }
 146
 147 static inline void *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 148                                  size_t frame_size)
 149 {
 150         unsigned long usp;
 151
 152         /* Default to using normal stack.  */
 153         usp = rdusp();
 154
 155         /* This is the X/Open sanctioned signal stack switching.  */
 156         if (ka->sa.sa_flags & SA_ONSTACK) {
 157                 if (!on_sig_stack(usp))
 158                         usp = current->sas_ss_sp + current->sas_ss_size;
 159         }
 160         return (void *)((usp - frame_size) & -8UL);
 161 }
 162
 163 static int
 164 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t * info,
 165                sigset_t * set, struct pt_regs *regs)
 166 {
 167         struct rt_sigframe *frame;
 168         int err = 0;
 169
 170         frame = get_sigframe(ka, regs, sizeof(*frame));
 171
 172         err |= __put_user((current_thread_info()->exec_domain
 173                            && current_thread_info()->exec_domain->signal_invmap
 174                            && sig < 32
 175                            ? current_thread_info()->exec_domain->
 176                            signal_invmap[sig] : sig), &frame->sig);
 177
 178         err |= __put_user(&frame->info, &frame->pinfo);
 179         err |= __put_user(&frame->uc, &frame->puc);
 180         err |= copy_siginfo_to_user(&frame->info, info);
 181
 182         /* Create the ucontext.  */
 183         err |= __put_user(0, &frame->uc.uc_flags);
 184         err |= __put_user(0, &frame->uc.uc_link);
 185         err |=
 186             __put_user((void *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 187         err |= __put_user(sas_ss_flags(rdusp()), &frame->uc.uc_stack.ss_flags);
 188         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 189         err |= rt_setup_sigcontext(&frame->uc.uc_mcontext, regs);
 190         err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 191
 192         if (err)
 193                 goto give_sigsegv;
 194
 195         /* Set up registers for signal handler */
 196         wrusp((unsigned long)frame);
 197         if (current->personality & FDPIC_FUNCPTRS) {
 198                 struct fdpic_func_descriptor __user *funcptr =
 199                         (struct fdpic_func_descriptor *) ka->sa.sa_handler;
 200                 __get_user(regs->pc, &funcptr->text);
 201                 __get_user(regs->p3, &funcptr->GOT);
 202         } else
 203                 regs->pc = (unsigned long)ka->sa.sa_handler;
 204         regs->rets = SIGRETURN_STUB;
 205
 206         regs->r0 = frame->sig;
 207         regs->r1 = (unsigned long)(&frame->info);
 208         regs->r2 = (unsigned long)(&frame->uc);
 209
 210         return 0;
 211
 212  give_sigsegv:
 213         force_sigsegv(sig, current);
 214         return -EFAULT;
 215 }
 216
 217 static inline void
 218 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 219 {
 220         switch (regs->r0) {
 221         case -ERESTARTNOHAND:
 222                 if (!has_handler)
 223                         goto do_restart;
 224                 regs->r0 = -EINTR;
 225                 break;
 226
 227         case -ERESTARTSYS:
 228                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 229                         regs->r0 = -EINTR;
 230                         break;
 231                 }
 232                 /* fallthrough */
 233         case -ERESTARTNOINTR:
 234  do_restart:
 235                 regs->p0 = regs->orig_p0;
 236                 regs->r0 = regs->orig_r0;
 237                 regs->pc -= 2;
 238                 break;
 239
 240         case -ERESTART_RESTARTBLOCK:
 241                 regs->p0 = __NR_restart_syscall;
 242                 regs->pc -= 2;
 243                 break;
 244         }
 245 }
 246
 247 /*
 248  * OK, we're invoking a handler
 249  */
 250 static int
 251 handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka,
 252               sigset_t *oldset, struct pt_regs *regs)
 253 {
 254         int ret;
 255
 256         /* are we from a system call? to see pt_regs->orig_p0 */
 257         if (regs->orig_p0 >= 0)
 258                 /* If so, check system call restarting.. */
 259                 handle_restart(regs, ka, 1);
 260
 261         /* set up the stack frame */
 262         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 263
 264         if (ret == 0)
 265                 block_sigmask(ka, sig);
 266
 267         return ret;
 268 }
 269
 270 /*
 271  * Note that 'init' is a special process: it doesn't get signals it doesn't
 272  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 273  * mistake.
 274  *
 275  * Note that we go through the signals twice: once to check the signals
 276  * that the kernel can handle, and then we build all the user-level signal
 277  * handling stack-frames in one go after that.
 278  */
 279 asmlinkage void do_signal(struct pt_regs *regs)
 280 {
 281         siginfo_t info;
 282         int signr;
 283         struct k_sigaction ka;
 284         sigset_t *oldset;
 285
 286         current->thread.esp0 = (unsigned long)regs;
 287
 288         if (try_to_freeze())
 289                 goto no_signal;
 290
 291         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 292                 oldset = &current->saved_sigmask;
 293         else
 294                 oldset = &current->blocked;
 295
 296         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 297         if (signr > 0) {
 298                 /* Whee!  Actually deliver the signal.  */
 299                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 300                         /* a signal was successfully delivered; the saved
 301                          * sigmask will have been stored in the signal frame,
 302                          * and will be restored by sigreturn, so we can simply
 303                          * clear the TIF_RESTORE_SIGMASK flag */
 304                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 305                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 306
 307                         tracehook_signal_handler(signr, &info, &ka, regs,
 308                                 test_thread_flag(TIF_SINGLESTEP));
 309                 }
 310
 311                 return;
 312         }
 313
 314  no_signal:
 315         /* Did we come from a system call? */
 316         if (regs->orig_p0 >= 0)
 317                 /* Restart the system call - no handlers present */
 318                 handle_restart(regs, NULL, 0);
 319
 320         /* if there's no signal to deliver, we just put the saved sigmask
 321          * back */
 322         restore_saved_sigmask();
 323 }
 324
 325 /*
 326  * notification of userspace execution resumption
 327  */
 328 asmlinkage void do_notify_resume(struct pt_regs *regs)
 329 {
 330         if (test_thread_flag(TIF_SIGPENDING) || test_thread_flag(TIF_RESTORE_SIGMASK))
 331                 do_signal(regs);
 332
 333         if (test_thread_flag(TIF_NOTIFY_RESUME)) {
 334                 clear_thread_flag(TIF_NOTIFY_RESUME);
 335                 tracehook_notify_resume(regs);
 336         }
 337 }
 338