arch/blackfin/kernel/signal.c

   1 /*
   2  * Copyright 2004-2009 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
  21 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  22
  23 /* Location of the trace bit in SYSCFG. */
  24 #define TRACE_BITS 0x0001
  25
  26 struct fdpic_func_descriptor {
  27         unsigned long   text;
  28         unsigned long   GOT;
  29 };
  30
  31 struct rt_sigframe {
  32         int sig;
  33         struct siginfo *pinfo;
  34         void *puc;
  35         /* This is no longer needed by the kernel, but unfortunately userspace
  36          * code expects it to be there.  */
  37         char retcode[8];
  38         struct siginfo info;
  39         struct ucontext uc;
  40 };
  41
  42 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
  43 {
  44         return do_sigaltstack(uss, uoss, rdusp());
  45 }
  46
  47 static inline int
  48 rt_restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *pr0)
  49 {
  50         unsigned long usp = 0;
  51         int err = 0;
  52
  53 #define RESTORE(x) err |= __get_user(regs->x, &sc->sc_##x)
  54
  55         /* restore passed registers */
  56         RESTORE(r0); RESTORE(r1); RESTORE(r2); RESTORE(r3);
  57         RESTORE(r4); RESTORE(r5); RESTORE(r6); RESTORE(r7);
  58         RESTORE(p0); RESTORE(p1); RESTORE(p2); RESTORE(p3);
  59         RESTORE(p4); RESTORE(p5);
  60         err |= __get_user(usp, &sc->sc_usp);
  61         wrusp(usp);
  62         RESTORE(a0w); RESTORE(a1w);
  63         RESTORE(a0x); RESTORE(a1x);
  64         RESTORE(astat);
  65         RESTORE(rets);
  66         RESTORE(pc);
  67         RESTORE(retx);
  68         RESTORE(fp);
  69         RESTORE(i0); RESTORE(i1); RESTORE(i2); RESTORE(i3);
  70         RESTORE(m0); RESTORE(m1); RESTORE(m2); RESTORE(m3);
  71         RESTORE(l0); RESTORE(l1); RESTORE(l2); RESTORE(l3);
  72         RESTORE(b0); RESTORE(b1); RESTORE(b2); RESTORE(b3);
  73         RESTORE(lc0); RESTORE(lc1);
  74         RESTORE(lt0); RESTORE(lt1);
  75         RESTORE(lb0); RESTORE(lb1);
  76         RESTORE(seqstat);
  77
  78         regs->orig_p0 = -1;     /* disable syscall checks */
  79
  80         *pr0 = regs->r0;
  81         return err;
  82 }
  83
  84 asmlinkage int do_rt_sigreturn(unsigned long __unused)
  85 {
  86         struct pt_regs *regs = (struct pt_regs *)__unused;
  87         unsigned long usp = rdusp();
  88         struct rt_sigframe *frame = (struct rt_sigframe *)(usp);
  89         sigset_t set;
  90         int r0;
  91
  92         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  93                 goto badframe;
  94         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  95                 goto badframe;
  96
  97         sigdelsetmask(&set, ~_BLOCKABLE);
  98         spin_lock_irq(&current->sighand->siglock);
  99         current->blocked = set;
 100         recalc_sigpending();
 101         spin_unlock_irq(&current->sighand->siglock);
 102
 103         if (rt_restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
 104                 goto badframe;
 105
 106         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->usp) == -EFAULT)
 107                 goto badframe;
 108
 109         return r0;
 110
 111  badframe:
 112         force_sig(SIGSEGV, current);
 113         return 0;
 114 }
 115
 116 static inline int rt_setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs)
 117 {
 118         int err = 0;
 119
 120 #define SETUP(x) err |= __put_user(regs->x, &sc->sc_##x)
 121
 122         SETUP(r0); SETUP(r1); SETUP(r2); SETUP(r3);
 123         SETUP(r4); SETUP(r5); SETUP(r6); SETUP(r7);
 124         SETUP(p0); SETUP(p1); SETUP(p2); SETUP(p3);
 125         SETUP(p4); SETUP(p5);
 126         err |= __put_user(rdusp(), &sc->sc_usp);
 127         SETUP(a0w); SETUP(a1w);
 128         SETUP(a0x); SETUP(a1x);
 129         SETUP(astat);
 130         SETUP(rets);
 131         SETUP(pc);
 132         SETUP(retx);
 133         SETUP(fp);
 134         SETUP(i0); SETUP(i1); SETUP(i2); SETUP(i3);
 135         SETUP(m0); SETUP(m1); SETUP(m2); SETUP(m3);
 136         SETUP(l0); SETUP(l1); SETUP(l2); SETUP(l3);
 137         SETUP(b0); SETUP(b1); SETUP(b2); SETUP(b3);
 138         SETUP(lc0); SETUP(lc1);
 139         SETUP(lt0); SETUP(lt1);
 140         SETUP(lb0); SETUP(lb1);
 141         SETUP(seqstat);
 142
 143         return err;
 144 }
 145
 146 static inline void *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 147                                  size_t frame_size)
 148 {
 149         unsigned long usp;
 150
 151         /* Default to using normal stack.  */
 152         usp = rdusp();
 153
 154         /* This is the X/Open sanctioned signal stack switching.  */
 155         if (ka->sa.sa_flags & SA_ONSTACK) {
 156                 if (!on_sig_stack(usp))
 157                         usp = current->sas_ss_sp + current->sas_ss_size;
 158         }
 159         return (void *)((usp - frame_size) & -8UL);
 160 }
 161
 162 static int
 163 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t * info,
 164                sigset_t * set, struct pt_regs *regs)
 165 {
 166         struct rt_sigframe *frame;
 167         int err = 0;
 168
 169         frame = get_sigframe(ka, regs, sizeof(*frame));
 170
 171         err |= __put_user((current_thread_info()->exec_domain
 172                            && current_thread_info()->exec_domain->signal_invmap
 173                            && sig < 32
 174                            ? current_thread_info()->exec_domain->
 175                            signal_invmap[sig] : sig), &frame->sig);
 176
 177         err |= __put_user(&frame->info, &frame->pinfo);
 178         err |= __put_user(&frame->uc, &frame->puc);
 179         err |= copy_siginfo_to_user(&frame->info, info);
 180
 181         /* Create the ucontext.  */
 182         err |= __put_user(0, &frame->uc.uc_flags);
 183         err |= __put_user(0, &frame->uc.uc_link);
 184         err |=
 185             __put_user((void *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 186         err |= __put_user(sas_ss_flags(rdusp()), &frame->uc.uc_stack.ss_flags);
 187         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 188         err |= rt_setup_sigcontext(&frame->uc.uc_mcontext, regs);
 189         err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 190
 191         if (err)
 192                 goto give_sigsegv;
 193
 194         /* Set up registers for signal handler */
 195         wrusp((unsigned long)frame);
 196         if (current->personality & FDPIC_FUNCPTRS) {
 197                 struct fdpic_func_descriptor __user *funcptr =
 198                         (struct fdpic_func_descriptor *) ka->sa.sa_handler;
 199                 __get_user(regs->pc, &funcptr->text);
 200                 __get_user(regs->p3, &funcptr->GOT);
 201         } else
 202                 regs->pc = (unsigned long)ka->sa.sa_handler;
 203         regs->rets = SIGRETURN_STUB;
 204
 205         regs->r0 = frame->sig;
 206         regs->r1 = (unsigned long)(&frame->info);
 207         regs->r2 = (unsigned long)(&frame->uc);
 208
 209         /*
 210          * Clear the trace flag when entering the signal handler, but
 211          * notify any tracer that was single-stepping it. The tracer
 212          * may want to single-step inside the handler too.
 213          */
 214         if (regs->syscfg & TRACE_BITS) {
 215                 regs->syscfg &= ~TRACE_BITS;
 216                 ptrace_notify(SIGTRAP);
 217         }
 218
 219         return 0;
 220
 221  give_sigsegv:
 222         if (sig == SIGSEGV)
 223                 ka->sa.sa_handler = SIG_DFL;
 224         force_sig(SIGSEGV, current);
 225         return -EFAULT;
 226 }
 227
 228 static inline void
 229 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 230 {
 231         switch (regs->r0) {
 232         case -ERESTARTNOHAND:
 233                 if (!has_handler)
 234                         goto do_restart;
 235                 regs->r0 = -EINTR;
 236                 break;
 237
 238         case -ERESTARTSYS:
 239                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 240                         regs->r0 = -EINTR;
 241                         break;
 242                 }
 243                 /* fallthrough */
 244         case -ERESTARTNOINTR:
 245  do_restart:
 246                 regs->p0 = regs->orig_p0;
 247                 regs->r0 = regs->orig_r0;
 248                 regs->pc -= 2;
 249                 break;
 250         }
 251 }
 252
 253 /*
 254  * OK, we're invoking a handler
 255  */
 256 static int
 257 handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka,
 258               sigset_t *oldset, struct pt_regs *regs)
 259 {
 260         int ret;
 261
 262         /* are we from a system call? to see pt_regs->orig_p0 */
 263         if (regs->orig_p0 >= 0)
 264                 /* If so, check system call restarting.. */
 265                 handle_restart(regs, ka, 1);
 266
 267         /* set up the stack frame */
 268         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 269
 270         if (ret == 0) {
 271                 spin_lock_irq(&current->sighand->siglock);
 272                 sigorsets(&current->blocked, &current->blocked,
 273                           &ka->sa.sa_mask);
 274                 if (!(ka->sa.sa_flags & SA_NODEFER))
 275                         sigaddset(&current->blocked, sig);
 276                 recalc_sigpending();
 277                 spin_unlock_irq(&current->sighand->siglock);
 278         }
 279         return ret;
 280 }
 281
 282 /*
 283  * Note that 'init' is a special process: it doesn't get signals it doesn't
 284  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 285  * mistake.
 286  *
 287  * Note that we go through the signals twice: once to check the signals
 288  * that the kernel can handle, and then we build all the user-level signal
 289  * handling stack-frames in one go after that.
 290  */
 291 asmlinkage void do_signal(struct pt_regs *regs)
 292 {
 293         siginfo_t info;
 294         int signr;
 295         struct k_sigaction ka;
 296         sigset_t *oldset;
 297
 298         current->thread.esp0 = (unsigned long)regs;
 299
 300         if (try_to_freeze())
 301                 goto no_signal;
 302
 303         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 304                 oldset = &current->saved_sigmask;
 305         else
 306                 oldset = &current->blocked;
 307
 308         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 309         if (signr > 0) {
 310                 /* Whee!  Actually deliver the signal.  */
 311                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 312                         /* a signal was successfully delivered; the saved
 313                          * sigmask will have been stored in the signal frame,
 314                          * and will be restored by sigreturn, so we can simply
 315                          * clear the TIF_RESTORE_SIGMASK flag */
 316                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 317                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 318                 }
 319
 320                 return;
 321         }
 322
 323  no_signal:
 324         /* Did we come from a system call? */
 325         if (regs->orig_p0 >= 0)
 326                 /* Restart the system call - no handlers present */
 327                 handle_restart(regs, NULL, 0);
 328
 329         /* if there's no signal to deliver, we just put the saved sigmask
 330          * back */
 331         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 332                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 333                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 334         }
 335 }
 336
 337 /*
 338  * notification of userspace execution resumption
 339  */
 340 asmlinkage void do_notify_resume(struct pt_regs *regs)
 341 {
 342         if (test_thread_flag(TIF_SIGPENDING) || test_thread_flag(TIF_RESTORE_SIGMASK))
 343                 do_signal(regs);
 344
 345         if (test_thread_flag(TIF_NOTIFY_RESUME)) {
 346                 clear_thread_flag(TIF_NOTIFY_RESUME);
 347                 tracehook_notify_resume(regs);
 348                 if (current->replacement_session_keyring)
 349                         key_replace_session_keyring();
 350         }
 351 }
 352