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