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/uaccess.h>
  14 #include <linux/tracehook.h>
  15
  16 #include <asm/cacheflush.h>
  17 #include <asm/ucontext.h>
  18 #include <asm/fixed_code.h>
  19 #include <asm/syscall.h>
  20
  21 /* Location of the trace bit in SYSCFG. */
  22 #define TRACE_BITS 0x0001
  23
  24 struct fdpic_func_descriptor {
  25         unsigned long   text;
  26         unsigned long   GOT;
  27 };
  28
  29 struct rt_sigframe {
  30         int sig;
  31         struct siginfo *pinfo;
  32         void *puc;
  33         /* This is no longer needed by the kernel, but unfortunately userspace
  34          * code expects it to be there.  */
  35         char retcode[8];
  36         struct siginfo info;
  37         struct ucontext uc;
  38 };
  39
  40 static inline int
  41 rt_restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *pr0)
  42 {
  43         unsigned long usp = 0;
  44         int err = 0;
  45
  46         /* Always make any pending restarted system calls return -EINTR */
  47         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  48
  49 #define RESTORE(x) err |= __get_user(regs->x, &sc->sc_##x)
  50
  51         /* restore passed registers */
  52         RESTORE(r0); RESTORE(r1); RESTORE(r2); RESTORE(r3);
  53         RESTORE(r4); RESTORE(r5); RESTORE(r6); RESTORE(r7);
  54         RESTORE(p0); RESTORE(p1); RESTORE(p2); RESTORE(p3);
  55         RESTORE(p4); RESTORE(p5);
  56         err |= __get_user(usp, &sc->sc_usp);
  57         wrusp(usp);
  58         RESTORE(a0w); RESTORE(a1w);
  59         RESTORE(a0x); RESTORE(a1x);
  60         RESTORE(astat);
  61         RESTORE(rets);
  62         RESTORE(pc);
  63         RESTORE(retx);
  64         RESTORE(fp);
  65         RESTORE(i0); RESTORE(i1); RESTORE(i2); RESTORE(i3);
  66         RESTORE(m0); RESTORE(m1); RESTORE(m2); RESTORE(m3);
  67         RESTORE(l0); RESTORE(l1); RESTORE(l2); RESTORE(l3);
  68         RESTORE(b0); RESTORE(b1); RESTORE(b2); RESTORE(b3);
  69         RESTORE(lc0); RESTORE(lc1);
  70         RESTORE(lt0); RESTORE(lt1);
  71         RESTORE(lb0); RESTORE(lb1);
  72         RESTORE(seqstat);
  73
  74         regs->orig_p0 = -1;     /* disable syscall checks */
  75
  76         *pr0 = regs->r0;
  77         return err;
  78 }
  79
  80 asmlinkage int sys_rt_sigreturn(void)
  81 {
  82         struct pt_regs *regs = current_pt_regs();
  83         unsigned long usp = rdusp();
  84         struct rt_sigframe *frame = (struct rt_sigframe *)(usp);
  85         sigset_t set;
  86         int r0;
  87
  88         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  89                 goto badframe;
  90         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  91                 goto badframe;
  92
  93         set_current_blocked(&set);
  94
  95         if (rt_restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
  96                 goto badframe;
  97
  98         if (restore_altstack(&frame->uc.uc_stack))
  99                 goto badframe;
 100
 101         return r0;
 102
 103  badframe:
 104         force_sig(SIGSEGV, current);
 105         return 0;
 106 }
 107
 108 static inline int rt_setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs)
 109 {
 110         int err = 0;
 111
 112 #define SETUP(x) err |= __put_user(regs->x, &sc->sc_##x)
 113
 114         SETUP(r0); SETUP(r1); SETUP(r2); SETUP(r3);
 115         SETUP(r4); SETUP(r5); SETUP(r6); SETUP(r7);
 116         SETUP(p0); SETUP(p1); SETUP(p2); SETUP(p3);
 117         SETUP(p4); SETUP(p5);
 118         err |= __put_user(rdusp(), &sc->sc_usp);
 119         SETUP(a0w); SETUP(a1w);
 120         SETUP(a0x); SETUP(a1x);
 121         SETUP(astat);
 122         SETUP(rets);
 123         SETUP(pc);
 124         SETUP(retx);
 125         SETUP(fp);
 126         SETUP(i0); SETUP(i1); SETUP(i2); SETUP(i3);
 127         SETUP(m0); SETUP(m1); SETUP(m2); SETUP(m3);
 128         SETUP(l0); SETUP(l1); SETUP(l2); SETUP(l3);
 129         SETUP(b0); SETUP(b1); SETUP(b2); SETUP(b3);
 130         SETUP(lc0); SETUP(lc1);
 131         SETUP(lt0); SETUP(lt1);
 132         SETUP(lb0); SETUP(lb1);
 133         SETUP(seqstat);
 134
 135         return err;
 136 }
 137
 138 static inline void *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 139                                  size_t frame_size)
 140 {
 141         unsigned long usp;
 142
 143         /* Default to using normal stack.  */
 144         usp = rdusp();
 145
 146         /* This is the X/Open sanctioned signal stack switching.  */
 147         if (ka->sa.sa_flags & SA_ONSTACK) {
 148                 if (!on_sig_stack(usp))
 149                         usp = current->sas_ss_sp + current->sas_ss_size;
 150         }
 151         return (void *)((usp - frame_size) & -8UL);
 152 }
 153
 154 static int
 155 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t * info,
 156                sigset_t * set, struct pt_regs *regs)
 157 {
 158         struct rt_sigframe *frame;
 159         int err = 0;
 160
 161         frame = get_sigframe(ka, regs, sizeof(*frame));
 162
 163         err |= __put_user((current_thread_info()->exec_domain
 164                            && current_thread_info()->exec_domain->signal_invmap
 165                            && sig < 32
 166                            ? current_thread_info()->exec_domain->
 167                            signal_invmap[sig] : sig), &frame->sig);
 168
 169         err |= __put_user(&frame->info, &frame->pinfo);
 170         err |= __put_user(&frame->uc, &frame->puc);
 171         err |= copy_siginfo_to_user(&frame->info, info);
 172
 173         /* Create the ucontext.  */
 174         err |= __put_user(0, &frame->uc.uc_flags);
 175         err |= __put_user(0, &frame->uc.uc_link);
 176         err |= __save_altstack(&frame->uc.uc_stack, rdusp());
 177         err |= rt_setup_sigcontext(&frame->uc.uc_mcontext, regs);
 178         err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 179
 180         if (err)
 181                 return -EFAULT;
 182
 183         /* Set up registers for signal handler */
 184         if (current->personality & FDPIC_FUNCPTRS) {
 185                 struct fdpic_func_descriptor __user *funcptr =
 186                         (struct fdpic_func_descriptor *) ka->sa.sa_handler;
 187                 u32 pc, p3;
 188                 err |= __get_user(pc, &funcptr->text);
 189                 err |= __get_user(p3, &funcptr->GOT);
 190                 if (err)
 191                         return -EFAULT;
 192                 regs->pc = pc;
 193                 regs->p3 = p3;
 194         } else
 195                 regs->pc = (unsigned long)ka->sa.sa_handler;
 196         wrusp((unsigned long)frame);
 197         regs->rets = SIGRETURN_STUB;
 198
 199         regs->r0 = frame->sig;
 200         regs->r1 = (unsigned long)(&frame->info);
 201         regs->r2 = (unsigned long)(&frame->uc);
 202
 203         return 0;
 204 }
 205
 206 static inline void
 207 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 208 {
 209         switch (regs->r0) {
 210         case -ERESTARTNOHAND:
 211                 if (!has_handler)
 212                         goto do_restart;
 213                 regs->r0 = -EINTR;
 214                 break;
 215
 216         case -ERESTARTSYS:
 217                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 218                         regs->r0 = -EINTR;
 219                         break;
 220                 }
 221                 /* fallthrough */
 222         case -ERESTARTNOINTR:
 223  do_restart:
 224                 regs->p0 = regs->orig_p0;
 225                 regs->r0 = regs->orig_r0;
 226                 regs->pc -= 2;
 227                 break;
 228
 229         case -ERESTART_RESTARTBLOCK:
 230                 regs->p0 = __NR_restart_syscall;
 231                 regs->pc -= 2;
 232                 break;
 233         }
 234 }
 235
 236 /*
 237  * OK, we're invoking a handler
 238  */
 239 static void
 240 handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka,
 241               struct pt_regs *regs)
 242 {
 243         /* are we from a system call? to see pt_regs->orig_p0 */
 244         if (regs->orig_p0 >= 0)
 245                 /* If so, check system call restarting.. */
 246                 handle_restart(regs, ka, 1);
 247
 248         /* set up the stack frame */
 249         if (setup_rt_frame(sig, ka, info, sigmask_to_save(), regs) < 0)
 250                 force_sigsegv(sig, current);
 251         else
 252                 signal_delivered(sig, info, ka, regs,
 253                                 test_thread_flag(TIF_SINGLESTEP));
 254 }
 255
 256 /*
 257  * Note that 'init' is a special process: it doesn't get signals it doesn't
 258  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 259  * mistake.
 260  *
 261  * Note that we go through the signals twice: once to check the signals
 262  * that the kernel can handle, and then we build all the user-level signal
 263  * handling stack-frames in one go after that.
 264  */
 265 asmlinkage void do_signal(struct pt_regs *regs)
 266 {
 267         siginfo_t info;
 268         int signr;
 269         struct k_sigaction ka;
 270
 271         current->thread.esp0 = (unsigned long)regs;
 272
 273         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 274         if (signr > 0) {
 275                 /* Whee!  Actually deliver the signal.  */
 276                 handle_signal(signr, &info, &ka, regs);
 277                 return;
 278         }
 279
 280         /* Did we come from a system call? */
 281         if (regs->orig_p0 >= 0)
 282                 /* Restart the system call - no handlers present */
 283                 handle_restart(regs, NULL, 0);
 284
 285         /* if there's no signal to deliver, we just put the saved sigmask
 286          * back */
 287         restore_saved_sigmask();
 288 }
 289
 290 /*
 291  * notification of userspace execution resumption
 292  */
 293 asmlinkage void do_notify_resume(struct pt_regs *regs)
 294 {
 295         if (test_thread_flag(TIF_SIGPENDING))
 296                 do_signal(regs);
 297
 298         if (test_thread_flag(TIF_NOTIFY_RESUME)) {
 299                 clear_thread_flag(TIF_NOTIFY_RESUME);
 300                 tracehook_notify_resume(regs);
 301         }
 302 }
 303