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->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 ksignal *ksig,
 139                                  size_t frame_size)
 140 {
 141         unsigned long usp = sigsp(rdusp(), ksig);
 142
 143         return (void *)((usp - frame_size) & -8UL);
 144 }
 145
 146 static int
 147 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 148 {
 149         struct rt_sigframe *frame;
 150         int err = 0;
 151
 152         frame = get_sigframe(ksig, sizeof(*frame));
 153
 154         err |= __put_user(ksig->sig, &frame->sig);
 155
 156         err |= __put_user(&frame->info, &frame->pinfo);
 157         err |= __put_user(&frame->uc, &frame->puc);
 158         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 159
 160         /* Create the ucontext.  */
 161         err |= __put_user(0, &frame->uc.uc_flags);
 162         err |= __put_user(0, &frame->uc.uc_link);
 163         err |= __save_altstack(&frame->uc.uc_stack, rdusp());
 164         err |= rt_setup_sigcontext(&frame->uc.uc_mcontext, regs);
 165         err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 166
 167         if (err)
 168                 return -EFAULT;
 169
 170         /* Set up registers for signal handler */
 171         if (current->personality & FDPIC_FUNCPTRS) {
 172                 struct fdpic_func_descriptor __user *funcptr =
 173                         (struct fdpic_func_descriptor *) ksig->ka.sa.sa_handler;
 174                 u32 pc, p3;
 175                 err |= __get_user(pc, &funcptr->text);
 176                 err |= __get_user(p3, &funcptr->GOT);
 177                 if (err)
 178                         return -EFAULT;
 179                 regs->pc = pc;
 180                 regs->p3 = p3;
 181         } else
 182                 regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
 183         wrusp((unsigned long)frame);
 184         regs->rets = SIGRETURN_STUB;
 185
 186         regs->r0 = frame->sig;
 187         regs->r1 = (unsigned long)(&frame->info);
 188         regs->r2 = (unsigned long)(&frame->uc);
 189
 190         return 0;
 191 }
 192
 193 static inline void
 194 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 195 {
 196         switch (regs->r0) {
 197         case -ERESTARTNOHAND:
 198                 if (!has_handler)
 199                         goto do_restart;
 200                 regs->r0 = -EINTR;
 201                 break;
 202
 203         case -ERESTARTSYS:
 204                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 205                         regs->r0 = -EINTR;
 206                         break;
 207                 }
 208                 /* fallthrough */
 209         case -ERESTARTNOINTR:
 210  do_restart:
 211                 regs->p0 = regs->orig_p0;
 212                 regs->r0 = regs->orig_r0;
 213                 regs->pc -= 2;
 214                 break;
 215
 216         case -ERESTART_RESTARTBLOCK:
 217                 regs->p0 = __NR_restart_syscall;
 218                 regs->pc -= 2;
 219                 break;
 220         }
 221 }
 222
 223 /*
 224  * OK, we're invoking a handler
 225  */
 226 static void
 227 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 228 {
 229         int ret;
 230
 231         /* are we from a system call? to see pt_regs->orig_p0 */
 232         if (regs->orig_p0 >= 0)
 233                 /* If so, check system call restarting.. */
 234                 handle_restart(regs, &ksig->ka, 1);
 235
 236         /* set up the stack frame */
 237         ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
 238
 239         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 240 }
 241
 242 /*
 243  * Note that 'init' is a special process: it doesn't get signals it doesn't
 244  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 245  * mistake.
 246  *
 247  * Note that we go through the signals twice: once to check the signals
 248  * that the kernel can handle, and then we build all the user-level signal
 249  * handling stack-frames in one go after that.
 250  */
 251 asmlinkage void do_signal(struct pt_regs *regs)
 252 {
 253         struct ksignal ksig;
 254
 255         current->thread.esp0 = (unsigned long)regs;
 256
 257         if (get_signal(&ksig)) {
 258                 /* Whee!  Actually deliver the signal.  */
 259                 handle_signal(&ksig, regs);
 260                 return;
 261         }
 262
 263         /* Did we come from a system call? */
 264         if (regs->orig_p0 >= 0)
 265                 /* Restart the system call - no handlers present */
 266                 handle_restart(regs, NULL, 0);
 267
 268         /* if there's no signal to deliver, we just put the saved sigmask
 269          * back */
 270         restore_saved_sigmask();
 271 }
 272
 273 /*
 274  * notification of userspace execution resumption
 275  */
 276 asmlinkage void do_notify_resume(struct pt_regs *regs)
 277 {
 278         if (test_thread_flag(TIF_SIGPENDING))
 279                 do_signal(regs);
 280
 281         if (test_thread_flag(TIF_NOTIFY_RESUME)) {
 282                 clear_thread_flag(TIF_NOTIFY_RESUME);
 283                 tracehook_notify_resume(regs);
 284         }
 285 }
 286