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