Pileus Git - ~andy/linux/blob - arch/um/kernel/signal.c

   1 /*
   2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <linux/module.h>
   7 #include <linux/ptrace.h>
   8 #include <linux/sched.h>
   9 #include <asm/siginfo.h>
  10 #include <asm/signal.h>
  11 #include <asm/unistd.h>
  12 #include "frame_kern.h"
  13 #include "kern_util.h"
  14
  15 EXPORT_SYMBOL(block_signals);
  16 EXPORT_SYMBOL(unblock_signals);
  17
  18 #define _S(nr) (1<<((nr)-1))
  19
  20 #define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
  21
  22 /*
  23  * OK, we're invoking a handler
  24  */
  25 static int handle_signal(struct pt_regs *regs, unsigned long signr,
  26                          struct k_sigaction *ka, siginfo_t *info,
  27                          sigset_t *oldset)
  28 {
  29         unsigned long sp;
  30         int err;
  31
  32         /* Did we come from a system call? */
  33         if (PT_REGS_SYSCALL_NR(regs) >= 0) {
  34                 /* If so, check system call restarting.. */
  35                 switch (PT_REGS_SYSCALL_RET(regs)) {
  36                 case -ERESTART_RESTARTBLOCK:
  37                 case -ERESTARTNOHAND:
  38                         PT_REGS_SYSCALL_RET(regs) = -EINTR;
  39                         break;
  40
  41                 case -ERESTARTSYS:
  42                         if (!(ka->sa.sa_flags & SA_RESTART)) {
  43                                 PT_REGS_SYSCALL_RET(regs) = -EINTR;
  44                                 break;
  45                         }
  46                 /* fallthrough */
  47                 case -ERESTARTNOINTR:
  48                         PT_REGS_RESTART_SYSCALL(regs);
  49                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  50                         break;
  51                 }
  52         }
  53
  54         sp = PT_REGS_SP(regs);
  55         if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
  56                 sp = current->sas_ss_sp + current->sas_ss_size;
  57
  58 #ifdef CONFIG_ARCH_HAS_SC_SIGNALS
  59         if (!(ka->sa.sa_flags & SA_SIGINFO))
  60                 err = setup_signal_stack_sc(sp, signr, ka, regs, oldset);
  61         else
  62 #endif
  63                 err = setup_signal_stack_si(sp, signr, ka, regs, info, oldset);
  64
  65         if (err)
  66                 force_sigsegv(signr, current);
  67         else
  68                 block_sigmask(ka, signr);
  69
  70         return err;
  71 }
  72
  73 static int kern_do_signal(struct pt_regs *regs)
  74 {
  75         struct k_sigaction ka_copy;
  76         siginfo_t info;
  77         sigset_t *oldset;
  78         int sig, handled_sig = 0;
  79
  80         if (test_thread_flag(TIF_RESTORE_SIGMASK))
  81                 oldset = &current->saved_sigmask;
  82         else
  83                 oldset = &current->blocked;
  84
  85         while ((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0) {
  86                 handled_sig = 1;
  87                 /* Whee!  Actually deliver the signal.  */
  88                 if (!handle_signal(regs, sig, &ka_copy, &info, oldset)) {
  89                         /*
  90                          * a signal was successfully delivered; the saved
  91                          * sigmask will have been stored in the signal frame,
  92                          * and will be restored by sigreturn, so we can simply
  93                          * clear the TIF_RESTORE_SIGMASK flag
  94                          */
  95                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
  96                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
  97                         break;
  98                 }
  99         }
 100
 101         /* Did we come from a system call? */
 102         if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {
 103                 /* Restart the system call - no handlers present */
 104                 switch (PT_REGS_SYSCALL_RET(regs)) {
 105                 case -ERESTARTNOHAND:
 106                 case -ERESTARTSYS:
 107                 case -ERESTARTNOINTR:
 108                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
 109                         PT_REGS_RESTART_SYSCALL(regs);
 110                         break;
 111                 case -ERESTART_RESTARTBLOCK:
 112                         PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
 113                         PT_REGS_RESTART_SYSCALL(regs);
 114                         break;
 115                 }
 116         }
 117
 118         /*
 119          * This closes a way to execute a system call on the host.  If
 120          * you set a breakpoint on a system call instruction and singlestep
 121          * from it, the tracing thread used to PTRACE_SINGLESTEP the process
 122          * rather than PTRACE_SYSCALL it, allowing the system call to execute
 123          * on the host.  The tracing thread will check this flag and
 124          * PTRACE_SYSCALL if necessary.
 125          */
 126         if (current->ptrace & PT_DTRACE)
 127                 current->thread.singlestep_syscall =
 128                         is_syscall(PT_REGS_IP(&current->thread.regs));
 129
 130         /*
 131          * if there's no signal to deliver, we just put the saved sigmask
 132          * back
 133          */
 134         if (!handled_sig && test_thread_flag(TIF_RESTORE_SIGMASK)) {
 135                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 136                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 137         }
 138         return handled_sig;
 139 }
 140
 141 int do_signal(void)
 142 {
 143         return kern_do_signal(&current->thread.regs);
 144 }
 145
 146 /*
 147  * Atomically swap in the new signal mask, and wait for a signal.
 148  */
 149 long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 150 {
 151         sigset_t blocked;
 152
 153         mask &= _BLOCKABLE;
 154         siginitset(&blocked, mask);
 155         set_current_blocked(&blocked);
 156
 157         current->state = TASK_INTERRUPTIBLE;
 158         schedule();
 159         set_thread_flag(TIF_RESTORE_SIGMASK);
 160         return -ERESTARTNOHAND;
 161 }
 162
 163 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 164 {
 165         return do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs));
 166 }