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 /*
  19  * OK, we're invoking a handler
  20  */
  21 static void handle_signal(struct pt_regs *regs, unsigned long signr,
  22                          struct k_sigaction *ka, siginfo_t *info)
  23 {
  24         sigset_t *oldset = sigmask_to_save();
  25         unsigned long sp;
  26         int err;
  27
  28         /* Did we come from a system call? */
  29         if (PT_REGS_SYSCALL_NR(regs) >= 0) {
  30                 /* If so, check system call restarting.. */
  31                 switch (PT_REGS_SYSCALL_RET(regs)) {
  32                 case -ERESTART_RESTARTBLOCK:
  33                 case -ERESTARTNOHAND:
  34                         PT_REGS_SYSCALL_RET(regs) = -EINTR;
  35                         break;
  36
  37                 case -ERESTARTSYS:
  38                         if (!(ka->sa.sa_flags & SA_RESTART)) {
  39                                 PT_REGS_SYSCALL_RET(regs) = -EINTR;
  40                                 break;
  41                         }
  42                 /* fallthrough */
  43                 case -ERESTARTNOINTR:
  44                         PT_REGS_RESTART_SYSCALL(regs);
  45                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  46                         break;
  47                 }
  48         }
  49
  50         sp = PT_REGS_SP(regs);
  51         if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
  52                 sp = current->sas_ss_sp + current->sas_ss_size;
  53
  54 #ifdef CONFIG_ARCH_HAS_SC_SIGNALS
  55         if (!(ka->sa.sa_flags & SA_SIGINFO))
  56                 err = setup_signal_stack_sc(sp, signr, ka, regs, oldset);
  57         else
  58 #endif
  59                 err = setup_signal_stack_si(sp, signr, ka, regs, info, oldset);
  60
  61         if (err)
  62                 force_sigsegv(signr, current);
  63         else
  64                 signal_delivered(signr, info, ka, regs, 0);
  65 }
  66
  67 static int kern_do_signal(struct pt_regs *regs)
  68 {
  69         struct k_sigaction ka_copy;
  70         siginfo_t info;
  71         int sig, handled_sig = 0;
  72
  73         while ((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0) {
  74                 handled_sig = 1;
  75                 /* Whee!  Actually deliver the signal.  */
  76                 handle_signal(regs, sig, &ka_copy, &info);
  77         }
  78
  79         /* Did we come from a system call? */
  80         if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {
  81                 /* Restart the system call - no handlers present */
  82                 switch (PT_REGS_SYSCALL_RET(regs)) {
  83                 case -ERESTARTNOHAND:
  84                 case -ERESTARTSYS:
  85                 case -ERESTARTNOINTR:
  86                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  87                         PT_REGS_RESTART_SYSCALL(regs);
  88                         break;
  89                 case -ERESTART_RESTARTBLOCK:
  90                         PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
  91                         PT_REGS_RESTART_SYSCALL(regs);
  92                         break;
  93                 }
  94         }
  95
  96         /*
  97          * This closes a way to execute a system call on the host.  If
  98          * you set a breakpoint on a system call instruction and singlestep
  99          * from it, the tracing thread used to PTRACE_SINGLESTEP the process
 100          * rather than PTRACE_SYSCALL it, allowing the system call to execute
 101          * on the host.  The tracing thread will check this flag and
 102          * PTRACE_SYSCALL if necessary.
 103          */
 104         if (current->ptrace & PT_DTRACE)
 105                 current->thread.singlestep_syscall =
 106                         is_syscall(PT_REGS_IP(&current->thread.regs));
 107
 108         /*
 109          * if there's no signal to deliver, we just put the saved sigmask
 110          * back
 111          */
 112         if (!handled_sig)
 113                 restore_saved_sigmask();
 114         return handled_sig;
 115 }
 116
 117 int do_signal(void)
 118 {
 119         return kern_do_signal(&current->thread.regs);
 120 }
 121
 122 /*
 123  * Atomically swap in the new signal mask, and wait for a signal.
 124  */
 125 long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 126 {
 127         sigset_t blocked;
 128         siginitset(&blocked, mask);
 129         return sigsuspend(&blocked);
 130 }
 131
 132 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 133 {
 134         return do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs));
 135 }