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         int singlestep = 0;
  26         unsigned long sp;
  27         int err;
  28
  29         if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
  30                 singlestep = 1;
  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                 signal_delivered(signr, info, ka, regs, singlestep);
  69 }
  70
  71 static int kern_do_signal(struct pt_regs *regs)
  72 {
  73         struct k_sigaction ka_copy;
  74         siginfo_t info;
  75         int sig, handled_sig = 0;
  76
  77         while ((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0) {
  78                 handled_sig = 1;
  79                 /* Whee!  Actually deliver the signal.  */
  80                 handle_signal(regs, sig, &ka_copy, &info);
  81         }
  82
  83         /* Did we come from a system call? */
  84         if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {
  85                 /* Restart the system call - no handlers present */
  86                 switch (PT_REGS_SYSCALL_RET(regs)) {
  87                 case -ERESTARTNOHAND:
  88                 case -ERESTARTSYS:
  89                 case -ERESTARTNOINTR:
  90                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  91                         PT_REGS_RESTART_SYSCALL(regs);
  92                         break;
  93                 case -ERESTART_RESTARTBLOCK:
  94                         PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
  95                         PT_REGS_RESTART_SYSCALL(regs);
  96                         break;
  97                 }
  98         }
  99
 100         /*
 101          * This closes a way to execute a system call on the host.  If
 102          * you set a breakpoint on a system call instruction and singlestep
 103          * from it, the tracing thread used to PTRACE_SINGLESTEP the process
 104          * rather than PTRACE_SYSCALL it, allowing the system call to execute
 105          * on the host.  The tracing thread will check this flag and
 106          * PTRACE_SYSCALL if necessary.
 107          */
 108         if (current->ptrace & PT_DTRACE)
 109                 current->thread.singlestep_syscall =
 110                         is_syscall(PT_REGS_IP(&current->thread.regs));
 111
 112         /*
 113          * if there's no signal to deliver, we just put the saved sigmask
 114          * back
 115          */
 116         if (!handled_sig)
 117                 restore_saved_sigmask();
 118         return handled_sig;
 119 }
 120
 121 int do_signal(void)
 122 {
 123         return kern_do_signal(&current->thread.regs);
 124 }