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         int sig, handled_sig = 0;
  78
  79         while ((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0) {
  80                 sigset_t *oldset;
  81                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
  82                         oldset = &current->saved_sigmask;
  83                 else
  84                         oldset = &current->blocked;
  85                 handled_sig = 1;
  86                 /* Whee!  Actually deliver the signal.  */
  87                 if (!handle_signal(regs, sig, &ka_copy, &info, oldset)) {
  88                         /*
  89                          * a signal was successfully delivered; the saved
  90                          * sigmask will have been stored in the signal frame,
  91                          * and will be restored by sigreturn, so we can simply
  92                          * clear the TIF_RESTORE_SIGMASK flag
  93                          */
  94                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
  95                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
  96                         break;
  97                 }
  98         }
  99
 100         /* Did we come from a system call? */
 101         if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {
 102                 /* Restart the system call - no handlers present */
 103                 switch (PT_REGS_SYSCALL_RET(regs)) {
 104                 case -ERESTARTNOHAND:
 105                 case -ERESTARTSYS:
 106                 case -ERESTARTNOINTR:
 107                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
 108                         PT_REGS_RESTART_SYSCALL(regs);
 109                         break;
 110                 case -ERESTART_RESTARTBLOCK:
 111                         PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
 112                         PT_REGS_RESTART_SYSCALL(regs);
 113                         break;
 114                 }
 115         }
 116
 117         /*
 118          * This closes a way to execute a system call on the host.  If
 119          * you set a breakpoint on a system call instruction and singlestep
 120          * from it, the tracing thread used to PTRACE_SINGLESTEP the process
 121          * rather than PTRACE_SYSCALL it, allowing the system call to execute
 122          * on the host.  The tracing thread will check this flag and
 123          * PTRACE_SYSCALL if necessary.
 124          */
 125         if (current->ptrace & PT_DTRACE)
 126                 current->thread.singlestep_syscall =
 127                         is_syscall(PT_REGS_IP(&current->thread.regs));
 128
 129         /*
 130          * if there's no signal to deliver, we just put the saved sigmask
 131          * back
 132          */
 133         if (!handled_sig)
 134                 restore_saved_sigmask();
 135         return handled_sig;
 136 }
 137
 138 int do_signal(void)
 139 {
 140         return kern_do_signal(&current->thread.regs);
 141 }
 142
 143 /*
 144  * Atomically swap in the new signal mask, and wait for a signal.
 145  */
 146 long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 147 {
 148         sigset_t blocked;
 149         siginitset(&blocked, mask);
 150         return sigsuspend(&blocked);
 151 }
 152
 153 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 154 {
 155         return do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs));
 156 }