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 #include <sysdep/sigcontext.h>
  15
  16 EXPORT_SYMBOL(block_signals);
  17 EXPORT_SYMBOL(unblock_signals);
  18
  19 #define _S(nr) (1<<((nr)-1))
  20
  21 #define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
  22
  23 /*
  24  * OK, we're invoking a handler
  25  */
  26 static int handle_signal(struct pt_regs *regs, unsigned long signr,
  27                          struct k_sigaction *ka, siginfo_t *info,
  28                          sigset_t *oldset)
  29 {
  30         unsigned long sp;
  31         int err;
  32
  33         /* Always make any pending restarted system calls return -EINTR */
  34         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  35
  36         /* Did we come from a system call? */
  37         if (PT_REGS_SYSCALL_NR(regs) >= 0) {
  38                 /* If so, check system call restarting.. */
  39                 switch (PT_REGS_SYSCALL_RET(regs)) {
  40                 case -ERESTART_RESTARTBLOCK:
  41                 case -ERESTARTNOHAND:
  42                         PT_REGS_SYSCALL_RET(regs) = -EINTR;
  43                         break;
  44
  45                 case -ERESTARTSYS:
  46                         if (!(ka->sa.sa_flags & SA_RESTART)) {
  47                                 PT_REGS_SYSCALL_RET(regs) = -EINTR;
  48                                 break;
  49                         }
  50                 /* fallthrough */
  51                 case -ERESTARTNOINTR:
  52                         PT_REGS_RESTART_SYSCALL(regs);
  53                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  54                         break;
  55                 }
  56         }
  57
  58         sp = PT_REGS_SP(regs);
  59         if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
  60                 sp = current->sas_ss_sp + current->sas_ss_size;
  61
  62 #ifdef CONFIG_ARCH_HAS_SC_SIGNALS
  63         if (!(ka->sa.sa_flags & SA_SIGINFO))
  64                 err = setup_signal_stack_sc(sp, signr, ka, regs, oldset);
  65         else
  66 #endif
  67                 err = setup_signal_stack_si(sp, signr, ka, regs, info, oldset);
  68
  69         if (err)
  70                 force_sigsegv(signr, current);
  71         else
  72                 block_sigmask(ka, signr);
  73
  74         return err;
  75 }
  76
  77 static int kern_do_signal(struct pt_regs *regs)
  78 {
  79         struct k_sigaction ka_copy;
  80         siginfo_t info;
  81         sigset_t *oldset;
  82         int sig, handled_sig = 0;
  83
  84         if (test_thread_flag(TIF_RESTORE_SIGMASK))
  85                 oldset = &current->saved_sigmask;
  86         else
  87                 oldset = &current->blocked;
  88
  89         while ((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0) {
  90                 handled_sig = 1;
  91                 /* Whee!  Actually deliver the signal.  */
  92                 if (!handle_signal(regs, sig, &ka_copy, &info, oldset)) {
  93                         /*
  94                          * a signal was successfully delivered; the saved
  95                          * sigmask will have been stored in the signal frame,
  96                          * and will be restored by sigreturn, so we can simply
  97                          * clear the TIF_RESTORE_SIGMASK flag
  98                          */
  99                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 100                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 101                         break;
 102                 }
 103         }
 104
 105         /* Did we come from a system call? */
 106         if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {
 107                 /* Restart the system call - no handlers present */
 108                 switch (PT_REGS_SYSCALL_RET(regs)) {
 109                 case -ERESTARTNOHAND:
 110                 case -ERESTARTSYS:
 111                 case -ERESTARTNOINTR:
 112                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
 113                         PT_REGS_RESTART_SYSCALL(regs);
 114                         break;
 115                 case -ERESTART_RESTARTBLOCK:
 116                         PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
 117                         PT_REGS_RESTART_SYSCALL(regs);
 118                         break;
 119                 }
 120         }
 121
 122         /*
 123          * This closes a way to execute a system call on the host.  If
 124          * you set a breakpoint on a system call instruction and singlestep
 125          * from it, the tracing thread used to PTRACE_SINGLESTEP the process
 126          * rather than PTRACE_SYSCALL it, allowing the system call to execute
 127          * on the host.  The tracing thread will check this flag and
 128          * PTRACE_SYSCALL if necessary.
 129          */
 130         if (current->ptrace & PT_DTRACE)
 131                 current->thread.singlestep_syscall =
 132                         is_syscall(PT_REGS_IP(&current->thread.regs));
 133
 134         /*
 135          * if there's no signal to deliver, we just put the saved sigmask
 136          * back
 137          */
 138         if (!handled_sig && test_thread_flag(TIF_RESTORE_SIGMASK)) {
 139                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 140                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 141         }
 142         return handled_sig;
 143 }
 144
 145 int do_signal(void)
 146 {
 147         return kern_do_signal(&current->thread.regs);
 148 }
 149
 150 /*
 151  * Atomically swap in the new signal mask, and wait for a signal.
 152  */
 153 long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 154 {
 155         sigset_t blocked;
 156
 157         current->saved_sigmask = current->blocked;
 158
 159         mask &= _BLOCKABLE;
 160         siginitset(&blocked, mask);
 161         set_current_blocked(&blocked);
 162
 163         current->state = TASK_INTERRUPTIBLE;
 164         schedule();
 165         set_thread_flag(TIF_RESTORE_SIGMASK);
 166         return -ERESTARTNOHAND;
 167 }
 168
 169 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 170 {
 171         return do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs));
 172 }