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