arch/um/kernel/signal.c

   1 /*
   2  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/stddef.h"
   7 #include "linux/sys.h"
   8 #include "linux/sched.h"
   9 #include "linux/wait.h"
  10 #include "linux/kernel.h"
  11 #include "linux/smp_lock.h"
  12 #include "linux/module.h"
  13 #include "linux/slab.h"
  14 #include "linux/tty.h"
  15 #include "linux/binfmts.h"
  16 #include "linux/ptrace.h"
  17 #include "asm/signal.h"
  18 #include "asm/uaccess.h"
  19 #include "asm/unistd.h"
  20 #include "asm/ucontext.h"
  21 #include "kern_util.h"
  22 #include "signal_kern.h"
  23 #include "kern.h"
  24 #include "frame_kern.h"
  25 #include "sigcontext.h"
  26 #include "mode.h"
  27
  28 EXPORT_SYMBOL(block_signals);
  29 EXPORT_SYMBOL(unblock_signals);
  30
  31 #define _S(nr) (1<<((nr)-1))
  32
  33 #define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
  34
  35 /*
  36  * OK, we're invoking a handler
  37  */
  38 static int handle_signal(struct pt_regs *regs, unsigned long signr,
  39                          struct k_sigaction *ka, siginfo_t *info,
  40                          sigset_t *oldset)
  41 {
  42         unsigned long sp;
  43         int err;
  44
  45         /* Always make any pending restarted system calls return -EINTR */
  46         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  47
  48         /* Did we come from a system call? */
  49         if(PT_REGS_SYSCALL_NR(regs) >= 0){
  50                 /* If so, check system call restarting.. */
  51                 switch(PT_REGS_SYSCALL_RET(regs)){
  52                 case -ERESTART_RESTARTBLOCK:
  53                 case -ERESTARTNOHAND:
  54                         PT_REGS_SYSCALL_RET(regs) = -EINTR;
  55                         break;
  56
  57                 case -ERESTARTSYS:
  58                         if (!(ka->sa.sa_flags & SA_RESTART)) {
  59                                 PT_REGS_SYSCALL_RET(regs) = -EINTR;
  60                                 break;
  61                         }
  62                 /* fallthrough */
  63                 case -ERESTARTNOINTR:
  64                         PT_REGS_RESTART_SYSCALL(regs);
  65                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  66                         break;
  67                 }
  68         }
  69
  70         sp = PT_REGS_SP(regs);
  71         if((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
  72                 sp = current->sas_ss_sp + current->sas_ss_size;
  73
  74 #ifdef CONFIG_ARCH_HAS_SC_SIGNALS
  75         if(!(ka->sa.sa_flags & SA_SIGINFO))
  76                 err = setup_signal_stack_sc(sp, signr, ka, regs, oldset);
  77         else
  78 #endif
  79                 err = setup_signal_stack_si(sp, signr, ka, regs, info, oldset);
  80
  81         if(err){
  82                 spin_lock_irq(&current->sighand->siglock);
  83                 current->blocked = *oldset;
  84                 recalc_sigpending();
  85                 spin_unlock_irq(&current->sighand->siglock);
  86                 force_sigsegv(signr, current);
  87         } else {
  88                 spin_lock_irq(&current->sighand->siglock);
  89                 sigorsets(&current->blocked, &current->blocked,
  90                           &ka->sa.sa_mask);
  91                  if(!(ka->sa.sa_flags & SA_NODEFER))
  92                         sigaddset(&current->blocked, signr);
  93                 recalc_sigpending();
  94                 spin_unlock_irq(&current->sighand->siglock);
  95         }
  96
  97         return err;
  98 }
  99
 100 static int kern_do_signal(struct pt_regs *regs)
 101 {
 102         struct k_sigaction ka_copy;
 103         siginfo_t info;
 104         sigset_t *oldset;
 105         int sig, handled_sig = 0;
 106
 107         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 108                 oldset = &current->saved_sigmask;
 109         else
 110                 oldset = &current->blocked;
 111
 112         while((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0){
 113                 handled_sig = 1;
 114                 /* Whee!  Actually deliver the signal.  */
 115                 if(!handle_signal(regs, sig, &ka_copy, &info, oldset)){
 116                         /* a signal was successfully delivered; the saved
 117                          * sigmask will have been stored in the signal frame,
 118                          * and will be restored by sigreturn, so we can simply
 119                          * clear the TIF_RESTORE_SIGMASK flag */
 120                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 121                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 122                         break;
 123                 }
 124         }
 125
 126         /* Did we come from a system call? */
 127         if(!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)){
 128                 /* Restart the system call - no handlers present */
 129                 switch(PT_REGS_SYSCALL_RET(regs)){
 130                 case -ERESTARTNOHAND:
 131                 case -ERESTARTSYS:
 132                 case -ERESTARTNOINTR:
 133                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
 134                         PT_REGS_RESTART_SYSCALL(regs);
 135                         break;
 136                 case -ERESTART_RESTARTBLOCK:
 137                         PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
 138                         PT_REGS_RESTART_SYSCALL(regs);
 139                         break;
 140                 }
 141         }
 142
 143         /* This closes a way to execute a system call on the host.  If
 144          * you set a breakpoint on a system call instruction and singlestep
 145          * from it, the tracing thread used to PTRACE_SINGLESTEP the process
 146          * rather than PTRACE_SYSCALL it, allowing the system call to execute
 147          * on the host.  The tracing thread will check this flag and
 148          * PTRACE_SYSCALL if necessary.
 149          */
 150         if(current->ptrace & PT_DTRACE)
 151                 current->thread.singlestep_syscall =
 152                         is_syscall(PT_REGS_IP(&current->thread.regs));
 153
 154         /* if there's no signal to deliver, we just put the saved sigmask
 155          * back */
 156         if (!handled_sig && test_thread_flag(TIF_RESTORE_SIGMASK)) {
 157                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 158                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 159         }
 160         return handled_sig;
 161 }
 162
 163 int do_signal(void)
 164 {
 165         return kern_do_signal(&current->thread.regs);
 166 }
 167
 168 /*
 169  * Atomically swap in the new signal mask, and wait for a signal.
 170  */
 171 long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 172 {
 173         mask &= _BLOCKABLE;
 174         spin_lock_irq(&current->sighand->siglock);
 175         current->saved_sigmask = current->blocked;
 176         siginitset(&current->blocked, mask);
 177         recalc_sigpending();
 178         spin_unlock_irq(&current->sighand->siglock);
 179
 180         current->state = TASK_INTERRUPTIBLE;
 181         schedule();
 182         set_thread_flag(TIF_RESTORE_SIGMASK);
 183         return -ERESTARTNOHAND;
 184 }
 185
 186 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 187 {
 188         return do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs));
 189 }