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 "user_util.h"
  21 #include "asm/ucontext.h"
  22 #include "kern_util.h"
  23 #include "signal_kern.h"
  24 #include "kern.h"
  25 #include "frame_kern.h"
  26 #include "sigcontext.h"
  27 #include "mode.h"
  28
  29 EXPORT_SYMBOL(block_signals);
  30 EXPORT_SYMBOL(unblock_signals);
  31
  32 #define _S(nr) (1<<((nr)-1))
  33
  34 #define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
  35
  36 /*
  37  * OK, we're invoking a handler
  38  */
  39 static int handle_signal(struct pt_regs *regs, unsigned long signr,
  40                          struct k_sigaction *ka, siginfo_t *info,
  41                          sigset_t *oldset)
  42 {
  43         unsigned long sp;
  44         int err;
  45
  46         /* Always make any pending restarted system calls return -EINTR */
  47         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  48
  49         /* Did we come from a system call? */
  50         if(PT_REGS_SYSCALL_NR(regs) >= 0){
  51                 /* If so, check system call restarting.. */
  52                 switch(PT_REGS_SYSCALL_RET(regs)){
  53                 case -ERESTART_RESTARTBLOCK:
  54                 case -ERESTARTNOHAND:
  55                         PT_REGS_SYSCALL_RET(regs) = -EINTR;
  56                         break;
  57
  58                 case -ERESTARTSYS:
  59                         if (!(ka->sa.sa_flags & SA_RESTART)) {
  60                                 PT_REGS_SYSCALL_RET(regs) = -EINTR;
  61                                 break;
  62                         }
  63                 /* fallthrough */
  64                 case -ERESTARTNOINTR:
  65                         PT_REGS_RESTART_SYSCALL(regs);
  66                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  67                         break;
  68                 }
  69         }
  70
  71         sp = PT_REGS_SP(regs);
  72         if((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
  73                 sp = current->sas_ss_sp + current->sas_ss_size;
  74
  75 #ifdef CONFIG_ARCH_HAS_SC_SIGNALS
  76         if(!(ka->sa.sa_flags & SA_SIGINFO))
  77                 err = setup_signal_stack_sc(sp, signr, ka, regs, oldset);
  78         else
  79 #endif
  80                 err = setup_signal_stack_si(sp, signr, ka, regs, info, oldset);
  81
  82         if(err){
  83                 spin_lock_irq(&current->sighand->siglock);
  84                 current->blocked = *oldset;
  85                 recalc_sigpending();
  86                 spin_unlock_irq(&current->sighand->siglock);
  87                 force_sigsegv(signr, current);
  88         } else {
  89                 spin_lock_irq(&current->sighand->siglock);
  90                 sigorsets(&current->blocked, &current->blocked,
  91                           &ka->sa.sa_mask);
  92                  if(!(ka->sa.sa_flags & SA_NODEFER))
  93                         sigaddset(&current->blocked, signr);
  94                 recalc_sigpending();
  95                 spin_unlock_irq(&current->sighand->siglock);
  96         }
  97
  98         return err;
  99 }
 100
 101 static int kern_do_signal(struct pt_regs *regs)
 102 {
 103         struct k_sigaction ka_copy;
 104         siginfo_t info;
 105         sigset_t *oldset;
 106         int sig, handled_sig = 0;
 107
 108         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 109                 oldset = &current->saved_sigmask;
 110         else
 111                 oldset = &current->blocked;
 112
 113         while((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0){
 114                 handled_sig = 1;
 115                 /* Whee!  Actually deliver the signal.  */
 116                 if(!handle_signal(regs, sig, &ka_copy, &info, oldset)){
 117                         /* a signal was successfully delivered; the saved
 118                          * sigmask will have been stored in the signal frame,
 119                          * and will be restored by sigreturn, so we can simply
 120                          * clear the TIF_RESTORE_SIGMASK flag */
 121                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 122                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 123                         break;
 124                 }
 125         }
 126
 127         /* Did we come from a system call? */
 128         if(!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)){
 129                 /* Restart the system call - no handlers present */
 130                 switch(PT_REGS_SYSCALL_RET(regs)){
 131                 case -ERESTARTNOHAND:
 132                 case -ERESTARTSYS:
 133                 case -ERESTARTNOINTR:
 134                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
 135                         PT_REGS_RESTART_SYSCALL(regs);
 136                         break;
 137                 case -ERESTART_RESTARTBLOCK:
 138                         PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
 139                         PT_REGS_RESTART_SYSCALL(regs);
 140                         break;
 141                 }
 142         }
 143
 144         /* This closes a way to execute a system call on the host.  If
 145          * you set a breakpoint on a system call instruction and singlestep
 146          * from it, the tracing thread used to PTRACE_SINGLESTEP the process
 147          * rather than PTRACE_SYSCALL it, allowing the system call to execute
 148          * on the host.  The tracing thread will check this flag and
 149          * PTRACE_SYSCALL if necessary.
 150          */
 151         if(current->ptrace & PT_DTRACE)
 152                 current->thread.singlestep_syscall =
 153                         is_syscall(PT_REGS_IP(&current->thread.regs));
 154
 155         /* if there's no signal to deliver, we just put the saved sigmask
 156          * back */
 157         if (!handled_sig && test_thread_flag(TIF_RESTORE_SIGMASK)) {
 158                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 159                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 160         }
 161         return(handled_sig);
 162 }
 163
 164 int do_signal(void)
 165 {
 166         return(kern_do_signal(&current->thread.regs));
 167 }
 168
 169 /*
 170  * Atomically swap in the new signal mask, and wait for a signal.
 171  */
 172 long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 173 {
 174         mask &= _BLOCKABLE;
 175         spin_lock_irq(&current->sighand->siglock);
 176         current->saved_sigmask = current->blocked;
 177         siginitset(&current->blocked, mask);
 178         recalc_sigpending();
 179         spin_unlock_irq(&current->sighand->siglock);
 180
 181         current->state = TASK_INTERRUPTIBLE;
 182         schedule();
 183         set_thread_flag(TIF_RESTORE_SIGMASK);
 184         return -ERESTARTNOHAND;
 185 }
 186
 187 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 188 {
 189         return(do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs)));
 190 }