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/config.h"
   7 #include "linux/stddef.h"
   8 #include "linux/sys.h"
   9 #include "linux/sched.h"
  10 #include "linux/wait.h"
  11 #include "linux/kernel.h"
  12 #include "linux/smp_lock.h"
  13 #include "linux/module.h"
  14 #include "linux/slab.h"
  15 #include "linux/tty.h"
  16 #include "linux/binfmts.h"
  17 #include "linux/ptrace.h"
  18 #include "asm/signal.h"
  19 #include "asm/uaccess.h"
  20 #include "asm/unistd.h"
  21 #include "user_util.h"
  22 #include "asm/ucontext.h"
  23 #include "kern_util.h"
  24 #include "signal_kern.h"
  25 #include "kern.h"
  26 #include "frame_kern.h"
  27 #include "sigcontext.h"
  28 #include "mode.h"
  29
  30 EXPORT_SYMBOL(block_signals);
  31 EXPORT_SYMBOL(unblock_signals);
  32
  33 #define _S(nr) (1<<((nr)-1))
  34
  35 #define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
  36
  37 /*
  38  * OK, we're invoking a handler
  39  */
  40 static int handle_signal(struct pt_regs *regs, unsigned long signr,
  41                          struct k_sigaction *ka, siginfo_t *info,
  42                          sigset_t *oldset)
  43 {
  44         unsigned long sp;
  45         int err;
  46
  47         /* Always make any pending restarted system calls return -EINTR */
  48         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  49
  50         /* Did we come from a system call? */
  51         if(PT_REGS_SYSCALL_NR(regs) >= 0){
  52                 /* If so, check system call restarting.. */
  53                 switch(PT_REGS_SYSCALL_RET(regs)){
  54                 case -ERESTART_RESTARTBLOCK:
  55                 case -ERESTARTNOHAND:
  56                         PT_REGS_SYSCALL_RET(regs) = -EINTR;
  57                         break;
  58
  59                 case -ERESTARTSYS:
  60                         if (!(ka->sa.sa_flags & SA_RESTART)) {
  61                                 PT_REGS_SYSCALL_RET(regs) = -EINTR;
  62                                 break;
  63                         }
  64                 /* fallthrough */
  65                 case -ERESTARTNOINTR:
  66                         PT_REGS_RESTART_SYSCALL(regs);
  67                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  68                         break;
  69                 }
  70         }
  71
  72         sp = PT_REGS_SP(regs);
  73         if((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
  74                 sp = current->sas_ss_sp + current->sas_ss_size;
  75
  76 #ifdef CONFIG_ARCH_HAS_SC_SIGNALS
  77         if(!(ka->sa.sa_flags & SA_SIGINFO))
  78                 err = setup_signal_stack_sc(sp, signr, ka, regs, oldset);
  79         else
  80 #endif
  81                 err = setup_signal_stack_si(sp, signr, ka, regs, info, oldset);
  82
  83         if(err){
  84                 spin_lock_irq(&current->sighand->siglock);
  85                 current->blocked = *oldset;
  86                 recalc_sigpending();
  87                 spin_unlock_irq(&current->sighand->siglock);
  88                 force_sigsegv(signr, current);
  89         } else {
  90                 spin_lock_irq(&current->sighand->siglock);
  91                 sigorsets(&current->blocked, &current->blocked,
  92                           &ka->sa.sa_mask);
  93                  if(!(ka->sa.sa_flags & SA_NODEFER))
  94                         sigaddset(&current->blocked, signr);
  95                 recalc_sigpending();
  96                 spin_unlock_irq(&current->sighand->siglock);
  97         }
  98
  99         return err;
 100 }
 101
 102 static int kern_do_signal(struct pt_regs *regs)
 103 {
 104         struct k_sigaction ka_copy;
 105         siginfo_t info;
 106         sigset_t *oldset;
 107         int sig, handled_sig = 0;
 108
 109         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 110                 oldset = &current->saved_sigmask;
 111         else
 112                 oldset = &current->blocked;
 113
 114         while((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0){
 115                 handled_sig = 1;
 116                 /* Whee!  Actually deliver the signal.  */
 117                 if(!handle_signal(regs, sig, &ka_copy, &info, oldset)){
 118                         /* a signal was successfully delivered; the saved
 119                          * sigmask will have been stored in the signal frame,
 120                          * and will be restored by sigreturn, so we can simply
 121                          * clear the TIF_RESTORE_SIGMASK flag */
 122                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 123                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 124                         break;
 125                 }
 126         }
 127
 128         /* Did we come from a system call? */
 129         if(!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)){
 130                 /* Restart the system call - no handlers present */
 131                 switch(PT_REGS_SYSCALL_RET(regs)){
 132                 case -ERESTARTNOHAND:
 133                 case -ERESTARTSYS:
 134                 case -ERESTARTNOINTR:
 135                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
 136                         PT_REGS_RESTART_SYSCALL(regs);
 137                         break;
 138                 case -ERESTART_RESTARTBLOCK:
 139                         PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
 140                         PT_REGS_RESTART_SYSCALL(regs);
 141                         break;
 142                 }
 143         }
 144
 145         /* This closes a way to execute a system call on the host.  If
 146          * you set a breakpoint on a system call instruction and singlestep
 147          * from it, the tracing thread used to PTRACE_SINGLESTEP the process
 148          * rather than PTRACE_SYSCALL it, allowing the system call to execute
 149          * on the host.  The tracing thread will check this flag and
 150          * PTRACE_SYSCALL if necessary.
 151          */
 152         if(current->ptrace & PT_DTRACE)
 153                 current->thread.singlestep_syscall =
 154                         is_syscall(PT_REGS_IP(&current->thread.regs));
 155
 156         /* if there's no signal to deliver, we just put the saved sigmask
 157          * back */
 158         if (!handled_sig && test_thread_flag(TIF_RESTORE_SIGMASK)) {
 159                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 160                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 161         }
 162         return(handled_sig);
 163 }
 164
 165 int do_signal(void)
 166 {
 167         return(kern_do_signal(&current->thread.regs));
 168 }
 169
 170 /*
 171  * Atomically swap in the new signal mask, and wait for a signal.
 172  */
 173 long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 174 {
 175         mask &= _BLOCKABLE;
 176         spin_lock_irq(&current->sighand->siglock);
 177         current->saved_sigmask = current->blocked;
 178         siginitset(&current->blocked, mask);
 179         recalc_sigpending();
 180         spin_unlock_irq(&current->sighand->siglock);
 181
 182         current->state = TASK_INTERRUPTIBLE;
 183         schedule();
 184         set_thread_flag(TIF_RESTORE_SIGMASK);
 185         return -ERESTARTNOHAND;
 186 }
 187
 188 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 189 {
 190         return(do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs)));
 191 }