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 /*
  19  * OK, we're invoking a handler
  20  */
  21 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
  22 {
  23         sigset_t *oldset = sigmask_to_save();
  24         int singlestep = 0;
  25         unsigned long sp;
  26         int err;
  27
  28         if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
  29                 singlestep = 1;
  30
  31         /* Did we come from a system call? */
  32         if (PT_REGS_SYSCALL_NR(regs) >= 0) {
  33                 /* If so, check system call restarting.. */
  34                 switch (PT_REGS_SYSCALL_RET(regs)) {
  35                 case -ERESTART_RESTARTBLOCK:
  36                 case -ERESTARTNOHAND:
  37                         PT_REGS_SYSCALL_RET(regs) = -EINTR;
  38                         break;
  39
  40                 case -ERESTARTSYS:
  41                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
  42                                 PT_REGS_SYSCALL_RET(regs) = -EINTR;
  43                                 break;
  44                         }
  45                 /* fallthrough */
  46                 case -ERESTARTNOINTR:
  47                         PT_REGS_RESTART_SYSCALL(regs);
  48                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  49                         break;
  50                 }
  51         }
  52
  53         sp = PT_REGS_SP(regs);
  54         if ((ksig->ka.sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
  55                 sp = current->sas_ss_sp + current->sas_ss_size;
  56
  57 #ifdef CONFIG_ARCH_HAS_SC_SIGNALS
  58         if (!(ksig->ka.sa.sa_flags & SA_SIGINFO))
  59                 err = setup_signal_stack_sc(sp, ksig, regs, oldset);
  60         else
  61 #endif
  62                 err = setup_signal_stack_si(sp, ksig, regs, oldset);
  63
  64         signal_setup_done(err, ksig, singlestep);
  65 }
  66
  67 void do_signal(struct pt_regs *regs)
  68 {
  69         struct ksignal ksig;
  70         int handled_sig = 0;
  71
  72         if (get_signal(&ksig)) {
  73                 handled_sig = 1;
  74                 /* Whee!  Actually deliver the signal.  */
  75                 handle_signal(&ksig, regs);
  76         }
  77
  78         /* Did we come from a system call? */
  79         if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {
  80                 /* Restart the system call - no handlers present */
  81                 switch (PT_REGS_SYSCALL_RET(regs)) {
  82                 case -ERESTARTNOHAND:
  83                 case -ERESTARTSYS:
  84                 case -ERESTARTNOINTR:
  85                         PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
  86                         PT_REGS_RESTART_SYSCALL(regs);
  87                         break;
  88                 case -ERESTART_RESTARTBLOCK:
  89                         PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
  90                         PT_REGS_RESTART_SYSCALL(regs);
  91                         break;
  92                 }
  93         }
  94
  95         /*
  96          * This closes a way to execute a system call on the host.  If
  97          * you set a breakpoint on a system call instruction and singlestep
  98          * from it, the tracing thread used to PTRACE_SINGLESTEP the process
  99          * rather than PTRACE_SYSCALL it, allowing the system call to execute
 100          * on the host.  The tracing thread will check this flag and
 101          * PTRACE_SYSCALL if necessary.
 102          */
 103         if (current->ptrace & PT_DTRACE)
 104                 current->thread.singlestep_syscall =
 105                         is_syscall(PT_REGS_IP(&current->thread.regs));
 106
 107         /*
 108          * if there's no signal to deliver, we just put the saved sigmask
 109          * back
 110          */
 111         if (!handled_sig)
 112                 restore_saved_sigmask();
 113 }