LXR linux/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
  15EXPORT_SYMBOL(block_signals);
  16EXPORT_SYMBOL(unblock_signals);
  17
  18/*
  19 * OK, we're invoking a handler
  20 */
  21static 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
  67void do_signal(struct pt_regs *regs)
  68{
  69        struct ksignal ksig;
  70        int handled_sig = 0;
  71
  72        while (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}
 114