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