/*
   * Copyright (C) 2004-2006 Atmel Corporation
   *
   * Based on linux/arch/sh/kernel/signal.c
   *  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
   *  Copyright (C) 1991, 1992  Linus Torvalds
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <linux/sched.h>
  #include <linux/mm.h>
  #include <linux/errno.h>
  #include <linux/ptrace.h>
  #include <linux/unistd.h>

  #include <linux/freezer.h>

  #include <linux/tracehook.h>

  
  #include <asm/uaccess.h>
  #include <asm/ucontext.h>

  #include <asm/syscalls.h>

  
  #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  
  asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  			       struct pt_regs *regs)
  {
  	return do_sigaltstack(uss, uoss, regs->sp);
  }
  
  struct rt_sigframe
  {
  	struct siginfo info;
  	struct ucontext uc;
  	unsigned long retcode;
  };
  
  static int
  restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
  {
  	int err = 0;
  
  #define COPY(x)		err |= __get_user(regs->x, &sc->x)
  	COPY(sr);
  	COPY(pc);
  	COPY(lr);
  	COPY(sp);
  	COPY(r12);
  	COPY(r11);
  	COPY(r10);
  	COPY(r9);
  	COPY(r8);
  	COPY(r7);
  	COPY(r6);
  	COPY(r5);
  	COPY(r4);
  	COPY(r3);
  	COPY(r2);
  	COPY(r1);
  	COPY(r0);
  #undef	COPY
  
  	/*
  	 * Don't allow anyone to pretend they're running in supervisor
  	 * mode or something...
  	 */
  	err |= !valid_user_regs(regs);
  
  	return err;
  }
  
  
  asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
  {
  	struct rt_sigframe __user *frame;
  	sigset_t set;
  
  	frame = (struct rt_sigframe __user *)regs->sp;
  	pr_debug("SIG return: frame = %p
  ", frame);
  
  	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  		goto badframe;
  
  	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  		goto badframe;
  
  	sigdelsetmask(&set, ~_BLOCKABLE);
  	spin_lock_irq(&current->sighand->siglock);
  	current->blocked = set;
  	recalc_sigpending();
  	spin_unlock_irq(&current->sighand->siglock);
  
  	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  		goto badframe;

  	if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
  		goto badframe;

  	pr_debug("Context restored: pc = %08lx, lr = %08lx, sp = %08lx
  ",
  		 regs->pc, regs->lr, regs->sp);
  
  	return regs->r12;
  
  badframe:
  	force_sig(SIGSEGV, current);
  	return 0;
  }
  
  static int
  setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
  {
  	int err = 0;
  
  #define COPY(x)		err |= __put_user(regs->x, &sc->x)
  	COPY(sr);
  	COPY(pc);
  	COPY(lr);
  	COPY(sp);
  	COPY(r12);
  	COPY(r11);
  	COPY(r10);
  	COPY(r9);
  	COPY(r8);
  	COPY(r7);
  	COPY(r6);
  	COPY(r5);
  	COPY(r4);
  	COPY(r3);
  	COPY(r2);
  	COPY(r1);
  	COPY(r0);
  #undef	COPY
  
  	return err;
  }
  
  static inline void __user *
  get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
  {
  	unsigned long sp = regs->sp;
  
  	if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
  		sp = current->sas_ss_sp + current->sas_ss_size;
  
  	return (void __user *)((sp - framesize) & ~3);
  }
  
  static int
  setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
  	       sigset_t *set, struct pt_regs *regs)
  {
  	struct rt_sigframe __user *frame;
  	int err = 0;
  
  	frame = get_sigframe(ka, regs, sizeof(*frame));
  	err = -EFAULT;
  	if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
  		goto out;
  
  	/*
  	 * Set up the return code:
  	 *
  	 *	mov	r8, __NR_rt_sigreturn
  	 *	scall
  	 *
  	 * Note: This will blow up since we're using a non-executable
  	 * stack. Better use SA_RESTORER.
  	 */
  #if __NR_rt_sigreturn > 127
  # error __NR_rt_sigreturn must be < 127 to fit in a short mov
  #endif
  	err = __put_user(0x3008d733 | (__NR_rt_sigreturn << 20),
  			 &frame->retcode);
  
  	err |= copy_siginfo_to_user(&frame->info, info);
  
  	/* Set up the ucontext */
  	err |= __put_user(0, &frame->uc.uc_flags);
  	err |= __put_user(NULL, &frame->uc.uc_link);
  	err |= __put_user((void __user *)current->sas_ss_sp,
  			  &frame->uc.uc_stack.ss_sp);
  	err |= __put_user(sas_ss_flags(regs->sp),
  			  &frame->uc.uc_stack.ss_flags);
  	err |= __put_user(current->sas_ss_size,
  			  &frame->uc.uc_stack.ss_size);
  	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
  	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
  
  	if (err)
  		goto out;
  
  	regs->r12 = sig;
  	regs->r11 = (unsigned long) &frame->info;
  	regs->r10 = (unsigned long) &frame->uc;
  	regs->sp = (unsigned long) frame;
  	if (ka->sa.sa_flags & SA_RESTORER)
  		regs->lr = (unsigned long)ka->sa.sa_restorer;
  	else {
  		printk(KERN_NOTICE "[%s:%d] did not set SA_RESTORER
  ",
  		       current->comm, current->pid);
  		regs->lr = (unsigned long) &frame->retcode;
  	}
  
  	pr_debug("SIG deliver [%s:%d]: sig=%d sp=0x%lx pc=0x%lx->0x%p lr=0x%lx
  ",
  		 current->comm, current->pid, sig, regs->sp,
  		 regs->pc, ka->sa.sa_handler, regs->lr);
  
  	regs->pc = (unsigned long) ka->sa.sa_handler;
  
  out:
  	return err;
  }

  static inline void setup_syscall_restart(struct pt_regs *regs)

  {
  	if (regs->r12 == -ERESTART_RESTARTBLOCK)
  		regs->r8 = __NR_restart_syscall;
  	else
  		regs->r12 = regs->r12_orig;
  	regs->pc -= 2;
  }
  
  static inline void
  handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
  	      sigset_t *oldset, struct pt_regs *regs, int syscall)
  {
  	int ret;
  
  	/*
  	 * Set up the stack frame
  	 */
  	ret = setup_rt_frame(sig, ka, info, oldset, regs);
  
  	/*
  	 * Check that the resulting registers are sane
  	 */
  	ret |= !valid_user_regs(regs);
  
  	/*
  	 * Block the signal if we were unsuccessful.
  	 */
  	if (ret != 0 || !(ka->sa.sa_flags & SA_NODEFER)) {
  		spin_lock_irq(&current->sighand->siglock);
  		sigorsets(&current->blocked, &current->blocked,
  			  &ka->sa.sa_mask);
  		sigaddset(&current->blocked, sig);
  		recalc_sigpending();
  		spin_unlock_irq(&current->sighand->siglock);
  	}
  
  	if (ret == 0)
  		return;
  
  	force_sigsegv(sig, current);
  }
  
  /*
   * Note that 'init' is a special process: it doesn't get signals it
   * doesn't want to handle. Thus you cannot kill init even with a
   * SIGKILL even by mistake.
   */
  int do_signal(struct pt_regs *regs, sigset_t *oldset, int syscall)
  {
  	siginfo_t info;
  	int signr;
  	struct k_sigaction ka;
  
  	/*
  	 * We want the common case to go fast, which is why we may in
  	 * certain cases get here from kernel mode. Just return
  	 * without doing anything if so.
  	 */
  	if (!user_mode(regs))
  		return 0;

  	if (test_thread_flag(TIF_RESTORE_SIGMASK))
  		oldset = &current->saved_sigmask;
  	else if (!oldset)
  		oldset = &current->blocked;
  
  	signr = get_signal_to_deliver(&info, &ka, regs, NULL);

  	if (syscall) {
  		switch (regs->r12) {
  		case -ERESTART_RESTARTBLOCK:
  		case -ERESTARTNOHAND:
  			if (signr > 0) {
  				regs->r12 = -EINTR;
  				break;
  			}
  			/* fall through */
  		case -ERESTARTSYS:
  			if (signr > 0 && !(ka.sa.sa_flags & SA_RESTART)) {
  				regs->r12 = -EINTR;
  				break;
  			}
  			/* fall through */
  		case -ERESTARTNOINTR:

  			setup_syscall_restart(regs);

  		}
  	}
  
  	if (signr == 0) {
  		/* No signal to deliver -- put the saved sigmask back */
  		if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
  			clear_thread_flag(TIF_RESTORE_SIGMASK);
  			sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
  		}
  		return 0;
  	}
  
  	handle_signal(signr, &ka, &info, oldset, regs, syscall);
  	return 1;
  }
  
  asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
  {
  	int syscall = 0;
  
  	if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
  		syscall = 1;
  
  	if (ti->flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
  		do_signal(regs, &current->blocked, syscall);

  
  	if (ti->flags & _TIF_NOTIFY_RESUME) {
  		clear_thread_flag(TIF_NOTIFY_RESUME);
  		tracehook_notify_resume(regs);

  		if (current->replacement_session_keyring)
  			key_replace_session_keyring();

  	}

  }