/*

   *  Copyright (C) 1991, 1992  Linus Torvalds

   *  Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs

   *
   *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes

   *  2000-2002   x86-64 support by Andi Kleen

   */

  #include <linux/sched.h>
  #include <linux/mm.h>
  #include <linux/smp.h>

  #include <linux/kernel.h>
  #include <linux/signal.h>
  #include <linux/errno.h>
  #include <linux/wait.h>

  #include <linux/ptrace.h>

  #include <linux/tracehook.h>

  #include <linux/unistd.h>
  #include <linux/stddef.h>
  #include <linux/personality.h>
  #include <linux/uaccess.h>

  #include <linux/user-return-notifier.h>

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

  #include <asm/i387.h>

  #include <asm/vdso.h>

  #include <asm/mce.h>

  
  #ifdef CONFIG_X86_64
  #include <asm/proto.h>
  #include <asm/ia32_unistd.h>

  #endif /* CONFIG_X86_64 */

  #include <asm/syscall.h>

  #include <asm/syscalls.h>

  #include <asm/sigframe.h>

  #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

  #define __FIX_EFLAGS	(X86_EFLAGS_AC | X86_EFLAGS_OF | \
  			 X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
  			 X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
  			 X86_EFLAGS_CF)
  
  #ifdef CONFIG_X86_32
  # define FIX_EFLAGS	(__FIX_EFLAGS | X86_EFLAGS_RF)
  #else
  # define FIX_EFLAGS	__FIX_EFLAGS
  #endif

  #define COPY(x)			do {			\
  	get_user_ex(regs->x, &sc->x);			\
  } while (0)

  #define GET_SEG(seg)		({			\
  	unsigned short tmp;				\
  	get_user_ex(tmp, &sc->seg);			\
  	tmp;						\
  })

  #define COPY_SEG(seg)		do {			\
  	regs->seg = GET_SEG(seg);			\
  } while (0)

  #define COPY_SEG_CPL3(seg)	do {			\
  	regs->seg = GET_SEG(seg) | 3;			\
  } while (0)

  
  static int
  restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
  		   unsigned long *pax)
  {
  	void __user *buf;
  	unsigned int tmpflags;
  	unsigned int err = 0;
  
  	/* Always make any pending restarted system calls return -EINTR */
  	current_thread_info()->restart_block.fn = do_no_restart_syscall;

  	get_user_try {

  #ifdef CONFIG_X86_32

  		set_user_gs(regs, GET_SEG(gs));

  		COPY_SEG(fs);
  		COPY_SEG(es);
  		COPY_SEG(ds);

  #endif /* CONFIG_X86_32 */

  		COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
  		COPY(dx); COPY(cx); COPY(ip);

  
  #ifdef CONFIG_X86_64

  		COPY(r8);
  		COPY(r9);
  		COPY(r10);
  		COPY(r11);
  		COPY(r12);
  		COPY(r13);
  		COPY(r14);
  		COPY(r15);

  #endif /* CONFIG_X86_64 */
  
  #ifdef CONFIG_X86_32

  		COPY_SEG_CPL3(cs);
  		COPY_SEG_CPL3(ss);

  #else /* !CONFIG_X86_32 */

  		/* Kernel saves and restores only the CS segment register on signals,
  		 * which is the bare minimum needed to allow mixed 32/64-bit code.
  		 * App's signal handler can save/restore other segments if needed. */
  		COPY_SEG_CPL3(cs);

  #endif /* CONFIG_X86_32 */

  		get_user_ex(tmpflags, &sc->flags);
  		regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
  		regs->orig_ax = -1;		/* disable syscall checks */
  
  		get_user_ex(buf, &sc->fpstate);
  		err |= restore_i387_xstate(buf);

  		get_user_ex(*pax, &sc->ax);
  	} get_user_catch(err);

  	return err;
  }
  
  static int
  setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
  		 struct pt_regs *regs, unsigned long mask)
  {
  	int err = 0;

  	put_user_try {

  #ifdef CONFIG_X86_32

  		put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);

  		put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
  		put_user_ex(regs->es, (unsigned int __user *)&sc->es);
  		put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);

  #endif /* CONFIG_X86_32 */

  		put_user_ex(regs->di, &sc->di);
  		put_user_ex(regs->si, &sc->si);
  		put_user_ex(regs->bp, &sc->bp);
  		put_user_ex(regs->sp, &sc->sp);
  		put_user_ex(regs->bx, &sc->bx);
  		put_user_ex(regs->dx, &sc->dx);
  		put_user_ex(regs->cx, &sc->cx);
  		put_user_ex(regs->ax, &sc->ax);

  #ifdef CONFIG_X86_64

  		put_user_ex(regs->r8, &sc->r8);
  		put_user_ex(regs->r9, &sc->r9);
  		put_user_ex(regs->r10, &sc->r10);
  		put_user_ex(regs->r11, &sc->r11);
  		put_user_ex(regs->r12, &sc->r12);
  		put_user_ex(regs->r13, &sc->r13);
  		put_user_ex(regs->r14, &sc->r14);
  		put_user_ex(regs->r15, &sc->r15);

  #endif /* CONFIG_X86_64 */

  		put_user_ex(current->thread.trap_no, &sc->trapno);
  		put_user_ex(current->thread.error_code, &sc->err);
  		put_user_ex(regs->ip, &sc->ip);

  #ifdef CONFIG_X86_32

  		put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
  		put_user_ex(regs->flags, &sc->flags);
  		put_user_ex(regs->sp, &sc->sp_at_signal);
  		put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);

  #else /* !CONFIG_X86_32 */

  		put_user_ex(regs->flags, &sc->flags);
  		put_user_ex(regs->cs, &sc->cs);
  		put_user_ex(0, &sc->gs);
  		put_user_ex(0, &sc->fs);

  #endif /* CONFIG_X86_32 */

  		put_user_ex(fpstate, &sc->fpstate);

  		/* non-iBCS2 extensions.. */
  		put_user_ex(mask, &sc->oldmask);
  		put_user_ex(current->thread.cr2, &sc->cr2);
  	} put_user_catch(err);

  
  	return err;
  }

  /*

   * Set up a signal frame.

   */

  
  /*
   * Determine which stack to use..
   */

  static unsigned long align_sigframe(unsigned long sp)
  {
  #ifdef CONFIG_X86_32
  	/*
  	 * Align the stack pointer according to the i386 ABI,
  	 * i.e. so that on function entry ((sp + 4) & 15) == 0.
  	 */
  	sp = ((sp + 4) & -16ul) - 4;
  #else /* !CONFIG_X86_32 */
  	sp = round_down(sp, 16) - 8;
  #endif
  	return sp;
  }

  static inline void __user *

  get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,

  	     void __user **fpstate)

  {

  	/* Default to using normal stack */

  	unsigned long sp = regs->sp;

  	int onsigstack = on_sig_stack(sp);

  
  #ifdef CONFIG_X86_64
  	/* redzone */
  	sp -= 128;
  #endif /* CONFIG_X86_64 */

  	if (!onsigstack) {
  		/* This is the X/Open sanctioned signal stack switching.  */
  		if (ka->sa.sa_flags & SA_ONSTACK) {

  			if (current->sas_ss_size)

  				sp = current->sas_ss_sp + current->sas_ss_size;
  		} else {

  #ifdef CONFIG_X86_32

  			/* This is the legacy signal stack switching. */
  			if ((regs->ss & 0xffff) != __USER_DS &&
  				!(ka->sa.sa_flags & SA_RESTORER) &&
  					ka->sa.sa_restorer)
  				sp = (unsigned long) ka->sa.sa_restorer;

  #endif /* CONFIG_X86_32 */

  		}

  	}

  	if (used_math()) {

  		sp -= sig_xstate_size;

  #ifdef CONFIG_X86_64
  		sp = round_down(sp, 64);
  #endif /* CONFIG_X86_64 */
  		*fpstate = (void __user *)sp;

  	}

  	sp = align_sigframe(sp - frame_size);
  
  	/*
  	 * If we are on the alternate signal stack and would overflow it, don't.
  	 * Return an always-bogus address instead so we will die with SIGSEGV.
  	 */
  	if (onsigstack && !likely(on_sig_stack(sp)))
  		return (void __user *)-1L;
  
  	/* save i387 state */
  	if (used_math() && save_i387_xstate(*fpstate) < 0)
  		return (void __user *)-1L;
  
  	return (void __user *)sp;

  }

  #ifdef CONFIG_X86_32
  static const struct {
  	u16 poplmovl;
  	u32 val;
  	u16 int80;
  } __attribute__((packed)) retcode = {
  	0xb858,		/* popl %eax; movl $..., %eax */
  	__NR_sigreturn,
  	0x80cd,		/* int $0x80 */
  };
  
  static const struct {
  	u8  movl;
  	u32 val;
  	u16 int80;
  	u8  pad;
  } __attribute__((packed)) rt_retcode = {
  	0xb8,		/* movl $..., %eax */
  	__NR_rt_sigreturn,
  	0x80cd,		/* int $0x80 */
  	0
  };

  static int

  __setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
  	      struct pt_regs *regs)

  {

  	struct sigframe __user *frame;

  	void __user *restorer;

  	int err = 0;

  	void __user *fpstate = NULL;

  	frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);

  
  	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))

  		return -EFAULT;

  	if (__put_user(sig, &frame->sig))

  		return -EFAULT;

  	if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))

  		return -EFAULT;

  
  	if (_NSIG_WORDS > 1) {

  		if (__copy_to_user(&frame->extramask, &set->sig[1],
  				   sizeof(frame->extramask)))

  			return -EFAULT;

  	}

  	if (current->mm->context.vdso)

  		restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);

  	else

  		restorer = &frame->retcode;

  	if (ka->sa.sa_flags & SA_RESTORER)
  		restorer = ka->sa.sa_restorer;
  
  	/* Set up to return from userspace.  */
  	err |= __put_user(restorer, &frame->pretcode);

  	/*

  	 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80

  	 *
  	 * WE DO NOT USE IT ANY MORE! It's only left here for historical
  	 * reasons and because gdb uses it as a signature to notice
  	 * signal handler stack frames.
  	 */

  	err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);

  
  	if (err)

  		return -EFAULT;

  
  	/* Set up registers for signal handler */

  	regs->sp = (unsigned long)frame;
  	regs->ip = (unsigned long)ka->sa.sa_handler;
  	regs->ax = (unsigned long)sig;

  	regs->dx = 0;
  	regs->cx = 0;

  	regs->ds = __USER_DS;
  	regs->es = __USER_DS;
  	regs->ss = __USER_DS;
  	regs->cs = __USER_CS;

  	return 0;

  }

  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;

  	void __user *restorer;

  	int err = 0;

  	void __user *fpstate = NULL;

  	frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);

  
  	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))

  		return -EFAULT;

  	put_user_try {
  		put_user_ex(sig, &frame->sig);
  		put_user_ex(&frame->info, &frame->pinfo);
  		put_user_ex(&frame->uc, &frame->puc);
  		err |= copy_siginfo_to_user(&frame->info, info);
  
  		/* Create the ucontext.  */
  		if (cpu_has_xsave)
  			put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
  		else
  			put_user_ex(0, &frame->uc.uc_flags);
  		put_user_ex(0, &frame->uc.uc_link);
  		put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
  		put_user_ex(sas_ss_flags(regs->sp),
  			    &frame->uc.uc_stack.ss_flags);
  		put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
  		err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
  					regs, set->sig[0]);
  		err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
  
  		/* Set up to return from userspace.  */
  		restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
  		if (ka->sa.sa_flags & SA_RESTORER)
  			restorer = ka->sa.sa_restorer;
  		put_user_ex(restorer, &frame->pretcode);
  
  		/*
  		 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
  		 *
  		 * WE DO NOT USE IT ANY MORE! It's only left here for historical
  		 * reasons and because gdb uses it as a signature to notice
  		 * signal handler stack frames.
  		 */
  		put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
  	} put_user_catch(err);

  
  	if (err)

  		return -EFAULT;

  
  	/* Set up registers for signal handler */

  	regs->sp = (unsigned long)frame;
  	regs->ip = (unsigned long)ka->sa.sa_handler;

  	regs->ax = (unsigned long)sig;

  	regs->dx = (unsigned long)&frame->info;
  	regs->cx = (unsigned long)&frame->uc;

  	regs->ds = __USER_DS;
  	regs->es = __USER_DS;
  	regs->ss = __USER_DS;
  	regs->cs = __USER_CS;

  	return 0;

  }

  #else /* !CONFIG_X86_32 */

  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;
  	void __user *fp = NULL;
  	int err = 0;
  	struct task_struct *me = current;

  	frame = get_sigframe(ka, regs, sizeof(struct rt_sigframe), &fp);

  
  	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
  		return -EFAULT;
  
  	if (ka->sa.sa_flags & SA_SIGINFO) {
  		if (copy_siginfo_to_user(&frame->info, info))
  			return -EFAULT;
  	}

  	put_user_try {
  		/* Create the ucontext.  */
  		if (cpu_has_xsave)
  			put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
  		else
  			put_user_ex(0, &frame->uc.uc_flags);
  		put_user_ex(0, &frame->uc.uc_link);
  		put_user_ex(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
  		put_user_ex(sas_ss_flags(regs->sp),
  			    &frame->uc.uc_stack.ss_flags);
  		put_user_ex(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
  		err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
  		err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
  
  		/* Set up to return from userspace.  If provided, use a stub
  		   already in userspace.  */
  		/* x86-64 should always use SA_RESTORER. */
  		if (ka->sa.sa_flags & SA_RESTORER) {
  			put_user_ex(ka->sa.sa_restorer, &frame->pretcode);
  		} else {
  			/* could use a vstub here */
  			err |= -EFAULT;
  		}
  	} put_user_catch(err);

  
  	if (err)
  		return -EFAULT;
  
  	/* Set up registers for signal handler */
  	regs->di = sig;
  	/* In case the signal handler was declared without prototypes */
  	regs->ax = 0;
  
  	/* This also works for non SA_SIGINFO handlers because they expect the
  	   next argument after the signal number on the stack. */
  	regs->si = (unsigned long)&frame->info;
  	regs->dx = (unsigned long)&frame->uc;
  	regs->ip = (unsigned long) ka->sa.sa_handler;
  
  	regs->sp = (unsigned long)frame;
  
  	/* Set up the CS register to run signal handlers in 64-bit mode,
  	   even if the handler happens to be interrupting 32-bit code. */
  	regs->cs = __USER_CS;
  
  	return 0;
  }
  #endif /* CONFIG_X86_32 */

  #ifdef CONFIG_X86_32

  /*
   * Atomically swap in the new signal mask, and wait for a signal.
   */
  asmlinkage int
  sys_sigsuspend(int history0, int history1, old_sigset_t mask)
  {

  	sigset_t blocked;

  	current->saved_sigmask = current->blocked;

  
  	mask &= _BLOCKABLE;
  	siginitset(&blocked, mask);
  	set_current_blocked(&blocked);

  
  	current->state = TASK_INTERRUPTIBLE;
  	schedule();

  	set_restore_sigmask();

  	return -ERESTARTNOHAND;
  }
  
  asmlinkage int
  sys_sigaction(int sig, const struct old_sigaction __user *act,
  	      struct old_sigaction __user *oact)
  {
  	struct k_sigaction new_ka, old_ka;

  	int ret = 0;

  
  	if (act) {
  		old_sigset_t mask;

  		if (!access_ok(VERIFY_READ, act, sizeof(*act)))

  			return -EFAULT;

  		get_user_try {
  			get_user_ex(new_ka.sa.sa_handler, &act->sa_handler);
  			get_user_ex(new_ka.sa.sa_flags, &act->sa_flags);
  			get_user_ex(mask, &act->sa_mask);
  			get_user_ex(new_ka.sa.sa_restorer, &act->sa_restorer);
  		} get_user_catch(ret);
  
  		if (ret)
  			return -EFAULT;

  		siginitset(&new_ka.sa.sa_mask, mask);
  	}
  
  	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  
  	if (!ret && oact) {

  		if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))

  			return -EFAULT;

  		put_user_try {
  			put_user_ex(old_ka.sa.sa_handler, &oact->sa_handler);
  			put_user_ex(old_ka.sa.sa_flags, &oact->sa_flags);
  			put_user_ex(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
  			put_user_ex(old_ka.sa.sa_restorer, &oact->sa_restorer);
  		} put_user_catch(ret);
  
  		if (ret)
  			return -EFAULT;

  	}
  
  	return ret;
  }

  #endif /* CONFIG_X86_32 */

  long

  sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  		struct pt_regs *regs)
  {
  	return do_sigaltstack(uss, uoss, regs->sp);
  }

  
  /*
   * Do a signal return; undo the signal stack.
   */

  #ifdef CONFIG_X86_32

  unsigned long sys_sigreturn(struct pt_regs *regs)

  {
  	struct sigframe __user *frame;

  	unsigned long ax;
  	sigset_t set;

  	frame = (struct sigframe __user *)(regs->sp - 8);
  
  	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  		goto badframe;
  	if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
  		&& __copy_from_user(&set.sig[1], &frame->extramask,
  				    sizeof(frame->extramask))))
  		goto badframe;
  
  	sigdelsetmask(&set, ~_BLOCKABLE);

  	set_current_blocked(&set);

  
  	if (restore_sigcontext(regs, &frame->sc, &ax))
  		goto badframe;
  	return ax;
  
  badframe:

  	signal_fault(regs, frame, "sigreturn");

  
  	return 0;
  }

  #endif /* CONFIG_X86_32 */

  long sys_rt_sigreturn(struct pt_regs *regs)

  {
  	struct rt_sigframe __user *frame;
  	unsigned long ax;
  	sigset_t set;
  
  	frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
  	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);

  	set_current_blocked(&set);

  
  	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
  		goto badframe;
  
  	if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
  		goto badframe;
  
  	return ax;
  
  badframe:
  	signal_fault(regs, frame, "rt_sigreturn");
  	return 0;
  }

  /*

   * OK, we're invoking a handler:
   */

  static int signr_convert(int sig)
  {

  #ifdef CONFIG_X86_32

  	struct thread_info *info = current_thread_info();
  
  	if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
  		return info->exec_domain->signal_invmap[sig];

  #endif /* CONFIG_X86_32 */

  	return sig;
  }

  #ifdef CONFIG_X86_32

  #define is_ia32	1

  #define ia32_setup_frame	__setup_frame
  #define ia32_setup_rt_frame	__setup_rt_frame

  #else /* !CONFIG_X86_32 */
  
  #ifdef CONFIG_IA32_EMULATION
  #define is_ia32	test_thread_flag(TIF_IA32)
  #else /* !CONFIG_IA32_EMULATION */
  #define is_ia32	0
  #endif /* CONFIG_IA32_EMULATION */

  int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
  		sigset_t *set, struct pt_regs *regs);
  int ia32_setup_frame(int sig, struct k_sigaction *ka,
  		sigset_t *set, struct pt_regs *regs);

  #endif /* CONFIG_X86_32 */

  static int

  setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,

  		struct pt_regs *regs)

  {

  	int usig = signr_convert(sig);

  	sigset_t *set = &current->blocked;

  	int ret;

  	if (current_thread_info()->status & TS_RESTORE_SIGMASK)
  		set = &current->saved_sigmask;

  	/* Set up the stack frame */

  	if (is_ia32) {
  		if (ka->sa.sa_flags & SA_SIGINFO)

  			ret = ia32_setup_rt_frame(usig, ka, info, set, regs);

  		else

  			ret = ia32_setup_frame(usig, ka, set, regs);

  	} else
  		ret = __setup_rt_frame(sig, ka, info, set, regs);

  	if (ret) {
  		force_sigsegv(sig, current);
  		return -EFAULT;
  	}

  	current_thread_info()->status &= ~TS_RESTORE_SIGMASK;

  	return ret;
  }
  
  static int

  handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,

  		struct pt_regs *regs)

  {

  	int ret;

  	/* Are we from a system call? */

  	if (syscall_get_nr(current, regs) >= 0) {

  		/* If so, check system call restarting.. */

  		switch (syscall_get_error(current, regs)) {

  		case -ERESTART_RESTARTBLOCK:
  		case -ERESTARTNOHAND:
  			regs->ax = -EINTR;
  			break;
  
  		case -ERESTARTSYS:
  			if (!(ka->sa.sa_flags & SA_RESTART)) {

  				regs->ax = -EINTR;

  				break;

  			}
  		/* fallthrough */
  		case -ERESTARTNOINTR:
  			regs->ax = regs->orig_ax;
  			regs->ip -= 2;
  			break;

  		}
  	}
  
  	/*

  	 * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
  	 * flag so that register information in the sigcontext is correct.

  	 */

  	if (unlikely(regs->flags & X86_EFLAGS_TF) &&

  	    likely(test_and_clear_thread_flag(TIF_FORCED_TF)))

  		regs->flags &= ~X86_EFLAGS_TF;

  	ret = setup_rt_frame(sig, ka, info, regs);

  	if (ret)
  		return ret;

  	/*
  	 * Clear the direction flag as per the ABI for function entry.
  	 */
  	regs->flags &= ~X86_EFLAGS_DF;
  
  	/*
  	 * Clear TF when entering the signal handler, but
  	 * notify any tracer that was single-stepping it.
  	 * The tracer may want to single-step inside the
  	 * handler too.
  	 */
  	regs->flags &= ~X86_EFLAGS_TF;

  	block_sigmask(ka, sig);

  	tracehook_signal_handler(sig, info, ka, regs,
  				 test_thread_flag(TIF_SINGLESTEP));

  	return 0;

  }

  #ifdef CONFIG_X86_32

  #define NR_restart_syscall	__NR_restart_syscall

  #else /* !CONFIG_X86_32 */
  #define NR_restart_syscall	\
  	test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
  #endif /* CONFIG_X86_32 */

  /*
   * 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.
   */

  static void do_signal(struct pt_regs *regs)

  {

  	struct k_sigaction ka;

  	siginfo_t info;
  	int signr;

  
  	/*

  	 * 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.
  	 * X86_32: vm86 regs switched out by assembly code before reaching
  	 * here, so testing against kernel CS suffices.

  	 */

  	if (!user_mode(regs))

  		return;

  	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
  	if (signr > 0) {

  		/* Whee! Actually deliver the signal.  */

  		handle_signal(signr, &info, &ka, regs);

  		return;

  	}

  	/* Did we come from a system call? */

  	if (syscall_get_nr(current, regs) >= 0) {

  		/* Restart the system call - no handlers present */

  		switch (syscall_get_error(current, regs)) {

  		case -ERESTARTNOHAND:
  		case -ERESTARTSYS:
  		case -ERESTARTNOINTR:

  			regs->ax = regs->orig_ax;
  			regs->ip -= 2;

  			break;
  
  		case -ERESTART_RESTARTBLOCK:

  			regs->ax = NR_restart_syscall;

  			regs->ip -= 2;

  			break;

  		}
  	}

  	/*
  	 * If there's no signal to deliver, we just put the saved sigmask
  	 * back.
  	 */

  	if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
  		current_thread_info()->status &= ~TS_RESTORE_SIGMASK;

  		set_current_blocked(&current->saved_sigmask);

  	}

  }
  
  /*
   * notification of userspace execution resumption

   * - triggered by the TIF_WORK_MASK flags

   */

  void
  do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)

  {

  #ifdef CONFIG_X86_MCE

  	/* notify userspace of pending MCEs */
  	if (thread_info_flags & _TIF_MCE_NOTIFY)

  		mce_notify_process();

  #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */

  	/* deal with pending signal delivery */

  	if (thread_info_flags & _TIF_SIGPENDING)

  		do_signal(regs);

  	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
  		clear_thread_flag(TIF_NOTIFY_RESUME);
  		tracehook_notify_resume(regs);

  		if (current->replacement_session_keyring)
  			key_replace_session_keyring();

  	}

  	if (thread_info_flags & _TIF_USER_RETURN_NOTIFY)
  		fire_user_return_notifiers();

  #ifdef CONFIG_X86_32

  	clear_thread_flag(TIF_IRET);

  #endif /* CONFIG_X86_32 */

  }

  
  void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
  {
  	struct task_struct *me = current;
  
  	if (show_unhandled_signals && printk_ratelimit()) {

  		printk("%s"

  		       "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",

  		       task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,

  		       me->comm, me->pid, where, frame,
  		       regs->ip, regs->sp, regs->orig_ax);
  		print_vma_addr(" in ", regs->ip);
  		printk(KERN_CONT "
  ");
  	}
  
  	force_sig(SIGSEGV, me);
  }