arch/tile/kernel/signal.c - linux - Git at Google

 /*
  * Copyright (C) 1991, 1992  Linus Torvalds
  * Copyright 2010 Tilera Corporation. All Rights Reserved.
  *
  *   This program is free software; you can redistribute it and/or
  *   modify it under the terms of the GNU General Public License
  *   as published by the Free Software Foundation, version 2.
  *
  *   This program is distributed in the hope that it will be useful, but
  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  *   NON INFRINGEMENT.  See the GNU General Public License for
  *   more details.
  */

 #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/unistd.h>
 #include <linux/stddef.h>
 #include <linux/personality.h>
 #include <linux/suspend.h>
 #include <linux/ptrace.h>
 #include <linux/elf.h>
 #include <linux/compat.h>
 #include <linux/syscalls.h>
 #include <linux/uaccess.h>
 #include <asm/processor.h>
 #include <asm/ucontext.h>
 #include <asm/sigframe.h>
 #include <asm/syscalls.h>
 #include <arch/interrupts.h>

 #define DEBUG_SIG 0

 SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss,
 		stack_t __user *, uoss)
 {
 	return do_sigaltstack(uss, uoss, current_pt_regs()->sp);
 }


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

 int restore_sigcontext(struct pt_regs *regs,
 		       struct sigcontext __user *sc)
 {
 	int err = 0;
 	int i;

 	/* Always make any pending restarted system calls return -EINTR */
 	current_thread_info()->restart_block.fn = do_no_restart_syscall;

 	/*
 	 * Enforce that sigcontext is like pt_regs, and doesn't mess
 	 * up our stack alignment rules.
 	 */
 	BUILD_BUG_ON(sizeof(struct sigcontext) != sizeof(struct pt_regs));
 	BUILD_BUG_ON(sizeof(struct sigcontext) % 8 != 0);

 	for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
 		err |= __get_user(regs->regs[i], &sc->gregs[i]);

 	/* Ensure that the PL is always set to USER_PL. */
 	regs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(regs->ex1));

 	regs->faultnum = INT_SWINT_1_SIGRETURN;

 	return err;
 }

 void signal_fault(const char *type, struct pt_regs *regs,
 		  void __user *frame, int sig)
 {
 	trace_unhandled_signal(type, regs, (unsigned long)frame, SIGSEGV);
 	force_sigsegv(sig, current);
 }

 /* The assembly shim for this function arranges to ignore the return value. */
 SYSCALL_DEFINE0(rt_sigreturn)
 {
 	struct pt_regs *regs = current_pt_regs();
 	struct rt_sigframe __user *frame =
 		(struct rt_sigframe __user *)(regs->sp);
 	sigset_t set;

 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 		goto badframe;
 	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 		goto badframe;

 	set_current_blocked(&set);

 	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 		goto badframe;

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

 	return 0;

 badframe:
 	signal_fault("bad sigreturn frame", regs, frame, 0);
 	return 0;
 }

 /*
  * Set up a signal frame.
  */

 int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 {
 	int i, err = 0;

 	for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
 		err |= __put_user(regs->regs[i], &sc->gregs[i]);

 	return err;
 }

 /*
  * Determine which stack to use..
  */
 static inline void __user *get_sigframe(struct k_sigaction *ka,
 					struct pt_regs *regs,
 					size_t frame_size)
 {
 	unsigned long sp;

 	/* Default to using normal stack */
 	sp = regs->sp;

 	/*
 	 * 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 (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 		return (void __user __force *)-1UL;

 	/* This is the X/Open sanctioned signal stack switching.  */
 	if (ka->sa.sa_flags & SA_ONSTACK) {
 		if (sas_ss_flags(sp) == 0)
 			sp = current->sas_ss_sp + current->sas_ss_size;
 	}

 	sp -= frame_size;
 	/*
 	 * Align the stack pointer according to the TILE ABI,
 	 * i.e. so that on function entry (sp & 15) == 0.
 	 */
 	sp &= -16UL;
 	return (void __user *) sp;
 }

 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 			   sigset_t *set, struct pt_regs *regs)
 {
 	unsigned long restorer;
 	struct rt_sigframe __user *frame;
 	int err = 0;
 	int usig;

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

 	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 		goto give_sigsegv;

 	usig = current_thread_info()->exec_domain
 		&& current_thread_info()->exec_domain->signal_invmap
 		&& sig < 32
 		? current_thread_info()->exec_domain->signal_invmap[sig]
 		: sig;

 	/* Always write at least the signal number for the stack backtracer. */
 	if (ka->sa.sa_flags & SA_SIGINFO) {
 		/* At sigreturn time, restore the callee-save registers too. */
 		err |= copy_siginfo_to_user(&frame->info, info);
 		regs->flags |= PT_FLAGS_RESTORE_REGS;
 	} else {
 		err |= __put_user(info->si_signo, &frame->info.si_signo);
 	}

 	/* Create the ucontext.  */
 	err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
 	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 give_sigsegv;

 	restorer = VDSO_BASE;
 	if (ka->sa.sa_flags & SA_RESTORER)
 		restorer = (unsigned long) ka->sa.sa_restorer;

 	/*
 	 * Set up registers for signal handler.
 	 * Registers that we don't modify keep the value they had from
 	 * user-space at the time we took the signal.
 	 * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
 	 * since some things rely on this (e.g. glibc's debug/segfault.c).
 	 */
 	regs->pc = (unsigned long) ka->sa.sa_handler;
 	regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
 	regs->sp = (unsigned long) frame;
 	regs->lr = restorer;
 	regs->regs[0] = (unsigned long) usig;
 	regs->regs[1] = (unsigned long) &frame->info;
 	regs->regs[2] = (unsigned long) &frame->uc;
 	regs->flags |= PT_FLAGS_CALLER_SAVES;
 	return 0;

 give_sigsegv:
 	signal_fault("bad setup frame", regs, frame, sig);
 	return -EFAULT;
 }

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

 static void handle_signal(unsigned long sig, siginfo_t *info,
 			 struct k_sigaction *ka,
 			 struct pt_regs *regs)
 {
 	sigset_t *oldset = sigmask_to_save();
 	int ret;

 	/* Are we from a system call? */
 	if (regs->faultnum == INT_SWINT_1) {
 		/* If so, check system call restarting.. */
 		switch (regs->regs[0]) {
 		case -ERESTART_RESTARTBLOCK:
 		case -ERESTARTNOHAND:
 			regs->regs[0] = -EINTR;
 			break;

 		case -ERESTARTSYS:
 			if (!(ka->sa.sa_flags & SA_RESTART)) {
 				regs->regs[0] = -EINTR;
 				break;
 			}
 			/* fallthrough */
 		case -ERESTARTNOINTR:
 			/* Reload caller-saves to restore r0..r5 and r10. */
 			regs->flags |= PT_FLAGS_CALLER_SAVES;
 			regs->regs[0] = regs->orig_r0;
 			regs->pc -= 8;
 		}
 	}

 	/* Set up the stack frame */
 #ifdef CONFIG_COMPAT
 	if (is_compat_task())
 		ret = compat_setup_rt_frame(sig, ka, info, oldset, regs);
 	else
 #endif
 		ret = setup_rt_frame(sig, ka, info, oldset, regs);
 	if (ret)
 		return;
 	signal_delivered(sig, info, ka, regs,
 			test_thread_flag(TIF_SINGLESTEP));
 }

 /*
  * 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.
  */
 void do_signal(struct pt_regs *regs)
 {
 	siginfo_t info;
 	int signr;
 	struct k_sigaction ka;

 	/*
 	 * i386 will check if we're coming from kernel mode and bail out
 	 * here.  In my experience this just turns weird crashes into
 	 * weird spin-hangs.  But if we find a case where this seems
 	 * helpful, we can reinstate the check on "!user_mode(regs)".
 	 */

 	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 	if (signr > 0) {
 		/* Whee! Actually deliver the signal.  */
 		handle_signal(signr, &info, &ka, regs);
 		goto done;
 	}

 	/* Did we come from a system call? */
 	if (regs->faultnum == INT_SWINT_1) {
 		/* Restart the system call - no handlers present */
 		switch (regs->regs[0]) {
 		case -ERESTARTNOHAND:
 		case -ERESTARTSYS:
 		case -ERESTARTNOINTR:
 			regs->flags |= PT_FLAGS_CALLER_SAVES;
 			regs->regs[0] = regs->orig_r0;
 			regs->pc -= 8;
 			break;

 		case -ERESTART_RESTARTBLOCK:
 			regs->flags |= PT_FLAGS_CALLER_SAVES;
 			regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
 			regs->pc -= 8;
 			break;
 		}
 	}

 	/* If there's no signal to deliver, just put the saved sigmask back. */
 	restore_saved_sigmask();

 done:
 	/* Avoid double syscall restart if there are nested signals. */
 	regs->faultnum = INT_SWINT_1_SIGRETURN;
 }

 int show_unhandled_signals = 1;

 static int __init crashinfo(char *str)
 {
 	unsigned long val;
 	const char *word;

 	if (*str == '\0')
 		val = 2;
 	else if (*str != '=' || strict_strtoul(++str, 0, &val) != 0)
 		return 0;
 	show_unhandled_signals = val;
 	switch (show_unhandled_signals) {
 	case 0:
 		word = "No";
 		break;
 	case 1:
 		word = "One-line";
 		break;
 	default:
 		word = "Detailed";
 		break;
 	}
 	pr_info("%s crash reports will be generated on the console\n", word);
 	return 1;
 }
 __setup("crashinfo", crashinfo);

 static void dump_mem(void __user *address)
 {
 	void __user *addr;
 	enum { region_size = 256, bytes_per_line = 16 };
 	int i, j, k;
 	int found_readable_mem = 0;

 	pr_err("\n");
 	if (!access_ok(VERIFY_READ, address, 1)) {
 		pr_err("Not dumping at address 0x%lx (kernel address)\n",
 		       (unsigned long)address);
 		return;
 	}

 	addr = (void __user *)
 		(((unsigned long)address & -bytes_per_line) - region_size/2);
 	if (addr > address)
 		addr = NULL;
 	for (i = 0; i < region_size;
 	     addr += bytes_per_line, i += bytes_per_line) {
 		unsigned char buf[bytes_per_line];
 		char line[100];
 		if (copy_from_user(buf, addr, bytes_per_line))
 			continue;
 		if (!found_readable_mem) {
 			pr_err("Dumping memory around address 0x%lx:\n",
 			       (unsigned long)address);
 			found_readable_mem = 1;
 		}
 		j = sprintf(line, REGFMT":", (unsigned long)addr);
 		for (k = 0; k < bytes_per_line; ++k)
 			j += sprintf(&line[j], " %02x", buf[k]);
 		pr_err("%s\n", line);
 	}
 	if (!found_readable_mem)
 		pr_err("No readable memory around address 0x%lx\n",
 		       (unsigned long)address);
 }

 void trace_unhandled_signal(const char *type, struct pt_regs *regs,
 			    unsigned long address, int sig)
 {
 	struct task_struct *tsk = current;

 	if (show_unhandled_signals == 0)
 		return;

 	/* If the signal is handled, don't show it here. */
 	if (!is_global_init(tsk)) {
 		void __user *handler =
 			tsk->sighand->action[sig-1].sa.sa_handler;
 		if (handler != SIG_IGN && handler != SIG_DFL)
 			return;
 	}

 	/* Rate-limit the one-line output, not the detailed output. */
 	if (show_unhandled_signals <= 1 && !printk_ratelimit())
 		return;

 	printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d",
 	       task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 	       tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig);

 	print_vma_addr(KERN_CONT " in ", regs->pc);

 	printk(KERN_CONT "\n");

 	if (show_unhandled_signals > 1) {
 		switch (sig) {
 		case SIGILL:
 		case SIGFPE:
 		case SIGSEGV:
 		case SIGBUS:
 			pr_err("User crash: signal %d,"
 			       " trap %ld, address 0x%lx\n",
 			       sig, regs->faultnum, address);
 			show_regs(regs);
 			dump_mem((void __user *)address);
 			break;
 		default:
 			pr_err("User crash: signal %d, trap %ld\n",
 			       sig, regs->faultnum);
 			break;
 		}
 	}
 }
	/*
	* Copyright (C) 1991, 1992 Linus Torvalds
	* Copyright 2010 Tilera Corporation. All Rights Reserved.
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation, version 2.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
	* NON INFRINGEMENT. See the GNU General Public License for
	* more details.
	*/

	#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/unistd.h>
	#include <linux/stddef.h>
	#include <linux/personality.h>
	#include <linux/suspend.h>
	#include <linux/ptrace.h>
	#include <linux/elf.h>
	#include <linux/compat.h>
	#include <linux/syscalls.h>
	#include <linux/uaccess.h>
	#include <asm/processor.h>
	#include <asm/ucontext.h>
	#include <asm/sigframe.h>
	#include <asm/syscalls.h>
	#include <arch/interrupts.h>

	#define DEBUG_SIG 0

	SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss,
	stack_t __user *, uoss)
	{
	return do_sigaltstack(uss, uoss, current_pt_regs()->sp);
	}


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

	int restore_sigcontext(struct pt_regs *regs,
	struct sigcontext __user *sc)
	{
	int err = 0;
	int i;

	/* Always make any pending restarted system calls return -EINTR */
	current_thread_info()->restart_block.fn = do_no_restart_syscall;

	/*
	* Enforce that sigcontext is like pt_regs, and doesn't mess
	* up our stack alignment rules.
	*/
	BUILD_BUG_ON(sizeof(struct sigcontext) != sizeof(struct pt_regs));
	BUILD_BUG_ON(sizeof(struct sigcontext) % 8 != 0);

	for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
	err \|= __get_user(regs->regs[i], &sc->gregs[i]);

	/* Ensure that the PL is always set to USER_PL. */
	regs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(regs->ex1));

	regs->faultnum = INT_SWINT_1_SIGRETURN;

	return err;
	}

	void signal_fault(const char type, struct pt_regs regs,
	void __user *frame, int sig)
	{
	trace_unhandled_signal(type, regs, (unsigned long)frame, SIGSEGV);
	force_sigsegv(sig, current);
	}

	/* The assembly shim for this function arranges to ignore the return value. */
	SYSCALL_DEFINE0(rt_sigreturn)
	{
	struct pt_regs *regs = current_pt_regs();
	struct rt_sigframe __user *frame =
	(struct rt_sigframe __user *)(regs->sp);
	sigset_t set;

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
	goto badframe;
	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
	goto badframe;

	set_current_blocked(&set);

	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
	goto badframe;

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

	return 0;

	badframe:
	signal_fault("bad sigreturn frame", regs, frame, 0);
	return 0;
	}

	/*
	* Set up a signal frame.
	*/

	int setup_sigcontext(struct sigcontext __user sc, struct pt_regs regs)
	{
	int i, err = 0;

	for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
	err \|= __put_user(regs->regs[i], &sc->gregs[i]);

	return err;
	}

	/*
	* Determine which stack to use..
	*/
	static inline void __user get_sigframe(struct k_sigaction ka,
	struct pt_regs *regs,
	size_t frame_size)
	{
	unsigned long sp;

	/* Default to using normal stack */
	sp = regs->sp;

	/*
	* 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 (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
	return (void __user __force *)-1UL;

	/* This is the X/Open sanctioned signal stack switching. */
	if (ka->sa.sa_flags & SA_ONSTACK) {
	if (sas_ss_flags(sp) == 0)
	sp = current->sas_ss_sp + current->sas_ss_size;
	}

	sp -= frame_size;
	/*
	* Align the stack pointer according to the TILE ABI,
	* i.e. so that on function entry (sp & 15) == 0.
	*/
	sp &= -16UL;
	return (void __user *) sp;
	}

	static int setup_rt_frame(int sig, struct k_sigaction ka, siginfo_t info,
	sigset_t set, struct pt_regs regs)
	{
	unsigned long restorer;
	struct rt_sigframe __user *frame;
	int err = 0;
	int usig;

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

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
	goto give_sigsegv;

	usig = current_thread_info()->exec_domain
	&& current_thread_info()->exec_domain->signal_invmap
	&& sig < 32
	? current_thread_info()->exec_domain->signal_invmap[sig]
	: sig;

	/* Always write at least the signal number for the stack backtracer. */
	if (ka->sa.sa_flags & SA_SIGINFO) {
	/* At sigreturn time, restore the callee-save registers too. */
	err \|= copy_siginfo_to_user(&frame->info, info);
	regs->flags \|= PT_FLAGS_RESTORE_REGS;
	} else {
	err \|= __put_user(info->si_signo, &frame->info.si_signo);
	}

	/* Create the ucontext. */
	err \|= __clear_user(&frame->save_area, sizeof(frame->save_area));
	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 give_sigsegv;

	restorer = VDSO_BASE;
	if (ka->sa.sa_flags & SA_RESTORER)
	restorer = (unsigned long) ka->sa.sa_restorer;

	/*
	* Set up registers for signal handler.
	* Registers that we don't modify keep the value they had from
	* user-space at the time we took the signal.
	* We always pass siginfo and mcontext, regardless of SA_SIGINFO,
	* since some things rely on this (e.g. glibc's debug/segfault.c).
	*/
	regs->pc = (unsigned long) ka->sa.sa_handler;
	regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
	regs->sp = (unsigned long) frame;
	regs->lr = restorer;
	regs->regs[0] = (unsigned long) usig;
	regs->regs[1] = (unsigned long) &frame->info;
	regs->regs[2] = (unsigned long) &frame->uc;
	regs->flags \|= PT_FLAGS_CALLER_SAVES;
	return 0;

	give_sigsegv:
	signal_fault("bad setup frame", regs, frame, sig);
	return -EFAULT;
	}

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

	static void handle_signal(unsigned long sig, siginfo_t *info,
	struct k_sigaction *ka,
	struct pt_regs *regs)
	{
	sigset_t *oldset = sigmask_to_save();
	int ret;

	/* Are we from a system call? */
	if (regs->faultnum == INT_SWINT_1) {
	/* If so, check system call restarting.. */
	switch (regs->regs[0]) {
	case -ERESTART_RESTARTBLOCK:
	case -ERESTARTNOHAND:
	regs->regs[0] = -EINTR;
	break;

	case -ERESTARTSYS:
	if (!(ka->sa.sa_flags & SA_RESTART)) {
	regs->regs[0] = -EINTR;
	break;
	}
	/* fallthrough */
	case -ERESTARTNOINTR:
	/* Reload caller-saves to restore r0..r5 and r10. */
	regs->flags \|= PT_FLAGS_CALLER_SAVES;
	regs->regs[0] = regs->orig_r0;
	regs->pc -= 8;
	}
	}

	/* Set up the stack frame */
	#ifdef CONFIG_COMPAT
	if (is_compat_task())
	ret = compat_setup_rt_frame(sig, ka, info, oldset, regs);
	else
	#endif
	ret = setup_rt_frame(sig, ka, info, oldset, regs);
	if (ret)
	return;
	signal_delivered(sig, info, ka, regs,
	test_thread_flag(TIF_SINGLESTEP));
	}

	/*
	* 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.
	*/
	void do_signal(struct pt_regs *regs)
	{
	siginfo_t info;
	int signr;
	struct k_sigaction ka;

	/*
	* i386 will check if we're coming from kernel mode and bail out
	* here. In my experience this just turns weird crashes into
	* weird spin-hangs. But if we find a case where this seems
	* helpful, we can reinstate the check on "!user_mode(regs)".
	*/

	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
	if (signr > 0) {
	/* Whee! Actually deliver the signal. */
	handle_signal(signr, &info, &ka, regs);
	goto done;
	}

	/* Did we come from a system call? */
	if (regs->faultnum == INT_SWINT_1) {
	/* Restart the system call - no handlers present */
	switch (regs->regs[0]) {
	case -ERESTARTNOHAND:
	case -ERESTARTSYS:
	case -ERESTARTNOINTR:
	regs->flags \|= PT_FLAGS_CALLER_SAVES;
	regs->regs[0] = regs->orig_r0;
	regs->pc -= 8;
	break;

	case -ERESTART_RESTARTBLOCK:
	regs->flags \|= PT_FLAGS_CALLER_SAVES;
	regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
	regs->pc -= 8;
	break;
	}
	}

	/* If there's no signal to deliver, just put the saved sigmask back. */
	restore_saved_sigmask();

	done:
	/* Avoid double syscall restart if there are nested signals. */
	regs->faultnum = INT_SWINT_1_SIGRETURN;
	}

	int show_unhandled_signals = 1;

	static int __init crashinfo(char *str)
	{
	unsigned long val;
	const char *word;

	if (*str == '\0')
	val = 2;
	else if (*str != '=' \|\| strict_strtoul(++str, 0, &val) != 0)
	return 0;
	show_unhandled_signals = val;
	switch (show_unhandled_signals) {
	case 0:
	word = "No";
	break;
	case 1:
	word = "One-line";
	break;
	default:
	word = "Detailed";
	break;
	}
	pr_info("%s crash reports will be generated on the console\n", word);
	return 1;
	}
	__setup("crashinfo", crashinfo);

	static void dump_mem(void __user *address)
	{
	void __user *addr;
	enum { region_size = 256, bytes_per_line = 16 };
	int i, j, k;
	int found_readable_mem = 0;

	pr_err("\n");
	if (!access_ok(VERIFY_READ, address, 1)) {
	pr_err("Not dumping at address 0x%lx (kernel address)\n",
	(unsigned long)address);
	return;
	}

	addr = (void __user *)
	(((unsigned long)address & -bytes_per_line) - region_size/2);
	if (addr > address)
	addr = NULL;
	for (i = 0; i < region_size;
	addr += bytes_per_line, i += bytes_per_line) {
	unsigned char buf[bytes_per_line];
	char line[100];
	if (copy_from_user(buf, addr, bytes_per_line))
	continue;
	if (!found_readable_mem) {
	pr_err("Dumping memory around address 0x%lx:\n",
	(unsigned long)address);
	found_readable_mem = 1;
	}
	j = sprintf(line, REGFMT":", (unsigned long)addr);
	for (k = 0; k < bytes_per_line; ++k)
	j += sprintf(&line[j], " %02x", buf[k]);
	pr_err("%s\n", line);
	}
	if (!found_readable_mem)
	pr_err("No readable memory around address 0x%lx\n",
	(unsigned long)address);
	}

	void trace_unhandled_signal(const char type, struct pt_regs regs,
	unsigned long address, int sig)
	{
	struct task_struct *tsk = current;

	if (show_unhandled_signals == 0)
	return;

	/* If the signal is handled, don't show it here. */
	if (!is_global_init(tsk)) {
	void __user *handler =
	tsk->sighand->action[sig-1].sa.sa_handler;
	if (handler != SIG_IGN && handler != SIG_DFL)
	return;
	}

	/* Rate-limit the one-line output, not the detailed output. */
	if (show_unhandled_signals <= 1 && !printk_ratelimit())
	return;

	printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d",
	task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
	tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig);

	print_vma_addr(KERN_CONT " in ", regs->pc);

	printk(KERN_CONT "\n");

	if (show_unhandled_signals > 1) {
	switch (sig) {
	case SIGILL:
	case SIGFPE:
	case SIGSEGV:
	case SIGBUS:
	pr_err("User crash: signal %d,"
	" trap %ld, address 0x%lx\n",
	sig, regs->faultnum, address);
	show_regs(regs);
	dump_mem((void __user *)address);
	break;
	default:
	pr_err("User crash: signal %d, trap %ld\n",
	sig, regs->faultnum);
	break;
	}
	}
	}