arch/sparc/kernel/traps_32.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * arch/sparc/kernel/traps.c
  *
  * Copyright 1995, 2008 David S. Miller (davem@davemloft.net)
  * Copyright 2000 Jakub Jelinek (jakub@redhat.com)
  */

 /*
  * I hate traps on the sparc, grrr...
  */

 #include <linux/cpu.h>
 #include <linux/sched/mm.h>
 #include <linux/sched/debug.h>
 #include <linux/mm_types.h>
 #include <linux/kernel.h>
 #include <linux/signal.h>
 #include <linux/smp.h>
 #include <linux/kdebug.h>
 #include <linux/export.h>
 #include <linux/pgtable.h>

 #include <asm/delay.h>
 #include <asm/ptrace.h>
 #include <asm/oplib.h>
 #include <asm/page.h>
 #include <asm/unistd.h>
 #include <asm/traps.h>

 #include "entry.h"
 #include "kernel.h"

 /* #define TRAP_DEBUG */

 static void instruction_dump(unsigned long *pc)
 {
 	int i;

 	if((((unsigned long) pc) & 3))
                 return;

 	for(i = -3; i < 6; i++)
 		printk("%c%08lx%c",i?' ':'<',pc[i],i?' ':'>');
 	printk("\n");
 }

 #define __SAVE __asm__ __volatile__("save %sp, -0x40, %sp\n\t")
 #define __RESTORE __asm__ __volatile__("restore %g0, %g0, %g0\n\t")

 void __noreturn die_if_kernel(char *str, struct pt_regs *regs)
 {
 	static int die_counter;
 	int count = 0;

 	/* Amuse the user. */
 	printk(
 "              \\|/ ____ \\|/\n"
 "              \"@'/ ,. \\`@\"\n"
 "              /_| \\__/ |_\\\n"
 "                 \\__U_/\n");

 	printk("%s(%d): %s [#%d]\n", current->comm, task_pid_nr(current), str, ++die_counter);
 	show_regs(regs);
 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);

 	__SAVE; __SAVE; __SAVE; __SAVE;
 	__SAVE; __SAVE; __SAVE; __SAVE;
 	__RESTORE; __RESTORE; __RESTORE; __RESTORE;
 	__RESTORE; __RESTORE; __RESTORE; __RESTORE;

 	{
 		struct reg_window32 *rw = (struct reg_window32 *)regs->u_regs[UREG_FP];

 		/* Stop the back trace when we hit userland or we
 		 * find some badly aligned kernel stack. Set an upper
 		 * bound in case our stack is trashed and we loop.
 		 */
 		while(rw					&&
 		      count++ < 30				&&
                       (((unsigned long) rw) >= PAGE_OFFSET)	&&
 		      !(((unsigned long) rw) & 0x7)) {
 			printk("Caller[%08lx]: %pS\n", rw->ins[7],
 			       (void *) rw->ins[7]);
 			rw = (struct reg_window32 *)rw->ins[6];
 		}
 	}
 	printk("Instruction DUMP:");
 	instruction_dump ((unsigned long *) regs->pc);
 	make_task_dead((regs->psr & PSR_PS) ? SIGKILL : SIGSEGV);
 }

 void do_hw_interrupt(struct pt_regs *regs, unsigned long type)
 {
 	if(type < 0x80) {
 		/* Sun OS's puke from bad traps, Linux survives! */
 		printk("Unimplemented Sparc TRAP, type = %02lx\n", type);
 		die_if_kernel("Whee... Hello Mr. Penguin", regs);
 	}

 	if(regs->psr & PSR_PS)
 		die_if_kernel("Kernel bad trap", regs);

 	force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
 			       (void __user *)regs->pc, type - 0x80);
 }

 void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 			    unsigned long psr)
 {
 	if(psr & PSR_PS)
 		die_if_kernel("Kernel illegal instruction", regs);
 #ifdef TRAP_DEBUG
 	printk("Ill instr. at pc=%08lx instruction is %08lx\n",
 	       regs->pc, *(unsigned long *)regs->pc);
 #endif

 	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, current);
 }

 void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 			 unsigned long psr)
 {
 	if(psr & PSR_PS)
 		die_if_kernel("Penguin instruction from Penguin mode??!?!", regs);
 	send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, current);
 }

 /* XXX User may want to be allowed to do this. XXX */

 void do_memaccess_unaligned(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 			    unsigned long psr)
 {
 	if(regs->psr & PSR_PS) {
 		printk("KERNEL MNA at pc %08lx npc %08lx called by %08lx\n", pc, npc,
 		       regs->u_regs[UREG_RETPC]);
 		die_if_kernel("BOGUS", regs);
 		/* die_if_kernel("Kernel MNA access", regs); */
 	}
 #if 0
 	show_regs (regs);
 	instruction_dump ((unsigned long *) regs->pc);
 	printk ("do_MNA!\n");
 #endif
 	send_sig_fault(SIGBUS, BUS_ADRALN,
 		       /* FIXME: Should dig out mna address */ (void *)0,
 		       current);
 }

 static unsigned long init_fsr = 0x0UL;
 static unsigned long init_fregs[32] __attribute__ ((aligned (8))) =
                 { ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL,
 		  ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL,
 		  ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL,
 		  ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL };

 void do_fpd_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		 unsigned long psr)
 {
 	/* Sanity check... */
 	if(psr & PSR_PS)
 		die_if_kernel("Kernel gets FloatingPenguinUnit disabled trap", regs);

 	put_psr(get_psr() | PSR_EF);    /* Allow FPU ops. */
 	regs->psr |= PSR_EF;
 #ifndef CONFIG_SMP
 	if(last_task_used_math == current)
 		return;
 	if(last_task_used_math) {
 		/* Other processes fpu state, save away */
 		struct task_struct *fptask = last_task_used_math;
 		fpsave(&fptask->thread.float_regs[0], &fptask->thread.fsr,
 		       &fptask->thread.fpqueue[0], &fptask->thread.fpqdepth);
 	}
 	last_task_used_math = current;
 	if(used_math()) {
 		fpload(&current->thread.float_regs[0], &current->thread.fsr);
 	} else {
 		/* Set initial sane state. */
 		fpload(&init_fregs[0], &init_fsr);
 		set_used_math();
 	}
 #else
 	if(!used_math()) {
 		fpload(&init_fregs[0], &init_fsr);
 		set_used_math();
 	} else {
 		fpload(&current->thread.float_regs[0], &current->thread.fsr);
 	}
 	set_thread_flag(TIF_USEDFPU);
 #endif
 }

 static unsigned long fake_regs[32] __attribute__ ((aligned (8)));
 static unsigned long fake_fsr;
 static unsigned long fake_queue[32] __attribute__ ((aligned (8)));
 static unsigned long fake_depth;

 void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		 unsigned long psr)
 {
 	static int calls;
 	unsigned long fsr;
 	int ret = 0;
 	int code;
 #ifndef CONFIG_SMP
 	struct task_struct *fpt = last_task_used_math;
 #else
 	struct task_struct *fpt = current;
 #endif
 	put_psr(get_psr() | PSR_EF);
 	/* If nobody owns the fpu right now, just clear the
 	 * error into our fake static buffer and hope it don't
 	 * happen again.  Thank you crashme...
 	 */
 #ifndef CONFIG_SMP
 	if(!fpt) {
 #else
 	if (!test_tsk_thread_flag(fpt, TIF_USEDFPU)) {
 #endif
 		fpsave(&fake_regs[0], &fake_fsr, &fake_queue[0], &fake_depth);
 		regs->psr &= ~PSR_EF;
 		return;
 	}
 	fpsave(&fpt->thread.float_regs[0], &fpt->thread.fsr,
 	       &fpt->thread.fpqueue[0], &fpt->thread.fpqdepth);
 #ifdef DEBUG_FPU
 	printk("Hmm, FP exception, fsr was %016lx\n", fpt->thread.fsr);
 #endif

 	switch ((fpt->thread.fsr & 0x1c000)) {
 	/* switch on the contents of the ftt [floating point trap type] field */
 #ifdef DEBUG_FPU
 	case (1 << 14):
 		printk("IEEE_754_exception\n");
 		break;
 #endif
 	case (2 << 14):  /* unfinished_FPop (underflow & co) */
 	case (3 << 14):  /* unimplemented_FPop (quad stuff, maybe sqrt) */
 		ret = do_mathemu(regs, fpt);
 		break;
 #ifdef DEBUG_FPU
 	case (4 << 14):
 		printk("sequence_error (OS bug...)\n");
 		break;
 	case (5 << 14):
 		printk("hardware_error (uhoh!)\n");
 		break;
 	case (6 << 14):
 		printk("invalid_fp_register (user error)\n");
 		break;
 #endif /* DEBUG_FPU */
 	}
 	/* If we successfully emulated the FPop, we pretend the trap never happened :-> */
 	if (ret) {
 		fpload(&current->thread.float_regs[0], &current->thread.fsr);
 		return;
 	}
 	/* nope, better SIGFPE the offending process... */

 #ifdef CONFIG_SMP
 	clear_tsk_thread_flag(fpt, TIF_USEDFPU);
 #endif
 	if(psr & PSR_PS) {
 		/* The first fsr store/load we tried trapped,
 		 * the second one will not (we hope).
 		 */
 		printk("WARNING: FPU exception from kernel mode. at pc=%08lx\n",
 		       regs->pc);
 		regs->pc = regs->npc;
 		regs->npc += 4;
 		calls++;
 		if(calls > 2)
 			die_if_kernel("Too many Penguin-FPU traps from kernel mode",
 				      regs);
 		return;
 	}

 	fsr = fpt->thread.fsr;
 	code = FPE_FLTUNK;
 	if ((fsr & 0x1c000) == (1 << 14)) {
 		if (fsr & 0x10)
 			code = FPE_FLTINV;
 		else if (fsr & 0x08)
 			code = FPE_FLTOVF;
 		else if (fsr & 0x04)
 			code = FPE_FLTUND;
 		else if (fsr & 0x02)
 			code = FPE_FLTDIV;
 		else if (fsr & 0x01)
 			code = FPE_FLTRES;
 	}
 	send_sig_fault(SIGFPE, code, (void __user *)pc, fpt);
 #ifndef CONFIG_SMP
 	last_task_used_math = NULL;
 #endif
 	regs->psr &= ~PSR_EF;
 	if(calls > 0)
 		calls=0;
 }

 void handle_tag_overflow(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 			 unsigned long psr)
 {
 	if(psr & PSR_PS)
 		die_if_kernel("Penguin overflow trap from kernel mode", regs);
 	send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, current);
 }

 void handle_watchpoint(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		       unsigned long psr)
 {
 #ifdef TRAP_DEBUG
 	printk("Watchpoint detected at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
 	if(psr & PSR_PS)
 		panic("Tell me what a watchpoint trap is, and I'll then deal "
 		      "with such a beast...");
 }

 void handle_reg_access(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		       unsigned long psr)
 {
 #ifdef TRAP_DEBUG
 	printk("Register Access Exception at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
 	force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc);
 }

 void handle_cp_disabled(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 			unsigned long psr)
 {
 	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
 }

 void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 			 unsigned long psr)
 {
 #ifdef TRAP_DEBUG
 	printk("Co-Processor Exception at PC %08lx NPC %08lx PSR %08lx\n",
 	       pc, npc, psr);
 #endif
 	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
 }

 void handle_hw_divzero(struct pt_regs *regs, unsigned long pc, unsigned long npc,
 		       unsigned long psr)
 {
 	send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, current);
 }

 #ifdef CONFIG_DEBUG_BUGVERBOSE
 void do_BUG(const char *file, int line)
 {
         // bust_spinlocks(1);   XXX Not in our original BUG()
         printk("kernel BUG at %s:%d!\n", file, line);
 }
 EXPORT_SYMBOL(do_BUG);
 #endif

 /* Since we have our mappings set up, on multiprocessors we can spin them
  * up here so that timer interrupts work during initialization.
  */

 void trap_init(void)
 {
 	extern void thread_info_offsets_are_bolixed_pete(void);

 	/* Force linker to barf if mismatched */
 	if (TI_UWINMASK    != offsetof(struct thread_info, uwinmask) ||
 	    TI_TASK        != offsetof(struct thread_info, task) ||
 	    TI_FLAGS       != offsetof(struct thread_info, flags) ||
 	    TI_CPU         != offsetof(struct thread_info, cpu) ||
 	    TI_PREEMPT     != offsetof(struct thread_info, preempt_count) ||
 	    TI_SOFTIRQ     != offsetof(struct thread_info, softirq_count) ||
 	    TI_HARDIRQ     != offsetof(struct thread_info, hardirq_count) ||
 	    TI_KSP         != offsetof(struct thread_info, ksp) ||
 	    TI_KPC         != offsetof(struct thread_info, kpc) ||
 	    TI_KPSR        != offsetof(struct thread_info, kpsr) ||
 	    TI_KWIM        != offsetof(struct thread_info, kwim) ||
 	    TI_REG_WINDOW  != offsetof(struct thread_info, reg_window) ||
 	    TI_RWIN_SPTRS  != offsetof(struct thread_info, rwbuf_stkptrs) ||
 	    TI_W_SAVED     != offsetof(struct thread_info, w_saved))
 		thread_info_offsets_are_bolixed_pete();

 	/* Attach to the address space of init_task. */
 	mmgrab(&init_mm);
 	current->active_mm = &init_mm;

 	/* NOTE: Other cpus have this done as they are started
 	 *       up on SMP.
 	 */
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* arch/sparc/kernel/traps.c
	*
	* Copyright 1995, 2008 David S. Miller (davem@davemloft.net)
	* Copyright 2000 Jakub Jelinek (jakub@redhat.com)
	*/

	/*
	* I hate traps on the sparc, grrr...
	*/

	#include <linux/cpu.h>
	#include <linux/sched/mm.h>
	#include <linux/sched/debug.h>
	#include <linux/mm_types.h>
	#include <linux/kernel.h>
	#include <linux/signal.h>
	#include <linux/smp.h>
	#include <linux/kdebug.h>
	#include <linux/export.h>
	#include <linux/pgtable.h>

	#include <asm/delay.h>
	#include <asm/ptrace.h>
	#include <asm/oplib.h>
	#include <asm/page.h>
	#include <asm/unistd.h>
	#include <asm/traps.h>

	#include "entry.h"
	#include "kernel.h"

	/* #define TRAP_DEBUG */

	static void instruction_dump(unsigned long *pc)
	{
	int i;

	if((((unsigned long) pc) & 3))
	return;

	for(i = -3; i < 6; i++)
	printk("%c%08lx%c",i?' ':'<',pc[i],i?' ':'>');
	printk("\n");
	}

	#define __SAVE __asm__ __volatile__("save %sp, -0x40, %sp\n\t")
	#define __RESTORE __asm__ __volatile__("restore %g0, %g0, %g0\n\t")

	void __noreturn die_if_kernel(char str, struct pt_regs regs)
	{
	static int die_counter;
	int count = 0;

	/* Amuse the user. */
	printk(
	" \\\|/ ____ \\\|/\n"
	" \"@'/ ,. \\`@\"\n"
	" /_\| \\__/ \|_\\\n"
	" \\__U_/\n");

	printk("%s(%d): %s [#%d]\n", current->comm, task_pid_nr(current), str, ++die_counter);
	show_regs(regs);
	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);

	__SAVE; __SAVE; __SAVE; __SAVE;
	__SAVE; __SAVE; __SAVE; __SAVE;
	__RESTORE; __RESTORE; __RESTORE; __RESTORE;
	__RESTORE; __RESTORE; __RESTORE; __RESTORE;

	{
	struct reg_window32 rw = (struct reg_window32 )regs->u_regs[UREG_FP];

	/* Stop the back trace when we hit userland or we
	* find some badly aligned kernel stack. Set an upper
	* bound in case our stack is trashed and we loop.
	*/
	while(rw &&
	count++ < 30 &&
	(((unsigned long) rw) >= PAGE_OFFSET) &&
	!(((unsigned long) rw) & 0x7)) {
	printk("Caller[%08lx]: %pS\n", rw->ins[7],
	(void *) rw->ins[7]);
	rw = (struct reg_window32 *)rw->ins[6];
	}
	}
	printk("Instruction DUMP:");
	instruction_dump ((unsigned long *) regs->pc);
	make_task_dead((regs->psr & PSR_PS) ? SIGKILL : SIGSEGV);
	}

	void do_hw_interrupt(struct pt_regs *regs, unsigned long type)
	{
	if(type < 0x80) {
	/* Sun OS's puke from bad traps, Linux survives! */
	printk("Unimplemented Sparc TRAP, type = %02lx\n", type);
	die_if_kernel("Whee... Hello Mr. Penguin", regs);
	}

	if(regs->psr & PSR_PS)
	die_if_kernel("Kernel bad trap", regs);

	force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
	(void __user *)regs->pc, type - 0x80);
	}

	void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
	unsigned long psr)
	{
	if(psr & PSR_PS)
	die_if_kernel("Kernel illegal instruction", regs);
	#ifdef TRAP_DEBUG
	printk("Ill instr. at pc=%08lx instruction is %08lx\n",
	regs->pc, (unsigned long )regs->pc);
	#endif

	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, current);
	}

	void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
	unsigned long psr)
	{
	if(psr & PSR_PS)
	die_if_kernel("Penguin instruction from Penguin mode??!?!", regs);
	send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, current);
	}

	/* XXX User may want to be allowed to do this. XXX */

	void do_memaccess_unaligned(struct pt_regs *regs, unsigned long pc, unsigned long npc,
	unsigned long psr)
	{
	if(regs->psr & PSR_PS) {
	printk("KERNEL MNA at pc %08lx npc %08lx called by %08lx\n", pc, npc,
	regs->u_regs[UREG_RETPC]);
	die_if_kernel("BOGUS", regs);
	/* die_if_kernel("Kernel MNA access", regs); */
	}
	#if 0
	show_regs (regs);
	instruction_dump ((unsigned long *) regs->pc);
	printk ("do_MNA!\n");
	#endif
	send_sig_fault(SIGBUS, BUS_ADRALN,
	/* FIXME: Should dig out mna address / (void )0,
	current);
	}

	static unsigned long init_fsr = 0x0UL;
	static unsigned long init_fregs[32] __attribute__ ((aligned (8))) =
	{ ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL,
	~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL,
	~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL,
	~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL };

	void do_fpd_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
	unsigned long psr)
	{
	/* Sanity check... */
	if(psr & PSR_PS)
	die_if_kernel("Kernel gets FloatingPenguinUnit disabled trap", regs);

	put_psr(get_psr() \| PSR_EF); /* Allow FPU ops. */
	regs->psr \|= PSR_EF;
	#ifndef CONFIG_SMP
	if(last_task_used_math == current)
	return;
	if(last_task_used_math) {
	/* Other processes fpu state, save away */
	struct task_struct *fptask = last_task_used_math;
	fpsave(&fptask->thread.float_regs[0], &fptask->thread.fsr,
	&fptask->thread.fpqueue[0], &fptask->thread.fpqdepth);
	}
	last_task_used_math = current;
	if(used_math()) {
	fpload(&current->thread.float_regs[0], &current->thread.fsr);
	} else {
	/* Set initial sane state. */
	fpload(&init_fregs[0], &init_fsr);
	set_used_math();
	}
	#else
	if(!used_math()) {
	fpload(&init_fregs[0], &init_fsr);
	set_used_math();
	} else {
	fpload(&current->thread.float_regs[0], &current->thread.fsr);
	}
	set_thread_flag(TIF_USEDFPU);
	#endif
	}

	static unsigned long fake_regs[32] __attribute__ ((aligned (8)));
	static unsigned long fake_fsr;
	static unsigned long fake_queue[32] __attribute__ ((aligned (8)));
	static unsigned long fake_depth;

	void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
	unsigned long psr)
	{
	static int calls;
	unsigned long fsr;
	int ret = 0;
	int code;
	#ifndef CONFIG_SMP
	struct task_struct *fpt = last_task_used_math;
	#else
	struct task_struct *fpt = current;
	#endif
	put_psr(get_psr() \| PSR_EF);
	/* If nobody owns the fpu right now, just clear the
	* error into our fake static buffer and hope it don't
	* happen again. Thank you crashme...
	*/
	#ifndef CONFIG_SMP
	if(!fpt) {
	#else
	if (!test_tsk_thread_flag(fpt, TIF_USEDFPU)) {
	#endif
	fpsave(&fake_regs[0], &fake_fsr, &fake_queue[0], &fake_depth);
	regs->psr &= ~PSR_EF;
	return;
	}
	fpsave(&fpt->thread.float_regs[0], &fpt->thread.fsr,
	&fpt->thread.fpqueue[0], &fpt->thread.fpqdepth);
	#ifdef DEBUG_FPU
	printk("Hmm, FP exception, fsr was %016lx\n", fpt->thread.fsr);
	#endif

	switch ((fpt->thread.fsr & 0x1c000)) {
	/* switch on the contents of the ftt [floating point trap type] field */
	#ifdef DEBUG_FPU
	case (1 << 14):
	printk("IEEE_754_exception\n");
	break;
	#endif
	case (2 << 14): /* unfinished_FPop (underflow & co) */
	case (3 << 14): /* unimplemented_FPop (quad stuff, maybe sqrt) */
	ret = do_mathemu(regs, fpt);
	break;
	#ifdef DEBUG_FPU
	case (4 << 14):
	printk("sequence_error (OS bug...)\n");
	break;
	case (5 << 14):
	printk("hardware_error (uhoh!)\n");
	break;
	case (6 << 14):
	printk("invalid_fp_register (user error)\n");
	break;
	#endif /* DEBUG_FPU */
	}
	/* If we successfully emulated the FPop, we pretend the trap never happened :-> */
	if (ret) {
	fpload(&current->thread.float_regs[0], &current->thread.fsr);
	return;
	}
	/* nope, better SIGFPE the offending process... */

	#ifdef CONFIG_SMP
	clear_tsk_thread_flag(fpt, TIF_USEDFPU);
	#endif
	if(psr & PSR_PS) {
	/* The first fsr store/load we tried trapped,
	* the second one will not (we hope).
	*/
	printk("WARNING: FPU exception from kernel mode. at pc=%08lx\n",
	regs->pc);
	regs->pc = regs->npc;
	regs->npc += 4;
	calls++;
	if(calls > 2)
	die_if_kernel("Too many Penguin-FPU traps from kernel mode",
	regs);
	return;
	}

	fsr = fpt->thread.fsr;
	code = FPE_FLTUNK;
	if ((fsr & 0x1c000) == (1 << 14)) {
	if (fsr & 0x10)
	code = FPE_FLTINV;
	else if (fsr & 0x08)
	code = FPE_FLTOVF;
	else if (fsr & 0x04)
	code = FPE_FLTUND;
	else if (fsr & 0x02)
	code = FPE_FLTDIV;
	else if (fsr & 0x01)
	code = FPE_FLTRES;
	}
	send_sig_fault(SIGFPE, code, (void __user *)pc, fpt);
	#ifndef CONFIG_SMP
	last_task_used_math = NULL;
	#endif
	regs->psr &= ~PSR_EF;
	if(calls > 0)
	calls=0;
	}

	void handle_tag_overflow(struct pt_regs *regs, unsigned long pc, unsigned long npc,
	unsigned long psr)
	{
	if(psr & PSR_PS)
	die_if_kernel("Penguin overflow trap from kernel mode", regs);
	send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, current);
	}

	void handle_watchpoint(struct pt_regs *regs, unsigned long pc, unsigned long npc,
	unsigned long psr)
	{
	#ifdef TRAP_DEBUG
	printk("Watchpoint detected at PC %08lx NPC %08lx PSR %08lx\n",
	pc, npc, psr);
	#endif
	if(psr & PSR_PS)
	panic("Tell me what a watchpoint trap is, and I'll then deal "
	"with such a beast...");
	}

	void handle_reg_access(struct pt_regs *regs, unsigned long pc, unsigned long npc,
	unsigned long psr)
	{
	#ifdef TRAP_DEBUG
	printk("Register Access Exception at PC %08lx NPC %08lx PSR %08lx\n",
	pc, npc, psr);
	#endif
	force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc);
	}

	void handle_cp_disabled(struct pt_regs *regs, unsigned long pc, unsigned long npc,
	unsigned long psr)
	{
	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
	}

	void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long npc,
	unsigned long psr)
	{
	#ifdef TRAP_DEBUG
	printk("Co-Processor Exception at PC %08lx NPC %08lx PSR %08lx\n",
	pc, npc, psr);
	#endif
	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
	}

	void handle_hw_divzero(struct pt_regs *regs, unsigned long pc, unsigned long npc,
	unsigned long psr)
	{
	send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, current);
	}

	#ifdef CONFIG_DEBUG_BUGVERBOSE
	void do_BUG(const char *file, int line)
	{
	// bust_spinlocks(1); XXX Not in our original BUG()
	printk("kernel BUG at %s:%d!\n", file, line);
	}
	EXPORT_SYMBOL(do_BUG);
	#endif

	/* Since we have our mappings set up, on multiprocessors we can spin them
	* up here so that timer interrupts work during initialization.
	*/

	void trap_init(void)
	{
	extern void thread_info_offsets_are_bolixed_pete(void);

	/* Force linker to barf if mismatched */
	if (TI_UWINMASK != offsetof(struct thread_info, uwinmask) \|\|
	TI_TASK != offsetof(struct thread_info, task) \|\|
	TI_FLAGS != offsetof(struct thread_info, flags) \|\|
	TI_CPU != offsetof(struct thread_info, cpu) \|\|
	TI_PREEMPT != offsetof(struct thread_info, preempt_count) \|\|
	TI_SOFTIRQ != offsetof(struct thread_info, softirq_count) \|\|
	TI_HARDIRQ != offsetof(struct thread_info, hardirq_count) \|\|
	TI_KSP != offsetof(struct thread_info, ksp) \|\|
	TI_KPC != offsetof(struct thread_info, kpc) \|\|
	TI_KPSR != offsetof(struct thread_info, kpsr) \|\|
	TI_KWIM != offsetof(struct thread_info, kwim) \|\|
	TI_REG_WINDOW != offsetof(struct thread_info, reg_window) \|\|
	TI_RWIN_SPTRS != offsetof(struct thread_info, rwbuf_stkptrs) \|\|
	TI_W_SAVED != offsetof(struct thread_info, w_saved))
	thread_info_offsets_are_bolixed_pete();

	/* Attach to the address space of init_task. */
	mmgrab(&init_mm);
	current->active_mm = &init_mm;

	/* NOTE: Other cpus have this done as they are started
	* up on SMP.
	*/
	}