arch/sparc/mm/fault.c - third_party/linux - Git at Google

 /* $Id: fault.c,v 1.122 2001/11/17 07:19:26 davem Exp $
  * fault.c:  Page fault handlers for the Sparc.
  *
  * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
  * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
  * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
  */

 #include <asm/head.h>

 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/sched.h>
 #include <linux/ptrace.h>
 #include <linux/mman.h>
 #include <linux/threads.h>
 #include <linux/kernel.h>
 #include <linux/signal.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
 #include <linux/smp_lock.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>

 #include <asm/system.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/memreg.h>
 #include <asm/openprom.h>
 #include <asm/oplib.h>
 #include <asm/smp.h>
 #include <asm/traps.h>
 #include <asm/kdebug.h>
 #include <asm/uaccess.h>

 extern int prom_node_root;

 /* At boot time we determine these two values necessary for setting
  * up the segment maps and page table entries (pte's).
  */

 int num_segmaps, num_contexts;
 int invalid_segment;

 /* various Virtual Address Cache parameters we find at boot time... */

 int vac_size, vac_linesize, vac_do_hw_vac_flushes;
 int vac_entries_per_context, vac_entries_per_segment;
 int vac_entries_per_page;

 /* Nice, simple, prom library does all the sweating for us. ;) */
 int prom_probe_memory (void)
 {
 	register struct linux_mlist_v0 *mlist;
 	register unsigned long bytes, base_paddr, tally;
 	register int i;

 	i = 0;
 	mlist= *prom_meminfo()->v0_available;
 	bytes = tally = mlist->num_bytes;
 	base_paddr = (unsigned long) mlist->start_adr;

 	sp_banks[0].base_addr = base_paddr;
 	sp_banks[0].num_bytes = bytes;

 	while (mlist->theres_more != (void *) 0){
 		i++;
 		mlist = mlist->theres_more;
 		bytes = mlist->num_bytes;
 		tally += bytes;
 		if (i > SPARC_PHYS_BANKS-1) {
 			printk ("The machine has more banks than "
 				"this kernel can support\n"
 				"Increase the SPARC_PHYS_BANKS "
 				"setting (currently %d)\n",
 				SPARC_PHYS_BANKS);
 			i = SPARC_PHYS_BANKS-1;
 			break;
 		}

 		sp_banks[i].base_addr = (unsigned long) mlist->start_adr;
 		sp_banks[i].num_bytes = mlist->num_bytes;
 	}

 	i++;
 	sp_banks[i].base_addr = 0xdeadbeef;
 	sp_banks[i].num_bytes = 0;

 	/* Now mask all bank sizes on a page boundary, it is all we can
 	 * use anyways.
 	 */
 	for(i=0; sp_banks[i].num_bytes != 0; i++)
 		sp_banks[i].num_bytes &= PAGE_MASK;

 	return tally;
 }

 /* Traverse the memory lists in the prom to see how much physical we
  * have.
  */
 unsigned long
 probe_memory(void)
 {
 	int total;

 	total = prom_probe_memory();

 	/* Oh man, much nicer, keep the dirt in promlib. */
 	return total;
 }

 extern void sun4c_complete_all_stores(void);

 /* Whee, a level 15 NMI interrupt memory error.  Let's have fun... */
 asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,
 				unsigned long svaddr, unsigned long aerr,
 				unsigned long avaddr)
 {
 	sun4c_complete_all_stores();
 	printk("FAULT: NMI received\n");
 	printk("SREGS: Synchronous Error %08lx\n", serr);
 	printk("       Synchronous Vaddr %08lx\n", svaddr);
 	printk("      Asynchronous Error %08lx\n", aerr);
 	printk("      Asynchronous Vaddr %08lx\n", avaddr);
 	if (sun4c_memerr_reg)
 		printk("     Memory Parity Error %08lx\n", *sun4c_memerr_reg);
 	printk("REGISTER DUMP:\n");
 	show_regs(regs);
 	prom_halt();
 }

 static void unhandled_fault(unsigned long, struct task_struct *,
 		struct pt_regs *) __attribute__ ((noreturn));

 static void unhandled_fault(unsigned long address, struct task_struct *tsk,
                      struct pt_regs *regs)
 {
 	if((unsigned long) address < PAGE_SIZE) {
 		printk(KERN_ALERT
 		    "Unable to handle kernel NULL pointer dereference\n");
 	} else {
 		printk(KERN_ALERT "Unable to handle kernel paging request "
 		       "at virtual address %08lx\n", address);
 	}
 	printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
 		(tsk->mm ? tsk->mm->context : tsk->active_mm->context));
 	printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
 		(tsk->mm ? (unsigned long) tsk->mm->pgd :
 		 	(unsigned long) tsk->active_mm->pgd));
 	die_if_kernel("Oops", regs);
 }

 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
 			    unsigned long address)
 {
 	struct pt_regs regs;
 	unsigned long g2;
 	unsigned int insn;
 	int i;

 	i = search_extables_range(ret_pc, &g2);
 	switch (i) {
 	case 3:
 		/* load & store will be handled by fixup */
 		return 3;

 	case 1:
 		/* store will be handled by fixup, load will bump out */
 		/* for _to_ macros */
 		insn = *((unsigned int *) pc);
 		if ((insn >> 21) & 1)
 			return 1;
 		break;

 	case 2:
 		/* load will be handled by fixup, store will bump out */
 		/* for _from_ macros */
 		insn = *((unsigned int *) pc);
 		if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
 			return 2;
 		break;

 	default:
 		break;
 	};

 	memset(&regs, 0, sizeof (regs));
 	regs.pc = pc;
 	regs.npc = pc + 4;
 	__asm__ __volatile__(
 		"rd %%psr, %0\n\t"
 		"nop\n\t"
 		"nop\n\t"
 		"nop\n" : "=r" (regs.psr));
 	unhandled_fault(address, current, &regs);

 	/* Not reached */
 	return 0;
 }

 extern unsigned long safe_compute_effective_address(struct pt_regs *,
 						    unsigned int);

 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 {
 	unsigned int insn;

 	if (text_fault)
 		return regs->pc;

 	if (regs->psr & PSR_PS) {
 		insn = *(unsigned int *) regs->pc;
 	} else {
 		__get_user(insn, (unsigned int *) regs->pc);
 	}

 	return safe_compute_effective_address(regs, insn);
 }

 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 			       unsigned long address)
 {
 	struct vm_area_struct *vma;
 	struct task_struct *tsk = current;
 	struct mm_struct *mm = tsk->mm;
 	unsigned int fixup;
 	unsigned long g2;
 	siginfo_t info;
 	int from_user = !(regs->psr & PSR_PS);

 	if(text_fault)
 		address = regs->pc;

 	/*
 	 * We fault-in kernel-space virtual memory on-demand. The
 	 * 'reference' page table is init_mm.pgd.
 	 *
 	 * NOTE! We MUST NOT take any locks for this case. We may
 	 * be in an interrupt or a critical region, and should
 	 * only copy the information from the master page table,
 	 * nothing more.
 	 */
 	if (!ARCH_SUN4C_SUN4 && address >= TASK_SIZE)
 		goto vmalloc_fault;

 	info.si_code = SEGV_MAPERR;

 	/*
 	 * If we're in an interrupt or have no user
 	 * context, we must not take the fault..
 	 */
         if (in_atomic() || !mm)
                 goto no_context;

 	down_read(&mm->mmap_sem);

 	/*
 	 * The kernel referencing a bad kernel pointer can lock up
 	 * a sun4c machine completely, so we must attempt recovery.
 	 */
 	if(!from_user && address >= PAGE_OFFSET)
 		goto bad_area;

 	vma = find_vma(mm, address);
 	if(!vma)
 		goto bad_area;
 	if(vma->vm_start <= address)
 		goto good_area;
 	if(!(vma->vm_flags & VM_GROWSDOWN))
 		goto bad_area;
 	if(expand_stack(vma, address))
 		goto bad_area;
 	/*
 	 * Ok, we have a good vm_area for this memory access, so
 	 * we can handle it..
 	 */
 good_area:
 	info.si_code = SEGV_ACCERR;
 	if(write) {
 		if(!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
 	} else {
 		/* Allow reads even for write-only mappings */
 		if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 			goto bad_area;
 	}

 	/*
 	 * If for any reason at all we couldn't handle the fault,
 	 * make sure we exit gracefully rather than endlessly redo
 	 * the fault.
 	 */
 	switch (handle_mm_fault(mm, vma, address, write)) {
 	case VM_FAULT_SIGBUS:
 		goto do_sigbus;
 	case VM_FAULT_OOM:
 		goto out_of_memory;
 	case VM_FAULT_MAJOR:
 		current->maj_flt++;
 		break;
 	case VM_FAULT_MINOR:
 	default:
 		current->min_flt++;
 		break;
 	}
 	up_read(&mm->mmap_sem);
 	return;

 	/*
 	 * Something tried to access memory that isn't in our memory map..
 	 * Fix it, but check if it's kernel or user first..
 	 */
 bad_area:
 	up_read(&mm->mmap_sem);

 bad_area_nosemaphore:
 	/* User mode accesses just cause a SIGSEGV */
 	if(from_user) {
 #if 0
 		printk("Fault whee %s [%d]: segfaults at %08lx pc=%08lx\n",
 		       tsk->comm, tsk->pid, address, regs->pc);
 #endif
 		info.si_signo = SIGSEGV;
 		info.si_errno = 0;
 		/* info.si_code set above to make clear whether
 		   this was a SEGV_MAPERR or SEGV_ACCERR fault.  */
 		info.si_addr = (void __user *)compute_si_addr(regs, text_fault);
 		info.si_trapno = 0;
 		force_sig_info (SIGSEGV, &info, tsk);
 		return;
 	}

 	/* Is this in ex_table? */
 no_context:
 	g2 = regs->u_regs[UREG_G2];
 	if (!from_user && (fixup = search_extables_range(regs->pc, &g2))) {
 		if (fixup > 10) { /* Values below are reserved for other things */
 			extern const unsigned __memset_start[];
 			extern const unsigned __memset_end[];
 			extern const unsigned __csum_partial_copy_start[];
 			extern const unsigned __csum_partial_copy_end[];

 #ifdef DEBUG_EXCEPTIONS
 			printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
 			printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 				regs->pc, fixup, g2);
 #endif
 			if ((regs->pc >= (unsigned long)__memset_start &&
 			     regs->pc < (unsigned long)__memset_end) ||
 			    (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 			     regs->pc < (unsigned long)__csum_partial_copy_end)) {
 			        regs->u_regs[UREG_I4] = address;
 				regs->u_regs[UREG_I5] = regs->pc;
 			}
 			regs->u_regs[UREG_G2] = g2;
 			regs->pc = fixup;
 			regs->npc = regs->pc + 4;
 			return;
 		}
 	}

 	unhandled_fault (address, tsk, regs);
 	do_exit(SIGKILL);

 /*
  * We ran out of memory, or some other thing happened to us that made
  * us unable to handle the page fault gracefully.
  */
 out_of_memory:
 	up_read(&mm->mmap_sem);
 	printk("VM: killing process %s\n", tsk->comm);
 	if (from_user)
 		do_exit(SIGKILL);
 	goto no_context;

 do_sigbus:
 	up_read(&mm->mmap_sem);
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;
 	info.si_code = BUS_ADRERR;
 	info.si_addr = (void __user *) compute_si_addr(regs, text_fault);
 	info.si_trapno = 0;
 	force_sig_info (SIGBUS, &info, tsk);
 	if (!from_user)
 		goto no_context;

 vmalloc_fault:
 	{
 		/*
 		 * Synchronize this task's top level page-table
 		 * with the 'reference' page table.
 		 */
 		int offset = pgd_index(address);
 		pgd_t *pgd, *pgd_k;
 		pmd_t *pmd, *pmd_k;

 		pgd = tsk->active_mm->pgd + offset;
 		pgd_k = init_mm.pgd + offset;

 		if (!pgd_present(*pgd)) {
 			if (!pgd_present(*pgd_k))
 				goto bad_area_nosemaphore;
 			pgd_val(*pgd) = pgd_val(*pgd_k);
 			return;
 		}

 		pmd = pmd_offset(pgd, address);
 		pmd_k = pmd_offset(pgd_k, address);

 		if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 			goto bad_area_nosemaphore;
 		*pmd = *pmd_k;
 		return;
 	}
 }

 asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
 			       unsigned long address)
 {
 	extern void sun4c_update_mmu_cache(struct vm_area_struct *,
 					   unsigned long,pte_t);
 	extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long);
 	struct task_struct *tsk = current;
 	struct mm_struct *mm = tsk->mm;
 	pgd_t *pgdp;
 	pte_t *ptep;

 	if (text_fault) {
 		address = regs->pc;
 	} else if (!write &&
 		   !(regs->psr & PSR_PS)) {
 		unsigned int insn, __user *ip;

 		ip = (unsigned int __user *)regs->pc;
 		if (!get_user(insn, ip)) {
 			if ((insn & 0xc1680000) == 0xc0680000)
 				write = 1;
 		}
 	}

 	if (!mm) {
 		/* We are oopsing. */
 		do_sparc_fault(regs, text_fault, write, address);
 		BUG();	/* P3 Oops already, you bitch */
 	}

 	pgdp = pgd_offset(mm, address);
 	ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address);

 	if (pgd_val(*pgdp)) {
 	    if (write) {
 		if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))
 				   == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {
 			unsigned long flags;

 			*ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 				      _SUN4C_PAGE_MODIFIED |
 				      _SUN4C_PAGE_VALID |
 				      _SUN4C_PAGE_DIRTY);

 			local_irq_save(flags);
 			if (sun4c_get_segmap(address) != invalid_segment) {
 				sun4c_put_pte(address, pte_val(*ptep));
 				local_irq_restore(flags);
 				return;
 			}
 			local_irq_restore(flags);
 		}
 	    } else {
 		if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))
 				   == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {
 			unsigned long flags;

 			*ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 				      _SUN4C_PAGE_VALID);

 			local_irq_save(flags);
 			if (sun4c_get_segmap(address) != invalid_segment) {
 				sun4c_put_pte(address, pte_val(*ptep));
 				local_irq_restore(flags);
 				return;
 			}
 			local_irq_restore(flags);
 		}
 	    }
 	}

 	/* This conditional is 'interesting'. */
 	if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))
 	    && (pte_val(*ptep) & _SUN4C_PAGE_VALID))
 		/* Note: It is safe to not grab the MMAP semaphore here because
 		 *       we know that update_mmu_cache() will not sleep for
 		 *       any reason (at least not in the current implementation)
 		 *       and therefore there is no danger of another thread getting
 		 *       on the CPU and doing a shrink_mmap() on this vma.
 		 */
 		sun4c_update_mmu_cache (find_vma(current->mm, address), address,
 					*ptep);
 	else
 		do_sparc_fault(regs, text_fault, write, address);
 }

 /* This always deals with user addresses. */
 inline void force_user_fault(unsigned long address, int write)
 {
 	struct vm_area_struct *vma;
 	struct task_struct *tsk = current;
 	struct mm_struct *mm = tsk->mm;
 	siginfo_t info;

 	info.si_code = SEGV_MAPERR;

 #if 0
 	printk("wf<pid=%d,wr=%d,addr=%08lx>\n",
 	       tsk->pid, write, address);
 #endif
 	down_read(&mm->mmap_sem);
 	vma = find_vma(mm, address);
 	if(!vma)
 		goto bad_area;
 	if(vma->vm_start <= address)
 		goto good_area;
 	if(!(vma->vm_flags & VM_GROWSDOWN))
 		goto bad_area;
 	if(expand_stack(vma, address))
 		goto bad_area;
 good_area:
 	info.si_code = SEGV_ACCERR;
 	if(write) {
 		if(!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
 	} else {
 		if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 			goto bad_area;
 	}
 	switch (handle_mm_fault(mm, vma, address, write)) {
 	case VM_FAULT_SIGBUS:
 	case VM_FAULT_OOM:
 		goto do_sigbus;
 	}
 	up_read(&mm->mmap_sem);
 	return;
 bad_area:
 	up_read(&mm->mmap_sem);
 #if 0
 	printk("Window whee %s [%d]: segfaults at %08lx\n",
 	       tsk->comm, tsk->pid, address);
 #endif
 	info.si_signo = SIGSEGV;
 	info.si_errno = 0;
 	/* info.si_code set above to make clear whether
 	   this was a SEGV_MAPERR or SEGV_ACCERR fault.  */
 	info.si_addr = (void __user *) address;
 	info.si_trapno = 0;
 	force_sig_info (SIGSEGV, &info, tsk);
 	return;

 do_sigbus:
 	up_read(&mm->mmap_sem);
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;
 	info.si_code = BUS_ADRERR;
 	info.si_addr = (void __user *) address;
 	info.si_trapno = 0;
 	force_sig_info (SIGBUS, &info, tsk);
 }

 void window_overflow_fault(void)
 {
 	unsigned long sp;

 	sp = current_thread_info()->rwbuf_stkptrs[0];
 	if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 		force_user_fault(sp + 0x38, 1);
 	force_user_fault(sp, 1);
 }

 void window_underflow_fault(unsigned long sp)
 {
 	if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 		force_user_fault(sp + 0x38, 0);
 	force_user_fault(sp, 0);
 }

 void window_ret_fault(struct pt_regs *regs)
 {
 	unsigned long sp;

 	sp = regs->u_regs[UREG_FP];
 	if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 		force_user_fault(sp + 0x38, 0);
 	force_user_fault(sp, 0);
 }
	/* $Id: fault.c,v 1.122 2001/11/17 07:19:26 davem Exp $
	* fault.c: Page fault handlers for the Sparc.
	*
	* Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
	* Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
	* Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
	*/

	#include <asm/head.h>

	#include <linux/string.h>
	#include <linux/types.h>
	#include <linux/sched.h>
	#include <linux/ptrace.h>
	#include <linux/mman.h>
	#include <linux/threads.h>
	#include <linux/kernel.h>
	#include <linux/signal.h>
	#include <linux/mm.h>
	#include <linux/smp.h>
	#include <linux/smp_lock.h>
	#include <linux/interrupt.h>
	#include <linux/module.h>

	#include <asm/system.h>
	#include <asm/page.h>
	#include <asm/pgtable.h>
	#include <asm/memreg.h>
	#include <asm/openprom.h>
	#include <asm/oplib.h>
	#include <asm/smp.h>
	#include <asm/traps.h>
	#include <asm/kdebug.h>
	#include <asm/uaccess.h>

	extern int prom_node_root;

	/* At boot time we determine these two values necessary for setting
	* up the segment maps and page table entries (pte's).
	*/

	int num_segmaps, num_contexts;
	int invalid_segment;

	/* various Virtual Address Cache parameters we find at boot time... */

	int vac_size, vac_linesize, vac_do_hw_vac_flushes;
	int vac_entries_per_context, vac_entries_per_segment;
	int vac_entries_per_page;

	/* Nice, simple, prom library does all the sweating for us. ;) */
	int prom_probe_memory (void)
	{
	register struct linux_mlist_v0 *mlist;
	register unsigned long bytes, base_paddr, tally;
	register int i;

	i = 0;
	mlist= *prom_meminfo()->v0_available;
	bytes = tally = mlist->num_bytes;
	base_paddr = (unsigned long) mlist->start_adr;

	sp_banks[0].base_addr = base_paddr;
	sp_banks[0].num_bytes = bytes;

	while (mlist->theres_more != (void *) 0){
	i++;
	mlist = mlist->theres_more;
	bytes = mlist->num_bytes;
	tally += bytes;
	if (i > SPARC_PHYS_BANKS-1) {
	printk ("The machine has more banks than "
	"this kernel can support\n"
	"Increase the SPARC_PHYS_BANKS "
	"setting (currently %d)\n",
	SPARC_PHYS_BANKS);
	i = SPARC_PHYS_BANKS-1;
	break;
	}

	sp_banks[i].base_addr = (unsigned long) mlist->start_adr;
	sp_banks[i].num_bytes = mlist->num_bytes;
	}

	i++;
	sp_banks[i].base_addr = 0xdeadbeef;
	sp_banks[i].num_bytes = 0;

	/* Now mask all bank sizes on a page boundary, it is all we can
	* use anyways.
	*/
	for(i=0; sp_banks[i].num_bytes != 0; i++)
	sp_banks[i].num_bytes &= PAGE_MASK;

	return tally;
	}

	/* Traverse the memory lists in the prom to see how much physical we
	* have.
	*/
	unsigned long
	probe_memory(void)
	{
	int total;

	total = prom_probe_memory();

	/* Oh man, much nicer, keep the dirt in promlib. */
	return total;
	}

	extern void sun4c_complete_all_stores(void);

	/* Whee, a level 15 NMI interrupt memory error. Let's have fun... */
	asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,
	unsigned long svaddr, unsigned long aerr,
	unsigned long avaddr)
	{
	sun4c_complete_all_stores();
	printk("FAULT: NMI received\n");
	printk("SREGS: Synchronous Error %08lx\n", serr);
	printk(" Synchronous Vaddr %08lx\n", svaddr);
	printk(" Asynchronous Error %08lx\n", aerr);
	printk(" Asynchronous Vaddr %08lx\n", avaddr);
	if (sun4c_memerr_reg)
	printk(" Memory Parity Error %08lx\n", *sun4c_memerr_reg);
	printk("REGISTER DUMP:\n");
	show_regs(regs);
	prom_halt();
	}

	static void unhandled_fault(unsigned long, struct task_struct *,
	struct pt_regs *) __attribute__ ((noreturn));

	static void unhandled_fault(unsigned long address, struct task_struct *tsk,
	struct pt_regs *regs)
	{
	if((unsigned long) address < PAGE_SIZE) {
	printk(KERN_ALERT
	"Unable to handle kernel NULL pointer dereference\n");
	} else {
	printk(KERN_ALERT "Unable to handle kernel paging request "
	"at virtual address %08lx\n", address);
	}
	printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
	(tsk->mm ? tsk->mm->context : tsk->active_mm->context));
	printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
	(tsk->mm ? (unsigned long) tsk->mm->pgd :
	(unsigned long) tsk->active_mm->pgd));
	die_if_kernel("Oops", regs);
	}

	asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
	unsigned long address)
	{
	struct pt_regs regs;
	unsigned long g2;
	unsigned int insn;
	int i;

	i = search_extables_range(ret_pc, &g2);
	switch (i) {
	case 3:
	/* load & store will be handled by fixup */
	return 3;

	case 1:
	/* store will be handled by fixup, load will bump out */
	/* for _to_ macros */
	insn = ((unsigned int ) pc);
	if ((insn >> 21) & 1)
	return 1;
	break;

	case 2:
	/* load will be handled by fixup, store will bump out */
	/* for _from_ macros */
	insn = ((unsigned int ) pc);
	if (!((insn >> 21) & 1) \|\| ((insn>>19)&0x3f) == 15)
	return 2;
	break;

	default:
	break;
	};

	memset(&regs, 0, sizeof (regs));
	regs.pc = pc;
	regs.npc = pc + 4;
	__asm__ __volatile__(
	"rd %%psr, %0\n\t"
	"nop\n\t"
	"nop\n\t"
	"nop\n" : "=r" (regs.psr));
	unhandled_fault(address, current, &regs);

	/* Not reached */
	return 0;
	}

	extern unsigned long safe_compute_effective_address(struct pt_regs *,
	unsigned int);

	static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
	{
	unsigned int insn;

	if (text_fault)
	return regs->pc;

	if (regs->psr & PSR_PS) {
	insn = (unsigned int ) regs->pc;
	} else {
	__get_user(insn, (unsigned int *) regs->pc);
	}

	return safe_compute_effective_address(regs, insn);
	}

	asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
	unsigned long address)
	{
	struct vm_area_struct *vma;
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	unsigned int fixup;
	unsigned long g2;
	siginfo_t info;
	int from_user = !(regs->psr & PSR_PS);

	if(text_fault)
	address = regs->pc;

	/*
	* We fault-in kernel-space virtual memory on-demand. The
	* 'reference' page table is init_mm.pgd.
	*
	* NOTE! We MUST NOT take any locks for this case. We may
	* be in an interrupt or a critical region, and should
	* only copy the information from the master page table,
	* nothing more.
	*/
	if (!ARCH_SUN4C_SUN4 && address >= TASK_SIZE)
	goto vmalloc_fault;

	info.si_code = SEGV_MAPERR;

	/*
	* If we're in an interrupt or have no user
	* context, we must not take the fault..
	*/
	if (in_atomic() \|\| !mm)
	goto no_context;

	down_read(&mm->mmap_sem);

	/*
	* The kernel referencing a bad kernel pointer can lock up
	* a sun4c machine completely, so we must attempt recovery.
	*/
	if(!from_user && address >= PAGE_OFFSET)
	goto bad_area;

	vma = find_vma(mm, address);
	if(!vma)
	goto bad_area;
	if(vma->vm_start <= address)
	goto good_area;
	if(!(vma->vm_flags & VM_GROWSDOWN))
	goto bad_area;
	if(expand_stack(vma, address))
	goto bad_area;
	/*
	* Ok, we have a good vm_area for this memory access, so
	* we can handle it..
	*/
	good_area:
	info.si_code = SEGV_ACCERR;
	if(write) {
	if(!(vma->vm_flags & VM_WRITE))
	goto bad_area;
	} else {
	/* Allow reads even for write-only mappings */
	if(!(vma->vm_flags & (VM_READ \| VM_EXEC)))
	goto bad_area;
	}

	/*
	* If for any reason at all we couldn't handle the fault,
	* make sure we exit gracefully rather than endlessly redo
	* the fault.
	*/
	switch (handle_mm_fault(mm, vma, address, write)) {
	case VM_FAULT_SIGBUS:
	goto do_sigbus;
	case VM_FAULT_OOM:
	goto out_of_memory;
	case VM_FAULT_MAJOR:
	current->maj_flt++;
	break;
	case VM_FAULT_MINOR:
	default:
	current->min_flt++;
	break;
	}
	up_read(&mm->mmap_sem);
	return;

	/*
	* Something tried to access memory that isn't in our memory map..
	* Fix it, but check if it's kernel or user first..
	*/
	bad_area:
	up_read(&mm->mmap_sem);

	bad_area_nosemaphore:
	/* User mode accesses just cause a SIGSEGV */
	if(from_user) {
	#if 0
	printk("Fault whee %s [%d]: segfaults at %08lx pc=%08lx\n",
	tsk->comm, tsk->pid, address, regs->pc);
	#endif
	info.si_signo = SIGSEGV;
	info.si_errno = 0;
	/* info.si_code set above to make clear whether
	this was a SEGV_MAPERR or SEGV_ACCERR fault. */
	info.si_addr = (void __user *)compute_si_addr(regs, text_fault);
	info.si_trapno = 0;
	force_sig_info (SIGSEGV, &info, tsk);
	return;
	}

	/* Is this in ex_table? */
	no_context:
	g2 = regs->u_regs[UREG_G2];
	if (!from_user && (fixup = search_extables_range(regs->pc, &g2))) {
	if (fixup > 10) { /* Values below are reserved for other things */
	extern const unsigned __memset_start[];
	extern const unsigned __memset_end[];
	extern const unsigned __csum_partial_copy_start[];
	extern const unsigned __csum_partial_copy_end[];

	#ifdef DEBUG_EXCEPTIONS
	printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
	printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
	regs->pc, fixup, g2);
	#endif
	if ((regs->pc >= (unsigned long)__memset_start &&
	regs->pc < (unsigned long)__memset_end) \|\|
	(regs->pc >= (unsigned long)__csum_partial_copy_start &&
	regs->pc < (unsigned long)__csum_partial_copy_end)) {
	regs->u_regs[UREG_I4] = address;
	regs->u_regs[UREG_I5] = regs->pc;
	}
	regs->u_regs[UREG_G2] = g2;
	regs->pc = fixup;
	regs->npc = regs->pc + 4;
	return;
	}
	}

	unhandled_fault (address, tsk, regs);
	do_exit(SIGKILL);

	/*
	* We ran out of memory, or some other thing happened to us that made
	* us unable to handle the page fault gracefully.
	*/
	out_of_memory:
	up_read(&mm->mmap_sem);
	printk("VM: killing process %s\n", tsk->comm);
	if (from_user)
	do_exit(SIGKILL);
	goto no_context;

	do_sigbus:
	up_read(&mm->mmap_sem);
	info.si_signo = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRERR;
	info.si_addr = (void __user *) compute_si_addr(regs, text_fault);
	info.si_trapno = 0;
	force_sig_info (SIGBUS, &info, tsk);
	if (!from_user)
	goto no_context;

	vmalloc_fault:
	{
	/*
	* Synchronize this task's top level page-table
	* with the 'reference' page table.
	*/
	int offset = pgd_index(address);
	pgd_t pgd, pgd_k;
	pmd_t pmd, pmd_k;

	pgd = tsk->active_mm->pgd + offset;
	pgd_k = init_mm.pgd + offset;

	if (!pgd_present(*pgd)) {
	if (!pgd_present(*pgd_k))
	goto bad_area_nosemaphore;
	pgd_val(pgd) = pgd_val(pgd_k);
	return;
	}

	pmd = pmd_offset(pgd, address);
	pmd_k = pmd_offset(pgd_k, address);

	if (pmd_present(pmd) \|\| !pmd_present(pmd_k))
	goto bad_area_nosemaphore;
	pmd = pmd_k;
	return;
	}
	}

	asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
	unsigned long address)
	{
	extern void sun4c_update_mmu_cache(struct vm_area_struct *,
	unsigned long,pte_t);
	extern pte_t sun4c_pte_offset_kernel(pmd_t ,unsigned long);
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	pgd_t *pgdp;
	pte_t *ptep;

	if (text_fault) {
	address = regs->pc;
	} else if (!write &&
	!(regs->psr & PSR_PS)) {
	unsigned int insn, __user *ip;

	ip = (unsigned int __user *)regs->pc;
	if (!get_user(insn, ip)) {
	if ((insn & 0xc1680000) == 0xc0680000)
	write = 1;
	}
	}

	if (!mm) {
	/* We are oopsing. */
	do_sparc_fault(regs, text_fault, write, address);
	BUG(); /* P3 Oops already, you bitch */
	}

	pgdp = pgd_offset(mm, address);
	ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address);

	if (pgd_val(*pgdp)) {
	if (write) {
	if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE\|_SUN4C_PAGE_PRESENT))
	== (_SUN4C_PAGE_WRITE\|_SUN4C_PAGE_PRESENT)) {
	unsigned long flags;

	ptep = __pte(pte_val(ptep) \| _SUN4C_PAGE_ACCESSED \|
	_SUN4C_PAGE_MODIFIED \|
	_SUN4C_PAGE_VALID \|
	_SUN4C_PAGE_DIRTY);

	local_irq_save(flags);
	if (sun4c_get_segmap(address) != invalid_segment) {
	sun4c_put_pte(address, pte_val(*ptep));
	local_irq_restore(flags);
	return;
	}
	local_irq_restore(flags);
	}
	} else {
	if ((pte_val(*ptep) & (_SUN4C_PAGE_READ\|_SUN4C_PAGE_PRESENT))
	== (_SUN4C_PAGE_READ\|_SUN4C_PAGE_PRESENT)) {
	unsigned long flags;

	ptep = __pte(pte_val(ptep) \| _SUN4C_PAGE_ACCESSED \|
	_SUN4C_PAGE_VALID);

	local_irq_save(flags);
	if (sun4c_get_segmap(address) != invalid_segment) {
	sun4c_put_pte(address, pte_val(*ptep));
	local_irq_restore(flags);
	return;
	}
	local_irq_restore(flags);
	}
	}
	}

	/* This conditional is 'interesting'. */
	if (pgd_val(pgdp) && !(write && !(pte_val(ptep) & _SUN4C_PAGE_WRITE))
	&& (pte_val(*ptep) & _SUN4C_PAGE_VALID))
	/* Note: It is safe to not grab the MMAP semaphore here because
	* we know that update_mmu_cache() will not sleep for
	* any reason (at least not in the current implementation)
	* and therefore there is no danger of another thread getting
	* on the CPU and doing a shrink_mmap() on this vma.
	*/
	sun4c_update_mmu_cache (find_vma(current->mm, address), address,
	*ptep);
	else
	do_sparc_fault(regs, text_fault, write, address);
	}

	/* This always deals with user addresses. */
	inline void force_user_fault(unsigned long address, int write)
	{
	struct vm_area_struct *vma;
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	siginfo_t info;

	info.si_code = SEGV_MAPERR;

	#if 0
	printk("wf<pid=%d,wr=%d,addr=%08lx>\n",
	tsk->pid, write, address);
	#endif
	down_read(&mm->mmap_sem);
	vma = find_vma(mm, address);
	if(!vma)
	goto bad_area;
	if(vma->vm_start <= address)
	goto good_area;
	if(!(vma->vm_flags & VM_GROWSDOWN))
	goto bad_area;
	if(expand_stack(vma, address))
	goto bad_area;
	good_area:
	info.si_code = SEGV_ACCERR;
	if(write) {
	if(!(vma->vm_flags & VM_WRITE))
	goto bad_area;
	} else {
	if(!(vma->vm_flags & (VM_READ \| VM_EXEC)))
	goto bad_area;
	}
	switch (handle_mm_fault(mm, vma, address, write)) {
	case VM_FAULT_SIGBUS:
	case VM_FAULT_OOM:
	goto do_sigbus;
	}
	up_read(&mm->mmap_sem);
	return;
	bad_area:
	up_read(&mm->mmap_sem);
	#if 0
	printk("Window whee %s [%d]: segfaults at %08lx\n",
	tsk->comm, tsk->pid, address);
	#endif
	info.si_signo = SIGSEGV;
	info.si_errno = 0;
	/* info.si_code set above to make clear whether
	this was a SEGV_MAPERR or SEGV_ACCERR fault. */
	info.si_addr = (void __user *) address;
	info.si_trapno = 0;
	force_sig_info (SIGSEGV, &info, tsk);
	return;

	do_sigbus:
	up_read(&mm->mmap_sem);
	info.si_signo = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRERR;
	info.si_addr = (void __user *) address;
	info.si_trapno = 0;
	force_sig_info (SIGBUS, &info, tsk);
	}

	void window_overflow_fault(void)
	{
	unsigned long sp;

	sp = current_thread_info()->rwbuf_stkptrs[0];
	if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
	force_user_fault(sp + 0x38, 1);
	force_user_fault(sp, 1);
	}

	void window_underflow_fault(unsigned long sp)
	{
	if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
	force_user_fault(sp + 0x38, 0);
	force_user_fault(sp, 0);
	}

	void window_ret_fault(struct pt_regs *regs)
	{
	unsigned long sp;

	sp = regs->u_regs[UREG_FP];
	if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
	force_user_fault(sp + 0x38, 0);
	force_user_fault(sp, 0);
	}