arch/sparc64/mm/fault.c - linux - Git at Google

 /* $Id: fault.c,v 1.59 2002/02/09 19:49:31 davem Exp $
  * arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc.
  *
  * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
  * Copyright (C) 1997, 1999 Jakub Jelinek (jj@ultra.linux.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/signal.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/smp_lock.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/kprobes.h>

 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/openprom.h>
 #include <asm/oplib.h>
 #include <asm/uaccess.h>
 #include <asm/asi.h>
 #include <asm/lsu.h>
 #include <asm/sections.h>
 #include <asm/kdebug.h>

 #define ELEMENTS(arr) (sizeof (arr)/sizeof (arr[0]))

 extern struct sparc_phys_banks sp_banks[SPARC_PHYS_BANKS];

 /*
  * To debug kernel to catch accesses to certain virtual/physical addresses.
  * Mode = 0 selects physical watchpoints, mode = 1 selects virtual watchpoints.
  * flags = VM_READ watches memread accesses, flags = VM_WRITE watches memwrite accesses.
  * Caller passes in a 64bit aligned addr, with mask set to the bytes that need to be
  * watched. This is only useful on a single cpu machine for now. After the watchpoint
  * is detected, the process causing it will be killed, thus preventing an infinite loop.
  */
 void set_brkpt(unsigned long addr, unsigned char mask, int flags, int mode)
 {
 	unsigned long lsubits;

 	__asm__ __volatile__("ldxa [%%g0] %1, %0"
 			     : "=r" (lsubits)
 			     : "i" (ASI_LSU_CONTROL));
 	lsubits &= ~(LSU_CONTROL_PM | LSU_CONTROL_VM |
 		     LSU_CONTROL_PR | LSU_CONTROL_VR |
 		     LSU_CONTROL_PW | LSU_CONTROL_VW);

 	__asm__ __volatile__("stxa	%0, [%1] %2\n\t"
 			     "membar	#Sync"
 			     : /* no outputs */
 			     : "r" (addr), "r" (mode ? VIRT_WATCHPOINT : PHYS_WATCHPOINT),
 			       "i" (ASI_DMMU));

 	lsubits |= ((unsigned long)mask << (mode ? 25 : 33));
 	if (flags & VM_READ)
 		lsubits |= (mode ? LSU_CONTROL_VR : LSU_CONTROL_PR);
 	if (flags & VM_WRITE)
 		lsubits |= (mode ? LSU_CONTROL_VW : LSU_CONTROL_PW);
 	__asm__ __volatile__("stxa %0, [%%g0] %1\n\t"
 			     "membar #Sync"
 			     : /* no outputs */
 			     : "r" (lsubits), "i" (ASI_LSU_CONTROL)
 			     : "memory");
 }

 /* Nice, simple, prom library does all the sweating for us. ;) */
 unsigned long __init prom_probe_memory (void)
 {
 	register struct linux_mlist_p1275 *mlist;
 	register unsigned long bytes, base_paddr, tally;
 	register int i;

 	i = 0;
 	mlist = *prom_meminfo()->p1275_available;
 	bytes = tally = mlist->num_bytes;
 	base_paddr = 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 = mlist->start_adr;
 		sp_banks[i].num_bytes = mlist->num_bytes;
 	}

 	i++;
 	sp_banks[i].base_addr = 0xdeadbeefbeefdeadUL;
 	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;
 }

 static void __kprobes 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 %016lx\n", (unsigned long)address);
 	}
 	printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n",
 	       (tsk->mm ?
 		CTX_HWBITS(tsk->mm->context) :
 		CTX_HWBITS(tsk->active_mm->context)));
 	printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n",
 	       (tsk->mm ? (unsigned long) tsk->mm->pgd :
 		          (unsigned long) tsk->active_mm->pgd));
 	if (notify_die(DIE_GPF, "general protection fault", regs,
 		       0, 0, SIGSEGV) == NOTIFY_STOP)
 		return;
 	die_if_kernel("Oops", regs);
 }

 static void bad_kernel_pc(struct pt_regs *regs)
 {
 	unsigned long *ksp;

 	printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n",
 	       regs->tpc);
 	__asm__("mov %%sp, %0" : "=r" (ksp));
 	show_stack(current, ksp);
 	unhandled_fault(regs->tpc, current, regs);
 }

 /*
  * We now make sure that mmap_sem is held in all paths that call
  * this. Additionally, to prevent kswapd from ripping ptes from
  * under us, raise interrupts around the time that we look at the
  * pte, kswapd will have to wait to get his smp ipi response from
  * us. This saves us having to get page_table_lock.
  */
 static unsigned int get_user_insn(unsigned long tpc)
 {
 	pgd_t *pgdp = pgd_offset(current->mm, tpc);
 	pud_t *pudp;
 	pmd_t *pmdp;
 	pte_t *ptep, pte;
 	unsigned long pa;
 	u32 insn = 0;
 	unsigned long pstate;

 	if (pgd_none(*pgdp))
 		goto outret;
 	pudp = pud_offset(pgdp, tpc);
 	if (pud_none(*pudp))
 		goto outret;
 	pmdp = pmd_offset(pudp, tpc);
 	if (pmd_none(*pmdp))
 		goto outret;

 	/* This disables preemption for us as well. */
 	__asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate));
 	__asm__ __volatile__("wrpr %0, %1, %%pstate"
 				: : "r" (pstate), "i" (PSTATE_IE));
 	ptep = pte_offset_map(pmdp, tpc);
 	pte = *ptep;
 	if (!pte_present(pte))
 		goto out;

 	pa  = (pte_val(pte) & _PAGE_PADDR);
 	pa += (tpc & ~PAGE_MASK);

 	/* Use phys bypass so we don't pollute dtlb/dcache. */
 	__asm__ __volatile__("lduwa [%1] %2, %0"
 			     : "=r" (insn)
 			     : "r" (pa), "i" (ASI_PHYS_USE_EC));

 out:
 	pte_unmap(ptep);
 	__asm__ __volatile__("wrpr %0, 0x0, %%pstate" : : "r" (pstate));
 outret:
 	return insn;
 }

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

 static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 			     unsigned int insn, int fault_code)
 {
 	siginfo_t info;

 	info.si_code = code;
 	info.si_signo = sig;
 	info.si_errno = 0;
 	if (fault_code & FAULT_CODE_ITLB)
 		info.si_addr = (void __user *) regs->tpc;
 	else
 		info.si_addr = (void __user *)
 			compute_effective_address(regs, insn, 0);
 	info.si_trapno = 0;
 	force_sig_info(sig, &info, current);
 }

 extern int handle_ldf_stq(u32, struct pt_regs *);
 extern int handle_ld_nf(u32, struct pt_regs *);

 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
 {
 	if (!insn) {
 		if (!regs->tpc || (regs->tpc & 0x3))
 			return 0;
 		if (regs->tstate & TSTATE_PRIV) {
 			insn = *(unsigned int *) regs->tpc;
 		} else {
 			insn = get_user_insn(regs->tpc);
 		}
 	}
 	return insn;
 }

 static void do_kernel_fault(struct pt_regs *regs, int si_code, int fault_code,
 			    unsigned int insn, unsigned long address)
 {
 	unsigned long g2;
 	unsigned char asi = ASI_P;

 	if ((!insn) && (regs->tstate & TSTATE_PRIV))
 		goto cannot_handle;

 	/* If user insn could be read (thus insn is zero), that
 	 * is fine.  We will just gun down the process with a signal
 	 * in that case.
 	 */

 	if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) &&
 	    (insn & 0xc0800000) == 0xc0800000) {
 		if (insn & 0x2000)
 			asi = (regs->tstate >> 24);
 		else
 			asi = (insn >> 5);
 		if ((asi & 0xf2) == 0x82) {
 			if (insn & 0x1000000) {
 				handle_ldf_stq(insn, regs);
 			} else {
 				/* This was a non-faulting load. Just clear the
 				 * destination register(s) and continue with the next
 				 * instruction. -jj
 				 */
 				handle_ld_nf(insn, regs);
 			}
 			return;
 		}
 	}

 	g2 = regs->u_regs[UREG_G2];

 	/* Is this in ex_table? */
 	if (regs->tstate & TSTATE_PRIV) {
 		unsigned long fixup;

 		if (asi == ASI_P && (insn & 0xc0800000) == 0xc0800000) {
 			if (insn & 0x2000)
 				asi = (regs->tstate >> 24);
 			else
 				asi = (insn >> 5);
 		}

 		/* Look in asi.h: All _S asis have LS bit set */
 		if ((asi & 0x1) &&
 		    (fixup = search_extables_range(regs->tpc, &g2))) {
 			regs->tpc = fixup;
 			regs->tnpc = regs->tpc + 4;
 			regs->u_regs[UREG_G2] = g2;
 			return;
 		}
 	} else {
 		/* The si_code was set to make clear whether
 		 * this was a SEGV_MAPERR or SEGV_ACCERR fault.
 		 */
 		do_fault_siginfo(si_code, SIGSEGV, regs, insn, fault_code);
 		return;
 	}

 cannot_handle:
 	unhandled_fault (address, current, regs);
 }

 asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	unsigned int insn = 0;
 	int si_code, fault_code;
 	unsigned long address;

 	fault_code = get_thread_fault_code();

 	if (notify_die(DIE_PAGE_FAULT, "page_fault", regs,
 		       fault_code, 0, SIGSEGV) == NOTIFY_STOP)
 		return;

 	si_code = SEGV_MAPERR;
 	address = current_thread_info()->fault_address;

 	if ((fault_code & FAULT_CODE_ITLB) &&
 	    (fault_code & FAULT_CODE_DTLB))
 		BUG();

 	if (regs->tstate & TSTATE_PRIV) {
 		unsigned long tpc = regs->tpc;

 		/* Sanity check the PC. */
 		if ((tpc >= KERNBASE && tpc < (unsigned long) _etext) ||
 		    (tpc >= MODULES_VADDR && tpc < MODULES_END)) {
 			/* Valid, no problems... */
 		} else {
 			bad_kernel_pc(regs);
 			return;
 		}
 	}

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

 	if (test_thread_flag(TIF_32BIT)) {
 		if (!(regs->tstate & TSTATE_PRIV))
 			regs->tpc &= 0xffffffff;
 		address &= 0xffffffff;
 	}

 	if (!down_read_trylock(&mm->mmap_sem)) {
 		if ((regs->tstate & TSTATE_PRIV) &&
 		    !search_exception_tables(regs->tpc)) {
 			insn = get_fault_insn(regs, insn);
 			goto handle_kernel_fault;
 		}
 		down_read(&mm->mmap_sem);
 	}

 	vma = find_vma(mm, address);
 	if (!vma)
 		goto bad_area;

 	/* Pure DTLB misses do not tell us whether the fault causing
 	 * load/store/atomic was a write or not, it only says that there
 	 * was no match.  So in such a case we (carefully) read the
 	 * instruction to try and figure this out.  It's an optimization
 	 * so it's ok if we can't do this.
 	 *
 	 * Special hack, window spill/fill knows the exact fault type.
 	 */
 	if (((fault_code &
 	      (FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) &&
 	    (vma->vm_flags & VM_WRITE) != 0) {
 		insn = get_fault_insn(regs, 0);
 		if (!insn)
 			goto continue_fault;
 		if ((insn & 0xc0200000) == 0xc0200000 &&
 		    (insn & 0x1780000) != 0x1680000) {
 			/* Don't bother updating thread struct value,
 			 * because update_mmu_cache only cares which tlb
 			 * the access came from.
 			 */
 			fault_code |= FAULT_CODE_WRITE;
 		}
 	}
 continue_fault:

 	if (vma->vm_start <= address)
 		goto good_area;
 	if (!(vma->vm_flags & VM_GROWSDOWN))
 		goto bad_area;
 	if (!(fault_code & FAULT_CODE_WRITE)) {
 		/* Non-faulting loads shouldn't expand stack. */
 		insn = get_fault_insn(regs, insn);
 		if ((insn & 0xc0800000) == 0xc0800000) {
 			unsigned char asi;

 			if (insn & 0x2000)
 				asi = (regs->tstate >> 24);
 			else
 				asi = (insn >> 5);
 			if ((asi & 0xf2) == 0x82)
 				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:
 	si_code = SEGV_ACCERR;

 	/* If we took a ITLB miss on a non-executable page, catch
 	 * that here.
 	 */
 	if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) {
 		BUG_ON(address != regs->tpc);
 		BUG_ON(regs->tstate & TSTATE_PRIV);
 		goto bad_area;
 	}

 	if (fault_code & FAULT_CODE_WRITE) {
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;

 		/* Spitfire has an icache which does not snoop
 		 * processor stores.  Later processors do...
 		 */
 		if (tlb_type == spitfire &&
 		    (vma->vm_flags & VM_EXEC) != 0 &&
 		    vma->vm_file != NULL)
 			set_thread_fault_code(fault_code |
 					      FAULT_CODE_BLKCOMMIT);
 	} else {
 		/* Allow reads even for write-only mappings */
 		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 			goto bad_area;
 	}

 	switch (handle_mm_fault(mm, vma, address, (fault_code & FAULT_CODE_WRITE))) {
 	case VM_FAULT_MINOR:
 		current->min_flt++;
 		break;
 	case VM_FAULT_MAJOR:
 		current->maj_flt++;
 		break;
 	case VM_FAULT_SIGBUS:
 		goto do_sigbus;
 	case VM_FAULT_OOM:
 		goto out_of_memory;
 	default:
 		BUG();
 	}

 	up_read(&mm->mmap_sem);
 	goto fault_done;

 	/*
 	 * 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:
 	insn = get_fault_insn(regs, insn);
 	up_read(&mm->mmap_sem);

 handle_kernel_fault:
 	do_kernel_fault(regs, si_code, fault_code, insn, address);

 	goto fault_done;

 /*
  * 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:
 	insn = get_fault_insn(regs, insn);
 	up_read(&mm->mmap_sem);
 	printk("VM: killing process %s\n", current->comm);
 	if (!(regs->tstate & TSTATE_PRIV))
 		do_exit(SIGKILL);
 	goto handle_kernel_fault;

 intr_or_no_mm:
 	insn = get_fault_insn(regs, 0);
 	goto handle_kernel_fault;

 do_sigbus:
 	insn = get_fault_insn(regs, insn);
 	up_read(&mm->mmap_sem);

 	/*
 	 * Send a sigbus, regardless of whether we were in kernel
 	 * or user mode.
 	 */
 	do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, insn, fault_code);

 	/* Kernel mode? Handle exceptions or die */
 	if (regs->tstate & TSTATE_PRIV)
 		goto handle_kernel_fault;

 fault_done:
 	/* These values are no longer needed, clear them. */
 	set_thread_fault_code(0);
 	current_thread_info()->fault_address = 0;
 }
	/* $Id: fault.c,v 1.59 2002/02/09 19:49:31 davem Exp $
	* arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc.
	*
	* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
	* Copyright (C) 1997, 1999 Jakub Jelinek (jj@ultra.linux.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/signal.h>
	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/smp_lock.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/kprobes.h>

	#include <asm/page.h>
	#include <asm/pgtable.h>
	#include <asm/openprom.h>
	#include <asm/oplib.h>
	#include <asm/uaccess.h>
	#include <asm/asi.h>
	#include <asm/lsu.h>
	#include <asm/sections.h>
	#include <asm/kdebug.h>

	#define ELEMENTS(arr) (sizeof (arr)/sizeof (arr[0]))

	extern struct sparc_phys_banks sp_banks[SPARC_PHYS_BANKS];

	/*
	* To debug kernel to catch accesses to certain virtual/physical addresses.
	* Mode = 0 selects physical watchpoints, mode = 1 selects virtual watchpoints.
	* flags = VM_READ watches memread accesses, flags = VM_WRITE watches memwrite accesses.
	* Caller passes in a 64bit aligned addr, with mask set to the bytes that need to be
	* watched. This is only useful on a single cpu machine for now. After the watchpoint
	* is detected, the process causing it will be killed, thus preventing an infinite loop.
	*/
	void set_brkpt(unsigned long addr, unsigned char mask, int flags, int mode)
	{
	unsigned long lsubits;

	__asm__ __volatile__("ldxa [%%g0] %1, %0"
	: "=r" (lsubits)
	: "i" (ASI_LSU_CONTROL));
	lsubits &= ~(LSU_CONTROL_PM \| LSU_CONTROL_VM \|
	LSU_CONTROL_PR \| LSU_CONTROL_VR \|
	LSU_CONTROL_PW \| LSU_CONTROL_VW);

	__asm__ __volatile__("stxa %0, [%1] %2\n\t"
	"membar #Sync"
	: /* no outputs */
	: "r" (addr), "r" (mode ? VIRT_WATCHPOINT : PHYS_WATCHPOINT),
	"i" (ASI_DMMU));

	lsubits \|= ((unsigned long)mask << (mode ? 25 : 33));
	if (flags & VM_READ)
	lsubits \|= (mode ? LSU_CONTROL_VR : LSU_CONTROL_PR);
	if (flags & VM_WRITE)
	lsubits \|= (mode ? LSU_CONTROL_VW : LSU_CONTROL_PW);
	__asm__ __volatile__("stxa %0, [%%g0] %1\n\t"
	"membar #Sync"
	: /* no outputs */
	: "r" (lsubits), "i" (ASI_LSU_CONTROL)
	: "memory");
	}

	/* Nice, simple, prom library does all the sweating for us. ;) */
	unsigned long __init prom_probe_memory (void)
	{
	register struct linux_mlist_p1275 *mlist;
	register unsigned long bytes, base_paddr, tally;
	register int i;

	i = 0;
	mlist = *prom_meminfo()->p1275_available;
	bytes = tally = mlist->num_bytes;
	base_paddr = 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 = mlist->start_adr;
	sp_banks[i].num_bytes = mlist->num_bytes;
	}

	i++;
	sp_banks[i].base_addr = 0xdeadbeefbeefdeadUL;
	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;
	}

	static void __kprobes 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 %016lx\n", (unsigned long)address);
	}
	printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n",
	(tsk->mm ?
	CTX_HWBITS(tsk->mm->context) :
	CTX_HWBITS(tsk->active_mm->context)));
	printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n",
	(tsk->mm ? (unsigned long) tsk->mm->pgd :
	(unsigned long) tsk->active_mm->pgd));
	if (notify_die(DIE_GPF, "general protection fault", regs,
	0, 0, SIGSEGV) == NOTIFY_STOP)
	return;
	die_if_kernel("Oops", regs);
	}

	static void bad_kernel_pc(struct pt_regs *regs)
	{
	unsigned long *ksp;

	printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n",
	regs->tpc);
	__asm__("mov %%sp, %0" : "=r" (ksp));
	show_stack(current, ksp);
	unhandled_fault(regs->tpc, current, regs);
	}

	/*
	* We now make sure that mmap_sem is held in all paths that call
	* this. Additionally, to prevent kswapd from ripping ptes from
	* under us, raise interrupts around the time that we look at the
	* pte, kswapd will have to wait to get his smp ipi response from
	* us. This saves us having to get page_table_lock.
	*/
	static unsigned int get_user_insn(unsigned long tpc)
	{
	pgd_t *pgdp = pgd_offset(current->mm, tpc);
	pud_t *pudp;
	pmd_t *pmdp;
	pte_t *ptep, pte;
	unsigned long pa;
	u32 insn = 0;
	unsigned long pstate;

	if (pgd_none(*pgdp))
	goto outret;
	pudp = pud_offset(pgdp, tpc);
	if (pud_none(*pudp))
	goto outret;
	pmdp = pmd_offset(pudp, tpc);
	if (pmd_none(*pmdp))
	goto outret;

	/* This disables preemption for us as well. */
	__asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate));
	__asm__ __volatile__("wrpr %0, %1, %%pstate"
	: : "r" (pstate), "i" (PSTATE_IE));
	ptep = pte_offset_map(pmdp, tpc);
	pte = *ptep;
	if (!pte_present(pte))
	goto out;

	pa = (pte_val(pte) & _PAGE_PADDR);
	pa += (tpc & ~PAGE_MASK);

	/* Use phys bypass so we don't pollute dtlb/dcache. */
	__asm__ __volatile__("lduwa [%1] %2, %0"
	: "=r" (insn)
	: "r" (pa), "i" (ASI_PHYS_USE_EC));

	out:
	pte_unmap(ptep);
	__asm__ __volatile__("wrpr %0, 0x0, %%pstate" : : "r" (pstate));
	outret:
	return insn;
	}

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

	static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
	unsigned int insn, int fault_code)
	{
	siginfo_t info;

	info.si_code = code;
	info.si_signo = sig;
	info.si_errno = 0;
	if (fault_code & FAULT_CODE_ITLB)
	info.si_addr = (void __user *) regs->tpc;
	else
	info.si_addr = (void __user *)
	compute_effective_address(regs, insn, 0);
	info.si_trapno = 0;
	force_sig_info(sig, &info, current);
	}

	extern int handle_ldf_stq(u32, struct pt_regs *);
	extern int handle_ld_nf(u32, struct pt_regs *);

	static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
	{
	if (!insn) {
	if (!regs->tpc \|\| (regs->tpc & 0x3))
	return 0;
	if (regs->tstate & TSTATE_PRIV) {
	insn = (unsigned int ) regs->tpc;
	} else {
	insn = get_user_insn(regs->tpc);
	}
	}
	return insn;
	}

	static void do_kernel_fault(struct pt_regs *regs, int si_code, int fault_code,
	unsigned int insn, unsigned long address)
	{
	unsigned long g2;
	unsigned char asi = ASI_P;

	if ((!insn) && (regs->tstate & TSTATE_PRIV))
	goto cannot_handle;

	/* If user insn could be read (thus insn is zero), that
	* is fine. We will just gun down the process with a signal
	* in that case.
	*/

	if (!(fault_code & (FAULT_CODE_WRITE\|FAULT_CODE_ITLB)) &&
	(insn & 0xc0800000) == 0xc0800000) {
	if (insn & 0x2000)
	asi = (regs->tstate >> 24);
	else
	asi = (insn >> 5);
	if ((asi & 0xf2) == 0x82) {
	if (insn & 0x1000000) {
	handle_ldf_stq(insn, regs);
	} else {
	/* This was a non-faulting load. Just clear the
	* destination register(s) and continue with the next
	* instruction. -jj
	*/
	handle_ld_nf(insn, regs);
	}
	return;
	}
	}

	g2 = regs->u_regs[UREG_G2];

	/* Is this in ex_table? */
	if (regs->tstate & TSTATE_PRIV) {
	unsigned long fixup;

	if (asi == ASI_P && (insn & 0xc0800000) == 0xc0800000) {
	if (insn & 0x2000)
	asi = (regs->tstate >> 24);
	else
	asi = (insn >> 5);
	}

	/* Look in asi.h: All _S asis have LS bit set */
	if ((asi & 0x1) &&
	(fixup = search_extables_range(regs->tpc, &g2))) {
	regs->tpc = fixup;
	regs->tnpc = regs->tpc + 4;
	regs->u_regs[UREG_G2] = g2;
	return;
	}
	} else {
	/* The si_code was set to make clear whether
	* this was a SEGV_MAPERR or SEGV_ACCERR fault.
	*/
	do_fault_siginfo(si_code, SIGSEGV, regs, insn, fault_code);
	return;
	}

	cannot_handle:
	unhandled_fault (address, current, regs);
	}

	asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
	{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned int insn = 0;
	int si_code, fault_code;
	unsigned long address;

	fault_code = get_thread_fault_code();

	if (notify_die(DIE_PAGE_FAULT, "page_fault", regs,
	fault_code, 0, SIGSEGV) == NOTIFY_STOP)
	return;

	si_code = SEGV_MAPERR;
	address = current_thread_info()->fault_address;

	if ((fault_code & FAULT_CODE_ITLB) &&
	(fault_code & FAULT_CODE_DTLB))
	BUG();

	if (regs->tstate & TSTATE_PRIV) {
	unsigned long tpc = regs->tpc;

	/* Sanity check the PC. */
	if ((tpc >= KERNBASE && tpc < (unsigned long) _etext) \|\|
	(tpc >= MODULES_VADDR && tpc < MODULES_END)) {
	/* Valid, no problems... */
	} else {
	bad_kernel_pc(regs);
	return;
	}
	}

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

	if (test_thread_flag(TIF_32BIT)) {
	if (!(regs->tstate & TSTATE_PRIV))
	regs->tpc &= 0xffffffff;
	address &= 0xffffffff;
	}

	if (!down_read_trylock(&mm->mmap_sem)) {
	if ((regs->tstate & TSTATE_PRIV) &&
	!search_exception_tables(regs->tpc)) {
	insn = get_fault_insn(regs, insn);
	goto handle_kernel_fault;
	}
	down_read(&mm->mmap_sem);
	}

	vma = find_vma(mm, address);
	if (!vma)
	goto bad_area;

	/* Pure DTLB misses do not tell us whether the fault causing
	* load/store/atomic was a write or not, it only says that there
	* was no match. So in such a case we (carefully) read the
	* instruction to try and figure this out. It's an optimization
	* so it's ok if we can't do this.
	*
	* Special hack, window spill/fill knows the exact fault type.
	*/
	if (((fault_code &
	(FAULT_CODE_DTLB \| FAULT_CODE_WRITE \| FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) &&
	(vma->vm_flags & VM_WRITE) != 0) {
	insn = get_fault_insn(regs, 0);
	if (!insn)
	goto continue_fault;
	if ((insn & 0xc0200000) == 0xc0200000 &&
	(insn & 0x1780000) != 0x1680000) {
	/* Don't bother updating thread struct value,
	* because update_mmu_cache only cares which tlb
	* the access came from.
	*/
	fault_code \|= FAULT_CODE_WRITE;
	}
	}
	continue_fault:

	if (vma->vm_start <= address)
	goto good_area;
	if (!(vma->vm_flags & VM_GROWSDOWN))
	goto bad_area;
	if (!(fault_code & FAULT_CODE_WRITE)) {
	/* Non-faulting loads shouldn't expand stack. */
	insn = get_fault_insn(regs, insn);
	if ((insn & 0xc0800000) == 0xc0800000) {
	unsigned char asi;

	if (insn & 0x2000)
	asi = (regs->tstate >> 24);
	else
	asi = (insn >> 5);
	if ((asi & 0xf2) == 0x82)
	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:
	si_code = SEGV_ACCERR;

	/* If we took a ITLB miss on a non-executable page, catch
	* that here.
	*/
	if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) {
	BUG_ON(address != regs->tpc);
	BUG_ON(regs->tstate & TSTATE_PRIV);
	goto bad_area;
	}

	if (fault_code & FAULT_CODE_WRITE) {
	if (!(vma->vm_flags & VM_WRITE))
	goto bad_area;

	/* Spitfire has an icache which does not snoop
	* processor stores. Later processors do...
	*/
	if (tlb_type == spitfire &&
	(vma->vm_flags & VM_EXEC) != 0 &&
	vma->vm_file != NULL)
	set_thread_fault_code(fault_code \|
	FAULT_CODE_BLKCOMMIT);
	} else {
	/* Allow reads even for write-only mappings */
	if (!(vma->vm_flags & (VM_READ \| VM_EXEC)))
	goto bad_area;
	}

	switch (handle_mm_fault(mm, vma, address, (fault_code & FAULT_CODE_WRITE))) {
	case VM_FAULT_MINOR:
	current->min_flt++;
	break;
	case VM_FAULT_MAJOR:
	current->maj_flt++;
	break;
	case VM_FAULT_SIGBUS:
	goto do_sigbus;
	case VM_FAULT_OOM:
	goto out_of_memory;
	default:
	BUG();
	}

	up_read(&mm->mmap_sem);
	goto fault_done;

	/*
	* 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:
	insn = get_fault_insn(regs, insn);
	up_read(&mm->mmap_sem);

	handle_kernel_fault:
	do_kernel_fault(regs, si_code, fault_code, insn, address);

	goto fault_done;

	/*
	* 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:
	insn = get_fault_insn(regs, insn);
	up_read(&mm->mmap_sem);
	printk("VM: killing process %s\n", current->comm);
	if (!(regs->tstate & TSTATE_PRIV))
	do_exit(SIGKILL);
	goto handle_kernel_fault;

	intr_or_no_mm:
	insn = get_fault_insn(regs, 0);
	goto handle_kernel_fault;

	do_sigbus:
	insn = get_fault_insn(regs, insn);
	up_read(&mm->mmap_sem);

	/*
	* Send a sigbus, regardless of whether we were in kernel
	* or user mode.
	*/
	do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, insn, fault_code);

	/* Kernel mode? Handle exceptions or die */
	if (regs->tstate & TSTATE_PRIV)
	goto handle_kernel_fault;

	fault_done:
	/* These values are no longer needed, clear them. */
	set_thread_fault_code(0);
	current_thread_info()->fault_address = 0;
	}