arch/sparc/mm/fault_64.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc.
  *
  * Copyright (C) 1996, 2008 David S. Miller (davem@davemloft.net)
  * 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/sched/debug.h>
 #include <linux/ptrace.h>
 #include <linux/mman.h>
 #include <linux/signal.h>
 #include <linux/mm.h>
 #include <linux/extable.h>
 #include <linux/init.h>
 #include <linux/perf_event.h>
 #include <linux/interrupt.h>
 #include <linux/kprobes.h>
 #include <linux/kdebug.h>
 #include <linux/percpu.h>
 #include <linux/context_tracking.h>
 #include <linux/uaccess.h>

 #include <asm/page.h>
 #include <asm/openprom.h>
 #include <asm/oplib.h>
 #include <asm/asi.h>
 #include <asm/lsu.h>
 #include <asm/sections.h>
 #include <asm/mmu_context.h>
 #include <asm/setup.h>

 int show_unhandled_signals = 1;

 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));
 	die_if_kernel("Oops", regs);
 }

 static void __kprobes bad_kernel_pc(struct pt_regs *regs, unsigned long vaddr)
 {
 	printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n",
 	       regs->tpc);
 	printk(KERN_CRIT "OOPS: RPC [%016lx]\n", regs->u_regs[15]);
 	printk("OOPS: RPC <%pS>\n", (void *) regs->u_regs[15]);
 	printk(KERN_CRIT "OOPS: Fault was to vaddr[%lx]\n", vaddr);
 	dump_stack();
 	unhandled_fault(regs->tpc, current, regs);
 }

 /*
  * We now make sure that mmap_lock 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. vmtruncate likewise. This saves us having to get pte lock.
  */
 static unsigned int get_user_insn(unsigned long tpc)
 {
 	pgd_t *pgdp = pgd_offset(current->mm, tpc);
 	p4d_t *p4dp;
 	pud_t *pudp;
 	pmd_t *pmdp;
 	pte_t *ptep, pte;
 	unsigned long pa;
 	u32 insn = 0;

 	if (pgd_none(*pgdp) || unlikely(pgd_bad(*pgdp)))
 		goto out;
 	p4dp = p4d_offset(pgdp, tpc);
 	if (p4d_none(*p4dp) || unlikely(p4d_bad(*p4dp)))
 		goto out;
 	pudp = pud_offset(p4dp, tpc);
 	if (pud_none(*pudp) || unlikely(pud_bad(*pudp)))
 		goto out;

 	/* This disables preemption for us as well. */
 	local_irq_disable();

 	pmdp = pmd_offset(pudp, tpc);
 	if (pmd_none(*pmdp) || unlikely(pmd_bad(*pmdp)))
 		goto out_irq_enable;

 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
 	if (is_hugetlb_pmd(*pmdp)) {
 		pa  = pmd_pfn(*pmdp) << PAGE_SHIFT;
 		pa += tpc & ~HPAGE_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));
 	} else
 #endif
 	{
 		ptep = pte_offset_map(pmdp, tpc);
 		pte = *ptep;
 		if (pte_present(pte)) {
 			pa  = (pte_pfn(pte) << PAGE_SHIFT);
 			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));
 		}
 		pte_unmap(ptep);
 	}
 out_irq_enable:
 	local_irq_enable();
 out:
 	return insn;
 }

 static inline void
 show_signal_msg(struct pt_regs *regs, int sig, int code,
 		unsigned long address, struct task_struct *tsk)
 {
 	if (!unhandled_signal(tsk, sig))
 		return;

 	if (!printk_ratelimit())
 		return;

 	printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x",
 	       task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 	       tsk->comm, task_pid_nr(tsk), address,
 	       (void *)regs->tpc, (void *)regs->u_regs[UREG_I7],
 	       (void *)regs->u_regs[UREG_FP], code);

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

 	printk(KERN_CONT "\n");
 }

 static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 			     unsigned long fault_addr, unsigned int insn,
 			     int fault_code)
 {
 	unsigned long addr;

 	if (fault_code & FAULT_CODE_ITLB) {
 		addr = regs->tpc;
 	} else {
 		/* If we were able to probe the faulting instruction, use it
 		 * to compute a precise fault address.  Otherwise use the fault
 		 * time provided address which may only have page granularity.
 		 */
 		if (insn)
 			addr = compute_effective_address(regs, insn, 0);
 		else
 			addr = fault_addr;
 	}

 	if (unlikely(show_unhandled_signals))
 		show_signal_msg(regs, sig, code, addr, current);

 	force_sig_fault(sig, code, (void __user *) addr);
 }

 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 __kprobes do_kernel_fault(struct pt_regs *regs, int si_code,
 				      int fault_code, unsigned int insn,
 				      unsigned long address)
 {
 	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;
 		}
 	}

 	/* Is this in ex_table? */
 	if (regs->tstate & TSTATE_PRIV) {
 		const struct exception_table_entry *entry;

 		entry = search_exception_tables(regs->tpc);
 		if (entry) {
 			regs->tpc = entry->fixup;
 			regs->tnpc = regs->tpc + 4;
 			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, address, insn, fault_code);
 		return;
 	}

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

 static void noinline __kprobes bogus_32bit_fault_tpc(struct pt_regs *regs)
 {
 	static int times;

 	if (times++ < 10)
 		printk(KERN_ERR "FAULT[%s:%d]: 32-bit process reports "
 		       "64-bit TPC [%lx]\n",
 		       current->comm, current->pid,
 		       regs->tpc);
 	show_regs(regs);
 }

 asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
 {
 	enum ctx_state prev_state = exception_enter();
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	unsigned int insn = 0;
 	int si_code, fault_code;
 	vm_fault_t fault;
 	unsigned long address, mm_rss;
 	unsigned int flags = FAULT_FLAG_DEFAULT;

 	fault_code = get_thread_fault_code();

 	if (kprobe_page_fault(regs, 0))
 		goto exit_exception;

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

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

 	if (test_thread_flag(TIF_32BIT)) {
 		if (!(regs->tstate & TSTATE_PRIV)) {
 			if (unlikely((regs->tpc >> 32) != 0)) {
 				bogus_32bit_fault_tpc(regs);
 				goto intr_or_no_mm;
 			}
 		}
 		if (unlikely((address >> 32) != 0))
 			goto intr_or_no_mm;
 	}

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

 		/* Sanity check the PC. */
 		if ((tpc >= KERNBASE && tpc < (unsigned long) __init_end) ||
 		    (tpc >= MODULES_VADDR && tpc < MODULES_END)) {
 			/* Valid, no problems... */
 		} else {
 			bad_kernel_pc(regs, address);
 			goto exit_exception;
 		}
 	} else
 		flags |= FAULT_FLAG_USER;

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

 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);

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

 retry:
 		mmap_read_lock(mm);
 	}

 	if (fault_code & FAULT_CODE_BAD_RA)
 		goto do_sigbus;

 	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;
 		/* All loads, stores and atomics have bits 30 and 31 both set
 		 * in the instruction.  Bit 21 is set in all stores, but we
 		 * have to avoid prefetches which also have bit 21 set.
 		 */
 		if ((insn & 0xc0200000) == 0xc0200000 &&
 		    (insn & 0x01780000) != 0x01680000) {
 			/* 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)) {
 		WARN(address != regs->tpc,
 		     "address (%lx) != regs->tpc (%lx)\n", address, regs->tpc);
 		WARN_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);

 		flags |= FAULT_FLAG_WRITE;
 	} else {
 		/* Allow reads even for write-only mappings */
 		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 			goto bad_area;
 	}

 	fault = handle_mm_fault(vma, address, flags, regs);

 	if (fault_signal_pending(fault, regs))
 		goto exit_exception;

 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
 		else if (fault & VM_FAULT_SIGSEGV)
 			goto bad_area;
 		else if (fault & VM_FAULT_SIGBUS)
 			goto do_sigbus;
 		BUG();
 	}

 	if (flags & FAULT_FLAG_ALLOW_RETRY) {
 		if (fault & VM_FAULT_RETRY) {
 			flags |= FAULT_FLAG_TRIED;

 			/* No need to mmap_read_unlock(mm) as we would
 			 * have already released it in __lock_page_or_retry
 			 * in mm/filemap.c.
 			 */

 			goto retry;
 		}
 	}
 	mmap_read_unlock(mm);

 	mm_rss = get_mm_rss(mm);
 #if defined(CONFIG_TRANSPARENT_HUGEPAGE)
 	mm_rss -= (mm->context.thp_pte_count * (HPAGE_SIZE / PAGE_SIZE));
 #endif
 	if (unlikely(mm_rss >
 		     mm->context.tsb_block[MM_TSB_BASE].tsb_rss_limit))
 		tsb_grow(mm, MM_TSB_BASE, mm_rss);
 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
 	mm_rss = mm->context.hugetlb_pte_count + mm->context.thp_pte_count;
 	mm_rss *= REAL_HPAGE_PER_HPAGE;
 	if (unlikely(mm_rss >
 		     mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) {
 		if (mm->context.tsb_block[MM_TSB_HUGE].tsb)
 			tsb_grow(mm, MM_TSB_HUGE, mm_rss);
 		else
 			hugetlb_setup(regs);

 	}
 #endif
 exit_exception:
 	exception_exit(prev_state);
 	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:
 	insn = get_fault_insn(regs, insn);
 	mmap_read_unlock(mm);

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

 /*
  * 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);
 	mmap_read_unlock(mm);
 	if (!(regs->tstate & TSTATE_PRIV)) {
 		pagefault_out_of_memory();
 		goto exit_exception;
 	}
 	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);
 	mmap_read_unlock(mm);

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

 	/* Kernel mode? Handle exceptions or die */
 	if (regs->tstate & TSTATE_PRIV)
 		goto handle_kernel_fault;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc.
	*
	* Copyright (C) 1996, 2008 David S. Miller (davem@davemloft.net)
	* 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/sched/debug.h>
	#include <linux/ptrace.h>
	#include <linux/mman.h>
	#include <linux/signal.h>
	#include <linux/mm.h>
	#include <linux/extable.h>
	#include <linux/init.h>
	#include <linux/perf_event.h>
	#include <linux/interrupt.h>
	#include <linux/kprobes.h>
	#include <linux/kdebug.h>
	#include <linux/percpu.h>
	#include <linux/context_tracking.h>
	#include <linux/uaccess.h>

	#include <asm/page.h>
	#include <asm/openprom.h>
	#include <asm/oplib.h>
	#include <asm/asi.h>
	#include <asm/lsu.h>
	#include <asm/sections.h>
	#include <asm/mmu_context.h>
	#include <asm/setup.h>

	int show_unhandled_signals = 1;

	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));
	die_if_kernel("Oops", regs);
	}

	static void __kprobes bad_kernel_pc(struct pt_regs *regs, unsigned long vaddr)
	{
	printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n",
	regs->tpc);
	printk(KERN_CRIT "OOPS: RPC [%016lx]\n", regs->u_regs[15]);
	printk("OOPS: RPC <%pS>\n", (void *) regs->u_regs[15]);
	printk(KERN_CRIT "OOPS: Fault was to vaddr[%lx]\n", vaddr);
	dump_stack();
	unhandled_fault(regs->tpc, current, regs);
	}

	/*
	* We now make sure that mmap_lock 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. vmtruncate likewise. This saves us having to get pte lock.
	*/
	static unsigned int get_user_insn(unsigned long tpc)
	{
	pgd_t *pgdp = pgd_offset(current->mm, tpc);
	p4d_t *p4dp;
	pud_t *pudp;
	pmd_t *pmdp;
	pte_t *ptep, pte;
	unsigned long pa;
	u32 insn = 0;

	if (pgd_none(pgdp) \|\| unlikely(pgd_bad(pgdp)))
	goto out;
	p4dp = p4d_offset(pgdp, tpc);
	if (p4d_none(p4dp) \|\| unlikely(p4d_bad(p4dp)))
	goto out;
	pudp = pud_offset(p4dp, tpc);
	if (pud_none(pudp) \|\| unlikely(pud_bad(pudp)))
	goto out;

	/* This disables preemption for us as well. */
	local_irq_disable();

	pmdp = pmd_offset(pudp, tpc);
	if (pmd_none(pmdp) \|\| unlikely(pmd_bad(pmdp)))
	goto out_irq_enable;

	#if defined(CONFIG_HUGETLB_PAGE) \|\| defined(CONFIG_TRANSPARENT_HUGEPAGE)
	if (is_hugetlb_pmd(*pmdp)) {
	pa = pmd_pfn(*pmdp) << PAGE_SHIFT;
	pa += tpc & ~HPAGE_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));
	} else
	#endif
	{
	ptep = pte_offset_map(pmdp, tpc);
	pte = *ptep;
	if (pte_present(pte)) {
	pa = (pte_pfn(pte) << PAGE_SHIFT);
	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));
	}
	pte_unmap(ptep);
	}
	out_irq_enable:
	local_irq_enable();
	out:
	return insn;
	}

	static inline void
	show_signal_msg(struct pt_regs *regs, int sig, int code,
	unsigned long address, struct task_struct *tsk)
	{
	if (!unhandled_signal(tsk, sig))
	return;

	if (!printk_ratelimit())
	return;

	printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x",
	task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
	tsk->comm, task_pid_nr(tsk), address,
	(void )regs->tpc, (void )regs->u_regs[UREG_I7],
	(void *)regs->u_regs[UREG_FP], code);

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

	printk(KERN_CONT "\n");
	}

	static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
	unsigned long fault_addr, unsigned int insn,
	int fault_code)
	{
	unsigned long addr;

	if (fault_code & FAULT_CODE_ITLB) {
	addr = regs->tpc;
	} else {
	/* If we were able to probe the faulting instruction, use it
	* to compute a precise fault address. Otherwise use the fault
	* time provided address which may only have page granularity.
	*/
	if (insn)
	addr = compute_effective_address(regs, insn, 0);
	else
	addr = fault_addr;
	}

	if (unlikely(show_unhandled_signals))
	show_signal_msg(regs, sig, code, addr, current);

	force_sig_fault(sig, code, (void __user *) addr);
	}

	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 __kprobes do_kernel_fault(struct pt_regs *regs, int si_code,
	int fault_code, unsigned int insn,
	unsigned long address)
	{
	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;
	}
	}

	/* Is this in ex_table? */
	if (regs->tstate & TSTATE_PRIV) {
	const struct exception_table_entry *entry;

	entry = search_exception_tables(regs->tpc);
	if (entry) {
	regs->tpc = entry->fixup;
	regs->tnpc = regs->tpc + 4;
	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, address, insn, fault_code);
	return;
	}

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

	static void noinline __kprobes bogus_32bit_fault_tpc(struct pt_regs *regs)
	{
	static int times;

	if (times++ < 10)
	printk(KERN_ERR "FAULT[%s:%d]: 32-bit process reports "
	"64-bit TPC [%lx]\n",
	current->comm, current->pid,
	regs->tpc);
	show_regs(regs);
	}

	asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
	{
	enum ctx_state prev_state = exception_enter();
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned int insn = 0;
	int si_code, fault_code;
	vm_fault_t fault;
	unsigned long address, mm_rss;
	unsigned int flags = FAULT_FLAG_DEFAULT;

	fault_code = get_thread_fault_code();

	if (kprobe_page_fault(regs, 0))
	goto exit_exception;

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

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

	if (test_thread_flag(TIF_32BIT)) {
	if (!(regs->tstate & TSTATE_PRIV)) {
	if (unlikely((regs->tpc >> 32) != 0)) {
	bogus_32bit_fault_tpc(regs);
	goto intr_or_no_mm;
	}
	}
	if (unlikely((address >> 32) != 0))
	goto intr_or_no_mm;
	}

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

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

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

	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);

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

	retry:
	mmap_read_lock(mm);
	}

	if (fault_code & FAULT_CODE_BAD_RA)
	goto do_sigbus;

	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;
	/* All loads, stores and atomics have bits 30 and 31 both set
	* in the instruction. Bit 21 is set in all stores, but we
	* have to avoid prefetches which also have bit 21 set.
	*/
	if ((insn & 0xc0200000) == 0xc0200000 &&
	(insn & 0x01780000) != 0x01680000) {
	/* 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)) {
	WARN(address != regs->tpc,
	"address (%lx) != regs->tpc (%lx)\n", address, regs->tpc);
	WARN_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);

	flags \|= FAULT_FLAG_WRITE;
	} else {
	/* Allow reads even for write-only mappings */
	if (!(vma->vm_flags & (VM_READ \| VM_EXEC)))
	goto bad_area;
	}

	fault = handle_mm_fault(vma, address, flags, regs);

	if (fault_signal_pending(fault, regs))
	goto exit_exception;

	if (unlikely(fault & VM_FAULT_ERROR)) {
	if (fault & VM_FAULT_OOM)
	goto out_of_memory;
	else if (fault & VM_FAULT_SIGSEGV)
	goto bad_area;
	else if (fault & VM_FAULT_SIGBUS)
	goto do_sigbus;
	BUG();
	}

	if (flags & FAULT_FLAG_ALLOW_RETRY) {
	if (fault & VM_FAULT_RETRY) {
	flags \|= FAULT_FLAG_TRIED;

	/* No need to mmap_read_unlock(mm) as we would
	* have already released it in __lock_page_or_retry
	* in mm/filemap.c.
	*/

	goto retry;
	}
	}
	mmap_read_unlock(mm);

	mm_rss = get_mm_rss(mm);
	#if defined(CONFIG_TRANSPARENT_HUGEPAGE)
	mm_rss -= (mm->context.thp_pte_count * (HPAGE_SIZE / PAGE_SIZE));
	#endif
	if (unlikely(mm_rss >
	mm->context.tsb_block[MM_TSB_BASE].tsb_rss_limit))
	tsb_grow(mm, MM_TSB_BASE, mm_rss);
	#if defined(CONFIG_HUGETLB_PAGE) \|\| defined(CONFIG_TRANSPARENT_HUGEPAGE)
	mm_rss = mm->context.hugetlb_pte_count + mm->context.thp_pte_count;
	mm_rss *= REAL_HPAGE_PER_HPAGE;
	if (unlikely(mm_rss >
	mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) {
	if (mm->context.tsb_block[MM_TSB_HUGE].tsb)
	tsb_grow(mm, MM_TSB_HUGE, mm_rss);
	else
	hugetlb_setup(regs);

	}
	#endif
	exit_exception:
	exception_exit(prev_state);
	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:
	insn = get_fault_insn(regs, insn);
	mmap_read_unlock(mm);

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

	/*
	* 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);
	mmap_read_unlock(mm);
	if (!(regs->tstate & TSTATE_PRIV)) {
	pagefault_out_of_memory();
	goto exit_exception;
	}
	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);
	mmap_read_unlock(mm);

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

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