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

 /*
  * Page fault handler for SH with an MMU.
  *
  *  Copyright (C) 1999  Niibe Yutaka
  *  Copyright (C) 2003  Paul Mundt
  *
  *  Based on linux/arch/i386/mm/fault.c:
  *   Copyright (C) 1995  Linus Torvalds
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  */
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/hardirq.h>
 #include <linux/kprobes.h>
 #include <asm/system.h>
 #include <asm/mmu_context.h>
 #include <asm/kgdb.h>

 extern void die(const char *,struct pt_regs *,long);

 /*
  * This routine handles page faults.  It determines the address,
  * and the problem, and then passes it off to one of the appropriate
  * routines.
  */
 asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
 					unsigned long writeaccess,
 					unsigned long address)
 {
 	struct task_struct *tsk;
 	struct mm_struct *mm;
 	struct vm_area_struct * vma;
 	unsigned long page;
 	int si_code;
 	siginfo_t info;

 #ifdef CONFIG_SH_KGDB
 	if (kgdb_nofault && kgdb_bus_err_hook)
 		kgdb_bus_err_hook();
 #endif

 	tsk = current;
 	mm = tsk->mm;
 	si_code = SEGV_MAPERR;

 	if (unlikely(address >= TASK_SIZE)) {
 		/*
 		 * Synchronize this task's top level page-table
 		 * with the 'reference' page table.
 		 *
 		 * Do _not_ use "tsk" here. We might be inside
 		 * an interrupt in the middle of a task switch..
 		 */
 		int offset = pgd_index(address);
 		pgd_t *pgd, *pgd_k;
 		pud_t *pud, *pud_k;
 		pmd_t *pmd, *pmd_k;

 		pgd = get_TTB() + offset;
 		pgd_k = swapper_pg_dir + offset;

 		/* This will never happen with the folded page table. */
 		if (!pgd_present(*pgd)) {
 			if (!pgd_present(*pgd_k))
 				goto bad_area_nosemaphore;
 			set_pgd(pgd, *pgd_k);
 			return;
 		}

 		pud = pud_offset(pgd, address);
 		pud_k = pud_offset(pgd_k, address);
 		if (pud_present(*pud) || !pud_present(*pud_k))
 			goto bad_area_nosemaphore;
 		set_pud(pud, *pud_k);

 		pmd = pmd_offset(pud, address);
 		pmd_k = pmd_offset(pud_k, address);
 		if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 			goto bad_area_nosemaphore;
 		set_pmd(pmd, *pmd_k);

 		return;
 	}

 	/*
 	 * 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);

 	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:
 	si_code = SEGV_ACCERR;
 	if (writeaccess) {
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
 	} else {
 		if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 			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.
 	 */
 survive:
 	switch (handle_mm_fault(mm, vma, address, writeaccess)) {
 		case VM_FAULT_MINOR:
 			tsk->min_flt++;
 			break;
 		case VM_FAULT_MAJOR:
 			tsk->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);
 	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:
 	if (user_mode(regs)) {
 		info.si_signo = SIGSEGV;
 		info.si_errno = 0;
 		info.si_code = si_code;
 		info.si_addr = (void *) address;
 		force_sig_info(SIGSEGV, &info, tsk);
 		return;
 	}

 no_context:
 	/* Are we prepared to handle this kernel fault?  */
 	if (fixup_exception(regs))
 		return;

 /*
  * Oops. The kernel tried to access some bad page. We'll have to
  * terminate things with extreme prejudice.
  *
  */
 	if (address < PAGE_SIZE)
 		printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
 	else
 		printk(KERN_ALERT "Unable to handle kernel paging request");
 	printk(" at virtual address %08lx\n", address);
 	printk(KERN_ALERT "pc = %08lx\n", regs->pc);
 	asm volatile("mov.l	%1, %0"
 		     : "=r" (page)
 		     : "m" (__m(MMU_TTB)));
 	if (page) {
 		page = ((unsigned long *) page)[address >> 22];
 		printk(KERN_ALERT "*pde = %08lx\n", page);
 		if (page & _PAGE_PRESENT) {
 			page &= PAGE_MASK;
 			address &= 0x003ff000;
 			page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
 			printk(KERN_ALERT "*pte = %08lx\n", page);
 		}
 	}
 	die("Oops", regs, writeaccess);
 	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);
 	if (is_init(current)) {
 		yield();
 		down_read(&mm->mmap_sem);
 		goto survive;
 	}
 	printk("VM: killing process %s\n", tsk->comm);
 	if (user_mode(regs))
 		do_exit(SIGKILL);
 	goto no_context;

 do_sigbus:
 	up_read(&mm->mmap_sem);

 	/*
 	 * Send a sigbus, regardless of whether we were in kernel
 	 * or user mode.
 	 */
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;
 	info.si_code = BUS_ADRERR;
 	info.si_addr = (void *)address;
 	force_sig_info(SIGBUS, &info, tsk);

 	/* Kernel mode? Handle exceptions or die */
 	if (!user_mode(regs))
 		goto no_context;
 }

 #ifdef CONFIG_SH_STORE_QUEUES
 /*
  * This is a special case for the SH-4 store queues, as pages for this
  * space still need to be faulted in before it's possible to flush the
  * store queue cache for writeout to the remapped region.
  */
 #define P3_ADDR_MAX		(P4SEG_STORE_QUE + 0x04000000)
 #else
 #define P3_ADDR_MAX		P4SEG
 #endif

 /*
  * Called with interrupts disabled.
  */
 asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
 					 unsigned long writeaccess,
 					 unsigned long address)
 {
 	pgd_t *pgd;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
 	pte_t entry;
 	struct mm_struct *mm = current->mm;
 	spinlock_t *ptl;
 	int ret = 1;

 #ifdef CONFIG_SH_KGDB
 	if (kgdb_nofault && kgdb_bus_err_hook)
 		kgdb_bus_err_hook();
 #endif

 	/*
 	 * We don't take page faults for P1, P2, and parts of P4, these
 	 * are always mapped, whether it be due to legacy behaviour in
 	 * 29-bit mode, or due to PMB configuration in 32-bit mode.
 	 */
 	if (address >= P3SEG && address < P3_ADDR_MAX) {
 		pgd = pgd_offset_k(address);
 		mm = NULL;
 	} else {
 		if (unlikely(address >= TASK_SIZE || !mm))
 			return 1;

 		pgd = pgd_offset(mm, address);
 	}

 	pud = pud_offset(pgd, address);
 	if (pud_none_or_clear_bad(pud))
 		return 1;
 	pmd = pmd_offset(pud, address);
 	if (pmd_none_or_clear_bad(pmd))
 		return 1;

 	if (mm)
 		pte = pte_offset_map_lock(mm, pmd, address, &ptl);
 	else
 		pte = pte_offset_kernel(pmd, address);

 	entry = *pte;
 	if (unlikely(pte_none(entry) || pte_not_present(entry)))
 		goto unlock;
 	if (unlikely(writeaccess && !pte_write(entry)))
 		goto unlock;

 	if (writeaccess)
 		entry = pte_mkdirty(entry);
 	entry = pte_mkyoung(entry);

 #ifdef CONFIG_CPU_SH4
 	/*
 	 * ITLB is not affected by "ldtlb" instruction.
 	 * So, we need to flush the entry by ourselves.
 	 */
 	__flush_tlb_page(get_asid(), address & PAGE_MASK);
 #endif

 	set_pte(pte, entry);
 	update_mmu_cache(NULL, address, entry);
 	ret = 0;
 unlock:
 	if (mm)
 		pte_unmap_unlock(pte, ptl);
 	return ret;
 }
	/*
	* Page fault handler for SH with an MMU.
	*
	* Copyright (C) 1999 Niibe Yutaka
	* Copyright (C) 2003 Paul Mundt
	*
	* Based on linux/arch/i386/mm/fault.c:
	* Copyright (C) 1995 Linus Torvalds
	*
	* This file is subject to the terms and conditions of the GNU General Public
	* License. See the file "COPYING" in the main directory of this archive
	* for more details.
	*/
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/hardirq.h>
	#include <linux/kprobes.h>
	#include <asm/system.h>
	#include <asm/mmu_context.h>
	#include <asm/kgdb.h>

	extern void die(const char ,struct pt_regs ,long);

	/*
	* This routine handles page faults. It determines the address,
	* and the problem, and then passes it off to one of the appropriate
	* routines.
	*/
	asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
	unsigned long writeaccess,
	unsigned long address)
	{
	struct task_struct *tsk;
	struct mm_struct *mm;
	struct vm_area_struct * vma;
	unsigned long page;
	int si_code;
	siginfo_t info;

	#ifdef CONFIG_SH_KGDB
	if (kgdb_nofault && kgdb_bus_err_hook)
	kgdb_bus_err_hook();
	#endif

	tsk = current;
	mm = tsk->mm;
	si_code = SEGV_MAPERR;

	if (unlikely(address >= TASK_SIZE)) {
	/*
	* Synchronize this task's top level page-table
	* with the 'reference' page table.
	*
	* Do _not_ use "tsk" here. We might be inside
	* an interrupt in the middle of a task switch..
	*/
	int offset = pgd_index(address);
	pgd_t pgd, pgd_k;
	pud_t pud, pud_k;
	pmd_t pmd, pmd_k;

	pgd = get_TTB() + offset;
	pgd_k = swapper_pg_dir + offset;

	/* This will never happen with the folded page table. */
	if (!pgd_present(*pgd)) {
	if (!pgd_present(*pgd_k))
	goto bad_area_nosemaphore;
	set_pgd(pgd, *pgd_k);
	return;
	}

	pud = pud_offset(pgd, address);
	pud_k = pud_offset(pgd_k, address);
	if (pud_present(pud) \|\| !pud_present(pud_k))
	goto bad_area_nosemaphore;
	set_pud(pud, *pud_k);

	pmd = pmd_offset(pud, address);
	pmd_k = pmd_offset(pud_k, address);
	if (pmd_present(pmd) \|\| !pmd_present(pmd_k))
	goto bad_area_nosemaphore;
	set_pmd(pmd, *pmd_k);

	return;
	}

	/*
	* 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);

	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:
	si_code = SEGV_ACCERR;
	if (writeaccess) {
	if (!(vma->vm_flags & VM_WRITE))
	goto bad_area;
	} else {
	if (!(vma->vm_flags & (VM_READ \| VM_EXEC \| VM_WRITE)))
	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.
	*/
	survive:
	switch (handle_mm_fault(mm, vma, address, writeaccess)) {
	case VM_FAULT_MINOR:
	tsk->min_flt++;
	break;
	case VM_FAULT_MAJOR:
	tsk->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);
	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:
	if (user_mode(regs)) {
	info.si_signo = SIGSEGV;
	info.si_errno = 0;
	info.si_code = si_code;
	info.si_addr = (void *) address;
	force_sig_info(SIGSEGV, &info, tsk);
	return;
	}

	no_context:
	/* Are we prepared to handle this kernel fault? */
	if (fixup_exception(regs))
	return;

	/*
	* Oops. The kernel tried to access some bad page. We'll have to
	* terminate things with extreme prejudice.
	*
	*/
	if (address < PAGE_SIZE)
	printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
	else
	printk(KERN_ALERT "Unable to handle kernel paging request");
	printk(" at virtual address %08lx\n", address);
	printk(KERN_ALERT "pc = %08lx\n", regs->pc);
	asm volatile("mov.l %1, %0"
	: "=r" (page)
	: "m" (__m(MMU_TTB)));
	if (page) {
	page = ((unsigned long *) page)[address >> 22];
	printk(KERN_ALERT "*pde = %08lx\n", page);
	if (page & _PAGE_PRESENT) {
	page &= PAGE_MASK;
	address &= 0x003ff000;
	page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
	printk(KERN_ALERT "*pte = %08lx\n", page);
	}
	}
	die("Oops", regs, writeaccess);
	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);
	if (is_init(current)) {
	yield();
	down_read(&mm->mmap_sem);
	goto survive;
	}
	printk("VM: killing process %s\n", tsk->comm);
	if (user_mode(regs))
	do_exit(SIGKILL);
	goto no_context;

	do_sigbus:
	up_read(&mm->mmap_sem);

	/*
	* Send a sigbus, regardless of whether we were in kernel
	* or user mode.
	*/
	info.si_signo = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRERR;
	info.si_addr = (void *)address;
	force_sig_info(SIGBUS, &info, tsk);

	/* Kernel mode? Handle exceptions or die */
	if (!user_mode(regs))
	goto no_context;
	}

	#ifdef CONFIG_SH_STORE_QUEUES
	/*
	* This is a special case for the SH-4 store queues, as pages for this
	* space still need to be faulted in before it's possible to flush the
	* store queue cache for writeout to the remapped region.
	*/
	#define P3_ADDR_MAX (P4SEG_STORE_QUE + 0x04000000)
	#else
	#define P3_ADDR_MAX P4SEG
	#endif

	/*
	* Called with interrupts disabled.
	*/
	asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
	unsigned long writeaccess,
	unsigned long address)
	{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;
	pte_t entry;
	struct mm_struct *mm = current->mm;
	spinlock_t *ptl;
	int ret = 1;

	#ifdef CONFIG_SH_KGDB
	if (kgdb_nofault && kgdb_bus_err_hook)
	kgdb_bus_err_hook();
	#endif

	/*
	* We don't take page faults for P1, P2, and parts of P4, these
	* are always mapped, whether it be due to legacy behaviour in
	* 29-bit mode, or due to PMB configuration in 32-bit mode.
	*/
	if (address >= P3SEG && address < P3_ADDR_MAX) {
	pgd = pgd_offset_k(address);
	mm = NULL;
	} else {
	if (unlikely(address >= TASK_SIZE \|\| !mm))
	return 1;

	pgd = pgd_offset(mm, address);
	}

	pud = pud_offset(pgd, address);
	if (pud_none_or_clear_bad(pud))
	return 1;
	pmd = pmd_offset(pud, address);
	if (pmd_none_or_clear_bad(pmd))
	return 1;

	if (mm)
	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
	else
	pte = pte_offset_kernel(pmd, address);

	entry = *pte;
	if (unlikely(pte_none(entry) \|\| pte_not_present(entry)))
	goto unlock;
	if (unlikely(writeaccess && !pte_write(entry)))
	goto unlock;

	if (writeaccess)
	entry = pte_mkdirty(entry);
	entry = pte_mkyoung(entry);

	#ifdef CONFIG_CPU_SH4
	/*
	* ITLB is not affected by "ldtlb" instruction.
	* So, we need to flush the entry by ourselves.
	*/
	__flush_tlb_page(get_asid(), address & PAGE_MASK);
	#endif

	set_pte(pte, entry);
	update_mmu_cache(NULL, address, entry);
	ret = 0;
	unlock:
	if (mm)
	pte_unmap_unlock(pte, ptl);
	return ret;
	}