arch/sh/mm/fault_32.c - linux - Git at Google

 /*
  * Page fault handler for SH with an MMU.
  *
  *  Copyright (C) 1999  Niibe Yutaka
  *  Copyright (C) 2003 - 2009  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 <linux/perf_counter.h>
 #include <asm/io_trapped.h>
 #include <asm/system.h>
 #include <asm/mmu_context.h>
 #include <asm/tlbflush.h>

 static inline int notify_page_fault(struct pt_regs *regs, int trap)
 {
 	int ret = 0;

 	if (kprobes_built_in() && !user_mode(regs)) {
 		preempt_disable();
 		if (kprobe_running() && kprobe_fault_handler(regs, trap))
 			ret = 1;
 		preempt_enable();
 	}

 	return ret;
 }

 static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
 {
 	unsigned index = pgd_index(address);
 	pgd_t *pgd_k;
 	pud_t *pud, *pud_k;
 	pmd_t *pmd, *pmd_k;

 	pgd += index;
 	pgd_k = init_mm.pgd + index;

 	if (!pgd_present(*pgd_k))
 		return NULL;

 	pud = pud_offset(pgd, address);
 	pud_k = pud_offset(pgd_k, address);
 	if (!pud_present(*pud_k))
 		return NULL;

 	pmd = pmd_offset(pud, address);
 	pmd_k = pmd_offset(pud_k, address);
 	if (!pmd_present(*pmd_k))
 		return NULL;

 	if (!pmd_present(*pmd))
 		set_pmd(pmd, *pmd_k);
 	else {
 		/*
 		 * The page tables are fully synchronised so there must
 		 * be another reason for the fault. Return NULL here to
 		 * signal that we have not taken care of the fault.
 		 */
 		BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
 		return NULL;
 	}

 	return pmd_k;
 }

 /*
  * Handle a fault on the vmalloc or module mapping area
  */
 static noinline int vmalloc_fault(unsigned long address)
 {
 	pgd_t *pgd_k;
 	pmd_t *pmd_k;
 	pte_t *pte_k;

 	/* Make sure we are in vmalloc area: */
 	if (!(address >= VMALLOC_START && address < VMALLOC_END))
 		return -1;

 	/*
 	 * Synchronize this task's top level page-table
 	 * with the 'reference' page table.
 	 *
 	 * Do _not_ use "current" here. We might be inside
 	 * an interrupt in the middle of a task switch..
 	 */
 	pgd_k = get_TTB();
 	pmd_k = vmalloc_sync_one(pgd_k, address);
 	if (!pmd_k)
 		return -1;

 	pte_k = pte_offset_kernel(pmd_k, address);
 	if (!pte_present(*pte_k))
 		return -1;

 	return 0;
 }

 static int fault_in_kernel_space(unsigned long address)
 {
 	return address >= TASK_SIZE;
 }

 /*
  * 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)
 {
 	unsigned long vec;
 	struct task_struct *tsk;
 	struct mm_struct *mm;
 	struct vm_area_struct * vma;
 	int si_code;
 	int fault;
 	siginfo_t info;

 	tsk = current;
 	mm = tsk->mm;
 	si_code = SEGV_MAPERR;
 	vec = lookup_exception_vector();

 	/*
 	 * 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 (unlikely(fault_in_kernel_space(address))) {
 		if (vmalloc_fault(address) >= 0)
 			return;
 		if (notify_page_fault(regs, vec))
 			return;

 		goto bad_area_nosemaphore;
 	}

 	if (unlikely(notify_page_fault(regs, vec)))
 		return;

 	/* Only enable interrupts if they were on before the fault */
 	if ((regs->sr & SR_IMASK) != SR_IMASK)
 		local_irq_enable();

 	perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);

 	/*
 	 * If we're in an interrupt, have no user context or are running
 	 * in an atomic region then 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:
 	fault = handle_mm_fault(mm, vma, address, writeaccess ? FAULT_FLAG_WRITE : 0);
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
 		else if (fault & VM_FAULT_SIGBUS)
 			goto do_sigbus;
 		BUG();
 	}
 	if (fault & VM_FAULT_MAJOR) {
 		tsk->maj_flt++;
 		perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
 				     regs, address);
 	} else {
 		tsk->min_flt++;
 		perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
 				     regs, address);
 	}

 	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;

 	if (handle_trapped_io(regs, address))
 		return;
 /*
  * Oops. The kernel tried to access some bad page. We'll have to
  * terminate things with extreme prejudice.
  *
  */

 	bust_spinlocks(1);

 	if (oops_may_print()) {
 		unsigned long page;

 		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);
 		page = (unsigned long)get_TTB();
 		if (page) {
 			page = ((__typeof__(page) *)page)[address >> PGDIR_SHIFT];
 			printk(KERN_ALERT "*pde = %08lx\n", page);
 			if (page & _PAGE_PRESENT) {
 				page &= PAGE_MASK;
 				address &= 0x003ff000;
 				page = ((__typeof__(page) *)
 						__va(page))[address >>
 							    PAGE_SHIFT];
 				printk(KERN_ALERT "*pte = %08lx\n", page);
 			}
 		}
 	}

 	die("Oops", regs, writeaccess);
 	bust_spinlocks(0);
 	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_global_init(current)) {
 		yield();
 		down_read(&mm->mmap_sem);
 		goto survive;
 	}
 	printk("VM: killing process %s\n", tsk->comm);
 	if (user_mode(regs))
 		do_group_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;
 }

 /*
  * Called with interrupts disabled.
  */
 asmlinkage int __kprobes
 handle_tlbmiss(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;
 	int ret = 1;

 	/*
 	 * 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);
 	} else {
 		if (unlikely(address >= TASK_SIZE || !current->mm))
 			goto out;

 		pgd = pgd_offset(current->mm, address);
 	}

 	pud = pud_offset(pgd, address);
 	if (pud_none_or_clear_bad(pud))
 		goto out;
 	pmd = pmd_offset(pud, address);
 	if (pmd_none_or_clear_bad(pmd))
 		goto out;
 	pte = pte_offset_kernel(pmd, address);
 	entry = *pte;
 	if (unlikely(pte_none(entry) || pte_not_present(entry)))
 		goto out;
 	if (unlikely(writeaccess && !pte_write(entry)))
 		goto out;

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

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

 	set_pte(pte, entry);
 	update_mmu_cache(NULL, address, entry);

 	ret = 0;
 out:
 	return ret;
 }
	/*
	* Page fault handler for SH with an MMU.
	*
	* Copyright (C) 1999 Niibe Yutaka
	* Copyright (C) 2003 - 2009 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 <linux/perf_counter.h>
	#include <asm/io_trapped.h>
	#include <asm/system.h>
	#include <asm/mmu_context.h>
	#include <asm/tlbflush.h>

	static inline int notify_page_fault(struct pt_regs *regs, int trap)
	{
	int ret = 0;

	if (kprobes_built_in() && !user_mode(regs)) {
	preempt_disable();
	if (kprobe_running() && kprobe_fault_handler(regs, trap))
	ret = 1;
	preempt_enable();
	}

	return ret;
	}

	static inline pmd_t vmalloc_sync_one(pgd_t pgd, unsigned long address)
	{
	unsigned index = pgd_index(address);
	pgd_t *pgd_k;
	pud_t pud, pud_k;
	pmd_t pmd, pmd_k;

	pgd += index;
	pgd_k = init_mm.pgd + index;

	if (!pgd_present(*pgd_k))
	return NULL;

	pud = pud_offset(pgd, address);
	pud_k = pud_offset(pgd_k, address);
	if (!pud_present(*pud_k))
	return NULL;

	pmd = pmd_offset(pud, address);
	pmd_k = pmd_offset(pud_k, address);
	if (!pmd_present(*pmd_k))
	return NULL;

	if (!pmd_present(*pmd))
	set_pmd(pmd, *pmd_k);
	else {
	/*
	* The page tables are fully synchronised so there must
	* be another reason for the fault. Return NULL here to
	* signal that we have not taken care of the fault.
	*/
	BUG_ON(pmd_page(pmd) != pmd_page(pmd_k));
	return NULL;
	}

	return pmd_k;
	}

	/*
	* Handle a fault on the vmalloc or module mapping area
	*/
	static noinline int vmalloc_fault(unsigned long address)
	{
	pgd_t *pgd_k;
	pmd_t *pmd_k;
	pte_t *pte_k;

	/* Make sure we are in vmalloc area: */
	if (!(address >= VMALLOC_START && address < VMALLOC_END))
	return -1;

	/*
	* Synchronize this task's top level page-table
	* with the 'reference' page table.
	*
	* Do _not_ use "current" here. We might be inside
	* an interrupt in the middle of a task switch..
	*/
	pgd_k = get_TTB();
	pmd_k = vmalloc_sync_one(pgd_k, address);
	if (!pmd_k)
	return -1;

	pte_k = pte_offset_kernel(pmd_k, address);
	if (!pte_present(*pte_k))
	return -1;

	return 0;
	}

	static int fault_in_kernel_space(unsigned long address)
	{
	return address >= TASK_SIZE;
	}

	/*
	* 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)
	{
	unsigned long vec;
	struct task_struct *tsk;
	struct mm_struct *mm;
	struct vm_area_struct * vma;
	int si_code;
	int fault;
	siginfo_t info;

	tsk = current;
	mm = tsk->mm;
	si_code = SEGV_MAPERR;
	vec = lookup_exception_vector();

	/*
	* 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 (unlikely(fault_in_kernel_space(address))) {
	if (vmalloc_fault(address) >= 0)
	return;
	if (notify_page_fault(regs, vec))
	return;

	goto bad_area_nosemaphore;
	}

	if (unlikely(notify_page_fault(regs, vec)))
	return;

	/* Only enable interrupts if they were on before the fault */
	if ((regs->sr & SR_IMASK) != SR_IMASK)
	local_irq_enable();

	perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);

	/*
	* If we're in an interrupt, have no user context or are running
	* in an atomic region then 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:
	fault = handle_mm_fault(mm, vma, address, writeaccess ? FAULT_FLAG_WRITE : 0);
	if (unlikely(fault & VM_FAULT_ERROR)) {
	if (fault & VM_FAULT_OOM)
	goto out_of_memory;
	else if (fault & VM_FAULT_SIGBUS)
	goto do_sigbus;
	BUG();
	}
	if (fault & VM_FAULT_MAJOR) {
	tsk->maj_flt++;
	perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
	regs, address);
	} else {
	tsk->min_flt++;
	perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
	regs, address);
	}

	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;

	if (handle_trapped_io(regs, address))
	return;
	/*
	* Oops. The kernel tried to access some bad page. We'll have to
	* terminate things with extreme prejudice.
	*
	*/

	bust_spinlocks(1);

	if (oops_may_print()) {
	unsigned long page;

	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);
	page = (unsigned long)get_TTB();
	if (page) {
	page = ((__typeof__(page) *)page)[address >> PGDIR_SHIFT];
	printk(KERN_ALERT "*pde = %08lx\n", page);
	if (page & _PAGE_PRESENT) {
	page &= PAGE_MASK;
	address &= 0x003ff000;
	page = ((__typeof__(page) *)
	__va(page))[address >>
	PAGE_SHIFT];
	printk(KERN_ALERT "*pte = %08lx\n", page);
	}
	}
	}

	die("Oops", regs, writeaccess);
	bust_spinlocks(0);
	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_global_init(current)) {
	yield();
	down_read(&mm->mmap_sem);
	goto survive;
	}
	printk("VM: killing process %s\n", tsk->comm);
	if (user_mode(regs))
	do_group_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;
	}

	/*
	* Called with interrupts disabled.
	*/
	asmlinkage int __kprobes
	handle_tlbmiss(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;
	int ret = 1;

	/*
	* 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);
	} else {
	if (unlikely(address >= TASK_SIZE \|\| !current->mm))
	goto out;

	pgd = pgd_offset(current->mm, address);
	}

	pud = pud_offset(pgd, address);
	if (pud_none_or_clear_bad(pud))
	goto out;
	pmd = pmd_offset(pud, address);
	if (pmd_none_or_clear_bad(pmd))
	goto out;
	pte = pte_offset_kernel(pmd, address);
	entry = *pte;
	if (unlikely(pte_none(entry) \|\| pte_not_present(entry)))
	goto out;
	if (unlikely(writeaccess && !pte_write(entry)))
	goto out;

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

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

	set_pte(pte, entry);
	update_mmu_cache(NULL, address, entry);

	ret = 0;
	out:
	return ret;
	}