arch/avr32/mm/fault.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (C) 2004-2006 Atmel Corporation
  *
  * Based on linux/arch/sh/mm/fault.c:
  *   Copyright (C) 1999  Niibe Yutaka
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */

 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/pagemap.h>
 #include <linux/kdebug.h>
 #include <linux/kprobes.h>

 #include <asm/mmu_context.h>
 #include <asm/sysreg.h>
 #include <asm/tlb.h>
 #include <asm/uaccess.h>

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

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

 	return ret;
 }
 #else
 static inline int notify_page_fault(struct pt_regs *regs, int trap)
 {
 	return 0;
 }
 #endif

 int exception_trace = 1;

 /*
  * This routine handles page faults. It determines the address and the
  * problem, and then passes it off to one of the appropriate routines.
  *
  * ecr is the Exception Cause Register. Possible values are:
  *   6:  Protection fault (instruction access)
  *   15: Protection fault (read access)
  *   16: Protection fault (write access)
  *   20: Page not found (instruction access)
  *   24: Page not found (read access)
  *   28: Page not found (write access)
  */
 asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
 {
 	struct task_struct *tsk;
 	struct mm_struct *mm;
 	struct vm_area_struct *vma;
 	const struct exception_table_entry *fixup;
 	unsigned long address;
 	unsigned long page;
 	int writeaccess;
 	long signr;
 	int code;
 	int fault;

 	if (notify_page_fault(regs, ecr))
 		return;

 	address = sysreg_read(TLBEAR);

 	tsk = current;
 	mm = tsk->mm;

 	signr = SIGSEGV;
 	code = SEGV_MAPERR;

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

 	local_irq_enable();

 	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:
 	code = SEGV_ACCERR;
 	writeaccess = 0;

 	switch (ecr) {
 	case ECR_PROTECTION_X:
 	case ECR_TLB_MISS_X:
 		if (!(vma->vm_flags & VM_EXEC))
 			goto bad_area;
 		break;
 	case ECR_PROTECTION_R:
 	case ECR_TLB_MISS_R:
 		if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
 			goto bad_area;
 		break;
 	case ECR_PROTECTION_W:
 	case ECR_TLB_MISS_W:
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;
 		writeaccess = 1;
 		break;
 	default:
 		panic("Unhandled case %lu in do_page_fault!", ecr);
 	}

 	/*
 	 * 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);
 	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++;
 	else
 		tsk->min_flt++;

 	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);

 	if (user_mode(regs)) {
 		if (exception_trace && printk_ratelimit())
 			printk("%s%s[%d]: segfault at %08lx pc %08lx "
 			       "sp %08lx ecr %lu\n",
 			       is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
 			       tsk->comm, tsk->pid, address, regs->pc,
 			       regs->sp, ecr);
 		_exception(SIGSEGV, regs, code, address);
 		return;
 	}

 no_context:
 	/* Are we prepared to handle this kernel fault? */
 	fixup = search_exception_tables(regs->pc);
 	if (fixup) {
 		regs->pc = fixup->fixup;
 		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);

 	page = sysreg_read(PTBR);
 	printk(KERN_ALERT "ptbr = %08lx", page);
 	if (page) {
 		page = ((unsigned long *)page)[address >> 22];
 		printk(" pgd = %08lx", page);
 		if (page & _PAGE_PRESENT) {
 			page &= PAGE_MASK;
 			address &= 0x003ff000;
 			page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT];
 			printk(" pte = %08lx", page);
 		}
 	}
 	printk("\n");
 	die("Kernel access of bad area", regs, signr);
 	return;

 	/*
 	 * 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);

 	/* Kernel mode? Handle exceptions or die */
 	signr = SIGBUS;
 	code = BUS_ADRERR;
 	if (!user_mode(regs))
 		goto no_context;

 	if (exception_trace)
 		printk("%s%s[%d]: bus error at %08lx pc %08lx "
 		       "sp %08lx ecr %lu\n",
 		       is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
 		       tsk->comm, tsk->pid, address, regs->pc,
 		       regs->sp, ecr);

 	_exception(SIGBUS, regs, BUS_ADRERR, address);
 }

 asmlinkage void do_bus_error(unsigned long addr, int write_access,
 			     struct pt_regs *regs)
 {
 	printk(KERN_ALERT
 	       "Bus error at physical address 0x%08lx (%s access)\n",
 	       addr, write_access ? "write" : "read");
 	printk(KERN_INFO "DTLB dump:\n");
 	dump_dtlb();
 	die("Bus Error", regs, SIGKILL);
 }

 /*
  * This functionality is currently not possible to implement because
  * we're using segmentation to ensure a fixed mapping of the kernel
  * virtual address space.
  *
  * It would be possible to implement this, but it would require us to
  * disable segmentation at startup and load the kernel mappings into
  * the TLB like any other pages. There will be lots of trickery to
  * avoid recursive invocation of the TLB miss handler, though...
  */
 #ifdef CONFIG_DEBUG_PAGEALLOC
 void kernel_map_pages(struct page *page, int numpages, int enable)
 {

 }
 EXPORT_SYMBOL(kernel_map_pages);
 #endif
	/*
	* Copyright (C) 2004-2006 Atmel Corporation
	*
	* Based on linux/arch/sh/mm/fault.c:
	* Copyright (C) 1999 Niibe Yutaka
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/pagemap.h>
	#include <linux/kdebug.h>
	#include <linux/kprobes.h>

	#include <asm/mmu_context.h>
	#include <asm/sysreg.h>
	#include <asm/tlb.h>
	#include <asm/uaccess.h>

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

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

	return ret;
	}
	#else
	static inline int notify_page_fault(struct pt_regs *regs, int trap)
	{
	return 0;
	}
	#endif

	int exception_trace = 1;

	/*
	* This routine handles page faults. It determines the address and the
	* problem, and then passes it off to one of the appropriate routines.
	*
	* ecr is the Exception Cause Register. Possible values are:
	* 6: Protection fault (instruction access)
	* 15: Protection fault (read access)
	* 16: Protection fault (write access)
	* 20: Page not found (instruction access)
	* 24: Page not found (read access)
	* 28: Page not found (write access)
	*/
	asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
	{
	struct task_struct *tsk;
	struct mm_struct *mm;
	struct vm_area_struct *vma;
	const struct exception_table_entry *fixup;
	unsigned long address;
	unsigned long page;
	int writeaccess;
	long signr;
	int code;
	int fault;

	if (notify_page_fault(regs, ecr))
	return;

	address = sysreg_read(TLBEAR);

	tsk = current;
	mm = tsk->mm;

	signr = SIGSEGV;
	code = SEGV_MAPERR;

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

	local_irq_enable();

	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:
	code = SEGV_ACCERR;
	writeaccess = 0;

	switch (ecr) {
	case ECR_PROTECTION_X:
	case ECR_TLB_MISS_X:
	if (!(vma->vm_flags & VM_EXEC))
	goto bad_area;
	break;
	case ECR_PROTECTION_R:
	case ECR_TLB_MISS_R:
	if (!(vma->vm_flags & (VM_READ \| VM_WRITE \| VM_EXEC)))
	goto bad_area;
	break;
	case ECR_PROTECTION_W:
	case ECR_TLB_MISS_W:
	if (!(vma->vm_flags & VM_WRITE))
	goto bad_area;
	writeaccess = 1;
	break;
	default:
	panic("Unhandled case %lu in do_page_fault!", ecr);
	}

	/*
	* 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);
	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++;
	else
	tsk->min_flt++;

	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);

	if (user_mode(regs)) {
	if (exception_trace && printk_ratelimit())
	printk("%s%s[%d]: segfault at %08lx pc %08lx "
	"sp %08lx ecr %lu\n",
	is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
	tsk->comm, tsk->pid, address, regs->pc,
	regs->sp, ecr);
	_exception(SIGSEGV, regs, code, address);
	return;
	}

	no_context:
	/* Are we prepared to handle this kernel fault? */
	fixup = search_exception_tables(regs->pc);
	if (fixup) {
	regs->pc = fixup->fixup;
	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);

	page = sysreg_read(PTBR);
	printk(KERN_ALERT "ptbr = %08lx", page);
	if (page) {
	page = ((unsigned long *)page)[address >> 22];
	printk(" pgd = %08lx", page);
	if (page & _PAGE_PRESENT) {
	page &= PAGE_MASK;
	address &= 0x003ff000;
	page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT];
	printk(" pte = %08lx", page);
	}
	}
	printk("\n");
	die("Kernel access of bad area", regs, signr);
	return;

	/*
	* 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);

	/* Kernel mode? Handle exceptions or die */
	signr = SIGBUS;
	code = BUS_ADRERR;
	if (!user_mode(regs))
	goto no_context;

	if (exception_trace)
	printk("%s%s[%d]: bus error at %08lx pc %08lx "
	"sp %08lx ecr %lu\n",
	is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
	tsk->comm, tsk->pid, address, regs->pc,
	regs->sp, ecr);

	_exception(SIGBUS, regs, BUS_ADRERR, address);
	}

	asmlinkage void do_bus_error(unsigned long addr, int write_access,
	struct pt_regs *regs)
	{
	printk(KERN_ALERT
	"Bus error at physical address 0x%08lx (%s access)\n",
	addr, write_access ? "write" : "read");
	printk(KERN_INFO "DTLB dump:\n");
	dump_dtlb();
	die("Bus Error", regs, SIGKILL);
	}

	/*
	* This functionality is currently not possible to implement because
	* we're using segmentation to ensure a fixed mapping of the kernel
	* virtual address space.
	*
	* It would be possible to implement this, but it would require us to
	* disable segmentation at startup and load the kernel mappings into
	* the TLB like any other pages. There will be lots of trickery to
	* avoid recursive invocation of the TLB miss handler, though...
	*/
	#ifdef CONFIG_DEBUG_PAGEALLOC
	void kernel_map_pages(struct page *page, int numpages, int enable)
	{

	}
	EXPORT_SYMBOL(kernel_map_pages);
	#endif