[net-next-2.6.git] / arch / avr32 / mm / fault.c

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

#ifdef CONFIG_KPROBES
ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);

/* Hook to register for page fault notifications */
int register_page_fault_notifier(struct notifier_block *nb)
{
	return atomic_notifier_chain_register(&notify_page_fault_chain, nb);
}

int unregister_page_fault_notifier(struct notifier_block *nb)
{
	return atomic_notifier_chain_unregister(&notify_page_fault_chain, nb);
}

static inline int notify_page_fault(enum die_val val, struct pt_regs *regs,
				    int trap, int sig)
{
	struct die_args args = {
		.regs = regs,
		.trapnr = trap,
	};
	return atomic_notifier_call_chain(&notify_page_fault_chain, val, &args);
}
#else
static inline int notify_page_fault(enum die_val val, struct pt_regs *regs,
				    int trap, int sig)
{
	return NOTIFY_DONE;
}
#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;

	if (notify_page_fault(DIE_PAGE_FAULT, regs,
			      ecr, SIGSEGV) == NOTIFY_STOP)
		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:
	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);

	if (user_mode(regs)) {
		if (exception_trace)
			printk("%s%s[%d]: segfault at %08lx pc %08lx "
			       "sp %08lx ecr %lu\n",
			       is_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_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);

	/* 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_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
Commit	Line	Data
5f97f7f9 HS	1	/*
	2	* Copyright (C) 2004-2006 Atmel Corporation
	3	*
	4	* Based on linux/arch/sh/mm/fault.c:
	5	* Copyright (C) 1999 Niibe Yutaka
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*/
	11
	12	#include <linux/mm.h>
	13	#include <linux/module.h>
	14	#include <linux/pagemap.h>
	15
1eeb66a1	16	#include <linux/kdebug.h>
5f97f7f9 HS	17	#include <asm/mmu_context.h>
5f97f7f9 HS	18	#include <asm/sysreg.h>
5f97f7f9	19	#include <asm/tlb.h>
623b0355	20	#include <asm/uaccess.h>
5f97f7f9 HS	21
	22	#ifdef CONFIG_KPROBES
	23	ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
	24
	25	/* Hook to register for page fault notifications */
	26	int register_page_fault_notifier(struct notifier_block *nb)
	27	{
	28	return atomic_notifier_chain_register(&notify_page_fault_chain, nb);
	29	}
	30
	31	int unregister_page_fault_notifier(struct notifier_block *nb)
	32	{
	33	return atomic_notifier_chain_unregister(&notify_page_fault_chain, nb);
	34	}
	35
	36	static inline int notify_page_fault(enum die_val val, struct pt_regs *regs,
	37	int trap, int sig)
	38	{
	39	struct die_args args = {
	40	.regs = regs,
	41	.trapnr = trap,
	42	};
	43	return atomic_notifier_call_chain(&notify_page_fault_chain, val, &args);
	44	}
	45	#else
	46	static inline int notify_page_fault(enum die_val val, struct pt_regs *regs,
	47	int trap, int sig)
	48	{
	49	return NOTIFY_DONE;
	50	}
	51	#endif
	52
623b0355 HS	53	int exception_trace = 1;
623b0355 HS	54
5f97f7f9 HS	55	/*
	56	* This routine handles page faults. It determines the address and the
	57	* problem, and then passes it off to one of the appropriate routines.
	58	*
	59	* ecr is the Exception Cause Register. Possible values are:
5f97f7f9	60	* 6: Protection fault (instruction access)
623b0355 HS	61	* 15: Protection fault (read access)
	62	* 16: Protection fault (write access)
	63	* 20: Page not found (instruction access)
	64	* 24: Page not found (read access)
	65	* 28: Page not found (write access)
5f97f7f9 HS	66	*/
	67	asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
	68	{
	69	struct task_struct *tsk;
	70	struct mm_struct *mm;
	71	struct vm_area_struct *vma;
	72	const struct exception_table_entry *fixup;
	73	unsigned long address;
	74	unsigned long page;
623b0355 HS	75	int writeaccess;
	76	long signr;
	77	int code;
5f97f7f9 HS	78
	79	if (notify_page_fault(DIE_PAGE_FAULT, regs,
	80	ecr, SIGSEGV) == NOTIFY_STOP)
	81	return;
	82
	83	address = sysreg_read(TLBEAR);
	84
	85	tsk = current;
	86	mm = tsk->mm;
	87
623b0355 HS	88	signr = SIGSEGV;
	89	code = SEGV_MAPERR;
	90
5f97f7f9 HS	91	/*
	92	* If we're in an interrupt or have no user context, we must
	93	* not take the fault...
	94	*/
	95	if (in_atomic() \|\| !mm \|\| regs->sr & SYSREG_BIT(GM))
	96	goto no_context;
	97
	98	local_irq_enable();
	99
	100	down_read(&mm->mmap_sem);
	101
	102	vma = find_vma(mm, address);
	103	if (!vma)
	104	goto bad_area;
	105	if (vma->vm_start <= address)
	106	goto good_area;
	107	if (!(vma->vm_flags & VM_GROWSDOWN))
	108	goto bad_area;
	109	if (expand_stack(vma, address))
	110	goto bad_area;
	111
	112	/*
	113	* Ok, we have a good vm_area for this memory access, so we
	114	* can handle it...
	115	*/
	116	good_area:
623b0355 HS	117	code = SEGV_ACCERR;
	118	writeaccess = 0;
	119
5f97f7f9 HS	120	switch (ecr) {
	121	case ECR_PROTECTION_X:
	122	case ECR_TLB_MISS_X:
	123	if (!(vma->vm_flags & VM_EXEC))
	124	goto bad_area;
	125	break;
	126	case ECR_PROTECTION_R:
	127	case ECR_TLB_MISS_R:
	128	if (!(vma->vm_flags & (VM_READ \| VM_WRITE \| VM_EXEC)))
	129	goto bad_area;
	130	break;
	131	case ECR_PROTECTION_W:
	132	case ECR_TLB_MISS_W:
	133	if (!(vma->vm_flags & VM_WRITE))
	134	goto bad_area;
	135	writeaccess = 1;
	136	break;
	137	default:
	138	panic("Unhandled case %lu in do_page_fault!", ecr);
	139	}
	140
	141	/*
	142	* If for any reason at all we couldn't handle the fault, make
	143	* sure we exit gracefully rather than endlessly redo the
	144	* fault.
	145	*/
	146	survive:
	147	switch (handle_mm_fault(mm, vma, address, writeaccess)) {
	148	case VM_FAULT_MINOR:
	149	tsk->min_flt++;
	150	break;
	151	case VM_FAULT_MAJOR:
	152	tsk->maj_flt++;
	153	break;
	154	case VM_FAULT_SIGBUS:
	155	goto do_sigbus;
	156	case VM_FAULT_OOM:
	157	goto out_of_memory;
	158	default:
	159	BUG();
	160	}
	161
	162	up_read(&mm->mmap_sem);
	163	return;
	164
	165	/*
	166	* Something tried to access memory that isn't in our memory
	167	* map. Fix it, but check if it's kernel or user first...
	168	*/
	169	bad_area:
5f97f7f9 HS	170	up_read(&mm->mmap_sem);
	171
	172	if (user_mode(regs)) {
623b0355 HS	173	if (exception_trace)
	174	printk("%s%s[%d]: segfault at %08lx pc %08lx "
	175	"sp %08lx ecr %lu\n",
	176	is_init(tsk) ? KERN_EMERG : KERN_INFO,
	177	tsk->comm, tsk->pid, address, regs->pc,
	178	regs->sp, ecr);
	179	_exception(SIGSEGV, regs, code, address);
5f97f7f9 HS	180	return;
	181	}
	182
	183	no_context:
5f97f7f9 HS	184	/* Are we prepared to handle this kernel fault? */
	185	fixup = search_exception_tables(regs->pc);
	186	if (fixup) {
	187	regs->pc = fixup->fixup;
5f97f7f9 HS	188	return;
	189	}
	190
	191	/*
	192	* Oops. The kernel tried to access some bad page. We'll have
	193	* to terminate things with extreme prejudice.
	194	*/
	195	if (address < PAGE_SIZE)
	196	printk(KERN_ALERT
	197	"Unable to handle kernel NULL pointer dereference");
	198	else
	199	printk(KERN_ALERT
	200	"Unable to handle kernel paging request");
	201	printk(" at virtual address %08lx\n", address);
5f97f7f9 HS	202
	203	page = sysreg_read(PTBR);
	204	printk(KERN_ALERT "ptbr = %08lx", page);
	205	if (page) {
	206	page = ((unsigned long *)page)[address >> 22];
	207	printk(" pgd = %08lx", page);
	208	if (page & _PAGE_PRESENT) {
	209	page &= PAGE_MASK;
	210	address &= 0x003ff000;
	211	page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT];
623b0355	212	printk(" pte = %08lx", page);
5f97f7f9 HS	213	}
5f97f7f9 HS	214	}
623b0355 HS	215	printk("\n");
	216	die("Kernel access of bad area", regs, signr);
	217	return;
5f97f7f9 HS	218
	219	/*
	220	* We ran out of memory, or some other thing happened to us
	221	* that made us unable to handle the page fault gracefully.
	222	*/
	223	out_of_memory:
5f97f7f9	224	up_read(&mm->mmap_sem);
623b0355	225	if (is_init(current)) {
5f97f7f9 HS	226	yield();
	227	down_read(&mm->mmap_sem);
	228	goto survive;
	229	}
	230	printk("VM: Killing process %s\n", tsk->comm);
	231	if (user_mode(regs))
	232	do_exit(SIGKILL);
	233	goto no_context;
	234
	235	do_sigbus:
	236	up_read(&mm->mmap_sem);
	237
5f97f7f9	238	/* Kernel mode? Handle exceptions or die */
623b0355 HS	239	signr = SIGBUS;
623b0355 HS	240	code = BUS_ADRERR;
5f97f7f9 HS	241	if (!user_mode(regs))
5f97f7f9 HS	242	goto no_context;
623b0355 HS	243
	244	if (exception_trace)
	245	printk("%s%s[%d]: bus error at %08lx pc %08lx "
	246	"sp %08lx ecr %lu\n",
	247	is_init(tsk) ? KERN_EMERG : KERN_INFO,
	248	tsk->comm, tsk->pid, address, regs->pc,
	249	regs->sp, ecr);
	250
	251	_exception(SIGBUS, regs, BUS_ADRERR, address);
5f97f7f9 HS	252	}
	253
	254	asmlinkage void do_bus_error(unsigned long addr, int write_access,
	255	struct pt_regs *regs)
	256	{
	257	printk(KERN_ALERT
	258	"Bus error at physical address 0x%08lx (%s access)\n",
	259	addr, write_access ? "write" : "read");
	260	printk(KERN_INFO "DTLB dump:\n");
	261	dump_dtlb();
623b0355	262	die("Bus Error", regs, SIGKILL);
5f97f7f9 HS	263	}
	264
	265	/*
	266	* This functionality is currently not possible to implement because
	267	* we're using segmentation to ensure a fixed mapping of the kernel
	268	* virtual address space.
	269	*
	270	* It would be possible to implement this, but it would require us to
	271	* disable segmentation at startup and load the kernel mappings into
	272	* the TLB like any other pages. There will be lots of trickery to
	273	* avoid recursive invocation of the TLB miss handler, though...
	274	*/
	275	#ifdef CONFIG_DEBUG_PAGEALLOC
	276	void kernel_map_pages(struct page *page, int numpages, int enable)
	277	{
	278
	279	}
	280	EXPORT_SYMBOL(kernel_map_pages);
	281	#endif