[linux-2.6-block.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 <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 ? 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++;
	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 (address >= TASK_SIZE)
		page = (unsigned long)swapper_pg_dir;
	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);
}
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>
1eeb66a1	15	#include <linux/kdebug.h>
9caebec7 CH	16	#include <linux/kprobes.h>
9caebec7 CH	17
5f97f7f9 HS	18	#include <asm/mmu_context.h>
5f97f7f9 HS	19	#include <asm/sysreg.h>
5f97f7f9	20	#include <asm/tlb.h>
623b0355	21	#include <asm/uaccess.h>
5f97f7f9 HS	22
5f97f7f9 HS	23	#ifdef CONFIG_KPROBES
9caebec7	24	static inline int notify_page_fault(struct pt_regs *regs, int trap)
5f97f7f9	25	{
9caebec7	26	int ret = 0;
5f97f7f9	27
9caebec7 CH	28	if (!user_mode(regs)) {
	29	if (kprobe_running() && kprobe_fault_handler(regs, trap))
	30	ret = 1;
	31	}
5f97f7f9	32
9caebec7	33	return ret;
5f97f7f9 HS	34	}
5f97f7f9 HS	35	#else
9caebec7	36	static inline int notify_page_fault(struct pt_regs *regs, int trap)
5f97f7f9	37	{
9caebec7	38	return 0;
5f97f7f9 HS	39	}
	40	#endif
	41
623b0355 HS	42	int exception_trace = 1;
623b0355 HS	43
5f97f7f9 HS	44	/*
	45	* This routine handles page faults. It determines the address and the
	46	* problem, and then passes it off to one of the appropriate routines.
	47	*
	48	* ecr is the Exception Cause Register. Possible values are:
5f97f7f9	49	* 6: Protection fault (instruction access)
623b0355 HS	50	* 15: Protection fault (read access)
	51	* 16: Protection fault (write access)
	52	* 20: Page not found (instruction access)
	53	* 24: Page not found (read access)
	54	* 28: Page not found (write access)
5f97f7f9 HS	55	*/
	56	asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
	57	{
	58	struct task_struct *tsk;
	59	struct mm_struct *mm;
	60	struct vm_area_struct *vma;
	61	const struct exception_table_entry *fixup;
	62	unsigned long address;
	63	unsigned long page;
623b0355 HS	64	int writeaccess;
	65	long signr;
	66	int code;
83c54070	67	int fault;
5f97f7f9	68
9caebec7	69	if (notify_page_fault(regs, ecr))
5f97f7f9 HS	70	return;
	71
	72	address = sysreg_read(TLBEAR);
	73
	74	tsk = current;
	75	mm = tsk->mm;
	76
623b0355 HS	77	signr = SIGSEGV;
	78	code = SEGV_MAPERR;
	79
5f97f7f9 HS	80	/*
	81	* If we're in an interrupt or have no user context, we must
	82	* not take the fault...
	83	*/
	84	if (in_atomic() \|\| !mm \|\| regs->sr & SYSREG_BIT(GM))
	85	goto no_context;
	86
	87	local_irq_enable();
	88
	89	down_read(&mm->mmap_sem);
	90
	91	vma = find_vma(mm, address);
	92	if (!vma)
	93	goto bad_area;
	94	if (vma->vm_start <= address)
	95	goto good_area;
	96	if (!(vma->vm_flags & VM_GROWSDOWN))
	97	goto bad_area;
	98	if (expand_stack(vma, address))
	99	goto bad_area;
	100
	101	/*
	102	* Ok, we have a good vm_area for this memory access, so we
	103	* can handle it...
	104	*/
	105	good_area:
623b0355 HS	106	code = SEGV_ACCERR;
	107	writeaccess = 0;
	108
5f97f7f9 HS	109	switch (ecr) {
	110	case ECR_PROTECTION_X:
	111	case ECR_TLB_MISS_X:
	112	if (!(vma->vm_flags & VM_EXEC))
	113	goto bad_area;
	114	break;
	115	case ECR_PROTECTION_R:
	116	case ECR_TLB_MISS_R:
	117	if (!(vma->vm_flags & (VM_READ \| VM_WRITE \| VM_EXEC)))
	118	goto bad_area;
	119	break;
	120	case ECR_PROTECTION_W:
	121	case ECR_TLB_MISS_W:
	122	if (!(vma->vm_flags & VM_WRITE))
	123	goto bad_area;
	124	writeaccess = 1;
	125	break;
	126	default:
	127	panic("Unhandled case %lu in do_page_fault!", ecr);
	128	}
	129
	130	/*
	131	* If for any reason at all we couldn't handle the fault, make
	132	* sure we exit gracefully rather than endlessly redo the
	133	* fault.
	134	*/
	135	survive:
d06063cc	136	fault = handle_mm_fault(mm, vma, address, writeaccess ? FAULT_FLAG_WRITE : 0);
83c54070 NP	137	if (unlikely(fault & VM_FAULT_ERROR)) {
	138	if (fault & VM_FAULT_OOM)
	139	goto out_of_memory;
	140	else if (fault & VM_FAULT_SIGBUS)
	141	goto do_sigbus;
5f97f7f9 HS	142	BUG();
5f97f7f9 HS	143	}
83c54070 NP	144	if (fault & VM_FAULT_MAJOR)
	145	tsk->maj_flt++;
	146	else
	147	tsk->min_flt++;
5f97f7f9 HS	148
	149	up_read(&mm->mmap_sem);
	150	return;
	151
	152	/*
	153	* Something tried to access memory that isn't in our memory
	154	* map. Fix it, but check if it's kernel or user first...
	155	*/
	156	bad_area:
5f97f7f9 HS	157	up_read(&mm->mmap_sem);
	158
	159	if (user_mode(regs)) {
126187f1	160	if (exception_trace && printk_ratelimit())
623b0355 HS	161	printk("%s%s[%d]: segfault at %08lx pc %08lx "
623b0355 HS	162	"sp %08lx ecr %lu\n",
b460cbc5	163	is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
623b0355 HS	164	tsk->comm, tsk->pid, address, regs->pc,
	165	regs->sp, ecr);
	166	_exception(SIGSEGV, regs, code, address);
5f97f7f9 HS	167	return;
	168	}
	169
	170	no_context:
5f97f7f9 HS	171	/* Are we prepared to handle this kernel fault? */
	172	fixup = search_exception_tables(regs->pc);
	173	if (fixup) {
	174	regs->pc = fixup->fixup;
5f97f7f9 HS	175	return;
	176	}
	177
	178	/*
	179	* Oops. The kernel tried to access some bad page. We'll have
	180	* to terminate things with extreme prejudice.
	181	*/
	182	if (address < PAGE_SIZE)
	183	printk(KERN_ALERT
	184	"Unable to handle kernel NULL pointer dereference");
	185	else
	186	printk(KERN_ALERT
	187	"Unable to handle kernel paging request");
	188	printk(" at virtual address %08lx\n", address);
5f97f7f9 HS	189
	190	page = sysreg_read(PTBR);
	191	printk(KERN_ALERT "ptbr = %08lx", page);
32019828 HS	192	if (address >= TASK_SIZE)
32019828 HS	193	page = (unsigned long)swapper_pg_dir;
5f97f7f9 HS	194	if (page) {
	195	page = ((unsigned long *)page)[address >> 22];
	196	printk(" pgd = %08lx", page);
	197	if (page & _PAGE_PRESENT) {
	198	page &= PAGE_MASK;
	199	address &= 0x003ff000;
	200	page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT];
623b0355	201	printk(" pte = %08lx", page);
5f97f7f9 HS	202	}
5f97f7f9 HS	203	}
623b0355 HS	204	printk("\n");
	205	die("Kernel access of bad area", regs, signr);
	206	return;
5f97f7f9 HS	207
	208	/*
	209	* We ran out of memory, or some other thing happened to us
	210	* that made us unable to handle the page fault gracefully.
	211	*/
	212	out_of_memory:
5f97f7f9	213	up_read(&mm->mmap_sem);
b460cbc5	214	if (is_global_init(current)) {
5f97f7f9 HS	215	yield();
	216	down_read(&mm->mmap_sem);
	217	goto survive;
	218	}
	219	printk("VM: Killing process %s\n", tsk->comm);
	220	if (user_mode(regs))
dcca2bde	221	do_group_exit(SIGKILL);
5f97f7f9 HS	222	goto no_context;
	223
	224	do_sigbus:
	225	up_read(&mm->mmap_sem);
	226
5f97f7f9	227	/* Kernel mode? Handle exceptions or die */
623b0355 HS	228	signr = SIGBUS;
623b0355 HS	229	code = BUS_ADRERR;
5f97f7f9 HS	230	if (!user_mode(regs))
5f97f7f9 HS	231	goto no_context;
623b0355 HS	232
	233	if (exception_trace)
	234	printk("%s%s[%d]: bus error at %08lx pc %08lx "
	235	"sp %08lx ecr %lu\n",
b460cbc5	236	is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
623b0355 HS	237	tsk->comm, tsk->pid, address, regs->pc,
	238	regs->sp, ecr);
	239
	240	_exception(SIGBUS, regs, BUS_ADRERR, address);
5f97f7f9 HS	241	}
	242
	243	asmlinkage void do_bus_error(unsigned long addr, int write_access,
	244	struct pt_regs *regs)
	245	{
	246	printk(KERN_ALERT
	247	"Bus error at physical address 0x%08lx (%s access)\n",
	248	addr, write_access ? "write" : "read");
	249	printk(KERN_INFO "DTLB dump:\n");
	250	dump_dtlb();
623b0355	251	die("Bus Error", regs, SIGKILL);
5f97f7f9	252	}