[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;

	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:
	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_ratelimit())
			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>
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;
5f97f7f9	67
9caebec7	68	if (notify_page_fault(regs, ecr))
5f97f7f9 HS	69	return;
	70
	71	address = sysreg_read(TLBEAR);
	72
	73	tsk = current;
	74	mm = tsk->mm;
	75
623b0355 HS	76	signr = SIGSEGV;
	77	code = SEGV_MAPERR;
	78
5f97f7f9 HS	79	/*
	80	* If we're in an interrupt or have no user context, we must
	81	* not take the fault...
	82	*/
	83	if (in_atomic() \|\| !mm \|\| regs->sr & SYSREG_BIT(GM))
	84	goto no_context;
	85
	86	local_irq_enable();
	87
	88	down_read(&mm->mmap_sem);
	89
	90	vma = find_vma(mm, address);
	91	if (!vma)
	92	goto bad_area;
	93	if (vma->vm_start <= address)
	94	goto good_area;
	95	if (!(vma->vm_flags & VM_GROWSDOWN))
	96	goto bad_area;
	97	if (expand_stack(vma, address))
	98	goto bad_area;
	99
	100	/*
	101	* Ok, we have a good vm_area for this memory access, so we
	102	* can handle it...
	103	*/
	104	good_area:
623b0355 HS	105	code = SEGV_ACCERR;
	106	writeaccess = 0;
	107
5f97f7f9 HS	108	switch (ecr) {
	109	case ECR_PROTECTION_X:
	110	case ECR_TLB_MISS_X:
	111	if (!(vma->vm_flags & VM_EXEC))
	112	goto bad_area;
	113	break;
	114	case ECR_PROTECTION_R:
	115	case ECR_TLB_MISS_R:
	116	if (!(vma->vm_flags & (VM_READ \| VM_WRITE \| VM_EXEC)))
	117	goto bad_area;
	118	break;
	119	case ECR_PROTECTION_W:
	120	case ECR_TLB_MISS_W:
	121	if (!(vma->vm_flags & VM_WRITE))
	122	goto bad_area;
	123	writeaccess = 1;
	124	break;
	125	default:
	126	panic("Unhandled case %lu in do_page_fault!", ecr);
	127	}
	128
	129	/*
	130	* If for any reason at all we couldn't handle the fault, make
	131	* sure we exit gracefully rather than endlessly redo the
	132	* fault.
	133	*/
	134	survive:
	135	switch (handle_mm_fault(mm, vma, address, writeaccess)) {
	136	case VM_FAULT_MINOR:
	137	tsk->min_flt++;
	138	break;
	139	case VM_FAULT_MAJOR:
	140	tsk->maj_flt++;
	141	break;
	142	case VM_FAULT_SIGBUS:
	143	goto do_sigbus;
	144	case VM_FAULT_OOM:
	145	goto out_of_memory;
	146	default:
	147	BUG();
	148	}
	149
	150	up_read(&mm->mmap_sem);
	151	return;
	152
	153	/*
	154	* Something tried to access memory that isn't in our memory
	155	* map. Fix it, but check if it's kernel or user first...
	156	*/
	157	bad_area:
5f97f7f9 HS	158	up_read(&mm->mmap_sem);
	159
	160	if (user_mode(regs)) {
126187f1	161	if (exception_trace && printk_ratelimit())
623b0355 HS	162	printk("%s%s[%d]: segfault at %08lx pc %08lx "
	163	"sp %08lx ecr %lu\n",
	164	is_init(tsk) ? KERN_EMERG : KERN_INFO,
	165	tsk->comm, tsk->pid, address, regs->pc,
	166	regs->sp, ecr);
	167	_exception(SIGSEGV, regs, code, address);
5f97f7f9 HS	168	return;
	169	}
	170
	171	no_context:
5f97f7f9 HS	172	/* Are we prepared to handle this kernel fault? */
	173	fixup = search_exception_tables(regs->pc);
	174	if (fixup) {
	175	regs->pc = fixup->fixup;
5f97f7f9 HS	176	return;
	177	}
	178
	179	/*
	180	* Oops. The kernel tried to access some bad page. We'll have
	181	* to terminate things with extreme prejudice.
	182	*/
	183	if (address < PAGE_SIZE)
	184	printk(KERN_ALERT
	185	"Unable to handle kernel NULL pointer dereference");
	186	else
	187	printk(KERN_ALERT
	188	"Unable to handle kernel paging request");
	189	printk(" at virtual address %08lx\n", address);
5f97f7f9 HS	190
	191	page = sysreg_read(PTBR);
	192	printk(KERN_ALERT "ptbr = %08lx", page);
	193	if (page) {
	194	page = ((unsigned long *)page)[address >> 22];
	195	printk(" pgd = %08lx", page);
	196	if (page & _PAGE_PRESENT) {
	197	page &= PAGE_MASK;
	198	address &= 0x003ff000;
	199	page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT];
623b0355	200	printk(" pte = %08lx", page);
5f97f7f9 HS	201	}
5f97f7f9 HS	202	}
623b0355 HS	203	printk("\n");
	204	die("Kernel access of bad area", regs, signr);
	205	return;
5f97f7f9 HS	206
	207	/*
	208	* We ran out of memory, or some other thing happened to us
	209	* that made us unable to handle the page fault gracefully.
	210	*/
	211	out_of_memory:
5f97f7f9	212	up_read(&mm->mmap_sem);
623b0355	213	if (is_init(current)) {
5f97f7f9 HS	214	yield();
	215	down_read(&mm->mmap_sem);
	216	goto survive;
	217	}
	218	printk("VM: Killing process %s\n", tsk->comm);
	219	if (user_mode(regs))
	220	do_exit(SIGKILL);
	221	goto no_context;
	222
	223	do_sigbus:
	224	up_read(&mm->mmap_sem);
	225
5f97f7f9	226	/* Kernel mode? Handle exceptions or die */
623b0355 HS	227	signr = SIGBUS;
623b0355 HS	228	code = BUS_ADRERR;
5f97f7f9 HS	229	if (!user_mode(regs))
5f97f7f9 HS	230	goto no_context;
623b0355 HS	231
	232	if (exception_trace)
	233	printk("%s%s[%d]: bus error at %08lx pc %08lx "
	234	"sp %08lx ecr %lu\n",
	235	is_init(tsk) ? KERN_EMERG : KERN_INFO,
	236	tsk->comm, tsk->pid, address, regs->pc,
	237	regs->sp, ecr);
	238
	239	_exception(SIGBUS, regs, BUS_ADRERR, address);
5f97f7f9 HS	240	}
	241
	242	asmlinkage void do_bus_error(unsigned long addr, int write_access,
	243	struct pt_regs *regs)
	244	{
	245	printk(KERN_ALERT
	246	"Bus error at physical address 0x%08lx (%s access)\n",
	247	addr, write_access ? "write" : "read");
	248	printk(KERN_INFO "DTLB dump:\n");
	249	dump_dtlb();
623b0355	250	die("Bus Error", regs, SIGKILL);
5f97f7f9 HS	251	}
	252
	253	/*
	254	* This functionality is currently not possible to implement because
	255	* we're using segmentation to ensure a fixed mapping of the kernel
	256	* virtual address space.
	257	*
	258	* It would be possible to implement this, but it would require us to
	259	* disable segmentation at startup and load the kernel mappings into
	260	* the TLB like any other pages. There will be lots of trickery to
	261	* avoid recursive invocation of the TLB miss handler, though...
	262	*/
	263	#ifdef CONFIG_DEBUG_PAGEALLOC
	264	void kernel_map_pages(struct page *page, int numpages, int enable)
	265	{
	266
	267	}
	268	EXPORT_SYMBOL(kernel_map_pages);
	269	#endif