[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / arm / mm / fault.c

/*
 *  linux/arch/arm/mm/fault.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 *  Modifications for ARM processor (c) 1995-2004 Russell King
 *
 * 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/module.h>
#include <linux/signal.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/kprobes.h>

#include <asm/system.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/uaccess.h>

#include "fault.h"


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

	if (!user_mode(regs)) {
		/* kprobe_running() needs smp_processor_id() */
		preempt_disable();
		if (kprobe_running() && kprobe_fault_handler(regs, fsr))
			ret = 1;
		preempt_enable();
	}

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

/*
 * This is useful to dump out the page tables associated with
 * 'addr' in mm 'mm'.
 */
void show_pte(struct mm_struct *mm, unsigned long addr)
{
	pgd_t *pgd;

	if (!mm)
		mm = &init_mm;

	printk(KERN_ALERT "pgd = %p\n", mm->pgd);
	pgd = pgd_offset(mm, addr);
	printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));

	do {
		pmd_t *pmd;
		pte_t *pte;

		if (pgd_none(*pgd))
			break;

		if (pgd_bad(*pgd)) {
			printk("(bad)");
			break;
		}

		pmd = pmd_offset(pgd, addr);
#if PTRS_PER_PMD != 1
		printk(", *pmd=%08lx", pmd_val(*pmd));
#endif

		if (pmd_none(*pmd))
			break;

		if (pmd_bad(*pmd)) {
			printk("(bad)");
			break;
		}

#ifndef CONFIG_HIGHMEM
		/* We must not map this if we have highmem enabled */
		pte = pte_offset_map(pmd, addr);
		printk(", *pte=%08lx", pte_val(*pte));
		printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE]));
		pte_unmap(pte);
#endif
	} while(0);

	printk("\n");
}

/*
 * Oops.  The kernel tried to access some page that wasn't present.
 */
static void
__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
		  struct pt_regs *regs)
{
	/*
	 * Are we prepared to handle this kernel fault?
	 */
	if (fixup_exception(regs))
		return;

	/*
	 * No handler, we'll have to terminate things with extreme prejudice.
	 */
	bust_spinlocks(1);
	printk(KERN_ALERT
		"Unable to handle kernel %s at virtual address %08lx\n",
		(addr < PAGE_SIZE) ? "NULL pointer dereference" :
		"paging request", addr);

	show_pte(mm, addr);
	die("Oops", regs, fsr);
	bust_spinlocks(0);
	do_exit(SIGKILL);
}

/*
 * Something tried to access memory that isn't in our memory map..
 * User mode accesses just cause a SIGSEGV
 */
static void
__do_user_fault(struct task_struct *tsk, unsigned long addr,
		unsigned int fsr, unsigned int sig, int code,
		struct pt_regs *regs)
{
	struct siginfo si;

#ifdef CONFIG_DEBUG_USER
	if (user_debug & UDBG_SEGV) {
		printk(KERN_DEBUG "%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
		       tsk->comm, sig, addr, fsr);
		show_pte(tsk->mm, addr);
		show_regs(regs);
	}
#endif

	tsk->thread.address = addr;
	tsk->thread.error_code = fsr;
	tsk->thread.trap_no = 14;
	si.si_signo = sig;
	si.si_errno = 0;
	si.si_code = code;
	si.si_addr = (void __user *)addr;
	force_sig_info(sig, &si, tsk);
}

void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->active_mm;

	/*
	 * If we are in kernel mode at this point, we
	 * have no context to handle this fault with.
	 */
	if (user_mode(regs))
		__do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
	else
		__do_kernel_fault(mm, addr, fsr, regs);
}

#define VM_FAULT_BADMAP		0x010000
#define VM_FAULT_BADACCESS	0x020000

static int
__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
		struct task_struct *tsk)
{
	struct vm_area_struct *vma;
	int fault, mask;

	vma = find_vma(mm, addr);
	fault = VM_FAULT_BADMAP;
	if (!vma)
		goto out;
	if (vma->vm_start > addr)
		goto check_stack;

	/*
	 * Ok, we have a good vm_area for this
	 * memory access, so we can handle it.
	 */
good_area:
	if (fsr & (1 << 11)) /* write? */
		mask = VM_WRITE;
	else
		mask = VM_READ|VM_EXEC|VM_WRITE;

	fault = VM_FAULT_BADACCESS;
	if (!(vma->vm_flags & mask))
		goto out;

	/*
	 * 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, addr & PAGE_MASK, fsr & (1 << 11));
	if (unlikely(fault & VM_FAULT_ERROR)) {
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGBUS)
			return fault;
		BUG();
	}
	if (fault & VM_FAULT_MAJOR)
		tsk->maj_flt++;
	else
		tsk->min_flt++;
	return fault;

out_of_memory:
	if (!is_global_init(tsk))
		goto out;

	/*
	 * If we are out of memory for pid1, sleep for a while and retry
	 */
	up_read(&mm->mmap_sem);
	yield();
	down_read(&mm->mmap_sem);
	goto survive;

check_stack:
	if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
		goto good_area;
out:
	return fault;
}

static int
do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
	struct task_struct *tsk;
	struct mm_struct *mm;
	int fault, sig, code;

	if (notify_page_fault(regs, fsr))
		return 0;

	tsk = current;
	mm  = tsk->mm;

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

	/*
	 * As per x86, we may deadlock here.  However, since the kernel only
	 * validly references user space from well defined areas of the code,
	 * we can bug out early if this is from code which shouldn't.
	 */
	if (!down_read_trylock(&mm->mmap_sem)) {
		if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
			goto no_context;
		down_read(&mm->mmap_sem);
	}

	fault = __do_page_fault(mm, addr, fsr, tsk);
	up_read(&mm->mmap_sem);

	/*
	 * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
	 */
	if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
		return 0;

	/*
	 * If we are in kernel mode at this point, we
	 * have no context to handle this fault with.
	 */
	if (!user_mode(regs))
		goto no_context;

	if (fault & VM_FAULT_OOM) {
		/*
		 * We ran out of memory, or some other thing
		 * happened to us that made us unable to handle
		 * the page fault gracefully.
		 */
		printk("VM: killing process %s\n", tsk->comm);
		do_group_exit(SIGKILL);
		return 0;
	}
	if (fault & VM_FAULT_SIGBUS) {
		/*
		 * We had some memory, but were unable to
		 * successfully fix up this page fault.
		 */
		sig = SIGBUS;
		code = BUS_ADRERR;
	} else {
		/*
		 * Something tried to access memory that
		 * isn't in our memory map..
		 */
		sig = SIGSEGV;
		code = fault == VM_FAULT_BADACCESS ?
			SEGV_ACCERR : SEGV_MAPERR;
	}

	__do_user_fault(tsk, addr, fsr, sig, code, regs);
	return 0;

no_context:
	__do_kernel_fault(mm, addr, fsr, regs);
	return 0;
}

/*
 * First Level Translation Fault Handler
 *
 * We enter here because the first level page table doesn't contain
 * a valid entry for the address.
 *
 * If the address is in kernel space (>= TASK_SIZE), then we are
 * probably faulting in the vmalloc() area.
 *
 * If the init_task's first level page tables contains the relevant
 * entry, we copy the it to this task.  If not, we send the process
 * a signal, fixup the exception, or oops the kernel.
 *
 * 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.
 */
static int
do_translation_fault(unsigned long addr, unsigned int fsr,
		     struct pt_regs *regs)
{
	unsigned int index;
	pgd_t *pgd, *pgd_k;
	pmd_t *pmd, *pmd_k;

	if (addr < TASK_SIZE)
		return do_page_fault(addr, fsr, regs);

	index = pgd_index(addr);

	/*
	 * FIXME: CP15 C1 is write only on ARMv3 architectures.
	 */
	pgd = cpu_get_pgd() + index;
	pgd_k = init_mm.pgd + index;

	if (pgd_none(*pgd_k))
		goto bad_area;

	if (!pgd_present(*pgd))
		set_pgd(pgd, *pgd_k);

	pmd_k = pmd_offset(pgd_k, addr);
	pmd   = pmd_offset(pgd, addr);

	if (pmd_none(*pmd_k))
		goto bad_area;

	copy_pmd(pmd, pmd_k);
	return 0;

bad_area:
	do_bad_area(addr, fsr, regs);
	return 0;
}

/*
 * Some section permission faults need to be handled gracefully.
 * They can happen due to a __{get,put}_user during an oops.
 */
static int
do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
	do_bad_area(addr, fsr, regs);
	return 0;
}

/*
 * This abort handler always returns "fault".
 */
static int
do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
	return 1;
}

static struct fsr_info {
	int	(*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
	int	sig;
	int	code;
	const char *name;
} fsr_info[] = {
	/*
	 * The following are the standard ARMv3 and ARMv4 aborts.  ARMv5
	 * defines these to be "precise" aborts.
	 */
	{ do_bad,		SIGSEGV, 0,		"vector exception"		   },
	{ do_bad,		SIGILL,	 BUS_ADRALN,	"alignment exception"		   },
	{ do_bad,		SIGKILL, 0,		"terminal exception"		   },
	{ do_bad,		SIGILL,	 BUS_ADRALN,	"alignment exception"		   },
	{ do_bad,		SIGBUS,	 0,		"external abort on linefetch"	   },
	{ do_translation_fault,	SIGSEGV, SEGV_MAPERR,	"section translation fault"	   },
	{ do_bad,		SIGBUS,	 0,		"external abort on linefetch"	   },
	{ do_page_fault,	SIGSEGV, SEGV_MAPERR,	"page translation fault"	   },
	{ do_bad,		SIGBUS,	 0,		"external abort on non-linefetch"  },
	{ do_bad,		SIGSEGV, SEGV_ACCERR,	"section domain fault"		   },
	{ do_bad,		SIGBUS,	 0,		"external abort on non-linefetch"  },
	{ do_bad,		SIGSEGV, SEGV_ACCERR,	"page domain fault"		   },
	{ do_bad,		SIGBUS,	 0,		"external abort on translation"	   },
	{ do_sect_fault,	SIGSEGV, SEGV_ACCERR,	"section permission fault"	   },
	{ do_bad,		SIGBUS,	 0,		"external abort on translation"	   },
	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"page permission fault"		   },
	/*
	 * The following are "imprecise" aborts, which are signalled by bit
	 * 10 of the FSR, and may not be recoverable.  These are only
	 * supported if the CPU abort handler supports bit 10.
	 */
	{ do_bad,		SIGBUS,  0,		"unknown 16"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 17"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 18"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 19"			   },
	{ do_bad,		SIGBUS,  0,		"lock abort"			   }, /* xscale */
	{ do_bad,		SIGBUS,  0,		"unknown 21"			   },
	{ do_bad,		SIGBUS,  BUS_OBJERR,	"imprecise external abort"	   }, /* xscale */
	{ do_bad,		SIGBUS,  0,		"unknown 23"			   },
	{ do_bad,		SIGBUS,  0,		"dcache parity error"		   }, /* xscale */
	{ do_bad,		SIGBUS,  0,		"unknown 25"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 26"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 27"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 28"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 29"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 30"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 31"			   }
};

void __init
hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
		int sig, const char *name)
{
	if (nr >= 0 && nr < ARRAY_SIZE(fsr_info)) {
		fsr_info[nr].fn   = fn;
		fsr_info[nr].sig  = sig;
		fsr_info[nr].name = name;
	}
}

/*
 * Dispatch a data abort to the relevant handler.
 */
asmlinkage void __exception
do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
	const struct fsr_info *inf = fsr_info + (fsr & 15) + ((fsr & (1 << 10)) >> 6);
	struct siginfo info;

	if (!inf->fn(addr, fsr, regs))
		return;

	printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
		inf->name, fsr, addr);

	info.si_signo = inf->sig;
	info.si_errno = 0;
	info.si_code  = inf->code;
	info.si_addr  = (void __user *)addr;
	arm_notify_die("", regs, &info, fsr, 0);
}

asmlinkage void __exception
do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
{
	do_translation_fault(addr, 0, regs);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/arch/arm/mm/fault.c
	3	*
	4	* Copyright (C) 1995 Linus Torvalds
	5	* Modifications for ARM processor (c) 1995-2004 Russell King
	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	*/
1da177e4 LT	11	#include <linux/module.h>
1da177e4 LT	12	#include <linux/signal.h>
1da177e4 LT	13	#include <linux/mm.h>
1da177e4 LT	14	#include <linux/init.h>
25ce1dd7	15	#include <linux/kprobes.h>
1da177e4 LT	16
	17	#include <asm/system.h>
	18	#include <asm/pgtable.h>
	19	#include <asm/tlbflush.h>
	20	#include <asm/uaccess.h>
	21
	22	#include "fault.h"
	23
25ce1dd7 NP	24
	25	#ifdef CONFIG_KPROBES
	26	static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
	27	{
	28	int ret = 0;
	29
	30	if (!user_mode(regs)) {
	31	/* kprobe_running() needs smp_processor_id() */
	32	preempt_disable();
	33	if (kprobe_running() && kprobe_fault_handler(regs, fsr))
	34	ret = 1;
	35	preempt_enable();
	36	}
	37
	38	return ret;
	39	}
	40	#else
	41	static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
	42	{
	43	return 0;
	44	}
	45	#endif
	46
1da177e4 LT	47	/*
	48	* This is useful to dump out the page tables associated with
	49	* 'addr' in mm 'mm'.
	50	*/
	51	void show_pte(struct mm_struct *mm, unsigned long addr)
	52	{
	53	pgd_t *pgd;
	54
	55	if (!mm)
	56	mm = &init_mm;
	57
	58	printk(KERN_ALERT "pgd = %p\n", mm->pgd);
	59	pgd = pgd_offset(mm, addr);
	60	printk(KERN_ALERT "[%08lx] pgd=%08lx", addr, pgd_val(pgd));
	61
	62	do {
	63	pmd_t *pmd;
	64	pte_t *pte;
	65
	66	if (pgd_none(*pgd))
	67	break;
	68
	69	if (pgd_bad(*pgd)) {
	70	printk("(bad)");
	71	break;
	72	}
	73
	74	pmd = pmd_offset(pgd, addr);
	75	#if PTRS_PER_PMD != 1
	76	printk(", pmd=%08lx", pmd_val(pmd));
	77	#endif
	78
	79	if (pmd_none(*pmd))
	80	break;
	81
	82	if (pmd_bad(*pmd)) {
	83	printk("(bad)");
	84	break;
	85	}
	86
	87	#ifndef CONFIG_HIGHMEM
	88	/* We must not map this if we have highmem enabled */
	89	pte = pte_offset_map(pmd, addr);
	90	printk(", pte=%08lx", pte_val(pte));
	91	printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE]));
	92	pte_unmap(pte);
	93	#endif
	94	} while(0);
	95
	96	printk("\n");
	97	}
	98
	99	/*
	100	* Oops. The kernel tried to access some page that wasn't present.
	101	*/
	102	static void
	103	__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
	104	struct pt_regs *regs)
	105	{
	106	/*
	107	* Are we prepared to handle this kernel fault?
	108	*/
	109	if (fixup_exception(regs))
	110	return;
111
112	/*
113	* No handler, we'll have to terminate things with extreme prejudice.
114	*/
115	bust_spinlocks(1);
116	printk(KERN_ALERT
117	"Unable to handle kernel %s at virtual address %08lx\n",
118	(addr < PAGE_SIZE) ? "NULL pointer dereference" :
119	"paging request", addr);
120
121	show_pte(mm, addr);
122	die("Oops", regs, fsr);
123	bust_spinlocks(0);
124	do_exit(SIGKILL);
125	}
126
127	/*
128	* Something tried to access memory that isn't in our memory map..
129	* User mode accesses just cause a SIGSEGV
130	*/
131	static void
132	__do_user_fault(struct task_struct *tsk, unsigned long addr,
2d137c24 AM	133	unsigned int fsr, unsigned int sig, int code,
2d137c24 AM	134	struct pt_regs *regs)
1da177e4 LT	135	{
	136	struct siginfo si;
	137
	138	#ifdef CONFIG_DEBUG_USER
	139	if (user_debug & UDBG_SEGV) {
2d137c24 AM	140	printk(KERN_DEBUG "%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
2d137c24 AM	141	tsk->comm, sig, addr, fsr);
1da177e4 LT	142	show_pte(tsk->mm, addr);
	143	show_regs(regs);
	144	}
	145	#endif
	146
	147	tsk->thread.address = addr;
	148	tsk->thread.error_code = fsr;
	149	tsk->thread.trap_no = 14;
2d137c24	150	si.si_signo = sig;
1da177e4 LT	151	si.si_errno = 0;
	152	si.si_code = code;
	153	si.si_addr = (void __user *)addr;
2d137c24	154	force_sig_info(sig, &si, tsk);
1da177e4 LT	155	}
1da177e4 LT	156
e5beac37	157	void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
1da177e4	158	{
e5beac37 RK	159	struct task_struct *tsk = current;
	160	struct mm_struct *mm = tsk->active_mm;
	161
1da177e4 LT	162	/*
	163	* If we are in kernel mode at this point, we
	164	* have no context to handle this fault with.
	165	*/
	166	if (user_mode(regs))
2d137c24	167	__do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
1da177e4 LT	168	else
	169	__do_kernel_fault(mm, addr, fsr, regs);
	170	}
	171
5c72fc5c NP	172	#define VM_FAULT_BADMAP 0x010000
5c72fc5c NP	173	#define VM_FAULT_BADACCESS 0x020000
1da177e4 LT	174
	175	static int
	176	__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
	177	struct task_struct *tsk)
	178	{
	179	struct vm_area_struct *vma;
	180	int fault, mask;
	181
	182	vma = find_vma(mm, addr);
	183	fault = VM_FAULT_BADMAP;
	184	if (!vma)
	185	goto out;
	186	if (vma->vm_start > addr)
	187	goto check_stack;
	188
	189	/*
	190	* Ok, we have a good vm_area for this
	191	* memory access, so we can handle it.
	192	*/
	193	good_area:
	194	if (fsr & (1 << 11)) /* write? */
	195	mask = VM_WRITE;
	196	else
df67b3da	197	mask = VM_READ\|VM_EXEC\|VM_WRITE;
1da177e4 LT	198
	199	fault = VM_FAULT_BADACCESS;
	200	if (!(vma->vm_flags & mask))
	201	goto out;
	202
	203	/*
	204	* If for any reason at all we couldn't handle
	205	* the fault, make sure we exit gracefully rather
	206	* than endlessly redo the fault.
	207	*/
	208	survive:
	209	fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, fsr & (1 << 11));
83c54070 NP	210	if (unlikely(fault & VM_FAULT_ERROR)) {
	211	if (fault & VM_FAULT_OOM)
	212	goto out_of_memory;
	213	else if (fault & VM_FAULT_SIGBUS)
	214	return fault;
	215	BUG();
	216	}
	217	if (fault & VM_FAULT_MAJOR)
1da177e4	218	tsk->maj_flt++;
83c54070	219	else
1da177e4	220	tsk->min_flt++;
83c54070	221	return fault;
1da177e4	222
83c54070	223	out_of_memory:
b460cbc5	224	if (!is_global_init(tsk))
1da177e4 LT	225	goto out;
	226
	227	/*
2d137c24	228	* If we are out of memory for pid1, sleep for a while and retry
1da177e4	229	*/
2d137c24	230	up_read(&mm->mmap_sem);
1da177e4	231	yield();
2d137c24	232	down_read(&mm->mmap_sem);
1da177e4 LT	233	goto survive;
	234
	235	check_stack:
	236	if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
	237	goto good_area;
	238	out:
	239	return fault;
	240	}
	241
	242	static int
	243	do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
	244	{
	245	struct task_struct *tsk;
	246	struct mm_struct *mm;
2d137c24	247	int fault, sig, code;
1da177e4	248
25ce1dd7 NP	249	if (notify_page_fault(regs, fsr))
	250	return 0;
	251
1da177e4 LT	252	tsk = current;
	253	mm = tsk->mm;
	254
	255	/*
	256	* If we're in an interrupt or have no user
	257	* context, we must not take the fault..
	258	*/
6edaf68a	259	if (in_atomic() \|\| !mm)
1da177e4 LT	260	goto no_context;
1da177e4 LT	261
840ff6a4 RK	262	/*
	263	* As per x86, we may deadlock here. However, since the kernel only
	264	* validly references user space from well defined areas of the code,
	265	* we can bug out early if this is from code which shouldn't.
	266	*/
	267	if (!down_read_trylock(&mm->mmap_sem)) {
	268	if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
	269	goto no_context;
	270	down_read(&mm->mmap_sem);
	271	}
	272
1da177e4 LT	273	fault = __do_page_fault(mm, addr, fsr, tsk);
	274	up_read(&mm->mmap_sem);
	275
	276	/*
ff2afb9d	277	* Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
1da177e4	278	*/
5c72fc5c	279	if (likely(!(fault & (VM_FAULT_ERROR \| VM_FAULT_BADMAP \| VM_FAULT_BADACCESS))))
1da177e4 LT	280	return 0;
1da177e4 LT	281
1da177e4 LT	282	/*
	283	* If we are in kernel mode at this point, we
	284	* have no context to handle this fault with.
	285	*/
	286	if (!user_mode(regs))
	287	goto no_context;
	288
83c54070	289	if (fault & VM_FAULT_OOM) {
1da177e4	290	/*
2d137c24 AM	291	* We ran out of memory, or some other thing
	292	* happened to us that made us unable to handle
	293	* the page fault gracefully.
1da177e4 LT	294	*/
1da177e4 LT	295	printk("VM: killing process %s\n", tsk->comm);
dcca2bde	296	do_group_exit(SIGKILL);
2d137c24	297	return 0;
83c54070 NP	298	}
83c54070 NP	299	if (fault & VM_FAULT_SIGBUS) {
2d137c24 AM	300	/*
	301	* We had some memory, but were unable to
	302	* successfully fix up this page fault.
	303	*/
	304	sig = SIGBUS;
	305	code = BUS_ADRERR;
83c54070	306	} else {
2d137c24 AM	307	/*
	308	* Something tried to access memory that
	309	* isn't in our memory map..
	310	*/
	311	sig = SIGSEGV;
	312	code = fault == VM_FAULT_BADACCESS ?
	313	SEGV_ACCERR : SEGV_MAPERR;
1da177e4	314	}
1da177e4	315
2d137c24 AM	316	__do_user_fault(tsk, addr, fsr, sig, code, regs);
2d137c24 AM	317	return 0;
1da177e4 LT	318
	319	no_context:
	320	__do_kernel_fault(mm, addr, fsr, regs);
	321	return 0;
	322	}
	323
	324	/*
	325	* First Level Translation Fault Handler
	326	*
	327	* We enter here because the first level page table doesn't contain
	328	* a valid entry for the address.
	329	*
	330	* If the address is in kernel space (>= TASK_SIZE), then we are
	331	* probably faulting in the vmalloc() area.
	332	*
	333	* If the init_task's first level page tables contains the relevant
	334	* entry, we copy the it to this task. If not, we send the process
	335	* a signal, fixup the exception, or oops the kernel.
	336	*
	337	* NOTE! We MUST NOT take any locks for this case. We may be in an
	338	* interrupt or a critical region, and should only copy the information
	339	* from the master page table, nothing more.
	340	*/
	341	static int
	342	do_translation_fault(unsigned long addr, unsigned int fsr,
	343	struct pt_regs *regs)
	344	{
1da177e4 LT	345	unsigned int index;
	346	pgd_t pgd, pgd_k;
	347	pmd_t pmd, pmd_k;
	348
	349	if (addr < TASK_SIZE)
	350	return do_page_fault(addr, fsr, regs);
	351
	352	index = pgd_index(addr);
	353
	354	/*
	355	* FIXME: CP15 C1 is write only on ARMv3 architectures.
	356	*/
	357	pgd = cpu_get_pgd() + index;
	358	pgd_k = init_mm.pgd + index;
	359
	360	if (pgd_none(*pgd_k))
	361	goto bad_area;
	362
	363	if (!pgd_present(*pgd))
	364	set_pgd(pgd, *pgd_k);
	365
	366	pmd_k = pmd_offset(pgd_k, addr);
	367	pmd = pmd_offset(pgd, addr);
	368
	369	if (pmd_none(*pmd_k))
	370	goto bad_area;
	371
	372	copy_pmd(pmd, pmd_k);
	373	return 0;
	374
	375	bad_area:
e5beac37	376	do_bad_area(addr, fsr, regs);
1da177e4 LT	377	return 0;
	378	}
	379
	380	/*
	381	* Some section permission faults need to be handled gracefully.
	382	* They can happen due to a __{get,put}_user during an oops.
	383	*/
	384	static int
	385	do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
	386	{
e5beac37	387	do_bad_area(addr, fsr, regs);
1da177e4 LT	388	return 0;
	389	}
	390
	391	/*
	392	* This abort handler always returns "fault".
	393	*/
	394	static int
	395	do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
	396	{
	397	return 1;
	398	}
	399
	400	static struct fsr_info {
	401	int (fn)(unsigned long addr, unsigned int fsr, struct pt_regs regs);
	402	int sig;
cfb0810e	403	int code;
1da177e4 LT	404	const char *name;
	405	} fsr_info[] = {
	406	/*
	407	* The following are the standard ARMv3 and ARMv4 aborts. ARMv5
	408	* defines these to be "precise" aborts.
	409	*/
cfb0810e RK	410	{ do_bad, SIGSEGV, 0, "vector exception" },
	411	{ do_bad, SIGILL, BUS_ADRALN, "alignment exception" },
	412	{ do_bad, SIGKILL, 0, "terminal exception" },
	413	{ do_bad, SIGILL, BUS_ADRALN, "alignment exception" },
	414	{ do_bad, SIGBUS, 0, "external abort on linefetch" },
	415	{ do_translation_fault, SIGSEGV, SEGV_MAPERR, "section translation fault" },
	416	{ do_bad, SIGBUS, 0, "external abort on linefetch" },
	417	{ do_page_fault, SIGSEGV, SEGV_MAPERR, "page translation fault" },
	418	{ do_bad, SIGBUS, 0, "external abort on non-linefetch" },
	419	{ do_bad, SIGSEGV, SEGV_ACCERR, "section domain fault" },
	420	{ do_bad, SIGBUS, 0, "external abort on non-linefetch" },
	421	{ do_bad, SIGSEGV, SEGV_ACCERR, "page domain fault" },
	422	{ do_bad, SIGBUS, 0, "external abort on translation" },
	423	{ do_sect_fault, SIGSEGV, SEGV_ACCERR, "section permission fault" },
	424	{ do_bad, SIGBUS, 0, "external abort on translation" },
	425	{ do_page_fault, SIGSEGV, SEGV_ACCERR, "page permission fault" },
1da177e4 LT	426	/*
	427	* The following are "imprecise" aborts, which are signalled by bit
	428	* 10 of the FSR, and may not be recoverable. These are only
	429	* supported if the CPU abort handler supports bit 10.
	430	*/
cfb0810e RK	431	{ do_bad, SIGBUS, 0, "unknown 16" },
	432	{ do_bad, SIGBUS, 0, "unknown 17" },
	433	{ do_bad, SIGBUS, 0, "unknown 18" },
	434	{ do_bad, SIGBUS, 0, "unknown 19" },
	435	{ do_bad, SIGBUS, 0, "lock abort" }, /* xscale */
	436	{ do_bad, SIGBUS, 0, "unknown 21" },
	437	{ do_bad, SIGBUS, BUS_OBJERR, "imprecise external abort" }, /* xscale */
	438	{ do_bad, SIGBUS, 0, "unknown 23" },
	439	{ do_bad, SIGBUS, 0, "dcache parity error" }, /* xscale */
	440	{ do_bad, SIGBUS, 0, "unknown 25" },
	441	{ do_bad, SIGBUS, 0, "unknown 26" },
	442	{ do_bad, SIGBUS, 0, "unknown 27" },
	443	{ do_bad, SIGBUS, 0, "unknown 28" },
	444	{ do_bad, SIGBUS, 0, "unknown 29" },
	445	{ do_bad, SIGBUS, 0, "unknown 30" },
	446	{ do_bad, SIGBUS, 0, "unknown 31" }
1da177e4 LT	447	};
	448
	449	void __init
	450	hook_fault_code(int nr, int (fn)(unsigned long, unsigned int, struct pt_regs ),
	451	int sig, const char *name)
	452	{
	453	if (nr >= 0 && nr < ARRAY_SIZE(fsr_info)) {
	454	fsr_info[nr].fn = fn;
	455	fsr_info[nr].sig = sig;
	456	fsr_info[nr].name = name;
	457	}
	458	}
	459
	460	/*
	461	* Dispatch a data abort to the relevant handler.
	462	*/
7ab3f8d5	463	asmlinkage void __exception
1da177e4 LT	464	do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
	465	{
	466	const struct fsr_info *inf = fsr_info + (fsr & 15) + ((fsr & (1 << 10)) >> 6);
cfb0810e	467	struct siginfo info;
1da177e4 LT	468
	469	if (!inf->fn(addr, fsr, regs))
	470	return;
	471
	472	printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
	473	inf->name, fsr, addr);
cfb0810e RK	474
	475	info.si_signo = inf->sig;
	476	info.si_errno = 0;
	477	info.si_code = inf->code;
	478	info.si_addr = (void __user *)addr;
1eeb66a1	479	arm_notify_die("", regs, &info, fsr, 0);
1da177e4 LT	480	}
1da177e4 LT	481
7ab3f8d5	482	asmlinkage void __exception
1da177e4 LT	483	do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
	484	{
	485	do_translation_fault(addr, 0, regs);
	486	}
	487