[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/hardirq.h>
#include <linux/init.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/page-flags.h>
#include <linux/sched.h>
#include <linux/highmem.h>

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

#include "fault.h"

/*
 * Fault status register encodings.  We steal bit 31 for our own purposes.
 */
#define FSR_LNX_PF		(1 << 31)
#define FSR_WRITE		(1 << 11)
#define FSR_FS4			(1 << 10)
#define FSR_FS3_0		(15)

static inline int fsr_fs(unsigned int fsr)
{
	return (fsr & FSR_FS3_0) | (fsr & FSR_FS4) >> 6;
}

#ifdef CONFIG_MMU

#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));

		if (pmd_none(*pmd))
			break;

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

		/* We must not map this if we have highmem enabled */
		if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
			break;

		pte = pte_offset_map(pmd, addr);
		printk(", *pte=%08lx", pte_val(*pte));
		printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE]));
		pte_unmap(pte);
	} while(0);

	printk("\n");
}
#else					/* CONFIG_MMU */
void show_pte(struct mm_struct *mm, unsigned long addr)
{ }
#endif					/* CONFIG_MMU */

/*
 * 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);
}

#ifdef CONFIG_MMU
#define VM_FAULT_BADMAP		0x010000
#define VM_FAULT_BADACCESS	0x020000

/*
 * Check that the permissions on the VMA allow for the fault which occurred.
 * If we encountered a write fault, we must have write permission, otherwise
 * we allow any permission.
 */
static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
{
	unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;

	if (fsr & FSR_WRITE)
		mask = VM_WRITE;
	if (fsr & FSR_LNX_PF)
		mask = VM_EXEC;

	return vma->vm_flags & mask ? false : true;
}

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

	vma = find_vma(mm, addr);
	fault = VM_FAULT_BADMAP;
	if (unlikely(!vma))
		goto out;
	if (unlikely(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 (access_error(fsr, vma)) {
		fault = VM_FAULT_BADACCESS;
		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.
	 */
	fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, (fsr & FSR_WRITE) ? FAULT_FLAG_WRITE : 0);
	if (unlikely(fault & VM_FAULT_ERROR))
		return fault;
	if (fault & VM_FAULT_MAJOR)
		tsk->maj_flt++;
	else
		tsk->min_flt++;
	return fault;

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

static int __kprobes
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);
	} else {
		/*
		 * The above down_read_trylock() might have succeeded in
		 * which case, we'll have missed the might_sleep() from
		 * down_read()
		 */
		might_sleep();
#ifdef CONFIG_DEBUG_VM
		if (!user_mode(regs) &&
		    !search_exception_tables(regs->ARM_pc))
			goto no_context;
#endif
	}

	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 (fault & VM_FAULT_OOM) {
		/*
		 * We ran out of memory, call the OOM killer, and return to
		 * userspace (which will retry the fault, or kill us if we
		 * got oom-killed)
		 */
		pagefault_out_of_memory();
		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_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;
}
#else					/* CONFIG_MMU */
static int
do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
	return 0;
}
#endif					/* CONFIG_MMU */

/*
 * 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.
 */
#ifdef CONFIG_MMU
static int __kprobes
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;
}
#else					/* CONFIG_MMU */
static int
do_translation_fault(unsigned long addr, unsigned int fsr,
		     struct pt_regs *regs)
{
	return 0;
}
#endif					/* CONFIG_MMU */

/*
 * 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_fs(fsr);
	struct siginfo info;

	if (!inf->fn(addr, fsr & ~FSR_LNX_PF, 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);
}


static struct fsr_info ifsr_info[] = {
	{ do_bad,		SIGBUS,  0,		"unknown 0"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 1"			   },
	{ do_bad,		SIGBUS,  0,		"debug event"			   },
	{ do_bad,		SIGSEGV, SEGV_ACCERR,	"section access flag fault"	   },
	{ do_bad,		SIGBUS,  0,		"unknown 4"			   },
	{ do_translation_fault,	SIGSEGV, SEGV_MAPERR,	"section translation fault"	   },
	{ do_bad,		SIGSEGV, SEGV_ACCERR,	"page access flag fault"	   },
	{ 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,		"unknown 10"			   },
	{ 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"		   },
	{ 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,		"unknown 20"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 21"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 22"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 23"			   },
	{ do_bad,		SIGBUS,  0,		"unknown 24"			   },
	{ 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"			   },
};

asmlinkage void __exception
do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs)
{
	const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr);
	struct siginfo info;

	if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
		return;

	printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
		inf->name, ifsr, 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, ifsr, 0);
}
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	13	#include <linux/mm.h>
67306da6	14	#include <linux/hardirq.h>
1da177e4	15	#include <linux/init.h>
25ce1dd7	16	#include <linux/kprobes.h>
33fa9b13	17	#include <linux/uaccess.h>
252d4c27	18	#include <linux/page-flags.h>
412bb0a6	19	#include <linux/sched.h>
65cec8e3	20	#include <linux/highmem.h>
1da177e4 LT	21
	22	#include <asm/system.h>
	23	#include <asm/pgtable.h>
	24	#include <asm/tlbflush.h>
1da177e4 LT	25
	26	#include "fault.h"
	27
c88d6aa7	28	/*
df297bf6	29	* Fault status register encodings. We steal bit 31 for our own purposes.
c88d6aa7	30	*/
df297bf6	31	#define FSR_LNX_PF (1 << 31)
c88d6aa7 RK	32	#define FSR_WRITE (1 << 11)
	33	#define FSR_FS4 (1 << 10)
	34	#define FSR_FS3_0 (15)
	35
	36	static inline int fsr_fs(unsigned int fsr)
	37	{
	38	return (fsr & FSR_FS3_0) \| (fsr & FSR_FS4) >> 6;
	39	}
	40
09529f7a	41	#ifdef CONFIG_MMU
25ce1dd7 NP	42
	43	#ifdef CONFIG_KPROBES
	44	static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
	45	{
	46	int ret = 0;
	47
	48	if (!user_mode(regs)) {
	49	/* kprobe_running() needs smp_processor_id() */
	50	preempt_disable();
	51	if (kprobe_running() && kprobe_fault_handler(regs, fsr))
	52	ret = 1;
	53	preempt_enable();
	54	}
	55
	56	return ret;
	57	}
	58	#else
	59	static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
	60	{
	61	return 0;
	62	}
	63	#endif
	64
1da177e4 LT	65	/*
	66	* This is useful to dump out the page tables associated with
	67	* 'addr' in mm 'mm'.
	68	*/
	69	void show_pte(struct mm_struct *mm, unsigned long addr)
	70	{
	71	pgd_t *pgd;
	72
	73	if (!mm)
	74	mm = &init_mm;
	75
	76	printk(KERN_ALERT "pgd = %p\n", mm->pgd);
	77	pgd = pgd_offset(mm, addr);
	78	printk(KERN_ALERT "[%08lx] pgd=%08lx", addr, pgd_val(pgd));
	79
	80	do {
	81	pmd_t *pmd;
	82	pte_t *pte;
	83
	84	if (pgd_none(*pgd))
	85	break;
	86
	87	if (pgd_bad(*pgd)) {
	88	printk("(bad)");
	89	break;
	90	}
	91
	92	pmd = pmd_offset(pgd, addr);
da46c79a NP	93	if (PTRS_PER_PMD != 1)
da46c79a NP	94	printk(", pmd=%08lx", pmd_val(pmd));
1da177e4 LT	95
	96	if (pmd_none(*pmd))
	97	break;
	98
	99	if (pmd_bad(*pmd)) {
	100	printk("(bad)");
	101	break;
	102	}
	103
1da177e4	104	/* We must not map this if we have highmem enabled */
252d4c27 NP	105	if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
	106	break;
	107
1da177e4 LT	108	pte = pte_offset_map(pmd, addr);
	109	printk(", pte=%08lx", pte_val(pte));
	110	printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE]));
	111	pte_unmap(pte);
1da177e4 LT	112	} while(0);
	113
	114	printk("\n");
	115	}
09529f7a CM	116	#else /* CONFIG_MMU */
	117	void show_pte(struct mm_struct *mm, unsigned long addr)
	118	{ }
	119	#endif /* CONFIG_MMU */
1da177e4 LT	120
	121	/*
	122	* Oops. The kernel tried to access some page that wasn't present.
	123	*/
	124	static void
	125	__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
	126	struct pt_regs *regs)
	127	{
	128	/*
	129	* Are we prepared to handle this kernel fault?
	130	*/
	131	if (fixup_exception(regs))
	132	return;
	133
	134	/*
	135	* No handler, we'll have to terminate things with extreme prejudice.
	136	*/
	137	bust_spinlocks(1);
	138	printk(KERN_ALERT
	139	"Unable to handle kernel %s at virtual address %08lx\n",
	140	(addr < PAGE_SIZE) ? "NULL pointer dereference" :
	141	"paging request", addr);
	142
	143	show_pte(mm, addr);
	144	die("Oops", regs, fsr);
	145	bust_spinlocks(0);
	146	do_exit(SIGKILL);
	147	}
	148
	149	/*
	150	* Something tried to access memory that isn't in our memory map..
	151	* User mode accesses just cause a SIGSEGV
	152	*/
	153	static void
	154	__do_user_fault(struct task_struct *tsk, unsigned long addr,
2d137c24 AM	155	unsigned int fsr, unsigned int sig, int code,
2d137c24 AM	156	struct pt_regs *regs)
1da177e4 LT	157	{
	158	struct siginfo si;
	159
	160	#ifdef CONFIG_DEBUG_USER
	161	if (user_debug & UDBG_SEGV) {
2d137c24 AM	162	printk(KERN_DEBUG "%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
2d137c24 AM	163	tsk->comm, sig, addr, fsr);
1da177e4 LT	164	show_pte(tsk->mm, addr);
	165	show_regs(regs);
	166	}
	167	#endif
	168
	169	tsk->thread.address = addr;
	170	tsk->thread.error_code = fsr;
	171	tsk->thread.trap_no = 14;
2d137c24	172	si.si_signo = sig;
1da177e4 LT	173	si.si_errno = 0;
	174	si.si_code = code;
	175	si.si_addr = (void __user *)addr;
2d137c24	176	force_sig_info(sig, &si, tsk);
1da177e4 LT	177	}
1da177e4 LT	178
e5beac37	179	void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
1da177e4	180	{
e5beac37 RK	181	struct task_struct *tsk = current;
	182	struct mm_struct *mm = tsk->active_mm;
	183
1da177e4 LT	184	/*
	185	* If we are in kernel mode at this point, we
	186	* have no context to handle this fault with.
	187	*/
	188	if (user_mode(regs))
2d137c24	189	__do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
1da177e4 LT	190	else
	191	__do_kernel_fault(mm, addr, fsr, regs);
	192	}
	193
09529f7a	194	#ifdef CONFIG_MMU
5c72fc5c NP	195	#define VM_FAULT_BADMAP 0x010000
5c72fc5c NP	196	#define VM_FAULT_BADACCESS 0x020000
1da177e4	197
d374bf14 RK	198	/*
	199	* Check that the permissions on the VMA allow for the fault which occurred.
	200	* If we encountered a write fault, we must have write permission, otherwise
	201	* we allow any permission.
	202	*/
	203	static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
	204	{
	205	unsigned int mask = VM_READ \| VM_WRITE \| VM_EXEC;
	206
	207	if (fsr & FSR_WRITE)
	208	mask = VM_WRITE;
df297bf6 RK	209	if (fsr & FSR_LNX_PF)
df297bf6 RK	210	mask = VM_EXEC;
d374bf14 RK	211
	212	return vma->vm_flags & mask ? false : true;
	213	}
	214
	215	static int __kprobes
1da177e4 LT	216	__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
	217	struct task_struct *tsk)
	218	{
	219	struct vm_area_struct *vma;
d374bf14	220	int fault;
1da177e4 LT	221
	222	vma = find_vma(mm, addr);
	223	fault = VM_FAULT_BADMAP;
d374bf14	224	if (unlikely(!vma))
1da177e4	225	goto out;
d374bf14	226	if (unlikely(vma->vm_start > addr))
1da177e4 LT	227	goto check_stack;
	228
	229	/*
	230	* Ok, we have a good vm_area for this
	231	* memory access, so we can handle it.
	232	*/
	233	good_area:
d374bf14 RK	234	if (access_error(fsr, vma)) {
d374bf14 RK	235	fault = VM_FAULT_BADACCESS;
1da177e4	236	goto out;
d374bf14	237	}
1da177e4 LT	238
1da177e4 LT	239	/*
b42c6344 RK	240	* If for any reason at all we couldn't handle the fault, make
b42c6344 RK	241	* sure we exit gracefully rather than endlessly redo the fault.
1da177e4	242	*/
c88d6aa7	243	fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, (fsr & FSR_WRITE) ? FAULT_FLAG_WRITE : 0);
b42c6344 RK	244	if (unlikely(fault & VM_FAULT_ERROR))
b42c6344 RK	245	return fault;
83c54070	246	if (fault & VM_FAULT_MAJOR)
1da177e4	247	tsk->maj_flt++;
83c54070	248	else
1da177e4	249	tsk->min_flt++;
83c54070	250	return fault;
1da177e4	251
1da177e4 LT	252	check_stack:
	253	if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
	254	goto good_area;
	255	out:
	256	return fault;
	257	}
	258
785d3cd2	259	static int __kprobes
1da177e4 LT	260	do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
	261	{
	262	struct task_struct *tsk;
	263	struct mm_struct *mm;
2d137c24	264	int fault, sig, code;
1da177e4	265
25ce1dd7 NP	266	if (notify_page_fault(regs, fsr))
	267	return 0;
	268
1da177e4 LT	269	tsk = current;
	270	mm = tsk->mm;
	271
	272	/*
	273	* If we're in an interrupt or have no user
	274	* context, we must not take the fault..
	275	*/
6edaf68a	276	if (in_atomic() \|\| !mm)
1da177e4 LT	277	goto no_context;
1da177e4 LT	278
840ff6a4 RK	279	/*
	280	* As per x86, we may deadlock here. However, since the kernel only
	281	* validly references user space from well defined areas of the code,
	282	* we can bug out early if this is from code which shouldn't.
	283	*/
	284	if (!down_read_trylock(&mm->mmap_sem)) {
	285	if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
	286	goto no_context;
	287	down_read(&mm->mmap_sem);
bf456992 RK	288	} else {
	289	/*
	290	* The above down_read_trylock() might have succeeded in
	291	* which case, we'll have missed the might_sleep() from
	292	* down_read()
	293	*/
	294	might_sleep();
1d212712 ID	295	#ifdef CONFIG_DEBUG_VM
	296	if (!user_mode(regs) &&
	297	!search_exception_tables(regs->ARM_pc))
	298	goto no_context;
	299	#endif
840ff6a4 RK	300	}
840ff6a4 RK	301
1da177e4 LT	302	fault = __do_page_fault(mm, addr, fsr, tsk);
	303	up_read(&mm->mmap_sem);
	304
	305	/*
ff2afb9d	306	* Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
1da177e4	307	*/
5c72fc5c	308	if (likely(!(fault & (VM_FAULT_ERROR \| VM_FAULT_BADMAP \| VM_FAULT_BADACCESS))))
1da177e4 LT	309	return 0;
1da177e4 LT	310
b42c6344 RK	311	if (fault & VM_FAULT_OOM) {
	312	/*
	313	* We ran out of memory, call the OOM killer, and return to
	314	* userspace (which will retry the fault, or kill us if we
	315	* got oom-killed)
	316	*/
	317	pagefault_out_of_memory();
	318	return 0;
	319	}
	320
1da177e4 LT	321	/*
	322	* If we are in kernel mode at this point, we
	323	* have no context to handle this fault with.
	324	*/
	325	if (!user_mode(regs))
	326	goto no_context;
	327
83c54070	328	if (fault & VM_FAULT_SIGBUS) {
2d137c24 AM	329	/*
	330	* We had some memory, but were unable to
	331	* successfully fix up this page fault.
	332	*/
	333	sig = SIGBUS;
	334	code = BUS_ADRERR;
83c54070	335	} else {
2d137c24 AM	336	/*
	337	* Something tried to access memory that
	338	* isn't in our memory map..
	339	*/
	340	sig = SIGSEGV;
	341	code = fault == VM_FAULT_BADACCESS ?
	342	SEGV_ACCERR : SEGV_MAPERR;
1da177e4	343	}
1da177e4	344
2d137c24 AM	345	__do_user_fault(tsk, addr, fsr, sig, code, regs);
2d137c24 AM	346	return 0;
1da177e4 LT	347
	348	no_context:
	349	__do_kernel_fault(mm, addr, fsr, regs);
	350	return 0;
	351	}
09529f7a CM	352	#else /* CONFIG_MMU */
	353	static int
	354	do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
	355	{
	356	return 0;
	357	}
	358	#endif /* CONFIG_MMU */
1da177e4 LT	359
	360	/*
	361	* First Level Translation Fault Handler
	362	*
	363	* We enter here because the first level page table doesn't contain
	364	* a valid entry for the address.
	365	*
	366	* If the address is in kernel space (>= TASK_SIZE), then we are
	367	* probably faulting in the vmalloc() area.
	368	*
	369	* If the init_task's first level page tables contains the relevant
	370	* entry, we copy the it to this task. If not, we send the process
	371	* a signal, fixup the exception, or oops the kernel.
	372	*
	373	* NOTE! We MUST NOT take any locks for this case. We may be in an
	374	* interrupt or a critical region, and should only copy the information
	375	* from the master page table, nothing more.
	376	*/
09529f7a	377	#ifdef CONFIG_MMU
785d3cd2	378	static int __kprobes
1da177e4 LT	379	do_translation_fault(unsigned long addr, unsigned int fsr,
	380	struct pt_regs *regs)
	381	{
1da177e4 LT	382	unsigned int index;
	383	pgd_t pgd, pgd_k;
	384	pmd_t pmd, pmd_k;
	385
	386	if (addr < TASK_SIZE)
	387	return do_page_fault(addr, fsr, regs);
	388
	389	index = pgd_index(addr);
	390
	391	/*
	392	* FIXME: CP15 C1 is write only on ARMv3 architectures.
	393	*/
	394	pgd = cpu_get_pgd() + index;
	395	pgd_k = init_mm.pgd + index;
	396
	397	if (pgd_none(*pgd_k))
	398	goto bad_area;
	399
	400	if (!pgd_present(*pgd))
	401	set_pgd(pgd, *pgd_k);
	402
	403	pmd_k = pmd_offset(pgd_k, addr);
	404	pmd = pmd_offset(pgd, addr);
	405
	406	if (pmd_none(*pmd_k))
	407	goto bad_area;
	408
	409	copy_pmd(pmd, pmd_k);
	410	return 0;
	411
	412	bad_area:
e5beac37	413	do_bad_area(addr, fsr, regs);
1da177e4 LT	414	return 0;
1da177e4 LT	415	}
09529f7a CM	416	#else /* CONFIG_MMU */
	417	static int
	418	do_translation_fault(unsigned long addr, unsigned int fsr,
	419	struct pt_regs *regs)
	420	{
	421	return 0;
	422	}
	423	#endif /* CONFIG_MMU */
1da177e4 LT	424
	425	/*
	426	* Some section permission faults need to be handled gracefully.
	427	* They can happen due to a __{get,put}_user during an oops.
	428	*/
	429	static int
	430	do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
	431	{
e5beac37	432	do_bad_area(addr, fsr, regs);
1da177e4 LT	433	return 0;
	434	}
	435
	436	/*
	437	* This abort handler always returns "fault".
	438	*/
	439	static int
	440	do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
	441	{
	442	return 1;
	443	}
	444
	445	static struct fsr_info {
	446	int (fn)(unsigned long addr, unsigned int fsr, struct pt_regs regs);
	447	int sig;
cfb0810e	448	int code;
1da177e4 LT	449	const char *name;
	450	} fsr_info[] = {
	451	/*
	452	* The following are the standard ARMv3 and ARMv4 aborts. ARMv5
	453	* defines these to be "precise" aborts.
	454	*/
cfb0810e RK	455	{ do_bad, SIGSEGV, 0, "vector exception" },
	456	{ do_bad, SIGILL, BUS_ADRALN, "alignment exception" },
	457	{ do_bad, SIGKILL, 0, "terminal exception" },
	458	{ do_bad, SIGILL, BUS_ADRALN, "alignment exception" },
	459	{ do_bad, SIGBUS, 0, "external abort on linefetch" },
	460	{ do_translation_fault, SIGSEGV, SEGV_MAPERR, "section translation fault" },
	461	{ do_bad, SIGBUS, 0, "external abort on linefetch" },
	462	{ do_page_fault, SIGSEGV, SEGV_MAPERR, "page translation fault" },
	463	{ do_bad, SIGBUS, 0, "external abort on non-linefetch" },
	464	{ do_bad, SIGSEGV, SEGV_ACCERR, "section domain fault" },
	465	{ do_bad, SIGBUS, 0, "external abort on non-linefetch" },
	466	{ do_bad, SIGSEGV, SEGV_ACCERR, "page domain fault" },
	467	{ do_bad, SIGBUS, 0, "external abort on translation" },
	468	{ do_sect_fault, SIGSEGV, SEGV_ACCERR, "section permission fault" },
	469	{ do_bad, SIGBUS, 0, "external abort on translation" },
	470	{ do_page_fault, SIGSEGV, SEGV_ACCERR, "page permission fault" },
1da177e4 LT	471	/*
	472	* The following are "imprecise" aborts, which are signalled by bit
	473	* 10 of the FSR, and may not be recoverable. These are only
	474	* supported if the CPU abort handler supports bit 10.
	475	*/
cfb0810e RK	476	{ do_bad, SIGBUS, 0, "unknown 16" },
	477	{ do_bad, SIGBUS, 0, "unknown 17" },
	478	{ do_bad, SIGBUS, 0, "unknown 18" },
	479	{ do_bad, SIGBUS, 0, "unknown 19" },
	480	{ do_bad, SIGBUS, 0, "lock abort" }, /* xscale */
	481	{ do_bad, SIGBUS, 0, "unknown 21" },
	482	{ do_bad, SIGBUS, BUS_OBJERR, "imprecise external abort" }, /* xscale */
	483	{ do_bad, SIGBUS, 0, "unknown 23" },
	484	{ do_bad, SIGBUS, 0, "dcache parity error" }, /* xscale */
	485	{ do_bad, SIGBUS, 0, "unknown 25" },
	486	{ do_bad, SIGBUS, 0, "unknown 26" },
	487	{ do_bad, SIGBUS, 0, "unknown 27" },
	488	{ do_bad, SIGBUS, 0, "unknown 28" },
	489	{ do_bad, SIGBUS, 0, "unknown 29" },
	490	{ do_bad, SIGBUS, 0, "unknown 30" },
	491	{ do_bad, SIGBUS, 0, "unknown 31" }
1da177e4 LT	492	};
	493
	494	void __init
	495	hook_fault_code(int nr, int (fn)(unsigned long, unsigned int, struct pt_regs ),
	496	int sig, const char *name)
	497	{
	498	if (nr >= 0 && nr < ARRAY_SIZE(fsr_info)) {
	499	fsr_info[nr].fn = fn;
	500	fsr_info[nr].sig = sig;
	501	fsr_info[nr].name = name;
	502	}
	503	}
	504
	505	/*
	506	* Dispatch a data abort to the relevant handler.
	507	*/
7ab3f8d5	508	asmlinkage void __exception
1da177e4 LT	509	do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
1da177e4 LT	510	{
c88d6aa7	511	const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
cfb0810e	512	struct siginfo info;
1da177e4	513
df297bf6	514	if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
1da177e4 LT	515	return;
	516
	517	printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
	518	inf->name, fsr, addr);
cfb0810e RK	519
	520	info.si_signo = inf->sig;
	521	info.si_errno = 0;
	522	info.si_code = inf->code;
	523	info.si_addr = (void __user *)addr;
1eeb66a1	524	arm_notify_die("", regs, &info, fsr, 0);
1da177e4 LT	525	}
1da177e4 LT	526
d25ef8b8 KS	527
	528	static struct fsr_info ifsr_info[] = {
	529	{ do_bad, SIGBUS, 0, "unknown 0" },
	530	{ do_bad, SIGBUS, 0, "unknown 1" },
	531	{ do_bad, SIGBUS, 0, "debug event" },
	532	{ do_bad, SIGSEGV, SEGV_ACCERR, "section access flag fault" },
	533	{ do_bad, SIGBUS, 0, "unknown 4" },
	534	{ do_translation_fault, SIGSEGV, SEGV_MAPERR, "section translation fault" },
	535	{ do_bad, SIGSEGV, SEGV_ACCERR, "page access flag fault" },
	536	{ do_page_fault, SIGSEGV, SEGV_MAPERR, "page translation fault" },
	537	{ do_bad, SIGBUS, 0, "external abort on non-linefetch" },
	538	{ do_bad, SIGSEGV, SEGV_ACCERR, "section domain fault" },
	539	{ do_bad, SIGBUS, 0, "unknown 10" },
	540	{ do_bad, SIGSEGV, SEGV_ACCERR, "page domain fault" },
	541	{ do_bad, SIGBUS, 0, "external abort on translation" },
	542	{ do_sect_fault, SIGSEGV, SEGV_ACCERR, "section permission fault" },
	543	{ do_bad, SIGBUS, 0, "external abort on translation" },
	544	{ do_page_fault, SIGSEGV, SEGV_ACCERR, "page permission fault" },
	545	{ do_bad, SIGBUS, 0, "unknown 16" },
	546	{ do_bad, SIGBUS, 0, "unknown 17" },
	547	{ do_bad, SIGBUS, 0, "unknown 18" },
	548	{ do_bad, SIGBUS, 0, "unknown 19" },
	549	{ do_bad, SIGBUS, 0, "unknown 20" },
	550	{ do_bad, SIGBUS, 0, "unknown 21" },
	551	{ do_bad, SIGBUS, 0, "unknown 22" },
	552	{ do_bad, SIGBUS, 0, "unknown 23" },
	553	{ do_bad, SIGBUS, 0, "unknown 24" },
	554	{ do_bad, SIGBUS, 0, "unknown 25" },
	555	{ do_bad, SIGBUS, 0, "unknown 26" },
	556	{ do_bad, SIGBUS, 0, "unknown 27" },
	557	{ do_bad, SIGBUS, 0, "unknown 28" },
	558	{ do_bad, SIGBUS, 0, "unknown 29" },
	559	{ do_bad, SIGBUS, 0, "unknown 30" },
	560	{ do_bad, SIGBUS, 0, "unknown 31" },
	561	};
	562
7ab3f8d5	563	asmlinkage void __exception
4fb28474	564	do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs)
1da177e4	565	{
d25ef8b8 KS	566	const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr);
	567	struct siginfo info;
	568
	569	if (!inf->fn(addr, ifsr \| FSR_LNX_PF, regs))
	570	return;
	571
	572	printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
	573	inf->name, ifsr, addr);
	574
	575	info.si_signo = inf->sig;
	576	info.si_errno = 0;
	577	info.si_code = inf->code;
	578	info.si_addr = (void __user *)addr;
	579	arm_notify_die("", regs, &info, ifsr, 0);
1da177e4 LT	580	}
1da177e4 LT	581