[linux-block.git] / arch / nios2 / mm / fault.c

/*
 * Copyright (C) 2009 Wind River Systems Inc
 *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
 *
 * based on arch/mips/mm/fault.c which is:
 *
 * Copyright (C) 1995-2000 Ralf Baechle
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */

#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/extable.h>
#include <linux/uaccess.h>

#include <asm/mmu_context.h>
#include <asm/traps.h>

#define EXC_SUPERV_INSN_ACCESS	9  /* Supervisor only instruction address */
#define EXC_SUPERV_DATA_ACCESS	11 /* Supervisor only data address */
#define EXC_X_PROTECTION_FAULT	13 /* TLB permission violation (x) */
#define EXC_R_PROTECTION_FAULT	14 /* TLB permission violation (r) */
#define EXC_W_PROTECTION_FAULT	15 /* TLB permission violation (w) */

/*
 * This routine handles page faults.  It determines the address,
 * and the problem, and then passes it off to one of the appropriate
 * routines.
 */
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long cause,
				unsigned long address)
{
	struct vm_area_struct *vma = NULL;
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	int code = SEGV_MAPERR;
	vm_fault_t fault;
	unsigned int flags = FAULT_FLAG_DEFAULT;

	cause >>= 2;

	/* Restart the instruction */
	regs->ea -= 4;

	/*
	 * We fault-in kernel-space virtual memory on-demand. The
	 * 'reference' page table is init_mm.pgd.
	 *
	 * 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.
	 */
	if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) {
		if (user_mode(regs))
			goto bad_area_nosemaphore;
		else
			goto vmalloc_fault;
	}

	if (unlikely(address >= TASK_SIZE))
		goto bad_area_nosemaphore;

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

	if (user_mode(regs))
		flags |= FAULT_FLAG_USER;

	if (!mmap_read_trylock(mm)) {
		if (!user_mode(regs) && !search_exception_tables(regs->ea))
			goto bad_area_nosemaphore;
retry:
		mmap_read_lock(mm);
	}

	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;

	switch (cause) {
	case EXC_SUPERV_INSN_ACCESS:
		goto bad_area;
	case EXC_SUPERV_DATA_ACCESS:
		goto bad_area;
	case EXC_X_PROTECTION_FAULT:
		if (!(vma->vm_flags & VM_EXEC))
			goto bad_area;
		break;
	case EXC_R_PROTECTION_FAULT:
		if (!(vma->vm_flags & VM_READ))
			goto bad_area;
		break;
	case EXC_W_PROTECTION_FAULT:
		if (!(vma->vm_flags & VM_WRITE))
			goto bad_area;
		flags = FAULT_FLAG_WRITE;
		break;
	}

	/*
	 * 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(vma, address, flags);

	if (fault_signal_pending(fault, regs))
		return;

	if (unlikely(fault & VM_FAULT_ERROR)) {
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGSEGV)
			goto bad_area;
		else if (fault & VM_FAULT_SIGBUS)
			goto do_sigbus;
		BUG();
	}

	/*
	 * Major/minor page fault accounting is only done on the
	 * initial attempt. If we go through a retry, it is extremely
	 * likely that the page will be found in page cache at that point.
	 */
	if (flags & FAULT_FLAG_ALLOW_RETRY) {
		if (fault & VM_FAULT_MAJOR)
			current->maj_flt++;
		else
			current->min_flt++;
		if (fault & VM_FAULT_RETRY) {
			flags |= FAULT_FLAG_TRIED;

			/*
			 * No need to up_read(&mm->mmap_sem) as we would
			 * have already released it in __lock_page_or_retry
			 * in mm/filemap.c.
			 */

			goto retry;
		}
	}

	mmap_read_unlock(mm);
	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:
	mmap_read_unlock(mm);

bad_area_nosemaphore:
	/* User mode accesses just cause a SIGSEGV */
	if (user_mode(regs)) {
		if (unhandled_signal(current, SIGSEGV) && printk_ratelimit()) {
			pr_info("%s: unhandled page fault (%d) at 0x%08lx, "
				"cause %ld\n", current->comm, SIGSEGV, address, cause);
			show_regs(regs);
		}
		_exception(SIGSEGV, regs, code, address);
		return;
	}

no_context:
	/* Are we prepared to handle this kernel fault? */
	if (fixup_exception(regs))
		return;

	/*
	 * Oops. The kernel tried to access some bad page. We'll have to
	 * terminate things with extreme prejudice.
	 */
	bust_spinlocks(1);

	pr_alert("Unable to handle kernel %s at virtual address %08lx",
		address < PAGE_SIZE ? "NULL pointer dereference" :
		"paging request", address);
	pr_alert("ea = %08lx, ra = %08lx, cause = %ld\n", regs->ea, regs->ra,
		cause);
	panic("Oops");
	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:
	mmap_read_unlock(mm);
	if (!user_mode(regs))
		goto no_context;
	pagefault_out_of_memory();
	return;

do_sigbus:
	mmap_read_unlock(mm);

	/* Kernel mode? Handle exceptions or die */
	if (!user_mode(regs))
		goto no_context;

	_exception(SIGBUS, regs, BUS_ADRERR, address);
	return;

vmalloc_fault:
	{
		/*
		 * Synchronize this task's top level page-table
		 * with the 'reference' page table.
		 *
		 * Do _not_ use "tsk" here. We might be inside
		 * an interrupt in the middle of a task switch..
		 */
		int offset = pgd_index(address);
		pgd_t *pgd, *pgd_k;
		p4d_t *p4d, *p4d_k;
		pud_t *pud, *pud_k;
		pmd_t *pmd, *pmd_k;
		pte_t *pte_k;

		pgd = pgd_current + offset;
		pgd_k = init_mm.pgd + offset;

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

		p4d = p4d_offset(pgd, address);
		p4d_k = p4d_offset(pgd_k, address);
		if (!p4d_present(*p4d_k))
			goto no_context;
		pud = pud_offset(p4d, address);
		pud_k = pud_offset(p4d_k, address);
		if (!pud_present(*pud_k))
			goto no_context;
		pmd = pmd_offset(pud, address);
		pmd_k = pmd_offset(pud_k, address);
		if (!pmd_present(*pmd_k))
			goto no_context;
		set_pmd(pmd, *pmd_k);

		pte_k = pte_offset_kernel(pmd_k, address);
		if (!pte_present(*pte_k))
			goto no_context;

		flush_tlb_kernel_page(address);
		return;
	}
}
Commit	Line	Data
862674d4 LFT	1	/*
	2	* Copyright (C) 2009 Wind River Systems Inc
	3	* Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
	4	*
	5	* based on arch/mips/mm/fault.c which is:
	6	*
	7	* Copyright (C) 1995-2000 Ralf Baechle
	8	*
	9	* This file is subject to the terms and conditions of the GNU General Public
	10	* License. See the file "COPYING" in the main directory of this archive
	11	* for more details.
	12	*/
	13
	14	#include <linux/signal.h>
	15	#include <linux/sched.h>
b17b0153	16	#include <linux/sched/debug.h>
862674d4 LFT	17	#include <linux/interrupt.h>
	18	#include <linux/kernel.h>
	19	#include <linux/errno.h>
	20	#include <linux/string.h>
	21	#include <linux/types.h>
	22	#include <linux/ptrace.h>
	23	#include <linux/mman.h>
	24	#include <linux/mm.h>
7e227e88	25	#include <linux/extable.h>
862674d4	26	#include <linux/uaccess.h>
862674d4 LFT	27
	28	#include <asm/mmu_context.h>
	29	#include <asm/traps.h>
	30
	31	#define EXC_SUPERV_INSN_ACCESS 9 /* Supervisor only instruction address */
	32	#define EXC_SUPERV_DATA_ACCESS 11 /* Supervisor only data address */
	33	#define EXC_X_PROTECTION_FAULT 13 /* TLB permission violation (x) */
	34	#define EXC_R_PROTECTION_FAULT 14 /* TLB permission violation (r) */
	35	#define EXC_W_PROTECTION_FAULT 15 /* TLB permission violation (w) */
	36
	37	/*
	38	* This routine handles page faults. It determines the address,
	39	* and the problem, and then passes it off to one of the appropriate
	40	* routines.
	41	*/
	42	asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long cause,
	43	unsigned long address)
	44	{
	45	struct vm_area_struct *vma = NULL;
	46	struct task_struct *tsk = current;
	47	struct mm_struct *mm = tsk->mm;
	48	int code = SEGV_MAPERR;
50a7ca3c	49	vm_fault_t fault;
dde16072	50	unsigned int flags = FAULT_FLAG_DEFAULT;
862674d4 LFT	51
	52	cause >>= 2;
	53
	54	/* Restart the instruction */
	55	regs->ea -= 4;
	56
	57	/*
	58	* We fault-in kernel-space virtual memory on-demand. The
	59	* 'reference' page table is init_mm.pgd.
	60	*
	61	* NOTE! We MUST NOT take any locks for this case. We may
	62	* be in an interrupt or a critical region, and should
	63	* only copy the information from the master page table,
	64	* nothing more.
	65	*/
	66	if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) {
	67	if (user_mode(regs))
	68	goto bad_area_nosemaphore;
	69	else
	70	goto vmalloc_fault;
	71	}
	72
	73	if (unlikely(address >= TASK_SIZE))
	74	goto bad_area_nosemaphore;
	75
	76	/*
	77	* If we're in an interrupt or have no user
	78	* context, we must not take the fault..
	79	*/
70ffdb93	80	if (faulthandler_disabled() \|\| !mm)
862674d4 LFT	81	goto bad_area_nosemaphore;
	82
	83	if (user_mode(regs))
	84	flags \|= FAULT_FLAG_USER;
	85
d8ed45c5	86	if (!mmap_read_trylock(mm)) {
862674d4 LFT	87	if (!user_mode(regs) && !search_exception_tables(regs->ea))
862674d4 LFT	88	goto bad_area_nosemaphore;
96f3a5cc	89	retry:
d8ed45c5	90	mmap_read_lock(mm);
862674d4 LFT	91	}
	92
	93	vma = find_vma(mm, address);
	94	if (!vma)
	95	goto bad_area;
	96	if (vma->vm_start <= address)
	97	goto good_area;
	98	if (!(vma->vm_flags & VM_GROWSDOWN))
	99	goto bad_area;
	100	if (expand_stack(vma, address))
	101	goto bad_area;
	102	/*
	103	* Ok, we have a good vm_area for this memory access, so
	104	* we can handle it..
	105	*/
	106	good_area:
	107	code = SEGV_ACCERR;
	108
	109	switch (cause) {
	110	case EXC_SUPERV_INSN_ACCESS:
	111	goto bad_area;
	112	case EXC_SUPERV_DATA_ACCESS:
	113	goto bad_area;
	114	case EXC_X_PROTECTION_FAULT:
	115	if (!(vma->vm_flags & VM_EXEC))
	116	goto bad_area;
	117	break;
	118	case EXC_R_PROTECTION_FAULT:
	119	if (!(vma->vm_flags & VM_READ))
	120	goto bad_area;
	121	break;
	122	case EXC_W_PROTECTION_FAULT:
	123	if (!(vma->vm_flags & VM_WRITE))
	124	goto bad_area;
	125	flags = FAULT_FLAG_WRITE;
	126	break;
	127	}
	128
862674d4 LFT	129	/*
	130	* If for any reason at all we couldn't handle the fault,
	131	* make sure we exit gracefully rather than endlessly redo
	132	* the fault.
	133	*/
dcddffd4	134	fault = handle_mm_fault(vma, address, flags);
96f3a5cc	135
4ef87322	136	if (fault_signal_pending(fault, regs))
96f3a5cc LFT	137	return;
96f3a5cc LFT	138
862674d4 LFT	139	if (unlikely(fault & VM_FAULT_ERROR)) {
	140	if (fault & VM_FAULT_OOM)
	141	goto out_of_memory;
33692f27 LT	142	else if (fault & VM_FAULT_SIGSEGV)
33692f27 LT	143	goto bad_area;
862674d4 LFT	144	else if (fault & VM_FAULT_SIGBUS)
	145	goto do_sigbus;
	146	BUG();
	147	}
96f3a5cc LFT	148
	149	/*
	150	* Major/minor page fault accounting is only done on the
	151	* initial attempt. If we go through a retry, it is extremely
	152	* likely that the page will be found in page cache at that point.
	153	*/
	154	if (flags & FAULT_FLAG_ALLOW_RETRY) {
	155	if (fault & VM_FAULT_MAJOR)
	156	current->maj_flt++;
	157	else
	158	current->min_flt++;
	159	if (fault & VM_FAULT_RETRY) {
96f3a5cc LFT	160	flags \|= FAULT_FLAG_TRIED;
	161
	162	/*
	163	* No need to up_read(&mm->mmap_sem) as we would
	164	* have already released it in __lock_page_or_retry
	165	* in mm/filemap.c.
	166	*/
	167
	168	goto retry;
	169	}
	170	}
862674d4	171
d8ed45c5	172	mmap_read_unlock(mm);
862674d4 LFT	173	return;
	174
	175	/*
	176	* Something tried to access memory that isn't in our memory map..
	177	* Fix it, but check if it's kernel or user first..
	178	*/
	179	bad_area:
d8ed45c5	180	mmap_read_unlock(mm);
862674d4 LFT	181
	182	bad_area_nosemaphore:
	183	/* User mode accesses just cause a SIGSEGV */
	184	if (user_mode(regs)) {
a3248d60 CLT	185	if (unhandled_signal(current, SIGSEGV) && printk_ratelimit()) {
	186	pr_info("%s: unhandled page fault (%d) at 0x%08lx, "
	187	"cause %ld\n", current->comm, SIGSEGV, address, cause);
	188	show_regs(regs);
	189	}
862674d4 LFT	190	_exception(SIGSEGV, regs, code, address);
	191	return;
	192	}
	193
	194	no_context:
	195	/* Are we prepared to handle this kernel fault? */
	196	if (fixup_exception(regs))
	197	return;
	198
	199	/*
	200	* Oops. The kernel tried to access some bad page. We'll have to
	201	* terminate things with extreme prejudice.
	202	*/
	203	bust_spinlocks(1);
	204
	205	pr_alert("Unable to handle kernel %s at virtual address %08lx",
	206	address < PAGE_SIZE ? "NULL pointer dereference" :
	207	"paging request", address);
	208	pr_alert("ea = %08lx, ra = %08lx, cause = %ld\n", regs->ea, regs->ra,
	209	cause);
	210	panic("Oops");
	211	return;
	212
	213	/*
	214	* We ran out of memory, or some other thing happened to us that made
	215	* us unable to handle the page fault gracefully.
	216	*/
	217	out_of_memory:
d8ed45c5	218	mmap_read_unlock(mm);
862674d4 LFT	219	if (!user_mode(regs))
	220	goto no_context;
	221	pagefault_out_of_memory();
	222	return;
	223
	224	do_sigbus:
d8ed45c5	225	mmap_read_unlock(mm);
862674d4 LFT	226
	227	/* Kernel mode? Handle exceptions or die */
	228	if (!user_mode(regs))
	229	goto no_context;
	230
	231	_exception(SIGBUS, regs, BUS_ADRERR, address);
	232	return;
	233
	234	vmalloc_fault:
	235	{
	236	/*
	237	* Synchronize this task's top level page-table
	238	* with the 'reference' page table.
	239	*
	240	* Do _not_ use "tsk" here. We might be inside
	241	* an interrupt in the middle of a task switch..
	242	*/
	243	int offset = pgd_index(address);
	244	pgd_t pgd, pgd_k;
9f4e7037	245	p4d_t p4d, p4d_k;
862674d4 LFT	246	pud_t pud, pud_k;
	247	pmd_t pmd, pmd_k;
	248	pte_t *pte_k;
	249
	250	pgd = pgd_current + offset;
	251	pgd_k = init_mm.pgd + offset;
	252
	253	if (!pgd_present(*pgd_k))
	254	goto no_context;
	255	set_pgd(pgd, *pgd_k);
	256
9f4e7037 MR	257	p4d = p4d_offset(pgd, address);
	258	p4d_k = p4d_offset(pgd_k, address);
	259	if (!p4d_present(*p4d_k))
	260	goto no_context;
	261	pud = pud_offset(p4d, address);
	262	pud_k = pud_offset(p4d_k, address);
862674d4 LFT	263	if (!pud_present(*pud_k))
	264	goto no_context;
	265	pmd = pmd_offset(pud, address);
	266	pmd_k = pmd_offset(pud_k, address);
	267	if (!pmd_present(*pmd_k))
	268	goto no_context;
	269	set_pmd(pmd, *pmd_k);
	270
	271	pte_k = pte_offset_kernel(pmd_k, address);
	272	if (!pte_present(*pte_k))
	273	goto no_context;
	274
195568a1	275	flush_tlb_kernel_page(address);
862674d4 LFT	276	return;
	277	}
	278	}