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

/*
 * Copyright (C) 2009 Wind River Systems Inc
 *   Implemented by [email protected] and [email protected]
 *
 * 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 <linux/perf_event.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;

	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);

retry:
	vma = lock_mm_and_find_vma(mm, address, regs);
	if (!vma)
		goto bad_area_nosemaphore;
/*
 * Ok, we have a good vm_area for this memory access, so
 * we can handle it..
 */
	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, regs);

	if (fault_signal_pending(fault, regs)) {
		if (!user_mode(regs))
			goto no_context;
		return;
	}

	/* The fault is fully completed (including releasing mmap lock) */
	if (fault & VM_FAULT_COMPLETED)
		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();
	}

	if (fault & VM_FAULT_RETRY) {
		flags |= FAULT_FLAG_TRIED;

		/*
		 * No need to mmap_read_unlock(mm) 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 [email protected] and [email protected]
	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>
4487dcf9	27	#include <linux/perf_event.h>
862674d4 LFT	28
	29	#include <asm/mmu_context.h>
	30	#include <asm/traps.h>
	31
	32	#define EXC_SUPERV_INSN_ACCESS 9 /* Supervisor only instruction address */
	33	#define EXC_SUPERV_DATA_ACCESS 11 /* Supervisor only data address */
	34	#define EXC_X_PROTECTION_FAULT 13 /* TLB permission violation (x) */
	35	#define EXC_R_PROTECTION_FAULT 14 /* TLB permission violation (r) */
	36	#define EXC_W_PROTECTION_FAULT 15 /* TLB permission violation (w) */
	37
	38	/*
	39	* This routine handles page faults. It determines the address,
	40	* and the problem, and then passes it off to one of the appropriate
	41	* routines.
	42	*/
	43	asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long cause,
	44	unsigned long address)
	45	{
	46	struct vm_area_struct *vma = NULL;
	47	struct task_struct *tsk = current;
	48	struct mm_struct *mm = tsk->mm;
	49	int code = SEGV_MAPERR;
50a7ca3c	50	vm_fault_t fault;
dde16072	51	unsigned int flags = FAULT_FLAG_DEFAULT;
862674d4 LFT	52
	53	cause >>= 2;
	54
	55	/* Restart the instruction */
	56	regs->ea -= 4;
	57
	58	/*
	59	* We fault-in kernel-space virtual memory on-demand. The
	60	* 'reference' page table is init_mm.pgd.
	61	*
	62	* NOTE! We MUST NOT take any locks for this case. We may
	63	* be in an interrupt or a critical region, and should
	64	* only copy the information from the master page table,
	65	* nothing more.
	66	*/
	67	if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) {
	68	if (user_mode(regs))
	69	goto bad_area_nosemaphore;
	70	else
	71	goto vmalloc_fault;
	72	}
	73
	74	if (unlikely(address >= TASK_SIZE))
	75	goto bad_area_nosemaphore;
	76
	77	/*
	78	* If we're in an interrupt or have no user
	79	* context, we must not take the fault..
	80	*/
70ffdb93	81	if (faulthandler_disabled() \|\| !mm)
862674d4 LFT	82	goto bad_area_nosemaphore;
	83
	84	if (user_mode(regs))
	85	flags \|= FAULT_FLAG_USER;
	86
4487dcf9 PX	87	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
4487dcf9 PX	88
96f3a5cc	89	retry:
a050ba1e	90	vma = lock_mm_and_find_vma(mm, address, regs);
862674d4	91	if (!vma)
a050ba1e	92	goto bad_area_nosemaphore;
862674d4 LFT	93	/*
	94	* Ok, we have a good vm_area for this memory access, so
	95	* we can handle it..
	96	*/
862674d4 LFT	97	code = SEGV_ACCERR;
	98
	99	switch (cause) {
	100	case EXC_SUPERV_INSN_ACCESS:
	101	goto bad_area;
	102	case EXC_SUPERV_DATA_ACCESS:
	103	goto bad_area;
	104	case EXC_X_PROTECTION_FAULT:
	105	if (!(vma->vm_flags & VM_EXEC))
	106	goto bad_area;
	107	break;
	108	case EXC_R_PROTECTION_FAULT:
	109	if (!(vma->vm_flags & VM_READ))
	110	goto bad_area;
	111	break;
	112	case EXC_W_PROTECTION_FAULT:
	113	if (!(vma->vm_flags & VM_WRITE))
	114	goto bad_area;
	115	flags = FAULT_FLAG_WRITE;
	116	break;
	117	}
	118
862674d4 LFT	119	/*
	120	* If for any reason at all we couldn't handle the fault,
	121	* make sure we exit gracefully rather than endlessly redo
	122	* the fault.
	123	*/
4487dcf9	124	fault = handle_mm_fault(vma, address, flags, regs);
96f3a5cc	125
e902e508 AV	126	if (fault_signal_pending(fault, regs)) {
	127	if (!user_mode(regs))
	128	goto no_context;
96f3a5cc	129	return;
e902e508	130	}
96f3a5cc	131
d9272525 PX	132	/* The fault is fully completed (including releasing mmap lock) */
	133	if (fault & VM_FAULT_COMPLETED)
	134	return;
	135
862674d4 LFT	136	if (unlikely(fault & VM_FAULT_ERROR)) {
	137	if (fault & VM_FAULT_OOM)
	138	goto out_of_memory;
33692f27 LT	139	else if (fault & VM_FAULT_SIGSEGV)
33692f27 LT	140	goto bad_area;
862674d4 LFT	141	else if (fault & VM_FAULT_SIGBUS)
	142	goto do_sigbus;
	143	BUG();
	144	}
96f3a5cc	145
36ef159f QZ	146	if (fault & VM_FAULT_RETRY) {
	147	flags \|= FAULT_FLAG_TRIED;
	148
	149	/*
	150	* No need to mmap_read_unlock(mm) as we would
	151	* have already released it in __lock_page_or_retry
	152	* in mm/filemap.c.
	153	*/
	154
	155	goto retry;
96f3a5cc	156	}
862674d4	157
d8ed45c5	158	mmap_read_unlock(mm);
862674d4 LFT	159	return;
	160
	161	/*
	162	* Something tried to access memory that isn't in our memory map..
	163	* Fix it, but check if it's kernel or user first..
	164	*/
	165	bad_area:
d8ed45c5	166	mmap_read_unlock(mm);
862674d4 LFT	167
	168	bad_area_nosemaphore:
	169	/* User mode accesses just cause a SIGSEGV */
	170	if (user_mode(regs)) {
a3248d60 CLT	171	if (unhandled_signal(current, SIGSEGV) && printk_ratelimit()) {
	172	pr_info("%s: unhandled page fault (%d) at 0x%08lx, "
	173	"cause %ld\n", current->comm, SIGSEGV, address, cause);
	174	show_regs(regs);
	175	}
862674d4 LFT	176	_exception(SIGSEGV, regs, code, address);
	177	return;
	178	}
	179
	180	no_context:
	181	/* Are we prepared to handle this kernel fault? */
	182	if (fixup_exception(regs))
	183	return;
	184
	185	/*
	186	* Oops. The kernel tried to access some bad page. We'll have to
	187	* terminate things with extreme prejudice.
	188	*/
	189	bust_spinlocks(1);
	190
	191	pr_alert("Unable to handle kernel %s at virtual address %08lx",
	192	address < PAGE_SIZE ? "NULL pointer dereference" :
	193	"paging request", address);
	194	pr_alert("ea = %08lx, ra = %08lx, cause = %ld\n", regs->ea, regs->ra,
	195	cause);
	196	panic("Oops");
	197	return;
	198
	199	/*
	200	* We ran out of memory, or some other thing happened to us that made
	201	* us unable to handle the page fault gracefully.
	202	*/
	203	out_of_memory:
d8ed45c5	204	mmap_read_unlock(mm);
862674d4 LFT	205	if (!user_mode(regs))
	206	goto no_context;
	207	pagefault_out_of_memory();
	208	return;
	209
	210	do_sigbus:
d8ed45c5	211	mmap_read_unlock(mm);
862674d4 LFT	212
	213	/* Kernel mode? Handle exceptions or die */
	214	if (!user_mode(regs))
	215	goto no_context;
	216
	217	_exception(SIGBUS, regs, BUS_ADRERR, address);
	218	return;
	219
	220	vmalloc_fault:
	221	{
	222	/*
	223	* Synchronize this task's top level page-table
	224	* with the 'reference' page table.
	225	*
	226	* Do _not_ use "tsk" here. We might be inside
	227	* an interrupt in the middle of a task switch..
	228	*/
	229	int offset = pgd_index(address);
	230	pgd_t pgd, pgd_k;
9f4e7037	231	p4d_t p4d, p4d_k;
862674d4 LFT	232	pud_t pud, pud_k;
	233	pmd_t pmd, pmd_k;
	234	pte_t *pte_k;
	235
	236	pgd = pgd_current + offset;
	237	pgd_k = init_mm.pgd + offset;
	238
	239	if (!pgd_present(*pgd_k))
	240	goto no_context;
	241	set_pgd(pgd, *pgd_k);
	242
9f4e7037 MR	243	p4d = p4d_offset(pgd, address);
	244	p4d_k = p4d_offset(pgd_k, address);
	245	if (!p4d_present(*p4d_k))
	246	goto no_context;
	247	pud = pud_offset(p4d, address);
	248	pud_k = pud_offset(p4d_k, address);
862674d4 LFT	249	if (!pud_present(*pud_k))
	250	goto no_context;
	251	pmd = pmd_offset(pud, address);
	252	pmd_k = pmd_offset(pud_k, address);
	253	if (!pmd_present(*pmd_k))
	254	goto no_context;
	255	set_pmd(pmd, *pmd_k);
	256
	257	pte_k = pte_offset_kernel(pmd_k, address);
	258	if (!pte_present(*pte_k))
	259	goto no_context;
	260
195568a1	261	flush_tlb_kernel_page(address);
862674d4 LFT	262	return;
	263	}
	264	}