[mirror_ubuntu-artful-kernel.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/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/module.h>
#include <linux/uaccess.h>
#include <linux/ptrace.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;
	int fault;
	unsigned int flags = 0;

	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 (in_atomic() || !mm)
		goto bad_area_nosemaphore;

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

	if (!down_read_trylock(&mm->mmap_sem)) {
		if (!user_mode(regs) && !search_exception_tables(regs->ea))
			goto bad_area_nosemaphore;
		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;

	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;
	}

survive:
	/*
	 * 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, address, flags);
	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_MAJOR)
		tsk->maj_flt++;
	else
		tsk->min_flt++;

	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);

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:
	up_read(&mm->mmap_sem);
	if (is_global_init(tsk)) {
		yield();
		down_read(&mm->mmap_sem);
		goto survive;
	}
	if (!user_mode(regs))
		goto no_context;
	pagefault_out_of_memory();
	return;

do_sigbus:
	up_read(&mm->mmap_sem);

	/* 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;
		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);

		pud = pud_offset(pgd, address);
		pud_k = pud_offset(pgd_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_one(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>
	16	#include <linux/interrupt.h>
	17	#include <linux/kernel.h>
	18	#include <linux/errno.h>
	19	#include <linux/string.h>
	20	#include <linux/types.h>
	21	#include <linux/ptrace.h>
	22	#include <linux/mman.h>
	23	#include <linux/mm.h>
	24	#include <linux/module.h>
	25	#include <linux/uaccess.h>
	26	#include <linux/ptrace.h>
	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;
	49	int fault;
	50	unsigned int flags = 0;
	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	*/
80	if (in_atomic() \|\| !mm)
81	goto bad_area_nosemaphore;
82
83	if (user_mode(regs))
84	flags \|= FAULT_FLAG_USER;
85
86	if (!down_read_trylock(&mm->mmap_sem)) {
87	if (!user_mode(regs) && !search_exception_tables(regs->ea))
88	goto bad_area_nosemaphore;
89	down_read(&mm->mmap_sem);
90	}
91
92	vma = find_vma(mm, address);
93	if (!vma)
94	goto bad_area;
95	if (vma->vm_start <= address)
96	goto good_area;
97	if (!(vma->vm_flags & VM_GROWSDOWN))
98	goto bad_area;
99	if (expand_stack(vma, address))
100	goto bad_area;
101	/*
102	* Ok, we have a good vm_area for this memory access, so
103	* we can handle it..
104	*/
105	good_area:
106	code = SEGV_ACCERR;
107
108	switch (cause) {
109	case EXC_SUPERV_INSN_ACCESS:
110	goto bad_area;
111	case EXC_SUPERV_DATA_ACCESS:
112	goto bad_area;
113	case EXC_X_PROTECTION_FAULT:
114	if (!(vma->vm_flags & VM_EXEC))
115	goto bad_area;
116	break;
117	case EXC_R_PROTECTION_FAULT:
118	if (!(vma->vm_flags & VM_READ))
119	goto bad_area;
120	break;
121	case EXC_W_PROTECTION_FAULT:
122	if (!(vma->vm_flags & VM_WRITE))
123	goto bad_area;
124	flags = FAULT_FLAG_WRITE;
125	break;
126	}
127
128	survive:
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	*/
134	fault = handle_mm_fault(mm, vma, address, flags);
135	if (unlikely(fault & VM_FAULT_ERROR)) {
136	if (fault & VM_FAULT_OOM)
137	goto out_of_memory;
33692f27 LT	138	else if (fault & VM_FAULT_SIGSEGV)
33692f27 LT	139	goto bad_area;
862674d4 LFT	140	else if (fault & VM_FAULT_SIGBUS)
	141	goto do_sigbus;
	142	BUG();
	143	}
	144	if (fault & VM_FAULT_MAJOR)
	145	tsk->maj_flt++;
	146	else
	147	tsk->min_flt++;
	148
	149	up_read(&mm->mmap_sem);
	150	return;
	151
	152	/*
	153	* Something tried to access memory that isn't in our memory map..
	154	* Fix it, but check if it's kernel or user first..
	155	*/
	156	bad_area:
	157	up_read(&mm->mmap_sem);
	158
	159	bad_area_nosemaphore:
	160	/* User mode accesses just cause a SIGSEGV */
	161	if (user_mode(regs)) {
a3248d60 CLT	162	if (unhandled_signal(current, SIGSEGV) && printk_ratelimit()) {
	163	pr_info("%s: unhandled page fault (%d) at 0x%08lx, "
	164	"cause %ld\n", current->comm, SIGSEGV, address, cause);
	165	show_regs(regs);
	166	}
862674d4 LFT	167	_exception(SIGSEGV, regs, code, address);
	168	return;
	169	}
	170
	171	no_context:
	172	/* Are we prepared to handle this kernel fault? */
	173	if (fixup_exception(regs))
	174	return;
	175
	176	/*
	177	* Oops. The kernel tried to access some bad page. We'll have to
	178	* terminate things with extreme prejudice.
	179	*/
	180	bust_spinlocks(1);
	181
	182	pr_alert("Unable to handle kernel %s at virtual address %08lx",
	183	address < PAGE_SIZE ? "NULL pointer dereference" :
	184	"paging request", address);
	185	pr_alert("ea = %08lx, ra = %08lx, cause = %ld\n", regs->ea, regs->ra,
	186	cause);
	187	panic("Oops");
	188	return;
	189
	190	/*
	191	* We ran out of memory, or some other thing happened to us that made
	192	* us unable to handle the page fault gracefully.
	193	*/
	194	out_of_memory:
	195	up_read(&mm->mmap_sem);
	196	if (is_global_init(tsk)) {
	197	yield();
	198	down_read(&mm->mmap_sem);
	199	goto survive;
	200	}
	201	if (!user_mode(regs))
	202	goto no_context;
	203	pagefault_out_of_memory();
	204	return;
	205
	206	do_sigbus:
	207	up_read(&mm->mmap_sem);
	208
	209	/* Kernel mode? Handle exceptions or die */
	210	if (!user_mode(regs))
	211	goto no_context;
	212
	213	_exception(SIGBUS, regs, BUS_ADRERR, address);
	214	return;
	215
	216	vmalloc_fault:
	217	{
	218	/*
	219	* Synchronize this task's top level page-table
	220	* with the 'reference' page table.
	221	*
	222	* Do _not_ use "tsk" here. We might be inside
	223	* an interrupt in the middle of a task switch..
	224	*/
	225	int offset = pgd_index(address);
	226	pgd_t pgd, pgd_k;
	227	pud_t pud, pud_k;
	228	pmd_t pmd, pmd_k;
	229	pte_t *pte_k;
	230
231	pgd = pgd_current + offset;
232	pgd_k = init_mm.pgd + offset;
233
234	if (!pgd_present(*pgd_k))
235	goto no_context;
236	set_pgd(pgd, *pgd_k);
237
238	pud = pud_offset(pgd, address);
239	pud_k = pud_offset(pgd_k, address);
240	if (!pud_present(*pud_k))
241	goto no_context;
242	pmd = pmd_offset(pud, address);
243	pmd_k = pmd_offset(pud_k, address);
244	if (!pmd_present(*pmd_k))
245	goto no_context;
246	set_pmd(pmd, *pmd_k);
247
248	pte_k = pte_offset_kernel(pmd_k, address);
249	if (!pte_present(*pte_k))
250	goto no_context;
251
252	flush_tlb_one(address);
253	return;
254	}
255	}