[linux-2.6-block.git] / arch / mips / mm / fault.c

/*
 * 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.
 *
 * Copyright (C) 1995 - 2000 by Ralf Baechle
 */
#include <linux/context_tracking.h>
#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/smp.h>
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/perf_event.h>

#include <asm/branch.h>
#include <asm/mmu_context.h>
#include <asm/uaccess.h>
#include <asm/ptrace.h>
#include <asm/highmem.h>		/* For VMALLOC_END */
#include <linux/kdebug.h>

/*
 * This routine handles page faults.  It determines the address,
 * and the problem, and then passes it off to one of the appropriate
 * routines.
 */
static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
	unsigned long address)
{
	struct vm_area_struct * vma = NULL;
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	const int field = sizeof(unsigned long) * 2;
	siginfo_t info;
	int fault;
	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

#if 0
	printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
	       current->comm, current->pid, field, address, write,
	       field, regs->cp0_epc);
#endif

#ifdef CONFIG_KPROBES
	/*
	 * This is to notify the fault handler of the kprobes.	The
	 * exception code is redundant as it is also carried in REGS,
	 * but we pass it anyhow.
	 */
	if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
		       (regs->cp0_cause >> 2) & 0x1f, SIGSEGV) == NOTIFY_STOP)
		return;
#endif

	info.si_code = SEGV_MAPERR;

	/*
	 * 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.
	 */
#ifdef CONFIG_64BIT
# define VMALLOC_FAULT_TARGET no_context
#else
# define VMALLOC_FAULT_TARGET vmalloc_fault
#endif

	if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
		goto VMALLOC_FAULT_TARGET;
#ifdef MODULE_START
	if (unlikely(address >= MODULE_START && address < MODULE_END))
		goto VMALLOC_FAULT_TARGET;
#endif

	/*
	 * 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;
retry:
	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:
	info.si_code = SEGV_ACCERR;

	if (write) {
		if (!(vma->vm_flags & VM_WRITE))
			goto bad_area;
		flags |= FAULT_FLAG_WRITE;
	} else {
		if (cpu_has_rixi) {
			if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
#if 0
				pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n",
					  raw_smp_processor_id(),
					  current->comm, current->pid,
					  field, address, write,
					  field, regs->cp0_epc);
#endif
				goto bad_area;
			}
			if (!(vma->vm_flags & VM_READ)) {
#if 0
				pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n",
					  raw_smp_processor_id(),
					  current->comm, current->pid,
					  field, address, write,
					  field, regs->cp0_epc);
#endif
				goto bad_area;
			}
		} else {
			if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
				goto bad_area;
		}
	}

	/*
	 * 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 ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
		return;

	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
	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 (flags & FAULT_FLAG_ALLOW_RETRY) {
		if (fault & VM_FAULT_MAJOR) {
			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
						  regs, address);
			tsk->maj_flt++;
		} else {
			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
						  regs, address);
			tsk->min_flt++;
		}
		if (fault & VM_FAULT_RETRY) {
			flags &= ~FAULT_FLAG_ALLOW_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;
		}
	}

	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)) {
		tsk->thread.cp0_badvaddr = address;
		tsk->thread.error_code = write;
#if 0
		printk("do_page_fault() #2: sending SIGSEGV to %s for "
		       "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
		       tsk->comm,
		       write ? "write access to" : "read access from",
		       field, address,
		       field, (unsigned long) regs->cp0_epc,
		       field, (unsigned long) regs->regs[31]);
#endif
		info.si_signo = SIGSEGV;
		info.si_errno = 0;
		/* info.si_code has been set above */
		info.si_addr = (void __user *) address;
		force_sig_info(SIGSEGV, &info, tsk);
		return;
	}

no_context:
	/* Are we prepared to handle this kernel fault?	 */
	if (fixup_exception(regs)) {
		current->thread.cp0_baduaddr = address;
		return;
	}

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

	printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
	       "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
	       raw_smp_processor_id(), field, address, field, regs->cp0_epc,
	       field,  regs->regs[31]);
	die("Oops", regs);

out_of_memory:
	/*
	 * We ran out of memory, call the OOM killer, and return the userspace
	 * (which will retry the fault, or kill us if we got oom-killed).
	 */
	up_read(&mm->mmap_sem);
	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;
	else
	/*
	 * Send a sigbus, regardless of whether we were in kernel
	 * or user mode.
	 */
#if 0
		printk("do_page_fault() #3: sending SIGBUS to %s for "
		       "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
		       tsk->comm,
		       write ? "write access to" : "read access from",
		       field, address,
		       field, (unsigned long) regs->cp0_epc,
		       field, (unsigned long) regs->regs[31]);
#endif
	tsk->thread.cp0_badvaddr = address;
	info.si_signo = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRERR;
	info.si_addr = (void __user *) address;
	force_sig_info(SIGBUS, &info, tsk);

	return;
#ifndef CONFIG_64BIT
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_offset(address);
		pgd_t *pgd, *pgd_k;
		pud_t *pud, *pud_k;
		pmd_t *pmd, *pmd_k;
		pte_t *pte_k;

		pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + 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;
		return;
	}
#endif
}

asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
	unsigned long write, unsigned long address)
{
	enum ctx_state prev_state;

	prev_state = exception_enter();
	__do_page_fault(regs, write, address);
	exception_exit(prev_state);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* This file is subject to the terms and conditions of the GNU General Public
	3	* License. See the file "COPYING" in the main directory of this archive
	4	* for more details.
	5	*
	6	* Copyright (C) 1995 - 2000 by Ralf Baechle
	7	*/
c3fc5cd5	8	#include <linux/context_tracking.h>
1da177e4 LT	9	#include <linux/signal.h>
	10	#include <linux/sched.h>
	11	#include <linux/interrupt.h>
	12	#include <linux/kernel.h>
	13	#include <linux/errno.h>
	14	#include <linux/string.h>
	15	#include <linux/types.h>
	16	#include <linux/ptrace.h>
	17	#include <linux/mman.h>
	18	#include <linux/mm.h>
	19	#include <linux/smp.h>
1da177e4	20	#include <linux/module.h>
c1bf207d	21	#include <linux/kprobes.h>
7f788d2d	22	#include <linux/perf_event.h>
1da177e4 LT	23
	24	#include <asm/branch.h>
	25	#include <asm/mmu_context.h>
1da177e4 LT	26	#include <asm/uaccess.h>
1da177e4 LT	27	#include <asm/ptrace.h>
16033d61	28	#include <asm/highmem.h> /* For VMALLOC_END */
c1bf207d	29	#include <linux/kdebug.h>
1da177e4 LT	30
	31	/*
	32	* This routine handles page faults. It determines the address,
	33	* and the problem, and then passes it off to one of the appropriate
	34	* routines.
	35	*/
c3fc5cd5 RB	36	static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
c3fc5cd5 RB	37	unsigned long address)
1da177e4 LT	38	{
	39	struct vm_area_struct * vma = NULL;
	40	struct task_struct *tsk = current;
	41	struct mm_struct *mm = tsk->mm;
	42	const int field = sizeof(unsigned long) * 2;
	43	siginfo_t info;
83c54070	44	int fault;
759496ba	45	unsigned int flags = FAULT_FLAG_ALLOW_RETRY \| FAULT_FLAG_KILLABLE;
1da177e4 LT	46
1da177e4 LT	47	#if 0
d6f70360	48	printk("Cpu%d[%s:%d:%0lx:%ld:%0lx]\n", raw_smp_processor_id(),
1da177e4 LT	49	current->comm, current->pid, field, address, write,
	50	field, regs->cp0_epc);
	51	#endif
	52
c1bf207d DD	53	#ifdef CONFIG_KPROBES
c1bf207d DD	54	/*
70342287	55	* This is to notify the fault handler of the kprobes. The
c1bf207d DD	56	* exception code is redundant as it is also carried in REGS,
	57	* but we pass it anyhow.
	58	*/
	59	if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
	60	(regs->cp0_cause >> 2) & 0x1f, SIGSEGV) == NOTIFY_STOP)
	61	return;
	62	#endif
	63
1da177e4 LT	64	info.si_code = SEGV_MAPERR;
	65
	66	/*
	67	* We fault-in kernel-space virtual memory on-demand. The
	68	* 'reference' page table is init_mm.pgd.
	69	*
	70	* NOTE! We MUST NOT take any locks for this case. We may
	71	* be in an interrupt or a critical region, and should
	72	* only copy the information from the master page table,
	73	* nothing more.
	74	*/
2ca2ebfd DD	75	#ifdef CONFIG_64BIT
	76	# define VMALLOC_FAULT_TARGET no_context
	77	#else
	78	# define VMALLOC_FAULT_TARGET vmalloc_fault
	79	#endif
	80
16033d61	81	if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
2ca2ebfd	82	goto VMALLOC_FAULT_TARGET;
656be92f AN	83	#ifdef MODULE_START
656be92f AN	84	if (unlikely(address >= MODULE_START && address < MODULE_END))
2ca2ebfd	85	goto VMALLOC_FAULT_TARGET;
656be92f	86	#endif
1da177e4 LT	87
	88	/*
	89	* If we're in an interrupt or have no user
	90	* context, we must not take the fault..
	91	*/
	92	if (in_atomic() \|\| !mm)
	93	goto bad_area_nosemaphore;
	94
759496ba JW	95	if (user_mode(regs))
759496ba JW	96	flags \|= FAULT_FLAG_USER;
43ca4957	97	retry:
1da177e4 LT	98	down_read(&mm->mmap_sem);
	99	vma = find_vma(mm, address);
	100	if (!vma)
	101	goto bad_area;
	102	if (vma->vm_start <= address)
	103	goto good_area;
	104	if (!(vma->vm_flags & VM_GROWSDOWN))
	105	goto bad_area;
	106	if (expand_stack(vma, address))
	107	goto bad_area;
	108	/*
	109	* Ok, we have a good vm_area for this memory access, so
	110	* we can handle it..
	111	*/
	112	good_area:
	113	info.si_code = SEGV_ACCERR;
	114
	115	if (write) {
	116	if (!(vma->vm_flags & VM_WRITE))
	117	goto bad_area;
759496ba	118	flags \|= FAULT_FLAG_WRITE;
1da177e4	119	} else {
05857c64	120	if (cpu_has_rixi) {
6dd9344c DD	121	if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
	122	#if 0
	123	pr_notice("Cpu%d[%s:%d:%0lx:%ld:%0lx] XI violation\n",
	124	raw_smp_processor_id(),
	125	current->comm, current->pid,
	126	field, address, write,
	127	field, regs->cp0_epc);
	128	#endif
	129	goto bad_area;
	130	}
	131	if (!(vma->vm_flags & VM_READ)) {
	132	#if 0
	133	pr_notice("Cpu%d[%s:%d:%0lx:%ld:%0lx] RI violation\n",
	134	raw_smp_processor_id(),
	135	current->comm, current->pid,
	136	field, address, write,
	137	field, regs->cp0_epc);
	138	#endif
	139	goto bad_area;
	140	}
	141	} else {
	142	if (!(vma->vm_flags & (VM_READ \| VM_WRITE \| VM_EXEC)))
	143	goto bad_area;
	144	}
1da177e4 LT	145	}
1da177e4 LT	146
1da177e4 LT	147	/*
	148	* If for any reason at all we couldn't handle the fault,
	149	* make sure we exit gracefully rather than endlessly redo
	150	* the fault.
	151	*/
43ca4957 KC	152	fault = handle_mm_fault(mm, vma, address, flags);
	153
	154	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
	155	return;
	156
a8b0ca17	157	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
83c54070 NP	158	if (unlikely(fault & VM_FAULT_ERROR)) {
	159	if (fault & VM_FAULT_OOM)
	160	goto out_of_memory;
33692f27 LT	161	else if (fault & VM_FAULT_SIGSEGV)
33692f27 LT	162	goto bad_area;
83c54070 NP	163	else if (fault & VM_FAULT_SIGBUS)
83c54070 NP	164	goto do_sigbus;
1da177e4 LT	165	BUG();
1da177e4 LT	166	}
43ca4957 KC	167	if (flags & FAULT_FLAG_ALLOW_RETRY) {
	168	if (fault & VM_FAULT_MAJOR) {
	169	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
	170	regs, address);
	171	tsk->maj_flt++;
	172	} else {
	173	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
	174	regs, address);
	175	tsk->min_flt++;
	176	}
	177	if (fault & VM_FAULT_RETRY) {
	178	flags &= ~FAULT_FLAG_ALLOW_RETRY;
45cac65b	179	flags \|= FAULT_FLAG_TRIED;
43ca4957 KC	180
	181	/*
	182	* No need to up_read(&mm->mmap_sem) as we would
	183	* have already released it in __lock_page_or_retry
	184	* in mm/filemap.c.
	185	*/
	186
	187	goto retry;
	188	}
7f788d2d	189	}
1da177e4 LT	190
	191	up_read(&mm->mmap_sem);
	192	return;
	193
	194	/*
	195	* Something tried to access memory that isn't in our memory map..
	196	* Fix it, but check if it's kernel or user first..
	197	*/
	198	bad_area:
	199	up_read(&mm->mmap_sem);
	200
	201	bad_area_nosemaphore:
	202	/* User mode accesses just cause a SIGSEGV */
	203	if (user_mode(regs)) {
	204	tsk->thread.cp0_badvaddr = address;
	205	tsk->thread.error_code = write;
	206	#if 0
	207	printk("do_page_fault() #2: sending SIGSEGV to %s for "
	208	"invalid %s\n%0lx (epc == %0lx, ra == %0*lx)\n",
	209	tsk->comm,
	210	write ? "write access to" : "read access from",
	211	field, address,
	212	field, (unsigned long) regs->cp0_epc,
	213	field, (unsigned long) regs->regs[31]);
	214	#endif
	215	info.si_signo = SIGSEGV;
	216	info.si_errno = 0;
	217	/* info.si_code has been set above */
fe00f943	218	info.si_addr = (void __user *) address;
1da177e4 LT	219	force_sig_info(SIGSEGV, &info, tsk);
	220	return;
	221	}
	222
	223	no_context:
70342287	224	/* Are we prepared to handle this kernel fault? */
1da177e4 LT	225	if (fixup_exception(regs)) {
	226	current->thread.cp0_baduaddr = address;
	227	return;
	228	}
	229
	230	/*
	231	* Oops. The kernel tried to access some bad page. We'll have to
	232	* terminate things with extreme prejudice.
	233	*/
1da177e4 LT	234	bust_spinlocks(1);
	235
	236	printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
	237	"virtual address %0lx, epc == %0lx, ra == %0*lx\n",
d6f70360	238	raw_smp_processor_id(), field, address, field, regs->cp0_epc,
1da177e4 LT	239	field, regs->regs[31]);
	240	die("Oops", regs);
	241
1da177e4	242	out_of_memory:
c7c1e384 RB	243	/*
	244	* We ran out of memory, call the OOM killer, and return the userspace
	245	* (which will retry the fault, or kill us if we got oom-killed).
	246	*/
a887b4da	247	up_read(&mm->mmap_sem);
87134102 JW	248	if (!user_mode(regs))
87134102 JW	249	goto no_context;
c7c1e384 RB	250	pagefault_out_of_memory();
c7c1e384 RB	251	return;
1da177e4 LT	252
	253	do_sigbus:
	254	up_read(&mm->mmap_sem);
	255
	256	/* Kernel mode? Handle exceptions or die */
	257	if (!user_mode(regs))
	258	goto no_context;
41c594ab	259	else
1da177e4 LT	260	/*
	261	* Send a sigbus, regardless of whether we were in kernel
	262	* or user mode.
	263	*/
41c594ab RB	264	#if 0
	265	printk("do_page_fault() #3: sending SIGBUS to %s for "
	266	"invalid %s\n%0lx (epc == %0lx, ra == %0*lx)\n",
	267	tsk->comm,
	268	write ? "write access to" : "read access from",
	269	field, address,
	270	field, (unsigned long) regs->cp0_epc,
	271	field, (unsigned long) regs->regs[31]);
	272	#endif
1da177e4 LT	273	tsk->thread.cp0_badvaddr = address;
	274	info.si_signo = SIGBUS;
	275	info.si_errno = 0;
	276	info.si_code = BUS_ADRERR;
fe00f943	277	info.si_addr = (void __user *) address;
1da177e4 LT	278	force_sig_info(SIGBUS, &info, tsk);
	279
	280	return;
2ca2ebfd	281	#ifndef CONFIG_64BIT
1da177e4 LT	282	vmalloc_fault:
	283	{
	284	/*
	285	* Synchronize this task's top level page-table
	286	* with the 'reference' page table.
	287	*
	288	* Do _not_ use "tsk" here. We might be inside
	289	* an interrupt in the middle of a task switch..
	290	*/
	291	int offset = __pgd_offset(address);
	292	pgd_t pgd, pgd_k;
c6e8b587	293	pud_t pud, pud_k;
1da177e4 LT	294	pmd_t pmd, pmd_k;
	295	pte_t *pte_k;
	296
d6f70360	297	pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
1da177e4 LT	298	pgd_k = init_mm.pgd + offset;
	299
	300	if (!pgd_present(*pgd_k))
	301	goto no_context;
	302	set_pgd(pgd, *pgd_k);
	303
c6e8b587 RB	304	pud = pud_offset(pgd, address);
	305	pud_k = pud_offset(pgd_k, address);
	306	if (!pud_present(*pud_k))
	307	goto no_context;
	308
	309	pmd = pmd_offset(pud, address);
	310	pmd_k = pmd_offset(pud_k, address);
1da177e4 LT	311	if (!pmd_present(*pmd_k))
	312	goto no_context;
	313	set_pmd(pmd, *pmd_k);
	314
	315	pte_k = pte_offset_kernel(pmd_k, address);
	316	if (!pte_present(*pte_k))
	317	goto no_context;
	318	return;
	319	}
2ca2ebfd	320	#endif
1da177e4	321	}
c3fc5cd5 RB	322
	323	asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
	324	unsigned long write, unsigned long address)
	325	{
	326	enum ctx_state prev_state;
	327
	328	prev_state = exception_enter();
	329	__do_page_fault(regs, write, address);
	330	exception_exit(prev_state);
	331	}