[mirror_ubuntu-artful-kernel.git] / arch / m68k / mm / fault.c

/*
 *  linux/arch/m68k/mm/fault.c
 *
 *  Copyright (C) 1995  Hamish Macdonald
 */

#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/uaccess.h>

#include <asm/setup.h>
#include <asm/traps.h>
#include <asm/pgalloc.h>

extern void die_if_kernel(char *, struct pt_regs *, long);

int send_fault_sig(struct pt_regs *regs)
{
	siginfo_t siginfo = { 0, 0, 0, };

	siginfo.si_signo = current->thread.signo;
	siginfo.si_code = current->thread.code;
	siginfo.si_addr = (void *)current->thread.faddr;
	pr_debug("send_fault_sig: %p,%d,%d\n", siginfo.si_addr,
		 siginfo.si_signo, siginfo.si_code);

	if (user_mode(regs)) {
		force_sig_info(siginfo.si_signo,
			       &siginfo, current);
	} else {
		if (handle_kernel_fault(regs))
			return -1;

		//if (siginfo.si_signo == SIGBUS)
		//	force_sig_info(siginfo.si_signo,
		//		       &siginfo, current);

		/*
		 * Oops. The kernel tried to access some bad page. We'll have to
		 * terminate things with extreme prejudice.
		 */
		if ((unsigned long)siginfo.si_addr < PAGE_SIZE)
			pr_alert("Unable to handle kernel NULL pointer dereference");
		else
			pr_alert("Unable to handle kernel access");
		pr_cont(" at virtual address %p\n", siginfo.si_addr);
		die_if_kernel("Oops", regs, 0 /*error_code*/);
		do_exit(SIGKILL);
	}

	return 1;
}

/*
 * This routine handles page faults.  It determines the problem, and
 * then passes it off to one of the appropriate routines.
 *
 * error_code:
 *	bit 0 == 0 means no page found, 1 means protection fault
 *	bit 1 == 0 means read, 1 means write
 *
 * If this routine detects a bad access, it returns 1, otherwise it
 * returns 0.
 */
int do_page_fault(struct pt_regs *regs, unsigned long address,
			      unsigned long error_code)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct * vma;
	int fault;
	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

	pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
		regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);

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

	if (user_mode(regs))
		flags |= FAULT_FLAG_USER;
retry:
	down_read(&mm->mmap_sem);

	vma = find_vma(mm, address);
	if (!vma)
		goto map_err;
	if (vma->vm_flags & VM_IO)
		goto acc_err;
	if (vma->vm_start <= address)
		goto good_area;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		goto map_err;
	if (user_mode(regs)) {
		/* Accessing the stack below usp is always a bug.  The
		   "+ 256" is there due to some instructions doing
		   pre-decrement on the stack and that doesn't show up
		   until later.  */
		if (address + 256 < rdusp())
			goto map_err;
	}
	if (expand_stack(vma, address))
		goto map_err;

/*
 * Ok, we have a good vm_area for this memory access, so
 * we can handle it..
 */
good_area:
	pr_debug("do_page_fault: good_area\n");
	switch (error_code & 3) {
		default:	/* 3: write, present */
			/* fall through */
		case 2:		/* write, not present */
			if (!(vma->vm_flags & VM_WRITE))
				goto acc_err;
			flags |= FAULT_FLAG_WRITE;
			break;
		case 1:		/* read, present */
			goto acc_err;
		case 0:		/* read, not present */
			if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
				goto acc_err;
	}

	/*
	 * 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);
	pr_debug("handle_mm_fault returns %d\n", fault);

	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
		return 0;

	if (unlikely(fault & VM_FAULT_ERROR)) {
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGSEGV)
			goto map_err;
		else if (fault & VM_FAULT_SIGBUS)
			goto bus_err;
		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) {
			/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
			 * of starvation. */
			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 0;

/*
 * 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 (!user_mode(regs))
		goto no_context;
	pagefault_out_of_memory();
	return 0;

no_context:
	current->thread.signo = SIGBUS;
	current->thread.faddr = address;
	return send_fault_sig(regs);

bus_err:
	current->thread.signo = SIGBUS;
	current->thread.code = BUS_ADRERR;
	current->thread.faddr = address;
	goto send_sig;

map_err:
	current->thread.signo = SIGSEGV;
	current->thread.code = SEGV_MAPERR;
	current->thread.faddr = address;
	goto send_sig;

acc_err:
	current->thread.signo = SIGSEGV;
	current->thread.code = SEGV_ACCERR;
	current->thread.faddr = address;

send_sig:
	up_read(&mm->mmap_sem);
	return send_fault_sig(regs);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/arch/m68k/mm/fault.c
	3	*
	4	* Copyright (C) 1995 Hamish Macdonald
	5	*/
	6
	7	#include <linux/mman.h>
	8	#include <linux/mm.h>
	9	#include <linux/kernel.h>
	10	#include <linux/ptrace.h>
	11	#include <linux/interrupt.h>
	12	#include <linux/module.h>
70ffdb93	13	#include <linux/uaccess.h>
1da177e4 LT	14
	15	#include <asm/setup.h>
	16	#include <asm/traps.h>
1da177e4 LT	17	#include <asm/pgalloc.h>
	18
	19	extern void die_if_kernel(char , struct pt_regs , long);
1da177e4 LT	20
	21	int send_fault_sig(struct pt_regs *regs)
	22	{
	23	siginfo_t siginfo = { 0, 0, 0, };
	24
	25	siginfo.si_signo = current->thread.signo;
	26	siginfo.si_code = current->thread.code;
	27	siginfo.si_addr = (void *)current->thread.faddr;
8e398f63 GU	28	pr_debug("send_fault_sig: %p,%d,%d\n", siginfo.si_addr,
8e398f63 GU	29	siginfo.si_signo, siginfo.si_code);
1da177e4 LT	30
	31	if (user_mode(regs)) {
	32	force_sig_info(siginfo.si_signo,
	33	&siginfo, current);
	34	} else {
dcdf3a29	35	if (handle_kernel_fault(regs))
1da177e4	36	return -1;
1da177e4 LT	37
	38	//if (siginfo.si_signo == SIGBUS)
	39	// force_sig_info(siginfo.si_signo,
	40	// &siginfo, current);
	41
	42	/*
	43	* Oops. The kernel tried to access some bad page. We'll have to
	44	* terminate things with extreme prejudice.
	45	*/
	46	if ((unsigned long)siginfo.si_addr < PAGE_SIZE)
8e398f63	47	pr_alert("Unable to handle kernel NULL pointer dereference");
1da177e4	48	else
8e398f63 GU	49	pr_alert("Unable to handle kernel access");
8e398f63 GU	50	pr_cont(" at virtual address %p\n", siginfo.si_addr);
1da177e4 LT	51	die_if_kernel("Oops", regs, 0 /error_code/);
	52	do_exit(SIGKILL);
	53	}
	54
	55	return 1;
	56	}
	57
	58	/*
	59	* This routine handles page faults. It determines the problem, and
	60	* then passes it off to one of the appropriate routines.
	61	*
	62	* error_code:
	63	* bit 0 == 0 means no page found, 1 means protection fault
	64	* bit 1 == 0 means read, 1 means write
	65	*
	66	* If this routine detects a bad access, it returns 1, otherwise it
	67	* returns 0.
	68	*/
	69	int do_page_fault(struct pt_regs *regs, unsigned long address,
	70	unsigned long error_code)
	71	{
	72	struct mm_struct *mm = current->mm;
	73	struct vm_area_struct * vma;
b637a6b1 KC	74	int fault;
b637a6b1 KC	75	unsigned int flags = FAULT_FLAG_ALLOW_RETRY \| FAULT_FLAG_KILLABLE;
1da177e4	76
8e398f63	77	pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
4e25c0e9	78	regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);
1da177e4 LT	79
	80	/*
	81	* If we're in an interrupt or have no user
	82	* context, we must not take the fault..
	83	*/
70ffdb93	84	if (faulthandler_disabled() \|\| !mm)
1da177e4 LT	85	goto no_context;
1da177e4 LT	86
759496ba JW	87	if (user_mode(regs))
759496ba JW	88	flags \|= FAULT_FLAG_USER;
b637a6b1	89	retry:
1da177e4 LT	90	down_read(&mm->mmap_sem);
	91
	92	vma = find_vma(mm, address);
	93	if (!vma)
	94	goto map_err;
	95	if (vma->vm_flags & VM_IO)
	96	goto acc_err;
	97	if (vma->vm_start <= address)
	98	goto good_area;
	99	if (!(vma->vm_flags & VM_GROWSDOWN))
	100	goto map_err;
	101	if (user_mode(regs)) {
	102	/* Accessing the stack below usp is always a bug. The
	103	"+ 256" is there due to some instructions doing
	104	pre-decrement on the stack and that doesn't show up
	105	until later. */
	106	if (address + 256 < rdusp())
	107	goto map_err;
	108	}
	109	if (expand_stack(vma, address))
	110	goto map_err;
	111
	112	/*
	113	* Ok, we have a good vm_area for this memory access, so
	114	* we can handle it..
	115	*/
	116	good_area:
8e398f63	117	pr_debug("do_page_fault: good_area\n");
1da177e4 LT	118	switch (error_code & 3) {
	119	default: /* 3: write, present */
	120	/* fall through */
	121	case 2: /* write, not present */
	122	if (!(vma->vm_flags & VM_WRITE))
	123	goto acc_err;
b637a6b1	124	flags \|= FAULT_FLAG_WRITE;
1da177e4 LT	125	break;
	126	case 1: /* read, present */
	127	goto acc_err;
	128	case 0: /* read, not present */
df67b3da	129	if (!(vma->vm_flags & (VM_READ \| VM_EXEC \| VM_WRITE)))
1da177e4 LT	130	goto acc_err;
	131	}
	132
	133	/*
	134	* If for any reason at all we couldn't handle the fault,
	135	* make sure we exit gracefully rather than endlessly redo
	136	* the fault.
	137	*/
	138
dcddffd4	139	fault = handle_mm_fault(vma, address, flags);
8e398f63	140	pr_debug("handle_mm_fault returns %d\n", fault);
b637a6b1 KC	141
	142	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
	143	return 0;
	144
83c54070 NP	145	if (unlikely(fault & VM_FAULT_ERROR)) {
	146	if (fault & VM_FAULT_OOM)
	147	goto out_of_memory;
33692f27 LT	148	else if (fault & VM_FAULT_SIGSEGV)
33692f27 LT	149	goto map_err;
83c54070 NP	150	else if (fault & VM_FAULT_SIGBUS)
	151	goto bus_err;
	152	BUG();
1da177e4	153	}
b637a6b1 KC	154
	155	/*
	156	* Major/minor page fault accounting is only done on the
	157	* initial attempt. If we go through a retry, it is extremely
	158	* likely that the page will be found in page cache at that point.
	159	*/
	160	if (flags & FAULT_FLAG_ALLOW_RETRY) {
	161	if (fault & VM_FAULT_MAJOR)
	162	current->maj_flt++;
	163	else
	164	current->min_flt++;
	165	if (fault & VM_FAULT_RETRY) {
	166	/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
	167	* of starvation. */
	168	flags &= ~FAULT_FLAG_ALLOW_RETRY;
45cac65b	169	flags \|= FAULT_FLAG_TRIED;
b637a6b1 KC	170
	171	/*
	172	* No need to up_read(&mm->mmap_sem) as we would
	173	* have already released it in __lock_page_or_retry
	174	* in mm/filemap.c.
	175	*/
	176
	177	goto retry;
	178	}
	179	}
1da177e4 LT	180
	181	up_read(&mm->mmap_sem);
	182	return 0;
	183
	184	/*
	185	* We ran out of memory, or some other thing happened to us that made
	186	* us unable to handle the page fault gracefully.
	187	*/
	188	out_of_memory:
	189	up_read(&mm->mmap_sem);
adbf6e69 NP	190	if (!user_mode(regs))
	191	goto no_context;
	192	pagefault_out_of_memory();
	193	return 0;
1da177e4 LT	194
	195	no_context:
	196	current->thread.signo = SIGBUS;
	197	current->thread.faddr = address;
	198	return send_fault_sig(regs);
	199
	200	bus_err:
	201	current->thread.signo = SIGBUS;
	202	current->thread.code = BUS_ADRERR;
	203	current->thread.faddr = address;
	204	goto send_sig;
	205
	206	map_err:
	207	current->thread.signo = SIGSEGV;
	208	current->thread.code = SEGV_MAPERR;
	209	current->thread.faddr = address;
	210	goto send_sig;
	211
	212	acc_err:
	213	current->thread.signo = SIGSEGV;
	214	current->thread.code = SEGV_ACCERR;
	215	current->thread.faddr = address;
	216
	217	send_sig:
	218	up_read(&mm->mmap_sem);
	219	return send_fault_sig(regs);
	220	}