[mirror_ubuntu-eoan-kernel.git] / arch / parisc / 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, 1996, 1997, 1998 by Ralf Baechle
 * Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
 * Copyright 1999 Hewlett Packard Co.
 *
 */

#include <linux/mm.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/module.h>

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

#define PRINT_USER_FAULTS /* (turn this on if you want user faults to be */
			 /*  dumped to the console via printk)          */


/* Various important other fields */
#define bit22set(x)		(x & 0x00000200)
#define bits23_25set(x)		(x & 0x000001c0)
#define isGraphicsFlushRead(x)	((x & 0xfc003fdf) == 0x04001a80)
				/* extended opcode is 0x6a */

#define BITSSET		0x1c0	/* for identifying LDCW */


DEFINE_PER_CPU(struct exception_data, exception_data);

/*
 * parisc_acctyp(unsigned int inst) --
 *    Given a PA-RISC memory access instruction, determine if the
 *    the instruction would perform a memory read or memory write
 *    operation.
 *
 *    This function assumes that the given instruction is a memory access
 *    instruction (i.e. you should really only call it if you know that
 *    the instruction has generated some sort of a memory access fault).
 *
 * Returns:
 *   VM_READ  if read operation
 *   VM_WRITE if write operation
 *   VM_EXEC  if execute operation
 */
static unsigned long
parisc_acctyp(unsigned long code, unsigned int inst)
{
	if (code == 6 || code == 16)
	    return VM_EXEC;

	switch (inst & 0xf0000000) {
	case 0x40000000: /* load */
	case 0x50000000: /* new load */
		return VM_READ;

	case 0x60000000: /* store */
	case 0x70000000: /* new store */
		return VM_WRITE;

	case 0x20000000: /* coproc */
	case 0x30000000: /* coproc2 */
		if (bit22set(inst))
			return VM_WRITE;

	case 0x0: /* indexed/memory management */
		if (bit22set(inst)) {
			/*
			 * Check for the 'Graphics Flush Read' instruction.
			 * It resembles an FDC instruction, except for bits
			 * 20 and 21. Any combination other than zero will
			 * utilize the block mover functionality on some
			 * older PA-RISC platforms.  The case where a block
			 * move is performed from VM to graphics IO space
			 * should be treated as a READ.
			 *
			 * The significance of bits 20,21 in the FDC
			 * instruction is:
			 *
			 *   00  Flush data cache (normal instruction behavior)
			 *   01  Graphics flush write  (IO space -> VM)
			 *   10  Graphics flush read   (VM -> IO space)
			 *   11  Graphics flush read/write (VM <-> IO space)
			 */
			if (isGraphicsFlushRead(inst))
				return VM_READ;
			return VM_WRITE;
		} else {
			/*
			 * Check for LDCWX and LDCWS (semaphore instructions).
			 * If bits 23 through 25 are all 1's it is one of
			 * the above two instructions and is a write.
			 *
			 * Note: With the limited bits we are looking at,
			 * this will also catch PROBEW and PROBEWI. However,
			 * these should never get in here because they don't
			 * generate exceptions of the type:
			 *   Data TLB miss fault/data page fault
			 *   Data memory protection trap
			 */
			if (bits23_25set(inst) == BITSSET)
				return VM_WRITE;
		}
		return VM_READ; /* Default */
	}
	return VM_READ; /* Default */
}

#undef bit22set
#undef bits23_25set
#undef isGraphicsFlushRead
#undef BITSSET


#if 0
/* This is the treewalk to find a vma which is the highest that has
 * a start < addr.  We're using find_vma_prev instead right now, but
 * we might want to use this at some point in the future.  Probably
 * not, but I want it committed to CVS so I don't lose it :-)
 */
			while (tree != vm_avl_empty) {
				if (tree->vm_start > addr) {
					tree = tree->vm_avl_left;
				} else {
					prev = tree;
					if (prev->vm_next == NULL)
						break;
					if (prev->vm_next->vm_start > addr)
						break;
					tree = tree->vm_avl_right;
				}
			}
#endif

int fixup_exception(struct pt_regs *regs)
{
	const struct exception_table_entry *fix;

	/* If we only stored 32bit addresses in the exception table we can drop
	 * out if we faulted on a 64bit address. */
	if ((sizeof(regs->iaoq[0]) > sizeof(fix->insn))
		&& (regs->iaoq[0] >> 32))
			return 0;

	fix = search_exception_tables(regs->iaoq[0]);
	if (fix) {
		struct exception_data *d;
		d = &__get_cpu_var(exception_data);
		d->fault_ip = regs->iaoq[0];
		d->fault_space = regs->isr;
		d->fault_addr = regs->ior;

		regs->iaoq[0] = ((fix->fixup) & ~3);
		/*
		 * NOTE: In some cases the faulting instruction
		 * may be in the delay slot of a branch. We
		 * don't want to take the branch, so we don't
		 * increment iaoq[1], instead we set it to be
		 * iaoq[0]+4, and clear the B bit in the PSW
		 */
		regs->iaoq[1] = regs->iaoq[0] + 4;
		regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */

		return 1;
	}

	return 0;
}

void do_page_fault(struct pt_regs *regs, unsigned long code,
			      unsigned long address)
{
	struct vm_area_struct *vma, *prev_vma;
	struct task_struct *tsk;
	struct mm_struct *mm;
	unsigned long acc_type;
	int fault;
	unsigned int flags;

	if (in_atomic())
		goto no_context;

	tsk = current;
	mm = tsk->mm;
	if (!mm)
		goto no_context;

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

	acc_type = parisc_acctyp(code, regs->iir);
	if (acc_type & VM_WRITE)
		flags |= FAULT_FLAG_WRITE;
retry:
	down_read(&mm->mmap_sem);
	vma = find_vma_prev(mm, address, &prev_vma);
	if (!vma || address < vma->vm_start)
		goto check_expansion;
/*
 * Ok, we have a good vm_area for this memory access. We still need to
 * check the access permissions.
 */

good_area:

	if ((vma->vm_flags & acc_type) != acc_type)
		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;

	if (unlikely(fault & VM_FAULT_ERROR)) {
		/*
		 * We hit a shared mapping outside of the file, or some
		 * other thing happened to us that made us unable to
		 * handle the page fault gracefully.
		 */
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGBUS)
			goto bad_area;
		BUG();
	}
	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_ALLOW_RETRY;

			/*
			 * 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;

check_expansion:
	vma = prev_vma;
	if (vma && (expand_stack(vma, address) == 0))
		goto good_area;

/*
 * Something tried to access memory that isn't in our memory map..
 */
bad_area:
	up_read(&mm->mmap_sem);

	if (user_mode(regs)) {
		struct siginfo si;

#ifdef PRINT_USER_FAULTS
		printk(KERN_DEBUG "\n");
		printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n",
		    task_pid_nr(tsk), tsk->comm, code, address);
		if (vma) {
			printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n",
					vma->vm_start, vma->vm_end);
		}
		show_regs(regs);
#endif
		/* FIXME: actually we need to get the signo and code correct */
		si.si_signo = SIGSEGV;
		si.si_errno = 0;
		si.si_code = SEGV_MAPERR;
		si.si_addr = (void __user *) address;
		force_sig_info(SIGSEGV, &si, current);
		return;
	}

no_context:

	if (!user_mode(regs) && fixup_exception(regs)) {
		return;
	}

	parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);

  out_of_memory:
	up_read(&mm->mmap_sem);
	if (!user_mode(regs))
		goto no_context;
	pagefault_out_of_memory();
}
Commit	Line	Data
071327ec	1	/*
1da177e4 LT	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	*
	7	* Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle
	8	* Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
	9	* Copyright 1999 Hewlett Packard Co.
	10	*
	11	*/
	12
	13	#include <linux/mm.h>
	14	#include <linux/ptrace.h>
	15	#include <linux/sched.h>
	16	#include <linux/interrupt.h>
	17	#include <linux/module.h>
	18
	19	#include <asm/uaccess.h>
	20	#include <asm/traps.h>
	21
	22	#define PRINT_USER_FAULTS /* (turn this on if you want user faults to be */
	23	/* dumped to the console via printk) */
	24
	25
1da177e4 LT	26	/* Various important other fields */
	27	#define bit22set(x) (x & 0x00000200)
	28	#define bits23_25set(x) (x & 0x000001c0)
	29	#define isGraphicsFlushRead(x) ((x & 0xfc003fdf) == 0x04001a80)
	30	/* extended opcode is 0x6a */
	31
	32	#define BITSSET 0x1c0 /* for identifying LDCW */
	33
	34
	35	DEFINE_PER_CPU(struct exception_data, exception_data);
	36
	37	/*
	38	* parisc_acctyp(unsigned int inst) --
	39	* Given a PA-RISC memory access instruction, determine if the
	40	* the instruction would perform a memory read or memory write
	41	* operation.
	42	*
	43	* This function assumes that the given instruction is a memory access
	44	* instruction (i.e. you should really only call it if you know that
	45	* the instruction has generated some sort of a memory access fault).
	46	*
	47	* Returns:
	48	* VM_READ if read operation
	49	* VM_WRITE if write operation
	50	* VM_EXEC if execute operation
	51	*/
	52	static unsigned long
	53	parisc_acctyp(unsigned long code, unsigned int inst)
	54	{
	55	if (code == 6 \|\| code == 16)
	56	return VM_EXEC;
	57
	58	switch (inst & 0xf0000000) {
	59	case 0x40000000: /* load */
	60	case 0x50000000: /* new load */
	61	return VM_READ;
	62
	63	case 0x60000000: /* store */
	64	case 0x70000000: /* new store */
	65	return VM_WRITE;
	66
	67	case 0x20000000: /* coproc */
	68	case 0x30000000: /* coproc2 */
	69	if (bit22set(inst))
	70	return VM_WRITE;
	71
	72	case 0x0: /* indexed/memory management */
	73	if (bit22set(inst)) {
	74	/*
	75	* Check for the 'Graphics Flush Read' instruction.
	76	* It resembles an FDC instruction, except for bits
	77	* 20 and 21. Any combination other than zero will
	78	* utilize the block mover functionality on some
	79	* older PA-RISC platforms. The case where a block
	80	* move is performed from VM to graphics IO space
	81	* should be treated as a READ.
	82	*
	83	* The significance of bits 20,21 in the FDC
	84	* instruction is:
	85	*
	86	* 00 Flush data cache (normal instruction behavior)
	87	* 01 Graphics flush write (IO space -> VM)
	88	* 10 Graphics flush read (VM -> IO space)
	89	* 11 Graphics flush read/write (VM <-> IO space)
90	*/
91	if (isGraphicsFlushRead(inst))
92	return VM_READ;
93	return VM_WRITE;
94	} else {
95	/*
96	* Check for LDCWX and LDCWS (semaphore instructions).
97	* If bits 23 through 25 are all 1's it is one of
98	* the above two instructions and is a write.
99	*
100	* Note: With the limited bits we are looking at,
101	* this will also catch PROBEW and PROBEWI. However,
102	* these should never get in here because they don't
103	* generate exceptions of the type:
104	* Data TLB miss fault/data page fault
105	* Data memory protection trap
106	*/
107	if (bits23_25set(inst) == BITSSET)
108	return VM_WRITE;
109	}
110	return VM_READ; /* Default */
111	}
112	return VM_READ; /* Default */
113	}
114
115	#undef bit22set
116	#undef bits23_25set
117	#undef isGraphicsFlushRead
118	#undef BITSSET
119
120
121	#if 0
122	/* This is the treewalk to find a vma which is the highest that has
123	* a start < addr. We're using find_vma_prev instead right now, but
124	* we might want to use this at some point in the future. Probably
125	* not, but I want it committed to CVS so I don't lose it :-)
126	*/
127	while (tree != vm_avl_empty) {
128	if (tree->vm_start > addr) {
129	tree = tree->vm_avl_left;
130	} else {
131	prev = tree;
132	if (prev->vm_next == NULL)
133	break;
134	if (prev->vm_next->vm_start > addr)
135	break;
136	tree = tree->vm_avl_right;
137	}
138	}
139	#endif
140
c61c25eb KM	141	int fixup_exception(struct pt_regs *regs)
	142	{
	143	const struct exception_table_entry *fix;
	144
61dbbaeb HD	145	/* If we only stored 32bit addresses in the exception table we can drop
	146	* out if we faulted on a 64bit address. */
	147	if ((sizeof(regs->iaoq[0]) > sizeof(fix->insn))
	148	&& (regs->iaoq[0] >> 32))
	149	return 0;
	150
c61c25eb KM	151	fix = search_exception_tables(regs->iaoq[0]);
	152	if (fix) {
	153	struct exception_data *d;
	154	d = &__get_cpu_var(exception_data);
	155	d->fault_ip = regs->iaoq[0];
	156	d->fault_space = regs->isr;
	157	d->fault_addr = regs->ior;
	158
	159	regs->iaoq[0] = ((fix->fixup) & ~3);
	160	/*
	161	* NOTE: In some cases the faulting instruction
	162	* may be in the delay slot of a branch. We
	163	* don't want to take the branch, so we don't
	164	* increment iaoq[1], instead we set it to be
	165	* iaoq[0]+4, and clear the B bit in the PSW
	166	*/
	167	regs->iaoq[1] = regs->iaoq[0] + 4;
	168	regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
	169
	170	return 1;
	171	}
	172
	173	return 0;
	174	}
	175
1da177e4 LT	176	void do_page_fault(struct pt_regs *regs, unsigned long code,
	177	unsigned long address)
	178	{
	179	struct vm_area_struct vma, prev_vma;
2d8b22de JDA	180	struct task_struct *tsk;
2d8b22de JDA	181	struct mm_struct *mm;
1da177e4	182	unsigned long acc_type;
83c54070	183	int fault;
2d8b22de	184	unsigned int flags;
1da177e4	185
2d8b22de	186	if (in_atomic())
1da177e4 LT	187	goto no_context;
1da177e4 LT	188
2d8b22de JDA	189	tsk = current;
	190	mm = tsk->mm;
	191	if (!mm)
	192	goto no_context;
	193
	194	flags = FAULT_FLAG_ALLOW_RETRY \| FAULT_FLAG_KILLABLE;
759496ba JW	195	if (user_mode(regs))
759496ba JW	196	flags \|= FAULT_FLAG_USER;
0772dac1 FP	197
0772dac1 FP	198	acc_type = parisc_acctyp(code, regs->iir);
759496ba JW	199	if (acc_type & VM_WRITE)
759496ba JW	200	flags \|= FAULT_FLAG_WRITE;
38057477	201	retry:
1da177e4 LT	202	down_read(&mm->mmap_sem);
	203	vma = find_vma_prev(mm, address, &prev_vma);
	204	if (!vma \|\| address < vma->vm_start)
	205	goto check_expansion;
	206	/*
	207	* Ok, we have a good vm_area for this memory access. We still need to
	208	* check the access permissions.
	209	*/
	210
	211	good_area:
	212
1da177e4 LT	213	if ((vma->vm_flags & acc_type) != acc_type)
	214	goto bad_area;
	215
	216	/*
	217	* If for any reason at all we couldn't handle the fault, make
	218	* sure we exit gracefully rather than endlessly redo the
	219	* fault.
	220	*/
	221
759496ba	222	fault = handle_mm_fault(mm, vma, address, flags);
38057477 KC	223
	224	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
	225	return;
	226
83c54070	227	if (unlikely(fault & VM_FAULT_ERROR)) {
1da177e4	228	/*
67a5a59d	229	* We hit a shared mapping outside of the file, or some
6e346228 LT	230	* other thing happened to us that made us unable to
6e346228 LT	231	* handle the page fault gracefully.
1da177e4	232	*/
83c54070 NP	233	if (fault & VM_FAULT_OOM)
	234	goto out_of_memory;
	235	else if (fault & VM_FAULT_SIGBUS)
	236	goto bad_area;
	237	BUG();
1da177e4	238	}
38057477 KC	239	if (flags & FAULT_FLAG_ALLOW_RETRY) {
	240	if (fault & VM_FAULT_MAJOR)
	241	current->maj_flt++;
	242	else
	243	current->min_flt++;
	244	if (fault & VM_FAULT_RETRY) {
	245	flags &= ~FAULT_FLAG_ALLOW_RETRY;
	246
	247	/*
	248	* No need to up_read(&mm->mmap_sem) as we would
	249	* have already released it in __lock_page_or_retry
	250	* in mm/filemap.c.
	251	*/
	252
	253	goto retry;
	254	}
	255	}
1da177e4 LT	256	up_read(&mm->mmap_sem);
	257	return;
	258
	259	check_expansion:
	260	vma = prev_vma;
	261	if (vma && (expand_stack(vma, address) == 0))
	262	goto good_area;
	263
	264	/*
	265	* Something tried to access memory that isn't in our memory map..
	266	*/
	267	bad_area:
	268	up_read(&mm->mmap_sem);
	269
	270	if (user_mode(regs)) {
	271	struct siginfo si;
	272
	273	#ifdef PRINT_USER_FAULTS
	274	printk(KERN_DEBUG "\n");
	275	printk(KERN_DEBUG "do_page_fault() pid=%d command='%s' type=%lu address=0x%08lx\n",
19c5870c	276	task_pid_nr(tsk), tsk->comm, code, address);
1da177e4 LT	277	if (vma) {
	278	printk(KERN_DEBUG "vm_start = 0x%08lx, vm_end = 0x%08lx\n",
	279	vma->vm_start, vma->vm_end);
	280	}
	281	show_regs(regs);
	282	#endif
	283	/* FIXME: actually we need to get the signo and code correct */
	284	si.si_signo = SIGSEGV;
	285	si.si_errno = 0;
	286	si.si_code = SEGV_MAPERR;
	287	si.si_addr = (void __user *) address;
	288	force_sig_info(SIGSEGV, &si, current);
	289	return;
	290	}
	291
	292	no_context:
	293
c61c25eb KM	294	if (!user_mode(regs) && fixup_exception(regs)) {
c61c25eb KM	295	return;
1da177e4 LT	296	}
	297
	298	parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
	299
	300	out_of_memory:
	301	up_read(&mm->mmap_sem);
53e30d02 NP	302	if (!user_mode(regs))
	303	goto no_context;
	304	pagefault_out_of_memory();
1da177e4	305	}