[net-next-2.6.git] / arch / powerpc / mm / subpage-prot.c

/*
 * Copyright 2007-2008 Paul Mackerras, IBM Corp.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>

#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/tlbflush.h>

/*
 * Free all pages allocated for subpage protection maps and pointers.
 * Also makes sure that the subpage_prot_table structure is
 * reinitialized for the next user.
 */
void subpage_prot_free(struct mm_struct *mm)
{
	struct subpage_prot_table *spt = &mm->context.spt;
	unsigned long i, j, addr;
	u32 **p;

	for (i = 0; i < 4; ++i) {
		if (spt->low_prot[i]) {
			free_page((unsigned long)spt->low_prot[i]);
			spt->low_prot[i] = NULL;
		}
	}
	addr = 0;
	for (i = 0; i < 2; ++i) {
		p = spt->protptrs[i];
		if (!p)
			continue;
		spt->protptrs[i] = NULL;
		for (j = 0; j < SBP_L2_COUNT && addr < spt->maxaddr;
		     ++j, addr += PAGE_SIZE)
			if (p[j])
				free_page((unsigned long)p[j]);
		free_page((unsigned long)p);
	}
	spt->maxaddr = 0;
}

void subpage_prot_init_new_context(struct mm_struct *mm)
{
	struct subpage_prot_table *spt = &mm->context.spt;

	memset(spt, 0, sizeof(*spt));
}

static void hpte_flush_range(struct mm_struct *mm, unsigned long addr,
			     int npages)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;
	spinlock_t *ptl;

	pgd = pgd_offset(mm, addr);
	if (pgd_none(*pgd))
		return;
	pud = pud_offset(pgd, addr);
	if (pud_none(*pud))
		return;
	pmd = pmd_offset(pud, addr);
	if (pmd_none(*pmd))
		return;
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
	arch_enter_lazy_mmu_mode();
	for (; npages > 0; --npages) {
		pte_update(mm, addr, pte, 0, 0);
		addr += PAGE_SIZE;
		++pte;
	}
	arch_leave_lazy_mmu_mode();
	pte_unmap_unlock(pte - 1, ptl);
}

/*
 * Clear the subpage protection map for an address range, allowing
 * all accesses that are allowed by the pte permissions.
 */
static void subpage_prot_clear(unsigned long addr, unsigned long len)
{
	struct mm_struct *mm = current->mm;
	struct subpage_prot_table *spt = &mm->context.spt;
	u32 **spm, *spp;
	int i, nw;
	unsigned long next, limit;

	down_write(&mm->mmap_sem);
	limit = addr + len;
	if (limit > spt->maxaddr)
		limit = spt->maxaddr;
	for (; addr < limit; addr = next) {
		next = pmd_addr_end(addr, limit);
		if (addr < 0x100000000) {
			spm = spt->low_prot;
		} else {
			spm = spt->protptrs[addr >> SBP_L3_SHIFT];
			if (!spm)
				continue;
		}
		spp = spm[(addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1)];
		if (!spp)
			continue;
		spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1);

		i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
		nw = PTRS_PER_PTE - i;
		if (addr + (nw << PAGE_SHIFT) > next)
			nw = (next - addr) >> PAGE_SHIFT;

		memset(spp, 0, nw * sizeof(u32));

		/* now flush any existing HPTEs for the range */
		hpte_flush_range(mm, addr, nw);
	}
	up_write(&mm->mmap_sem);
}

/*
 * Copy in a subpage protection map for an address range.
 * The map has 2 bits per 4k subpage, so 32 bits per 64k page.
 * Each 2-bit field is 0 to allow any access, 1 to prevent writes,
 * 2 or 3 to prevent all accesses.
 * Note that the normal page protections also apply; the subpage
 * protection mechanism is an additional constraint, so putting 0
 * in a 2-bit field won't allow writes to a page that is otherwise
 * write-protected.
 */
long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map)
{
	struct mm_struct *mm = current->mm;
	struct subpage_prot_table *spt = &mm->context.spt;
	u32 **spm, *spp;
	int i, nw;
	unsigned long next, limit;
	int err;

	/* Check parameters */
	if ((addr & ~PAGE_MASK) || (len & ~PAGE_MASK) ||
	    addr >= TASK_SIZE || len >= TASK_SIZE || addr + len > TASK_SIZE)
		return -EINVAL;

	if (is_hugepage_only_range(mm, addr, len))
		return -EINVAL;

	if (!map) {
		/* Clear out the protection map for the address range */
		subpage_prot_clear(addr, len);
		return 0;
	}

	if (!access_ok(VERIFY_READ, map, (len >> PAGE_SHIFT) * sizeof(u32)))
		return -EFAULT;

	down_write(&mm->mmap_sem);
	for (limit = addr + len; addr < limit; addr = next) {
		next = pmd_addr_end(addr, limit);
		err = -ENOMEM;
		if (addr < 0x100000000) {
			spm = spt->low_prot;
		} else {
			spm = spt->protptrs[addr >> SBP_L3_SHIFT];
			if (!spm) {
				spm = (u32 **)get_zeroed_page(GFP_KERNEL);
				if (!spm)
					goto out;
				spt->protptrs[addr >> SBP_L3_SHIFT] = spm;
			}
		}
		spm += (addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1);
		spp = *spm;
		if (!spp) {
			spp = (u32 *)get_zeroed_page(GFP_KERNEL);
			if (!spp)
				goto out;
			*spm = spp;
		}
		spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1);

		local_irq_disable();
		demote_segment_4k(mm, addr);
		local_irq_enable();

		i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
		nw = PTRS_PER_PTE - i;
		if (addr + (nw << PAGE_SHIFT) > next)
			nw = (next - addr) >> PAGE_SHIFT;

		up_write(&mm->mmap_sem);
		err = -EFAULT;
		if (__copy_from_user(spp, map, nw * sizeof(u32)))
			goto out2;
		map += nw;
		down_write(&mm->mmap_sem);

		/* now flush any existing HPTEs for the range */
		hpte_flush_range(mm, addr, nw);
	}
	if (limit > spt->maxaddr)
		spt->maxaddr = limit;
	err = 0;
 out:
	up_write(&mm->mmap_sem);
 out2:
	return err;
}
Commit	Line	Data
fa28237c PM	1	/*
	2	* Copyright 2007-2008 Paul Mackerras, IBM Corp.
	3	*
	4	* This program is free software; you can redistribute it and/or
	5	* modify it under the terms of the GNU General Public License
	6	* as published by the Free Software Foundation; either version
	7	* 2 of the License, or (at your option) any later version.
	8	*/
	9
	10	#include <linux/errno.h>
	11	#include <linux/kernel.h>
	12	#include <linux/gfp.h>
fa28237c PM	13	#include <linux/types.h>
	14	#include <linux/mm.h>
	15	#include <linux/hugetlb.h>
	16
	17	#include <asm/pgtable.h>
	18	#include <asm/uaccess.h>
	19	#include <asm/tlbflush.h>
	20
	21	/*
	22	* Free all pages allocated for subpage protection maps and pointers.
	23	* Also makes sure that the subpage_prot_table structure is
	24	* reinitialized for the next user.
	25	*/
d28513bc	26	void subpage_prot_free(struct mm_struct *mm)
fa28237c	27	{
d28513bc	28	struct subpage_prot_table *spt = &mm->context.spt;
fa28237c PM	29	unsigned long i, j, addr;
	30	u32 **p;
	31
	32	for (i = 0; i < 4; ++i) {
	33	if (spt->low_prot[i]) {
	34	free_page((unsigned long)spt->low_prot[i]);
	35	spt->low_prot[i] = NULL;
	36	}
	37	}
	38	addr = 0;
	39	for (i = 0; i < 2; ++i) {
	40	p = spt->protptrs[i];
	41	if (!p)
	42	continue;
	43	spt->protptrs[i] = NULL;
	44	for (j = 0; j < SBP_L2_COUNT && addr < spt->maxaddr;
	45	++j, addr += PAGE_SIZE)
	46	if (p[j])
	47	free_page((unsigned long)p[j]);
	48	free_page((unsigned long)p);
	49	}
	50	spt->maxaddr = 0;
	51	}
	52
d28513bc DG	53	void subpage_prot_init_new_context(struct mm_struct *mm)
	54	{
	55	struct subpage_prot_table *spt = &mm->context.spt;
	56
	57	memset(spt, 0, sizeof(*spt));
	58	}
	59
fa28237c PM	60	static void hpte_flush_range(struct mm_struct *mm, unsigned long addr,
	61	int npages)
	62	{
	63	pgd_t *pgd;
	64	pud_t *pud;
	65	pmd_t *pmd;
	66	pte_t *pte;
	67	spinlock_t *ptl;
	68
	69	pgd = pgd_offset(mm, addr);
	70	if (pgd_none(*pgd))
	71	return;
	72	pud = pud_offset(pgd, addr);
	73	if (pud_none(*pud))
	74	return;
	75	pmd = pmd_offset(pud, addr);
	76	if (pmd_none(*pmd))
	77	return;
	78	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
	79	arch_enter_lazy_mmu_mode();
	80	for (; npages > 0; --npages) {
	81	pte_update(mm, addr, pte, 0, 0);
	82	addr += PAGE_SIZE;
	83	++pte;
	84	}
	85	arch_leave_lazy_mmu_mode();
	86	pte_unmap_unlock(pte - 1, ptl);
	87	}
	88
	89	/*
	90	* Clear the subpage protection map for an address range, allowing
	91	* all accesses that are allowed by the pte permissions.
	92	*/
	93	static void subpage_prot_clear(unsigned long addr, unsigned long len)
	94	{
	95	struct mm_struct *mm = current->mm;
d28513bc	96	struct subpage_prot_table *spt = &mm->context.spt;
fa28237c PM	97	u32 *spm, spp;
	98	int i, nw;
	99	unsigned long next, limit;
	100
	101	down_write(&mm->mmap_sem);
	102	limit = addr + len;
	103	if (limit > spt->maxaddr)
	104	limit = spt->maxaddr;
	105	for (; addr < limit; addr = next) {
	106	next = pmd_addr_end(addr, limit);
	107	if (addr < 0x100000000) {
	108	spm = spt->low_prot;
	109	} else {
	110	spm = spt->protptrs[addr >> SBP_L3_SHIFT];
	111	if (!spm)
	112	continue;
	113	}
	114	spp = spm[(addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1)];
	115	if (!spp)
	116	continue;
	117	spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1);
	118
	119	i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
	120	nw = PTRS_PER_PTE - i;
	121	if (addr + (nw << PAGE_SHIFT) > next)
	122	nw = (next - addr) >> PAGE_SHIFT;
	123
	124	memset(spp, 0, nw * sizeof(u32));
	125
	126	/* now flush any existing HPTEs for the range */
	127	hpte_flush_range(mm, addr, nw);
	128	}
	129	up_write(&mm->mmap_sem);
	130	}
	131
	132	/*
	133	* Copy in a subpage protection map for an address range.
	134	* The map has 2 bits per 4k subpage, so 32 bits per 64k page.
	135	* Each 2-bit field is 0 to allow any access, 1 to prevent writes,
	136	* 2 or 3 to prevent all accesses.
	137	* Note that the normal page protections also apply; the subpage
	138	* protection mechanism is an additional constraint, so putting 0
	139	* in a 2-bit field won't allow writes to a page that is otherwise
	140	* write-protected.
	141	*/
	142	long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map)
	143	{
	144	struct mm_struct *mm = current->mm;
d28513bc	145	struct subpage_prot_table *spt = &mm->context.spt;
fa28237c PM	146	u32 *spm, spp;
	147	int i, nw;
	148	unsigned long next, limit;
	149	int err;
	150
	151	/* Check parameters */
	152	if ((addr & ~PAGE_MASK) \|\| (len & ~PAGE_MASK) \|\|
	153	addr >= TASK_SIZE \|\| len >= TASK_SIZE \|\| addr + len > TASK_SIZE)
	154	return -EINVAL;
	155
	156	if (is_hugepage_only_range(mm, addr, len))
	157	return -EINVAL;
	158
	159	if (!map) {
	160	/* Clear out the protection map for the address range */
	161	subpage_prot_clear(addr, len);
	162	return 0;
	163	}
	164
	165	if (!access_ok(VERIFY_READ, map, (len >> PAGE_SHIFT) * sizeof(u32)))
	166	return -EFAULT;
	167
	168	down_write(&mm->mmap_sem);
	169	for (limit = addr + len; addr < limit; addr = next) {
	170	next = pmd_addr_end(addr, limit);
	171	err = -ENOMEM;
	172	if (addr < 0x100000000) {
	173	spm = spt->low_prot;
	174	} else {
	175	spm = spt->protptrs[addr >> SBP_L3_SHIFT];
	176	if (!spm) {
	177	spm = (u32 **)get_zeroed_page(GFP_KERNEL);
	178	if (!spm)
	179	goto out;
	180	spt->protptrs[addr >> SBP_L3_SHIFT] = spm;
	181	}
	182	}
	183	spm += (addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1);
	184	spp = *spm;
	185	if (!spp) {
	186	spp = (u32 *)get_zeroed_page(GFP_KERNEL);
	187	if (!spp)
	188	goto out;
	189	*spm = spp;
	190	}
	191	spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1);
	192
	193	local_irq_disable();
	194	demote_segment_4k(mm, addr);
	195	local_irq_enable();
	196
	197	i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
	198	nw = PTRS_PER_PTE - i;
	199	if (addr + (nw << PAGE_SHIFT) > next)
	200	nw = (next - addr) >> PAGE_SHIFT;
	201
	202	up_write(&mm->mmap_sem);
	203	err = -EFAULT;
	204	if (__copy_from_user(spp, map, nw * sizeof(u32)))
	205	goto out2;
	206	map += nw;
	207	down_write(&mm->mmap_sem);
	208
	209	/* now flush any existing HPTEs for the range */
210	hpte_flush_range(mm, addr, nw);
211	}
212	if (limit > spt->maxaddr)
213	spt->maxaddr = limit;
214	err = 0;
215	out:
216	up_write(&mm->mmap_sem);
217	out2:
218	return err;
219	}