[thirdparty/kernel/linux.git] / arch / s390 / mm / pgalloc.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  Page table allocation functions
 *
 *    Copyright IBM Corp. 2016
 *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
 */

#include <linux/mm.h>
#include <linux/sysctl.h>
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
#include <asm/gmap.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>

#ifdef CONFIG_PGSTE

static int page_table_allocate_pgste_min = 0;
static int page_table_allocate_pgste_max = 1;
int page_table_allocate_pgste = 0;
EXPORT_SYMBOL(page_table_allocate_pgste);

static struct ctl_table page_table_sysctl[] = {
	{
		.procname	= "allocate_pgste",
		.data		= &page_table_allocate_pgste,
		.maxlen		= sizeof(int),
		.mode		= S_IRUGO | S_IWUSR,
		.proc_handler	= proc_dointvec,
		.extra1		= &page_table_allocate_pgste_min,
		.extra2		= &page_table_allocate_pgste_max,
	},
	{ }
};

static struct ctl_table page_table_sysctl_dir[] = {
	{
		.procname	= "vm",
		.maxlen		= 0,
		.mode		= 0555,
		.child		= page_table_sysctl,
	},
	{ }
};

static int __init page_table_register_sysctl(void)
{
	return register_sysctl_table(page_table_sysctl_dir) ? 0 : -ENOMEM;
}
__initcall(page_table_register_sysctl);

#endif /* CONFIG_PGSTE */

unsigned long *crst_table_alloc(struct mm_struct *mm)
{
	struct page *page = alloc_pages(GFP_KERNEL, 2);

	if (!page)
		return NULL;
	arch_set_page_dat(page, 2);
	return (unsigned long *) page_to_phys(page);
}

void crst_table_free(struct mm_struct *mm, unsigned long *table)
{
	free_pages((unsigned long) table, 2);
}

static void __crst_table_upgrade(void *arg)
{
	struct mm_struct *mm = arg;

	if (current->active_mm == mm) {
		clear_user_asce();
		set_user_asce(mm);
	}
	__tlb_flush_local();
}

int crst_table_upgrade(struct mm_struct *mm, unsigned long end)
{
	unsigned long *table, *pgd;
	int rc, notify;

	/* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */
	VM_BUG_ON(mm->context.asce_limit < _REGION2_SIZE);
	if (end >= TASK_SIZE_MAX)
		return -ENOMEM;
	rc = 0;
	notify = 0;
	while (mm->context.asce_limit < end) {
		table = crst_table_alloc(mm);
		if (!table) {
			rc = -ENOMEM;
			break;
		}
		spin_lock_bh(&mm->page_table_lock);
		pgd = (unsigned long *) mm->pgd;
		if (mm->context.asce_limit == _REGION2_SIZE) {
			crst_table_init(table, _REGION2_ENTRY_EMPTY);
			p4d_populate(mm, (p4d_t *) table, (pud_t *) pgd);
			mm->pgd = (pgd_t *) table;
			mm->context.asce_limit = _REGION1_SIZE;
			mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
				_ASCE_USER_BITS | _ASCE_TYPE_REGION2;
		} else {
			crst_table_init(table, _REGION1_ENTRY_EMPTY);
			pgd_populate(mm, (pgd_t *) table, (p4d_t *) pgd);
			mm->pgd = (pgd_t *) table;
			mm->context.asce_limit = -PAGE_SIZE;
			mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
				_ASCE_USER_BITS | _ASCE_TYPE_REGION1;
		}
		notify = 1;
		spin_unlock_bh(&mm->page_table_lock);
	}
	if (notify)
		on_each_cpu(__crst_table_upgrade, mm, 0);
	return rc;
}

void crst_table_downgrade(struct mm_struct *mm)
{
	pgd_t *pgd;

	/* downgrade should only happen from 3 to 2 levels (compat only) */
	VM_BUG_ON(mm->context.asce_limit != _REGION2_SIZE);

	if (current->active_mm == mm) {
		clear_user_asce();
		__tlb_flush_mm(mm);
	}

	pgd = mm->pgd;
	mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN);
	mm->context.asce_limit = _REGION3_SIZE;
	mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
			   _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT;
	crst_table_free(mm, (unsigned long *) pgd);

	if (current->active_mm == mm)
		set_user_asce(mm);
}

static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits)
{
	unsigned int old, new;

	do {
		old = atomic_read(v);
		new = old ^ bits;
	} while (atomic_cmpxchg(v, old, new) != old);
	return new;
}

#ifdef CONFIG_PGSTE

struct page *page_table_alloc_pgste(struct mm_struct *mm)
{
	struct page *page;
	unsigned long *table;

	page = alloc_page(GFP_KERNEL);
	if (page) {
		table = (unsigned long *) page_to_phys(page);
		clear_table(table, _PAGE_INVALID, PAGE_SIZE/2);
		clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2);
	}
	return page;
}

void page_table_free_pgste(struct page *page)
{
	__free_page(page);
}

#endif /* CONFIG_PGSTE */

/*
 * page table entry allocation/free routines.
 */
unsigned long *page_table_alloc(struct mm_struct *mm)
{
	unsigned long *table;
	struct page *page;
	unsigned int mask, bit;

	/* Try to get a fragment of a 4K page as a 2K page table */
	if (!mm_alloc_pgste(mm)) {
		table = NULL;
		spin_lock_bh(&mm->context.lock);
		if (!list_empty(&mm->context.pgtable_list)) {
			page = list_first_entry(&mm->context.pgtable_list,
						struct page, lru);
			mask = atomic_read(&page->_mapcount);
			mask = (mask | (mask >> 4)) & 3;
			if (mask != 3) {
				table = (unsigned long *) page_to_phys(page);
				bit = mask & 1;		/* =1 -> second 2K */
				if (bit)
					table += PTRS_PER_PTE;
				atomic_xor_bits(&page->_mapcount, 1U << bit);
				list_del(&page->lru);
			}
		}
		spin_unlock_bh(&mm->context.lock);
		if (table)
			return table;
	}
	/* Allocate a fresh page */
	page = alloc_page(GFP_KERNEL);
	if (!page)
		return NULL;
	if (!pgtable_page_ctor(page)) {
		__free_page(page);
		return NULL;
	}
	arch_set_page_dat(page, 0);
	/* Initialize page table */
	table = (unsigned long *) page_to_phys(page);
	if (mm_alloc_pgste(mm)) {
		/* Return 4K page table with PGSTEs */
		atomic_set(&page->_mapcount, 3);
		clear_table(table, _PAGE_INVALID, PAGE_SIZE/2);
		clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2);
	} else {
		/* Return the first 2K fragment of the page */
		atomic_set(&page->_mapcount, 1);
		clear_table(table, _PAGE_INVALID, PAGE_SIZE);
		spin_lock_bh(&mm->context.lock);
		list_add(&page->lru, &mm->context.pgtable_list);
		spin_unlock_bh(&mm->context.lock);
	}
	return table;
}

void page_table_free(struct mm_struct *mm, unsigned long *table)
{
	struct page *page;
	unsigned int bit, mask;

	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
	if (!mm_alloc_pgste(mm)) {
		/* Free 2K page table fragment of a 4K page */
		bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t));
		spin_lock_bh(&mm->context.lock);
		mask = atomic_xor_bits(&page->_mapcount, 1U << bit);
		if (mask & 3)
			list_add(&page->lru, &mm->context.pgtable_list);
		else
			list_del(&page->lru);
		spin_unlock_bh(&mm->context.lock);
		if (mask != 0)
			return;
	}

	pgtable_page_dtor(page);
	atomic_set(&page->_mapcount, -1);
	__free_page(page);
}

void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table,
			 unsigned long vmaddr)
{
	struct mm_struct *mm;
	struct page *page;
	unsigned int bit, mask;

	mm = tlb->mm;
	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
	if (mm_alloc_pgste(mm)) {
		gmap_unlink(mm, table, vmaddr);
		table = (unsigned long *) (__pa(table) | 3);
		tlb_remove_table(tlb, table);
		return;
	}
	bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t));
	spin_lock_bh(&mm->context.lock);
	mask = atomic_xor_bits(&page->_mapcount, 0x11U << bit);
	if (mask & 3)
		list_add_tail(&page->lru, &mm->context.pgtable_list);
	else
		list_del(&page->lru);
	spin_unlock_bh(&mm->context.lock);
	table = (unsigned long *) (__pa(table) | (1U << bit));
	tlb_remove_table(tlb, table);
}

static void __tlb_remove_table(void *_table)
{
	unsigned int mask = (unsigned long) _table & 3;
	void *table = (void *)((unsigned long) _table ^ mask);
	struct page *page = pfn_to_page(__pa(table) >> PAGE_SHIFT);

	switch (mask) {
	case 0:		/* pmd, pud, or p4d */
		free_pages((unsigned long) table, 2);
		break;
	case 1:		/* lower 2K of a 4K page table */
	case 2:		/* higher 2K of a 4K page table */
		if (atomic_xor_bits(&page->_mapcount, mask << 4) != 0)
			break;
		/* fallthrough */
	case 3:		/* 4K page table with pgstes */
		pgtable_page_dtor(page);
		atomic_set(&page->_mapcount, -1);
		__free_page(page);
		break;
	}
}

static void tlb_remove_table_smp_sync(void *arg)
{
	/* Simply deliver the interrupt */
}

static void tlb_remove_table_one(void *table)
{
	/*
	 * This isn't an RCU grace period and hence the page-tables cannot be
	 * assumed to be actually RCU-freed.
	 *
	 * It is however sufficient for software page-table walkers that rely
	 * on IRQ disabling. See the comment near struct mmu_table_batch.
	 */
	smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
	__tlb_remove_table(table);
}

static void tlb_remove_table_rcu(struct rcu_head *head)
{
	struct mmu_table_batch *batch;
	int i;

	batch = container_of(head, struct mmu_table_batch, rcu);

	for (i = 0; i < batch->nr; i++)
		__tlb_remove_table(batch->tables[i]);

	free_page((unsigned long)batch);
}

void tlb_table_flush(struct mmu_gather *tlb)
{
	struct mmu_table_batch **batch = &tlb->batch;

	if (*batch) {
		call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
		*batch = NULL;
	}
}

void tlb_remove_table(struct mmu_gather *tlb, void *table)
{
	struct mmu_table_batch **batch = &tlb->batch;

	tlb->mm->context.flush_mm = 1;
	if (*batch == NULL) {
		*batch = (struct mmu_table_batch *)
			__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
		if (*batch == NULL) {
			__tlb_flush_mm_lazy(tlb->mm);
			tlb_remove_table_one(table);
			return;
		}
		(*batch)->nr = 0;
	}
	(*batch)->tables[(*batch)->nr++] = table;
	if ((*batch)->nr == MAX_TABLE_BATCH)
		tlb_flush_mmu(tlb);
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1e133ab2 MS	2	/*
	3	* Page table allocation functions
	4	*
	5	* Copyright IBM Corp. 2016
	6	* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
	7	*/
	8
	9	#include <linux/mm.h>
	10	#include <linux/sysctl.h>
	11	#include <asm/mmu_context.h>
	12	#include <asm/pgalloc.h>
	13	#include <asm/gmap.h>
	14	#include <asm/tlb.h>
	15	#include <asm/tlbflush.h>
	16
	17	#ifdef CONFIG_PGSTE
	18
	19	static int page_table_allocate_pgste_min = 0;
	20	static int page_table_allocate_pgste_max = 1;
	21	int page_table_allocate_pgste = 0;
	22	EXPORT_SYMBOL(page_table_allocate_pgste);
	23
	24	static struct ctl_table page_table_sysctl[] = {
	25	{
	26	.procname = "allocate_pgste",
	27	.data = &page_table_allocate_pgste,
	28	.maxlen = sizeof(int),
	29	.mode = S_IRUGO \| S_IWUSR,
	30	.proc_handler = proc_dointvec,
	31	.extra1 = &page_table_allocate_pgste_min,
	32	.extra2 = &page_table_allocate_pgste_max,
	33	},
	34	{ }
	35	};
	36
	37	static struct ctl_table page_table_sysctl_dir[] = {
	38	{
	39	.procname = "vm",
	40	.maxlen = 0,
	41	.mode = 0555,
	42	.child = page_table_sysctl,
	43	},
	44	{ }
	45	};
	46
	47	static int __init page_table_register_sysctl(void)
	48	{
	49	return register_sysctl_table(page_table_sysctl_dir) ? 0 : -ENOMEM;
	50	}
	51	__initcall(page_table_register_sysctl);
	52
	53	#endif /* CONFIG_PGSTE */
	54
	55	unsigned long crst_table_alloc(struct mm_struct mm)
	56	{
	57	struct page *page = alloc_pages(GFP_KERNEL, 2);
	58
	59	if (!page)
	60	return NULL;
c9b5ad54	61	arch_set_page_dat(page, 2);
1e133ab2 MS	62	return (unsigned long *) page_to_phys(page);
	63	}
	64
	65	void crst_table_free(struct mm_struct mm, unsigned long table)
	66	{
	67	free_pages((unsigned long) table, 2);
	68	}
	69
	70	static void __crst_table_upgrade(void *arg)
	71	{
	72	struct mm_struct *mm = arg;
	73
	74	if (current->active_mm == mm) {
	75	clear_user_asce();
	76	set_user_asce(mm);
	77	}
	78	__tlb_flush_local();
	79	}
	80
1aea9b3f	81	int crst_table_upgrade(struct mm_struct *mm, unsigned long end)
1e133ab2 MS	82	{
1e133ab2 MS	83	unsigned long table, pgd;
1aea9b3f	84	int rc, notify;
1e133ab2	85
1aea9b3f	86	/* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */
2fc4876e	87	VM_BUG_ON(mm->context.asce_limit < _REGION2_SIZE);
1aea9b3f	88	if (end >= TASK_SIZE_MAX)
1e133ab2	89	return -ENOMEM;
1aea9b3f MS	90	rc = 0;
	91	notify = 0;
	92	while (mm->context.asce_limit < end) {
	93	table = crst_table_alloc(mm);
	94	if (!table) {
	95	rc = -ENOMEM;
	96	break;
	97	}
	98	spin_lock_bh(&mm->page_table_lock);
	99	pgd = (unsigned long *) mm->pgd;
f1c1174f	100	if (mm->context.asce_limit == _REGION2_SIZE) {
1aea9b3f MS	101	crst_table_init(table, _REGION2_ENTRY_EMPTY);
	102	p4d_populate(mm, (p4d_t ) table, (pud_t ) pgd);
	103	mm->pgd = (pgd_t *) table;
f1c1174f	104	mm->context.asce_limit = _REGION1_SIZE;
1aea9b3f MS	105	mm->context.asce = __pa(mm->pgd) \| _ASCE_TABLE_LENGTH \|
	106	_ASCE_USER_BITS \| _ASCE_TYPE_REGION2;
	107	} else {
	108	crst_table_init(table, _REGION1_ENTRY_EMPTY);
	109	pgd_populate(mm, (pgd_t ) table, (p4d_t ) pgd);
	110	mm->pgd = (pgd_t *) table;
	111	mm->context.asce_limit = -PAGE_SIZE;
	112	mm->context.asce = __pa(mm->pgd) \| _ASCE_TABLE_LENGTH \|
	113	_ASCE_USER_BITS \| _ASCE_TYPE_REGION1;
	114	}
	115	notify = 1;
	116	spin_unlock_bh(&mm->page_table_lock);
	117	}
	118	if (notify)
	119	on_each_cpu(__crst_table_upgrade, mm, 0);
	120	return rc;
1e133ab2 MS	121	}
1e133ab2 MS	122
723cacbd	123	void crst_table_downgrade(struct mm_struct *mm)
1e133ab2 MS	124	{
	125	pgd_t *pgd;
	126
723cacbd	127	/* downgrade should only happen from 3 to 2 levels (compat only) */
2fc4876e	128	VM_BUG_ON(mm->context.asce_limit != _REGION2_SIZE);
723cacbd	129
1e133ab2 MS	130	if (current->active_mm == mm) {
	131	clear_user_asce();
	132	__tlb_flush_mm(mm);
	133	}
723cacbd GS	134
	135	pgd = mm->pgd;
	136	mm->pgd = (pgd_t ) (pgd_val(pgd) & _REGION_ENTRY_ORIGIN);
f1c1174f	137	mm->context.asce_limit = _REGION3_SIZE;
723cacbd GS	138	mm->context.asce = __pa(mm->pgd) \| _ASCE_TABLE_LENGTH \|
723cacbd GS	139	_ASCE_USER_BITS \| _ASCE_TYPE_SEGMENT;
723cacbd GS	140	crst_table_free(mm, (unsigned long *) pgd);
723cacbd GS	141
1e133ab2 MS	142	if (current->active_mm == mm)
	143	set_user_asce(mm);
	144	}
	145
	146	static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits)
	147	{
	148	unsigned int old, new;
	149
	150	do {
	151	old = atomic_read(v);
	152	new = old ^ bits;
	153	} while (atomic_cmpxchg(v, old, new) != old);
	154	return new;
	155	}
	156
4be130a0 MS	157	#ifdef CONFIG_PGSTE
	158
	159	struct page page_table_alloc_pgste(struct mm_struct mm)
	160	{
	161	struct page *page;
	162	unsigned long *table;
	163
faee35a5	164	page = alloc_page(GFP_KERNEL);
4be130a0 MS	165	if (page) {
	166	table = (unsigned long *) page_to_phys(page);
	167	clear_table(table, _PAGE_INVALID, PAGE_SIZE/2);
	168	clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2);
	169	}
	170	return page;
	171	}
	172
	173	void page_table_free_pgste(struct page *page)
	174	{
	175	__free_page(page);
	176	}
	177
	178	#endif /* CONFIG_PGSTE */
	179
1e133ab2 MS	180	/*
	181	* page table entry allocation/free routines.
	182	*/
	183	unsigned long page_table_alloc(struct mm_struct mm)
	184	{
	185	unsigned long *table;
	186	struct page *page;
	187	unsigned int mask, bit;
	188
	189	/* Try to get a fragment of a 4K page as a 2K page table */
	190	if (!mm_alloc_pgste(mm)) {
	191	table = NULL;
f28a4b4d	192	spin_lock_bh(&mm->context.lock);
1e133ab2 MS	193	if (!list_empty(&mm->context.pgtable_list)) {
	194	page = list_first_entry(&mm->context.pgtable_list,
	195	struct page, lru);
	196	mask = atomic_read(&page->_mapcount);
	197	mask = (mask \| (mask >> 4)) & 3;
	198	if (mask != 3) {
	199	table = (unsigned long *) page_to_phys(page);
	200	bit = mask & 1; /* =1 -> second 2K */
	201	if (bit)
	202	table += PTRS_PER_PTE;
	203	atomic_xor_bits(&page->_mapcount, 1U << bit);
	204	list_del(&page->lru);
	205	}
	206	}
f28a4b4d	207	spin_unlock_bh(&mm->context.lock);
1e133ab2 MS	208	if (table)
	209	return table;
	210	}
	211	/* Allocate a fresh page */
10d58bf2	212	page = alloc_page(GFP_KERNEL);
1e133ab2 MS	213	if (!page)
	214	return NULL;
	215	if (!pgtable_page_ctor(page)) {
	216	__free_page(page);
	217	return NULL;
	218	}
c9b5ad54	219	arch_set_page_dat(page, 0);
1e133ab2 MS	220	/* Initialize page table */
	221	table = (unsigned long *) page_to_phys(page);
	222	if (mm_alloc_pgste(mm)) {
	223	/* Return 4K page table with PGSTEs */
	224	atomic_set(&page->_mapcount, 3);
	225	clear_table(table, _PAGE_INVALID, PAGE_SIZE/2);
	226	clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2);
	227	} else {
	228	/* Return the first 2K fragment of the page */
	229	atomic_set(&page->_mapcount, 1);
	230	clear_table(table, _PAGE_INVALID, PAGE_SIZE);
f28a4b4d	231	spin_lock_bh(&mm->context.lock);
1e133ab2	232	list_add(&page->lru, &mm->context.pgtable_list);
f28a4b4d	233	spin_unlock_bh(&mm->context.lock);
1e133ab2 MS	234	}
	235	return table;
	236	}
	237
	238	void page_table_free(struct mm_struct mm, unsigned long table)
	239	{
	240	struct page *page;
	241	unsigned int bit, mask;
	242
	243	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
	244	if (!mm_alloc_pgste(mm)) {
	245	/* Free 2K page table fragment of a 4K page */
	246	bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t));
f28a4b4d	247	spin_lock_bh(&mm->context.lock);
1e133ab2 MS	248	mask = atomic_xor_bits(&page->_mapcount, 1U << bit);
	249	if (mask & 3)
	250	list_add(&page->lru, &mm->context.pgtable_list);
	251	else
	252	list_del(&page->lru);
f28a4b4d	253	spin_unlock_bh(&mm->context.lock);
1e133ab2 MS	254	if (mask != 0)
	255	return;
	256	}
	257
	258	pgtable_page_dtor(page);
	259	atomic_set(&page->_mapcount, -1);
	260	__free_page(page);
	261	}
	262
	263	void page_table_free_rcu(struct mmu_gather tlb, unsigned long table,
	264	unsigned long vmaddr)
	265	{
	266	struct mm_struct *mm;
	267	struct page *page;
	268	unsigned int bit, mask;
	269
	270	mm = tlb->mm;
	271	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
	272	if (mm_alloc_pgste(mm)) {
	273	gmap_unlink(mm, table, vmaddr);
	274	table = (unsigned long *) (__pa(table) \| 3);
	275	tlb_remove_table(tlb, table);
	276	return;
	277	}
	278	bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t));
f28a4b4d	279	spin_lock_bh(&mm->context.lock);
1e133ab2 MS	280	mask = atomic_xor_bits(&page->_mapcount, 0x11U << bit);
	281	if (mask & 3)
	282	list_add_tail(&page->lru, &mm->context.pgtable_list);
	283	else
	284	list_del(&page->lru);
f28a4b4d	285	spin_unlock_bh(&mm->context.lock);
1e133ab2 MS	286	table = (unsigned long *) (__pa(table) \| (1U << bit));
	287	tlb_remove_table(tlb, table);
	288	}
	289
	290	static void __tlb_remove_table(void *_table)
	291	{
	292	unsigned int mask = (unsigned long) _table & 3;
	293	void table = (void )((unsigned long) _table ^ mask);
	294	struct page *page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
	295
	296	switch (mask) {
1aea9b3f	297	case 0: /* pmd, pud, or p4d */
1e133ab2 MS	298	free_pages((unsigned long) table, 2);
	299	break;
	300	case 1: /* lower 2K of a 4K page table */
	301	case 2: /* higher 2K of a 4K page table */
	302	if (atomic_xor_bits(&page->_mapcount, mask << 4) != 0)
	303	break;
	304	/* fallthrough */
	305	case 3: /* 4K page table with pgstes */
	306	pgtable_page_dtor(page);
	307	atomic_set(&page->_mapcount, -1);
	308	__free_page(page);
	309	break;
	310	}
	311	}
	312
	313	static void tlb_remove_table_smp_sync(void *arg)
	314	{
	315	/* Simply deliver the interrupt */
	316	}
	317
	318	static void tlb_remove_table_one(void *table)
	319	{
	320	/*
	321	* This isn't an RCU grace period and hence the page-tables cannot be
	322	* assumed to be actually RCU-freed.
	323	*
	324	* It is however sufficient for software page-table walkers that rely
	325	* on IRQ disabling. See the comment near struct mmu_table_batch.
	326	*/
	327	smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
	328	__tlb_remove_table(table);
	329	}
	330
	331	static void tlb_remove_table_rcu(struct rcu_head *head)
	332	{
	333	struct mmu_table_batch *batch;
	334	int i;
	335
	336	batch = container_of(head, struct mmu_table_batch, rcu);
	337
	338	for (i = 0; i < batch->nr; i++)
	339	__tlb_remove_table(batch->tables[i]);
	340
	341	free_page((unsigned long)batch);
	342	}
	343
	344	void tlb_table_flush(struct mmu_gather *tlb)
	345	{
	346	struct mmu_table_batch **batch = &tlb->batch;
	347
	348	if (*batch) {
	349	call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
	350	*batch = NULL;
	351	}
	352	}
	353
	354	void tlb_remove_table(struct mmu_gather tlb, void table)
	355	{
	356	struct mmu_table_batch **batch = &tlb->batch;
	357
	358	tlb->mm->context.flush_mm = 1;
	359	if (*batch == NULL) {
	360	batch = (struct mmu_table_batch )
	361	__get_free_page(GFP_NOWAIT \| __GFP_NOWARN);
362	if (*batch == NULL) {
363	__tlb_flush_mm_lazy(tlb->mm);
364	tlb_remove_table_one(table);
365	return;
366	}
367	(*batch)->nr = 0;
368	}
369	(batch)->tables[(batch)->nr++] = table;
370	if ((*batch)->nr == MAX_TABLE_BATCH)
371	tlb_flush_mmu(tlb);
372	}