[mirror_ubuntu-jammy-kernel.git] / arch / s390 / mm / pgalloc.c

/*
 *  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.pgtable_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.pgtable_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.pgtable_lock);
		list_add(&page->lru, &mm->context.pgtable_list);
		spin_unlock_bh(&mm->context.pgtable_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.pgtable_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.pgtable_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.pgtable_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.pgtable_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
1e133ab2 MS	1	/*
	2	* Page table allocation functions
	3	*
	4	* Copyright IBM Corp. 2016
	5	* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
	6	*/
	7
	8	#include <linux/mm.h>
	9	#include <linux/sysctl.h>
	10	#include <asm/mmu_context.h>
	11	#include <asm/pgalloc.h>
	12	#include <asm/gmap.h>
	13	#include <asm/tlb.h>
	14	#include <asm/tlbflush.h>
	15
	16	#ifdef CONFIG_PGSTE
	17
	18	static int page_table_allocate_pgste_min = 0;
	19	static int page_table_allocate_pgste_max = 1;
	20	int page_table_allocate_pgste = 0;
	21	EXPORT_SYMBOL(page_table_allocate_pgste);
	22
	23	static struct ctl_table page_table_sysctl[] = {
	24	{
	25	.procname = "allocate_pgste",
	26	.data = &page_table_allocate_pgste,
	27	.maxlen = sizeof(int),
	28	.mode = S_IRUGO \| S_IWUSR,
	29	.proc_handler = proc_dointvec,
	30	.extra1 = &page_table_allocate_pgste_min,
	31	.extra2 = &page_table_allocate_pgste_max,
	32	},
	33	{ }
	34	};
	35
	36	static struct ctl_table page_table_sysctl_dir[] = {
	37	{
	38	.procname = "vm",
	39	.maxlen = 0,
	40	.mode = 0555,
	41	.child = page_table_sysctl,
	42	},
	43	{ }
	44	};
	45
	46	static int __init page_table_register_sysctl(void)
	47	{
	48	return register_sysctl_table(page_table_sysctl_dir) ? 0 : -ENOMEM;
	49	}
	50	__initcall(page_table_register_sysctl);
	51
	52	#endif /* CONFIG_PGSTE */
	53
	54	unsigned long crst_table_alloc(struct mm_struct mm)
	55	{
	56	struct page *page = alloc_pages(GFP_KERNEL, 2);
	57
	58	if (!page)
	59	return NULL;
c9b5ad54	60	arch_set_page_dat(page, 2);
1e133ab2 MS	61	return (unsigned long *) page_to_phys(page);
	62	}
	63
	64	void crst_table_free(struct mm_struct mm, unsigned long table)
	65	{
	66	free_pages((unsigned long) table, 2);
	67	}
	68
	69	static void __crst_table_upgrade(void *arg)
	70	{
	71	struct mm_struct *mm = arg;
	72
	73	if (current->active_mm == mm) {
	74	clear_user_asce();
	75	set_user_asce(mm);
	76	}
	77	__tlb_flush_local();
	78	}
	79
1aea9b3f	80	int crst_table_upgrade(struct mm_struct *mm, unsigned long end)
1e133ab2 MS	81	{
1e133ab2 MS	82	unsigned long table, pgd;
1aea9b3f	83	int rc, notify;
1e133ab2	84
1aea9b3f	85	/* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */
2fc4876e	86	VM_BUG_ON(mm->context.asce_limit < _REGION2_SIZE);
1aea9b3f	87	if (end >= TASK_SIZE_MAX)
1e133ab2	88	return -ENOMEM;
1aea9b3f MS	89	rc = 0;
	90	notify = 0;
	91	while (mm->context.asce_limit < end) {
	92	table = crst_table_alloc(mm);
	93	if (!table) {
	94	rc = -ENOMEM;
	95	break;
	96	}
	97	spin_lock_bh(&mm->page_table_lock);
	98	pgd = (unsigned long *) mm->pgd;
f1c1174f	99	if (mm->context.asce_limit == _REGION2_SIZE) {
1aea9b3f MS	100	crst_table_init(table, _REGION2_ENTRY_EMPTY);
	101	p4d_populate(mm, (p4d_t ) table, (pud_t ) pgd);
	102	mm->pgd = (pgd_t *) table;
f1c1174f	103	mm->context.asce_limit = _REGION1_SIZE;
1aea9b3f MS	104	mm->context.asce = __pa(mm->pgd) \| _ASCE_TABLE_LENGTH \|
	105	_ASCE_USER_BITS \| _ASCE_TYPE_REGION2;
	106	} else {
	107	crst_table_init(table, _REGION1_ENTRY_EMPTY);
	108	pgd_populate(mm, (pgd_t ) table, (p4d_t ) pgd);
	109	mm->pgd = (pgd_t *) table;
	110	mm->context.asce_limit = -PAGE_SIZE;
	111	mm->context.asce = __pa(mm->pgd) \| _ASCE_TABLE_LENGTH \|
	112	_ASCE_USER_BITS \| _ASCE_TYPE_REGION1;
	113	}
	114	notify = 1;
	115	spin_unlock_bh(&mm->page_table_lock);
	116	}
	117	if (notify)
	118	on_each_cpu(__crst_table_upgrade, mm, 0);
	119	return rc;
1e133ab2 MS	120	}
1e133ab2 MS	121
723cacbd	122	void crst_table_downgrade(struct mm_struct *mm)
1e133ab2 MS	123	{
	124	pgd_t *pgd;
	125
723cacbd	126	/* downgrade should only happen from 3 to 2 levels (compat only) */
2fc4876e	127	VM_BUG_ON(mm->context.asce_limit != _REGION2_SIZE);
723cacbd	128
1e133ab2 MS	129	if (current->active_mm == mm) {
	130	clear_user_asce();
	131	__tlb_flush_mm(mm);
	132	}
723cacbd GS	133
	134	pgd = mm->pgd;
	135	mm->pgd = (pgd_t ) (pgd_val(pgd) & _REGION_ENTRY_ORIGIN);
f1c1174f	136	mm->context.asce_limit = _REGION3_SIZE;
723cacbd GS	137	mm->context.asce = __pa(mm->pgd) \| _ASCE_TABLE_LENGTH \|
723cacbd GS	138	_ASCE_USER_BITS \| _ASCE_TYPE_SEGMENT;
723cacbd GS	139	crst_table_free(mm, (unsigned long *) pgd);
723cacbd GS	140
1e133ab2 MS	141	if (current->active_mm == mm)
	142	set_user_asce(mm);
	143	}
	144
	145	static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits)
	146	{
	147	unsigned int old, new;
	148
	149	do {
	150	old = atomic_read(v);
	151	new = old ^ bits;
	152	} while (atomic_cmpxchg(v, old, new) != old);
	153	return new;
	154	}
	155
4be130a0 MS	156	#ifdef CONFIG_PGSTE
	157
	158	struct page page_table_alloc_pgste(struct mm_struct mm)
	159	{
	160	struct page *page;
	161	unsigned long *table;
	162
faee35a5	163	page = alloc_page(GFP_KERNEL);
4be130a0 MS	164	if (page) {
	165	table = (unsigned long *) page_to_phys(page);
	166	clear_table(table, _PAGE_INVALID, PAGE_SIZE/2);
	167	clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2);
	168	}
	169	return page;
	170	}
	171
	172	void page_table_free_pgste(struct page *page)
	173	{
	174	__free_page(page);
	175	}
	176
	177	#endif /* CONFIG_PGSTE */
	178
1e133ab2 MS	179	/*
	180	* page table entry allocation/free routines.
	181	*/
	182	unsigned long page_table_alloc(struct mm_struct mm)
	183	{
	184	unsigned long *table;
	185	struct page *page;
	186	unsigned int mask, bit;
	187
	188	/* Try to get a fragment of a 4K page as a 2K page table */
	189	if (!mm_alloc_pgste(mm)) {
	190	table = NULL;
8ecb1a59	191	spin_lock_bh(&mm->context.pgtable_lock);
1e133ab2 MS	192	if (!list_empty(&mm->context.pgtable_list)) {
	193	page = list_first_entry(&mm->context.pgtable_list,
	194	struct page, lru);
	195	mask = atomic_read(&page->_mapcount);
	196	mask = (mask \| (mask >> 4)) & 3;
	197	if (mask != 3) {
	198	table = (unsigned long *) page_to_phys(page);
	199	bit = mask & 1; /* =1 -> second 2K */
	200	if (bit)
	201	table += PTRS_PER_PTE;
	202	atomic_xor_bits(&page->_mapcount, 1U << bit);
	203	list_del(&page->lru);
	204	}
	205	}
8ecb1a59	206	spin_unlock_bh(&mm->context.pgtable_lock);
1e133ab2 MS	207	if (table)
	208	return table;
	209	}
	210	/* Allocate a fresh page */
10d58bf2	211	page = alloc_page(GFP_KERNEL);
1e133ab2 MS	212	if (!page)
	213	return NULL;
	214	if (!pgtable_page_ctor(page)) {
	215	__free_page(page);
	216	return NULL;
	217	}
c9b5ad54	218	arch_set_page_dat(page, 0);
1e133ab2 MS	219	/* Initialize page table */
	220	table = (unsigned long *) page_to_phys(page);
	221	if (mm_alloc_pgste(mm)) {
	222	/* Return 4K page table with PGSTEs */
	223	atomic_set(&page->_mapcount, 3);
	224	clear_table(table, _PAGE_INVALID, PAGE_SIZE/2);
	225	clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2);
	226	} else {
	227	/* Return the first 2K fragment of the page */
	228	atomic_set(&page->_mapcount, 1);
	229	clear_table(table, _PAGE_INVALID, PAGE_SIZE);
8ecb1a59	230	spin_lock_bh(&mm->context.pgtable_lock);
1e133ab2	231	list_add(&page->lru, &mm->context.pgtable_list);
8ecb1a59	232	spin_unlock_bh(&mm->context.pgtable_lock);
1e133ab2 MS	233	}
	234	return table;
	235	}
	236
	237	void page_table_free(struct mm_struct mm, unsigned long table)
	238	{
	239	struct page *page;
	240	unsigned int bit, mask;
	241
	242	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
	243	if (!mm_alloc_pgste(mm)) {
	244	/* Free 2K page table fragment of a 4K page */
	245	bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t));
8ecb1a59	246	spin_lock_bh(&mm->context.pgtable_lock);
1e133ab2 MS	247	mask = atomic_xor_bits(&page->_mapcount, 1U << bit);
	248	if (mask & 3)
	249	list_add(&page->lru, &mm->context.pgtable_list);
	250	else
	251	list_del(&page->lru);
8ecb1a59	252	spin_unlock_bh(&mm->context.pgtable_lock);
1e133ab2 MS	253	if (mask != 0)
	254	return;
	255	}
	256
	257	pgtable_page_dtor(page);
	258	atomic_set(&page->_mapcount, -1);
	259	__free_page(page);
	260	}
	261
	262	void page_table_free_rcu(struct mmu_gather tlb, unsigned long table,
	263	unsigned long vmaddr)
	264	{
	265	struct mm_struct *mm;
	266	struct page *page;
	267	unsigned int bit, mask;
	268
	269	mm = tlb->mm;
	270	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
	271	if (mm_alloc_pgste(mm)) {
	272	gmap_unlink(mm, table, vmaddr);
	273	table = (unsigned long *) (__pa(table) \| 3);
	274	tlb_remove_table(tlb, table);
	275	return;
	276	}
	277	bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t));
8ecb1a59	278	spin_lock_bh(&mm->context.pgtable_lock);
1e133ab2 MS	279	mask = atomic_xor_bits(&page->_mapcount, 0x11U << bit);
	280	if (mask & 3)
	281	list_add_tail(&page->lru, &mm->context.pgtable_list);
	282	else
	283	list_del(&page->lru);
8ecb1a59	284	spin_unlock_bh(&mm->context.pgtable_lock);
1e133ab2 MS	285	table = (unsigned long *) (__pa(table) \| (1U << bit));
	286	tlb_remove_table(tlb, table);
	287	}
	288
	289	static void __tlb_remove_table(void *_table)
	290	{
	291	unsigned int mask = (unsigned long) _table & 3;
	292	void table = (void )((unsigned long) _table ^ mask);
	293	struct page *page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
	294
	295	switch (mask) {
1aea9b3f	296	case 0: /* pmd, pud, or p4d */
1e133ab2 MS	297	free_pages((unsigned long) table, 2);
	298	break;
	299	case 1: /* lower 2K of a 4K page table */
	300	case 2: /* higher 2K of a 4K page table */
	301	if (atomic_xor_bits(&page->_mapcount, mask << 4) != 0)
	302	break;
	303	/* fallthrough */
	304	case 3: /* 4K page table with pgstes */
	305	pgtable_page_dtor(page);
	306	atomic_set(&page->_mapcount, -1);
	307	__free_page(page);
	308	break;
	309	}
	310	}
	311
	312	static void tlb_remove_table_smp_sync(void *arg)
	313	{
	314	/* Simply deliver the interrupt */
	315	}
	316
	317	static void tlb_remove_table_one(void *table)
	318	{
	319	/*
	320	* This isn't an RCU grace period and hence the page-tables cannot be
	321	* assumed to be actually RCU-freed.
	322	*
	323	* It is however sufficient for software page-table walkers that rely
	324	* on IRQ disabling. See the comment near struct mmu_table_batch.
	325	*/
	326	smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
	327	__tlb_remove_table(table);
	328	}
	329
	330	static void tlb_remove_table_rcu(struct rcu_head *head)
	331	{
	332	struct mmu_table_batch *batch;
	333	int i;
	334
	335	batch = container_of(head, struct mmu_table_batch, rcu);
	336
	337	for (i = 0; i < batch->nr; i++)
	338	__tlb_remove_table(batch->tables[i]);
	339
	340	free_page((unsigned long)batch);
	341	}
	342
	343	void tlb_table_flush(struct mmu_gather *tlb)
	344	{
	345	struct mmu_table_batch **batch = &tlb->batch;
	346
	347	if (*batch) {
	348	call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
	349	*batch = NULL;
	350	}
	351	}
	352
	353	void tlb_remove_table(struct mmu_gather tlb, void table)
	354	{
	355	struct mmu_table_batch **batch = &tlb->batch;
	356
	357	tlb->mm->context.flush_mm = 1;
	358	if (*batch == NULL) {
	359	batch = (struct mmu_table_batch )
	360	__get_free_page(GFP_NOWAIT \| __GFP_NOWARN);
361	if (*batch == NULL) {
362	__tlb_flush_mm_lazy(tlb->mm);
363	tlb_remove_table_one(table);
364	return;
365	}
366	(*batch)->nr = 0;
367	}
368	(batch)->tables[(batch)->nr++] = table;
369	if ((*batch)->nr == MAX_TABLE_BATCH)
370	tlb_flush_mmu(tlb);
371	}