1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * PGD allocation/freeing
4  *
5  * Copyright (C) 2012 ARM Ltd.
6  * Author: Catalin Marinas <catalin.marinas@arm.com>
7  */
8 
9 #include <linux/mm.h>
10 #include <linux/gfp.h>
11 #include <linux/highmem.h>
12 #include <linux/slab.h>
13 
14 #include <asm/pgalloc.h>
15 #include <asm/page.h>
16 #include <asm/tlbflush.h>
17 
18 static struct kmem_cache *pgd_cache __ro_after_init;
19 
pgd_alloc(struct mm_struct * mm)20 pgd_t *pgd_alloc(struct mm_struct *mm)
21 {
22 	gfp_t gfp = GFP_PGTABLE_USER;
23 
24 	if (PGD_SIZE == PAGE_SIZE)
25 		return (pgd_t *)__get_free_page(gfp);
26 	else
27 		return kmem_cache_alloc(pgd_cache, gfp);
28 }
29 
pgd_free(struct mm_struct * mm,pgd_t * pgd)30 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
31 {
32 	if (PGD_SIZE == PAGE_SIZE)
33 		free_page((unsigned long)pgd);
34 	else
35 		kmem_cache_free(pgd_cache, pgd);
36 }
37 
pgtable_cache_init(void)38 void __init pgtable_cache_init(void)
39 {
40 	if (PGD_SIZE == PAGE_SIZE)
41 		return;
42 
43 #ifdef CONFIG_ARM64_PA_BITS_52
44 	/*
45 	 * With 52-bit physical addresses, the architecture requires the
46 	 * top-level table to be aligned to at least 64 bytes.
47 	 */
48 	BUILD_BUG_ON(PGD_SIZE < 64);
49 #endif
50 
51 	/*
52 	 * Naturally aligned pgds required by the architecture.
53 	 */
54 	pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_SIZE,
55 				      SLAB_PANIC, NULL);
56 }
57