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
20 static bool pgdir_is_page_size(void)
21 {
22 if (PGD_SIZE == PAGE_SIZE)
23 return true;
24 if (CONFIG_PGTABLE_LEVELS == 4)
25 return !pgtable_l4_enabled();
26 if (CONFIG_PGTABLE_LEVELS == 5)
27 return !pgtable_l5_enabled();
28 return false;
29 }
30
31 pgd_t *pgd_alloc(struct mm_struct *mm)
32 {
33 gfp_t gfp = GFP_PGTABLE_USER;
34
35 if (pgdir_is_page_size())
36 return (pgd_t *)__get_free_page(gfp);
37 else
38 return kmem_cache_alloc(pgd_cache, gfp);
39 }
40
41 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
42 {
43 if (pgdir_is_page_size())
44 free_page((unsigned long)pgd);
45 else
46 kmem_cache_free(pgd_cache, pgd);
47 }
48
49 void __init pgtable_cache_init(void)
50 {
51 if (pgdir_is_page_size())
52 return;
53
54 #ifdef CONFIG_ARM64_PA_BITS_52
55 /*
56 * With 52-bit physical addresses, the architecture requires the
57 * top-level table to be aligned to at least 64 bytes.
58 */
59 BUILD_BUG_ON(PGD_SIZE < 64);
60 #endif
61
62 /*
63 * Naturally aligned pgds required by the architecture.
64 */
65 pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_SIZE,
66 SLAB_PANIC, NULL);
67 }
68
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