1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Page table support for the Hexagon architecture
4 *
5 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
6 */
7
8#ifndef _ASM_PGALLOC_H
9#define _ASM_PGALLOC_H
10
11#include <asm/mem-layout.h>
12#include <asm/atomic.h>
13
14#include <asm-generic/pgalloc.h>
15
16extern unsigned long long kmap_generation;
17
18/*
19 * Page table creation interface
20 */
21static inline pgd_t *pgd_alloc(struct mm_struct *mm)
22{
23	pgd_t *pgd;
24
25	pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
26
27	/*
28	 * There may be better ways to do this, but to ensure
29	 * that new address spaces always contain the kernel
30	 * base mapping, and to ensure that the user area is
31	 * initially marked invalid, initialize the new map
32	 * map with a copy of the kernel's persistent map.
33	 */
34
35	memcpy(pgd, swapper_pg_dir, PTRS_PER_PGD*sizeof(pgd_t));
36	mm->context.generation = kmap_generation;
37
38	/* Physical version is what is passed to virtual machine on switch */
39	mm->context.ptbase = __pa(pgd);
40
41	return pgd;
42}
43
44static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
45				pgtable_t pte)
46{
47	/*
48	 * Conveniently, zero in 3 LSB means indirect 4K page table.
49	 * Not so convenient when you're trying to vary the page size.
50	 */
51	set_pmd(pmd, __pmd(((unsigned long)page_to_pfn(pte) << PAGE_SHIFT) |
52		HEXAGON_L1_PTE_SIZE));
53}
54
55/*
56 * Other architectures seem to have ways of making all processes
57 * share the same pmd's for their kernel mappings, but the v0.3
58 * Hexagon VM spec has a "monolithic" L1 table for user and kernel
59 * segments.  We track "generations" of the kernel map to minimize
60 * overhead, and update the "slave" copies of the kernel mappings
61 * as part of switch_mm.  However, we still need to update the
62 * kernel map of the active thread who's calling pmd_populate_kernel...
63 */
64static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
65				       pte_t *pte)
66{
67	extern spinlock_t kmap_gen_lock;
68	pmd_t *ppmd;
69	int pmdindex;
70
71	spin_lock(&kmap_gen_lock);
72	kmap_generation++;
73	mm->context.generation = kmap_generation;
74	current->active_mm->context.generation = kmap_generation;
75	spin_unlock(&kmap_gen_lock);
76
77	set_pmd(pmd, __pmd(((unsigned long)__pa(pte)) | HEXAGON_L1_PTE_SIZE));
78
79	/*
80	 * Now the "slave" copy of the current thread.
81	 * This is pointer arithmetic, not byte addresses!
82	 */
83	pmdindex = (pgd_t *)pmd - mm->pgd;
84	ppmd = (pmd_t *)current->active_mm->pgd + pmdindex;
85	set_pmd(ppmd, __pmd(((unsigned long)__pa(pte)) | HEXAGON_L1_PTE_SIZE));
86	if (pmdindex > max_kernel_seg)
87		max_kernel_seg = pmdindex;
88}
89
90#define __pte_free_tlb(tlb, pte, addr)				\
91do {								\
92	pagetable_pte_dtor((page_ptdesc(pte)));			\
93	tlb_remove_page_ptdesc((tlb), (page_ptdesc(pte)));	\
94} while (0)
95
96#endif
97