linux/arch/hexagon/include/asm/pgalloc.h
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   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        pgtable_pte_page_dtor((pte));           \
  93        tlb_remove_page((tlb), (pte));          \
  94} while (0)
  95
  96#endif
  97