LXR linux/arch/powerpc/mm/pageattr.c

   1// SPDX-License-Identifier: GPL-2.0
   2
   3/*
   4 * MMU-generic set_memory implementation for powerpc
   5 *
   6 * Copyright 2019-2021, IBM Corporation.
   7 */
   8
   9#include <linux/mm.h>
  10#include <linux/vmalloc.h>
  11#include <linux/set_memory.h>
  12
  13#include <asm/mmu.h>
  14#include <asm/page.h>
  15#include <asm/pgtable.h>
  16
  17
  18/*
  19 * Updates the attributes of a page in three steps:
  20 *
  21 * 1. take the page_table_lock
  22 * 2. install the new entry with the updated attributes
  23 * 3. flush the TLB
  24 *
  25 * This sequence is safe against concurrent updates, and also allows updating the
  26 * attributes of a page currently being executed or accessed.
  27 */
  28static int change_page_attr(pte_t *ptep, unsigned long addr, void *data)
  29{
  30        long action = (long)data;
  31        pte_t pte;
  32
  33        spin_lock(&init_mm.page_table_lock);
  34
  35        pte = ptep_get(ptep);
  36
  37        /* modify the PTE bits as desired, then apply */
  38        switch (action) {
  39        case SET_MEMORY_RO:
  40                pte = pte_wrprotect(pte);
  41                break;
  42        case SET_MEMORY_RW:
  43                pte = pte_mkwrite(pte_mkdirty(pte));
  44                break;
  45        case SET_MEMORY_NX:
  46                pte = pte_exprotect(pte);
  47                break;
  48        case SET_MEMORY_X:
  49                pte = pte_mkexec(pte);
  50                break;
  51        default:
  52                WARN_ON_ONCE(1);
  53                break;
  54        }
  55
  56        pte_update(&init_mm, addr, ptep, ~0UL, pte_val(pte), 0);
  57
  58        /* See ptesync comment in radix__set_pte_at() */
  59        if (radix_enabled())
  60                asm volatile("ptesync": : :"memory");
  61
  62        flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
  63
  64        spin_unlock(&init_mm.page_table_lock);
  65
  66        return 0;
  67}
  68
  69int change_memory_attr(unsigned long addr, int numpages, long action)
  70{
  71        unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE);
  72        unsigned long size = numpages * PAGE_SIZE;
  73
  74        if (!numpages)
  75                return 0;
  76
  77        if (WARN_ON_ONCE(is_vmalloc_or_module_addr((void *)addr) &&
  78                         is_vm_area_hugepages((void *)addr)))
  79                return -EINVAL;
  80
  81#ifdef CONFIG_PPC_BOOK3S_64
  82        /*
  83         * On hash, the linear mapping is not in the Linux page table so
  84         * apply_to_existing_page_range() will have no effect. If in the future
  85         * the set_memory_* functions are used on the linear map this will need
  86         * to be updated.
  87         */
  88        if (!radix_enabled()) {
  89                int region = get_region_id(addr);
  90
  91                if (WARN_ON_ONCE(region != VMALLOC_REGION_ID && region != IO_REGION_ID))
  92                        return -EINVAL;
  93        }
  94#endif
  95
  96        return apply_to_existing_page_range(&init_mm, start, size,
  97                                            change_page_attr, (void *)action);
  98}
  99
 100/*
 101 * Set the attributes of a page:
 102 *
 103 * This function is used by PPC32 at the end of init to set final kernel memory
 104 * protection. It includes changing the maping of the page it is executing from
 105 * and data pages it is using.
 106 */
 107static int set_page_attr(pte_t *ptep, unsigned long addr, void *data)
 108{
 109        pgprot_t prot = __pgprot((unsigned long)data);
 110
 111        spin_lock(&init_mm.page_table_lock);
 112
 113        set_pte_at(&init_mm, addr, ptep, pte_modify(*ptep, prot));
 114        flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
 115
 116        spin_unlock(&init_mm.page_table_lock);
 117
 118        return 0;
 119}
 120
 121int set_memory_attr(unsigned long addr, int numpages, pgprot_t prot)
 122{
 123        unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE);
 124        unsigned long sz = numpages * PAGE_SIZE;
 125
 126        if (numpages <= 0)
 127                return 0;
 128
 129        return apply_to_existing_page_range(&init_mm, start, sz, set_page_attr,
 130                                            (void *)pgprot_val(prot));
 131}
 132