arch/arm/mm/pageattr.c

   1 /*
   2  * Copyright (c) 2014, The Linux Foundation. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 and
   6  * only version 2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13 #include <linux/mm.h>
  14 #include <linux/module.h>
  15
  16 #include <asm/pgtable.h>
  17 #include <asm/tlbflush.h>
  18
  19 struct page_change_data {
  20         pgprot_t set_mask;
  21         pgprot_t clear_mask;
  22 };
  23
  24 static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr,
  25                         void *data)
  26 {
  27         struct page_change_data *cdata = data;
  28         pte_t pte = *ptep;
  29
  30         pte = clear_pte_bit(pte, cdata->clear_mask);
  31         pte = set_pte_bit(pte, cdata->set_mask);
  32
  33         set_pte_ext(ptep, pte, 0);
  34         return 0;
  35 }
  36
  37 static bool in_range(unsigned long start, unsigned long size,
  38         unsigned long range_start, unsigned long range_end)
  39 {
  40         return start >= range_start && start < range_end &&
  41                 size <= range_end - start;
  42 }
  43
  44 static int change_memory_common(unsigned long addr, int numpages,
  45                                 pgprot_t set_mask, pgprot_t clear_mask)
  46 {
  47         unsigned long start = addr & PAGE_MASK;
  48         unsigned long end = PAGE_ALIGN(addr) + numpages * PAGE_SIZE;
  49         unsigned long size = end - start;
  50         int ret;
  51         struct page_change_data data;
  52
  53         WARN_ON_ONCE(start != addr);
  54
  55         if (!size)
  56                 return 0;
  57
  58         if (!in_range(start, size, MODULES_VADDR, MODULES_END) &&
  59             !in_range(start, size, VMALLOC_START, VMALLOC_END))
  60                 return -EINVAL;
  61
  62         data.set_mask = set_mask;
  63         data.clear_mask = clear_mask;
  64
  65         ret = apply_to_page_range(&init_mm, start, size, change_page_range,
  66                                         &data);
  67
  68         flush_tlb_kernel_range(start, end);
  69         return ret;
  70 }
  71
  72 int set_memory_ro(unsigned long addr, int numpages)
  73 {
  74         return change_memory_common(addr, numpages,
  75                                         __pgprot(L_PTE_RDONLY),
  76                                         __pgprot(0));
  77 }
  78
  79 int set_memory_rw(unsigned long addr, int numpages)
  80 {
  81         return change_memory_common(addr, numpages,
  82                                         __pgprot(0),
  83                                         __pgprot(L_PTE_RDONLY));
  84 }
  85
  86 int set_memory_nx(unsigned long addr, int numpages)
  87 {
  88         return change_memory_common(addr, numpages,
  89                                         __pgprot(L_PTE_XN),
  90                                         __pgprot(0));
  91 }
  92
  93 int set_memory_x(unsigned long addr, int numpages)
  94 {
  95         return change_memory_common(addr, numpages,
  96                                         __pgprot(0),
  97                                         __pgprot(L_PTE_XN));
  98 }