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 int change_memory_common(unsigned long addr, int numpages,
  38                                 pgprot_t set_mask, pgprot_t clear_mask)
  39 {
  40         unsigned long start = addr;
  41         unsigned long size = PAGE_SIZE*numpages;
  42         unsigned long end = start + size;
  43         int ret;
  44         struct page_change_data data;
  45
  46         if (!IS_ALIGNED(addr, PAGE_SIZE)) {
  47                 start &= PAGE_MASK;
  48                 end = start + size;
  49                 WARN_ON_ONCE(1);
  50         }
  51
  52         if (!numpages)
  53                 return 0;
  54
  55         if (start < MODULES_VADDR || start >= MODULES_END)
  56                 return -EINVAL;
  57
  58         if (end < MODULES_VADDR || start >= MODULES_END)
  59                 return -EINVAL;
  60
  61         data.set_mask = set_mask;
  62         data.clear_mask = clear_mask;
  63
  64         ret = apply_to_page_range(&init_mm, start, size, change_page_range,
  65                                         &data);
  66
  67         flush_tlb_kernel_range(start, end);
  68         return ret;
  69 }
  70
  71 int set_memory_ro(unsigned long addr, int numpages)
  72 {
  73         return change_memory_common(addr, numpages,
  74                                         __pgprot(L_PTE_RDONLY),
  75                                         __pgprot(0));
  76 }
  77
  78 int set_memory_rw(unsigned long addr, int numpages)
  79 {
  80         return change_memory_common(addr, numpages,
  81                                         __pgprot(0),
  82                                         __pgprot(L_PTE_RDONLY));
  83 }
  84
  85 int set_memory_nx(unsigned long addr, int numpages)
  86 {
  87         return change_memory_common(addr, numpages,
  88                                         __pgprot(L_PTE_XN),
  89                                         __pgprot(0));
  90 }
  91
  92 int set_memory_x(unsigned long addr, int numpages)
  93 {
  94         return change_memory_common(addr, numpages,
  95                                         __pgprot(0),
  96                                         __pgprot(L_PTE_XN));
  97 }