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 #include <asm/set_memory.h>
  19
  20 struct page_change_data {
  21         pgprot_t set_mask;
  22         pgprot_t clear_mask;
  23 };
  24
  25 static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr,
  26                         void *data)
  27 {
  28         struct page_change_data *cdata = data;
  29         pte_t pte = *ptep;
  30
  31         pte = clear_pte_bit(pte, cdata->clear_mask);
  32         pte = set_pte_bit(pte, cdata->set_mask);
  33
  34         set_pte_ext(ptep, pte, 0);
  35         return 0;
  36 }
  37
  38 static bool in_range(unsigned long start, unsigned long size,
  39         unsigned long range_start, unsigned long range_end)
  40 {
  41         return start >= range_start && start < range_end &&
  42                 size <= range_end - start;
  43 }
  44
  45 static int change_memory_common(unsigned long addr, int numpages,
  46                                 pgprot_t set_mask, pgprot_t clear_mask)
  47 {
  48         unsigned long start = addr & PAGE_MASK;
  49         unsigned long end = PAGE_ALIGN(addr) + numpages * PAGE_SIZE;
  50         unsigned long size = end - start;
  51         int ret;
  52         struct page_change_data data;
  53
  54         WARN_ON_ONCE(start != addr);
  55
  56         if (!size)
  57                 return 0;
  58
  59         if (!in_range(start, size, MODULES_VADDR, MODULES_END) &&
  60             !in_range(start, size, VMALLOC_START, VMALLOC_END))
  61                 return -EINVAL;
  62
  63         data.set_mask = set_mask;
  64         data.clear_mask = clear_mask;
  65
  66         ret = apply_to_page_range(&init_mm, start, size, change_page_range,
  67                                         &data);
  68
  69         flush_tlb_kernel_range(start, end);
  70         return ret;
  71 }
  72
  73 int set_memory_ro(unsigned long addr, int numpages)
  74 {
  75         return change_memory_common(addr, numpages,
  76                                         __pgprot(L_PTE_RDONLY),
  77                                         __pgprot(0));
  78 }
  79
  80 int set_memory_rw(unsigned long addr, int numpages)
  81 {
  82         return change_memory_common(addr, numpages,
  83                                         __pgprot(0),
  84                                         __pgprot(L_PTE_RDONLY));
  85 }
  86
  87 int set_memory_nx(unsigned long addr, int numpages)
  88 {
  89         return change_memory_common(addr, numpages,
  90                                         __pgprot(L_PTE_XN),
  91                                         __pgprot(0));
  92 }
  93
  94 int set_memory_x(unsigned long addr, int numpages)
  95 {
  96         return change_memory_common(addr, numpages,
  97                                         __pgprot(0),
  98                                         __pgprot(L_PTE_XN));
  99 }