arch/x86/um/mem_32.c

   1 /*
   2  * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
   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 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/mm.h>
  10 #include <asm/page.h>
  11 #include <asm/mman.h>
  12
  13 static struct vm_area_struct gate_vma;
  14
  15 static int __init gate_vma_init(void)
  16 {
  17         if (!FIXADDR_USER_START)
  18                 return 0;
  19
  20         gate_vma.vm_mm = NULL;
  21         gate_vma.vm_start = FIXADDR_USER_START;
  22         gate_vma.vm_end = FIXADDR_USER_END;
  23         gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
  24         gate_vma.vm_page_prot = __P101;
  25
  26         /*
  27          * Make sure the vDSO gets into every core dump.
  28          * Dumping its contents makes post-mortem fully interpretable later
  29          * without matching up the same kernel and hardware config to see
  30          * what PC values meant.
  31          */
  32         gate_vma.vm_flags |= VM_ALWAYSDUMP;
  33
  34         return 0;
  35 }
  36 __initcall(gate_vma_init);
  37
  38 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
  39 {
  40         return FIXADDR_USER_START ? &gate_vma : NULL;
  41 }
  42
  43 int in_gate_area_no_mm(unsigned long addr)
  44 {
  45         if (!FIXADDR_USER_START)
  46                 return 0;
  47
  48         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
  49                 return 1;
  50
  51         return 0;
  52 }
  53
  54 int in_gate_area(struct mm_struct *mm, unsigned long addr)
  55 {
  56         struct vm_area_struct *vma = get_gate_vma(mm);
  57
  58         if (!vma)
  59                 return 0;
  60
  61         return (addr >= vma->vm_start) && (addr < vma->vm_end);
  62 }