arch/csky/kernel/vdso.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
   3
   4 #include <linux/binfmts.h>
   5 #include <linux/elf.h>
   6 #include <linux/err.h>
   7 #include <linux/mm.h>
   8 #include <linux/slab.h>
   9
  10 #include <asm/page.h>
  11 #include <vdso/datapage.h>
  12
  13 extern char vdso_start[], vdso_end[];
  14
  15 static unsigned int vdso_pages;
  16 static struct page **vdso_pagelist;
  17
  18 static union vdso_data_store vdso_data_store __page_aligned_data;
  19 struct vdso_data *vdso_data = vdso_data_store.data;
  20
  21 static int __init vdso_init(void)
  22 {
  23         unsigned int i;
  24
  25         vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
  26         vdso_pagelist =
  27                 kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
  28         if (unlikely(vdso_pagelist == NULL)) {
  29                 pr_err("vdso: pagelist allocation failed\n");
  30                 return -ENOMEM;
  31         }
  32
  33         for (i = 0; i < vdso_pages; i++) {
  34                 struct page *pg;
  35
  36                 pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
  37                 vdso_pagelist[i] = pg;
  38         }
  39         vdso_pagelist[i] = virt_to_page(vdso_data);
  40
  41         return 0;
  42 }
  43 arch_initcall(vdso_init);
  44
  45 int arch_setup_additional_pages(struct linux_binprm *bprm,
  46         int uses_interp)
  47 {
  48         struct vm_area_struct *vma;
  49         struct mm_struct *mm = current->mm;
  50         unsigned long vdso_base, vdso_len;
  51         int ret;
  52         static struct vm_special_mapping vdso_mapping = {
  53                 .name = "[vdso]",
  54         };
  55         static struct vm_special_mapping vvar_mapping = {
  56                 .name = "[vvar]",
  57         };
  58
  59         vdso_len = (vdso_pages + 1) << PAGE_SHIFT;
  60
  61         mmap_write_lock(mm);
  62         vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
  63         if (IS_ERR_VALUE(vdso_base)) {
  64                 ret = vdso_base;
  65                 goto end;
  66         }
  67
  68         /*
  69          * Put vDSO base into mm struct. We need to do this before calling
  70          * install_special_mapping or the perf counter mmap tracking code
  71          * will fail to recognise it as a vDSO (since arch_vma_name fails).
  72          */
  73         mm->context.vdso = (void *)vdso_base;
  74
  75         vdso_mapping.pages = vdso_pagelist;
  76         vma =
  77            _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
  78                 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
  79                 &vdso_mapping);
  80
  81         if (IS_ERR(vma)) {
  82                 ret = PTR_ERR(vma);
  83                 mm->context.vdso = NULL;
  84                 goto end;
  85         }
  86
  87         vdso_base += (vdso_pages << PAGE_SHIFT);
  88         vvar_mapping.pages = &vdso_pagelist[vdso_pages];
  89         vma = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
  90                 (VM_READ | VM_MAYREAD), &vvar_mapping);
  91
  92         if (IS_ERR(vma)) {
  93                 ret = PTR_ERR(vma);
  94                 mm->context.vdso = NULL;
  95                 goto end;
  96         }
  97         ret = 0;
  98 end:
  99         mmap_write_unlock(mm);
 100         return ret;
 101 }
 102
 103 const char *arch_vma_name(struct vm_area_struct *vma)
 104 {
 105         if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso))
 106                 return "[vdso]";
 107         if (vma->vm_mm && (vma->vm_start ==
 108                            (long)vma->vm_mm->context.vdso + PAGE_SIZE))
 109                 return "[vdso_data]";
 110         return NULL;
 111 }