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 <asm/vdso.h>
  12
  13 extern char vdso_start[], vdso_end[];
  14
  15 static unsigned int vdso_pages;
  16 static struct page **vdso_pagelist;
  17
  18 /*
  19  * The vDSO data page.
  20  */
  21 static union {
  22         struct vdso_data        data;
  23         u8                      page[PAGE_SIZE];
  24 } vdso_data_store __page_aligned_data;
  25 struct vdso_data *vdso_data = &vdso_data_store.data;
  26
  27 static int __init vdso_init(void)
  28 {
  29         unsigned int i;
  30
  31         vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
  32         vdso_pagelist =
  33                 kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
  34         if (unlikely(vdso_pagelist == NULL)) {
  35                 pr_err("vdso: pagelist allocation failed\n");
  36                 return -ENOMEM;
  37         }
  38
  39         for (i = 0; i < vdso_pages; i++) {
  40                 struct page *pg;
  41
  42                 pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
  43                 vdso_pagelist[i] = pg;
  44         }
  45         vdso_pagelist[i] = virt_to_page(vdso_data);
  46
  47         return 0;
  48 }
  49 arch_initcall(vdso_init);
  50
  51 int arch_setup_additional_pages(struct linux_binprm *bprm,
  52         int uses_interp)
  53 {
  54         struct mm_struct *mm = current->mm;
  55         unsigned long vdso_base, vdso_len;
  56         int ret;
  57
  58         vdso_len = (vdso_pages + 1) << PAGE_SHIFT;
  59
  60         mmap_write_lock(mm);
  61         vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
  62         if (IS_ERR_VALUE(vdso_base)) {
  63                 ret = vdso_base;
  64                 goto end;
  65         }
  66
  67         /*
  68          * Put vDSO base into mm struct. We need to do this before calling
  69          * install_special_mapping or the perf counter mmap tracking code
  70          * will fail to recognise it as a vDSO (since arch_vma_name fails).
  71          */
  72         mm->context.vdso = (void *)vdso_base;
  73
  74         ret =
  75            install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
  76                 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
  77                 vdso_pagelist);
  78
  79         if (unlikely(ret)) {
  80                 mm->context.vdso = NULL;
  81                 goto end;
  82         }
  83
  84         vdso_base += (vdso_pages << PAGE_SHIFT);
  85         ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
  86                 (VM_READ | VM_MAYREAD), &vdso_pagelist[vdso_pages]);
  87
  88         if (unlikely(ret))
  89                 mm->context.vdso = NULL;
  90 end:
  91         mmap_write_unlock(mm);
  92         return ret;
  93 }
  94
  95 const char *arch_vma_name(struct vm_area_struct *vma)
  96 {
  97         if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso))
  98                 return "[vdso]";
  99         if (vma->vm_mm && (vma->vm_start ==
 100                            (long)vma->vm_mm->context.vdso + PAGE_SIZE))
 101                 return "[vdso_data]";
 102         return NULL;
 103 }