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 #ifdef GENERIC_TIME_VSYSCALL
  12 #include <vdso/datapage.h>
  13 #else
  14 #include <asm/vdso.h>
  15 #endif
  16
  17 extern char vdso_start[], vdso_end[];
  18
  19 static unsigned int vdso_pages;
  20 static struct page **vdso_pagelist;
  21
  22 /*
  23  * The vDSO data page.
  24  */
  25 static union {
  26         struct vdso_data        data;
  27         u8                      page[PAGE_SIZE];
  28 } vdso_data_store __page_aligned_data;
  29 struct vdso_data *vdso_data = &vdso_data_store.data;
  30
  31 static int __init vdso_init(void)
  32 {
  33         unsigned int i;
  34
  35         vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
  36         vdso_pagelist =
  37                 kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
  38         if (unlikely(vdso_pagelist == NULL)) {
  39                 pr_err("vdso: pagelist allocation failed\n");
  40                 return -ENOMEM;
  41         }
  42
  43         for (i = 0; i < vdso_pages; i++) {
  44                 struct page *pg;
  45
  46                 pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
  47                 vdso_pagelist[i] = pg;
  48         }
  49         vdso_pagelist[i] = virt_to_page(vdso_data);
  50
  51         return 0;
  52 }
  53 arch_initcall(vdso_init);
  54
  55 int arch_setup_additional_pages(struct linux_binprm *bprm,
  56         int uses_interp)
  57 {
  58         struct mm_struct *mm = current->mm;
  59         unsigned long vdso_base, vdso_len;
  60         int ret;
  61
  62         vdso_len = (vdso_pages + 1) << PAGE_SHIFT;
  63
  64         mmap_write_lock(mm);
  65         vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
  66         if (IS_ERR_VALUE(vdso_base)) {
  67                 ret = vdso_base;
  68                 goto end;
  69         }
  70
  71         /*
  72          * Put vDSO base into mm struct. We need to do this before calling
  73          * install_special_mapping or the perf counter mmap tracking code
  74          * will fail to recognise it as a vDSO (since arch_vma_name fails).
  75          */
  76         mm->context.vdso = (void *)vdso_base;
  77
  78         ret =
  79            install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
  80                 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
  81                 vdso_pagelist);
  82
  83         if (unlikely(ret)) {
  84                 mm->context.vdso = NULL;
  85                 goto end;
  86         }
  87
  88         vdso_base += (vdso_pages << PAGE_SHIFT);
  89         ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
  90                 (VM_READ | VM_MAYREAD), &vdso_pagelist[vdso_pages]);
  91
  92         if (unlikely(ret))
  93                 mm->context.vdso = NULL;
  94 end:
  95         mmap_write_unlock(mm);
  96         return ret;
  97 }
  98
  99 const char *arch_vma_name(struct vm_area_struct *vma)
 100 {
 101         if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso))
 102                 return "[vdso]";
 103         if (vma->vm_mm && (vma->vm_start ==
 104                            (long)vma->vm_mm->context.vdso + PAGE_SIZE))
 105                 return "[vdso_data]";
 106         return NULL;
 107 }