LXR linux/arch/riscv/kernel/vdso.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
   4 *                    <benh@kernel.crashing.org>
   5 * Copyright (C) 2012 ARM Limited
   6 * Copyright (C) 2015 Regents of the University of California
   7 */
   8
   9#include <linux/elf.h>
  10#include <linux/mm.h>
  11#include <linux/slab.h>
  12#include <linux/binfmts.h>
  13#include <linux/err.h>
  14#include <asm/page.h>
  15#ifdef GENERIC_TIME_VSYSCALL
  16#include <vdso/datapage.h>
  17#else
  18#include <asm/vdso.h>
  19#endif
  20
  21extern char vdso_start[], vdso_end[];
  22
  23static unsigned int vdso_pages;
  24static struct page **vdso_pagelist;
  25
  26/*
  27 * The vDSO data page.
  28 */
  29static union {
  30        struct vdso_data        data;
  31        u8                      page[PAGE_SIZE];
  32} vdso_data_store __page_aligned_data;
  33struct vdso_data *vdso_data = &vdso_data_store.data;
  34
  35static int __init vdso_init(void)
  36{
  37        unsigned int i;
  38
  39        vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
  40        vdso_pagelist =
  41                kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
  42        if (unlikely(vdso_pagelist == NULL)) {
  43                pr_err("vdso: pagelist allocation failed\n");
  44                return -ENOMEM;
  45        }
  46
  47        for (i = 0; i < vdso_pages; i++) {
  48                struct page *pg;
  49
  50                pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
  51                vdso_pagelist[i] = pg;
  52        }
  53        vdso_pagelist[i] = virt_to_page(vdso_data);
  54
  55        return 0;
  56}
  57arch_initcall(vdso_init);
  58
  59int arch_setup_additional_pages(struct linux_binprm *bprm,
  60        int uses_interp)
  61{
  62        struct mm_struct *mm = current->mm;
  63        unsigned long vdso_base, vdso_len;
  64        int ret;
  65
  66        vdso_len = (vdso_pages + 1) << PAGE_SHIFT;
  67
  68        mmap_write_lock(mm);
  69        vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
  70        if (IS_ERR_VALUE(vdso_base)) {
  71                ret = vdso_base;
  72                goto end;
  73        }
  74
  75        /*
  76         * Put vDSO base into mm struct. We need to do this before calling
  77         * install_special_mapping or the perf counter mmap tracking code
  78         * will fail to recognise it as a vDSO (since arch_vma_name fails).
  79         */
  80        mm->context.vdso = (void *)vdso_base;
  81
  82        ret =
  83           install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
  84                (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
  85                vdso_pagelist);
  86
  87        if (unlikely(ret)) {
  88                mm->context.vdso = NULL;
  89                goto end;
  90        }
  91
  92        vdso_base += (vdso_pages << PAGE_SHIFT);
  93        ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
  94                (VM_READ | VM_MAYREAD), &vdso_pagelist[vdso_pages]);
  95
  96        if (unlikely(ret))
  97                mm->context.vdso = NULL;
  98end:
  99        mmap_write_unlock(mm);
 100        return ret;
 101}
 102
 103const 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}
 112