arch/loongarch/kernel/vdso.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Author: Huacai Chen <chenhuacai@loongson.cn>
   4  * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
   5  */
   6
   7 #include <linux/binfmts.h>
   8 #include <linux/elf.h>
   9 #include <linux/err.h>
  10 #include <linux/init.h>
  11 #include <linux/ioport.h>
  12 #include <linux/kernel.h>
  13 #include <linux/mm.h>
  14 #include <linux/random.h>
  15 #include <linux/sched.h>
  16 #include <linux/slab.h>
  17 #include <linux/timekeeper_internal.h>
  18
  19 #include <asm/page.h>
  20 #include <asm/vdso.h>
  21 #include <vdso/helpers.h>
  22 #include <vdso/vsyscall.h>
  23 #include <generated/vdso-offsets.h>
  24
  25 extern char vdso_start[], vdso_end[];
  26
  27 /* Kernel-provided data used by the VDSO. */
  28 static union loongarch_vdso_data {
  29         u8 page[PAGE_SIZE];
  30         struct vdso_data data[CS_BASES];
  31 } loongarch_vdso_data __page_aligned_data;
  32 struct vdso_data *vdso_data = loongarch_vdso_data.data;
  33 static struct page *vdso_pages[] = { NULL };
  34
  35 static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
  36 {
  37         current->mm->context.vdso = (void *)(new_vma->vm_start);
  38
  39         return 0;
  40 }
  41
  42 struct loongarch_vdso_info vdso_info = {
  43         .vdso = vdso_start,
  44         .size = PAGE_SIZE,
  45         .code_mapping = {
  46                 .name = "[vdso]",
  47                 .pages = vdso_pages,
  48                 .mremap = vdso_mremap,
  49         },
  50         .data_mapping = {
  51                 .name = "[vvar]",
  52         },
  53         .offset_sigreturn = vdso_offset_sigreturn,
  54 };
  55
  56 static int __init init_vdso(void)
  57 {
  58         unsigned long i, pfn;
  59
  60         BUG_ON(!PAGE_ALIGNED(vdso_info.vdso));
  61         BUG_ON(!PAGE_ALIGNED(vdso_info.size));
  62
  63         pfn = __phys_to_pfn(__pa_symbol(vdso_info.vdso));
  64         for (i = 0; i < vdso_info.size / PAGE_SIZE; i++)
  65                 vdso_info.code_mapping.pages[i] = pfn_to_page(pfn + i);
  66
  67         return 0;
  68 }
  69 subsys_initcall(init_vdso);
  70
  71 static unsigned long vdso_base(void)
  72 {
  73         unsigned long base = STACK_TOP;
  74
  75         if (current->flags & PF_RANDOMIZE) {
  76                 base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1);
  77                 base = PAGE_ALIGN(base);
  78         }
  79
  80         return base;
  81 }
  82
  83 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
  84 {
  85         int ret;
  86         unsigned long vvar_size, size, data_addr, vdso_addr;
  87         struct mm_struct *mm = current->mm;
  88         struct vm_area_struct *vma;
  89         struct loongarch_vdso_info *info = current->thread.vdso;
  90
  91         if (mmap_write_lock_killable(mm))
  92                 return -EINTR;
  93
  94         /*
  95          * Determine total area size. This includes the VDSO data itself
  96          * and the data page.
  97          */
  98         vvar_size = PAGE_SIZE;
  99         size = vvar_size + info->size;
 100
 101         data_addr = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
 102         if (IS_ERR_VALUE(data_addr)) {
 103                 ret = data_addr;
 104                 goto out;
 105         }
 106         vdso_addr = data_addr + PAGE_SIZE;
 107
 108         vma = _install_special_mapping(mm, data_addr, vvar_size,
 109                                        VM_READ | VM_MAYREAD,
 110                                        &info->data_mapping);
 111         if (IS_ERR(vma)) {
 112                 ret = PTR_ERR(vma);
 113                 goto out;
 114         }
 115
 116         /* Map VDSO data page. */
 117         ret = remap_pfn_range(vma, data_addr,
 118                               virt_to_phys(vdso_data) >> PAGE_SHIFT,
 119                               PAGE_SIZE, PAGE_READONLY);
 120         if (ret)
 121                 goto out;
 122
 123         /* Map VDSO code page. */
 124         vma = _install_special_mapping(mm, vdso_addr, info->size,
 125                                        VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
 126                                        &info->code_mapping);
 127         if (IS_ERR(vma)) {
 128                 ret = PTR_ERR(vma);
 129                 goto out;
 130         }
 131
 132         mm->context.vdso = (void *)vdso_addr;
 133         ret = 0;
 134
 135 out:
 136         mmap_write_unlock(mm);
 137         return ret;
 138 }