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 {
  29         u8 page[VDSO_DATA_SIZE];
  30         struct loongarch_vdso_data vdata;
  31 } loongarch_vdso_data __page_aligned_data;
  32
  33 static struct page *vdso_pages[] = { NULL };
  34 struct vdso_data *vdso_data = loongarch_vdso_data.vdata.data;
  35 struct vdso_pcpu_data *vdso_pdata = loongarch_vdso_data.vdata.pdata;
  36
  37 static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma)
  38 {
  39         current->mm->context.vdso = (void *)(new_vma->vm_start);
  40
  41         return 0;
  42 }
  43
  44 struct loongarch_vdso_info vdso_info = {
  45         .vdso = vdso_start,
  46         .size = PAGE_SIZE,
  47         .code_mapping = {
  48                 .name = "[vdso]",
  49                 .pages = vdso_pages,
  50                 .mremap = vdso_mremap,
  51         },
  52         .data_mapping = {
  53                 .name = "[vvar]",
  54         },
  55         .offset_sigreturn = vdso_offset_sigreturn,
  56 };
  57
  58 static int __init init_vdso(void)
  59 {
  60         unsigned long i, cpu, pfn;
  61
  62         BUG_ON(!PAGE_ALIGNED(vdso_info.vdso));
  63         BUG_ON(!PAGE_ALIGNED(vdso_info.size));
  64
  65         for_each_possible_cpu(cpu)
  66                 vdso_pdata[cpu].node = cpu_to_node(cpu);
  67
  68         pfn = __phys_to_pfn(__pa_symbol(vdso_info.vdso));
  69         for (i = 0; i < vdso_info.size / PAGE_SIZE; i++)
  70                 vdso_info.code_mapping.pages[i] = pfn_to_page(pfn + i);
  71
  72         return 0;
  73 }
  74 subsys_initcall(init_vdso);
  75
  76 static unsigned long vdso_base(void)
  77 {
  78         unsigned long base = STACK_TOP;
  79
  80         if (current->flags & PF_RANDOMIZE) {
  81                 base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1);
  82                 base = PAGE_ALIGN(base);
  83         }
  84
  85         return base;
  86 }
  87
  88 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
  89 {
  90         int ret;
  91         unsigned long vvar_size, size, data_addr, vdso_addr;
  92         struct mm_struct *mm = current->mm;
  93         struct vm_area_struct *vma;
  94         struct loongarch_vdso_info *info = current->thread.vdso;
  95
  96         if (mmap_write_lock_killable(mm))
  97                 return -EINTR;
  98
  99         /*
 100          * Determine total area size. This includes the VDSO data itself
 101          * and the data pages.
 102          */
 103         vvar_size = VDSO_DATA_SIZE;
 104         size = vvar_size + info->size;
 105
 106         data_addr = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
 107         if (IS_ERR_VALUE(data_addr)) {
 108                 ret = data_addr;
 109                 goto out;
 110         }
 111         vdso_addr = data_addr + VDSO_DATA_SIZE;
 112
 113         vma = _install_special_mapping(mm, data_addr, vvar_size,
 114                                        VM_READ | VM_MAYREAD,
 115                                        &info->data_mapping);
 116         if (IS_ERR(vma)) {
 117                 ret = PTR_ERR(vma);
 118                 goto out;
 119         }
 120
 121         /* Map VDSO data page. */
 122         ret = remap_pfn_range(vma, data_addr,
 123                               virt_to_phys(&loongarch_vdso_data) >> PAGE_SHIFT,
 124                               vvar_size, PAGE_READONLY);
 125         if (ret)
 126                 goto out;
 127
 128         /* Map VDSO code page. */
 129         vma = _install_special_mapping(mm, vdso_addr, info->size,
 130                                        VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
 131                                        &info->code_mapping);
 132         if (IS_ERR(vma)) {
 133                 ret = PTR_ERR(vma);
 134                 goto out;
 135         }
 136
 137         mm->context.vdso = (void *)vdso_addr;
 138         ret = 0;
 139
 140 out:
 141         mmap_write_unlock(mm);
 142         return ret;
 143 }