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 #include <asm/vdso.h> 16 #include <linux/vdso_datastore.h> 17 #include <vdso/datapage.h> 18 #include <vdso/vsyscall.h> 19 20 #define VVAR_SIZE (VDSO_NR_PAGES << PAGE_SHIFT) 21 22 struct __vdso_info { 23 const char *name; 24 const char *vdso_code_start; 25 const char *vdso_code_end; 26 unsigned long vdso_pages; 27 /* Code Mapping */ 28 struct vm_special_mapping *cm; 29 }; 30 31 static struct __vdso_info vdso_info; 32 #ifdef CONFIG_COMPAT 33 static struct __vdso_info compat_vdso_info; 34 #endif 35 36 static int vdso_mremap(const struct vm_special_mapping *sm, 37 struct vm_area_struct *new_vma) 38 { 39 current->mm->context.vdso = (void *)new_vma->vm_start; 40 41 return 0; 42 } 43 44 static void __init __vdso_init(struct __vdso_info *vdso_info) 45 { 46 unsigned int i; 47 struct page **vdso_pagelist; 48 unsigned long pfn; 49 50 if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4)) 51 panic("vDSO is not a valid ELF object!\n"); 52 53 vdso_info->vdso_pages = ( 54 vdso_info->vdso_code_end - 55 vdso_info->vdso_code_start) >> 56 PAGE_SHIFT; 57 58 vdso_pagelist = kzalloc_objs(struct page *, vdso_info->vdso_pages, 59 GFP_KERNEL); 60 if (vdso_pagelist == NULL) 61 panic("vDSO kcalloc failed!\n"); 62 63 /* Grab the vDSO code pages. */ 64 pfn = sym_to_pfn(vdso_info->vdso_code_start); 65 66 for (i = 0; i < vdso_info->vdso_pages; i++) 67 vdso_pagelist[i] = pfn_to_page(pfn + i); 68 69 vdso_info->cm->pages = vdso_pagelist; 70 } 71 72 static struct vm_special_mapping rv_vdso_map __ro_after_init = { 73 .name = "[vdso]", 74 .mremap = vdso_mremap, 75 }; 76 77 static struct __vdso_info vdso_info __ro_after_init = { 78 .name = "vdso", 79 .vdso_code_start = vdso_start, 80 .vdso_code_end = vdso_end, 81 .cm = &rv_vdso_map, 82 }; 83 84 #ifdef CONFIG_COMPAT 85 static struct vm_special_mapping rv_compat_vdso_map __ro_after_init = { 86 .name = "[vdso]", 87 .mremap = vdso_mremap, 88 }; 89 90 static struct __vdso_info compat_vdso_info __ro_after_init = { 91 .name = "compat_vdso", 92 .vdso_code_start = compat_vdso_start, 93 .vdso_code_end = compat_vdso_end, 94 .cm = &rv_compat_vdso_map, 95 }; 96 #endif 97 98 static int __init vdso_init(void) 99 { 100 /* Hart implements zimop, expose cfi compiled vdso */ 101 if (IS_ENABLED(CONFIG_RISCV_USER_CFI) && 102 riscv_has_extension_unlikely(RISCV_ISA_EXT_ZIMOP)) { 103 vdso_info.vdso_code_start = vdso_cfi_start; 104 vdso_info.vdso_code_end = vdso_cfi_end; 105 } 106 107 __vdso_init(&vdso_info); 108 #ifdef CONFIG_COMPAT 109 __vdso_init(&compat_vdso_info); 110 #endif 111 112 return 0; 113 } 114 arch_initcall(vdso_init); 115 116 static int __setup_additional_pages(struct mm_struct *mm, 117 struct linux_binprm *bprm, 118 int uses_interp, 119 struct __vdso_info *vdso_info) 120 { 121 unsigned long vdso_base, vdso_text_len, vdso_mapping_len; 122 void *ret; 123 124 BUILD_BUG_ON(VDSO_NR_PAGES != __VDSO_PAGES); 125 126 vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT; 127 /* Be sure to map the data page */ 128 vdso_mapping_len = vdso_text_len + VVAR_SIZE; 129 130 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 131 if (IS_ERR_VALUE(vdso_base)) { 132 ret = ERR_PTR(vdso_base); 133 goto up_fail; 134 } 135 136 ret = vdso_install_vvar_mapping(mm, vdso_base); 137 if (IS_ERR(ret)) 138 goto up_fail; 139 140 vdso_base += VVAR_SIZE; 141 mm->context.vdso = (void *)vdso_base; 142 143 ret = 144 _install_special_mapping(mm, vdso_base, vdso_text_len, 145 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC | VM_SEALED_SYSMAP), 146 vdso_info->cm); 147 148 if (IS_ERR(ret)) 149 goto up_fail; 150 151 return 0; 152 153 up_fail: 154 mm->context.vdso = NULL; 155 return PTR_ERR(ret); 156 } 157 158 #ifdef CONFIG_COMPAT 159 int compat_arch_setup_additional_pages(struct linux_binprm *bprm, 160 int uses_interp) 161 { 162 struct mm_struct *mm = current->mm; 163 int ret; 164 165 if (mmap_write_lock_killable(mm)) 166 return -EINTR; 167 168 ret = __setup_additional_pages(mm, bprm, uses_interp, 169 &compat_vdso_info); 170 mmap_write_unlock(mm); 171 172 return ret; 173 } 174 #endif 175 176 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 177 { 178 struct mm_struct *mm = current->mm; 179 int ret; 180 181 if (mmap_write_lock_killable(mm)) 182 return -EINTR; 183 184 ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info); 185 mmap_write_unlock(mm); 186 187 return ret; 188 } 189