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 if (vdso_pagelist == NULL) 60 panic("vDSO kcalloc failed!\n"); 61 62 /* Grab the vDSO code pages. */ 63 pfn = sym_to_pfn(vdso_info->vdso_code_start); 64 65 for (i = 0; i < vdso_info->vdso_pages; i++) 66 vdso_pagelist[i] = pfn_to_page(pfn + i); 67 68 vdso_info->cm->pages = vdso_pagelist; 69 } 70 71 static struct vm_special_mapping rv_vdso_map __ro_after_init = { 72 .name = "[vdso]", 73 .mremap = vdso_mremap, 74 }; 75 76 static struct __vdso_info vdso_info __ro_after_init = { 77 .name = "vdso", 78 .vdso_code_start = vdso_start, 79 .vdso_code_end = vdso_end, 80 .cm = &rv_vdso_map, 81 }; 82 83 #ifdef CONFIG_COMPAT 84 static struct vm_special_mapping rv_compat_vdso_map __ro_after_init = { 85 .name = "[vdso]", 86 .mremap = vdso_mremap, 87 }; 88 89 static struct __vdso_info compat_vdso_info __ro_after_init = { 90 .name = "compat_vdso", 91 .vdso_code_start = compat_vdso_start, 92 .vdso_code_end = compat_vdso_end, 93 .cm = &rv_compat_vdso_map, 94 }; 95 #endif 96 97 static int __init vdso_init(void) 98 { 99 /* Hart implements zimop, expose cfi compiled vdso */ 100 if (IS_ENABLED(CONFIG_RISCV_USER_CFI) && 101 riscv_has_extension_unlikely(RISCV_ISA_EXT_ZIMOP)) { 102 vdso_info.vdso_code_start = vdso_cfi_start; 103 vdso_info.vdso_code_end = vdso_cfi_end; 104 } 105 106 __vdso_init(&vdso_info); 107 #ifdef CONFIG_COMPAT 108 __vdso_init(&compat_vdso_info); 109 #endif 110 111 return 0; 112 } 113 arch_initcall(vdso_init); 114 115 static int __setup_additional_pages(struct mm_struct *mm, 116 struct linux_binprm *bprm, 117 int uses_interp, 118 struct __vdso_info *vdso_info) 119 { 120 unsigned long vdso_base, vdso_text_len, vdso_mapping_len; 121 void *ret; 122 123 BUILD_BUG_ON(VDSO_NR_PAGES != __VDSO_PAGES); 124 125 vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT; 126 /* Be sure to map the data page */ 127 vdso_mapping_len = vdso_text_len + VVAR_SIZE; 128 129 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 130 if (IS_ERR_VALUE(vdso_base)) { 131 ret = ERR_PTR(vdso_base); 132 goto up_fail; 133 } 134 135 ret = vdso_install_vvar_mapping(mm, vdso_base); 136 if (IS_ERR(ret)) 137 goto up_fail; 138 139 vdso_base += VVAR_SIZE; 140 mm->context.vdso = (void *)vdso_base; 141 142 ret = 143 _install_special_mapping(mm, vdso_base, vdso_text_len, 144 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC | VM_SEALED_SYSMAP), 145 vdso_info->cm); 146 147 if (IS_ERR(ret)) 148 goto up_fail; 149 150 return 0; 151 152 up_fail: 153 mm->context.vdso = NULL; 154 return PTR_ERR(ret); 155 } 156 157 #ifdef CONFIG_COMPAT 158 int compat_arch_setup_additional_pages(struct linux_binprm *bprm, 159 int uses_interp) 160 { 161 struct mm_struct *mm = current->mm; 162 int ret; 163 164 if (mmap_write_lock_killable(mm)) 165 return -EINTR; 166 167 ret = __setup_additional_pages(mm, bprm, uses_interp, 168 &compat_vdso_info); 169 mmap_write_unlock(mm); 170 171 return ret; 172 } 173 #endif 174 175 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 176 { 177 struct mm_struct *mm = current->mm; 178 int ret; 179 180 if (mmap_write_lock_killable(mm)) 181 return -EINTR; 182 183 ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info); 184 mmap_write_unlock(mm); 185 186 return ret; 187 } 188