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/time_namespace.h> 18 #include <linux/timekeeper_internal.h> 19 20 #include <asm/page.h> 21 #include <asm/vdso.h> 22 #include <vdso/helpers.h> 23 #include <vdso/vsyscall.h> 24 #include <generated/vdso-offsets.h> 25 26 extern char vdso_start[], vdso_end[]; 27 28 /* Kernel-provided data used by the VDSO. */ 29 static union { 30 u8 page[PAGE_SIZE]; 31 struct vdso_data data[CS_BASES]; 32 } generic_vdso_data __page_aligned_data; 33 34 static union { 35 u8 page[LOONGARCH_VDSO_DATA_SIZE]; 36 struct loongarch_vdso_data vdata; 37 } loongarch_vdso_data __page_aligned_data; 38 39 static struct page *vdso_pages[] = { NULL }; 40 struct vdso_data *vdso_data = generic_vdso_data.data; 41 struct vdso_pcpu_data *vdso_pdata = loongarch_vdso_data.vdata.pdata; 42 43 static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma) 44 { 45 current->mm->context.vdso = (void *)(new_vma->vm_start); 46 47 return 0; 48 } 49 50 static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, 51 struct vm_area_struct *vma, struct vm_fault *vmf) 52 { 53 unsigned long pfn; 54 struct page *timens_page = find_timens_vvar_page(vma); 55 56 switch (vmf->pgoff) { 57 case VVAR_GENERIC_PAGE_OFFSET: 58 if (!timens_page) 59 pfn = sym_to_pfn(vdso_data); 60 else 61 pfn = page_to_pfn(timens_page); 62 break; 63 #ifdef CONFIG_TIME_NS 64 case VVAR_TIMENS_PAGE_OFFSET: 65 /* 66 * If a task belongs to a time namespace then a namespace specific 67 * VVAR is mapped with the VVAR_GENERIC_PAGE_OFFSET and the real 68 * VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET offset. 69 * See also the comment near timens_setup_vdso_data(). 70 */ 71 if (!timens_page) 72 return VM_FAULT_SIGBUS; 73 else 74 pfn = sym_to_pfn(vdso_data); 75 break; 76 #endif /* CONFIG_TIME_NS */ 77 case VVAR_LOONGARCH_PAGES_START ... VVAR_LOONGARCH_PAGES_END: 78 pfn = sym_to_pfn(&loongarch_vdso_data) + vmf->pgoff - VVAR_LOONGARCH_PAGES_START; 79 break; 80 default: 81 return VM_FAULT_SIGBUS; 82 } 83 84 return vmf_insert_pfn(vma, vmf->address, pfn); 85 } 86 87 struct loongarch_vdso_info vdso_info = { 88 .vdso = vdso_start, 89 .size = PAGE_SIZE, 90 .code_mapping = { 91 .name = "[vdso]", 92 .pages = vdso_pages, 93 .mremap = vdso_mremap, 94 }, 95 .data_mapping = { 96 .name = "[vvar]", 97 .fault = vvar_fault, 98 }, 99 .offset_sigreturn = vdso_offset_sigreturn, 100 }; 101 102 static int __init init_vdso(void) 103 { 104 unsigned long i, cpu, pfn; 105 106 BUG_ON(!PAGE_ALIGNED(vdso_info.vdso)); 107 BUG_ON(!PAGE_ALIGNED(vdso_info.size)); 108 109 for_each_possible_cpu(cpu) 110 vdso_pdata[cpu].node = cpu_to_node(cpu); 111 112 pfn = __phys_to_pfn(__pa_symbol(vdso_info.vdso)); 113 for (i = 0; i < vdso_info.size / PAGE_SIZE; i++) 114 vdso_info.code_mapping.pages[i] = pfn_to_page(pfn + i); 115 116 return 0; 117 } 118 subsys_initcall(init_vdso); 119 120 #ifdef CONFIG_TIME_NS 121 struct vdso_data *arch_get_vdso_data(void *vvar_page) 122 { 123 return (struct vdso_data *)(vvar_page); 124 } 125 126 /* 127 * The vvar mapping contains data for a specific time namespace, so when a 128 * task changes namespace we must unmap its vvar data for the old namespace. 129 * Subsequent faults will map in data for the new namespace. 130 * 131 * For more details see timens_setup_vdso_data(). 132 */ 133 int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) 134 { 135 struct mm_struct *mm = task->mm; 136 struct vm_area_struct *vma; 137 138 VMA_ITERATOR(vmi, mm, 0); 139 140 mmap_read_lock(mm); 141 for_each_vma(vmi, vma) { 142 if (vma_is_special_mapping(vma, &vdso_info.data_mapping)) 143 zap_vma_pages(vma); 144 } 145 mmap_read_unlock(mm); 146 147 return 0; 148 } 149 #endif 150 151 static unsigned long vdso_base(void) 152 { 153 unsigned long base = STACK_TOP; 154 155 if (current->flags & PF_RANDOMIZE) { 156 base += get_random_u32_below(VDSO_RANDOMIZE_SIZE); 157 base = PAGE_ALIGN(base); 158 } 159 160 return base; 161 } 162 163 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 164 { 165 int ret; 166 unsigned long size, data_addr, vdso_addr; 167 struct mm_struct *mm = current->mm; 168 struct vm_area_struct *vma; 169 struct loongarch_vdso_info *info = current->thread.vdso; 170 171 if (mmap_write_lock_killable(mm)) 172 return -EINTR; 173 174 /* 175 * Determine total area size. This includes the VDSO data itself 176 * and the data pages. 177 */ 178 size = VVAR_SIZE + info->size; 179 180 data_addr = get_unmapped_area(NULL, vdso_base(), size, 0, 0); 181 if (IS_ERR_VALUE(data_addr)) { 182 ret = data_addr; 183 goto out; 184 } 185 186 vma = _install_special_mapping(mm, data_addr, VVAR_SIZE, 187 VM_READ | VM_MAYREAD | VM_PFNMAP, 188 &info->data_mapping); 189 if (IS_ERR(vma)) { 190 ret = PTR_ERR(vma); 191 goto out; 192 } 193 194 vdso_addr = data_addr + VVAR_SIZE; 195 vma = _install_special_mapping(mm, vdso_addr, info->size, 196 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, 197 &info->code_mapping); 198 if (IS_ERR(vma)) { 199 ret = PTR_ERR(vma); 200 goto out; 201 } 202 203 mm->context.vdso = (void *)vdso_addr; 204 ret = 0; 205 206 out: 207 mmap_write_unlock(mm); 208 return ret; 209 } 210