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