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