1 /* 2 * VDSO implementation for AArch64 and vector page setup for AArch32. 3 * 4 * Copyright (C) 2012 ARM Limited 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program. If not, see <http://www.gnu.org/licenses/>. 17 * 18 * Author: Will Deacon <will.deacon@arm.com> 19 */ 20 21 #include <linux/cache.h> 22 #include <linux/clocksource.h> 23 #include <linux/elf.h> 24 #include <linux/err.h> 25 #include <linux/errno.h> 26 #include <linux/gfp.h> 27 #include <linux/kernel.h> 28 #include <linux/mm.h> 29 #include <linux/sched.h> 30 #include <linux/signal.h> 31 #include <linux/slab.h> 32 #include <linux/timekeeper_internal.h> 33 #include <linux/vmalloc.h> 34 35 #include <asm/cacheflush.h> 36 #include <asm/signal32.h> 37 #include <asm/vdso.h> 38 #include <asm/vdso_datapage.h> 39 40 extern char vdso_start[], vdso_end[]; 41 static unsigned long vdso_pages __ro_after_init; 42 43 /* 44 * The vDSO data page. 45 */ 46 static union { 47 struct vdso_data data; 48 u8 page[PAGE_SIZE]; 49 } vdso_data_store __page_aligned_data; 50 struct vdso_data *vdso_data = &vdso_data_store.data; 51 52 #ifdef CONFIG_COMPAT 53 /* 54 * Create and map the vectors page for AArch32 tasks. 55 */ 56 static struct page *vectors_page[1] __ro_after_init; 57 58 static int __init alloc_vectors_page(void) 59 { 60 extern char __kuser_helper_start[], __kuser_helper_end[]; 61 extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[]; 62 63 int kuser_sz = __kuser_helper_end - __kuser_helper_start; 64 int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start; 65 unsigned long vpage; 66 67 vpage = get_zeroed_page(GFP_ATOMIC); 68 69 if (!vpage) 70 return -ENOMEM; 71 72 /* kuser helpers */ 73 memcpy((void *)vpage + 0x1000 - kuser_sz, __kuser_helper_start, 74 kuser_sz); 75 76 /* sigreturn code */ 77 memcpy((void *)vpage + AARCH32_KERN_SIGRET_CODE_OFFSET, 78 __aarch32_sigret_code_start, sigret_sz); 79 80 flush_icache_range(vpage, vpage + PAGE_SIZE); 81 vectors_page[0] = virt_to_page(vpage); 82 83 return 0; 84 } 85 arch_initcall(alloc_vectors_page); 86 87 int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp) 88 { 89 struct mm_struct *mm = current->mm; 90 unsigned long addr = AARCH32_VECTORS_BASE; 91 static const struct vm_special_mapping spec = { 92 .name = "[vectors]", 93 .pages = vectors_page, 94 95 }; 96 void *ret; 97 98 if (down_write_killable(&mm->mmap_sem)) 99 return -EINTR; 100 current->mm->context.vdso = (void *)addr; 101 102 /* Map vectors page at the high address. */ 103 ret = _install_special_mapping(mm, addr, PAGE_SIZE, 104 VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC, 105 &spec); 106 107 up_write(&mm->mmap_sem); 108 109 return PTR_ERR_OR_ZERO(ret); 110 } 111 #endif /* CONFIG_COMPAT */ 112 113 static int vdso_mremap(const struct vm_special_mapping *sm, 114 struct vm_area_struct *new_vma) 115 { 116 unsigned long new_size = new_vma->vm_end - new_vma->vm_start; 117 unsigned long vdso_size = vdso_end - vdso_start; 118 119 if (vdso_size != new_size) 120 return -EINVAL; 121 122 current->mm->context.vdso = (void *)new_vma->vm_start; 123 124 return 0; 125 } 126 127 static struct vm_special_mapping vdso_spec[2] __ro_after_init = { 128 { 129 .name = "[vvar]", 130 }, 131 { 132 .name = "[vdso]", 133 .mremap = vdso_mremap, 134 }, 135 }; 136 137 static int __init vdso_init(void) 138 { 139 int i; 140 struct page **vdso_pagelist; 141 unsigned long pfn; 142 143 if (memcmp(vdso_start, "\177ELF", 4)) { 144 pr_err("vDSO is not a valid ELF object!\n"); 145 return -EINVAL; 146 } 147 148 vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT; 149 pr_info("vdso: %ld pages (%ld code @ %p, %ld data @ %p)\n", 150 vdso_pages + 1, vdso_pages, vdso_start, 1L, vdso_data); 151 152 /* Allocate the vDSO pagelist, plus a page for the data. */ 153 vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *), 154 GFP_KERNEL); 155 if (vdso_pagelist == NULL) 156 return -ENOMEM; 157 158 /* Grab the vDSO data page. */ 159 vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data)); 160 161 162 /* Grab the vDSO code pages. */ 163 pfn = sym_to_pfn(vdso_start); 164 165 for (i = 0; i < vdso_pages; i++) 166 vdso_pagelist[i + 1] = pfn_to_page(pfn + i); 167 168 vdso_spec[0].pages = &vdso_pagelist[0]; 169 vdso_spec[1].pages = &vdso_pagelist[1]; 170 171 return 0; 172 } 173 arch_initcall(vdso_init); 174 175 int arch_setup_additional_pages(struct linux_binprm *bprm, 176 int uses_interp) 177 { 178 struct mm_struct *mm = current->mm; 179 unsigned long vdso_base, vdso_text_len, vdso_mapping_len; 180 void *ret; 181 182 vdso_text_len = vdso_pages << PAGE_SHIFT; 183 /* Be sure to map the data page */ 184 vdso_mapping_len = vdso_text_len + PAGE_SIZE; 185 186 if (down_write_killable(&mm->mmap_sem)) 187 return -EINTR; 188 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 189 if (IS_ERR_VALUE(vdso_base)) { 190 ret = ERR_PTR(vdso_base); 191 goto up_fail; 192 } 193 ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE, 194 VM_READ|VM_MAYREAD, 195 &vdso_spec[0]); 196 if (IS_ERR(ret)) 197 goto up_fail; 198 199 vdso_base += PAGE_SIZE; 200 mm->context.vdso = (void *)vdso_base; 201 ret = _install_special_mapping(mm, vdso_base, vdso_text_len, 202 VM_READ|VM_EXEC| 203 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 204 &vdso_spec[1]); 205 if (IS_ERR(ret)) 206 goto up_fail; 207 208 209 up_write(&mm->mmap_sem); 210 return 0; 211 212 up_fail: 213 mm->context.vdso = NULL; 214 up_write(&mm->mmap_sem); 215 return PTR_ERR(ret); 216 } 217 218 /* 219 * Update the vDSO data page to keep in sync with kernel timekeeping. 220 */ 221 void update_vsyscall(struct timekeeper *tk) 222 { 223 u32 use_syscall = !tk->tkr_mono.clock->archdata.vdso_direct; 224 225 ++vdso_data->tb_seq_count; 226 smp_wmb(); 227 228 vdso_data->use_syscall = use_syscall; 229 vdso_data->xtime_coarse_sec = tk->xtime_sec; 230 vdso_data->xtime_coarse_nsec = tk->tkr_mono.xtime_nsec >> 231 tk->tkr_mono.shift; 232 vdso_data->wtm_clock_sec = tk->wall_to_monotonic.tv_sec; 233 vdso_data->wtm_clock_nsec = tk->wall_to_monotonic.tv_nsec; 234 235 if (!use_syscall) { 236 /* tkr_mono.cycle_last == tkr_raw.cycle_last */ 237 vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last; 238 vdso_data->raw_time_sec = tk->raw_sec; 239 vdso_data->raw_time_nsec = tk->tkr_raw.xtime_nsec; 240 vdso_data->xtime_clock_sec = tk->xtime_sec; 241 vdso_data->xtime_clock_nsec = tk->tkr_mono.xtime_nsec; 242 vdso_data->cs_mono_mult = tk->tkr_mono.mult; 243 vdso_data->cs_raw_mult = tk->tkr_raw.mult; 244 /* tkr_mono.shift == tkr_raw.shift */ 245 vdso_data->cs_shift = tk->tkr_mono.shift; 246 } 247 248 smp_wmb(); 249 ++vdso_data->tb_seq_count; 250 } 251 252 void update_vsyscall_tz(void) 253 { 254 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; 255 vdso_data->tz_dsttime = sys_tz.tz_dsttime; 256 } 257