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/kernel.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/mm.h> 28 #include <linux/sched.h> 29 #include <linux/signal.h> 30 #include <linux/slab.h> 31 #include <linux/timekeeper_internal.h> 32 #include <linux/vmalloc.h> 33 34 #include <asm/cacheflush.h> 35 #include <asm/signal32.h> 36 #include <asm/vdso.h> 37 #include <asm/vdso_datapage.h> 38 39 extern char vdso_start, vdso_end; 40 static unsigned long vdso_pages; 41 static struct page **vdso_pagelist; 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]; 57 58 static int 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 int ret; 92 93 down_write(&mm->mmap_sem); 94 current->mm->context.vdso = (void *)addr; 95 96 /* Map vectors page at the high address. */ 97 ret = install_special_mapping(mm, addr, PAGE_SIZE, 98 VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC, 99 vectors_page); 100 101 up_write(&mm->mmap_sem); 102 103 return ret; 104 } 105 #endif /* CONFIG_COMPAT */ 106 107 static int __init vdso_init(void) 108 { 109 struct page *pg; 110 char *vbase; 111 int i, ret = 0; 112 113 vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT; 114 pr_info("vdso: %ld pages (%ld code, %ld data) at base %p\n", 115 vdso_pages + 1, vdso_pages, 1L, &vdso_start); 116 117 /* Allocate the vDSO pagelist, plus a page for the data. */ 118 vdso_pagelist = kzalloc(sizeof(struct page *) * (vdso_pages + 1), 119 GFP_KERNEL); 120 if (vdso_pagelist == NULL) { 121 pr_err("Failed to allocate vDSO pagelist!\n"); 122 return -ENOMEM; 123 } 124 125 /* Grab the vDSO code pages. */ 126 for (i = 0; i < vdso_pages; i++) { 127 pg = virt_to_page(&vdso_start + i*PAGE_SIZE); 128 ClearPageReserved(pg); 129 get_page(pg); 130 vdso_pagelist[i] = pg; 131 } 132 133 /* Sanity check the shared object header. */ 134 vbase = vmap(vdso_pagelist, 1, 0, PAGE_KERNEL); 135 if (vbase == NULL) { 136 pr_err("Failed to map vDSO pagelist!\n"); 137 return -ENOMEM; 138 } else if (memcmp(vbase, "\177ELF", 4)) { 139 pr_err("vDSO is not a valid ELF object!\n"); 140 ret = -EINVAL; 141 goto unmap; 142 } 143 144 /* Grab the vDSO data page. */ 145 pg = virt_to_page(vdso_data); 146 get_page(pg); 147 vdso_pagelist[i] = pg; 148 149 unmap: 150 vunmap(vbase); 151 return ret; 152 } 153 arch_initcall(vdso_init); 154 155 int arch_setup_additional_pages(struct linux_binprm *bprm, 156 int uses_interp) 157 { 158 struct mm_struct *mm = current->mm; 159 unsigned long vdso_base, vdso_mapping_len; 160 int ret; 161 162 /* Be sure to map the data page */ 163 vdso_mapping_len = (vdso_pages + 1) << PAGE_SHIFT; 164 165 down_write(&mm->mmap_sem); 166 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 167 if (IS_ERR_VALUE(vdso_base)) { 168 ret = vdso_base; 169 goto up_fail; 170 } 171 mm->context.vdso = (void *)vdso_base; 172 173 ret = install_special_mapping(mm, vdso_base, vdso_mapping_len, 174 VM_READ|VM_EXEC| 175 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 176 vdso_pagelist); 177 if (ret) { 178 mm->context.vdso = NULL; 179 goto up_fail; 180 } 181 182 up_fail: 183 up_write(&mm->mmap_sem); 184 185 return ret; 186 } 187 188 const char *arch_vma_name(struct vm_area_struct *vma) 189 { 190 /* 191 * We can re-use the vdso pointer in mm_context_t for identifying 192 * the vectors page for compat applications. The vDSO will always 193 * sit above TASK_UNMAPPED_BASE and so we don't need to worry about 194 * it conflicting with the vectors base. 195 */ 196 if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) { 197 #ifdef CONFIG_COMPAT 198 if (vma->vm_start == AARCH32_VECTORS_BASE) 199 return "[vectors]"; 200 #endif 201 return "[vdso]"; 202 } 203 204 return NULL; 205 } 206 207 /* 208 * We define AT_SYSINFO_EHDR, so we need these function stubs to keep 209 * Linux happy. 210 */ 211 int in_gate_area_no_mm(unsigned long addr) 212 { 213 return 0; 214 } 215 216 int in_gate_area(struct mm_struct *mm, unsigned long addr) 217 { 218 return 0; 219 } 220 221 struct vm_area_struct *get_gate_vma(struct mm_struct *mm) 222 { 223 return NULL; 224 } 225 226 /* 227 * Update the vDSO data page to keep in sync with kernel timekeeping. 228 */ 229 void update_vsyscall(struct timekeeper *tk) 230 { 231 struct timespec xtime_coarse; 232 u32 use_syscall = strcmp(tk->clock->name, "arch_sys_counter"); 233 234 ++vdso_data->tb_seq_count; 235 smp_wmb(); 236 237 xtime_coarse = __current_kernel_time(); 238 vdso_data->use_syscall = use_syscall; 239 vdso_data->xtime_coarse_sec = xtime_coarse.tv_sec; 240 vdso_data->xtime_coarse_nsec = xtime_coarse.tv_nsec; 241 242 if (!use_syscall) { 243 vdso_data->cs_cycle_last = tk->clock->cycle_last; 244 vdso_data->xtime_clock_sec = tk->xtime_sec; 245 vdso_data->xtime_clock_nsec = tk->xtime_nsec; 246 vdso_data->cs_mult = tk->mult; 247 vdso_data->cs_shift = tk->shift; 248 vdso_data->wtm_clock_sec = tk->wall_to_monotonic.tv_sec; 249 vdso_data->wtm_clock_nsec = tk->wall_to_monotonic.tv_nsec; 250 } 251 252 smp_wmb(); 253 ++vdso_data->tb_seq_count; 254 } 255 256 void update_vsyscall_tz(void) 257 { 258 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; 259 vdso_data->tz_dsttime = sys_tz.tz_dsttime; 260 } 261