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 int kuser_sz = __kuser_helper_end - __kuser_helper_start; 62 unsigned long vpage; 63 64 vpage = get_zeroed_page(GFP_ATOMIC); 65 66 if (!vpage) 67 return -ENOMEM; 68 69 /* kuser helpers */ 70 memcpy((void *)vpage + 0x1000 - kuser_sz, __kuser_helper_start, 71 kuser_sz); 72 73 /* sigreturn code */ 74 memcpy((void *)vpage + AARCH32_KERN_SIGRET_CODE_OFFSET, 75 aarch32_sigret_code, sizeof(aarch32_sigret_code)); 76 77 flush_icache_range(vpage, vpage + PAGE_SIZE); 78 vectors_page[0] = virt_to_page(vpage); 79 80 return 0; 81 } 82 arch_initcall(alloc_vectors_page); 83 84 int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp) 85 { 86 struct mm_struct *mm = current->mm; 87 unsigned long addr = AARCH32_VECTORS_BASE; 88 int ret; 89 90 down_write(&mm->mmap_sem); 91 current->mm->context.vdso = (void *)addr; 92 93 /* Map vectors page at the high address. */ 94 ret = install_special_mapping(mm, addr, PAGE_SIZE, 95 VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC, 96 vectors_page); 97 98 up_write(&mm->mmap_sem); 99 100 return ret; 101 } 102 #endif /* CONFIG_COMPAT */ 103 104 static int __init vdso_init(void) 105 { 106 struct page *pg; 107 char *vbase; 108 int i, ret = 0; 109 110 vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT; 111 pr_info("vdso: %ld pages (%ld code, %ld data) at base %p\n", 112 vdso_pages + 1, vdso_pages, 1L, &vdso_start); 113 114 /* Allocate the vDSO pagelist, plus a page for the data. */ 115 vdso_pagelist = kzalloc(sizeof(struct page *) * (vdso_pages + 1), 116 GFP_KERNEL); 117 if (vdso_pagelist == NULL) { 118 pr_err("Failed to allocate vDSO pagelist!\n"); 119 return -ENOMEM; 120 } 121 122 /* Grab the vDSO code pages. */ 123 for (i = 0; i < vdso_pages; i++) { 124 pg = virt_to_page(&vdso_start + i*PAGE_SIZE); 125 ClearPageReserved(pg); 126 get_page(pg); 127 vdso_pagelist[i] = pg; 128 } 129 130 /* Sanity check the shared object header. */ 131 vbase = vmap(vdso_pagelist, 1, 0, PAGE_KERNEL); 132 if (vbase == NULL) { 133 pr_err("Failed to map vDSO pagelist!\n"); 134 return -ENOMEM; 135 } else if (memcmp(vbase, "\177ELF", 4)) { 136 pr_err("vDSO is not a valid ELF object!\n"); 137 ret = -EINVAL; 138 goto unmap; 139 } 140 141 /* Grab the vDSO data page. */ 142 pg = virt_to_page(vdso_data); 143 get_page(pg); 144 vdso_pagelist[i] = pg; 145 146 unmap: 147 vunmap(vbase); 148 return ret; 149 } 150 arch_initcall(vdso_init); 151 152 int arch_setup_additional_pages(struct linux_binprm *bprm, 153 int uses_interp) 154 { 155 struct mm_struct *mm = current->mm; 156 unsigned long vdso_base, vdso_mapping_len; 157 int ret; 158 159 /* Be sure to map the data page */ 160 vdso_mapping_len = (vdso_pages + 1) << PAGE_SHIFT; 161 162 down_write(&mm->mmap_sem); 163 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 164 if (IS_ERR_VALUE(vdso_base)) { 165 ret = vdso_base; 166 goto up_fail; 167 } 168 mm->context.vdso = (void *)vdso_base; 169 170 ret = install_special_mapping(mm, vdso_base, vdso_mapping_len, 171 VM_READ|VM_EXEC| 172 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 173 vdso_pagelist); 174 if (ret) { 175 mm->context.vdso = NULL; 176 goto up_fail; 177 } 178 179 up_fail: 180 up_write(&mm->mmap_sem); 181 182 return ret; 183 } 184 185 const char *arch_vma_name(struct vm_area_struct *vma) 186 { 187 /* 188 * We can re-use the vdso pointer in mm_context_t for identifying 189 * the vectors page for compat applications. The vDSO will always 190 * sit above TASK_UNMAPPED_BASE and so we don't need to worry about 191 * it conflicting with the vectors base. 192 */ 193 if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) { 194 #ifdef CONFIG_COMPAT 195 if (vma->vm_start == AARCH32_VECTORS_BASE) 196 return "[vectors]"; 197 #endif 198 return "[vdso]"; 199 } 200 201 return NULL; 202 } 203 204 /* 205 * We define AT_SYSINFO_EHDR, so we need these function stubs to keep 206 * Linux happy. 207 */ 208 int in_gate_area_no_mm(unsigned long addr) 209 { 210 return 0; 211 } 212 213 int in_gate_area(struct mm_struct *mm, unsigned long addr) 214 { 215 return 0; 216 } 217 218 struct vm_area_struct *get_gate_vma(struct mm_struct *mm) 219 { 220 return NULL; 221 } 222 223 /* 224 * Update the vDSO data page to keep in sync with kernel timekeeping. 225 */ 226 void update_vsyscall(struct timekeeper *tk) 227 { 228 struct timespec xtime_coarse; 229 u32 use_syscall = strcmp(tk->clock->name, "arch_sys_counter"); 230 231 ++vdso_data->tb_seq_count; 232 smp_wmb(); 233 234 xtime_coarse = __current_kernel_time(); 235 vdso_data->use_syscall = use_syscall; 236 vdso_data->xtime_coarse_sec = xtime_coarse.tv_sec; 237 vdso_data->xtime_coarse_nsec = xtime_coarse.tv_nsec; 238 239 if (!use_syscall) { 240 vdso_data->cs_cycle_last = tk->clock->cycle_last; 241 vdso_data->xtime_clock_sec = tk->xtime_sec; 242 vdso_data->xtime_clock_nsec = tk->xtime_nsec; 243 vdso_data->cs_mult = tk->mult; 244 vdso_data->cs_shift = tk->shift; 245 vdso_data->wtm_clock_sec = tk->wall_to_monotonic.tv_sec; 246 vdso_data->wtm_clock_nsec = tk->wall_to_monotonic.tv_nsec; 247 } 248 249 smp_wmb(); 250 ++vdso_data->tb_seq_count; 251 } 252 253 void update_vsyscall_tz(void) 254 { 255 ++vdso_data->tb_seq_count; 256 smp_wmb(); 257 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; 258 vdso_data->tz_dsttime = sys_tz.tz_dsttime; 259 smp_wmb(); 260 ++vdso_data->tb_seq_count; 261 } 262