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/vmalloc.h> 32 33 #include <asm/cacheflush.h> 34 #include <asm/signal32.h> 35 #include <asm/vdso.h> 36 #include <asm/vdso_datapage.h> 37 38 extern char vdso_start, vdso_end; 39 static unsigned long vdso_pages; 40 static struct page **vdso_pagelist; 41 42 /* 43 * The vDSO data page. 44 */ 45 static union { 46 struct vdso_data data; 47 u8 page[PAGE_SIZE]; 48 } vdso_data_store __page_aligned_data; 49 struct vdso_data *vdso_data = &vdso_data_store.data; 50 51 #ifdef CONFIG_COMPAT 52 /* 53 * Create and map the vectors page for AArch32 tasks. 54 */ 55 static struct page *vectors_page[1]; 56 57 static int alloc_vectors_page(void) 58 { 59 extern char __kuser_helper_start[], __kuser_helper_end[]; 60 int kuser_sz = __kuser_helper_end - __kuser_helper_start; 61 unsigned long vpage; 62 63 vpage = get_zeroed_page(GFP_ATOMIC); 64 65 if (!vpage) 66 return -ENOMEM; 67 68 /* kuser helpers */ 69 memcpy((void *)vpage + 0x1000 - kuser_sz, __kuser_helper_start, 70 kuser_sz); 71 72 /* sigreturn code */ 73 memcpy((void *)vpage + AARCH32_KERN_SIGRET_CODE_OFFSET, 74 aarch32_sigret_code, sizeof(aarch32_sigret_code)); 75 76 flush_icache_range(vpage, vpage + PAGE_SIZE); 77 vectors_page[0] = virt_to_page(vpage); 78 79 return 0; 80 } 81 arch_initcall(alloc_vectors_page); 82 83 int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp) 84 { 85 struct mm_struct *mm = current->mm; 86 unsigned long addr = AARCH32_VECTORS_BASE; 87 int ret; 88 89 down_write(&mm->mmap_sem); 90 current->mm->context.vdso = (void *)addr; 91 92 /* Map vectors page at the high address. */ 93 ret = install_special_mapping(mm, addr, PAGE_SIZE, 94 VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC, 95 vectors_page); 96 97 up_write(&mm->mmap_sem); 98 99 return ret; 100 } 101 #endif /* CONFIG_COMPAT */ 102 103 static int __init vdso_init(void) 104 { 105 struct page *pg; 106 char *vbase; 107 int i, ret = 0; 108 109 vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT; 110 pr_info("vdso: %ld pages (%ld code, %ld data) at base %p\n", 111 vdso_pages + 1, vdso_pages, 1L, &vdso_start); 112 113 /* Allocate the vDSO pagelist, plus a page for the data. */ 114 vdso_pagelist = kzalloc(sizeof(struct page *) * (vdso_pages + 1), 115 GFP_KERNEL); 116 if (vdso_pagelist == NULL) { 117 pr_err("Failed to allocate vDSO pagelist!\n"); 118 return -ENOMEM; 119 } 120 121 /* Grab the vDSO code pages. */ 122 for (i = 0; i < vdso_pages; i++) { 123 pg = virt_to_page(&vdso_start + i*PAGE_SIZE); 124 ClearPageReserved(pg); 125 get_page(pg); 126 vdso_pagelist[i] = pg; 127 } 128 129 /* Sanity check the shared object header. */ 130 vbase = vmap(vdso_pagelist, 1, 0, PAGE_KERNEL); 131 if (vbase == NULL) { 132 pr_err("Failed to map vDSO pagelist!\n"); 133 return -ENOMEM; 134 } else if (memcmp(vbase, "\177ELF", 4)) { 135 pr_err("vDSO is not a valid ELF object!\n"); 136 ret = -EINVAL; 137 goto unmap; 138 } 139 140 /* Grab the vDSO data page. */ 141 pg = virt_to_page(vdso_data); 142 get_page(pg); 143 vdso_pagelist[i] = pg; 144 145 unmap: 146 vunmap(vbase); 147 return ret; 148 } 149 arch_initcall(vdso_init); 150 151 int arch_setup_additional_pages(struct linux_binprm *bprm, 152 int uses_interp) 153 { 154 struct mm_struct *mm = current->mm; 155 unsigned long vdso_base, vdso_mapping_len; 156 int ret; 157 158 /* Be sure to map the data page */ 159 vdso_mapping_len = (vdso_pages + 1) << PAGE_SHIFT; 160 161 down_write(&mm->mmap_sem); 162 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 163 if (IS_ERR_VALUE(vdso_base)) { 164 ret = vdso_base; 165 goto up_fail; 166 } 167 mm->context.vdso = (void *)vdso_base; 168 169 ret = install_special_mapping(mm, vdso_base, vdso_mapping_len, 170 VM_READ|VM_EXEC| 171 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 172 vdso_pagelist); 173 if (ret) { 174 mm->context.vdso = NULL; 175 goto up_fail; 176 } 177 178 up_fail: 179 up_write(&mm->mmap_sem); 180 181 return ret; 182 } 183 184 const char *arch_vma_name(struct vm_area_struct *vma) 185 { 186 /* 187 * We can re-use the vdso pointer in mm_context_t for identifying 188 * the vectors page for compat applications. The vDSO will always 189 * sit above TASK_UNMAPPED_BASE and so we don't need to worry about 190 * it conflicting with the vectors base. 191 */ 192 if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) { 193 #ifdef CONFIG_COMPAT 194 if (vma->vm_start == AARCH32_VECTORS_BASE) 195 return "[vectors]"; 196 #endif 197 return "[vdso]"; 198 } 199 200 return NULL; 201 } 202 203 /* 204 * We define AT_SYSINFO_EHDR, so we need these function stubs to keep 205 * Linux happy. 206 */ 207 int in_gate_area_no_mm(unsigned long addr) 208 { 209 return 0; 210 } 211 212 int in_gate_area(struct mm_struct *mm, unsigned long addr) 213 { 214 return 0; 215 } 216 217 struct vm_area_struct *get_gate_vma(struct mm_struct *mm) 218 { 219 return NULL; 220 } 221 222 /* 223 * Update the vDSO data page to keep in sync with kernel timekeeping. 224 */ 225 void update_vsyscall(struct timespec *ts, struct timespec *wtm, 226 struct clocksource *clock, u32 mult) 227 { 228 struct timespec xtime_coarse; 229 u32 use_syscall = strcmp(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 = clock->cycle_last; 241 vdso_data->xtime_clock_sec = ts->tv_sec; 242 vdso_data->xtime_clock_nsec = ts->tv_nsec; 243 vdso_data->cs_mult = mult; 244 vdso_data->cs_shift = clock->shift; 245 vdso_data->wtm_clock_sec = wtm->tv_sec; 246 vdso_data->wtm_clock_nsec = wtm->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