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 static struct vm_special_mapping spec = { 92 .name = "[vectors]", 93 .pages = vectors_page, 94 95 }; 96 void *ret; 97 98 down_write(&mm->mmap_sem); 99 current->mm->context.vdso = (void *)addr; 100 101 /* Map vectors page at the high address. */ 102 ret = _install_special_mapping(mm, addr, PAGE_SIZE, 103 VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC, 104 &spec); 105 106 up_write(&mm->mmap_sem); 107 108 return PTR_ERR_OR_ZERO(ret); 109 } 110 #endif /* CONFIG_COMPAT */ 111 112 static struct vm_special_mapping vdso_spec[2]; 113 114 static int __init vdso_init(void) 115 { 116 int i; 117 118 if (memcmp(&vdso_start, "\177ELF", 4)) { 119 pr_err("vDSO is not a valid ELF object!\n"); 120 return -EINVAL; 121 } 122 123 vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT; 124 pr_info("vdso: %ld pages (%ld code @ %p, %ld data @ %p)\n", 125 vdso_pages + 1, vdso_pages, &vdso_start, 1L, vdso_data); 126 127 /* Allocate the vDSO pagelist, plus a page for the data. */ 128 vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *), 129 GFP_KERNEL); 130 if (vdso_pagelist == NULL) 131 return -ENOMEM; 132 133 /* Grab the vDSO data page. */ 134 vdso_pagelist[0] = virt_to_page(vdso_data); 135 136 /* Grab the vDSO code pages. */ 137 for (i = 0; i < vdso_pages; i++) 138 vdso_pagelist[i + 1] = virt_to_page(&vdso_start + i * PAGE_SIZE); 139 140 /* Populate the special mapping structures */ 141 vdso_spec[0] = (struct vm_special_mapping) { 142 .name = "[vvar]", 143 .pages = vdso_pagelist, 144 }; 145 146 vdso_spec[1] = (struct vm_special_mapping) { 147 .name = "[vdso]", 148 .pages = &vdso_pagelist[1], 149 }; 150 151 return 0; 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_text_len, vdso_mapping_len; 160 void *ret; 161 162 vdso_text_len = vdso_pages << PAGE_SHIFT; 163 /* Be sure to map the data page */ 164 vdso_mapping_len = vdso_text_len + PAGE_SIZE; 165 166 down_write(&mm->mmap_sem); 167 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 168 if (IS_ERR_VALUE(vdso_base)) { 169 ret = ERR_PTR(vdso_base); 170 goto up_fail; 171 } 172 ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE, 173 VM_READ|VM_MAYREAD, 174 &vdso_spec[0]); 175 if (IS_ERR(ret)) 176 goto up_fail; 177 178 vdso_base += PAGE_SIZE; 179 mm->context.vdso = (void *)vdso_base; 180 ret = _install_special_mapping(mm, vdso_base, vdso_text_len, 181 VM_READ|VM_EXEC| 182 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 183 &vdso_spec[1]); 184 if (IS_ERR(ret)) 185 goto up_fail; 186 187 188 up_write(&mm->mmap_sem); 189 return 0; 190 191 up_fail: 192 mm->context.vdso = NULL; 193 up_write(&mm->mmap_sem); 194 return PTR_ERR(ret); 195 } 196 197 /* 198 * Update the vDSO data page to keep in sync with kernel timekeeping. 199 */ 200 void update_vsyscall(struct timekeeper *tk) 201 { 202 u32 use_syscall = strcmp(tk->tkr_mono.clock->name, "arch_sys_counter"); 203 204 ++vdso_data->tb_seq_count; 205 smp_wmb(); 206 207 vdso_data->use_syscall = use_syscall; 208 vdso_data->xtime_coarse_sec = tk->xtime_sec; 209 vdso_data->xtime_coarse_nsec = tk->tkr_mono.xtime_nsec >> 210 tk->tkr_mono.shift; 211 vdso_data->wtm_clock_sec = tk->wall_to_monotonic.tv_sec; 212 vdso_data->wtm_clock_nsec = tk->wall_to_monotonic.tv_nsec; 213 214 if (!use_syscall) { 215 vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last; 216 vdso_data->xtime_clock_sec = tk->xtime_sec; 217 vdso_data->xtime_clock_nsec = tk->tkr_mono.xtime_nsec; 218 vdso_data->cs_mult = tk->tkr_mono.mult; 219 vdso_data->cs_shift = tk->tkr_mono.shift; 220 } 221 222 smp_wmb(); 223 ++vdso_data->tb_seq_count; 224 } 225 226 void update_vsyscall_tz(void) 227 { 228 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; 229 vdso_data->tz_dsttime = sys_tz.tz_dsttime; 230 } 231