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 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 struct vm_special_mapping vdso_spec[2]; 114 115 static int __init vdso_init(void) 116 { 117 int i; 118 119 if (memcmp(&vdso_start, "\177ELF", 4)) { 120 pr_err("vDSO is not a valid ELF object!\n"); 121 return -EINVAL; 122 } 123 124 vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT; 125 pr_info("vdso: %ld pages (%ld code @ %p, %ld data @ %p)\n", 126 vdso_pages + 1, vdso_pages, &vdso_start, 1L, vdso_data); 127 128 /* Allocate the vDSO pagelist, plus a page for the data. */ 129 vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *), 130 GFP_KERNEL); 131 if (vdso_pagelist == NULL) 132 return -ENOMEM; 133 134 /* Grab the vDSO data page. */ 135 vdso_pagelist[0] = pfn_to_page(PHYS_PFN(__pa(vdso_data))); 136 137 /* Grab the vDSO code pages. */ 138 for (i = 0; i < vdso_pages; i++) 139 vdso_pagelist[i + 1] = pfn_to_page(PHYS_PFN(__pa(&vdso_start)) + i); 140 141 /* Populate the special mapping structures */ 142 vdso_spec[0] = (struct vm_special_mapping) { 143 .name = "[vvar]", 144 .pages = vdso_pagelist, 145 }; 146 147 vdso_spec[1] = (struct vm_special_mapping) { 148 .name = "[vdso]", 149 .pages = &vdso_pagelist[1], 150 }; 151 152 return 0; 153 } 154 arch_initcall(vdso_init); 155 156 int arch_setup_additional_pages(struct linux_binprm *bprm, 157 int uses_interp) 158 { 159 struct mm_struct *mm = current->mm; 160 unsigned long vdso_base, vdso_text_len, vdso_mapping_len; 161 void *ret; 162 163 vdso_text_len = vdso_pages << PAGE_SHIFT; 164 /* Be sure to map the data page */ 165 vdso_mapping_len = vdso_text_len + PAGE_SIZE; 166 167 if (down_write_killable(&mm->mmap_sem)) 168 return -EINTR; 169 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 170 if (IS_ERR_VALUE(vdso_base)) { 171 ret = ERR_PTR(vdso_base); 172 goto up_fail; 173 } 174 ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE, 175 VM_READ|VM_MAYREAD, 176 &vdso_spec[0]); 177 if (IS_ERR(ret)) 178 goto up_fail; 179 180 vdso_base += PAGE_SIZE; 181 mm->context.vdso = (void *)vdso_base; 182 ret = _install_special_mapping(mm, vdso_base, vdso_text_len, 183 VM_READ|VM_EXEC| 184 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 185 &vdso_spec[1]); 186 if (IS_ERR(ret)) 187 goto up_fail; 188 189 190 up_write(&mm->mmap_sem); 191 return 0; 192 193 up_fail: 194 mm->context.vdso = NULL; 195 up_write(&mm->mmap_sem); 196 return PTR_ERR(ret); 197 } 198 199 /* 200 * Update the vDSO data page to keep in sync with kernel timekeeping. 201 */ 202 void update_vsyscall(struct timekeeper *tk) 203 { 204 u32 use_syscall = strcmp(tk->tkr_mono.clock->name, "arch_sys_counter"); 205 206 ++vdso_data->tb_seq_count; 207 smp_wmb(); 208 209 vdso_data->use_syscall = use_syscall; 210 vdso_data->xtime_coarse_sec = tk->xtime_sec; 211 vdso_data->xtime_coarse_nsec = tk->tkr_mono.xtime_nsec >> 212 tk->tkr_mono.shift; 213 vdso_data->wtm_clock_sec = tk->wall_to_monotonic.tv_sec; 214 vdso_data->wtm_clock_nsec = tk->wall_to_monotonic.tv_nsec; 215 216 if (!use_syscall) { 217 vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last; 218 vdso_data->xtime_clock_sec = tk->xtime_sec; 219 vdso_data->xtime_clock_nsec = tk->tkr_mono.xtime_nsec; 220 vdso_data->cs_mult = tk->tkr_mono.mult; 221 vdso_data->cs_shift = tk->tkr_mono.shift; 222 } 223 224 smp_wmb(); 225 ++vdso_data->tb_seq_count; 226 } 227 228 void update_vsyscall_tz(void) 229 { 230 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; 231 vdso_data->tz_dsttime = sys_tz.tz_dsttime; 232 } 233