1 /* 2 * Copyright (C) 2015 Imagination Technologies 3 * Author: Alex Smith <alex.smith@imgtec.com> 4 * 5 * This program is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License as published by the 7 * Free Software Foundation; either version 2 of the License, or (at your 8 * option) any later version. 9 */ 10 11 #include <linux/binfmts.h> 12 #include <linux/elf.h> 13 #include <linux/err.h> 14 #include <linux/init.h> 15 #include <linux/ioport.h> 16 #include <linux/kernel.h> 17 #include <linux/mm.h> 18 #include <linux/random.h> 19 #include <linux/sched.h> 20 #include <linux/slab.h> 21 #include <linux/timekeeper_internal.h> 22 23 #include <asm/abi.h> 24 #include <asm/mips-cps.h> 25 #include <asm/page.h> 26 #include <asm/vdso.h> 27 28 /* Kernel-provided data used by the VDSO. */ 29 static union mips_vdso_data vdso_data __page_aligned_data; 30 31 /* 32 * Mapping for the VDSO data/GIC pages. The real pages are mapped manually, as 33 * what we map and where within the area they are mapped is determined at 34 * runtime. 35 */ 36 static struct page *no_pages[] = { NULL }; 37 static struct vm_special_mapping vdso_vvar_mapping = { 38 .name = "[vvar]", 39 .pages = no_pages, 40 }; 41 42 static void __init init_vdso_image(struct mips_vdso_image *image) 43 { 44 unsigned long num_pages, i; 45 unsigned long data_pfn; 46 47 BUG_ON(!PAGE_ALIGNED(image->data)); 48 BUG_ON(!PAGE_ALIGNED(image->size)); 49 50 num_pages = image->size / PAGE_SIZE; 51 52 data_pfn = __phys_to_pfn(__pa_symbol(image->data)); 53 for (i = 0; i < num_pages; i++) 54 image->mapping.pages[i] = pfn_to_page(data_pfn + i); 55 } 56 57 static int __init init_vdso(void) 58 { 59 init_vdso_image(&vdso_image); 60 61 #ifdef CONFIG_MIPS32_O32 62 init_vdso_image(&vdso_image_o32); 63 #endif 64 65 #ifdef CONFIG_MIPS32_N32 66 init_vdso_image(&vdso_image_n32); 67 #endif 68 69 return 0; 70 } 71 subsys_initcall(init_vdso); 72 73 void update_vsyscall(struct timekeeper *tk) 74 { 75 vdso_data_write_begin(&vdso_data); 76 77 vdso_data.xtime_sec = tk->xtime_sec; 78 vdso_data.xtime_nsec = tk->tkr_mono.xtime_nsec; 79 vdso_data.wall_to_mono_sec = tk->wall_to_monotonic.tv_sec; 80 vdso_data.wall_to_mono_nsec = tk->wall_to_monotonic.tv_nsec; 81 vdso_data.cs_shift = tk->tkr_mono.shift; 82 83 vdso_data.clock_mode = tk->tkr_mono.clock->archdata.vdso_clock_mode; 84 if (vdso_data.clock_mode != VDSO_CLOCK_NONE) { 85 vdso_data.cs_mult = tk->tkr_mono.mult; 86 vdso_data.cs_cycle_last = tk->tkr_mono.cycle_last; 87 vdso_data.cs_mask = tk->tkr_mono.mask; 88 } 89 90 vdso_data_write_end(&vdso_data); 91 } 92 93 void update_vsyscall_tz(void) 94 { 95 if (vdso_data.clock_mode != VDSO_CLOCK_NONE) { 96 vdso_data.tz_minuteswest = sys_tz.tz_minuteswest; 97 vdso_data.tz_dsttime = sys_tz.tz_dsttime; 98 } 99 } 100 101 static unsigned long vdso_base(void) 102 { 103 unsigned long base; 104 105 /* Skip the delay slot emulation page */ 106 base = STACK_TOP + PAGE_SIZE; 107 108 if (current->flags & PF_RANDOMIZE) { 109 base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1); 110 base = PAGE_ALIGN(base); 111 } 112 113 return base; 114 } 115 116 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 117 { 118 struct mips_vdso_image *image = current->thread.abi->vdso; 119 struct mm_struct *mm = current->mm; 120 unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr, gic_pfn; 121 struct vm_area_struct *vma; 122 int ret; 123 124 if (down_write_killable(&mm->mmap_sem)) 125 return -EINTR; 126 127 /* Map delay slot emulation page */ 128 base = mmap_region(NULL, STACK_TOP, PAGE_SIZE, 129 VM_READ | VM_EXEC | 130 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, 131 0, NULL); 132 if (IS_ERR_VALUE(base)) { 133 ret = base; 134 goto out; 135 } 136 137 /* 138 * Determine total area size. This includes the VDSO data itself, the 139 * data page, and the GIC user page if present. Always create a mapping 140 * for the GIC user area if the GIC is present regardless of whether it 141 * is the current clocksource, in case it comes into use later on. We 142 * only map a page even though the total area is 64K, as we only need 143 * the counter registers at the start. 144 */ 145 gic_size = mips_gic_present() ? PAGE_SIZE : 0; 146 vvar_size = gic_size + PAGE_SIZE; 147 size = vvar_size + image->size; 148 149 /* 150 * Find a region that's large enough for us to perform the 151 * colour-matching alignment below. 152 */ 153 if (cpu_has_dc_aliases) 154 size += shm_align_mask + 1; 155 156 base = get_unmapped_area(NULL, vdso_base(), size, 0, 0); 157 if (IS_ERR_VALUE(base)) { 158 ret = base; 159 goto out; 160 } 161 162 /* 163 * If we suffer from dcache aliasing, ensure that the VDSO data page 164 * mapping is coloured the same as the kernel's mapping of that memory. 165 * This ensures that when the kernel updates the VDSO data userland 166 * will observe it without requiring cache invalidations. 167 */ 168 if (cpu_has_dc_aliases) { 169 base = __ALIGN_MASK(base, shm_align_mask); 170 base += ((unsigned long)&vdso_data - gic_size) & shm_align_mask; 171 } 172 173 data_addr = base + gic_size; 174 vdso_addr = data_addr + PAGE_SIZE; 175 176 vma = _install_special_mapping(mm, base, vvar_size, 177 VM_READ | VM_MAYREAD, 178 &vdso_vvar_mapping); 179 if (IS_ERR(vma)) { 180 ret = PTR_ERR(vma); 181 goto out; 182 } 183 184 /* Map GIC user page. */ 185 if (gic_size) { 186 gic_pfn = virt_to_phys(mips_gic_base + MIPS_GIC_USER_OFS) >> PAGE_SHIFT; 187 188 ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size, 189 pgprot_noncached(PAGE_READONLY)); 190 if (ret) 191 goto out; 192 } 193 194 /* Map data page. */ 195 ret = remap_pfn_range(vma, data_addr, 196 virt_to_phys(&vdso_data) >> PAGE_SHIFT, 197 PAGE_SIZE, PAGE_READONLY); 198 if (ret) 199 goto out; 200 201 /* Map VDSO image. */ 202 vma = _install_special_mapping(mm, vdso_addr, image->size, 203 VM_READ | VM_EXEC | 204 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, 205 &image->mapping); 206 if (IS_ERR(vma)) { 207 ret = PTR_ERR(vma); 208 goto out; 209 } 210 211 mm->context.vdso = (void *)vdso_addr; 212 ret = 0; 213 214 out: 215 up_write(&mm->mmap_sem); 216 return ret; 217 } 218