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