1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright (C) 2015 Imagination Technologies 4 * Author: Alex Smith <alex.smith@imgtec.com> 5 */ 6 7 #include <linux/binfmts.h> 8 #include <linux/elf.h> 9 #include <linux/err.h> 10 #include <linux/init.h> 11 #include <linux/ioport.h> 12 #include <linux/kernel.h> 13 #include <linux/mm.h> 14 #include <linux/random.h> 15 #include <linux/sched.h> 16 #include <linux/slab.h> 17 #include <linux/timekeeper_internal.h> 18 19 #include <asm/abi.h> 20 #include <asm/mips-cps.h> 21 #include <asm/page.h> 22 #include <asm/vdso.h> 23 #include <vdso/helpers.h> 24 #include <vdso/vsyscall.h> 25 26 /* Kernel-provided data used by the VDSO. */ 27 static union mips_vdso_data mips_vdso_data __page_aligned_data; 28 struct vdso_data *vdso_data = mips_vdso_data.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 static unsigned long vdso_base(void) 73 { 74 unsigned long base; 75 76 /* Skip the delay slot emulation page */ 77 base = STACK_TOP + PAGE_SIZE; 78 79 if (current->flags & PF_RANDOMIZE) { 80 base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1); 81 base = PAGE_ALIGN(base); 82 } 83 84 return base; 85 } 86 87 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 88 { 89 struct mips_vdso_image *image = current->thread.abi->vdso; 90 struct mm_struct *mm = current->mm; 91 unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr, gic_pfn; 92 struct vm_area_struct *vma; 93 int ret; 94 95 if (down_write_killable(&mm->mmap_sem)) 96 return -EINTR; 97 98 /* Map delay slot emulation page */ 99 base = mmap_region(NULL, STACK_TOP, PAGE_SIZE, 100 VM_READ | VM_EXEC | 101 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, 102 0, NULL); 103 if (IS_ERR_VALUE(base)) { 104 ret = base; 105 goto out; 106 } 107 108 /* 109 * Determine total area size. This includes the VDSO data itself, the 110 * data page, and the GIC user page if present. Always create a mapping 111 * for the GIC user area if the GIC is present regardless of whether it 112 * is the current clocksource, in case it comes into use later on. We 113 * only map a page even though the total area is 64K, as we only need 114 * the counter registers at the start. 115 */ 116 gic_size = mips_gic_present() ? PAGE_SIZE : 0; 117 vvar_size = gic_size + PAGE_SIZE; 118 size = vvar_size + image->size; 119 120 /* 121 * Find a region that's large enough for us to perform the 122 * colour-matching alignment below. 123 */ 124 if (cpu_has_dc_aliases) 125 size += shm_align_mask + 1; 126 127 base = get_unmapped_area(NULL, vdso_base(), size, 0, 0); 128 if (IS_ERR_VALUE(base)) { 129 ret = base; 130 goto out; 131 } 132 133 /* 134 * If we suffer from dcache aliasing, ensure that the VDSO data page 135 * mapping is coloured the same as the kernel's mapping of that memory. 136 * This ensures that when the kernel updates the VDSO data userland 137 * will observe it without requiring cache invalidations. 138 */ 139 if (cpu_has_dc_aliases) { 140 base = __ALIGN_MASK(base, shm_align_mask); 141 base += ((unsigned long)vdso_data - gic_size) & shm_align_mask; 142 } 143 144 data_addr = base + gic_size; 145 vdso_addr = data_addr + PAGE_SIZE; 146 147 vma = _install_special_mapping(mm, base, vvar_size, 148 VM_READ | VM_MAYREAD, 149 &vdso_vvar_mapping); 150 if (IS_ERR(vma)) { 151 ret = PTR_ERR(vma); 152 goto out; 153 } 154 155 /* Map GIC user page. */ 156 if (gic_size) { 157 gic_pfn = virt_to_phys(mips_gic_base + MIPS_GIC_USER_OFS) >> PAGE_SHIFT; 158 159 ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size, 160 pgprot_noncached(PAGE_READONLY)); 161 if (ret) 162 goto out; 163 } 164 165 /* Map data page. */ 166 ret = remap_pfn_range(vma, data_addr, 167 virt_to_phys(vdso_data) >> PAGE_SHIFT, 168 PAGE_SIZE, PAGE_READONLY); 169 if (ret) 170 goto out; 171 172 /* Map VDSO image. */ 173 vma = _install_special_mapping(mm, vdso_addr, image->size, 174 VM_READ | VM_EXEC | 175 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, 176 &image->mapping); 177 if (IS_ERR(vma)) { 178 ret = PTR_ERR(vma); 179 goto out; 180 } 181 182 mm->context.vdso = (void *)vdso_addr; 183 ret = 0; 184 185 out: 186 up_write(&mm->mmap_sem); 187 return ret; 188 } 189