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 = STACK_TOP; 75 76 if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) { 77 /* Skip the delay slot emulation page */ 78 base += PAGE_SIZE; 79 } 80 81 if (current->flags & PF_RANDOMIZE) { 82 base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1); 83 base = PAGE_ALIGN(base); 84 } 85 86 return base; 87 } 88 89 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 90 { 91 struct mips_vdso_image *image = current->thread.abi->vdso; 92 struct mm_struct *mm = current->mm; 93 unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr, gic_pfn; 94 struct vm_area_struct *vma; 95 int ret; 96 97 if (mmap_write_lock_killable(mm)) 98 return -EINTR; 99 100 if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) { 101 /* Map delay slot emulation page */ 102 base = mmap_region(NULL, STACK_TOP, PAGE_SIZE, 103 VM_READ | VM_EXEC | 104 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, 105 0, NULL); 106 if (IS_ERR_VALUE(base)) { 107 ret = base; 108 goto out; 109 } 110 } 111 112 /* 113 * Determine total area size. This includes the VDSO data itself, the 114 * data page, and the GIC user page if present. Always create a mapping 115 * for the GIC user area if the GIC is present regardless of whether it 116 * is the current clocksource, in case it comes into use later on. We 117 * only map a page even though the total area is 64K, as we only need 118 * the counter registers at the start. 119 */ 120 gic_size = mips_gic_present() ? PAGE_SIZE : 0; 121 vvar_size = gic_size + PAGE_SIZE; 122 size = vvar_size + image->size; 123 124 /* 125 * Find a region that's large enough for us to perform the 126 * colour-matching alignment below. 127 */ 128 if (cpu_has_dc_aliases) 129 size += shm_align_mask + 1; 130 131 base = get_unmapped_area(NULL, vdso_base(), size, 0, 0); 132 if (IS_ERR_VALUE(base)) { 133 ret = base; 134 goto out; 135 } 136 137 /* 138 * If we suffer from dcache aliasing, ensure that the VDSO data page 139 * mapping is coloured the same as the kernel's mapping of that memory. 140 * This ensures that when the kernel updates the VDSO data userland 141 * will observe it without requiring cache invalidations. 142 */ 143 if (cpu_has_dc_aliases) { 144 base = __ALIGN_MASK(base, shm_align_mask); 145 base += ((unsigned long)vdso_data - gic_size) & shm_align_mask; 146 } 147 148 data_addr = base + gic_size; 149 vdso_addr = data_addr + PAGE_SIZE; 150 151 vma = _install_special_mapping(mm, base, vvar_size, 152 VM_READ | VM_MAYREAD, 153 &vdso_vvar_mapping); 154 if (IS_ERR(vma)) { 155 ret = PTR_ERR(vma); 156 goto out; 157 } 158 159 /* Map GIC user page. */ 160 if (gic_size) { 161 gic_pfn = virt_to_phys(mips_gic_base + MIPS_GIC_USER_OFS) >> PAGE_SHIFT; 162 163 ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size, 164 pgprot_noncached(PAGE_READONLY)); 165 if (ret) 166 goto out; 167 } 168 169 /* Map data page. */ 170 ret = remap_pfn_range(vma, data_addr, 171 virt_to_phys(vdso_data) >> PAGE_SHIFT, 172 PAGE_SIZE, PAGE_READONLY); 173 if (ret) 174 goto out; 175 176 /* Map VDSO image. */ 177 vma = _install_special_mapping(mm, vdso_addr, image->size, 178 VM_READ | VM_EXEC | 179 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, 180 &image->mapping); 181 if (IS_ERR(vma)) { 182 ret = PTR_ERR(vma); 183 goto out; 184 } 185 186 mm->context.vdso = (void *)vdso_addr; 187 ret = 0; 188 189 out: 190 mmap_write_unlock(mm); 191 return ret; 192 } 193