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 18 #include <asm/abi.h> 19 #include <asm/mips-cps.h> 20 #include <asm/page.h> 21 #include <asm/vdso.h> 22 #include <vdso/helpers.h> 23 #include <vdso/vsyscall.h> 24 25 /* Kernel-provided data used by the VDSO. */ 26 static union vdso_data_store mips_vdso_data __page_aligned_data; 27 struct vdso_data *vdso_data = mips_vdso_data.data; 28 29 /* 30 * Mapping for the VDSO data/GIC pages. The real pages are mapped manually, as 31 * what we map and where within the area they are mapped is determined at 32 * runtime. 33 */ 34 static struct page *no_pages[] = { NULL }; 35 static struct vm_special_mapping vdso_vvar_mapping = { 36 .name = "[vvar]", 37 .pages = no_pages, 38 }; 39 40 static void __init init_vdso_image(struct mips_vdso_image *image) 41 { 42 unsigned long num_pages, i; 43 unsigned long data_pfn; 44 45 BUG_ON(!PAGE_ALIGNED(image->data)); 46 BUG_ON(!PAGE_ALIGNED(image->size)); 47 48 num_pages = image->size / PAGE_SIZE; 49 50 data_pfn = __phys_to_pfn(__pa_symbol(image->data)); 51 for (i = 0; i < num_pages; i++) 52 image->mapping.pages[i] = pfn_to_page(data_pfn + i); 53 } 54 55 static int __init init_vdso(void) 56 { 57 init_vdso_image(&vdso_image); 58 59 #ifdef CONFIG_MIPS32_O32 60 init_vdso_image(&vdso_image_o32); 61 #endif 62 63 #ifdef CONFIG_MIPS32_N32 64 init_vdso_image(&vdso_image_n32); 65 #endif 66 67 return 0; 68 } 69 subsys_initcall(init_vdso); 70 71 static unsigned long vdso_base(void) 72 { 73 unsigned long base = STACK_TOP; 74 75 if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) { 76 /* Skip the delay slot emulation page */ 77 base += PAGE_SIZE; 78 } 79 80 if (current->flags & PF_RANDOMIZE) { 81 base += get_random_u32_below(VDSO_RANDOMIZE_SIZE); 82 base = PAGE_ALIGN(base); 83 } 84 85 return base; 86 } 87 88 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 89 { 90 struct mips_vdso_image *image = current->thread.abi->vdso; 91 struct mm_struct *mm = current->mm; 92 unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr, gic_pfn, gic_base; 93 struct vm_area_struct *vma; 94 int ret; 95 96 if (mmap_write_lock_killable(mm)) 97 return -EINTR; 98 99 if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) { 100 /* Map delay slot emulation page */ 101 base = mmap_region(NULL, STACK_TOP, PAGE_SIZE, 102 VM_READ | VM_EXEC | 103 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, 104 0, NULL); 105 if (IS_ERR_VALUE(base)) { 106 ret = base; 107 goto out; 108 } 109 } 110 111 /* 112 * Determine total area size. This includes the VDSO data itself, the 113 * data page, and the GIC user page if present. Always create a mapping 114 * for the GIC user area if the GIC is present regardless of whether it 115 * is the current clocksource, in case it comes into use later on. We 116 * only map a page even though the total area is 64K, as we only need 117 * the counter registers at the start. 118 */ 119 gic_size = mips_gic_present() ? PAGE_SIZE : 0; 120 vvar_size = gic_size + PAGE_SIZE; 121 size = vvar_size + image->size; 122 123 /* 124 * Find a region that's large enough for us to perform the 125 * colour-matching alignment below. 126 */ 127 if (cpu_has_dc_aliases) 128 size += shm_align_mask + 1; 129 130 base = get_unmapped_area(NULL, vdso_base(), size, 0, 0); 131 if (IS_ERR_VALUE(base)) { 132 ret = base; 133 goto out; 134 } 135 136 /* 137 * If we suffer from dcache aliasing, ensure that the VDSO data page 138 * mapping is coloured the same as the kernel's mapping of that memory. 139 * This ensures that when the kernel updates the VDSO data userland 140 * will observe it without requiring cache invalidations. 141 */ 142 if (cpu_has_dc_aliases) { 143 base = __ALIGN_MASK(base, shm_align_mask); 144 base += ((unsigned long)vdso_data - gic_size) & shm_align_mask; 145 } 146 147 data_addr = base + gic_size; 148 vdso_addr = data_addr + PAGE_SIZE; 149 150 vma = _install_special_mapping(mm, base, vvar_size, 151 VM_READ | VM_MAYREAD, 152 &vdso_vvar_mapping); 153 if (IS_ERR(vma)) { 154 ret = PTR_ERR(vma); 155 goto out; 156 } 157 158 /* Map GIC user page. */ 159 if (gic_size) { 160 gic_base = (unsigned long)mips_gic_base + MIPS_GIC_USER_OFS; 161 gic_pfn = PFN_DOWN(__pa(gic_base)); 162 163 ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size, 164 pgprot_noncached(vma->vm_page_prot)); 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, vma->vm_page_prot); 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