1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp. 4 * <benh@kernel.crashing.org> 5 * Copyright (C) 2012 ARM Limited 6 * Copyright (C) 2015 Regents of the University of California 7 */ 8 9 #include <linux/mm.h> 10 #include <linux/slab.h> 11 #include <linux/binfmts.h> 12 #include <linux/err.h> 13 14 #include <asm/vdso.h> 15 16 extern char vdso_start[], vdso_end[]; 17 18 static unsigned int vdso_pages; 19 static struct page **vdso_pagelist; 20 21 /* 22 * The vDSO data page. 23 */ 24 static union { 25 struct vdso_data data; 26 u8 page[PAGE_SIZE]; 27 } vdso_data_store __page_aligned_data; 28 struct vdso_data *vdso_data = &vdso_data_store.data; 29 30 static int __init vdso_init(void) 31 { 32 unsigned int i; 33 34 vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT; 35 vdso_pagelist = 36 kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL); 37 if (unlikely(vdso_pagelist == NULL)) { 38 pr_err("vdso: pagelist allocation failed\n"); 39 return -ENOMEM; 40 } 41 42 for (i = 0; i < vdso_pages; i++) { 43 struct page *pg; 44 45 pg = virt_to_page(vdso_start + (i << PAGE_SHIFT)); 46 vdso_pagelist[i] = pg; 47 } 48 vdso_pagelist[i] = virt_to_page(vdso_data); 49 50 return 0; 51 } 52 arch_initcall(vdso_init); 53 54 int arch_setup_additional_pages(struct linux_binprm *bprm, 55 int uses_interp) 56 { 57 struct mm_struct *mm = current->mm; 58 unsigned long vdso_base, vdso_len; 59 int ret; 60 61 vdso_len = (vdso_pages + 1) << PAGE_SHIFT; 62 63 down_write(&mm->mmap_sem); 64 vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0); 65 if (IS_ERR_VALUE(vdso_base)) { 66 ret = vdso_base; 67 goto end; 68 } 69 70 /* 71 * Put vDSO base into mm struct. We need to do this before calling 72 * install_special_mapping or the perf counter mmap tracking code 73 * will fail to recognise it as a vDSO (since arch_vma_name fails). 74 */ 75 mm->context.vdso = (void *)vdso_base; 76 77 ret = install_special_mapping(mm, vdso_base, vdso_len, 78 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC), 79 vdso_pagelist); 80 81 if (unlikely(ret)) 82 mm->context.vdso = NULL; 83 84 end: 85 up_write(&mm->mmap_sem); 86 return ret; 87 } 88 89 const char *arch_vma_name(struct vm_area_struct *vma) 90 { 91 if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso)) 92 return "[vdso]"; 93 return NULL; 94 } 95