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/elf.h> 10 #include <linux/mm.h> 11 #include <linux/slab.h> 12 #include <linux/binfmts.h> 13 #include <linux/err.h> 14 15 #include <asm/vdso.h> 16 17 extern char vdso_start[], vdso_end[]; 18 19 static unsigned int vdso_pages; 20 static struct page **vdso_pagelist; 21 22 /* 23 * The vDSO data page. 24 */ 25 static union { 26 struct vdso_data data; 27 u8 page[PAGE_SIZE]; 28 } vdso_data_store __page_aligned_data; 29 static struct vdso_data *vdso_data = &vdso_data_store.data; 30 31 static int __init vdso_init(void) 32 { 33 unsigned int i; 34 35 vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT; 36 vdso_pagelist = 37 kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL); 38 if (unlikely(vdso_pagelist == NULL)) { 39 pr_err("vdso: pagelist allocation failed\n"); 40 return -ENOMEM; 41 } 42 43 for (i = 0; i < vdso_pages; i++) { 44 struct page *pg; 45 46 pg = virt_to_page(vdso_start + (i << PAGE_SHIFT)); 47 vdso_pagelist[i] = pg; 48 } 49 vdso_pagelist[i] = virt_to_page(vdso_data); 50 51 return 0; 52 } 53 arch_initcall(vdso_init); 54 55 int arch_setup_additional_pages(struct linux_binprm *bprm, 56 int uses_interp) 57 { 58 struct mm_struct *mm = current->mm; 59 unsigned long vdso_base, vdso_len; 60 int ret; 61 62 vdso_len = (vdso_pages + 1) << PAGE_SHIFT; 63 64 down_write(&mm->mmap_sem); 65 vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0); 66 if (IS_ERR_VALUE(vdso_base)) { 67 ret = vdso_base; 68 goto end; 69 } 70 71 /* 72 * Put vDSO base into mm struct. We need to do this before calling 73 * install_special_mapping or the perf counter mmap tracking code 74 * will fail to recognise it as a vDSO (since arch_vma_name fails). 75 */ 76 mm->context.vdso = (void *)vdso_base; 77 78 ret = install_special_mapping(mm, vdso_base, vdso_len, 79 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC), 80 vdso_pagelist); 81 82 if (unlikely(ret)) 83 mm->context.vdso = NULL; 84 85 end: 86 up_write(&mm->mmap_sem); 87 return ret; 88 } 89 90 const char *arch_vma_name(struct vm_area_struct *vma) 91 { 92 if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso)) 93 return "[vdso]"; 94 return NULL; 95 } 96