// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp. * <benh@kernel.crashing.org> * Copyright (C) 2012 ARM Limited * Copyright (C) 2015 Regents of the University of California */ #include <linux/elf.h> #include <linux/mm.h> #include <linux/slab.h> #include <linux/binfmts.h> #include <linux/err.h> #include <asm/vdso.h> extern char vdso_start[], vdso_end[]; static unsigned int vdso_pages; static struct page **vdso_pagelist; /* * The vDSO data page. */ static union { struct vdso_data data; u8 page[PAGE_SIZE]; } vdso_data_store __page_aligned_data; static struct vdso_data *vdso_data = &vdso_data_store.data; static int __init vdso_init(void) { unsigned int i; vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT; vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL); if (unlikely(vdso_pagelist == NULL)) { pr_err("vdso: pagelist allocation failed\n"); return -ENOMEM; } for (i = 0; i < vdso_pages; i++) { struct page *pg; pg = virt_to_page(vdso_start + (i << PAGE_SHIFT)); vdso_pagelist[i] = pg; } vdso_pagelist[i] = virt_to_page(vdso_data); return 0; } arch_initcall(vdso_init); int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) { struct mm_struct *mm = current->mm; unsigned long vdso_base, vdso_len; int ret; vdso_len = (vdso_pages + 1) << PAGE_SHIFT; down_write(&mm->mmap_sem); vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0); if (IS_ERR_VALUE(vdso_base)) { ret = vdso_base; goto end; } /* * Put vDSO base into mm struct. We need to do this before calling * install_special_mapping or the perf counter mmap tracking code * will fail to recognise it as a vDSO (since arch_vma_name fails). */ mm->context.vdso = (void *)vdso_base; ret = install_special_mapping(mm, vdso_base, vdso_len, (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC), vdso_pagelist); if (unlikely(ret)) mm->context.vdso = NULL; end: up_write(&mm->mmap_sem); return ret; } const char *arch_vma_name(struct vm_area_struct *vma) { if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso)) return "[vdso]"; return NULL; }