| 1 | // SPDX-License-Identifier: GPL-2.0-only |
|---|---|
| 2 | /* |
| 3 | * Copyright (C) 2011 Richard Weinberger <richrd@nod.at> |
| 4 | */ |
| 5 | |
| 6 | #include <linux/slab.h> |
| 7 | #include <linux/sched.h> |
| 8 | #include <linux/mm.h> |
| 9 | #include <asm/page.h> |
| 10 | #include <asm/elf.h> |
| 11 | #include <linux/init.h> |
| 12 | |
| 13 | static unsigned int __read_mostly vdso_enabled = 1; |
| 14 | unsigned long um_vdso_addr; |
| 15 | |
| 16 | extern unsigned long task_size; |
| 17 | extern char vdso_start[], vdso_end[]; |
| 18 | |
| 19 | static struct page **vdsop; |
| 20 | |
| 21 | static int __init init_vdso(void) |
| 22 | { |
| 23 | struct page *um_vdso; |
| 24 | |
| 25 | BUG_ON(vdso_end - vdso_start > PAGE_SIZE); |
| 26 | |
| 27 | um_vdso_addr = task_size - PAGE_SIZE; |
| 28 | |
| 29 | vdsop = kmalloc(size: sizeof(struct page *), GFP_KERNEL); |
| 30 | if (!vdsop) |
| 31 | goto oom; |
| 32 | |
| 33 | um_vdso = alloc_page(GFP_KERNEL); |
| 34 | if (!um_vdso) { |
| 35 | kfree(objp: vdsop); |
| 36 | |
| 37 | goto oom; |
| 38 | } |
| 39 | |
| 40 | copy_page(page_address(um_vdso), from: vdso_start); |
| 41 | *vdsop = um_vdso; |
| 42 | |
| 43 | return 0; |
| 44 | |
| 45 | oom: |
| 46 | printk(KERN_ERR "Cannot allocate vdso\n"); |
| 47 | vdso_enabled = 0; |
| 48 | |
| 49 | return -ENOMEM; |
| 50 | } |
| 51 | subsys_initcall(init_vdso); |
| 52 | |
| 53 | int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
| 54 | { |
| 55 | int err; |
| 56 | struct mm_struct *mm = current->mm; |
| 57 | |
| 58 | if (!vdso_enabled) |
| 59 | return 0; |
| 60 | |
| 61 | if (mmap_write_lock_killable(mm)) |
| 62 | return -EINTR; |
| 63 | |
| 64 | err = install_special_mapping(mm, addr: um_vdso_addr, PAGE_SIZE, |
| 65 | VM_READ|VM_EXEC| |
| 66 | VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, |
| 67 | pages: vdsop); |
| 68 | |
| 69 | mmap_write_unlock(mm); |
| 70 | |
| 71 | return err; |
| 72 | } |
| 73 |