1 /* 2 * Copyright (C) 2011 Richard Weinberger <richrd@nod.at> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 */ 8 9 #include <linux/slab.h> 10 #include <linux/sched.h> 11 #include <linux/mm.h> 12 #include <asm/page.h> 13 #include <asm/elf.h> 14 #include <linux/init.h> 15 16 static unsigned int __read_mostly vdso_enabled = 1; 17 unsigned long um_vdso_addr; 18 19 extern unsigned long task_size; 20 extern char vdso_start[], vdso_end[]; 21 22 static struct page **vdsop; 23 24 static int __init init_vdso(void) 25 { 26 struct page *um_vdso; 27 28 BUG_ON(vdso_end - vdso_start > PAGE_SIZE); 29 30 um_vdso_addr = task_size - PAGE_SIZE; 31 32 vdsop = kmalloc(sizeof(struct page *), GFP_KERNEL); 33 if (!vdsop) 34 goto oom; 35 36 um_vdso = alloc_page(GFP_KERNEL); 37 if (!um_vdso) { 38 kfree(vdsop); 39 40 goto oom; 41 } 42 43 copy_page(page_address(um_vdso), vdso_start); 44 *vdsop = um_vdso; 45 46 return 0; 47 48 oom: 49 printk(KERN_ERR "Cannot allocate vdso\n"); 50 vdso_enabled = 0; 51 52 return -ENOMEM; 53 } 54 subsys_initcall(init_vdso); 55 56 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 57 { 58 int err; 59 struct mm_struct *mm = current->mm; 60 61 if (!vdso_enabled) 62 return 0; 63 64 down_write(&mm->mmap_sem); 65 66 err = install_special_mapping(mm, um_vdso_addr, PAGE_SIZE, 67 VM_READ|VM_EXEC| 68 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 69 vdsop); 70 71 up_write(&mm->mmap_sem); 72 73 return err; 74 } 75