Commit | Line | Data |
---|---|---|
19f9a34f | 1 | /* |
58862699 | 2 | * arch/sh/kernel/vsyscall/vsyscall.c |
19f9a34f PM |
3 | * |
4 | * Copyright (C) 2006 Paul Mundt | |
5 | * | |
6 | * vDSO randomization | |
7 | * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar | |
8 | * | |
9 | * This file is subject to the terms and conditions of the GNU General Public | |
10 | * License. See the file "COPYING" in the main directory of this archive | |
11 | * for more details. | |
12 | */ | |
13 | #include <linux/mm.h> | |
19f9a34f PM |
14 | #include <linux/kernel.h> |
15 | #include <linux/init.h> | |
16 | #include <linux/gfp.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/elf.h> | |
f75522ce | 19 | #include <linux/sched.h> |
e06c4e57 | 20 | #include <linux/err.h> |
19f9a34f PM |
21 | |
22 | /* | |
23 | * Should the kernel map a VDSO page into processes and pass its | |
24 | * address down to glibc upon exec()? | |
25 | */ | |
26 | unsigned int __read_mostly vdso_enabled = 1; | |
27 | EXPORT_SYMBOL_GPL(vdso_enabled); | |
28 | ||
29 | static int __init vdso_setup(char *s) | |
30 | { | |
31 | vdso_enabled = simple_strtoul(s, NULL, 0); | |
32 | return 1; | |
33 | } | |
34 | __setup("vdso=", vdso_setup); | |
35 | ||
36 | /* | |
37 | * These symbols are defined by vsyscall.o to mark the bounds | |
38 | * of the ELF DSO images included therein. | |
39 | */ | |
40 | extern const char vsyscall_trapa_start, vsyscall_trapa_end; | |
2affc857 | 41 | static struct page *syscall_pages[1]; |
19f9a34f PM |
42 | |
43 | int __init vsyscall_init(void) | |
44 | { | |
2affc857 PM |
45 | void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC); |
46 | syscall_pages[0] = virt_to_page(syscall_page); | |
19f9a34f PM |
47 | |
48 | /* | |
49 | * XXX: Map this page to a fixmap entry if we get around | |
50 | * to adding the page to ELF core dumps | |
51 | */ | |
52 | ||
53 | memcpy(syscall_page, | |
54 | &vsyscall_trapa_start, | |
55 | &vsyscall_trapa_end - &vsyscall_trapa_start); | |
56 | ||
57 | return 0; | |
58 | } | |
59 | ||
19f9a34f | 60 | /* Setup a VMA at program startup for the vsyscall page */ |
fc5243d9 | 61 | int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
19f9a34f | 62 | { |
19f9a34f PM |
63 | struct mm_struct *mm = current->mm; |
64 | unsigned long addr; | |
65 | int ret; | |
66 | ||
69048176 MH |
67 | if (down_write_killable(&mm->mmap_sem)) |
68 | return -EINTR; | |
69 | ||
19f9a34f PM |
70 | addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); |
71 | if (IS_ERR_VALUE(addr)) { | |
72 | ret = addr; | |
73 | goto up_fail; | |
74 | } | |
75 | ||
2affc857 PM |
76 | ret = install_special_mapping(mm, addr, PAGE_SIZE, |
77 | VM_READ | VM_EXEC | | |
909af768 | 78 | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, |
2affc857 PM |
79 | syscall_pages); |
80 | if (unlikely(ret)) | |
19f9a34f | 81 | goto up_fail; |
19f9a34f PM |
82 | |
83 | current->mm->context.vdso = (void *)addr; | |
84 | ||
19f9a34f PM |
85 | up_fail: |
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 | ||
95 | return NULL; | |
96 | } |