Merge branch 'upstream' into upstream-jgarzik
[linux-2.6] / arch / sh / kernel / vsyscall / vsyscall.c
1 /*
2  * arch/sh/kernel/vsyscall.c
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>
14 #include <linux/slab.h>
15 #include <linux/kernel.h>
16 #include <linux/init.h>
17 #include <linux/gfp.h>
18 #include <linux/module.h>
19 #include <linux/elf.h>
20
21 /*
22  * Should the kernel map a VDSO page into processes and pass its
23  * address down to glibc upon exec()?
24  */
25 unsigned int __read_mostly vdso_enabled = 1;
26 EXPORT_SYMBOL_GPL(vdso_enabled);
27
28 static int __init vdso_setup(char *s)
29 {
30         vdso_enabled = simple_strtoul(s, NULL, 0);
31         return 1;
32 }
33 __setup("vdso=", vdso_setup);
34
35 /*
36  * These symbols are defined by vsyscall.o to mark the bounds
37  * of the ELF DSO images included therein.
38  */
39 extern const char vsyscall_trapa_start, vsyscall_trapa_end;
40 static struct page *syscall_pages[1];
41
42 int __init vsyscall_init(void)
43 {
44         void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
45         syscall_pages[0] = virt_to_page(syscall_page);
46
47         /*
48          * XXX: Map this page to a fixmap entry if we get around
49          * to adding the page to ELF core dumps
50          */
51
52         memcpy(syscall_page,
53                &vsyscall_trapa_start,
54                &vsyscall_trapa_end - &vsyscall_trapa_start);
55
56         return 0;
57 }
58
59 /* Setup a VMA at program startup for the vsyscall page */
60 int arch_setup_additional_pages(struct linux_binprm *bprm,
61                                 int executable_stack)
62 {
63         struct mm_struct *mm = current->mm;
64         unsigned long addr;
65         int ret;
66
67         down_write(&mm->mmap_sem);
68         addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
69         if (IS_ERR_VALUE(addr)) {
70                 ret = addr;
71                 goto up_fail;
72         }
73
74         ret = install_special_mapping(mm, addr, PAGE_SIZE,
75                                       VM_READ | VM_EXEC |
76                                       VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC |
77                                       VM_ALWAYSDUMP,
78                                       syscall_pages);
79         if (unlikely(ret))
80                 goto up_fail;
81
82         current->mm->context.vdso = (void *)addr;
83
84 up_fail:
85         up_write(&mm->mmap_sem);
86         return ret;
87 }
88
89 const char *arch_vma_name(struct vm_area_struct *vma)
90 {
91         if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
92                 return "[vdso]";
93
94         return NULL;
95 }
96
97 struct vm_area_struct *get_gate_vma(struct task_struct *task)
98 {
99         return NULL;
100 }
101
102 int in_gate_area(struct task_struct *task, unsigned long address)
103 {
104         return 0;
105 }
106
107 int in_gate_area_no_task(unsigned long address)
108 {
109         return 0;
110 }