1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
|
/*
* (C) Copyright 2002 Linus Torvalds
* Portions based on the vdso-randomization code from exec-shield:
* Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar
*
* This file contains the needed initializations to support sysenter.
*/
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/thread_info.h>
#include <linux/sched.h>
#include <linux/gfp.h>
#include <linux/string.h>
#include <linux/elf.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/module.h>
#include <asm/cpufeature.h>
#include <asm/msr.h>
#include <asm/pgtable.h>
#include <asm/unistd.h>
#include <asm/elf.h>
#include <asm/tlbflush.h>
#include <asm/vdso.h>
#include <asm/proto.h>
#ifdef CONFIG_COMPAT_VDSO
#define VDSO_DEFAULT 0
#else
#define VDSO_DEFAULT 1
#endif
#ifdef CONFIG_X86_64
#define vdso_enabled sysctl_vsyscall32
#define arch_setup_additional_pages syscall32_setup_pages
#endif
/*
* Should the kernel map a VDSO page into processes and pass its
* address down to glibc upon exec()?
*/
unsigned int __read_mostly vdso_enabled = VDSO_DEFAULT;
static int __init vdso_setup(char *s)
{
vdso_enabled = simple_strtoul(s, NULL, 0);
if (vdso_enabled > 1)
pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n");
return 1;
}
/*
* For consistency, the argument vdso32=[012] affects the 32-bit vDSO
* behavior on both 64-bit and 32-bit kernels.
* On 32-bit kernels, vdso=[012] means the same thing.
*/
__setup("vdso32=", vdso_setup);
#ifdef CONFIG_X86_32
__setup_param("vdso=", vdso32_setup, vdso_setup, 0);
EXPORT_SYMBOL_GPL(vdso_enabled);
#endif
static struct page *vdso32_pages[1];
#ifdef CONFIG_X86_64
#define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SYSENTER32))
#define vdso32_syscall() (boot_cpu_has(X86_FEATURE_SYSCALL32))
/* May not be __init: called during resume */
void syscall32_cpu_init(void)
{
/* Load these always in case some future AMD CPU supports
SYSENTER from compat mode too. */
wrmsrl_safe(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);
wrmsrl_safe(MSR_IA32_SYSENTER_ESP, 0ULL);
wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target);
wrmsrl(MSR_CSTAR, ia32_cstar_target);
}
#else /* CONFIG_X86_32 */
#define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SEP))
#define vdso32_syscall() (0)
void enable_sep_cpu(void)
{
int cpu = get_cpu();
struct tss_struct *tss = &per_cpu(init_tss, cpu);
if (!boot_cpu_has(X86_FEATURE_SEP)) {
put_cpu();
return;
}
tss->x86_tss.ss1 = __KERNEL_CS;
tss->x86_tss.sp1 = sizeof(struct tss_struct) + (unsigned long) tss;
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
wrmsr(MSR_IA32_SYSENTER_ESP, tss->x86_tss.sp1, 0);
wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) ia32_sysenter_target, 0);
put_cpu();
}
#endif /* CONFIG_X86_64 */
int __init sysenter_setup(void)
{
void *vdso_page = (void *)get_zeroed_page(GFP_ATOMIC);
const void *vdso;
size_t vdso_len;
vdso32_pages[0] = virt_to_page(vdso_page);
if (vdso32_syscall()) {
vdso = &vdso32_syscall_start;
vdso_len = &vdso32_syscall_end - &vdso32_syscall_start;
} else if (vdso32_sysenter()){
vdso = &vdso32_sysenter_start;
vdso_len = &vdso32_sysenter_end - &vdso32_sysenter_start;
} else {
vdso = &vdso32_int80_start;
vdso_len = &vdso32_int80_end - &vdso32_int80_start;
}
memcpy(vdso_page, vdso, vdso_len);
patch_vdso32(vdso_page, vdso_len);
return 0;
}
/* Setup a VMA at program startup for the vsyscall page */
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mm_struct *mm = current->mm;
unsigned long addr;
int ret = 0;
#ifdef CONFIG_X86_X32_ABI
if (test_thread_flag(TIF_X32))
return x32_setup_additional_pages(bprm, uses_interp);
#endif
if (vdso_enabled != 1) /* Other values all mean "disabled" */
return 0;
down_write(&mm->mmap_sem);
addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
if (IS_ERR_VALUE(addr)) {
ret = addr;
goto up_fail;
}
current->mm->context.vdso = (void *)addr;
/*
* MAYWRITE to allow gdb to COW and set breakpoints
*/
ret = install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdso32_pages);
if (ret)
goto up_fail;
current_thread_info()->sysenter_return =
VDSO32_SYMBOL(addr, SYSENTER_RETURN);
up_fail:
if (ret)
current->mm->context.vdso = NULL;
up_write(&mm->mmap_sem);
return ret;
}
#ifdef CONFIG_X86_64
subsys_initcall(sysenter_setup);
#ifdef CONFIG_SYSCTL
/* Register vsyscall32 into the ABI table */
#include <linux/sysctl.h>
static struct ctl_table abi_table2[] = {
{
.procname = "vsyscall32",
.data = &sysctl_vsyscall32,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{}
};
static struct ctl_table abi_root_table2[] = {
{
.procname = "abi",
.mode = 0555,
.child = abi_table2
},
{}
};
static __init int ia32_binfmt_init(void)
{
register_sysctl_table(abi_root_table2);
return 0;
}
__initcall(ia32_binfmt_init);
#endif
#else /* CONFIG_X86_32 */
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;
}
struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
return NULL;
}
int in_gate_area(struct mm_struct *mm, unsigned long addr)
{
return 0;
}
int in_gate_area_no_mm(unsigned long addr)
{
return 0;
}
#endif /* CONFIG_X86_64 */
|
