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1da177e4 LT |
1 | /* |
2 | * linux/arch/i386/kernel/sysenter.c | |
3 | * | |
4 | * (C) Copyright 2002 Linus Torvalds | |
e6e5494c IM |
5 | * Portions based on the vdso-randomization code from exec-shield: |
6 | * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar | |
1da177e4 LT |
7 | * |
8 | * This file contains the needed initializations to support sysenter. | |
9 | */ | |
10 | ||
11 | #include <linux/init.h> | |
12 | #include <linux/smp.h> | |
13 | #include <linux/thread_info.h> | |
14 | #include <linux/sched.h> | |
15 | #include <linux/gfp.h> | |
16 | #include <linux/string.h> | |
17 | #include <linux/elf.h> | |
e6e5494c IM |
18 | #include <linux/mm.h> |
19 | #include <linux/module.h> | |
1da177e4 LT |
20 | |
21 | #include <asm/cpufeature.h> | |
22 | #include <asm/msr.h> | |
23 | #include <asm/pgtable.h> | |
24 | #include <asm/unistd.h> | |
25 | ||
e6e5494c IM |
26 | /* |
27 | * Should the kernel map a VDSO page into processes and pass its | |
28 | * address down to glibc upon exec()? | |
29 | */ | |
30 | unsigned int __read_mostly vdso_enabled = 1; | |
31 | ||
32 | EXPORT_SYMBOL_GPL(vdso_enabled); | |
33 | ||
34 | static int __init vdso_setup(char *s) | |
35 | { | |
36 | vdso_enabled = simple_strtoul(s, NULL, 0); | |
37 | ||
38 | return 1; | |
39 | } | |
40 | ||
41 | __setup("vdso=", vdso_setup); | |
42 | ||
1da177e4 LT |
43 | extern asmlinkage void sysenter_entry(void); |
44 | ||
6fe940d6 | 45 | void enable_sep_cpu(void) |
1da177e4 LT |
46 | { |
47 | int cpu = get_cpu(); | |
48 | struct tss_struct *tss = &per_cpu(init_tss, cpu); | |
49 | ||
6fe940d6 LS |
50 | if (!boot_cpu_has(X86_FEATURE_SEP)) { |
51 | put_cpu(); | |
52 | return; | |
53 | } | |
54 | ||
1da177e4 LT |
55 | tss->ss1 = __KERNEL_CS; |
56 | tss->esp1 = sizeof(struct tss_struct) + (unsigned long) tss; | |
57 | wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0); | |
58 | wrmsr(MSR_IA32_SYSENTER_ESP, tss->esp1, 0); | |
59 | wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) sysenter_entry, 0); | |
60 | put_cpu(); | |
61 | } | |
62 | ||
63 | /* | |
64 | * These symbols are defined by vsyscall.o to mark the bounds | |
65 | * of the ELF DSO images included therein. | |
66 | */ | |
67 | extern const char vsyscall_int80_start, vsyscall_int80_end; | |
68 | extern const char vsyscall_sysenter_start, vsyscall_sysenter_end; | |
e6e5494c | 69 | static void *syscall_page; |
1da177e4 | 70 | |
6fe940d6 | 71 | int __init sysenter_setup(void) |
1da177e4 | 72 | { |
e6e5494c | 73 | syscall_page = (void *)get_zeroed_page(GFP_ATOMIC); |
1da177e4 | 74 | |
e6e5494c IM |
75 | #ifdef CONFIG_COMPAT_VDSO |
76 | __set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_READONLY); | |
77 | printk("Compat vDSO mapped to %08lx.\n", __fix_to_virt(FIX_VDSO)); | |
78 | #else | |
79 | /* | |
80 | * In the non-compat case the ELF coredumping code needs the fixmap: | |
81 | */ | |
82 | __set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_KERNEL_RO); | |
83 | #endif | |
1da177e4 LT |
84 | |
85 | if (!boot_cpu_has(X86_FEATURE_SEP)) { | |
e6e5494c | 86 | memcpy(syscall_page, |
1da177e4 LT |
87 | &vsyscall_int80_start, |
88 | &vsyscall_int80_end - &vsyscall_int80_start); | |
89 | return 0; | |
90 | } | |
91 | ||
e6e5494c | 92 | memcpy(syscall_page, |
1da177e4 LT |
93 | &vsyscall_sysenter_start, |
94 | &vsyscall_sysenter_end - &vsyscall_sysenter_start); | |
95 | ||
1da177e4 LT |
96 | return 0; |
97 | } | |
e6e5494c IM |
98 | |
99 | static struct page *syscall_nopage(struct vm_area_struct *vma, | |
100 | unsigned long adr, int *type) | |
101 | { | |
102 | struct page *p = virt_to_page(adr - vma->vm_start + syscall_page); | |
103 | get_page(p); | |
104 | return p; | |
105 | } | |
106 | ||
107 | /* Prevent VMA merging */ | |
108 | static void syscall_vma_close(struct vm_area_struct *vma) | |
109 | { | |
110 | } | |
111 | ||
112 | static struct vm_operations_struct syscall_vm_ops = { | |
113 | .close = syscall_vma_close, | |
114 | .nopage = syscall_nopage, | |
115 | }; | |
116 | ||
117 | /* Defined in vsyscall-sysenter.S */ | |
118 | extern void SYSENTER_RETURN; | |
119 | ||
120 | /* Setup a VMA at program startup for the vsyscall page */ | |
121 | int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack) | |
122 | { | |
123 | struct vm_area_struct *vma; | |
124 | struct mm_struct *mm = current->mm; | |
125 | unsigned long addr; | |
126 | int ret; | |
127 | ||
128 | down_write(&mm->mmap_sem); | |
129 | addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); | |
130 | if (IS_ERR_VALUE(addr)) { | |
131 | ret = addr; | |
132 | goto up_fail; | |
133 | } | |
134 | ||
e94b1766 | 135 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
e6e5494c IM |
136 | if (!vma) { |
137 | ret = -ENOMEM; | |
138 | goto up_fail; | |
139 | } | |
140 | ||
141 | vma->vm_start = addr; | |
142 | vma->vm_end = addr + PAGE_SIZE; | |
143 | /* MAYWRITE to allow gdb to COW and set breakpoints */ | |
144 | vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC|VM_MAYWRITE; | |
145 | vma->vm_flags |= mm->def_flags; | |
146 | vma->vm_page_prot = protection_map[vma->vm_flags & 7]; | |
147 | vma->vm_ops = &syscall_vm_ops; | |
148 | vma->vm_mm = mm; | |
149 | ||
150 | ret = insert_vm_struct(mm, vma); | |
79bc79b0 | 151 | if (unlikely(ret)) { |
152 | kmem_cache_free(vm_area_cachep, vma); | |
153 | goto up_fail; | |
154 | } | |
e6e5494c IM |
155 | |
156 | current->mm->context.vdso = (void *)addr; | |
157 | current_thread_info()->sysenter_return = | |
158 | (void *)VDSO_SYM(&SYSENTER_RETURN); | |
159 | mm->total_vm++; | |
160 | up_fail: | |
161 | up_write(&mm->mmap_sem); | |
162 | return ret; | |
e6e5494c IM |
163 | } |
164 | ||
165 | const char *arch_vma_name(struct vm_area_struct *vma) | |
166 | { | |
167 | if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) | |
168 | return "[vdso]"; | |
169 | return NULL; | |
170 | } | |
171 | ||
172 | struct vm_area_struct *get_gate_vma(struct task_struct *tsk) | |
173 | { | |
174 | return NULL; | |
175 | } | |
176 | ||
177 | int in_gate_area(struct task_struct *task, unsigned long addr) | |
178 | { | |
179 | return 0; | |
180 | } | |
181 | ||
182 | int in_gate_area_no_task(unsigned long addr) | |
183 | { | |
184 | return 0; | |
185 | } |