Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 | 2 | * (C) Copyright 2002 Linus Torvalds |
e6e5494c IM |
3 | * Portions based on the vdso-randomization code from exec-shield: |
4 | * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar | |
1da177e4 LT |
5 | * |
6 | * This file contains the needed initializations to support sysenter. | |
7 | */ | |
8 | ||
9 | #include <linux/init.h> | |
10 | #include <linux/smp.h> | |
11 | #include <linux/thread_info.h> | |
12 | #include <linux/sched.h> | |
13 | #include <linux/gfp.h> | |
14 | #include <linux/string.h> | |
15 | #include <linux/elf.h> | |
e6e5494c | 16 | #include <linux/mm.h> |
4e950f6f | 17 | #include <linux/err.h> |
e6e5494c | 18 | #include <linux/module.h> |
1da177e4 LT |
19 | |
20 | #include <asm/cpufeature.h> | |
21 | #include <asm/msr.h> | |
22 | #include <asm/pgtable.h> | |
23 | #include <asm/unistd.h> | |
d4f7a2c1 | 24 | #include <asm/elf.h> |
1dbf527c | 25 | #include <asm/tlbflush.h> |
6c3652ef | 26 | #include <asm/vdso.h> |
1dbf527c JF |
27 | |
28 | enum { | |
29 | VDSO_DISABLED = 0, | |
30 | VDSO_ENABLED = 1, | |
31 | VDSO_COMPAT = 2, | |
32 | }; | |
33 | ||
34 | #ifdef CONFIG_COMPAT_VDSO | |
35 | #define VDSO_DEFAULT VDSO_COMPAT | |
36 | #else | |
37 | #define VDSO_DEFAULT VDSO_ENABLED | |
38 | #endif | |
1da177e4 | 39 | |
e6e5494c IM |
40 | /* |
41 | * Should the kernel map a VDSO page into processes and pass its | |
42 | * address down to glibc upon exec()? | |
43 | */ | |
1dbf527c | 44 | unsigned int __read_mostly vdso_enabled = VDSO_DEFAULT; |
e6e5494c IM |
45 | |
46 | EXPORT_SYMBOL_GPL(vdso_enabled); | |
47 | ||
48 | static int __init vdso_setup(char *s) | |
49 | { | |
50 | vdso_enabled = simple_strtoul(s, NULL, 0); | |
51 | ||
52 | return 1; | |
53 | } | |
54 | ||
55 | __setup("vdso=", vdso_setup); | |
56 | ||
0aa97fb2 | 57 | extern asmlinkage void ia32_sysenter_target(void); |
1da177e4 | 58 | |
d4f7a2c1 JF |
59 | static __init void reloc_symtab(Elf32_Ehdr *ehdr, |
60 | unsigned offset, unsigned size) | |
61 | { | |
62 | Elf32_Sym *sym = (void *)ehdr + offset; | |
63 | unsigned nsym = size / sizeof(*sym); | |
64 | unsigned i; | |
65 | ||
66 | for(i = 0; i < nsym; i++, sym++) { | |
67 | if (sym->st_shndx == SHN_UNDEF || | |
68 | sym->st_shndx == SHN_ABS) | |
69 | continue; /* skip */ | |
70 | ||
71 | if (sym->st_shndx > SHN_LORESERVE) { | |
72 | printk(KERN_INFO "VDSO: unexpected st_shndx %x\n", | |
73 | sym->st_shndx); | |
74 | continue; | |
75 | } | |
76 | ||
77 | switch(ELF_ST_TYPE(sym->st_info)) { | |
78 | case STT_OBJECT: | |
79 | case STT_FUNC: | |
80 | case STT_SECTION: | |
81 | case STT_FILE: | |
82 | sym->st_value += VDSO_HIGH_BASE; | |
83 | } | |
84 | } | |
85 | } | |
86 | ||
87 | static __init void reloc_dyn(Elf32_Ehdr *ehdr, unsigned offset) | |
88 | { | |
89 | Elf32_Dyn *dyn = (void *)ehdr + offset; | |
90 | ||
91 | for(; dyn->d_tag != DT_NULL; dyn++) | |
92 | switch(dyn->d_tag) { | |
93 | case DT_PLTGOT: | |
94 | case DT_HASH: | |
95 | case DT_STRTAB: | |
96 | case DT_SYMTAB: | |
97 | case DT_RELA: | |
98 | case DT_INIT: | |
99 | case DT_FINI: | |
100 | case DT_REL: | |
101 | case DT_DEBUG: | |
102 | case DT_JMPREL: | |
103 | case DT_VERSYM: | |
104 | case DT_VERDEF: | |
105 | case DT_VERNEED: | |
106 | case DT_ADDRRNGLO ... DT_ADDRRNGHI: | |
107 | /* definitely pointers needing relocation */ | |
108 | dyn->d_un.d_ptr += VDSO_HIGH_BASE; | |
109 | break; | |
110 | ||
111 | case DT_ENCODING ... OLD_DT_LOOS-1: | |
112 | case DT_LOOS ... DT_HIOS-1: | |
113 | /* Tags above DT_ENCODING are pointers if | |
114 | they're even */ | |
115 | if (dyn->d_tag >= DT_ENCODING && | |
116 | (dyn->d_tag & 1) == 0) | |
117 | dyn->d_un.d_ptr += VDSO_HIGH_BASE; | |
118 | break; | |
119 | ||
120 | case DT_VERDEFNUM: | |
121 | case DT_VERNEEDNUM: | |
122 | case DT_FLAGS_1: | |
123 | case DT_RELACOUNT: | |
124 | case DT_RELCOUNT: | |
125 | case DT_VALRNGLO ... DT_VALRNGHI: | |
126 | /* definitely not pointers */ | |
127 | break; | |
128 | ||
129 | case OLD_DT_LOOS ... DT_LOOS-1: | |
130 | case DT_HIOS ... DT_VALRNGLO-1: | |
131 | default: | |
132 | if (dyn->d_tag > DT_ENCODING) | |
133 | printk(KERN_INFO "VDSO: unexpected DT_tag %x\n", | |
134 | dyn->d_tag); | |
135 | break; | |
136 | } | |
137 | } | |
138 | ||
139 | static __init void relocate_vdso(Elf32_Ehdr *ehdr) | |
140 | { | |
141 | Elf32_Phdr *phdr; | |
142 | Elf32_Shdr *shdr; | |
143 | int i; | |
144 | ||
145 | BUG_ON(memcmp(ehdr->e_ident, ELFMAG, 4) != 0 || | |
146 | !elf_check_arch(ehdr) || | |
147 | ehdr->e_type != ET_DYN); | |
148 | ||
149 | ehdr->e_entry += VDSO_HIGH_BASE; | |
150 | ||
151 | /* rebase phdrs */ | |
152 | phdr = (void *)ehdr + ehdr->e_phoff; | |
153 | for (i = 0; i < ehdr->e_phnum; i++) { | |
154 | phdr[i].p_vaddr += VDSO_HIGH_BASE; | |
155 | ||
156 | /* relocate dynamic stuff */ | |
157 | if (phdr[i].p_type == PT_DYNAMIC) | |
158 | reloc_dyn(ehdr, phdr[i].p_offset); | |
159 | } | |
160 | ||
161 | /* rebase sections */ | |
162 | shdr = (void *)ehdr + ehdr->e_shoff; | |
163 | for(i = 0; i < ehdr->e_shnum; i++) { | |
164 | if (!(shdr[i].sh_flags & SHF_ALLOC)) | |
165 | continue; | |
166 | ||
167 | shdr[i].sh_addr += VDSO_HIGH_BASE; | |
168 | ||
169 | if (shdr[i].sh_type == SHT_SYMTAB || | |
170 | shdr[i].sh_type == SHT_DYNSYM) | |
171 | reloc_symtab(ehdr, shdr[i].sh_offset, | |
172 | shdr[i].sh_size); | |
173 | } | |
174 | } | |
d4f7a2c1 | 175 | |
6fe940d6 | 176 | void enable_sep_cpu(void) |
1da177e4 LT |
177 | { |
178 | int cpu = get_cpu(); | |
179 | struct tss_struct *tss = &per_cpu(init_tss, cpu); | |
180 | ||
6fe940d6 LS |
181 | if (!boot_cpu_has(X86_FEATURE_SEP)) { |
182 | put_cpu(); | |
183 | return; | |
184 | } | |
185 | ||
a75c54f9 RR |
186 | tss->x86_tss.ss1 = __KERNEL_CS; |
187 | tss->x86_tss.esp1 = sizeof(struct tss_struct) + (unsigned long) tss; | |
1da177e4 | 188 | wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0); |
a75c54f9 | 189 | wrmsr(MSR_IA32_SYSENTER_ESP, tss->x86_tss.esp1, 0); |
0aa97fb2 | 190 | wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) ia32_sysenter_target, 0); |
1da177e4 LT |
191 | put_cpu(); |
192 | } | |
193 | ||
1dbf527c JF |
194 | static struct vm_area_struct gate_vma; |
195 | ||
196 | static int __init gate_vma_init(void) | |
197 | { | |
198 | gate_vma.vm_mm = NULL; | |
199 | gate_vma.vm_start = FIXADDR_USER_START; | |
200 | gate_vma.vm_end = FIXADDR_USER_END; | |
201 | gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; | |
202 | gate_vma.vm_page_prot = __P101; | |
203 | /* | |
204 | * Make sure the vDSO gets into every core dump. | |
205 | * Dumping its contents makes post-mortem fully interpretable later | |
206 | * without matching up the same kernel and hardware config to see | |
207 | * what PC values meant. | |
208 | */ | |
209 | gate_vma.vm_flags |= VM_ALWAYSDUMP; | |
210 | return 0; | |
211 | } | |
212 | ||
1da177e4 LT |
213 | /* |
214 | * These symbols are defined by vsyscall.o to mark the bounds | |
215 | * of the ELF DSO images included therein. | |
216 | */ | |
217 | extern const char vsyscall_int80_start, vsyscall_int80_end; | |
218 | extern const char vsyscall_sysenter_start, vsyscall_sysenter_end; | |
7d91d531 | 219 | static struct page *syscall_pages[1]; |
1da177e4 | 220 | |
1dbf527c JF |
221 | static void map_compat_vdso(int map) |
222 | { | |
223 | static int vdso_mapped; | |
224 | ||
225 | if (map == vdso_mapped) | |
226 | return; | |
227 | ||
228 | vdso_mapped = map; | |
229 | ||
230 | __set_fixmap(FIX_VDSO, page_to_pfn(syscall_pages[0]) << PAGE_SHIFT, | |
231 | map ? PAGE_READONLY_EXEC : PAGE_NONE); | |
232 | ||
233 | /* flush stray tlbs */ | |
234 | flush_tlb_all(); | |
235 | } | |
236 | ||
a6c4e076 | 237 | int __init sysenter_setup(void) |
1da177e4 | 238 | { |
7d91d531 | 239 | void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC); |
d4f7a2c1 JF |
240 | const void *vsyscall; |
241 | size_t vsyscall_len; | |
242 | ||
7d91d531 | 243 | syscall_pages[0] = virt_to_page(syscall_page); |
1da177e4 | 244 | |
1dbf527c JF |
245 | gate_vma_init(); |
246 | ||
e6e5494c | 247 | printk("Compat vDSO mapped to %08lx.\n", __fix_to_virt(FIX_VDSO)); |
1da177e4 LT |
248 | |
249 | if (!boot_cpu_has(X86_FEATURE_SEP)) { | |
d4f7a2c1 JF |
250 | vsyscall = &vsyscall_int80_start; |
251 | vsyscall_len = &vsyscall_int80_end - &vsyscall_int80_start; | |
252 | } else { | |
253 | vsyscall = &vsyscall_sysenter_start; | |
254 | vsyscall_len = &vsyscall_sysenter_end - &vsyscall_sysenter_start; | |
1da177e4 LT |
255 | } |
256 | ||
d4f7a2c1 JF |
257 | memcpy(syscall_page, vsyscall, vsyscall_len); |
258 | relocate_vdso(syscall_page); | |
1da177e4 | 259 | |
1da177e4 LT |
260 | return 0; |
261 | } | |
e6e5494c | 262 | |
e6e5494c IM |
263 | /* Setup a VMA at program startup for the vsyscall page */ |
264 | int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack) | |
265 | { | |
e6e5494c IM |
266 | struct mm_struct *mm = current->mm; |
267 | unsigned long addr; | |
752783c0 | 268 | int ret = 0; |
1dbf527c | 269 | bool compat; |
e6e5494c IM |
270 | |
271 | down_write(&mm->mmap_sem); | |
e6e5494c | 272 | |
1dbf527c JF |
273 | /* Test compat mode once here, in case someone |
274 | changes it via sysctl */ | |
275 | compat = (vdso_enabled == VDSO_COMPAT); | |
276 | ||
277 | map_compat_vdso(compat); | |
278 | ||
279 | if (compat) | |
280 | addr = VDSO_HIGH_BASE; | |
281 | else { | |
282 | addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); | |
283 | if (IS_ERR_VALUE(addr)) { | |
284 | ret = addr; | |
285 | goto up_fail; | |
286 | } | |
287 | ||
288 | /* | |
289 | * MAYWRITE to allow gdb to COW and set breakpoints | |
290 | * | |
291 | * Make sure the vDSO gets into every core dump. | |
292 | * Dumping its contents makes post-mortem fully | |
293 | * interpretable later without matching up the same | |
294 | * kernel and hardware config to see what PC values | |
295 | * meant. | |
296 | */ | |
297 | ret = install_special_mapping(mm, addr, PAGE_SIZE, | |
298 | VM_READ|VM_EXEC| | |
299 | VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC| | |
300 | VM_ALWAYSDUMP, | |
301 | syscall_pages); | |
302 | ||
303 | if (ret) | |
304 | goto up_fail; | |
305 | } | |
e6e5494c IM |
306 | |
307 | current->mm->context.vdso = (void *)addr; | |
308 | current_thread_info()->sysenter_return = | |
6c3652ef | 309 | VDSO32_SYMBOL(addr, SYSENTER_RETURN); |
1dbf527c JF |
310 | |
311 | up_fail: | |
e6e5494c | 312 | up_write(&mm->mmap_sem); |
1dbf527c | 313 | |
e6e5494c | 314 | return ret; |
e6e5494c IM |
315 | } |
316 | ||
317 | const char *arch_vma_name(struct vm_area_struct *vma) | |
318 | { | |
319 | if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) | |
320 | return "[vdso]"; | |
321 | return NULL; | |
322 | } | |
323 | ||
324 | struct vm_area_struct *get_gate_vma(struct task_struct *tsk) | |
325 | { | |
1dbf527c JF |
326 | struct mm_struct *mm = tsk->mm; |
327 | ||
328 | /* Check to see if this task was created in compat vdso mode */ | |
329 | if (mm && mm->context.vdso == (void *)VDSO_HIGH_BASE) | |
330 | return &gate_vma; | |
e6e5494c IM |
331 | return NULL; |
332 | } | |
333 | ||
334 | int in_gate_area(struct task_struct *task, unsigned long addr) | |
335 | { | |
2f30c007 JB |
336 | const struct vm_area_struct *vma = get_gate_vma(task); |
337 | ||
338 | return vma && addr >= vma->vm_start && addr < vma->vm_end; | |
e6e5494c IM |
339 | } |
340 | ||
341 | int in_gate_area_no_task(unsigned long addr) | |
342 | { | |
343 | return 0; | |
344 | } |