Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzi...
[linux-2.6] / arch / x86 / vdso / vdso32-setup.c
1 /*
2  * (C) Copyright 2002 Linus Torvalds
3  * Portions based on the vdso-randomization code from exec-shield:
4  * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar
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>
16 #include <linux/mm.h>
17 #include <linux/err.h>
18 #include <linux/module.h>
19
20 #include <asm/cpufeature.h>
21 #include <asm/msr.h>
22 #include <asm/pgtable.h>
23 #include <asm/unistd.h>
24 #include <asm/elf.h>
25 #include <asm/tlbflush.h>
26 #include <asm/vdso.h>
27 #include <asm/proto.h>
28
29 enum {
30         VDSO_DISABLED = 0,
31         VDSO_ENABLED = 1,
32         VDSO_COMPAT = 2,
33 };
34
35 #ifdef CONFIG_COMPAT_VDSO
36 #define VDSO_DEFAULT    VDSO_COMPAT
37 #else
38 #define VDSO_DEFAULT    VDSO_ENABLED
39 #endif
40
41 #ifdef CONFIG_X86_64
42 #define vdso_enabled                    sysctl_vsyscall32
43 #define arch_setup_additional_pages     syscall32_setup_pages
44 #endif
45
46 /*
47  * This is the difference between the prelinked addresses in the vDSO images
48  * and the VDSO_HIGH_BASE address where CONFIG_COMPAT_VDSO places the vDSO
49  * in the user address space.
50  */
51 #define VDSO_ADDR_ADJUST        (VDSO_HIGH_BASE - (unsigned long)VDSO32_PRELINK)
52
53 /*
54  * Should the kernel map a VDSO page into processes and pass its
55  * address down to glibc upon exec()?
56  */
57 unsigned int __read_mostly vdso_enabled = VDSO_DEFAULT;
58
59 static int __init vdso_setup(char *s)
60 {
61         vdso_enabled = simple_strtoul(s, NULL, 0);
62
63         return 1;
64 }
65
66 /*
67  * For consistency, the argument vdso32=[012] affects the 32-bit vDSO
68  * behavior on both 64-bit and 32-bit kernels.
69  * On 32-bit kernels, vdso=[012] means the same thing.
70  */
71 __setup("vdso32=", vdso_setup);
72
73 #ifdef CONFIG_X86_32
74 __setup_param("vdso=", vdso32_setup, vdso_setup, 0);
75
76 EXPORT_SYMBOL_GPL(vdso_enabled);
77 #endif
78
79 static __init void reloc_symtab(Elf32_Ehdr *ehdr,
80                                 unsigned offset, unsigned size)
81 {
82         Elf32_Sym *sym = (void *)ehdr + offset;
83         unsigned nsym = size / sizeof(*sym);
84         unsigned i;
85
86         for(i = 0; i < nsym; i++, sym++) {
87                 if (sym->st_shndx == SHN_UNDEF ||
88                     sym->st_shndx == SHN_ABS)
89                         continue;  /* skip */
90
91                 if (sym->st_shndx > SHN_LORESERVE) {
92                         printk(KERN_INFO "VDSO: unexpected st_shndx %x\n",
93                                sym->st_shndx);
94                         continue;
95                 }
96
97                 switch(ELF_ST_TYPE(sym->st_info)) {
98                 case STT_OBJECT:
99                 case STT_FUNC:
100                 case STT_SECTION:
101                 case STT_FILE:
102                         sym->st_value += VDSO_ADDR_ADJUST;
103                 }
104         }
105 }
106
107 static __init void reloc_dyn(Elf32_Ehdr *ehdr, unsigned offset)
108 {
109         Elf32_Dyn *dyn = (void *)ehdr + offset;
110
111         for(; dyn->d_tag != DT_NULL; dyn++)
112                 switch(dyn->d_tag) {
113                 case DT_PLTGOT:
114                 case DT_HASH:
115                 case DT_STRTAB:
116                 case DT_SYMTAB:
117                 case DT_RELA:
118                 case DT_INIT:
119                 case DT_FINI:
120                 case DT_REL:
121                 case DT_DEBUG:
122                 case DT_JMPREL:
123                 case DT_VERSYM:
124                 case DT_VERDEF:
125                 case DT_VERNEED:
126                 case DT_ADDRRNGLO ... DT_ADDRRNGHI:
127                         /* definitely pointers needing relocation */
128                         dyn->d_un.d_ptr += VDSO_ADDR_ADJUST;
129                         break;
130
131                 case DT_ENCODING ... OLD_DT_LOOS-1:
132                 case DT_LOOS ... DT_HIOS-1:
133                         /* Tags above DT_ENCODING are pointers if
134                            they're even */
135                         if (dyn->d_tag >= DT_ENCODING &&
136                             (dyn->d_tag & 1) == 0)
137                                 dyn->d_un.d_ptr += VDSO_ADDR_ADJUST;
138                         break;
139
140                 case DT_VERDEFNUM:
141                 case DT_VERNEEDNUM:
142                 case DT_FLAGS_1:
143                 case DT_RELACOUNT:
144                 case DT_RELCOUNT:
145                 case DT_VALRNGLO ... DT_VALRNGHI:
146                         /* definitely not pointers */
147                         break;
148
149                 case OLD_DT_LOOS ... DT_LOOS-1:
150                 case DT_HIOS ... DT_VALRNGLO-1:
151                 default:
152                         if (dyn->d_tag > DT_ENCODING)
153                                 printk(KERN_INFO "VDSO: unexpected DT_tag %x\n",
154                                        dyn->d_tag);
155                         break;
156                 }
157 }
158
159 static __init void relocate_vdso(Elf32_Ehdr *ehdr)
160 {
161         Elf32_Phdr *phdr;
162         Elf32_Shdr *shdr;
163         int i;
164
165         BUG_ON(memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0 ||
166                !elf_check_arch_ia32(ehdr) ||
167                ehdr->e_type != ET_DYN);
168
169         ehdr->e_entry += VDSO_ADDR_ADJUST;
170
171         /* rebase phdrs */
172         phdr = (void *)ehdr + ehdr->e_phoff;
173         for (i = 0; i < ehdr->e_phnum; i++) {
174                 phdr[i].p_vaddr += VDSO_ADDR_ADJUST;
175
176                 /* relocate dynamic stuff */
177                 if (phdr[i].p_type == PT_DYNAMIC)
178                         reloc_dyn(ehdr, phdr[i].p_offset);
179         }
180
181         /* rebase sections */
182         shdr = (void *)ehdr + ehdr->e_shoff;
183         for(i = 0; i < ehdr->e_shnum; i++) {
184                 if (!(shdr[i].sh_flags & SHF_ALLOC))
185                         continue;
186
187                 shdr[i].sh_addr += VDSO_ADDR_ADJUST;
188
189                 if (shdr[i].sh_type == SHT_SYMTAB ||
190                     shdr[i].sh_type == SHT_DYNSYM)
191                         reloc_symtab(ehdr, shdr[i].sh_offset,
192                                      shdr[i].sh_size);
193         }
194 }
195
196 /*
197  * These symbols are defined by vdso32.S to mark the bounds
198  * of the ELF DSO images included therein.
199  */
200 extern const char vdso32_default_start, vdso32_default_end;
201 extern const char vdso32_sysenter_start, vdso32_sysenter_end;
202 static struct page *vdso32_pages[1];
203
204 #ifdef CONFIG_X86_64
205
206 #define vdso32_sysenter()       (boot_cpu_has(X86_FEATURE_SYSENTER32))
207
208 /* May not be __init: called during resume */
209 void syscall32_cpu_init(void)
210 {
211         /* Load these always in case some future AMD CPU supports
212            SYSENTER from compat mode too. */
213         checking_wrmsrl(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);
214         checking_wrmsrl(MSR_IA32_SYSENTER_ESP, 0ULL);
215         checking_wrmsrl(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target);
216
217         wrmsrl(MSR_CSTAR, ia32_cstar_target);
218 }
219
220 #define compat_uses_vma         1
221
222 static inline void map_compat_vdso(int map)
223 {
224 }
225
226 #else  /* CONFIG_X86_32 */
227
228 #define vdso32_sysenter()       (boot_cpu_has(X86_FEATURE_SEP))
229
230 void enable_sep_cpu(void)
231 {
232         int cpu = get_cpu();
233         struct tss_struct *tss = &per_cpu(init_tss, cpu);
234
235         if (!boot_cpu_has(X86_FEATURE_SEP)) {
236                 put_cpu();
237                 return;
238         }
239
240         tss->x86_tss.ss1 = __KERNEL_CS;
241         tss->x86_tss.sp1 = sizeof(struct tss_struct) + (unsigned long) tss;
242         wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
243         wrmsr(MSR_IA32_SYSENTER_ESP, tss->x86_tss.sp1, 0);
244         wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) ia32_sysenter_target, 0);
245         put_cpu();      
246 }
247
248 static struct vm_area_struct gate_vma;
249
250 static int __init gate_vma_init(void)
251 {
252         gate_vma.vm_mm = NULL;
253         gate_vma.vm_start = FIXADDR_USER_START;
254         gate_vma.vm_end = FIXADDR_USER_END;
255         gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
256         gate_vma.vm_page_prot = __P101;
257         /*
258          * Make sure the vDSO gets into every core dump.
259          * Dumping its contents makes post-mortem fully interpretable later
260          * without matching up the same kernel and hardware config to see
261          * what PC values meant.
262          */
263         gate_vma.vm_flags |= VM_ALWAYSDUMP;
264         return 0;
265 }
266
267 #define compat_uses_vma         0
268
269 static void map_compat_vdso(int map)
270 {
271         static int vdso_mapped;
272
273         if (map == vdso_mapped)
274                 return;
275
276         vdso_mapped = map;
277
278         __set_fixmap(FIX_VDSO, page_to_pfn(vdso32_pages[0]) << PAGE_SHIFT,
279                      map ? PAGE_READONLY_EXEC : PAGE_NONE);
280
281         /* flush stray tlbs */
282         flush_tlb_all();
283 }
284
285 #endif  /* CONFIG_X86_64 */
286
287 int __init sysenter_setup(void)
288 {
289         void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
290         const void *vsyscall;
291         size_t vsyscall_len;
292
293         vdso32_pages[0] = virt_to_page(syscall_page);
294
295 #ifdef CONFIG_X86_32
296         gate_vma_init();
297 #endif
298
299         if (!vdso32_sysenter()) {
300                 vsyscall = &vdso32_default_start;
301                 vsyscall_len = &vdso32_default_end - &vdso32_default_start;
302         } else {
303                 vsyscall = &vdso32_sysenter_start;
304                 vsyscall_len = &vdso32_sysenter_end - &vdso32_sysenter_start;
305         }
306
307         memcpy(syscall_page, vsyscall, vsyscall_len);
308         relocate_vdso(syscall_page);
309
310         return 0;
311 }
312
313 /* Setup a VMA at program startup for the vsyscall page */
314 int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
315 {
316         struct mm_struct *mm = current->mm;
317         unsigned long addr;
318         int ret = 0;
319         bool compat;
320
321         if (vdso_enabled == VDSO_DISABLED)
322                 return 0;
323
324         down_write(&mm->mmap_sem);
325
326         /* Test compat mode once here, in case someone
327            changes it via sysctl */
328         compat = (vdso_enabled == VDSO_COMPAT);
329
330         map_compat_vdso(compat);
331
332         if (compat)
333                 addr = VDSO_HIGH_BASE;
334         else {
335                 addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
336                 if (IS_ERR_VALUE(addr)) {
337                         ret = addr;
338                         goto up_fail;
339                 }
340         }
341
342         if (compat_uses_vma || !compat) {
343                 /*
344                  * MAYWRITE to allow gdb to COW and set breakpoints
345                  *
346                  * Make sure the vDSO gets into every core dump.
347                  * Dumping its contents makes post-mortem fully
348                  * interpretable later without matching up the same
349                  * kernel and hardware config to see what PC values
350                  * meant.
351                  */
352                 ret = install_special_mapping(mm, addr, PAGE_SIZE,
353                                               VM_READ|VM_EXEC|
354                                               VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
355                                               VM_ALWAYSDUMP,
356                                               vdso32_pages);
357
358                 if (ret)
359                         goto up_fail;
360         }
361
362         current->mm->context.vdso = (void *)addr;
363         current_thread_info()->sysenter_return =
364                 VDSO32_SYMBOL(addr, SYSENTER_RETURN);
365
366   up_fail:
367         up_write(&mm->mmap_sem);
368
369         return ret;
370 }
371
372 #ifdef CONFIG_X86_64
373
374 __initcall(sysenter_setup);
375
376 #ifdef CONFIG_SYSCTL
377 /* Register vsyscall32 into the ABI table */
378 #include <linux/sysctl.h>
379
380 static ctl_table abi_table2[] = {
381         {
382                 .procname       = "vsyscall32",
383                 .data           = &sysctl_vsyscall32,
384                 .maxlen         = sizeof(int),
385                 .mode           = 0644,
386                 .proc_handler   = proc_dointvec
387         },
388         {}
389 };
390
391 static ctl_table abi_root_table2[] = {
392         {
393                 .ctl_name = CTL_ABI,
394                 .procname = "abi",
395                 .mode = 0555,
396                 .child = abi_table2
397         },
398         {}
399 };
400
401 static __init int ia32_binfmt_init(void)
402 {
403         register_sysctl_table(abi_root_table2);
404         return 0;
405 }
406 __initcall(ia32_binfmt_init);
407 #endif
408
409 #else  /* CONFIG_X86_32 */
410
411 const char *arch_vma_name(struct vm_area_struct *vma)
412 {
413         if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
414                 return "[vdso]";
415         return NULL;
416 }
417
418 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
419 {
420         struct mm_struct *mm = tsk->mm;
421
422         /* Check to see if this task was created in compat vdso mode */
423         if (mm && mm->context.vdso == (void *)VDSO_HIGH_BASE)
424                 return &gate_vma;
425         return NULL;
426 }
427
428 int in_gate_area(struct task_struct *task, unsigned long addr)
429 {
430         const struct vm_area_struct *vma = get_gate_vma(task);
431
432         return vma && addr >= vma->vm_start && addr < vma->vm_end;
433 }
434
435 int in_gate_area_no_task(unsigned long addr)
436 {
437         return 0;
438 }
439
440 #endif  /* CONFIG_X86_64 */