Loading...
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 | /*
* (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>
enum {
VDSO_DISABLED = 0,
VDSO_ENABLED = 1,
VDSO_COMPAT = 2,
};
#ifdef CONFIG_COMPAT_VDSO
#define VDSO_DEFAULT VDSO_COMPAT
#else
#define VDSO_DEFAULT VDSO_ENABLED
#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;
EXPORT_SYMBOL_GPL(vdso_enabled);
static int __init vdso_setup(char *s)
{
vdso_enabled = simple_strtoul(s, NULL, 0);
return 1;
}
__setup("vdso=", vdso_setup);
extern asmlinkage void sysenter_entry(void);
static __init void reloc_symtab(Elf32_Ehdr *ehdr,
unsigned offset, unsigned size)
{
Elf32_Sym *sym = (void *)ehdr + offset;
unsigned nsym = size / sizeof(*sym);
unsigned i;
for(i = 0; i < nsym; i++, sym++) {
if (sym->st_shndx == SHN_UNDEF ||
sym->st_shndx == SHN_ABS)
continue; /* skip */
if (sym->st_shndx > SHN_LORESERVE) {
printk(KERN_INFO "VDSO: unexpected st_shndx %x\n",
sym->st_shndx);
continue;
}
switch(ELF_ST_TYPE(sym->st_info)) {
case STT_OBJECT:
case STT_FUNC:
case STT_SECTION:
case STT_FILE:
sym->st_value += VDSO_HIGH_BASE;
}
}
}
static __init void reloc_dyn(Elf32_Ehdr *ehdr, unsigned offset)
{
Elf32_Dyn *dyn = (void *)ehdr + offset;
for(; dyn->d_tag != DT_NULL; dyn++)
switch(dyn->d_tag) {
case DT_PLTGOT:
case DT_HASH:
case DT_STRTAB:
case DT_SYMTAB:
case DT_RELA:
case DT_INIT:
case DT_FINI:
case DT_REL:
case DT_DEBUG:
case DT_JMPREL:
case DT_VERSYM:
case DT_VERDEF:
case DT_VERNEED:
case DT_ADDRRNGLO ... DT_ADDRRNGHI:
/* definitely pointers needing relocation */
dyn->d_un.d_ptr += VDSO_HIGH_BASE;
break;
case DT_ENCODING ... OLD_DT_LOOS-1:
case DT_LOOS ... DT_HIOS-1:
/* Tags above DT_ENCODING are pointers if
they're even */
if (dyn->d_tag >= DT_ENCODING &&
(dyn->d_tag & 1) == 0)
dyn->d_un.d_ptr += VDSO_HIGH_BASE;
break;
case DT_VERDEFNUM:
case DT_VERNEEDNUM:
case DT_FLAGS_1:
case DT_RELACOUNT:
case DT_RELCOUNT:
case DT_VALRNGLO ... DT_VALRNGHI:
/* definitely not pointers */
break;
case OLD_DT_LOOS ... DT_LOOS-1:
case DT_HIOS ... DT_VALRNGLO-1:
default:
if (dyn->d_tag > DT_ENCODING)
printk(KERN_INFO "VDSO: unexpected DT_tag %x\n",
dyn->d_tag);
break;
}
}
static __init void relocate_vdso(Elf32_Ehdr *ehdr)
{
Elf32_Phdr *phdr;
Elf32_Shdr *shdr;
int i;
BUG_ON(memcmp(ehdr->e_ident, ELFMAG, 4) != 0 ||
!elf_check_arch(ehdr) ||
ehdr->e_type != ET_DYN);
ehdr->e_entry += VDSO_HIGH_BASE;
/* rebase phdrs */
phdr = (void *)ehdr + ehdr->e_phoff;
for (i = 0; i < ehdr->e_phnum; i++) {
phdr[i].p_vaddr += VDSO_HIGH_BASE;
/* relocate dynamic stuff */
if (phdr[i].p_type == PT_DYNAMIC)
reloc_dyn(ehdr, phdr[i].p_offset);
}
/* rebase sections */
shdr = (void *)ehdr + ehdr->e_shoff;
for(i = 0; i < ehdr->e_shnum; i++) {
if (!(shdr[i].sh_flags & SHF_ALLOC))
continue;
shdr[i].sh_addr += VDSO_HIGH_BASE;
if (shdr[i].sh_type == SHT_SYMTAB ||
shdr[i].sh_type == SHT_DYNSYM)
reloc_symtab(ehdr, shdr[i].sh_offset,
shdr[i].sh_size);
}
}
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.esp1 = sizeof(struct tss_struct) + (unsigned long) tss;
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
wrmsr(MSR_IA32_SYSENTER_ESP, tss->x86_tss.esp1, 0);
wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) sysenter_entry, 0);
put_cpu();
}
static struct vm_area_struct gate_vma;
static int __init gate_vma_init(void)
{
gate_vma.vm_mm = NULL;
gate_vma.vm_start = FIXADDR_USER_START;
gate_vma.vm_end = FIXADDR_USER_END;
gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
gate_vma.vm_page_prot = __P101;
/*
* Make sure the vDSO gets into every core dump.
* Dumping its contents makes post-mortem fully interpretable later
* without matching up the same kernel and hardware config to see
* what PC values meant.
*/
gate_vma.vm_flags |= VM_ALWAYSDUMP;
return 0;
}
/*
* These symbols are defined by vsyscall.o to mark the bounds
* of the ELF DSO images included therein.
*/
extern const char vsyscall_int80_start, vsyscall_int80_end;
extern const char vsyscall_sysenter_start, vsyscall_sysenter_end;
static struct page *syscall_pages[1];
static void map_compat_vdso(int map)
{
static int vdso_mapped;
if (map == vdso_mapped)
return;
vdso_mapped = map;
__set_fixmap(FIX_VDSO, page_to_pfn(syscall_pages[0]) << PAGE_SHIFT,
map ? PAGE_READONLY_EXEC : PAGE_NONE);
/* flush stray tlbs */
flush_tlb_all();
}
int __init sysenter_setup(void)
{
void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
const void *vsyscall;
size_t vsyscall_len;
syscall_pages[0] = virt_to_page(syscall_page);
gate_vma_init();
printk("Compat vDSO mapped to %08lx.\n", __fix_to_virt(FIX_VDSO));
if (!boot_cpu_has(X86_FEATURE_SEP)) {
vsyscall = &vsyscall_int80_start;
vsyscall_len = &vsyscall_int80_end - &vsyscall_int80_start;
} else {
vsyscall = &vsyscall_sysenter_start;
vsyscall_len = &vsyscall_sysenter_end - &vsyscall_sysenter_start;
}
memcpy(syscall_page, vsyscall, vsyscall_len);
relocate_vdso(syscall_page);
return 0;
}
/* Defined in vsyscall-sysenter.S */
extern void SYSENTER_RETURN;
/* Setup a VMA at program startup for the vsyscall page */
int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
{
struct mm_struct *mm = current->mm;
unsigned long addr;
int ret = 0;
bool compat;
down_write(&mm->mmap_sem);
/* Test compat mode once here, in case someone
changes it via sysctl */
compat = (vdso_enabled == VDSO_COMPAT);
map_compat_vdso(compat);
if (compat)
addr = VDSO_HIGH_BASE;
else {
addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
if (IS_ERR_VALUE(addr)) {
ret = addr;
goto up_fail;
}
/*
* MAYWRITE to allow gdb to COW and set breakpoints
*
* Make sure the vDSO gets into every core dump.
* Dumping its contents makes post-mortem fully
* interpretable later without matching up the same
* kernel and hardware config to see what PC values
* meant.
*/
ret = install_special_mapping(mm, addr, PAGE_SIZE,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
VM_ALWAYSDUMP,
syscall_pages);
if (ret)
goto up_fail;
}
current->mm->context.vdso = (void *)addr;
current_thread_info()->sysenter_return =
(void *)VDSO_SYM(&SYSENTER_RETURN);
up_fail:
up_write(&mm->mmap_sem);
return ret;
}
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 task_struct *tsk)
{
struct mm_struct *mm = tsk->mm;
/* Check to see if this task was created in compat vdso mode */
if (mm && mm->context.vdso == (void *)VDSO_HIGH_BASE)
return &gate_vma;
return NULL;
}
int in_gate_area(struct task_struct *task, unsigned long addr)
{
const struct vm_area_struct *vma = get_gate_vma(task);
return vma && addr >= vma->vm_start && addr < vma->vm_end;
}
int in_gate_area_no_task(unsigned long addr)
{
return 0;
}
|