436 lines
9.3 KiB
C
436 lines
9.3 KiB
C
/*
|
|
* (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>
|
|
|
|
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
|
|
|
|
#ifdef CONFIG_X86_64
|
|
#define vdso_enabled sysctl_vsyscall32
|
|
#define arch_setup_additional_pages syscall32_setup_pages
|
|
#endif
|
|
|
|
/*
|
|
* This is the difference between the prelinked addresses in the vDSO images
|
|
* and the VDSO_HIGH_BASE address where CONFIG_COMPAT_VDSO places the vDSO
|
|
* in the user address space.
|
|
*/
|
|
#define VDSO_ADDR_ADJUST (VDSO_HIGH_BASE - (unsigned long)VDSO32_PRELINK)
|
|
|
|
/*
|
|
* 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);
|
|
|
|
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 __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_ADDR_ADJUST;
|
|
}
|
|
}
|
|
}
|
|
|
|
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_ADDR_ADJUST;
|
|
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_ADDR_ADJUST;
|
|
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, SELFMAG) != 0 ||
|
|
!elf_check_arch_ia32(ehdr) ||
|
|
ehdr->e_type != ET_DYN);
|
|
|
|
ehdr->e_entry += VDSO_ADDR_ADJUST;
|
|
|
|
/* rebase phdrs */
|
|
phdr = (void *)ehdr + ehdr->e_phoff;
|
|
for (i = 0; i < ehdr->e_phnum; i++) {
|
|
phdr[i].p_vaddr += VDSO_ADDR_ADJUST;
|
|
|
|
/* 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_ADDR_ADJUST;
|
|
|
|
if (shdr[i].sh_type == SHT_SYMTAB ||
|
|
shdr[i].sh_type == SHT_DYNSYM)
|
|
reloc_symtab(ehdr, shdr[i].sh_offset,
|
|
shdr[i].sh_size);
|
|
}
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
#define compat_uses_vma 1
|
|
|
|
static inline void map_compat_vdso(int map)
|
|
{
|
|
}
|
|
|
|
#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();
|
|
}
|
|
|
|
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;
|
|
|
|
return 0;
|
|
}
|
|
|
|
#define compat_uses_vma 0
|
|
|
|
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(vdso32_pages[0]) << PAGE_SHIFT,
|
|
map ? PAGE_READONLY_EXEC : PAGE_NONE);
|
|
|
|
/* flush stray tlbs */
|
|
flush_tlb_all();
|
|
}
|
|
|
|
#endif /* CONFIG_X86_64 */
|
|
|
|
int __init sysenter_setup(void)
|
|
{
|
|
void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
|
|
const void *vsyscall;
|
|
size_t vsyscall_len;
|
|
|
|
vdso32_pages[0] = virt_to_page(syscall_page);
|
|
|
|
#ifdef CONFIG_X86_32
|
|
gate_vma_init();
|
|
#endif
|
|
|
|
if (vdso32_syscall()) {
|
|
vsyscall = &vdso32_syscall_start;
|
|
vsyscall_len = &vdso32_syscall_end - &vdso32_syscall_start;
|
|
} else if (vdso32_sysenter()){
|
|
vsyscall = &vdso32_sysenter_start;
|
|
vsyscall_len = &vdso32_sysenter_end - &vdso32_sysenter_start;
|
|
} else {
|
|
vsyscall = &vdso32_int80_start;
|
|
vsyscall_len = &vdso32_int80_end - &vdso32_int80_start;
|
|
}
|
|
|
|
memcpy(syscall_page, vsyscall, vsyscall_len);
|
|
relocate_vdso(syscall_page);
|
|
|
|
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;
|
|
bool compat;
|
|
|
|
#ifdef CONFIG_X86_X32_ABI
|
|
if (test_thread_flag(TIF_X32))
|
|
return x32_setup_additional_pages(bprm, uses_interp);
|
|
#endif
|
|
|
|
if (vdso_enabled == VDSO_DISABLED)
|
|
return 0;
|
|
|
|
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;
|
|
}
|
|
}
|
|
|
|
current->mm->context.vdso = (void *)addr;
|
|
|
|
if (compat_uses_vma || !compat) {
|
|
/*
|
|
* 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 ctl_table abi_table2[] = {
|
|
{
|
|
.procname = "vsyscall32",
|
|
.data = &sysctl_vsyscall32,
|
|
.maxlen = sizeof(int),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dointvec
|
|
},
|
|
{}
|
|
};
|
|
|
|
static 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)
|
|
{
|
|
/*
|
|
* Check to see if the corresponding 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 mm_struct *mm, unsigned long addr)
|
|
{
|
|
const struct vm_area_struct *vma = get_gate_vma(mm);
|
|
|
|
return vma && addr >= vma->vm_start && addr < vma->vm_end;
|
|
}
|
|
|
|
int in_gate_area_no_mm(unsigned long addr)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
#endif /* CONFIG_X86_64 */
|