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/*
* linux/arch/i386/kernel/sysenter.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/module.h>
#include <asm/cpufeature.h>
#include <asm/msr.h>
#include <asm/pgtable.h>
#include <asm/unistd.h>
/*
* Should the kernel map a VDSO page into processes and pass its
* address down to glibc upon exec()?
*/
#ifdef CONFIG_PARAVIRT
unsigned int __read_mostly vdso_enabled = 0;
#else
unsigned int __read_mostly vdso_enabled = 1;
#endif
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);
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->ss1 = __KERNEL_CS;
tss->esp1 = sizeof(struct tss_struct) + (unsigned long) tss;
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
wrmsr(MSR_IA32_SYSENTER_ESP, tss->esp1, 0);
wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) sysenter_entry, 0);
put_cpu();
}
/*
* 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];
int __init sysenter_setup(void)
{
void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
syscall_pages[0] = virt_to_page(syscall_page);
#ifdef CONFIG_COMPAT_VDSO
__set_fixmap(FIX_VDSO, __pa(syscall_page), PAGE_READONLY);
printk("Compat vDSO mapped to %08lx.\n", __fix_to_virt(FIX_VDSO));
#endif
if (!boot_cpu_has(X86_FEATURE_SEP)) {
memcpy(syscall_page,
&vsyscall_int80_start,
&vsyscall_int80_end - &vsyscall_int80_start);
return 0;
}
memcpy(syscall_page,
&vsyscall_sysenter_start,
&vsyscall_sysenter_end - &vsyscall_sysenter_start);
return 0;
}
#ifndef CONFIG_COMPAT_VDSO
/* 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;
down_write(&mm->mmap_sem);
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)
{
return NULL;
}
int in_gate_area(struct task_struct *task, unsigned long addr)
{
return 0;
}
int in_gate_area_no_task(unsigned long addr)
{
return 0;
}
#endif
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