/*

   * (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 <linux/slab.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>

  #include <asm/fixmap.h>
  #include <asm/hpet.h>
  #include <asm/vvar.h>

  #ifdef CONFIG_COMPAT_VDSO

  #define VDSO_DEFAULT	0

  #else

  #define VDSO_DEFAULT	1

  #endif

  #ifdef CONFIG_X86_64
  #define vdso_enabled			sysctl_vsyscall32
  #define arch_setup_additional_pages	syscall32_setup_pages

  extern int sysctl_ldt16;

  #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;

  static int __init vdso_setup(char *s)
  {
  	vdso_enabled = simple_strtoul(s, NULL, 0);

  	if (vdso_enabled > 1)
  		pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled
  ");

  	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 struct page **vdso32_pages;

  static unsigned vdso32_size;

  
  #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);
  }

  #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();	
  }

  #endif	/* CONFIG_X86_64 */

  int __init sysenter_setup(void)

  {

  	char *vdso32_start, *vdso32_end;
  	int npages, i;

  #ifdef CONFIG_COMPAT

  	if (vdso32_syscall()) {

  		vdso32_start = vdso32_syscall_start;
  		vdso32_end = vdso32_syscall_end;
  		vdso32_pages = vdso32_syscall_pages;
  	} else
  #endif
  	if (vdso32_sysenter()) {
  		vdso32_start = vdso32_sysenter_start;
  		vdso32_end = vdso32_sysenter_end;
  		vdso32_pages = vdso32_sysenter_pages;

  	} else {

  		vdso32_start = vdso32_int80_start;
  		vdso32_end = vdso32_int80_end;
  		vdso32_pages = vdso32_int80_pages;

  	}

  	npages = ((vdso32_end - vdso32_start) + PAGE_SIZE - 1) / PAGE_SIZE;
  	vdso32_size = npages << PAGE_SHIFT;
  	for (i = 0; i < npages; i++)
  		vdso32_pages[i] = virt_to_page(vdso32_start + i*PAGE_SIZE);

  	patch_vdso32(vdso32_start, vdso32_size);

  	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;

  	struct vm_area_struct *vma;

  	static struct page *no_pages[] = {NULL};

  #ifdef CONFIG_X86_X32_ABI

  	if (test_thread_flag(TIF_X32))

  		return x32_setup_additional_pages(bprm, uses_interp);

  #endif

  	if (vdso_enabled != 1)  /* Other values all mean "disabled" */

  		return 0;

  	down_write(&mm->mmap_sem);

  	addr = get_unmapped_area(NULL, 0, vdso32_size + VDSO_OFFSET(VDSO_PREV_PAGES), 0, 0);

  	if (IS_ERR_VALUE(addr)) {
  		ret = addr;
  		goto up_fail;

  	}

  	addr += VDSO_OFFSET(VDSO_PREV_PAGES);

  	current->mm->context.vdso = (void *)addr;

  	/*
  	 * MAYWRITE to allow gdb to COW and set breakpoints
  	 */

  	ret = install_special_mapping(mm,
  			addr,

  			vdso32_size,

  			VM_READ|VM_EXEC|
  			VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
  			vdso32_pages);

  
  	if (ret)
  		goto up_fail;

  	vma = _install_special_mapping(mm,
  			addr -  VDSO_OFFSET(VDSO_PREV_PAGES),
  			VDSO_OFFSET(VDSO_PREV_PAGES),
  			VM_READ,

  			no_pages);

  
  	if (IS_ERR(vma)) {
  		ret = PTR_ERR(vma);
  		goto up_fail;
  	}
  
  	ret = remap_pfn_range(vma,
  		addr - VDSO_OFFSET(VDSO_VVAR_PAGE),
  		__pa_symbol(&__vvar_page) >> PAGE_SHIFT,
  		PAGE_SIZE,
  		PAGE_READONLY);
  
  	if (ret)
  		goto up_fail;
  
  #ifdef CONFIG_HPET_TIMER
  	if (hpet_address) {
  		ret = io_remap_pfn_range(vma,
  			addr - VDSO_OFFSET(VDSO_HPET_PAGE),
  			hpet_address >> PAGE_SHIFT,
  			PAGE_SIZE,
  			pgprot_noncached(PAGE_READONLY));
  
  		if (ret)
  			goto up_fail;
  	}
  #endif

  	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 struct ctl_table abi_table2[] = {

  	{
  		.procname	= "vsyscall32",
  		.data		= &sysctl_vsyscall32,
  		.maxlen		= sizeof(int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec
  	},

  	{
  		.procname	= "ldt16",
  		.data		= &sysctl_ldt16,
  		.maxlen		= sizeof(int),
  		.mode		= 0644,
  		.proc_handler	= proc_dointvec
  	},

  	{}
  };

  static struct 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)

  {
  	return NULL;
  }

  int in_gate_area(struct mm_struct *mm, unsigned long addr)

  {

  	return 0;

  }

  int in_gate_area_no_mm(unsigned long addr)

  {
  	return 0;
  }

  
  #endif	/* CONFIG_X86_64 */