arch/x86/vdso/vdso32-setup.c - maze/linux - Git at Google

 /*
  * (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
 #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\n");

 	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;

 #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,
 			NULL);

 	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
 	},
 	{}
 };

 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 */
	/*
	* (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
	#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\n");

	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;

	#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,
	NULL);

	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
	},
	{}
	};

	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 */