[mirror_ubuntu-focal-kernel.git] / arch / x86 / entry / vdso / vma.c

/*
 * Copyright 2007 Andi Kleen, SUSE Labs.
 * Subject to the GPL, v.2
 *
 * This contains most of the x86 vDSO kernel-side code.
 */
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/random.h>
#include <linux/elf.h>
#include <linux/cpu.h>
#include <linux/ptrace.h>
#include <asm/pvclock.h>
#include <asm/vgtod.h>
#include <asm/proto.h>
#include <asm/vdso.h>
#include <asm/vvar.h>
#include <asm/page.h>
#include <asm/desc.h>
#include <asm/cpufeature.h>

#if defined(CONFIG_X86_64)
unsigned int __read_mostly vdso64_enabled = 1;
#endif

void __init init_vdso_image(const struct vdso_image *image)
{
	BUG_ON(image->size % PAGE_SIZE != 0);

	apply_alternatives((struct alt_instr *)(image->data + image->alt),
			   (struct alt_instr *)(image->data + image->alt +
						image->alt_len));
}

struct linux_binprm;

static int vdso_fault(const struct vm_special_mapping *sm,
		      struct vm_area_struct *vma, struct vm_fault *vmf)
{
	const struct vdso_image *image = vma->vm_mm->context.vdso_image;

	if (!image || (vmf->pgoff << PAGE_SHIFT) >= image->size)
		return VM_FAULT_SIGBUS;

	vmf->page = virt_to_page(image->data + (vmf->pgoff << PAGE_SHIFT));
	get_page(vmf->page);
	return 0;
}

static void vdso_fix_landing(const struct vdso_image *image,
		struct vm_area_struct *new_vma)
{
#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
	if (in_ia32_syscall() && image == &vdso_image_32) {
		struct pt_regs *regs = current_pt_regs();
		unsigned long vdso_land = image->sym_int80_landing_pad;
		unsigned long old_land_addr = vdso_land +
			(unsigned long)current->mm->context.vdso;

		/* Fixing userspace landing - look at do_fast_syscall_32 */
		if (regs->ip == old_land_addr)
			regs->ip = new_vma->vm_start + vdso_land;
	}
#endif
}

static int vdso_mremap(const struct vm_special_mapping *sm,
		struct vm_area_struct *new_vma)
{
	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
	const struct vdso_image *image = current->mm->context.vdso_image;

	if (image->size != new_size)
		return -EINVAL;

	if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
		return -EFAULT;

	vdso_fix_landing(image, new_vma);
	current->mm->context.vdso = (void __user *)new_vma->vm_start;

	return 0;
}

static int vvar_fault(const struct vm_special_mapping *sm,
		      struct vm_area_struct *vma, struct vm_fault *vmf)
{
	const struct vdso_image *image = vma->vm_mm->context.vdso_image;
	long sym_offset;
	int ret = -EFAULT;

	if (!image)
		return VM_FAULT_SIGBUS;

	sym_offset = (long)(vmf->pgoff << PAGE_SHIFT) +
		image->sym_vvar_start;

	/*
	 * Sanity check: a symbol offset of zero means that the page
	 * does not exist for this vdso image, not that the page is at
	 * offset zero relative to the text mapping.  This should be
	 * impossible here, because sym_offset should only be zero for
	 * the page past the end of the vvar mapping.
	 */
	if (sym_offset == 0)
		return VM_FAULT_SIGBUS;

	if (sym_offset == image->sym_vvar_page) {
		ret = vm_insert_pfn(vma, vmf->address,
				    __pa_symbol(&__vvar_page) >> PAGE_SHIFT);
	} else if (sym_offset == image->sym_pvclock_page) {
		struct pvclock_vsyscall_time_info *pvti =
			pvclock_pvti_cpu0_va();
		if (pvti && vclock_was_used(VCLOCK_PVCLOCK)) {
			ret = vm_insert_pfn(
				vma,
				vmf->address,
				__pa(pvti) >> PAGE_SHIFT);
		}
	}

	if (ret == 0 || ret == -EBUSY)
		return VM_FAULT_NOPAGE;

	return VM_FAULT_SIGBUS;
}

static const struct vm_special_mapping vdso_mapping = {
	.name = "[vdso]",
	.fault = vdso_fault,
	.mremap = vdso_mremap,
};
static const struct vm_special_mapping vvar_mapping = {
	.name = "[vvar]",
	.fault = vvar_fault,
};

/*
 * Add vdso and vvar mappings to current process.
 * @image          - blob to map
 * @addr           - request a specific address (zero to map at free addr)
 */
static int map_vdso(const struct vdso_image *image, unsigned long addr)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned long text_start;
	int ret = 0;

	if (down_write_killable(&mm->mmap_sem))
		return -EINTR;

	addr = get_unmapped_area(NULL, addr,
				 image->size - image->sym_vvar_start, 0, 0);
	if (IS_ERR_VALUE(addr)) {
		ret = addr;
		goto up_fail;
	}

	text_start = addr - image->sym_vvar_start;

	/*
	 * MAYWRITE to allow gdb to COW and set breakpoints
	 */
	vma = _install_special_mapping(mm,
				       text_start,
				       image->size,
				       VM_READ|VM_EXEC|
				       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
				       &vdso_mapping);

	if (IS_ERR(vma)) {
		ret = PTR_ERR(vma);
		goto up_fail;
	}

	vma = _install_special_mapping(mm,
				       addr,
				       -image->sym_vvar_start,
				       VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
				       VM_PFNMAP,
				       &vvar_mapping);

	if (IS_ERR(vma)) {
		ret = PTR_ERR(vma);
		do_munmap(mm, text_start, image->size, NULL);
	} else {
		current->mm->context.vdso = (void __user *)text_start;
		current->mm->context.vdso_image = image;
	}

up_fail:
	up_write(&mm->mmap_sem);
	return ret;
}

#ifdef CONFIG_X86_64
/*
 * Put the vdso above the (randomized) stack with another randomized
 * offset.  This way there is no hole in the middle of address space.
 * To save memory make sure it is still in the same PTE as the stack
 * top.  This doesn't give that many random bits.
 *
 * Note that this algorithm is imperfect: the distribution of the vdso
 * start address within a PMD is biased toward the end.
 *
 * Only used for the 64-bit and x32 vdsos.
 */
static unsigned long vdso_addr(unsigned long start, unsigned len)
{
	unsigned long addr, end;
	unsigned offset;

	/*
	 * Round up the start address.  It can start out unaligned as a result
	 * of stack start randomization.
	 */
	start = PAGE_ALIGN(start);

	/* Round the lowest possible end address up to a PMD boundary. */
	end = (start + len + PMD_SIZE - 1) & PMD_MASK;
	if (end >= TASK_SIZE_MAX)
		end = TASK_SIZE_MAX;
	end -= len;

	if (end > start) {
		offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);
		addr = start + (offset << PAGE_SHIFT);
	} else {
		addr = start;
	}

	/*
	 * Forcibly align the final address in case we have a hardware
	 * issue that requires alignment for performance reasons.
	 */
	addr = align_vdso_addr(addr);

	return addr;
}

static int map_vdso_randomized(const struct vdso_image *image)
{
	unsigned long addr = vdso_addr(current->mm->start_stack, image->size-image->sym_vvar_start);

	return map_vdso(image, addr);
}
#endif

int map_vdso_once(const struct vdso_image *image, unsigned long addr)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;

	down_write(&mm->mmap_sem);
	/*
	 * Check if we have already mapped vdso blob - fail to prevent
	 * abusing from userspace install_speciall_mapping, which may
	 * not do accounting and rlimit right.
	 * We could search vma near context.vdso, but it's a slowpath,
	 * so let's explicitely check all VMAs to be completely sure.
	 */
	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (vma_is_special_mapping(vma, &vdso_mapping) ||
				vma_is_special_mapping(vma, &vvar_mapping)) {
			up_write(&mm->mmap_sem);
			return -EEXIST;
		}
	}
	up_write(&mm->mmap_sem);

	return map_vdso(image, addr);
}

#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
static int load_vdso32(void)
{
	if (vdso32_enabled != 1)  /* Other values all mean "disabled" */
		return 0;

	return map_vdso(&vdso_image_32, 0);
}
#endif

#ifdef CONFIG_X86_64
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
	if (!vdso64_enabled)
		return 0;

	return map_vdso_randomized(&vdso_image_64);
}

#ifdef CONFIG_COMPAT
int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
				       int uses_interp)
{
#ifdef CONFIG_X86_X32_ABI
	if (test_thread_flag(TIF_X32)) {
		if (!vdso64_enabled)
			return 0;
		return map_vdso_randomized(&vdso_image_x32);
	}
#endif
#ifdef CONFIG_IA32_EMULATION
	return load_vdso32();
#else
	return 0;
#endif
}
#endif
#else
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
	return load_vdso32();
}
#endif

#ifdef CONFIG_X86_64
static __init int vdso_setup(char *s)
{
	vdso64_enabled = simple_strtoul(s, NULL, 0);
	return 0;
}
__setup("vdso=", vdso_setup);
#endif

#ifdef CONFIG_X86_64
static void vgetcpu_cpu_init(void *arg)
{
	int cpu = smp_processor_id();
	struct desc_struct d = { };
	unsigned long node = 0;
#ifdef CONFIG_NUMA
	node = cpu_to_node(cpu);
#endif
	if (static_cpu_has(X86_FEATURE_RDTSCP))
		write_rdtscp_aux((node << 12) | cpu);

	/*
	 * Store cpu number in limit so that it can be loaded
	 * quickly in user space in vgetcpu. (12 bits for the CPU
	 * and 8 bits for the node)
	 */
	d.limit0 = cpu | ((node & 0xf) << 12);
	d.limit = node >> 4;
	d.type = 5;		/* RO data, expand down, accessed */
	d.dpl = 3;		/* Visible to user code */
	d.s = 1;		/* Not a system segment */
	d.p = 1;		/* Present */
	d.d = 1;		/* 32-bit */

	write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);
}

static int vgetcpu_online(unsigned int cpu)
{
	return smp_call_function_single(cpu, vgetcpu_cpu_init, NULL, 1);
}

static int __init init_vdso(void)
{
	init_vdso_image(&vdso_image_64);

#ifdef CONFIG_X86_X32_ABI
	init_vdso_image(&vdso_image_x32);
#endif

	/* notifier priority > KVM */
	return cpuhp_setup_state(CPUHP_AP_X86_VDSO_VMA_ONLINE,
				 "x86/vdso/vma:online", vgetcpu_online, NULL);
}
subsys_initcall(init_vdso);
#endif /* CONFIG_X86_64 */
Commit	Line	Data
2aae950b	1	/*
2aae950b AK	2	* Copyright 2007 Andi Kleen, SUSE Labs.
2aae950b AK	3	* Subject to the GPL, v.2
1c0c1b93 AL	4	*
1c0c1b93 AL	5	* This contains most of the x86 vDSO kernel-side code.
2aae950b AK	6	*/
2aae950b AK	7	#include <linux/mm.h>
4e950f6f	8	#include <linux/err.h>
2aae950b	9	#include <linux/sched.h>
68db0cf1	10	#include <linux/sched/task_stack.h>
5a0e3ad6	11	#include <linux/slab.h>
2aae950b AK	12	#include <linux/init.h>
2aae950b AK	13	#include <linux/random.h>
3fa89ca7	14	#include <linux/elf.h>
d4f829dd	15	#include <linux/cpu.h>
b059a453	16	#include <linux/ptrace.h>
cc1e24fd	17	#include <asm/pvclock.h>
2aae950b AK	18	#include <asm/vgtod.h>
2aae950b AK	19	#include <asm/proto.h>
7f3646aa	20	#include <asm/vdso.h>
1c0c1b93	21	#include <asm/vvar.h>
aafade24	22	#include <asm/page.h>
d4f829dd	23	#include <asm/desc.h>
cd4d09ec	24	#include <asm/cpufeature.h>
2aae950b	25
b4b541a6	26	#if defined(CONFIG_X86_64)
3d7ee969	27	unsigned int __read_mostly vdso64_enabled = 1;
b4b541a6	28	#endif
1a21d4e0	29
6f121e54	30	void __init init_vdso_image(const struct vdso_image *image)
1a21d4e0	31	{
6f121e54	32	BUG_ON(image->size % PAGE_SIZE != 0);
1a21d4e0	33
6f121e54 AL	34	apply_alternatives((struct alt_instr *)(image->data + image->alt),
	35	(struct alt_instr *)(image->data + image->alt +
	36	image->alt_len));
1a21d4e0	37	}
1b3f2a72	38
2aae950b AK	39	struct linux_binprm;
2aae950b AK	40
05ef76b2 AL	41	static int vdso_fault(const struct vm_special_mapping *sm,
	42	struct vm_area_struct vma, struct vm_fault vmf)
	43	{
	44	const struct vdso_image *image = vma->vm_mm->context.vdso_image;
	45
	46	if (!image \|\| (vmf->pgoff << PAGE_SHIFT) >= image->size)
	47	return VM_FAULT_SIGBUS;
	48
	49	vmf->page = virt_to_page(image->data + (vmf->pgoff << PAGE_SHIFT));
	50	get_page(vmf->page);
	51	return 0;
	52	}
	53
b059a453 DS	54	static void vdso_fix_landing(const struct vdso_image *image,
	55	struct vm_area_struct *new_vma)
	56	{
	57	#if defined CONFIG_X86_32 \|\| defined CONFIG_IA32_EMULATION
	58	if (in_ia32_syscall() && image == &vdso_image_32) {
	59	struct pt_regs *regs = current_pt_regs();
	60	unsigned long vdso_land = image->sym_int80_landing_pad;
	61	unsigned long old_land_addr = vdso_land +
	62	(unsigned long)current->mm->context.vdso;
	63
	64	/* Fixing userspace landing - look at do_fast_syscall_32 */
	65	if (regs->ip == old_land_addr)
	66	regs->ip = new_vma->vm_start + vdso_land;
	67	}
	68	#endif
	69	}
	70
	71	static int vdso_mremap(const struct vm_special_mapping *sm,
	72	struct vm_area_struct *new_vma)
	73	{
	74	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
	75	const struct vdso_image *image = current->mm->context.vdso_image;
	76
	77	if (image->size != new_size)
	78	return -EINVAL;
	79
	80	if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
	81	return -EFAULT;
	82
	83	vdso_fix_landing(image, new_vma);
	84	current->mm->context.vdso = (void __user *)new_vma->vm_start;
	85
	86	return 0;
	87	}
05ef76b2	88
a48a7042 AL	89	static int vvar_fault(const struct vm_special_mapping *sm,
	90	struct vm_area_struct vma, struct vm_fault vmf)
	91	{
	92	const struct vdso_image *image = vma->vm_mm->context.vdso_image;
	93	long sym_offset;
	94	int ret = -EFAULT;
	95
	96	if (!image)
	97	return VM_FAULT_SIGBUS;
	98
	99	sym_offset = (long)(vmf->pgoff << PAGE_SHIFT) +
	100	image->sym_vvar_start;
	101
	102	/*
	103	* Sanity check: a symbol offset of zero means that the page
	104	* does not exist for this vdso image, not that the page is at
	105	* offset zero relative to the text mapping. This should be
	106	* impossible here, because sym_offset should only be zero for
	107	* the page past the end of the vvar mapping.
	108	*/
	109	if (sym_offset == 0)
	110	return VM_FAULT_SIGBUS;
	111
	112	if (sym_offset == image->sym_vvar_page) {
1a29d85e	113	ret = vm_insert_pfn(vma, vmf->address,
a48a7042	114	__pa_symbol(&__vvar_page) >> PAGE_SHIFT);
a48a7042 AL	115	} else if (sym_offset == image->sym_pvclock_page) {
	116	struct pvclock_vsyscall_time_info *pvti =
	117	pvclock_pvti_cpu0_va();
bd902c53	118	if (pvti && vclock_was_used(VCLOCK_PVCLOCK)) {
a48a7042 AL	119	ret = vm_insert_pfn(
a48a7042 AL	120	vma,
1a29d85e	121	vmf->address,
a48a7042 AL	122	__pa(pvti) >> PAGE_SHIFT);
	123	}
	124	}
	125
	126	if (ret == 0 \|\| ret == -EBUSY)
	127	return VM_FAULT_NOPAGE;
	128
	129	return VM_FAULT_SIGBUS;
	130	}
	131
2eefd878 DS	132	static const struct vm_special_mapping vdso_mapping = {
	133	.name = "[vdso]",
	134	.fault = vdso_fault,
	135	.mremap = vdso_mremap,
	136	};
	137	static const struct vm_special_mapping vvar_mapping = {
	138	.name = "[vvar]",
	139	.fault = vvar_fault,
	140	};
	141
576ebfef DS	142	/*
	143	* Add vdso and vvar mappings to current process.
	144	* @image - blob to map
	145	* @addr - request a specific address (zero to map at free addr)
	146	*/
	147	static int map_vdso(const struct vdso_image *image, unsigned long addr)
2aae950b AK	148	{
2aae950b AK	149	struct mm_struct *mm = current->mm;
18d0a6fd	150	struct vm_area_struct *vma;
576ebfef	151	unsigned long text_start;
18d0a6fd	152	int ret = 0;
b059a453	153
69048176 MH	154	if (down_write_killable(&mm->mmap_sem))
69048176 MH	155	return -EINTR;
18d0a6fd	156
e6577a7c AL	157	addr = get_unmapped_area(NULL, addr,
e6577a7c AL	158	image->size - image->sym_vvar_start, 0, 0);
2aae950b AK	159	if (IS_ERR_VALUE(addr)) {
	160	ret = addr;
	161	goto up_fail;
	162	}
	163
e6577a7c	164	text_start = addr - image->sym_vvar_start;
f7b6eb3f	165
18d0a6fd AL	166	/*
	167	* MAYWRITE to allow gdb to COW and set breakpoints
	168	*/
a62c34bd	169	vma = _install_special_mapping(mm,
e6577a7c	170	text_start,
a62c34bd AL	171	image->size,
	172	VM_READ\|VM_EXEC\|
	173	VM_MAYREAD\|VM_MAYWRITE\|VM_MAYEXEC,
b059a453	174	&vdso_mapping);
18d0a6fd	175
a62c34bd AL	176	if (IS_ERR(vma)) {
a62c34bd AL	177	ret = PTR_ERR(vma);
18d0a6fd	178	goto up_fail;
a62c34bd	179	}
18d0a6fd AL	180
18d0a6fd AL	181	vma = _install_special_mapping(mm,
e6577a7c AL	182	addr,
e6577a7c AL	183	-image->sym_vvar_start,
a48a7042 AL	184	VM_READ\|VM_MAYREAD\|VM_IO\|VM_DONTDUMP\|
a48a7042 AL	185	VM_PFNMAP,
a62c34bd	186	&vvar_mapping);
18d0a6fd AL	187
	188	if (IS_ERR(vma)) {
	189	ret = PTR_ERR(vma);
897ab3e0	190	do_munmap(mm, text_start, image->size, NULL);
67dece7d DS	191	} else {
	192	current->mm->context.vdso = (void __user *)text_start;
	193	current->mm->context.vdso_image = image;
f7b6eb3f	194	}
2aae950b	195
2aae950b AK	196	up_fail:
	197	up_write(&mm->mmap_sem);
	198	return ret;
	199	}
	200
3947f493 IM	201	#ifdef CONFIG_X86_64
	202	/*
	203	* Put the vdso above the (randomized) stack with another randomized
	204	* offset. This way there is no hole in the middle of address space.
	205	* To save memory make sure it is still in the same PTE as the stack
	206	* top. This doesn't give that many random bits.
	207	*
	208	* Note that this algorithm is imperfect: the distribution of the vdso
	209	* start address within a PMD is biased toward the end.
	210	*
	211	* Only used for the 64-bit and x32 vdsos.
	212	*/
	213	static unsigned long vdso_addr(unsigned long start, unsigned len)
	214	{
	215	unsigned long addr, end;
	216	unsigned offset;
	217
	218	/*
	219	* Round up the start address. It can start out unaligned as a result
	220	* of stack start randomization.
	221	*/
	222	start = PAGE_ALIGN(start);
	223
	224	/* Round the lowest possible end address up to a PMD boundary. */
	225	end = (start + len + PMD_SIZE - 1) & PMD_MASK;
	226	if (end >= TASK_SIZE_MAX)
	227	end = TASK_SIZE_MAX;
	228	end -= len;
	229
	230	if (end > start) {
	231	offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);
	232	addr = start + (offset << PAGE_SHIFT);
	233	} else {
	234	addr = start;
	235	}
	236
	237	/*
	238	* Forcibly align the final address in case we have a hardware
	239	* issue that requires alignment for performance reasons.
	240	*/
	241	addr = align_vdso_addr(addr);
	242
	243	return addr;
	244	}
	245
576ebfef DS	246	static int map_vdso_randomized(const struct vdso_image *image)
576ebfef DS	247	{
3947f493 IM	248	unsigned long addr = vdso_addr(current->mm->start_stack, image->size-image->sym_vvar_start);
3947f493 IM	249
576ebfef DS	250	return map_vdso(image, addr);
576ebfef DS	251	}
3947f493	252	#endif
576ebfef	253
2eefd878 DS	254	int map_vdso_once(const struct vdso_image *image, unsigned long addr)
	255	{
	256	struct mm_struct *mm = current->mm;
	257	struct vm_area_struct *vma;
	258
	259	down_write(&mm->mmap_sem);
	260	/*
	261	* Check if we have already mapped vdso blob - fail to prevent
	262	* abusing from userspace install_speciall_mapping, which may
	263	* not do accounting and rlimit right.
	264	* We could search vma near context.vdso, but it's a slowpath,
	265	* so let's explicitely check all VMAs to be completely sure.
	266	*/
	267	for (vma = mm->mmap; vma; vma = vma->vm_next) {
	268	if (vma_is_special_mapping(vma, &vdso_mapping) \|\|
	269	vma_is_special_mapping(vma, &vvar_mapping)) {
	270	up_write(&mm->mmap_sem);
	271	return -EEXIST;
	272	}
	273	}
	274	up_write(&mm->mmap_sem);
	275
	276	return map_vdso(image, addr);
	277	}
	278
ab8b82ee	279	#if defined(CONFIG_X86_32) \|\| defined(CONFIG_IA32_EMULATION)
18d0a6fd AL	280	static int load_vdso32(void)
18d0a6fd AL	281	{
18d0a6fd AL	282	if (vdso32_enabled != 1) /* Other values all mean "disabled" */
	283	return 0;
	284
576ebfef	285	return map_vdso(&vdso_image_32, 0);
18d0a6fd AL	286	}
	287	#endif
	288
	289	#ifdef CONFIG_X86_64
1a21d4e0 L	290	int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
1a21d4e0 L	291	{
18d0a6fd AL	292	if (!vdso64_enabled)
	293	return 0;
	294
576ebfef	295	return map_vdso_randomized(&vdso_image_64);
1a21d4e0 L	296	}
1a21d4e0 L	297
18d0a6fd AL	298	#ifdef CONFIG_COMPAT
	299	int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
	300	int uses_interp)
	301	{
1a21d4e0	302	#ifdef CONFIG_X86_X32_ABI
18d0a6fd AL	303	if (test_thread_flag(TIF_X32)) {
	304	if (!vdso64_enabled)
	305	return 0;
576ebfef	306	return map_vdso_randomized(&vdso_image_x32);
18d0a6fd AL	307	}
18d0a6fd AL	308	#endif
ab8b82ee	309	#ifdef CONFIG_IA32_EMULATION
18d0a6fd	310	return load_vdso32();
ab8b82ee BG	311	#else
	312	return 0;
	313	#endif
18d0a6fd AL	314	}
	315	#endif
	316	#else
	317	int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
1a21d4e0	318	{
18d0a6fd	319	return load_vdso32();
1a21d4e0 L	320	}
	321	#endif
	322
18d0a6fd	323	#ifdef CONFIG_X86_64
2aae950b AK	324	static __init int vdso_setup(char *s)
2aae950b AK	325	{
3d7ee969	326	vdso64_enabled = simple_strtoul(s, NULL, 0);
2aae950b AK	327	return 0;
	328	}
	329	__setup("vdso=", vdso_setup);
b4b541a6	330	#endif
d4f829dd AL	331
d4f829dd AL	332	#ifdef CONFIG_X86_64
1c0c1b93	333	static void vgetcpu_cpu_init(void *arg)
d4f829dd	334	{
1c0c1b93	335	int cpu = smp_processor_id();
a92f101b	336	struct desc_struct d = { };
d4f829dd AL	337	unsigned long node = 0;
	338	#ifdef CONFIG_NUMA
	339	node = cpu_to_node(cpu);
	340	#endif
8c725306	341	if (static_cpu_has(X86_FEATURE_RDTSCP))
d4f829dd AL	342	write_rdtscp_aux((node << 12) \| cpu);
	343
	344	/*
25880156 AL	345	* Store cpu number in limit so that it can be loaded
	346	* quickly in user space in vgetcpu. (12 bits for the CPU
	347	* and 8 bits for the node)
d4f829dd	348	*/
a92f101b AM	349	d.limit0 = cpu \| ((node & 0xf) << 12);
	350	d.limit = node >> 4;
	351	d.type = 5; /* RO data, expand down, accessed */
	352	d.dpl = 3; /* Visible to user code */
	353	d.s = 1; /* Not a system segment */
	354	d.p = 1; /* Present */
	355	d.d = 1; /* 32-bit */
d4f829dd	356
69218e47	357	write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);
d4f829dd AL	358	}
d4f829dd AL	359
07d36c9e	360	static int vgetcpu_online(unsigned int cpu)
d4f829dd	361	{
07d36c9e	362	return smp_call_function_single(cpu, vgetcpu_cpu_init, NULL, 1);
d4f829dd AL	363	}
d4f829dd AL	364
1c0c1b93	365	static int __init init_vdso(void)
d4f829dd	366	{
1c0c1b93 AL	367	init_vdso_image(&vdso_image_64);
	368
	369	#ifdef CONFIG_X86_X32_ABI
	370	init_vdso_image(&vdso_image_x32);
	371	#endif
	372
d4f829dd	373	/* notifier priority > KVM */
07d36c9e	374	return cpuhp_setup_state(CPUHP_AP_X86_VDSO_VMA_ONLINE,
73c1b41e	375	"x86/vdso/vma:online", vgetcpu_online, NULL);
d4f829dd	376	}
1c0c1b93 AL	377	subsys_initcall(init_vdso);
1c0c1b93 AL	378	#endif /* CONFIG_X86_64 */