[linux-block.git] / arch / s390 / kernel / vdso.c

/*
 * vdso setup for s390
 *
 *  Copyright IBM Corp. 2008
 *  Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License (version 2 only)
 * as published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/security.h>
#include <linux/bootmem.h>
#include <linux/compat.h>
#include <asm/asm-offsets.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/sections.h>
#include <asm/vdso.h>

#if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
extern char vdso32_start, vdso32_end;
static void *vdso32_kbase = &vdso32_start;
static unsigned int vdso32_pages;
static struct page **vdso32_pagelist;
#endif

#ifdef CONFIG_64BIT
extern char vdso64_start, vdso64_end;
static void *vdso64_kbase = &vdso64_start;
static unsigned int vdso64_pages;
static struct page **vdso64_pagelist;
#endif /* CONFIG_64BIT */

/*
 * Should the kernel map a VDSO page into processes and pass its
 * address down to glibc upon exec()?
 */
unsigned int __read_mostly vdso_enabled = 1;

static int __init vdso_setup(char *s)
{
	unsigned long val;
	int rc;

	rc = 0;
	if (strncmp(s, "on", 3) == 0)
		vdso_enabled = 1;
	else if (strncmp(s, "off", 4) == 0)
		vdso_enabled = 0;
	else {
		rc = strict_strtoul(s, 0, &val);
		vdso_enabled = rc ? 0 : !!val;
	}
	return !rc;
}
__setup("vdso=", vdso_setup);

/*
 * The vdso data page
 */
static union {
	struct vdso_data	data;
	u8			page[PAGE_SIZE];
} vdso_data_store __page_aligned_data;
struct vdso_data *vdso_data = &vdso_data_store.data;

/*
 * Setup vdso data page.
 */
static void vdso_init_data(struct vdso_data *vd)
{
	vd->ectg_available = user_mode != HOME_SPACE_MODE && test_facility(31);
}

#ifdef CONFIG_64BIT
/*
 * Allocate/free per cpu vdso data.
 */
#define SEGMENT_ORDER	2

int vdso_alloc_per_cpu(struct _lowcore *lowcore)
{
	unsigned long segment_table, page_table, page_frame;
	u32 *psal, *aste;
	int i;

	lowcore->vdso_per_cpu_data = __LC_PASTE;

	if (user_mode == HOME_SPACE_MODE || !vdso_enabled)
		return 0;

	segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
	page_table = get_zeroed_page(GFP_KERNEL | GFP_DMA);
	page_frame = get_zeroed_page(GFP_KERNEL);
	if (!segment_table || !page_table || !page_frame)
		goto out;

	clear_table((unsigned long *) segment_table, _SEGMENT_ENTRY_EMPTY,
		    PAGE_SIZE << SEGMENT_ORDER);
	clear_table((unsigned long *) page_table, _PAGE_TYPE_EMPTY,
		    256*sizeof(unsigned long));

	*(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table;
	*(unsigned long *) page_table = _PAGE_RO + page_frame;

	psal = (u32 *) (page_table + 256*sizeof(unsigned long));
	aste = psal + 32;

	for (i = 4; i < 32; i += 4)
		psal[i] = 0x80000000;

	lowcore->paste[4] = (u32)(addr_t) psal;
	psal[0] = 0x20000000;
	psal[2] = (u32)(addr_t) aste;
	*(unsigned long *) (aste + 2) = segment_table +
		_ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT;
	aste[4] = (u32)(addr_t) psal;
	lowcore->vdso_per_cpu_data = page_frame;

	return 0;

out:
	free_page(page_frame);
	free_page(page_table);
	free_pages(segment_table, SEGMENT_ORDER);
	return -ENOMEM;
}

void vdso_free_per_cpu(struct _lowcore *lowcore)
{
	unsigned long segment_table, page_table, page_frame;
	u32 *psal, *aste;

	if (user_mode == HOME_SPACE_MODE || !vdso_enabled)
		return;

	psal = (u32 *)(addr_t) lowcore->paste[4];
	aste = (u32 *)(addr_t) psal[2];
	segment_table = *(unsigned long *)(aste + 2) & PAGE_MASK;
	page_table = *(unsigned long *) segment_table;
	page_frame = *(unsigned long *) page_table;

	free_page(page_frame);
	free_page(page_table);
	free_pages(segment_table, SEGMENT_ORDER);
}

static void vdso_init_cr5(void)
{
	unsigned long cr5;

	if (user_mode == HOME_SPACE_MODE || !vdso_enabled)
		return;
	cr5 = offsetof(struct _lowcore, paste);
	__ctl_load(cr5, 5, 5);
}
#endif /* CONFIG_64BIT */

/*
 * This is called from binfmt_elf, we create the special vma for the
 * vDSO and insert it into the mm struct tree
 */
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
	struct mm_struct *mm = current->mm;
	struct page **vdso_pagelist;
	unsigned long vdso_pages;
	unsigned long vdso_base;
	int rc;

	if (!vdso_enabled)
		return 0;
	/*
	 * Only map the vdso for dynamically linked elf binaries.
	 */
	if (!uses_interp)
		return 0;

#ifdef CONFIG_64BIT
	vdso_pagelist = vdso64_pagelist;
	vdso_pages = vdso64_pages;
#ifdef CONFIG_COMPAT
	if (is_compat_task()) {
		vdso_pagelist = vdso32_pagelist;
		vdso_pages = vdso32_pages;
	}
#endif
#else
	vdso_pagelist = vdso32_pagelist;
	vdso_pages = vdso32_pages;
#endif

	/*
	 * vDSO has a problem and was disabled, just don't "enable" it for
	 * the process
	 */
	if (vdso_pages == 0)
		return 0;

	current->mm->context.vdso_base = 0;

	/*
	 * pick a base address for the vDSO in process space. We try to put
	 * it at vdso_base which is the "natural" base for it, but we might
	 * fail and end up putting it elsewhere.
	 */
	down_write(&mm->mmap_sem);
	vdso_base = get_unmapped_area(NULL, 0, vdso_pages << PAGE_SHIFT, 0, 0);
	if (IS_ERR_VALUE(vdso_base)) {
		rc = vdso_base;
		goto out_up;
	}

	/*
	 * Put vDSO base into mm struct. We need to do this before calling
	 * install_special_mapping or the perf counter mmap tracking code
	 * will fail to recognise it as a vDSO (since arch_vma_name fails).
	 */
	current->mm->context.vdso_base = vdso_base;

	/*
	 * our vma flags don't have VM_WRITE so by default, the process
	 * isn't allowed to write those pages.
	 * gdb can break that with ptrace interface, and thus trigger COW
	 * on those pages but it's then your responsibility to never do that
	 * on the "data" page of the vDSO or you'll stop getting kernel
	 * updates and your nice userland gettimeofday will be totally dead.
	 * It's fine to use that for setting breakpoints in the vDSO code
	 * pages though
	 *
	 * 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.
	 */
	rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
				     VM_READ|VM_EXEC|
				     VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
				     VM_ALWAYSDUMP,
				     vdso_pagelist);
	if (rc)
		current->mm->context.vdso_base = 0;
out_up:
	up_write(&mm->mmap_sem);
	return rc;
}

const char *arch_vma_name(struct vm_area_struct *vma)
{
	if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base)
		return "[vdso]";
	return NULL;
}

static int __init vdso_init(void)
{
	int i;

	if (!vdso_enabled)
		return 0;
	vdso_init_data(vdso_data);
#if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
	/* Calculate the size of the 32 bit vDSO */
	vdso32_pages = ((&vdso32_end - &vdso32_start
			 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;

	/* Make sure pages are in the correct state */
	vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 1),
				  GFP_KERNEL);
	BUG_ON(vdso32_pagelist == NULL);
	for (i = 0; i < vdso32_pages - 1; i++) {
		struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
		ClearPageReserved(pg);
		get_page(pg);
		vdso32_pagelist[i] = pg;
	}
	vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data);
	vdso32_pagelist[vdso32_pages] = NULL;
#endif

#ifdef CONFIG_64BIT
	/* Calculate the size of the 64 bit vDSO */
	vdso64_pages = ((&vdso64_end - &vdso64_start
			 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;

	/* Make sure pages are in the correct state */
	vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 1),
				  GFP_KERNEL);
	BUG_ON(vdso64_pagelist == NULL);
	for (i = 0; i < vdso64_pages - 1; i++) {
		struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
		ClearPageReserved(pg);
		get_page(pg);
		vdso64_pagelist[i] = pg;
	}
	vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
	vdso64_pagelist[vdso64_pages] = NULL;
	if (vdso_alloc_per_cpu(&S390_lowcore))
		BUG();
	vdso_init_cr5();
#endif /* CONFIG_64BIT */

	get_page(virt_to_page(vdso_data));

	smp_wmb();

	return 0;
}
early_initcall(vdso_init);

int in_gate_area_no_mm(unsigned long addr)
{
	return 0;
}

int in_gate_area(struct mm_struct *mm, unsigned long addr)
{
	return 0;
}

struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
	return NULL;
}
Commit	Line	Data
b020632e MS	1	/*
	2	* vdso setup for s390
	3	*
	4	* Copyright IBM Corp. 2008
	5	* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License (version 2 only)
	9	* as published by the Free Software Foundation.
	10	*/
	11
	12	#include <linux/module.h>
	13	#include <linux/errno.h>
	14	#include <linux/sched.h>
	15	#include <linux/kernel.h>
	16	#include <linux/mm.h>
	17	#include <linux/smp.h>
	18	#include <linux/stddef.h>
	19	#include <linux/unistd.h>
	20	#include <linux/slab.h>
	21	#include <linux/user.h>
	22	#include <linux/elf.h>
	23	#include <linux/security.h>
	24	#include <linux/bootmem.h>
7757591a	25	#include <linux/compat.h>
cbb870c8	26	#include <asm/asm-offsets.h>
b020632e MS	27	#include <asm/pgtable.h>
	28	#include <asm/system.h>
	29	#include <asm/processor.h>
	30	#include <asm/mmu.h>
	31	#include <asm/mmu_context.h>
	32	#include <asm/sections.h>
	33	#include <asm/vdso.h>
	34
b020632e MS	35	#if defined(CONFIG_32BIT) \|\| defined(CONFIG_COMPAT)
	36	extern char vdso32_start, vdso32_end;
	37	static void *vdso32_kbase = &vdso32_start;
	38	static unsigned int vdso32_pages;
	39	static struct page **vdso32_pagelist;
	40	#endif
	41
	42	#ifdef CONFIG_64BIT
	43	extern char vdso64_start, vdso64_end;
	44	static void *vdso64_kbase = &vdso64_start;
	45	static unsigned int vdso64_pages;
	46	static struct page **vdso64_pagelist;
	47	#endif /* CONFIG_64BIT */
	48
	49	/*
	50	* Should the kernel map a VDSO page into processes and pass its
	51	* address down to glibc upon exec()?
	52	*/
	53	unsigned int __read_mostly vdso_enabled = 1;
	54
	55	static int __init vdso_setup(char *s)
	56	{
7aa79f94 MS	57	unsigned long val;
	58	int rc;
	59
	60	rc = 0;
	61	if (strncmp(s, "on", 3) == 0)
	62	vdso_enabled = 1;
	63	else if (strncmp(s, "off", 4) == 0)
	64	vdso_enabled = 0;
	65	else {
	66	rc = strict_strtoul(s, 0, &val);
	67	vdso_enabled = rc ? 0 : !!val;
	68	}
	69	return !rc;
b020632e MS	70	}
	71	__setup("vdso=", vdso_setup);
	72
	73	/*
	74	* The vdso data page
	75	*/
	76	static union {
	77	struct vdso_data data;
	78	u8 page[PAGE_SIZE];
abe1ee3a	79	} vdso_data_store __page_aligned_data;
b020632e MS	80	struct vdso_data *vdso_data = &vdso_data_store.data;
b020632e MS	81
c742b31c MS	82	/*
	83	* Setup vdso data page.
	84	*/
	85	static void vdso_init_data(struct vdso_data *vd)
	86	{
14375bc4	87	vd->ectg_available = user_mode != HOME_SPACE_MODE && test_facility(31);
c742b31c MS	88	}
	89
	90	#ifdef CONFIG_64BIT
c742b31c MS	91	/*
	92	* Allocate/free per cpu vdso data.
	93	*/
c742b31c	94	#define SEGMENT_ORDER 2
c742b31c	95
8b646bd7	96	int vdso_alloc_per_cpu(struct _lowcore *lowcore)
c742b31c MS	97	{
	98	unsigned long segment_table, page_table, page_frame;
	99	u32 psal, aste;
	100	int i;
	101
	102	lowcore->vdso_per_cpu_data = __LC_PASTE;
	103
b11b5334	104	if (user_mode == HOME_SPACE_MODE \|\| !vdso_enabled)
c742b31c MS	105	return 0;
	106
	107	segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
	108	page_table = get_zeroed_page(GFP_KERNEL \| GFP_DMA);
	109	page_frame = get_zeroed_page(GFP_KERNEL);
	110	if (!segment_table \|\| !page_table \|\| !page_frame)
	111	goto out;
	112
	113	clear_table((unsigned long *) segment_table, _SEGMENT_ENTRY_EMPTY,
	114	PAGE_SIZE << SEGMENT_ORDER);
	115	clear_table((unsigned long *) page_table, _PAGE_TYPE_EMPTY,
	116	256*sizeof(unsigned long));
	117
	118	(unsigned long ) segment_table = _SEGMENT_ENTRY + page_table;
	119	(unsigned long ) page_table = _PAGE_RO + page_frame;
	120
	121	psal = (u32 ) (page_table + 256sizeof(unsigned long));
	122	aste = psal + 32;
	123
	124	for (i = 4; i < 32; i += 4)
	125	psal[i] = 0x80000000;
	126
	127	lowcore->paste[4] = (u32)(addr_t) psal;
	128	psal[0] = 0x20000000;
	129	psal[2] = (u32)(addr_t) aste;
	130	(unsigned long ) (aste + 2) = segment_table +
	131	_ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT;
	132	aste[4] = (u32)(addr_t) psal;
	133	lowcore->vdso_per_cpu_data = page_frame;
	134
c742b31c MS	135	return 0;
	136
	137	out:
	138	free_page(page_frame);
	139	free_page(page_table);
	140	free_pages(segment_table, SEGMENT_ORDER);
	141	return -ENOMEM;
	142	}
	143
8b646bd7	144	void vdso_free_per_cpu(struct _lowcore *lowcore)
c742b31c MS	145	{
	146	unsigned long segment_table, page_table, page_frame;
	147	u32 psal, aste;
	148
b11b5334	149	if (user_mode == HOME_SPACE_MODE \|\| !vdso_enabled)
c742b31c MS	150	return;
	151
	152	psal = (u32 *)(addr_t) lowcore->paste[4];
	153	aste = (u32 *)(addr_t) psal[2];
	154	segment_table = (unsigned long )(aste + 2) & PAGE_MASK;
	155	page_table = (unsigned long ) segment_table;
	156	page_frame = (unsigned long ) page_table;
	157
	158	free_page(page_frame);
	159	free_page(page_table);
	160	free_pages(segment_table, SEGMENT_ORDER);
	161	}
c742b31c	162
8b646bd7	163	static void vdso_init_cr5(void)
c742b31c MS	164	{
	165	unsigned long cr5;
	166
8b646bd7 MS	167	if (user_mode == HOME_SPACE_MODE \|\| !vdso_enabled)
8b646bd7 MS	168	return;
c742b31c MS	169	cr5 = offsetof(struct _lowcore, paste);
	170	__ctl_load(cr5, 5, 5);
	171	}
c742b31c MS	172	#endif /* CONFIG_64BIT */
c742b31c MS	173
b020632e MS	174	/*
	175	* This is called from binfmt_elf, we create the special vma for the
	176	* vDSO and insert it into the mm struct tree
	177	*/
	178	int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
	179	{
	180	struct mm_struct *mm = current->mm;
	181	struct page **vdso_pagelist;
	182	unsigned long vdso_pages;
	183	unsigned long vdso_base;
	184	int rc;
	185
	186	if (!vdso_enabled)
	187	return 0;
	188	/*
	189	* Only map the vdso for dynamically linked elf binaries.
	190	*/
	191	if (!uses_interp)
	192	return 0;
	193
b020632e MS	194	#ifdef CONFIG_64BIT
	195	vdso_pagelist = vdso64_pagelist;
	196	vdso_pages = vdso64_pages;
	197	#ifdef CONFIG_COMPAT
7757591a	198	if (is_compat_task()) {
b020632e MS	199	vdso_pagelist = vdso32_pagelist;
	200	vdso_pages = vdso32_pages;
	201	}
	202	#endif
	203	#else
	204	vdso_pagelist = vdso32_pagelist;
	205	vdso_pages = vdso32_pages;
	206	#endif
	207
	208	/*
	209	* vDSO has a problem and was disabled, just don't "enable" it for
	210	* the process
	211	*/
	212	if (vdso_pages == 0)
	213	return 0;
	214
	215	current->mm->context.vdso_base = 0;
	216
	217	/*
	218	* pick a base address for the vDSO in process space. We try to put
	219	* it at vdso_base which is the "natural" base for it, but we might
	220	* fail and end up putting it elsewhere.
	221	*/
	222	down_write(&mm->mmap_sem);
e7828bbd	223	vdso_base = get_unmapped_area(NULL, 0, vdso_pages << PAGE_SHIFT, 0, 0);
b020632e MS	224	if (IS_ERR_VALUE(vdso_base)) {
	225	rc = vdso_base;
	226	goto out_up;
	227	}
	228
930e44fb HC	229	/*
	230	* Put vDSO base into mm struct. We need to do this before calling
	231	* install_special_mapping or the perf counter mmap tracking code
	232	* will fail to recognise it as a vDSO (since arch_vma_name fails).
	233	*/
	234	current->mm->context.vdso_base = vdso_base;
	235
b020632e MS	236	/*
	237	* our vma flags don't have VM_WRITE so by default, the process
	238	* isn't allowed to write those pages.
	239	* gdb can break that with ptrace interface, and thus trigger COW
	240	* on those pages but it's then your responsibility to never do that
	241	* on the "data" page of the vDSO or you'll stop getting kernel
	242	* updates and your nice userland gettimeofday will be totally dead.
	243	* It's fine to use that for setting breakpoints in the vDSO code
	244	* pages though
	245	*
	246	* Make sure the vDSO gets into every core dump.
	247	* Dumping its contents makes post-mortem fully interpretable later
	248	* without matching up the same kernel and hardware config to see
	249	* what PC values meant.
	250	*/
	251	rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
	252	VM_READ\|VM_EXEC\|
	253	VM_MAYREAD\|VM_MAYWRITE\|VM_MAYEXEC\|
	254	VM_ALWAYSDUMP,
	255	vdso_pagelist);
	256	if (rc)
930e44fb	257	current->mm->context.vdso_base = 0;
b020632e MS	258	out_up:
	259	up_write(&mm->mmap_sem);
	260	return rc;
	261	}
	262
	263	const char arch_vma_name(struct vm_area_struct vma)
	264	{
	265	if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base)
	266	return "[vdso]";
	267	return NULL;
	268	}
	269
	270	static int __init vdso_init(void)
	271	{
	272	int i;
	273
c742b31c MS	274	if (!vdso_enabled)
	275	return 0;
	276	vdso_init_data(vdso_data);
b020632e MS	277	#if defined(CONFIG_32BIT) \|\| defined(CONFIG_COMPAT)
	278	/* Calculate the size of the 32 bit vDSO */
	279	vdso32_pages = ((&vdso32_end - &vdso32_start
	280	+ PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
	281
	282	/* Make sure pages are in the correct state */
	283	vdso32_pagelist = kzalloc(sizeof(struct page ) (vdso32_pages + 1),
	284	GFP_KERNEL);
	285	BUG_ON(vdso32_pagelist == NULL);
	286	for (i = 0; i < vdso32_pages - 1; i++) {
	287	struct page pg = virt_to_page(vdso32_kbase + iPAGE_SIZE);
	288	ClearPageReserved(pg);
	289	get_page(pg);
	290	vdso32_pagelist[i] = pg;
	291	}
	292	vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data);
	293	vdso32_pagelist[vdso32_pages] = NULL;
	294	#endif
	295
	296	#ifdef CONFIG_64BIT
	297	/* Calculate the size of the 64 bit vDSO */
	298	vdso64_pages = ((&vdso64_end - &vdso64_start
	299	+ PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
	300
	301	/* Make sure pages are in the correct state */
	302	vdso64_pagelist = kzalloc(sizeof(struct page ) (vdso64_pages + 1),
	303	GFP_KERNEL);
	304	BUG_ON(vdso64_pagelist == NULL);
	305	for (i = 0; i < vdso64_pages - 1; i++) {
	306	struct page pg = virt_to_page(vdso64_kbase + iPAGE_SIZE);
	307	ClearPageReserved(pg);
	308	get_page(pg);
	309	vdso64_pagelist[i] = pg;
	310	}
	311	vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
	312	vdso64_pagelist[vdso64_pages] = NULL;
8b646bd7	313	if (vdso_alloc_per_cpu(&S390_lowcore))
81ffa041	314	BUG();
c742b31c	315	vdso_init_cr5();
b020632e MS	316	#endif /* CONFIG_64BIT */
	317
	318	get_page(virt_to_page(vdso_data));
	319
	320	smp_wmb();
	321
	322	return 0;
	323	}
8b646bd7	324	early_initcall(vdso_init);
b020632e	325
cae5d390	326	int in_gate_area_no_mm(unsigned long addr)
b020632e MS	327	{
	328	return 0;
	329	}
	330
83b964bb	331	int in_gate_area(struct mm_struct *mm, unsigned long addr)
b020632e MS	332	{
	333	return 0;
	334	}
	335
31db58b3	336	struct vm_area_struct get_gate_vma(struct mm_struct mm)
b020632e MS	337	{
	338	return NULL;
	339	}