[linux-2.6-block.git] / mm / process_vm_access.c

/*
 * linux/mm/process_vm_access.c
 *
 * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/mm.h>
#include <linux/uio.h>
#include <linux/sched.h>
#include <linux/highmem.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/syscalls.h>

#ifdef CONFIG_COMPAT
#include <linux/compat.h>
#endif

/**
 * process_vm_rw_pages - read/write pages from task specified
 * @pages: array of pointers to pages we want to copy
 * @start_offset: offset in page to start copying from/to
 * @len: number of bytes to copy
 * @iter: where to copy to/from locally
 * @vm_write: 0 means copy from, 1 means copy to
 * Returns 0 on success, error code otherwise
 */
static int process_vm_rw_pages(struct page **pages,
			       unsigned offset,
			       size_t len,
			       struct iov_iter *iter,
			       int vm_write)
{
	/* Do the copy for each page */
	while (len && iov_iter_count(iter)) {
		struct page *page = *pages++;
		size_t copy = PAGE_SIZE - offset;
		size_t copied;

		if (copy > len)
			copy = len;

		if (vm_write) {
			copied = copy_page_from_iter(page, offset, copy, iter);
			set_page_dirty_lock(page);
		} else {
			copied = copy_page_to_iter(page, offset, copy, iter);
		}
		len -= copied;
		if (copied < copy && iov_iter_count(iter))
			return -EFAULT;
		offset = 0;
	}
	return 0;
}

/* Maximum number of pages kmalloc'd to hold struct page's during copy */
#define PVM_MAX_KMALLOC_PAGES (PAGE_SIZE * 2)

/**
 * process_vm_rw_single_vec - read/write pages from task specified
 * @addr: start memory address of target process
 * @len: size of area to copy to/from
 * @iter: where to copy to/from locally
 * @process_pages: struct pages area that can store at least
 *  nr_pages_to_copy struct page pointers
 * @mm: mm for task
 * @task: task to read/write from
 * @vm_write: 0 means copy from, 1 means copy to
 * Returns 0 on success or on failure error code
 */
static int process_vm_rw_single_vec(unsigned long addr,
				    unsigned long len,
				    struct iov_iter *iter,
				    struct page **process_pages,
				    struct mm_struct *mm,
				    struct task_struct *task,
				    int vm_write)
{
	unsigned long pa = addr & PAGE_MASK;
	unsigned long start_offset = addr - pa;
	unsigned long nr_pages;
	ssize_t rc = 0;
	unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
		/ sizeof(struct pages *);

	/* Work out address and page range required */
	if (len == 0)
		return 0;
	nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;

	while (!rc && nr_pages && iov_iter_count(iter)) {
		int pages = min(nr_pages, max_pages_per_loop);
		size_t bytes;

		/* Get the pages we're interested in */
		pages = get_user_pages_unlocked(task, mm, pa, pages,
						vm_write, 0, process_pages);
		if (pages <= 0)
			return -EFAULT;

		bytes = pages * PAGE_SIZE - start_offset;
		if (bytes > len)
			bytes = len;

		rc = process_vm_rw_pages(process_pages,
					 start_offset, bytes, iter,
					 vm_write);
		len -= bytes;
		start_offset = 0;
		nr_pages -= pages;
		pa += pages * PAGE_SIZE;
		while (pages)
			put_page(process_pages[--pages]);
	}

	return rc;
}

/* Maximum number of entries for process pages array
   which lives on stack */
#define PVM_MAX_PP_ARRAY_COUNT 16

/**
 * process_vm_rw_core - core of reading/writing pages from task specified
 * @pid: PID of process to read/write from/to
 * @iter: where to copy to/from locally
 * @rvec: iovec array specifying where to copy to/from in the other process
 * @riovcnt: size of rvec array
 * @flags: currently unused
 * @vm_write: 0 if reading from other process, 1 if writing to other process
 * Returns the number of bytes read/written or error code. May
 *  return less bytes than expected if an error occurs during the copying
 *  process.
 */
static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter,
				  const struct iovec *rvec,
				  unsigned long riovcnt,
				  unsigned long flags, int vm_write)
{
	struct task_struct *task;
	struct page *pp_stack[PVM_MAX_PP_ARRAY_COUNT];
	struct page **process_pages = pp_stack;
	struct mm_struct *mm;
	unsigned long i;
	ssize_t rc = 0;
	unsigned long nr_pages = 0;
	unsigned long nr_pages_iov;
	ssize_t iov_len;
	size_t total_len = iov_iter_count(iter);

	/*
	 * Work out how many pages of struct pages we're going to need
	 * when eventually calling get_user_pages
	 */
	for (i = 0; i < riovcnt; i++) {
		iov_len = rvec[i].iov_len;
		if (iov_len > 0) {
			nr_pages_iov = ((unsigned long)rvec[i].iov_base
					+ iov_len)
				/ PAGE_SIZE - (unsigned long)rvec[i].iov_base
				/ PAGE_SIZE + 1;
			nr_pages = max(nr_pages, nr_pages_iov);
		}
	}

	if (nr_pages == 0)
		return 0;

	if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) {
		/* For reliability don't try to kmalloc more than
		   2 pages worth */
		process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES,
					      sizeof(struct pages *)*nr_pages),
					GFP_KERNEL);

		if (!process_pages)
			return -ENOMEM;
	}

	/* Get process information */
	rcu_read_lock();
	task = find_task_by_vpid(pid);
	if (task)
		get_task_struct(task);
	rcu_read_unlock();
	if (!task) {
		rc = -ESRCH;
		goto free_proc_pages;
	}

	mm = mm_access(task, PTRACE_MODE_ATTACH);
	if (!mm || IS_ERR(mm)) {
		rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
		/*
		 * Explicitly map EACCES to EPERM as EPERM is a more a
		 * appropriate error code for process_vw_readv/writev
		 */
		if (rc == -EACCES)
			rc = -EPERM;
		goto put_task_struct;
	}

	for (i = 0; i < riovcnt && iov_iter_count(iter) && !rc; i++)
		rc = process_vm_rw_single_vec(
			(unsigned long)rvec[i].iov_base, rvec[i].iov_len,
			iter, process_pages, mm, task, vm_write);

	/* copied = space before - space after */
	total_len -= iov_iter_count(iter);

	/* If we have managed to copy any data at all then
	   we return the number of bytes copied. Otherwise
	   we return the error code */
	if (total_len)
		rc = total_len;

	mmput(mm);

put_task_struct:
	put_task_struct(task);

free_proc_pages:
	if (process_pages != pp_stack)
		kfree(process_pages);
	return rc;
}

/**
 * process_vm_rw - check iovecs before calling core routine
 * @pid: PID of process to read/write from/to
 * @lvec: iovec array specifying where to copy to/from locally
 * @liovcnt: size of lvec array
 * @rvec: iovec array specifying where to copy to/from in the other process
 * @riovcnt: size of rvec array
 * @flags: currently unused
 * @vm_write: 0 if reading from other process, 1 if writing to other process
 * Returns the number of bytes read/written or error code. May
 *  return less bytes than expected if an error occurs during the copying
 *  process.
 */
static ssize_t process_vm_rw(pid_t pid,
			     const struct iovec __user *lvec,
			     unsigned long liovcnt,
			     const struct iovec __user *rvec,
			     unsigned long riovcnt,
			     unsigned long flags, int vm_write)
{
	struct iovec iovstack_l[UIO_FASTIOV];
	struct iovec iovstack_r[UIO_FASTIOV];
	struct iovec *iov_l = iovstack_l;
	struct iovec *iov_r = iovstack_r;
	struct iov_iter iter;
	ssize_t rc;
	int dir = vm_write ? WRITE : READ;

	if (flags != 0)
		return -EINVAL;

	/* Check iovecs */
	rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
	if (rc < 0)
		return rc;
	if (!iov_iter_count(&iter))
		goto free_iovecs;

	rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV,
				   iovstack_r, &iov_r);
	if (rc <= 0)
		goto free_iovecs;

	rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);

free_iovecs:
	if (iov_r != iovstack_r)
		kfree(iov_r);
	kfree(iov_l);

	return rc;
}

SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec,
		unsigned long, liovcnt, const struct iovec __user *, rvec,
		unsigned long, riovcnt,	unsigned long, flags)
{
	return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0);
}

SYSCALL_DEFINE6(process_vm_writev, pid_t, pid,
		const struct iovec __user *, lvec,
		unsigned long, liovcnt, const struct iovec __user *, rvec,
		unsigned long, riovcnt,	unsigned long, flags)
{
	return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1);
}

#ifdef CONFIG_COMPAT

static ssize_t
compat_process_vm_rw(compat_pid_t pid,
		     const struct compat_iovec __user *lvec,
		     unsigned long liovcnt,
		     const struct compat_iovec __user *rvec,
		     unsigned long riovcnt,
		     unsigned long flags, int vm_write)
{
	struct iovec iovstack_l[UIO_FASTIOV];
	struct iovec iovstack_r[UIO_FASTIOV];
	struct iovec *iov_l = iovstack_l;
	struct iovec *iov_r = iovstack_r;
	struct iov_iter iter;
	ssize_t rc = -EFAULT;
	int dir = vm_write ? WRITE : READ;

	if (flags != 0)
		return -EINVAL;

	rc = compat_import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
	if (rc < 0)
		return rc;
	if (!iov_iter_count(&iter))
		goto free_iovecs;
	rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt,
					  UIO_FASTIOV, iovstack_r,
					  &iov_r);
	if (rc <= 0)
		goto free_iovecs;

	rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);

free_iovecs:
	if (iov_r != iovstack_r)
		kfree(iov_r);
	kfree(iov_l);
	return rc;
}

COMPAT_SYSCALL_DEFINE6(process_vm_readv, compat_pid_t, pid,
		       const struct compat_iovec __user *, lvec,
		       compat_ulong_t, liovcnt,
		       const struct compat_iovec __user *, rvec,
		       compat_ulong_t, riovcnt,
		       compat_ulong_t, flags)
{
	return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
				    riovcnt, flags, 0);
}

COMPAT_SYSCALL_DEFINE6(process_vm_writev, compat_pid_t, pid,
		       const struct compat_iovec __user *, lvec,
		       compat_ulong_t, liovcnt,
		       const struct compat_iovec __user *, rvec,
		       compat_ulong_t, riovcnt,
		       compat_ulong_t, flags)
{
	return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
				    riovcnt, flags, 1);
}

#endif
Commit	Line	Data
fcf63409 CY	1	/*
	2	* linux/mm/process_vm_access.c
	3	*
	4	* Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp.
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/mm.h>
	13	#include <linux/uio.h>
	14	#include <linux/sched.h>
	15	#include <linux/highmem.h>
	16	#include <linux/ptrace.h>
	17	#include <linux/slab.h>
	18	#include <linux/syscalls.h>
	19
	20	#ifdef CONFIG_COMPAT
	21	#include <linux/compat.h>
	22	#endif
	23
	24	/**
	25	* process_vm_rw_pages - read/write pages from task specified
4bafbec7	26	* @pages: array of pointers to pages we want to copy
fcf63409 CY	27	* @start_offset: offset in page to start copying from/to
fcf63409 CY	28	* @len: number of bytes to copy
4bafbec7	29	* @iter: where to copy to/from locally
fcf63409	30	* @vm_write: 0 means copy from, 1 means copy to
fcf63409 CY	31	* Returns 0 on success, error code otherwise
fcf63409 CY	32	*/
70eca12d AV	33	static int process_vm_rw_pages(struct page **pages,
70eca12d AV	34	unsigned offset,
e21345f9	35	size_t len,
9f78bdfa	36	struct iov_iter *iter,
9acc1a0f	37	int vm_write)
fcf63409	38	{
fcf63409	39	/* Do the copy for each page */
9acc1a0f	40	while (len && iov_iter_count(iter)) {
70eca12d	41	struct page page = pages++;
e21345f9	42	size_t copy = PAGE_SIZE - offset;
70eca12d	43	size_t copied;
240f3905	44
e21345f9 AV	45	if (copy > len)
	46	copy = len;
	47
240f3905	48	if (vm_write) {
e7c24607	49	copied = copy_page_from_iter(page, offset, copy, iter);
240f3905	50	set_page_dirty_lock(page);
fcf63409	51	} else {
70eca12d	52	copied = copy_page_to_iter(page, offset, copy, iter);
fcf63409	53	}
70eca12d AV	54	len -= copied;
	55	if (copied < copy && iov_iter_count(iter))
	56	return -EFAULT;
	57	offset = 0;
fcf63409	58	}
70eca12d	59	return 0;
fcf63409 CY	60	}
	61
	62	/* Maximum number of pages kmalloc'd to hold struct page's during copy */
	63	#define PVM_MAX_KMALLOC_PAGES (PAGE_SIZE * 2)
	64
	65	/**
	66	* process_vm_rw_single_vec - read/write pages from task specified
	67	* @addr: start memory address of target process
	68	* @len: size of area to copy to/from
4bafbec7	69	* @iter: where to copy to/from locally
fcf63409 CY	70	* @process_pages: struct pages area that can store at least
	71	* nr_pages_to_copy struct page pointers
	72	* @mm: mm for task
	73	* @task: task to read/write from
	74	* @vm_write: 0 means copy from, 1 means copy to
fcf63409 CY	75	* Returns 0 on success or on failure error code
	76	*/
	77	static int process_vm_rw_single_vec(unsigned long addr,
	78	unsigned long len,
9f78bdfa	79	struct iov_iter *iter,
fcf63409 CY	80	struct page **process_pages,
	81	struct mm_struct *mm,
	82	struct task_struct *task,
9acc1a0f	83	int vm_write)
fcf63409 CY	84	{
	85	unsigned long pa = addr & PAGE_MASK;
	86	unsigned long start_offset = addr - pa;
	87	unsigned long nr_pages;
fcf63409	88	ssize_t rc = 0;
fcf63409 CY	89	unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
	90	/ sizeof(struct pages *);
	91
fcf63409 CY	92	/* Work out address and page range required */
	93	if (len == 0)
	94	return 0;
	95	nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
	96
4bafbec7 AV	97	while (!rc && nr_pages && iov_iter_count(iter)) {
	98	int pages = min(nr_pages, max_pages_per_loop);
	99	size_t bytes;
fcf63409	100
70eca12d	101	/* Get the pages we're interested in */
7e339128 AA	102	pages = get_user_pages_unlocked(task, mm, pa, pages,
7e339128 AA	103	vm_write, 0, process_pages);
4bafbec7	104	if (pages <= 0)
70eca12d AV	105	return -EFAULT;
70eca12d AV	106
4bafbec7 AV	107	bytes = pages * PAGE_SIZE - start_offset;
	108	if (bytes > len)
	109	bytes = len;
e21345f9	110
70eca12d	111	rc = process_vm_rw_pages(process_pages,
4bafbec7	112	start_offset, bytes, iter,
9acc1a0f	113	vm_write);
4bafbec7	114	len -= bytes;
fcf63409	115	start_offset = 0;
4bafbec7 AV	116	nr_pages -= pages;
	117	pa += pages * PAGE_SIZE;
	118	while (pages)
	119	put_page(process_pages[--pages]);
fcf63409 CY	120	}
	121
	122	return rc;
	123	}
	124
	125	/* Maximum number of entries for process pages array
	126	which lives on stack */
	127	#define PVM_MAX_PP_ARRAY_COUNT 16
	128
	129	/**
	130	* process_vm_rw_core - core of reading/writing pages from task specified
	131	* @pid: PID of process to read/write from/to
4bafbec7	132	* @iter: where to copy to/from locally
fcf63409 CY	133	* @rvec: iovec array specifying where to copy to/from in the other process
	134	* @riovcnt: size of rvec array
	135	* @flags: currently unused
	136	* @vm_write: 0 if reading from other process, 1 if writing to other process
	137	* Returns the number of bytes read/written or error code. May
	138	* return less bytes than expected if an error occurs during the copying
	139	* process.
	140	*/
9f78bdfa	141	static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter,
fcf63409 CY	142	const struct iovec *rvec,
	143	unsigned long riovcnt,
	144	unsigned long flags, int vm_write)
	145	{
	146	struct task_struct *task;
	147	struct page *pp_stack[PVM_MAX_PP_ARRAY_COUNT];
	148	struct page **process_pages = pp_stack;
	149	struct mm_struct *mm;
	150	unsigned long i;
	151	ssize_t rc = 0;
fcf63409 CY	152	unsigned long nr_pages = 0;
fcf63409 CY	153	unsigned long nr_pages_iov;
fcf63409	154	ssize_t iov_len;
9acc1a0f	155	size_t total_len = iov_iter_count(iter);
fcf63409 CY	156
	157	/*
	158	* Work out how many pages of struct pages we're going to need
	159	* when eventually calling get_user_pages
	160	*/
	161	for (i = 0; i < riovcnt; i++) {
	162	iov_len = rvec[i].iov_len;
	163	if (iov_len > 0) {
	164	nr_pages_iov = ((unsigned long)rvec[i].iov_base
	165	+ iov_len)
	166	/ PAGE_SIZE - (unsigned long)rvec[i].iov_base
	167	/ PAGE_SIZE + 1;
	168	nr_pages = max(nr_pages, nr_pages_iov);
	169	}
	170	}
	171
	172	if (nr_pages == 0)
	173	return 0;
	174
	175	if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) {
	176	/* For reliability don't try to kmalloc more than
	177	2 pages worth */
	178	process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES,
	179	sizeof(struct pages )nr_pages),
	180	GFP_KERNEL);
	181
	182	if (!process_pages)
	183	return -ENOMEM;
	184	}
	185
	186	/* Get process information */
	187	rcu_read_lock();
	188	task = find_task_by_vpid(pid);
	189	if (task)
	190	get_task_struct(task);
	191	rcu_read_unlock();
	192	if (!task) {
	193	rc = -ESRCH;
	194	goto free_proc_pages;
	195	}
	196
8cdb878d CY	197	mm = mm_access(task, PTRACE_MODE_ATTACH);
	198	if (!mm \|\| IS_ERR(mm)) {
	199	rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
	200	/*
	201	* Explicitly map EACCES to EPERM as EPERM is a more a
	202	* appropriate error code for process_vw_readv/writev
	203	*/
	204	if (rc == -EACCES)
	205	rc = -EPERM;
fcf63409 CY	206	goto put_task_struct;
	207	}
	208
9acc1a0f	209	for (i = 0; i < riovcnt && iov_iter_count(iter) && !rc; i++)
fcf63409 CY	210	rc = process_vm_rw_single_vec(
fcf63409 CY	211	(unsigned long)rvec[i].iov_base, rvec[i].iov_len,
9acc1a0f AV	212	iter, process_pages, mm, task, vm_write);
	213
	214	/* copied = space before - space after */
	215	total_len -= iov_iter_count(iter);
	216
	217	/* If we have managed to copy any data at all then
	218	we return the number of bytes copied. Otherwise
	219	we return the error code */
	220	if (total_len)
	221	rc = total_len;
fcf63409	222
fcf63409 CY	223	mmput(mm);
	224
	225	put_task_struct:
	226	put_task_struct(task);
	227
	228	free_proc_pages:
	229	if (process_pages != pp_stack)
	230	kfree(process_pages);
	231	return rc;
	232	}
	233
	234	/**
	235	* process_vm_rw - check iovecs before calling core routine
	236	* @pid: PID of process to read/write from/to
	237	* @lvec: iovec array specifying where to copy to/from locally
	238	* @liovcnt: size of lvec array
	239	* @rvec: iovec array specifying where to copy to/from in the other process
	240	* @riovcnt: size of rvec array
	241	* @flags: currently unused
	242	* @vm_write: 0 if reading from other process, 1 if writing to other process
	243	* Returns the number of bytes read/written or error code. May
	244	* return less bytes than expected if an error occurs during the copying
	245	* process.
	246	*/
	247	static ssize_t process_vm_rw(pid_t pid,
	248	const struct iovec __user *lvec,
	249	unsigned long liovcnt,
	250	const struct iovec __user *rvec,
	251	unsigned long riovcnt,
	252	unsigned long flags, int vm_write)
	253	{
	254	struct iovec iovstack_l[UIO_FASTIOV];
	255	struct iovec iovstack_r[UIO_FASTIOV];
	256	struct iovec *iov_l = iovstack_l;
	257	struct iovec *iov_r = iovstack_r;
9f78bdfa	258	struct iov_iter iter;
fcf63409	259	ssize_t rc;
17d17e72	260	int dir = vm_write ? WRITE : READ;
fcf63409 CY	261
	262	if (flags != 0)
	263	return -EINVAL;
	264
	265	/* Check iovecs */
17d17e72 AV	266	rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
	267	if (rc < 0)
	268	return rc;
	269	if (!iov_iter_count(&iter))
fcf63409 CY	270	goto free_iovecs;
fcf63409 CY	271
ac34ebb3 CY	272	rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV,
ac34ebb3 CY	273	iovstack_r, &iov_r);
fcf63409 CY	274	if (rc <= 0)
	275	goto free_iovecs;
	276
9f78bdfa	277	rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
fcf63409 CY	278
	279	free_iovecs:
	280	if (iov_r != iovstack_r)
	281	kfree(iov_r);
17d17e72	282	kfree(iov_l);
fcf63409 CY	283
	284	return rc;
	285	}
	286
	287	SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec,
	288	unsigned long, liovcnt, const struct iovec __user *, rvec,
	289	unsigned long, riovcnt, unsigned long, flags)
	290	{
	291	return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0);
	292	}
	293
	294	SYSCALL_DEFINE6(process_vm_writev, pid_t, pid,
	295	const struct iovec __user *, lvec,
	296	unsigned long, liovcnt, const struct iovec __user *, rvec,
	297	unsigned long, riovcnt, unsigned long, flags)
	298	{
	299	return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1);
	300	}
	301
	302	#ifdef CONFIG_COMPAT
	303
2eb2e141	304	static ssize_t
fcf63409 CY	305	compat_process_vm_rw(compat_pid_t pid,
	306	const struct compat_iovec __user *lvec,
	307	unsigned long liovcnt,
	308	const struct compat_iovec __user *rvec,
	309	unsigned long riovcnt,
	310	unsigned long flags, int vm_write)
	311	{
	312	struct iovec iovstack_l[UIO_FASTIOV];
	313	struct iovec iovstack_r[UIO_FASTIOV];
	314	struct iovec *iov_l = iovstack_l;
	315	struct iovec *iov_r = iovstack_r;
9f78bdfa	316	struct iov_iter iter;
fcf63409	317	ssize_t rc = -EFAULT;
17d17e72	318	int dir = vm_write ? WRITE : READ;
fcf63409 CY	319
	320	if (flags != 0)
	321	return -EINVAL;
	322
17d17e72 AV	323	rc = compat_import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
	324	if (rc < 0)
	325	return rc;
	326	if (!iov_iter_count(&iter))
fcf63409	327	goto free_iovecs;
ac34ebb3	328	rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt,
fcf63409	329	UIO_FASTIOV, iovstack_r,
ac34ebb3	330	&iov_r);
fcf63409 CY	331	if (rc <= 0)
	332	goto free_iovecs;
	333
9f78bdfa	334	rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
fcf63409 CY	335
	336	free_iovecs:
	337	if (iov_r != iovstack_r)
	338	kfree(iov_r);
17d17e72	339	kfree(iov_l);
fcf63409 CY	340	return rc;
	341	}
	342
2f2728f6 HC	343	COMPAT_SYSCALL_DEFINE6(process_vm_readv, compat_pid_t, pid,
	344	const struct compat_iovec __user *, lvec,
	345	compat_ulong_t, liovcnt,
	346	const struct compat_iovec __user *, rvec,
	347	compat_ulong_t, riovcnt,
	348	compat_ulong_t, flags)
fcf63409 CY	349	{
	350	return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
	351	riovcnt, flags, 0);
	352	}
	353
2f2728f6 HC	354	COMPAT_SYSCALL_DEFINE6(process_vm_writev, compat_pid_t, pid,
	355	const struct compat_iovec __user *, lvec,
	356	compat_ulong_t, liovcnt,
	357	const struct compat_iovec __user *, rvec,
	358	compat_ulong_t, riovcnt,
	359	compat_ulong_t, flags)
fcf63409 CY	360	{
	361	return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
	362	riovcnt, flags, 1);
	363	}
	364
	365	#endif