add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/mm/process_vm_access.c
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..
@@ -1,26 +1,20 @@
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+// SPDX-License-Identifier: GPL-2.0-or-later
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 /*
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  * linux/mm/process_vm_access.c
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  *
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  * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp.
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- *
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- * This program is free software; you can redistribute it and/or
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- * modify it under the terms of the GNU General Public License
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- * as published by the Free Software Foundation; either version
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- * 2 of the License, or (at your option) any later version.
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  */
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+#include <linux/compat.h>
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 #include <linux/mm.h>
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 #include <linux/uio.h>
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 #include <linux/sched.h>
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+#include <linux/compat.h>
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 #include <linux/sched/mm.h>
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 #include <linux/highmem.h>
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 #include <linux/ptrace.h>
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 #include <linux/slab.h>
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 #include <linux/syscalls.h>
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-
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-#ifdef CONFIG_COMPAT
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-#include <linux/compat.h>
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-#endif
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18
 
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 /**
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  * process_vm_rw_pages - read/write pages from task specified
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@@ -46,12 +40,11 @@
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 		if (copy > len)
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 			copy = len;
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-		if (vm_write) {
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+		if (vm_write)
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 			copied = copy_page_from_iter(page, offset, copy, iter);
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-			set_page_dirty_lock(page);
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-		} else {
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+		else
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 			copied = copy_page_to_iter(page, offset, copy, iter);
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-		}
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+
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 		len -= copied;
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 		if (copied < copy && iov_iter_count(iter))
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 			return -EFAULT;
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..
@@ -100,7 +93,7 @@
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 		flags |= FOLL_WRITE;
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 	while (!rc && nr_pages && iov_iter_count(iter)) {
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-		int pages = min(nr_pages, max_pages_per_loop);
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+		int pinned_pages = min(nr_pages, max_pages_per_loop);
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 		int locked = 1;
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 		size_t bytes;
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@@ -109,15 +102,16 @@
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 		 * access remotely because task/mm might not
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 		 * current/current->mm
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 		 */
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-		down_read(&mm->mmap_sem);
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-		pages = get_user_pages_remote(task, mm, pa, pages, flags,
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-					      process_pages, NULL, &locked);
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+		mmap_read_lock(mm);
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+		pinned_pages = pin_user_pages_remote(mm, pa, pinned_pages,
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+						     flags, process_pages,
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+						     NULL, &locked);
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 		if (locked)
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-			up_read(&mm->mmap_sem);
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-		if (pages <= 0)
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+			mmap_read_unlock(mm);
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+		if (pinned_pages <= 0)
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 			return -EFAULT;
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-		bytes = pages * PAGE_SIZE - start_offset;
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+		bytes = pinned_pages * PAGE_SIZE - start_offset;
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 		if (bytes > len)
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 			bytes = len;
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@@ -126,10 +120,12 @@
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 					 vm_write);
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 		len -= bytes;
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 		start_offset = 0;
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-		nr_pages -= pages;
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-		pa += pages * PAGE_SIZE;
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-		while (pages)
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-			put_page(process_pages[--pages]);
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+		nr_pages -= pinned_pages;
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+		pa += pinned_pages * PAGE_SIZE;
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+
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+		/* If vm_write is set, the pages need to be made dirty: */
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+		unpin_user_pages_dirty_lock(process_pages, pinned_pages,
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+					    vm_write);
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 	}
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 	return rc;
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@@ -208,7 +204,7 @@
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 	if (!mm || IS_ERR(mm)) {
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 		rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
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 		/*
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-		 * Explicitly map EACCES to EPERM as EPERM is a more a
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+		 * Explicitly map EACCES to EPERM as EPERM is a more
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 		 * appropriate error code for process_vw_readv/writev
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 		 */
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 		if (rc == -EACCES)
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@@ -278,20 +274,18 @@
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 	if (rc < 0)
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 		return rc;
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 	if (!iov_iter_count(&iter))
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-		goto free_iovecs;
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-
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-	rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV,
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-				   iovstack_r, &iov_r);
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-	if (rc <= 0)
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-		goto free_iovecs;
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-
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+		goto free_iov_l;
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+	iov_r = iovec_from_user(rvec, riovcnt, UIO_FASTIOV, iovstack_r,
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+				in_compat_syscall());
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+	if (IS_ERR(iov_r)) {
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+		rc = PTR_ERR(iov_r);
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+		goto free_iov_l;
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+	}
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 	rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
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-
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-free_iovecs:
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 	if (iov_r != iovstack_r)
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 		kfree(iov_r);
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+free_iov_l:
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 	kfree(iov_l);
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-
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 	return rc;
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 }
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@@ -309,68 +303,3 @@
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 {
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 	return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1);
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 }
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-
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-#ifdef CONFIG_COMPAT
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-
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-static ssize_t
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-compat_process_vm_rw(compat_pid_t pid,
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-		     const struct compat_iovec __user *lvec,
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-		     unsigned long liovcnt,
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-		     const struct compat_iovec __user *rvec,
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-		     unsigned long riovcnt,
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-		     unsigned long flags, int vm_write)
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-{
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-	struct iovec iovstack_l[UIO_FASTIOV];
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-	struct iovec iovstack_r[UIO_FASTIOV];
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-	struct iovec *iov_l = iovstack_l;
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-	struct iovec *iov_r = iovstack_r;
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-	struct iov_iter iter;
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-	ssize_t rc = -EFAULT;
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-	int dir = vm_write ? WRITE : READ;
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-
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-	if (flags != 0)
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-		return -EINVAL;
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-
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-	rc = compat_import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
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-	if (rc < 0)
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-		return rc;
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-	if (!iov_iter_count(&iter))
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-		goto free_iovecs;
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-	rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt,
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-					  UIO_FASTIOV, iovstack_r,
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-					  &iov_r);
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-	if (rc <= 0)
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-		goto free_iovecs;
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-
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-	rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
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-
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-free_iovecs:
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-	if (iov_r != iovstack_r)
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-		kfree(iov_r);
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-	kfree(iov_l);
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-	return rc;
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-}
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-
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-COMPAT_SYSCALL_DEFINE6(process_vm_readv, compat_pid_t, pid,
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-		       const struct compat_iovec __user *, lvec,
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-		       compat_ulong_t, liovcnt,
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-		       const struct compat_iovec __user *, rvec,
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-		       compat_ulong_t, riovcnt,
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-		       compat_ulong_t, flags)
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-{
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-	return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
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-				    riovcnt, flags, 0);
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-}
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-
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-COMPAT_SYSCALL_DEFINE6(process_vm_writev, compat_pid_t, pid,
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-		       const struct compat_iovec __user *, lvec,
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-		       compat_ulong_t, liovcnt,
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-		       const struct compat_iovec __user *, rvec,
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-		       compat_ulong_t, riovcnt,
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-		       compat_ulong_t, flags)
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-{
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-	return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
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-				    riovcnt, flags, 1);
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-}
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-
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-#endif