Commit 444ec524 authored by ZhangPeng's avatar ZhangPeng Committed by Ma Wupeng
Browse files

userswap: introduce UFFDIO_COPY_MODE_DIRECT_MAP to map without copying 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6CAIM



--------------------------------

Add a new UFFDIO_COPY mode UFFDIO_COPY_MODE_DIRECT_MAP to map physical
pages without copy_from_user().
We introduce uswap_unmap_anon_page() to unmap an anonymous page and
uswap_map_anon_page() to map page to src addr. We also introduce
mfill_atomic_pte_nocopy() to achieve zero copy by unmapping src_addr to the
physical page and establishing the mapping from dst_addr to the physical
page.

Signed-off-by: default avatarZhangPeng <zhangpeng362@huawei.com>
parent c098198d

fs/userfaultfd.c

+5 −4
Original line number Diff line number Diff line
@@ -27,13 +27,11 @@ 
#include <linux/ioctl.h>

#include <linux/security.h>

#include <linux/hugetlb.h>

#include <linux/userswap.h>



int sysctl_unprivileged_userfaultfd __read_mostly = 1;



static struct kmem_cache *userfaultfd_ctx_cachep __read_mostly;

#ifdef CONFIG_USERSWAP

int enable_userswap;

#endif



/*

 * Start with fault_pending_wqh and fault_wqh so they're more likely
@@ -1717,7 +1715,10 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx, 
	ret = -EINVAL;

	if (uffdio_copy.src + uffdio_copy.len <= uffdio_copy.src)

		goto out;

	if (uffdio_copy.mode & ~(UFFDIO_COPY_MODE_DONTWAKE|UFFDIO_COPY_MODE_WP))

	if (uffdio_copy.mode & ~(UFFDIO_COPY_MODE_DONTWAKE |

				 UFFDIO_COPY_MODE_WP |

				 IS_ENABLED(CONFIG_USERSWAP) ?

				 UFFDIO_COPY_MODE_DIRECT_MAP : 0))

		goto out;

	if (mmget_not_zero(ctx->mm)) {

		ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src,

include/linux/userfaultfd_k.h

+0 −3
Original line number Diff line number Diff line
@@ -31,9 +31,6 @@ 
#define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)



extern int sysctl_unprivileged_userfaultfd;

#ifdef CONFIG_USERSWAP

extern int enable_userswap;

#endif



extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason);

include/linux/userswap.h

0 → 100644
+28 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-or-later */

/*

 * Copyright (C) Huawei Technologies Co., Ltd. 2023. All rights reserved.

 */



#ifndef _LINUX_USERSWAP_H

#define _LINUX_USERSWAP_H



#ifdef CONFIG_USERSWAP



extern int enable_userswap;



int mfill_atomic_pte_nocopy(struct mm_struct *dst_mm,

			    pmd_t *dst_pmd,

			    struct vm_area_struct *dst_vma,

			    unsigned long dst_addr,

			    unsigned long src_addr);



static inline bool uswap_check_copy_mode(struct vm_area_struct *vma, __u64 mode)

{

	if (!(vma->vm_flags & VM_USWAP) && (mode & UFFDIO_COPY_MODE_DIRECT_MAP))

		return false;

	return true;

}



#endif /* CONFIG_USERSWAP */



#endif /* _LINUX_USERSWAP_H */

include/uapi/linux/userfaultfd.h

+1 −0
Original line number Diff line number Diff line
@@ -217,6 +217,7 @@ struct uffdio_copy { 
	 * according to the uffdio_register.ioctls.

	 */

#define UFFDIO_COPY_MODE_WP			((__u64)1<<1)

#define UFFDIO_COPY_MODE_DIRECT_MAP		((__u64)1<<10)

	__u64 mode;



	/*

mm/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -113,6 +113,7 @@ obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o 
obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o

obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o

obj-$(CONFIG_USERFAULTFD) += userfaultfd.o

obj-$(CONFIG_USERSWAP) += userswap.o

obj-$(CONFIG_IDLE_PAGE_TRACKING) += page_idle.o

obj-$(CONFIG_FRAME_VECTOR) += frame_vector.o

obj-$(CONFIG_DEBUG_PAGE_REF) += debug_page_ref.o