Commit faa3fdcd authored by Guo Fan's avatar Guo Fan Committed by Zheng Zengkai
Browse files

userswap: add a new flag 'MAP_REPLACE' for mmap() 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I40AXF


CVE: NA

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

To make sure there are no other userspace threads access the memory
region we are swapping out, we need unmmap the memory region, map it
to a new address and use the new address to perform the swapout. We add
a new flag 'MAP_REPLACE' for mmap() to unmap the pages of the input
parameter 'VA' and remap them to a new tmpVA.

Signed-off-by: default avatarGuo Fan <guofan5@huawei.com>
Signed-off-by: default avatarXiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: default avatarXiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: default avatartong tiangen <tongtiangen@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent c78eb5c1

fs/proc/task_mmu.c

+3 −0
Original line number Diff line number Diff line
@@ -661,6 +661,9 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma) 
		[ilog2(VM_PKEY_BIT4)]	= "",

#endif

#endif /* CONFIG_ARCH_HAS_PKEYS */

#ifdef CONFIG_USERSWAP

		[ilog2(VM_USWAP)]	= "us",

#endif

	};

	size_t i;

include/linux/mm.h

+5 −0
Original line number Diff line number Diff line
@@ -298,6 +298,11 @@ extern unsigned int kobjsize(const void *objp); 
#define VM_NOHUGEPAGE	0x40000000	/* MADV_NOHUGEPAGE marked this vma */

#define VM_MERGEABLE	0x80000000	/* KSM may merge identical pages */



#ifdef CONFIG_USERSWAP

/* bit[32:36] is the protection key of intel, so use a large value for VM_USWAP */

#define VM_USWAP      0x2000000000000000

#endif



#ifdef CONFIG_ARCH_USES_HIGH_VMA_FLAGS

#define VM_HIGH_ARCH_BIT_0	32	/* bit only usable on 64-bit architectures */

#define VM_HIGH_ARCH_BIT_1	33	/* bit only usable on 64-bit architectures */

include/linux/swap.h

+11 −1
Original line number Diff line number Diff line
@@ -53,6 +53,16 @@ static inline int current_is_kswapd(void) 
 * actions on faults.

 */



/*

 * Userswap entry type

 */

#ifdef CONFIG_USERSWAP

#define SWP_USERSWAP_NUM 1

#define SWP_USERSWAP_ENTRY (MAX_SWAPFILES+SWP_HWPOISON_NUM+SWP_MIGRATION_NUM+SWP_DEVICE_NUM)

#else

#define SWP_USERSWAP_NUM 0

#endif



/*

 * Unaddressable device memory support. See include/linux/hmm.h and

 * Documentation/vm/hmm.rst. Short description is we need struct pages for
@@ -93,7 +103,7 @@ static inline int current_is_kswapd(void) 


#define MAX_SWAPFILES \

	((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \

	SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)

	SWP_MIGRATION_NUM - SWP_HWPOISON_NUM - SWP_USERSWAP_NUM)



/*

 * Magic header for a swap area. The first part of the union is

include/trace/events/mmflags.h

+7 −0
Original line number Diff line number Diff line
@@ -137,6 +137,12 @@ IF_HAVE_PG_ARCH_2(PG_arch_2, "arch_2" ) 
#define IF_HAVE_VM_SOFTDIRTY(flag,name)

#endif



#ifdef CONFIG_USERSWAP

#define IF_HAVE_VM_USWAP(flag,name) {flag, name },

#else

#define IF_HAVE_VM_USWAP(flag,name)

#endif



#define __def_vmaflag_names						\

	{VM_READ,			"read"		},		\

	{VM_WRITE,			"write"		},		\
@@ -169,6 +175,7 @@ IF_HAVE_VM_SOFTDIRTY(VM_SOFTDIRTY, "softdirty" ) \ 
	{VM_MIXEDMAP,			"mixedmap"	},		\

	{VM_HUGEPAGE,			"hugepage"	},		\

	{VM_NOHUGEPAGE,			"nohugepage"	},		\

IF_HAVE_VM_USWAP(VM_USWAP,		"userswap"	)		\

	{VM_MERGEABLE,			"mergeable"	}		\



#define show_vma_flags(flags)						\

include/uapi/asm-generic/mman-common.h

+2 −0
Original line number Diff line number Diff line
@@ -30,6 +30,8 @@ 
#define MAP_SYNC		0x080000 /* perform synchronous page faults for the mapping */

#define MAP_FIXED_NOREPLACE	0x100000	/* MAP_FIXED which doesn't unmap underlying mapping */



#define MAP_REPLACE		0x1000000



#define MAP_UNINITIALIZED 0x4000000	/* For anonymous mmap, memory could be

					 * uninitialized */