Eric Lee / smarc-fsl-linux-kernel

mm_types.h 24.9 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_MM_TYPES_H
#define _LINUX_MM_TYPES_H

#include <linux/mm_types_task.h>

#include <linux/auxvec.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/rbtree.h>
#include <linux/rwsem.h>
#include <linux/completion.h>
#include <linux/cpumask.h>
#include <linux/uprobes.h>
#include <linux/page-flags-layout.h>
#include <linux/workqueue.h>
#include <linux/seqlock.h>

#include <asm/mmu.h>

#ifndef AT_VECTOR_SIZE_ARCH
#define AT_VECTOR_SIZE_ARCH 0
#endif
#define AT_VECTOR_SIZE (2*(AT_VECTOR_SIZE_ARCH + AT_VECTOR_SIZE_BASE + 1))


struct address_space;
struct mem_cgroup;

/*
 * Each physical page in the system has a struct page associated with
 * it to keep track of whatever it is we are using the page for at the
 * moment. Note that we have no way to track which tasks are using
 * a page, though if it is a pagecache page, rmap structures can tell us
 * who is mapping it.
 *
 * If you allocate the page using alloc_pages(), you can use some of the
 * space in struct page for your own purposes.  The five words in the main
 * union are available, except for bit 0 of the first word which must be
 * kept clear.  Many users use this word to store a pointer to an object
 * which is guaranteed to be aligned.  If you use the same storage as
 * page->mapping, you must restore it to NULL before freeing the page.
 *
 * If your page will not be mapped to userspace, you can also use the four
 * bytes in the mapcount union, but you must call page_mapcount_reset()
 * before freeing it.
 *
 * If you want to use the refcount field, it must be used in such a way
 * that other CPUs temporarily incrementing and then decrementing the
 * refcount does not cause problems.  On receiving the page from
 * alloc_pages(), the refcount will be positive.
 *
 * If you allocate pages of order > 0, you can use some of the fields
 * in each subpage, but you may need to restore some of their values
 * afterwards.
 *
 * SLUB uses cmpxchg_double() to atomically update its freelist and
 * counters.  That requires that freelist & counters be adjacent and
 * double-word aligned.  We align all struct pages to double-word
 * boundaries, and ensure that 'freelist' is aligned within the
 * struct.
 */
#ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
#define _struct_page_alignment	__aligned(2 * sizeof(unsigned long))
#else
#define _struct_page_alignment
#endif

struct page {
	unsigned long flags;		/* Atomic flags, some possibly
					 * updated asynchronously */
	/*
	 * Five words (20/40 bytes) are available in this union.
	 * WARNING: bit 0 of the first word is used for PageTail(). That
	 * means the other users of this union MUST NOT use the bit to
	 * avoid collision and false-positive PageTail().
	 */
	union {
		struct {	/* Page cache and anonymous pages */
			/**
			 * @lru: Pageout list, eg. active_list protected by
			 * pgdat->lru_lock.  Sometimes used as a generic list
			 * by the page owner.
			 */
			struct list_head lru;
			/* See page-flags.h for PAGE_MAPPING_FLAGS */
			struct address_space *mapping;
			pgoff_t index;		/* Our offset within mapping. */
			/**
			 * @private: Mapping-private opaque data.
			 * Usually used for buffer_heads if PagePrivate.
			 * Used for swp_entry_t if PageSwapCache.
			 * Indicates order in the buddy system if PageBuddy.
			 */
			unsigned long private;
		};
		struct {	/* page_pool used by netstack */
			/**
			 * @dma_addr: might require a 64-bit value even on
			 * 32-bit architectures.
			 */
			dma_addr_t dma_addr;
		};
		struct {	/* slab, slob and slub */
			union {
				struct list_head slab_list;
				struct {	/* Partial pages */
					struct page *next;
#ifdef CONFIG_64BIT
					int pages;	/* Nr of pages left */
					int pobjects;	/* Approximate count */
#else
					short int pages;
					short int pobjects;
#endif
				};
			};
			struct kmem_cache *slab_cache; /* not slob */
			/* Double-word boundary */
			void *freelist;		/* first free object */
			union {
				void *s_mem;	/* slab: first object */
				unsigned long counters;		/* SLUB */
				struct {			/* SLUB */
					unsigned inuse:16;
					unsigned objects:15;
					unsigned frozen:1;
				};
			};
		};
		struct {	/* Tail pages of compound page */
			unsigned long compound_head;	/* Bit zero is set */

			/* First tail page only */
			unsigned char compound_dtor;
			unsigned char compound_order;
			atomic_t compound_mapcount;
			unsigned int compound_nr; /* 1 << compound_order */
		};
		struct {	/* Second tail page of compound page */
			unsigned long _compound_pad_1;	/* compound_head */
			atomic_t hpage_pinned_refcount;
			/* For both global and memcg */
			struct list_head deferred_list;
		};
		struct {	/* Page table pages */
			unsigned long _pt_pad_1;	/* compound_head */
			pgtable_t pmd_huge_pte; /* protected by page->ptl */
			unsigned long _pt_pad_2;	/* mapping */
			union {
				struct mm_struct *pt_mm; /* x86 pgds only */
				atomic_t pt_frag_refcount; /* powerpc */
			};
#if ALLOC_SPLIT_PTLOCKS
			spinlock_t *ptl;
#else
			spinlock_t ptl;
#endif
		};
		struct {	/* ZONE_DEVICE pages */
			/** @pgmap: Points to the hosting device page map. */
			struct dev_pagemap *pgmap;
			void *zone_device_data;
			/*
			 * ZONE_DEVICE private pages are counted as being
			 * mapped so the next 3 words hold the mapping, index,
			 * and private fields from the source anonymous or
			 * page cache page while the page is migrated to device
			 * private memory.
			 * ZONE_DEVICE MEMORY_DEVICE_FS_DAX pages also
			 * use the mapping, index, and private fields when
			 * pmem backed DAX files are mapped.
			 */
		};

		/** @rcu_head: You can use this to free a page by RCU. */
		struct rcu_head rcu_head;
	};

	union {		/* This union is 4 bytes in size. */
		/*
		 * If the page can be mapped to userspace, encodes the number
		 * of times this page is referenced by a page table.
		 */
		atomic_t _mapcount;

		/*
		 * If the page is neither PageSlab nor mappable to userspace,
		 * the value stored here may help determine what this page
		 * is used for.  See page-flags.h for a list of page types
		 * which are currently stored here.
		 */
		unsigned int page_type;

		unsigned int active;		/* SLAB */
		int units;			/* SLOB */
	};

	/* Usage count. *DO NOT USE DIRECTLY*. See page_ref.h */
	atomic_t _refcount;

#ifdef CONFIG_MEMCG
	union {
		struct mem_cgroup *mem_cgroup;
		struct obj_cgroup **obj_cgroups;
	};
#endif

	/*
	 * On machines where all RAM is mapped into kernel address space,
	 * we can simply calculate the virtual address. On machines with
	 * highmem some memory is mapped into kernel virtual memory
	 * dynamically, so we need a place to store that address.
	 * Note that this field could be 16 bits on x86 ... ;)
	 *
	 * Architectures with slow multiplication can define
	 * WANT_PAGE_VIRTUAL in asm/page.h
	 */
#if defined(WANT_PAGE_VIRTUAL)
	void *virtual;			/* Kernel virtual address (NULL if
					   not kmapped, ie. highmem) */
#endif /* WANT_PAGE_VIRTUAL */

#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
	int _last_cpupid;
#endif
} _struct_page_alignment;

static inline atomic_t *compound_mapcount_ptr(struct page *page)
{
	return &page[1].compound_mapcount;
}

static inline atomic_t *compound_pincount_ptr(struct page *page)
{
	return &page[2].hpage_pinned_refcount;
}

/*
 * Used for sizing the vmemmap region on some architectures
 */
#define STRUCT_PAGE_MAX_SHIFT	(order_base_2(sizeof(struct page)))

#define PAGE_FRAG_CACHE_MAX_SIZE	__ALIGN_MASK(32768, ~PAGE_MASK)
#define PAGE_FRAG_CACHE_MAX_ORDER	get_order(PAGE_FRAG_CACHE_MAX_SIZE)

#define page_private(page)		((page)->private)

static inline void set_page_private(struct page *page, unsigned long private)
{
	page->private = private;
}

struct page_frag_cache {
	void * va;
#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
	__u16 offset;
	__u16 size;
#else
	__u32 offset;
#endif
	/* we maintain a pagecount bias, so that we dont dirty cache line
	 * containing page->_refcount every time we allocate a fragment.
	 */
	unsigned int		pagecnt_bias;
	bool pfmemalloc;
};

typedef unsigned long vm_flags_t;

/*
 * A region containing a mapping of a non-memory backed file under NOMMU
 * conditions.  These are held in a global tree and are pinned by the VMAs that
 * map parts of them.
 */
struct vm_region {
	struct rb_node	vm_rb;		/* link in global region tree */
	vm_flags_t	vm_flags;	/* VMA vm_flags */
	unsigned long	vm_start;	/* start address of region */
	unsigned long	vm_end;		/* region initialised to here */
	unsigned long	vm_top;		/* region allocated to here */
	unsigned long	vm_pgoff;	/* the offset in vm_file corresponding to vm_start */
	struct file	*vm_file;	/* the backing file or NULL */

	int		vm_usage;	/* region usage count (access under nommu_region_sem) */
	bool		vm_icache_flushed : 1; /* true if the icache has been flushed for
						* this region */
};

#ifdef CONFIG_USERFAULTFD
#define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) { NULL, })
struct vm_userfaultfd_ctx {
	struct userfaultfd_ctx *ctx;
};
#else /* CONFIG_USERFAULTFD */
#define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) {})
struct vm_userfaultfd_ctx {};
#endif /* CONFIG_USERFAULTFD */

/*
 * This struct describes a virtual memory area. There is one of these
 * per VM-area/task. A VM area is any part of the process virtual memory
 * space that has a special rule for the page-fault handlers (ie a shared
 * library, the executable area etc).
 */
struct vm_area_struct {
	/* The first cache line has the info for VMA tree walking. */

	unsigned long vm_start;		/* Our start address within vm_mm. */
	unsigned long vm_end;		/* The first byte after our end address
					   within vm_mm. */

	/* linked list of VM areas per task, sorted by address */
	struct vm_area_struct *vm_next, *vm_prev;

	struct rb_node vm_rb;

	/*
	 * Largest free memory gap in bytes to the left of this VMA.
	 * Either between this VMA and vma->vm_prev, or between one of the
	 * VMAs below us in the VMA rbtree and its ->vm_prev. This helps
	 * get_unmapped_area find a free area of the right size.
	 */
	unsigned long rb_subtree_gap;

	/* Second cache line starts here. */

	struct mm_struct *vm_mm;	/* The address space we belong to. */

	/*
	 * Access permissions of this VMA.
	 * See vmf_insert_mixed_prot() for discussion.
	 */
	pgprot_t vm_page_prot;
	unsigned long vm_flags;		/* Flags, see mm.h. */

	/*
	 * For areas with an address space and backing store,
	 * linkage into the address_space->i_mmap interval tree.
	 *
	 * For private anonymous mappings, a pointer to a null terminated string
	 * in the user process containing the name given to the vma, or NULL
	 * if unnamed.
	 */
	union {
		struct {
			struct rb_node rb;
			unsigned long rb_subtree_last;
		} shared;
		const char __user *anon_name;
	};

	/*
	 * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma
	 * list, after a COW of one of the file pages.	A MAP_SHARED vma
	 * can only be in the i_mmap tree.  An anonymous MAP_PRIVATE, stack
	 * or brk vma (with NULL file) can only be in an anon_vma list.
	 */
	struct list_head anon_vma_chain; /* Serialized by mmap_lock &
					  * page_table_lock */
	struct anon_vma *anon_vma;	/* Serialized by page_table_lock */

	/* Function pointers to deal with this struct. */
	const struct vm_operations_struct *vm_ops;

	/* Information about our backing store: */
	unsigned long vm_pgoff;		/* Offset (within vm_file) in PAGE_SIZE
					   units */
	struct file * vm_file;		/* File we map to (can be NULL). */
	void * vm_private_data;		/* was vm_pte (shared mem) */

#ifdef CONFIG_SWAP
	atomic_long_t swap_readahead_info;
#endif
#ifndef CONFIG_MMU
	struct vm_region *vm_region;	/* NOMMU mapping region */
#endif
#ifdef CONFIG_NUMA
	struct mempolicy *vm_policy;	/* NUMA policy for the VMA */
#endif
	struct vm_userfaultfd_ctx vm_userfaultfd_ctx;
} __randomize_layout;

struct core_thread {
	struct task_struct *task;
	struct core_thread *next;
};

struct core_state {
	atomic_t nr_threads;
	struct core_thread dumper;
	struct completion startup;
};

struct kioctx_table;
struct mm_struct {
	struct {
		struct vm_area_struct *mmap;		/* list of VMAs */
		struct rb_root mm_rb;
		u64 vmacache_seqnum;                   /* per-thread vmacache */
#ifdef CONFIG_MMU
		unsigned long (*get_unmapped_area) (struct file *filp,
				unsigned long addr, unsigned long len,
				unsigned long pgoff, unsigned long flags);
#endif
		unsigned long mmap_base;	/* base of mmap area */
		unsigned long mmap_legacy_base;	/* base of mmap area in bottom-up allocations */
#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
		/* Base adresses for compatible mmap() */
		unsigned long mmap_compat_base;
		unsigned long mmap_compat_legacy_base;
#endif
		unsigned long task_size;	/* size of task vm space */
		unsigned long highest_vm_end;	/* highest vma end address */
		pgd_t * pgd;

#ifdef CONFIG_MEMBARRIER
		/**
		 * @membarrier_state: Flags controlling membarrier behavior.
		 *
		 * This field is close to @pgd to hopefully fit in the same
		 * cache-line, which needs to be touched by switch_mm().
		 */
		atomic_t membarrier_state;
#endif

		/**
		 * @mm_users: The number of users including userspace.
		 *
		 * Use mmget()/mmget_not_zero()/mmput() to modify. When this
		 * drops to 0 (i.e. when the task exits and there are no other
		 * temporary reference holders), we also release a reference on
		 * @mm_count (which may then free the &struct mm_struct if
		 * @mm_count also drops to 0).
		 */
		atomic_t mm_users;

		/**
		 * @mm_count: The number of references to &struct mm_struct
		 * (@mm_users count as 1).
		 *
		 * Use mmgrab()/mmdrop() to modify. When this drops to 0, the
		 * &struct mm_struct is freed.
		 */
		atomic_t mm_count;

		/**
		 * @has_pinned: Whether this mm has pinned any pages.  This can
		 * be either replaced in the future by @pinned_vm when it
		 * becomes stable, or grow into a counter on its own. We're
		 * aggresive on this bit now - even if the pinned pages were
		 * unpinned later on, we'll still keep this bit set for the
		 * lifecycle of this mm just for simplicity.
		 */
		atomic_t has_pinned;

		/**
		 * @write_protect_seq: Locked when any thread is write
		 * protecting pages mapped by this mm to enforce a later COW,
		 * for instance during page table copying for fork().
		 */
		seqcount_t write_protect_seq;

#ifdef CONFIG_MMU
		atomic_long_t pgtables_bytes;	/* PTE page table pages */
#endif
		int map_count;			/* number of VMAs */

		spinlock_t page_table_lock; /* Protects page tables and some
					     * counters
					     */
		struct rw_semaphore mmap_lock;

		struct list_head mmlist; /* List of maybe swapped mm's.	These
					  * are globally strung together off
					  * init_mm.mmlist, and are protected
					  * by mmlist_lock
					  */


		unsigned long hiwater_rss; /* High-watermark of RSS usage */
		unsigned long hiwater_vm;  /* High-water virtual memory usage */

		unsigned long total_vm;	   /* Total pages mapped */
		unsigned long locked_vm;   /* Pages that have PG_mlocked set */
		atomic64_t    pinned_vm;   /* Refcount permanently increased */
		unsigned long data_vm;	   /* VM_WRITE & ~VM_SHARED & ~VM_STACK */
		unsigned long exec_vm;	   /* VM_EXEC & ~VM_WRITE & ~VM_STACK */
		unsigned long stack_vm;	   /* VM_STACK */
		unsigned long def_flags;

		spinlock_t arg_lock; /* protect the below fields */
		unsigned long start_code, end_code, start_data, end_data;
		unsigned long start_brk, brk, start_stack;
		unsigned long arg_start, arg_end, env_start, env_end;

		unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */

		/*
		 * Special counters, in some configurations protected by the
		 * page_table_lock, in other configurations by being atomic.
		 */
		struct mm_rss_stat rss_stat;

		struct linux_binfmt *binfmt;

		/* Architecture-specific MM context */
		mm_context_t context;

		unsigned long flags; /* Must use atomic bitops to access */

		struct core_state *core_state; /* coredumping support */

#ifdef CONFIG_AIO
		spinlock_t			ioctx_lock;
		struct kioctx_table __rcu	*ioctx_table;
#endif
#ifdef CONFIG_MEMCG
		/*
		 * "owner" points to a task that is regarded as the canonical
		 * user/owner of this mm. All of the following must be true in
		 * order for it to be changed:
		 *
		 * current == mm->owner
		 * current->mm != mm
		 * new_owner->mm == mm
		 * new_owner->alloc_lock is held
		 */
		struct task_struct __rcu *owner;
#endif
		struct user_namespace *user_ns;

		/* store ref to file /proc/<pid>/exe symlink points to */
		struct file __rcu *exe_file;
#ifdef CONFIG_MMU_NOTIFIER
		struct mmu_notifier_subscriptions *notifier_subscriptions;
#endif
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
		pgtable_t pmd_huge_pte; /* protected by page_table_lock */
#endif
#ifdef CONFIG_NUMA_BALANCING
		/*
		 * numa_next_scan is the next time that the PTEs will be marked
		 * pte_numa. NUMA hinting faults will gather statistics and
		 * migrate pages to new nodes if necessary.
		 */
		unsigned long numa_next_scan;

		/* Restart point for scanning and setting pte_numa */
		unsigned long numa_scan_offset;

		/* numa_scan_seq prevents two threads setting pte_numa */
		int numa_scan_seq;
#endif
		/*
		 * An operation with batched TLB flushing is going on. Anything
		 * that can move process memory needs to flush the TLB when
		 * moving a PROT_NONE or PROT_NUMA mapped page.
		 */
		atomic_t tlb_flush_pending;
#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
		/* See flush_tlb_batched_pending() */
		bool tlb_flush_batched;
#endif
		struct uprobes_state uprobes_state;
#ifdef CONFIG_HUGETLB_PAGE
		atomic_long_t hugetlb_usage;
#endif
		struct work_struct async_put_work;

#ifdef CONFIG_IOMMU_SUPPORT
		u32 pasid;
#endif
	} __randomize_layout;

	/*
	 * The mm_cpumask needs to be at the end of mm_struct, because it
	 * is dynamically sized based on nr_cpu_ids.
	 */
	unsigned long cpu_bitmap[];
};

extern struct mm_struct init_mm;

/* Pointer magic because the dynamic array size confuses some compilers. */
static inline void mm_init_cpumask(struct mm_struct *mm)
{
	unsigned long cpu_bitmap = (unsigned long)mm;

	cpu_bitmap += offsetof(struct mm_struct, cpu_bitmap);
	cpumask_clear((struct cpumask *)cpu_bitmap);
}

/* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
{
	return (struct cpumask *)&mm->cpu_bitmap;
}

struct mmu_gather;
extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
				unsigned long start, unsigned long end);
extern void tlb_finish_mmu(struct mmu_gather *tlb,
				unsigned long start, unsigned long end);

static inline void init_tlb_flush_pending(struct mm_struct *mm)
{
	atomic_set(&mm->tlb_flush_pending, 0);
}

static inline void inc_tlb_flush_pending(struct mm_struct *mm)
{
	atomic_inc(&mm->tlb_flush_pending);
	/*
	 * The only time this value is relevant is when there are indeed pages
	 * to flush. And we'll only flush pages after changing them, which
	 * requires the PTL.
	 *
	 * So the ordering here is:
	 *
	 *	atomic_inc(&mm->tlb_flush_pending);
	 *	spin_lock(&ptl);
	 *	...
	 *	set_pte_at();
	 *	spin_unlock(&ptl);
	 *
	 *				spin_lock(&ptl)
	 *				mm_tlb_flush_pending();
	 *				....
	 *				spin_unlock(&ptl);
	 *
	 *	flush_tlb_range();
	 *	atomic_dec(&mm->tlb_flush_pending);
	 *
	 * Where the increment if constrained by the PTL unlock, it thus
	 * ensures that the increment is visible if the PTE modification is
	 * visible. After all, if there is no PTE modification, nobody cares
	 * about TLB flushes either.
	 *
	 * This very much relies on users (mm_tlb_flush_pending() and
	 * mm_tlb_flush_nested()) only caring about _specific_ PTEs (and
	 * therefore specific PTLs), because with SPLIT_PTE_PTLOCKS and RCpc
	 * locks (PPC) the unlock of one doesn't order against the lock of
	 * another PTL.
	 *
	 * The decrement is ordered by the flush_tlb_range(), such that
	 * mm_tlb_flush_pending() will not return false unless all flushes have
	 * completed.
	 */
}

static inline void dec_tlb_flush_pending(struct mm_struct *mm)
{
	/*
	 * See inc_tlb_flush_pending().
	 *
	 * This cannot be smp_mb__before_atomic() because smp_mb() simply does
	 * not order against TLB invalidate completion, which is what we need.
	 *
	 * Therefore we must rely on tlb_flush_*() to guarantee order.
	 */
	atomic_dec(&mm->tlb_flush_pending);
}

static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
{
	/*
	 * Must be called after having acquired the PTL; orders against that
	 * PTLs release and therefore ensures that if we observe the modified
	 * PTE we must also observe the increment from inc_tlb_flush_pending().
	 *
	 * That is, it only guarantees to return true if there is a flush
	 * pending for _this_ PTL.
	 */
	return atomic_read(&mm->tlb_flush_pending);
}

static inline bool mm_tlb_flush_nested(struct mm_struct *mm)
{
	/*
	 * Similar to mm_tlb_flush_pending(), we must have acquired the PTL
	 * for which there is a TLB flush pending in order to guarantee
	 * we've seen both that PTE modification and the increment.
	 *
	 * (no requirement on actually still holding the PTL, that is irrelevant)
	 */
	return atomic_read(&mm->tlb_flush_pending) > 1;
}

struct vm_fault;

/**
 * typedef vm_fault_t - Return type for page fault handlers.
 *
 * Page fault handlers return a bitmask of %VM_FAULT values.
 */
typedef __bitwise unsigned int vm_fault_t;

/**
 * enum vm_fault_reason - Page fault handlers return a bitmask of
 * these values to tell the core VM what happened when handling the
 * fault. Used to decide whether a process gets delivered SIGBUS or
 * just gets major/minor fault counters bumped up.
 *
 * @VM_FAULT_OOM:		Out Of Memory
 * @VM_FAULT_SIGBUS:		Bad access
 * @VM_FAULT_MAJOR:		Page read from storage
 * @VM_FAULT_WRITE:		Special case for get_user_pages
 * @VM_FAULT_HWPOISON:		Hit poisoned small page
 * @VM_FAULT_HWPOISON_LARGE:	Hit poisoned large page. Index encoded
 *				in upper bits
 * @VM_FAULT_SIGSEGV:		segmentation fault
 * @VM_FAULT_NOPAGE:		->fault installed the pte, not return page
 * @VM_FAULT_LOCKED:		->fault locked the returned page
 * @VM_FAULT_RETRY:		->fault blocked, must retry
 * @VM_FAULT_FALLBACK:		huge page fault failed, fall back to small
 * @VM_FAULT_DONE_COW:		->fault has fully handled COW
 * @VM_FAULT_NEEDDSYNC:		->fault did not modify page tables and needs
 *				fsync() to complete (for synchronous page faults
 *				in DAX)
 * @VM_FAULT_HINDEX_MASK:	mask HINDEX value
 *
 */
enum vm_fault_reason {
	VM_FAULT_OOM            = (__force vm_fault_t)0x000001,
	VM_FAULT_SIGBUS         = (__force vm_fault_t)0x000002,
	VM_FAULT_MAJOR          = (__force vm_fault_t)0x000004,
	VM_FAULT_WRITE          = (__force vm_fault_t)0x000008,
	VM_FAULT_HWPOISON       = (__force vm_fault_t)0x000010,
	VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020,
	VM_FAULT_SIGSEGV        = (__force vm_fault_t)0x000040,
	VM_FAULT_NOPAGE         = (__force vm_fault_t)0x000100,
	VM_FAULT_LOCKED         = (__force vm_fault_t)0x000200,
	VM_FAULT_RETRY          = (__force vm_fault_t)0x000400,
	VM_FAULT_FALLBACK       = (__force vm_fault_t)0x000800,
	VM_FAULT_DONE_COW       = (__force vm_fault_t)0x001000,
	VM_FAULT_NEEDDSYNC      = (__force vm_fault_t)0x002000,
	VM_FAULT_HINDEX_MASK    = (__force vm_fault_t)0x0f0000,
};

/* Encode hstate index for a hwpoisoned large page */
#define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16))
#define VM_FAULT_GET_HINDEX(x) (((__force unsigned int)(x) >> 16) & 0xf)

#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS |	\
			VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON |	\
			VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)

#define VM_FAULT_RESULT_TRACE \
	{ VM_FAULT_OOM,                 "OOM" },	\
	{ VM_FAULT_SIGBUS,              "SIGBUS" },	\
	{ VM_FAULT_MAJOR,               "MAJOR" },	\
	{ VM_FAULT_WRITE,               "WRITE" },	\
	{ VM_FAULT_HWPOISON,            "HWPOISON" },	\
	{ VM_FAULT_HWPOISON_LARGE,      "HWPOISON_LARGE" },	\
	{ VM_FAULT_SIGSEGV,             "SIGSEGV" },	\
	{ VM_FAULT_NOPAGE,              "NOPAGE" },	\
	{ VM_FAULT_LOCKED,              "LOCKED" },	\
	{ VM_FAULT_RETRY,               "RETRY" },	\
	{ VM_FAULT_FALLBACK,            "FALLBACK" },	\
	{ VM_FAULT_DONE_COW,            "DONE_COW" },	\
	{ VM_FAULT_NEEDDSYNC,           "NEEDDSYNC" }

struct vm_special_mapping {
	const char *name;	/* The name, e.g. "[vdso]". */

	/*
	 * If .fault is not provided, this points to a
	 * NULL-terminated array of pages that back the special mapping.
	 *
	 * This must not be NULL unless .fault is provided.
	 */
	struct page **pages;

	/*
	 * If non-NULL, then this is called to resolve page faults
	 * on the special mapping.  If used, .pages is not checked.
	 */
	vm_fault_t (*fault)(const struct vm_special_mapping *sm,
				struct vm_area_struct *vma,
				struct vm_fault *vmf);

	int (*mremap)(const struct vm_special_mapping *sm,
		     struct vm_area_struct *new_vma);
};

enum tlb_flush_reason {
	TLB_FLUSH_ON_TASK_SWITCH,
	TLB_REMOTE_SHOOTDOWN,
	TLB_LOCAL_SHOOTDOWN,
	TLB_LOCAL_MM_SHOOTDOWN,
	TLB_REMOTE_SEND_IPI,
	NR_TLB_FLUSH_REASONS,
};

 /*
  * A swap entry has to fit into a "unsigned long", as the entry is hidden
  * in the "index" field of the swapper address space.
  */
typedef struct {
	unsigned long val;
} swp_entry_t;

/* Return the name for an anonymous mapping or NULL for a file-backed mapping */
static inline const char __user *vma_get_anon_name(struct vm_area_struct *vma)
{
	if (vma->vm_file)
		return NULL;

	return vma->anon_name;
}

#endif /* _LINUX_MM_TYPES_H */