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TOMOYO Linux Cross Reference
Linux/include/linux/mm_types.h

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  1 /* SPDX-License-Identifier: GPL-2.0 */
  2 #ifndef _LINUX_MM_TYPES_H
  3 #define _LINUX_MM_TYPES_H
  4 
  5 #include <linux/mm_types_task.h>
  6 
  7 #include <linux/auxvec.h>
  8 #include <linux/list.h>
  9 #include <linux/spinlock.h>
 10 #include <linux/rbtree.h>
 11 #include <linux/rwsem.h>
 12 #include <linux/completion.h>
 13 #include <linux/cpumask.h>
 14 #include <linux/uprobes.h>
 15 #include <linux/page-flags-layout.h>
 16 #include <linux/workqueue.h>
 17 
 18 #include <asm/mmu.h>
 19 
 20 #ifndef AT_VECTOR_SIZE_ARCH
 21 #define AT_VECTOR_SIZE_ARCH 0
 22 #endif
 23 #define AT_VECTOR_SIZE (2*(AT_VECTOR_SIZE_ARCH + AT_VECTOR_SIZE_BASE + 1))
 24 
 25 
 26 struct address_space;
 27 struct mem_cgroup;
 28 struct hmm;
 29 
 30 /*
 31  * Each physical page in the system has a struct page associated with
 32  * it to keep track of whatever it is we are using the page for at the
 33  * moment. Note that we have no way to track which tasks are using
 34  * a page, though if it is a pagecache page, rmap structures can tell us
 35  * who is mapping it.
 36  *
 37  * If you allocate the page using alloc_pages(), you can use some of the
 38  * space in struct page for your own purposes.  The five words in the main
 39  * union are available, except for bit 0 of the first word which must be
 40  * kept clear.  Many users use this word to store a pointer to an object
 41  * which is guaranteed to be aligned.  If you use the same storage as
 42  * page->mapping, you must restore it to NULL before freeing the page.
 43  *
 44  * If your page will not be mapped to userspace, you can also use the four
 45  * bytes in the mapcount union, but you must call page_mapcount_reset()
 46  * before freeing it.
 47  *
 48  * If you want to use the refcount field, it must be used in such a way
 49  * that other CPUs temporarily incrementing and then decrementing the
 50  * refcount does not cause problems.  On receiving the page from
 51  * alloc_pages(), the refcount will be positive.
 52  *
 53  * If you allocate pages of order > 0, you can use some of the fields
 54  * in each subpage, but you may need to restore some of their values
 55  * afterwards.
 56  *
 57  * SLUB uses cmpxchg_double() to atomically update its freelist and
 58  * counters.  That requires that freelist & counters be adjacent and
 59  * double-word aligned.  We align all struct pages to double-word
 60  * boundaries, and ensure that 'freelist' is aligned within the
 61  * struct.
 62  */
 63 #ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
 64 #define _struct_page_alignment  __aligned(2 * sizeof(unsigned long))
 65 #else
 66 #define _struct_page_alignment
 67 #endif
 68 
 69 struct page {
 70         unsigned long flags;            /* Atomic flags, some possibly
 71                                          * updated asynchronously */
 72         /*
 73          * Five words (20/40 bytes) are available in this union.
 74          * WARNING: bit 0 of the first word is used for PageTail(). That
 75          * means the other users of this union MUST NOT use the bit to
 76          * avoid collision and false-positive PageTail().
 77          */
 78         union {
 79                 struct {        /* Page cache and anonymous pages */
 80                         /**
 81                          * @lru: Pageout list, eg. active_list protected by
 82                          * pgdat->lru_lock.  Sometimes used as a generic list
 83                          * by the page owner.
 84                          */
 85                         struct list_head lru;
 86                         /* See page-flags.h for PAGE_MAPPING_FLAGS */
 87                         struct address_space *mapping;
 88                         pgoff_t index;          /* Our offset within mapping. */
 89                         /**
 90                          * @private: Mapping-private opaque data.
 91                          * Usually used for buffer_heads if PagePrivate.
 92                          * Used for swp_entry_t if PageSwapCache.
 93                          * Indicates order in the buddy system if PageBuddy.
 94                          */
 95                         unsigned long private;
 96                 };
 97                 struct {        /* page_pool used by netstack */
 98                         /**
 99                          * @dma_addr: might require a 64-bit value even on
100                          * 32-bit architectures.
101                          */
102                         dma_addr_t dma_addr;
103                 };
104                 struct {        /* slab, slob and slub */
105                         union {
106                                 struct list_head slab_list;     /* uses lru */
107                                 struct {        /* Partial pages */
108                                         struct page *next;
109 #ifdef CONFIG_64BIT
110                                         int pages;      /* Nr of pages left */
111                                         int pobjects;   /* Approximate count */
112 #else
113                                         short int pages;
114                                         short int pobjects;
115 #endif
116                                 };
117                         };
118                         struct kmem_cache *slab_cache; /* not slob */
119                         /* Double-word boundary */
120                         void *freelist;         /* first free object */
121                         union {
122                                 void *s_mem;    /* slab: first object */
123                                 unsigned long counters;         /* SLUB */
124                                 struct {                        /* SLUB */
125                                         unsigned inuse:16;
126                                         unsigned objects:15;
127                                         unsigned frozen:1;
128                                 };
129                         };
130                 };
131                 struct {        /* Tail pages of compound page */
132                         unsigned long compound_head;    /* Bit zero is set */
133 
134                         /* First tail page only */
135                         unsigned char compound_dtor;
136                         unsigned char compound_order;
137                         atomic_t compound_mapcount;
138                 };
139                 struct {        /* Second tail page of compound page */
140                         unsigned long _compound_pad_1;  /* compound_head */
141                         unsigned long _compound_pad_2;
142                         struct list_head deferred_list;
143                 };
144                 struct {        /* Page table pages */
145                         unsigned long _pt_pad_1;        /* compound_head */
146                         pgtable_t pmd_huge_pte; /* protected by page->ptl */
147                         unsigned long _pt_pad_2;        /* mapping */
148                         union {
149                                 struct mm_struct *pt_mm; /* x86 pgds only */
150                                 atomic_t pt_frag_refcount; /* powerpc */
151                         };
152 #if ALLOC_SPLIT_PTLOCKS
153                         spinlock_t *ptl;
154 #else
155                         spinlock_t ptl;
156 #endif
157                 };
158                 struct {        /* ZONE_DEVICE pages */
159                         /** @pgmap: Points to the hosting device page map. */
160                         struct dev_pagemap *pgmap;
161                         unsigned long hmm_data;
162                         unsigned long _zd_pad_1;        /* uses mapping */
163                 };
164 
165                 /** @rcu_head: You can use this to free a page by RCU. */
166                 struct rcu_head rcu_head;
167         };
168 
169         union {         /* This union is 4 bytes in size. */
170                 /*
171                  * If the page can be mapped to userspace, encodes the number
172                  * of times this page is referenced by a page table.
173                  */
174                 atomic_t _mapcount;
175 
176                 /*
177                  * If the page is neither PageSlab nor mappable to userspace,
178                  * the value stored here may help determine what this page
179                  * is used for.  See page-flags.h for a list of page types
180                  * which are currently stored here.
181                  */
182                 unsigned int page_type;
183 
184                 unsigned int active;            /* SLAB */
185                 int units;                      /* SLOB */
186         };
187 
188         /* Usage count. *DO NOT USE DIRECTLY*. See page_ref.h */
189         atomic_t _refcount;
190 
191 #ifdef CONFIG_MEMCG
192         struct mem_cgroup *mem_cgroup;
193 #endif
194 
195         /*
196          * On machines where all RAM is mapped into kernel address space,
197          * we can simply calculate the virtual address. On machines with
198          * highmem some memory is mapped into kernel virtual memory
199          * dynamically, so we need a place to store that address.
200          * Note that this field could be 16 bits on x86 ... ;)
201          *
202          * Architectures with slow multiplication can define
203          * WANT_PAGE_VIRTUAL in asm/page.h
204          */
205 #if defined(WANT_PAGE_VIRTUAL)
206         void *virtual;                  /* Kernel virtual address (NULL if
207                                            not kmapped, ie. highmem) */
208 #endif /* WANT_PAGE_VIRTUAL */
209 
210 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
211         int _last_cpupid;
212 #endif
213 } _struct_page_alignment;
214 
215 /*
216  * Used for sizing the vmemmap region on some architectures
217  */
218 #define STRUCT_PAGE_MAX_SHIFT   (order_base_2(sizeof(struct page)))
219 
220 #define PAGE_FRAG_CACHE_MAX_SIZE        __ALIGN_MASK(32768, ~PAGE_MASK)
221 #define PAGE_FRAG_CACHE_MAX_ORDER       get_order(PAGE_FRAG_CACHE_MAX_SIZE)
222 
223 struct page_frag_cache {
224         void * va;
225 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
226         __u16 offset;
227         __u16 size;
228 #else
229         __u32 offset;
230 #endif
231         /* we maintain a pagecount bias, so that we dont dirty cache line
232          * containing page->_refcount every time we allocate a fragment.
233          */
234         unsigned int            pagecnt_bias;
235         bool pfmemalloc;
236 };
237 
238 typedef unsigned long vm_flags_t;
239 
240 /*
241  * A region containing a mapping of a non-memory backed file under NOMMU
242  * conditions.  These are held in a global tree and are pinned by the VMAs that
243  * map parts of them.
244  */
245 struct vm_region {
246         struct rb_node  vm_rb;          /* link in global region tree */
247         vm_flags_t      vm_flags;       /* VMA vm_flags */
248         unsigned long   vm_start;       /* start address of region */
249         unsigned long   vm_end;         /* region initialised to here */
250         unsigned long   vm_top;         /* region allocated to here */
251         unsigned long   vm_pgoff;       /* the offset in vm_file corresponding to vm_start */
252         struct file     *vm_file;       /* the backing file or NULL */
253 
254         int             vm_usage;       /* region usage count (access under nommu_region_sem) */
255         bool            vm_icache_flushed : 1; /* true if the icache has been flushed for
256                                                 * this region */
257 };
258 
259 #ifdef CONFIG_USERFAULTFD
260 #define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) { NULL, })
261 struct vm_userfaultfd_ctx {
262         struct userfaultfd_ctx *ctx;
263 };
264 #else /* CONFIG_USERFAULTFD */
265 #define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) {})
266 struct vm_userfaultfd_ctx {};
267 #endif /* CONFIG_USERFAULTFD */
268 
269 /*
270  * This struct defines a memory VMM memory area. There is one of these
271  * per VM-area/task.  A VM area is any part of the process virtual memory
272  * space that has a special rule for the page-fault handlers (ie a shared
273  * library, the executable area etc).
274  */
275 struct vm_area_struct {
276         /* The first cache line has the info for VMA tree walking. */
277 
278         unsigned long vm_start;         /* Our start address within vm_mm. */
279         unsigned long vm_end;           /* The first byte after our end address
280                                            within vm_mm. */
281 
282         /* linked list of VM areas per task, sorted by address */
283         struct vm_area_struct *vm_next, *vm_prev;
284 
285         struct rb_node vm_rb;
286 
287         /*
288          * Largest free memory gap in bytes to the left of this VMA.
289          * Either between this VMA and vma->vm_prev, or between one of the
290          * VMAs below us in the VMA rbtree and its ->vm_prev. This helps
291          * get_unmapped_area find a free area of the right size.
292          */
293         unsigned long rb_subtree_gap;
294 
295         /* Second cache line starts here. */
296 
297         struct mm_struct *vm_mm;        /* The address space we belong to. */
298         pgprot_t vm_page_prot;          /* Access permissions of this VMA. */
299         unsigned long vm_flags;         /* Flags, see mm.h. */
300 
301         /*
302          * For areas with an address space and backing store,
303          * linkage into the address_space->i_mmap interval tree.
304          */
305         struct {
306                 struct rb_node rb;
307                 unsigned long rb_subtree_last;
308         } shared;
309 
310         /*
311          * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma
312          * list, after a COW of one of the file pages.  A MAP_SHARED vma
313          * can only be in the i_mmap tree.  An anonymous MAP_PRIVATE, stack
314          * or brk vma (with NULL file) can only be in an anon_vma list.
315          */
316         struct list_head anon_vma_chain; /* Serialized by mmap_sem &
317                                           * page_table_lock */
318         struct anon_vma *anon_vma;      /* Serialized by page_table_lock */
319 
320         /* Function pointers to deal with this struct. */
321         const struct vm_operations_struct *vm_ops;
322 
323         /* Information about our backing store: */
324         unsigned long vm_pgoff;         /* Offset (within vm_file) in PAGE_SIZE
325                                            units */
326         struct file * vm_file;          /* File we map to (can be NULL). */
327         void * vm_private_data;         /* was vm_pte (shared mem) */
328 
329         atomic_long_t swap_readahead_info;
330 #ifndef CONFIG_MMU
331         struct vm_region *vm_region;    /* NOMMU mapping region */
332 #endif
333 #ifdef CONFIG_NUMA
334         struct mempolicy *vm_policy;    /* NUMA policy for the VMA */
335 #endif
336         struct vm_userfaultfd_ctx vm_userfaultfd_ctx;
337 } __randomize_layout;
338 
339 struct core_thread {
340         struct task_struct *task;
341         struct core_thread *next;
342 };
343 
344 struct core_state {
345         atomic_t nr_threads;
346         struct core_thread dumper;
347         struct completion startup;
348 };
349 
350 struct kioctx_table;
351 struct mm_struct {
352         struct {
353                 struct vm_area_struct *mmap;            /* list of VMAs */
354                 struct rb_root mm_rb;
355                 u64 vmacache_seqnum;                   /* per-thread vmacache */
356 #ifdef CONFIG_MMU
357                 unsigned long (*get_unmapped_area) (struct file *filp,
358                                 unsigned long addr, unsigned long len,
359                                 unsigned long pgoff, unsigned long flags);
360 #endif
361                 unsigned long mmap_base;        /* base of mmap area */
362                 unsigned long mmap_legacy_base; /* base of mmap area in bottom-up allocations */
363 #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
364                 /* Base adresses for compatible mmap() */
365                 unsigned long mmap_compat_base;
366                 unsigned long mmap_compat_legacy_base;
367 #endif
368                 unsigned long task_size;        /* size of task vm space */
369                 unsigned long highest_vm_end;   /* highest vma end address */
370                 pgd_t * pgd;
371 
372                 /**
373                  * @mm_users: The number of users including userspace.
374                  *
375                  * Use mmget()/mmget_not_zero()/mmput() to modify. When this
376                  * drops to 0 (i.e. when the task exits and there are no other
377                  * temporary reference holders), we also release a reference on
378                  * @mm_count (which may then free the &struct mm_struct if
379                  * @mm_count also drops to 0).
380                  */
381                 atomic_t mm_users;
382 
383                 /**
384                  * @mm_count: The number of references to &struct mm_struct
385                  * (@mm_users count as 1).
386                  *
387                  * Use mmgrab()/mmdrop() to modify. When this drops to 0, the
388                  * &struct mm_struct is freed.
389                  */
390                 atomic_t mm_count;
391 
392 #ifdef CONFIG_MMU
393                 atomic_long_t pgtables_bytes;   /* PTE page table pages */
394 #endif
395                 int map_count;                  /* number of VMAs */
396 
397                 spinlock_t page_table_lock; /* Protects page tables and some
398                                              * counters
399                                              */
400                 struct rw_semaphore mmap_sem;
401 
402                 struct list_head mmlist; /* List of maybe swapped mm's. These
403                                           * are globally strung together off
404                                           * init_mm.mmlist, and are protected
405                                           * by mmlist_lock
406                                           */
407 
408 
409                 unsigned long hiwater_rss; /* High-watermark of RSS usage */
410                 unsigned long hiwater_vm;  /* High-water virtual memory usage */
411 
412                 unsigned long total_vm;    /* Total pages mapped */
413                 unsigned long locked_vm;   /* Pages that have PG_mlocked set */
414                 atomic64_t    pinned_vm;   /* Refcount permanently increased */
415                 unsigned long data_vm;     /* VM_WRITE & ~VM_SHARED & ~VM_STACK */
416                 unsigned long exec_vm;     /* VM_EXEC & ~VM_WRITE & ~VM_STACK */
417                 unsigned long stack_vm;    /* VM_STACK */
418                 unsigned long def_flags;
419 
420                 spinlock_t arg_lock; /* protect the below fields */
421                 unsigned long start_code, end_code, start_data, end_data;
422                 unsigned long start_brk, brk, start_stack;
423                 unsigned long arg_start, arg_end, env_start, env_end;
424 
425                 unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
426 
427                 /*
428                  * Special counters, in some configurations protected by the
429                  * page_table_lock, in other configurations by being atomic.
430                  */
431                 struct mm_rss_stat rss_stat;
432 
433                 struct linux_binfmt *binfmt;
434 
435                 /* Architecture-specific MM context */
436                 mm_context_t context;
437 
438                 unsigned long flags; /* Must use atomic bitops to access */
439 
440                 struct core_state *core_state; /* coredumping support */
441 #ifdef CONFIG_MEMBARRIER
442                 atomic_t membarrier_state;
443 #endif
444 #ifdef CONFIG_AIO
445                 spinlock_t                      ioctx_lock;
446                 struct kioctx_table __rcu       *ioctx_table;
447 #endif
448 #ifdef CONFIG_MEMCG
449                 /*
450                  * "owner" points to a task that is regarded as the canonical
451                  * user/owner of this mm. All of the following must be true in
452                  * order for it to be changed:
453                  *
454                  * current == mm->owner
455                  * current->mm != mm
456                  * new_owner->mm == mm
457                  * new_owner->alloc_lock is held
458                  */
459                 struct task_struct __rcu *owner;
460 #endif
461                 struct user_namespace *user_ns;
462 
463                 /* store ref to file /proc/<pid>/exe symlink points to */
464                 struct file __rcu *exe_file;
465 #ifdef CONFIG_MMU_NOTIFIER
466                 struct mmu_notifier_mm *mmu_notifier_mm;
467 #endif
468 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
469                 pgtable_t pmd_huge_pte; /* protected by page_table_lock */
470 #endif
471 #ifdef CONFIG_NUMA_BALANCING
472                 /*
473                  * numa_next_scan is the next time that the PTEs will be marked
474                  * pte_numa. NUMA hinting faults will gather statistics and
475                  * migrate pages to new nodes if necessary.
476                  */
477                 unsigned long numa_next_scan;
478 
479                 /* Restart point for scanning and setting pte_numa */
480                 unsigned long numa_scan_offset;
481 
482                 /* numa_scan_seq prevents two threads setting pte_numa */
483                 int numa_scan_seq;
484 #endif
485                 /*
486                  * An operation with batched TLB flushing is going on. Anything
487                  * that can move process memory needs to flush the TLB when
488                  * moving a PROT_NONE or PROT_NUMA mapped page.
489                  */
490                 atomic_t tlb_flush_pending;
491 #ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
492                 /* See flush_tlb_batched_pending() */
493                 bool tlb_flush_batched;
494 #endif
495                 struct uprobes_state uprobes_state;
496 #ifdef CONFIG_HUGETLB_PAGE
497                 atomic_long_t hugetlb_usage;
498 #endif
499                 struct work_struct async_put_work;
500 
501 #if IS_ENABLED(CONFIG_HMM)
502                 /* HMM needs to track a few things per mm */
503                 struct hmm *hmm;
504 #endif
505         } __randomize_layout;
506 
507         /*
508          * The mm_cpumask needs to be at the end of mm_struct, because it
509          * is dynamically sized based on nr_cpu_ids.
510          */
511         unsigned long cpu_bitmap[];
512 };
513 
514 extern struct mm_struct init_mm;
515 
516 /* Pointer magic because the dynamic array size confuses some compilers. */
517 static inline void mm_init_cpumask(struct mm_struct *mm)
518 {
519         unsigned long cpu_bitmap = (unsigned long)mm;
520 
521         cpu_bitmap += offsetof(struct mm_struct, cpu_bitmap);
522         cpumask_clear((struct cpumask *)cpu_bitmap);
523 }
524 
525 /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
526 static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
527 {
528         return (struct cpumask *)&mm->cpu_bitmap;
529 }
530 
531 struct mmu_gather;
532 extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
533                                 unsigned long start, unsigned long end);
534 extern void tlb_finish_mmu(struct mmu_gather *tlb,
535                                 unsigned long start, unsigned long end);
536 
537 static inline void init_tlb_flush_pending(struct mm_struct *mm)
538 {
539         atomic_set(&mm->tlb_flush_pending, 0);
540 }
541 
542 static inline void inc_tlb_flush_pending(struct mm_struct *mm)
543 {
544         atomic_inc(&mm->tlb_flush_pending);
545         /*
546          * The only time this value is relevant is when there are indeed pages
547          * to flush. And we'll only flush pages after changing them, which
548          * requires the PTL.
549          *
550          * So the ordering here is:
551          *
552          *      atomic_inc(&mm->tlb_flush_pending);
553          *      spin_lock(&ptl);
554          *      ...
555          *      set_pte_at();
556          *      spin_unlock(&ptl);
557          *
558          *                              spin_lock(&ptl)
559          *                              mm_tlb_flush_pending();
560          *                              ....
561          *                              spin_unlock(&ptl);
562          *
563          *      flush_tlb_range();
564          *      atomic_dec(&mm->tlb_flush_pending);
565          *
566          * Where the increment if constrained by the PTL unlock, it thus
567          * ensures that the increment is visible if the PTE modification is
568          * visible. After all, if there is no PTE modification, nobody cares
569          * about TLB flushes either.
570          *
571          * This very much relies on users (mm_tlb_flush_pending() and
572          * mm_tlb_flush_nested()) only caring about _specific_ PTEs (and
573          * therefore specific PTLs), because with SPLIT_PTE_PTLOCKS and RCpc
574          * locks (PPC) the unlock of one doesn't order against the lock of
575          * another PTL.
576          *
577          * The decrement is ordered by the flush_tlb_range(), such that
578          * mm_tlb_flush_pending() will not return false unless all flushes have
579          * completed.
580          */
581 }
582 
583 static inline void dec_tlb_flush_pending(struct mm_struct *mm)
584 {
585         /*
586          * See inc_tlb_flush_pending().
587          *
588          * This cannot be smp_mb__before_atomic() because smp_mb() simply does
589          * not order against TLB invalidate completion, which is what we need.
590          *
591          * Therefore we must rely on tlb_flush_*() to guarantee order.
592          */
593         atomic_dec(&mm->tlb_flush_pending);
594 }
595 
596 static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
597 {
598         /*
599          * Must be called after having acquired the PTL; orders against that
600          * PTLs release and therefore ensures that if we observe the modified
601          * PTE we must also observe the increment from inc_tlb_flush_pending().
602          *
603          * That is, it only guarantees to return true if there is a flush
604          * pending for _this_ PTL.
605          */
606         return atomic_read(&mm->tlb_flush_pending);
607 }
608 
609 static inline bool mm_tlb_flush_nested(struct mm_struct *mm)
610 {
611         /*
612          * Similar to mm_tlb_flush_pending(), we must have acquired the PTL
613          * for which there is a TLB flush pending in order to guarantee
614          * we've seen both that PTE modification and the increment.
615          *
616          * (no requirement on actually still holding the PTL, that is irrelevant)
617          */
618         return atomic_read(&mm->tlb_flush_pending) > 1;
619 }
620 
621 struct vm_fault;
622 
623 /**
624  * typedef vm_fault_t - Return type for page fault handlers.
625  *
626  * Page fault handlers return a bitmask of %VM_FAULT values.
627  */
628 typedef __bitwise unsigned int vm_fault_t;
629 
630 /**
631  * enum vm_fault_reason - Page fault handlers return a bitmask of
632  * these values to tell the core VM what happened when handling the
633  * fault. Used to decide whether a process gets delivered SIGBUS or
634  * just gets major/minor fault counters bumped up.
635  *
636  * @VM_FAULT_OOM:               Out Of Memory
637  * @VM_FAULT_SIGBUS:            Bad access
638  * @VM_FAULT_MAJOR:             Page read from storage
639  * @VM_FAULT_WRITE:             Special case for get_user_pages
640  * @VM_FAULT_HWPOISON:          Hit poisoned small page
641  * @VM_FAULT_HWPOISON_LARGE:    Hit poisoned large page. Index encoded
642  *                              in upper bits
643  * @VM_FAULT_SIGSEGV:           segmentation fault
644  * @VM_FAULT_NOPAGE:            ->fault installed the pte, not return page
645  * @VM_FAULT_LOCKED:            ->fault locked the returned page
646  * @VM_FAULT_RETRY:             ->fault blocked, must retry
647  * @VM_FAULT_FALLBACK:          huge page fault failed, fall back to small
648  * @VM_FAULT_DONE_COW:          ->fault has fully handled COW
649  * @VM_FAULT_NEEDDSYNC:         ->fault did not modify page tables and needs
650  *                              fsync() to complete (for synchronous page faults
651  *                              in DAX)
652  * @VM_FAULT_HINDEX_MASK:       mask HINDEX value
653  *
654  */
655 enum vm_fault_reason {
656         VM_FAULT_OOM            = (__force vm_fault_t)0x000001,
657         VM_FAULT_SIGBUS         = (__force vm_fault_t)0x000002,
658         VM_FAULT_MAJOR          = (__force vm_fault_t)0x000004,
659         VM_FAULT_WRITE          = (__force vm_fault_t)0x000008,
660         VM_FAULT_HWPOISON       = (__force vm_fault_t)0x000010,
661         VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020,
662         VM_FAULT_SIGSEGV        = (__force vm_fault_t)0x000040,
663         VM_FAULT_NOPAGE         = (__force vm_fault_t)0x000100,
664         VM_FAULT_LOCKED         = (__force vm_fault_t)0x000200,
665         VM_FAULT_RETRY          = (__force vm_fault_t)0x000400,
666         VM_FAULT_FALLBACK       = (__force vm_fault_t)0x000800,
667         VM_FAULT_DONE_COW       = (__force vm_fault_t)0x001000,
668         VM_FAULT_NEEDDSYNC      = (__force vm_fault_t)0x002000,
669         VM_FAULT_HINDEX_MASK    = (__force vm_fault_t)0x0f0000,
670 };
671 
672 /* Encode hstate index for a hwpoisoned large page */
673 #define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16))
674 #define VM_FAULT_GET_HINDEX(x) (((__force unsigned int)(x) >> 16) & 0xf)
675 
676 #define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS |        \
677                         VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON |  \
678                         VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)
679 
680 #define VM_FAULT_RESULT_TRACE \
681         { VM_FAULT_OOM,                 "OOM" },        \
682         { VM_FAULT_SIGBUS,              "SIGBUS" },     \
683         { VM_FAULT_MAJOR,               "MAJOR" },      \
684         { VM_FAULT_WRITE,               "WRITE" },      \
685         { VM_FAULT_HWPOISON,            "HWPOISON" },   \
686         { VM_FAULT_HWPOISON_LARGE,      "HWPOISON_LARGE" },     \
687         { VM_FAULT_SIGSEGV,             "SIGSEGV" },    \
688         { VM_FAULT_NOPAGE,              "NOPAGE" },     \
689         { VM_FAULT_LOCKED,              "LOCKED" },     \
690         { VM_FAULT_RETRY,               "RETRY" },      \
691         { VM_FAULT_FALLBACK,            "FALLBACK" },   \
692         { VM_FAULT_DONE_COW,            "DONE_COW" },   \
693         { VM_FAULT_NEEDDSYNC,           "NEEDDSYNC" }
694 
695 struct vm_special_mapping {
696         const char *name;       /* The name, e.g. "[vdso]". */
697 
698         /*
699          * If .fault is not provided, this points to a
700          * NULL-terminated array of pages that back the special mapping.
701          *
702          * This must not be NULL unless .fault is provided.
703          */
704         struct page **pages;
705 
706         /*
707          * If non-NULL, then this is called to resolve page faults
708          * on the special mapping.  If used, .pages is not checked.
709          */
710         vm_fault_t (*fault)(const struct vm_special_mapping *sm,
711                                 struct vm_area_struct *vma,
712                                 struct vm_fault *vmf);
713 
714         int (*mremap)(const struct vm_special_mapping *sm,
715                      struct vm_area_struct *new_vma);
716 };
717 
718 enum tlb_flush_reason {
719         TLB_FLUSH_ON_TASK_SWITCH,
720         TLB_REMOTE_SHOOTDOWN,
721         TLB_LOCAL_SHOOTDOWN,
722         TLB_LOCAL_MM_SHOOTDOWN,
723         TLB_REMOTE_SEND_IPI,
724         NR_TLB_FLUSH_REASONS,
725 };
726 
727  /*
728   * A swap entry has to fit into a "unsigned long", as the entry is hidden
729   * in the "index" field of the swapper address space.
730   */
731 typedef struct {
732         unsigned long val;
733 } swp_entry_t;
734 
735 #endif /* _LINUX_MM_TYPES_H */
736 

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