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 typedef int vm_fault_t; 26 27 struct address_space; 28 struct mem_cgroup; 29 struct hmm; 30 31 /* 32 * Each physical page in the system has a struct page associated with 33 * it to keep track of whatever it is we are using the page for at the 34 * moment. Note that we have no way to track which tasks are using 35 * a page, though if it is a pagecache page, rmap structures can tell us 36 * who is mapping it. 37 * 38 * If you allocate the page using alloc_pages(), you can use some of the 39 * space in struct page for your own purposes. The five words in the main 40 * union are available, except for bit 0 of the first word which must be 41 * kept clear. Many users use this word to store a pointer to an object 42 * which is guaranteed to be aligned. If you use the same storage as 43 * page->mapping, you must restore it to NULL before freeing the page. 44 * 45 * If your page will not be mapped to userspace, you can also use the four 46 * bytes in the mapcount union, but you must call page_mapcount_reset() 47 * before freeing it. 48 * 49 * If you want to use the refcount field, it must be used in such a way 50 * that other CPUs temporarily incrementing and then decrementing the 51 * refcount does not cause problems. On receiving the page from 52 * alloc_pages(), the refcount will be positive. 53 * 54 * If you allocate pages of order > 0, you can use some of the fields 55 * in each subpage, but you may need to restore some of their values 56 * afterwards. 57 * 58 * SLUB uses cmpxchg_double() to atomically update its freelist and 59 * counters. That requires that freelist & counters be adjacent and 60 * double-word aligned. We align all struct pages to double-word 61 * boundaries, and ensure that 'freelist' is aligned within the 62 * struct. 63 */ 64 #ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE 65 #define _struct_page_alignment __aligned(2 * sizeof(unsigned long)) 66 #else 67 #define _struct_page_alignment 68 #endif 69 70 struct page { 71 unsigned long flags; /* Atomic flags, some possibly 72 * updated asynchronously */ 73 /* 74 * Five words (20/40 bytes) are available in this union. 75 * WARNING: bit 0 of the first word is used for PageTail(). That 76 * means the other users of this union MUST NOT use the bit to 77 * avoid collision and false-positive PageTail(). 78 */ 79 union { 80 struct { /* Page cache and anonymous pages */ 81 /** 82 * @lru: Pageout list, eg. active_list protected by 83 * zone_lru_lock. Sometimes used as a generic list 84 * by the page owner. 85 */ 86 struct list_head lru; 87 /* See page-flags.h for PAGE_MAPPING_FLAGS */ 88 struct address_space *mapping; 89 pgoff_t index; /* Our offset within mapping. */ 90 /** 91 * @private: Mapping-private opaque data. 92 * Usually used for buffer_heads if PagePrivate. 93 * Used for swp_entry_t if PageSwapCache. 94 * Indicates order in the buddy system if PageBuddy. 95 */ 96 unsigned long private; 97 }; 98 struct { /* slab, slob and slub */ 99 union { 100 struct list_head slab_list; /* uses lru */ 101 struct { /* Partial pages */ 102 struct page *next; 103 #ifdef CONFIG_64BIT 104 int pages; /* Nr of pages left */ 105 int pobjects; /* Approximate count */ 106 #else 107 short int pages; 108 short int pobjects; 109 #endif 110 }; 111 }; 112 struct kmem_cache *slab_cache; /* not slob */ 113 /* Double-word boundary */ 114 void *freelist; /* first free object */ 115 union { 116 void *s_mem; /* slab: first object */ 117 unsigned long counters; /* SLUB */ 118 struct { /* SLUB */ 119 unsigned inuse:16; 120 unsigned objects:15; 121 unsigned frozen:1; 122 }; 123 }; 124 }; 125 struct { /* Tail pages of compound page */ 126 unsigned long compound_head; /* Bit zero is set */ 127 128 /* First tail page only */ 129 unsigned char compound_dtor; 130 unsigned char compound_order; 131 atomic_t compound_mapcount; 132 }; 133 struct { /* Second tail page of compound page */ 134 unsigned long _compound_pad_1; /* compound_head */ 135 unsigned long _compound_pad_2; 136 struct list_head deferred_list; 137 }; 138 struct { /* Page table pages */ 139 unsigned long _pt_pad_1; /* compound_head */ 140 pgtable_t pmd_huge_pte; /* protected by page->ptl */ 141 unsigned long _pt_pad_2; /* mapping */ 142 struct mm_struct *pt_mm; /* x86 pgds only */ 143 #if ALLOC_SPLIT_PTLOCKS 144 spinlock_t *ptl; 145 #else 146 spinlock_t ptl; 147 #endif 148 }; 149 struct { /* ZONE_DEVICE pages */ 150 /** @pgmap: Points to the hosting device page map. */ 151 struct dev_pagemap *pgmap; 152 unsigned long hmm_data; 153 unsigned long _zd_pad_1; /* uses mapping */ 154 }; 155 156 /** @rcu_head: You can use this to free a page by RCU. */ 157 struct rcu_head rcu_head; 158 }; 159 160 union { /* This union is 4 bytes in size. */ 161 /* 162 * If the page can be mapped to userspace, encodes the number 163 * of times this page is referenced by a page table. 164 */ 165 atomic_t _mapcount; 166 167 /* 168 * If the page is neither PageSlab nor mappable to userspace, 169 * the value stored here may help determine what this page 170 * is used for. See page-flags.h for a list of page types 171 * which are currently stored here. 172 */ 173 unsigned int page_type; 174 175 unsigned int active; /* SLAB */ 176 int units; /* SLOB */ 177 }; 178 179 /* Usage count. *DO NOT USE DIRECTLY*. See page_ref.h */ 180 atomic_t _refcount; 181 182 #ifdef CONFIG_MEMCG 183 struct mem_cgroup *mem_cgroup; 184 #endif 185 186 /* 187 * On machines where all RAM is mapped into kernel address space, 188 * we can simply calculate the virtual address. On machines with 189 * highmem some memory is mapped into kernel virtual memory 190 * dynamically, so we need a place to store that address. 191 * Note that this field could be 16 bits on x86 ... ;) 192 * 193 * Architectures with slow multiplication can define 194 * WANT_PAGE_VIRTUAL in asm/page.h 195 */ 196 #if defined(WANT_PAGE_VIRTUAL) 197 void *virtual; /* Kernel virtual address (NULL if 198 not kmapped, ie. highmem) */ 199 #endif /* WANT_PAGE_VIRTUAL */ 200 201 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS 202 int _last_cpupid; 203 #endif 204 } _struct_page_alignment; 205 206 #define PAGE_FRAG_CACHE_MAX_SIZE __ALIGN_MASK(32768, ~PAGE_MASK) 207 #define PAGE_FRAG_CACHE_MAX_ORDER get_order(PAGE_FRAG_CACHE_MAX_SIZE) 208 209 struct page_frag_cache { 210 void * va; 211 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) 212 __u16 offset; 213 __u16 size; 214 #else 215 __u32 offset; 216 #endif 217 /* we maintain a pagecount bias, so that we dont dirty cache line 218 * containing page->_refcount every time we allocate a fragment. 219 */ 220 unsigned int pagecnt_bias; 221 bool pfmemalloc; 222 }; 223 224 typedef unsigned long vm_flags_t; 225 226 /* 227 * A region containing a mapping of a non-memory backed file under NOMMU 228 * conditions. These are held in a global tree and are pinned by the VMAs that 229 * map parts of them. 230 */ 231 struct vm_region { 232 struct rb_node vm_rb; /* link in global region tree */ 233 vm_flags_t vm_flags; /* VMA vm_flags */ 234 unsigned long vm_start; /* start address of region */ 235 unsigned long vm_end; /* region initialised to here */ 236 unsigned long vm_top; /* region allocated to here */ 237 unsigned long vm_pgoff; /* the offset in vm_file corresponding to vm_start */ 238 struct file *vm_file; /* the backing file or NULL */ 239 240 int vm_usage; /* region usage count (access under nommu_region_sem) */ 241 bool vm_icache_flushed : 1; /* true if the icache has been flushed for 242 * this region */ 243 }; 244 245 #ifdef CONFIG_USERFAULTFD 246 #define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) { NULL, }) 247 struct vm_userfaultfd_ctx { 248 struct userfaultfd_ctx *ctx; 249 }; 250 #else /* CONFIG_USERFAULTFD */ 251 #define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) {}) 252 struct vm_userfaultfd_ctx {}; 253 #endif /* CONFIG_USERFAULTFD */ 254 255 /* 256 * This struct defines a memory VMM memory area. There is one of these 257 * per VM-area/task. A VM area is any part of the process virtual memory 258 * space that has a special rule for the page-fault handlers (ie a shared 259 * library, the executable area etc). 260 */ 261 struct vm_area_struct { 262 /* The first cache line has the info for VMA tree walking. */ 263 264 unsigned long vm_start; /* Our start address within vm_mm. */ 265 unsigned long vm_end; /* The first byte after our end address 266 within vm_mm. */ 267 268 /* linked list of VM areas per task, sorted by address */ 269 struct vm_area_struct *vm_next, *vm_prev; 270 271 struct rb_node vm_rb; 272 273 /* 274 * Largest free memory gap in bytes to the left of this VMA. 275 * Either between this VMA and vma->vm_prev, or between one of the 276 * VMAs below us in the VMA rbtree and its ->vm_prev. This helps 277 * get_unmapped_area find a free area of the right size. 278 */ 279 unsigned long rb_subtree_gap; 280 281 /* Second cache line starts here. */ 282 283 struct mm_struct *vm_mm; /* The address space we belong to. */ 284 pgprot_t vm_page_prot; /* Access permissions of this VMA. */ 285 unsigned long vm_flags; /* Flags, see mm.h. */ 286 287 /* 288 * For areas with an address space and backing store, 289 * linkage into the address_space->i_mmap interval tree. 290 */ 291 struct { 292 struct rb_node rb; 293 unsigned long rb_subtree_last; 294 } shared; 295 296 /* 297 * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma 298 * list, after a COW of one of the file pages. A MAP_SHARED vma 299 * can only be in the i_mmap tree. An anonymous MAP_PRIVATE, stack 300 * or brk vma (with NULL file) can only be in an anon_vma list. 301 */ 302 struct list_head anon_vma_chain; /* Serialized by mmap_sem & 303 * page_table_lock */ 304 struct anon_vma *anon_vma; /* Serialized by page_table_lock */ 305 306 /* Function pointers to deal with this struct. */ 307 const struct vm_operations_struct *vm_ops; 308 309 /* Information about our backing store: */ 310 unsigned long vm_pgoff; /* Offset (within vm_file) in PAGE_SIZE 311 units */ 312 struct file * vm_file; /* File we map to (can be NULL). */ 313 void * vm_private_data; /* was vm_pte (shared mem) */ 314 315 atomic_long_t swap_readahead_info; 316 #ifndef CONFIG_MMU 317 struct vm_region *vm_region; /* NOMMU mapping region */ 318 #endif 319 #ifdef CONFIG_NUMA 320 struct mempolicy *vm_policy; /* NUMA policy for the VMA */ 321 #endif 322 struct vm_userfaultfd_ctx vm_userfaultfd_ctx; 323 } __randomize_layout; 324 325 struct core_thread { 326 struct task_struct *task; 327 struct core_thread *next; 328 }; 329 330 struct core_state { 331 atomic_t nr_threads; 332 struct core_thread dumper; 333 struct completion startup; 334 }; 335 336 struct kioctx_table; 337 struct mm_struct { 338 struct vm_area_struct *mmap; /* list of VMAs */ 339 struct rb_root mm_rb; 340 u32 vmacache_seqnum; /* per-thread vmacache */ 341 #ifdef CONFIG_MMU 342 unsigned long (*get_unmapped_area) (struct file *filp, 343 unsigned long addr, unsigned long len, 344 unsigned long pgoff, unsigned long flags); 345 #endif 346 unsigned long mmap_base; /* base of mmap area */ 347 unsigned long mmap_legacy_base; /* base of mmap area in bottom-up allocations */ 348 #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES 349 /* Base adresses for compatible mmap() */ 350 unsigned long mmap_compat_base; 351 unsigned long mmap_compat_legacy_base; 352 #endif 353 unsigned long task_size; /* size of task vm space */ 354 unsigned long highest_vm_end; /* highest vma end address */ 355 pgd_t * pgd; 356 357 /** 358 * @mm_users: The number of users including userspace. 359 * 360 * Use mmget()/mmget_not_zero()/mmput() to modify. When this drops 361 * to 0 (i.e. when the task exits and there are no other temporary 362 * reference holders), we also release a reference on @mm_count 363 * (which may then free the &struct mm_struct if @mm_count also 364 * drops to 0). 365 */ 366 atomic_t mm_users; 367 368 /** 369 * @mm_count: The number of references to &struct mm_struct 370 * (@mm_users count as 1). 371 * 372 * Use mmgrab()/mmdrop() to modify. When this drops to 0, the 373 * &struct mm_struct is freed. 374 */ 375 atomic_t mm_count; 376 377 #ifdef CONFIG_MMU 378 atomic_long_t pgtables_bytes; /* PTE page table pages */ 379 #endif 380 int map_count; /* number of VMAs */ 381 382 spinlock_t page_table_lock; /* Protects page tables and some counters */ 383 struct rw_semaphore mmap_sem; 384 385 struct list_head mmlist; /* List of maybe swapped mm's. These are globally strung 386 * together off init_mm.mmlist, and are protected 387 * by mmlist_lock 388 */ 389 390 391 unsigned long hiwater_rss; /* High-watermark of RSS usage */ 392 unsigned long hiwater_vm; /* High-water virtual memory usage */ 393 394 unsigned long total_vm; /* Total pages mapped */ 395 unsigned long locked_vm; /* Pages that have PG_mlocked set */ 396 unsigned long pinned_vm; /* Refcount permanently increased */ 397 unsigned long data_vm; /* VM_WRITE & ~VM_SHARED & ~VM_STACK */ 398 unsigned long exec_vm; /* VM_EXEC & ~VM_WRITE & ~VM_STACK */ 399 unsigned long stack_vm; /* VM_STACK */ 400 unsigned long def_flags; 401 402 spinlock_t arg_lock; /* protect the below fields */ 403 unsigned long start_code, end_code, start_data, end_data; 404 unsigned long start_brk, brk, start_stack; 405 unsigned long arg_start, arg_end, env_start, env_end; 406 407 unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */ 408 409 /* 410 * Special counters, in some configurations protected by the 411 * page_table_lock, in other configurations by being atomic. 412 */ 413 struct mm_rss_stat rss_stat; 414 415 struct linux_binfmt *binfmt; 416 417 cpumask_var_t cpu_vm_mask_var; 418 419 /* Architecture-specific MM context */ 420 mm_context_t context; 421 422 unsigned long flags; /* Must use atomic bitops to access the bits */ 423 424 struct core_state *core_state; /* coredumping support */ 425 #ifdef CONFIG_MEMBARRIER 426 atomic_t membarrier_state; 427 #endif 428 #ifdef CONFIG_AIO 429 spinlock_t ioctx_lock; 430 struct kioctx_table __rcu *ioctx_table; 431 #endif 432 #ifdef CONFIG_MEMCG 433 /* 434 * "owner" points to a task that is regarded as the canonical 435 * user/owner of this mm. All of the following must be true in 436 * order for it to be changed: 437 * 438 * current == mm->owner 439 * current->mm != mm 440 * new_owner->mm == mm 441 * new_owner->alloc_lock is held 442 */ 443 struct task_struct __rcu *owner; 444 #endif 445 struct user_namespace *user_ns; 446 447 /* store ref to file /proc/<pid>/exe symlink points to */ 448 struct file __rcu *exe_file; 449 #ifdef CONFIG_MMU_NOTIFIER 450 struct mmu_notifier_mm *mmu_notifier_mm; 451 #endif 452 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS 453 pgtable_t pmd_huge_pte; /* protected by page_table_lock */ 454 #endif 455 #ifdef CONFIG_CPUMASK_OFFSTACK 456 struct cpumask cpumask_allocation; 457 #endif 458 #ifdef CONFIG_NUMA_BALANCING 459 /* 460 * numa_next_scan is the next time that the PTEs will be marked 461 * pte_numa. NUMA hinting faults will gather statistics and migrate 462 * pages to new nodes if necessary. 463 */ 464 unsigned long numa_next_scan; 465 466 /* Restart point for scanning and setting pte_numa */ 467 unsigned long numa_scan_offset; 468 469 /* numa_scan_seq prevents two threads setting pte_numa */ 470 int numa_scan_seq; 471 #endif 472 /* 473 * An operation with batched TLB flushing is going on. Anything that 474 * can move process memory needs to flush the TLB when moving a 475 * PROT_NONE or PROT_NUMA mapped page. 476 */ 477 atomic_t tlb_flush_pending; 478 #ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH 479 /* See flush_tlb_batched_pending() */ 480 bool tlb_flush_batched; 481 #endif 482 struct uprobes_state uprobes_state; 483 #ifdef CONFIG_HUGETLB_PAGE 484 atomic_long_t hugetlb_usage; 485 #endif 486 struct work_struct async_put_work; 487 488 #if IS_ENABLED(CONFIG_HMM) 489 /* HMM needs to track a few things per mm */ 490 struct hmm *hmm; 491 #endif 492 } __randomize_layout; 493 494 extern struct mm_struct init_mm; 495 496 static inline void mm_init_cpumask(struct mm_struct *mm) 497 { 498 #ifdef CONFIG_CPUMASK_OFFSTACK 499 mm->cpu_vm_mask_var = &mm->cpumask_allocation; 500 #endif 501 cpumask_clear(mm->cpu_vm_mask_var); 502 } 503 504 /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */ 505 static inline cpumask_t *mm_cpumask(struct mm_struct *mm) 506 { 507 return mm->cpu_vm_mask_var; 508 } 509 510 struct mmu_gather; 511 extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, 512 unsigned long start, unsigned long end); 513 extern void tlb_finish_mmu(struct mmu_gather *tlb, 514 unsigned long start, unsigned long end); 515 516 static inline void init_tlb_flush_pending(struct mm_struct *mm) 517 { 518 atomic_set(&mm->tlb_flush_pending, 0); 519 } 520 521 static inline void inc_tlb_flush_pending(struct mm_struct *mm) 522 { 523 atomic_inc(&mm->tlb_flush_pending); 524 /* 525 * The only time this value is relevant is when there are indeed pages 526 * to flush. And we'll only flush pages after changing them, which 527 * requires the PTL. 528 * 529 * So the ordering here is: 530 * 531 * atomic_inc(&mm->tlb_flush_pending); 532 * spin_lock(&ptl); 533 * ... 534 * set_pte_at(); 535 * spin_unlock(&ptl); 536 * 537 * spin_lock(&ptl) 538 * mm_tlb_flush_pending(); 539 * .... 540 * spin_unlock(&ptl); 541 * 542 * flush_tlb_range(); 543 * atomic_dec(&mm->tlb_flush_pending); 544 * 545 * Where the increment if constrained by the PTL unlock, it thus 546 * ensures that the increment is visible if the PTE modification is 547 * visible. After all, if there is no PTE modification, nobody cares 548 * about TLB flushes either. 549 * 550 * This very much relies on users (mm_tlb_flush_pending() and 551 * mm_tlb_flush_nested()) only caring about _specific_ PTEs (and 552 * therefore specific PTLs), because with SPLIT_PTE_PTLOCKS and RCpc 553 * locks (PPC) the unlock of one doesn't order against the lock of 554 * another PTL. 555 * 556 * The decrement is ordered by the flush_tlb_range(), such that 557 * mm_tlb_flush_pending() will not return false unless all flushes have 558 * completed. 559 */ 560 } 561 562 static inline void dec_tlb_flush_pending(struct mm_struct *mm) 563 { 564 /* 565 * See inc_tlb_flush_pending(). 566 * 567 * This cannot be smp_mb__before_atomic() because smp_mb() simply does 568 * not order against TLB invalidate completion, which is what we need. 569 * 570 * Therefore we must rely on tlb_flush_*() to guarantee order. 571 */ 572 atomic_dec(&mm->tlb_flush_pending); 573 } 574 575 static inline bool mm_tlb_flush_pending(struct mm_struct *mm) 576 { 577 /* 578 * Must be called after having acquired the PTL; orders against that 579 * PTLs release and therefore ensures that if we observe the modified 580 * PTE we must also observe the increment from inc_tlb_flush_pending(). 581 * 582 * That is, it only guarantees to return true if there is a flush 583 * pending for _this_ PTL. 584 */ 585 return atomic_read(&mm->tlb_flush_pending); 586 } 587 588 static inline bool mm_tlb_flush_nested(struct mm_struct *mm) 589 { 590 /* 591 * Similar to mm_tlb_flush_pending(), we must have acquired the PTL 592 * for which there is a TLB flush pending in order to guarantee 593 * we've seen both that PTE modification and the increment. 594 * 595 * (no requirement on actually still holding the PTL, that is irrelevant) 596 */ 597 return atomic_read(&mm->tlb_flush_pending) > 1; 598 } 599 600 struct vm_fault; 601 602 struct vm_special_mapping { 603 const char *name; /* The name, e.g. "[vdso]". */ 604 605 /* 606 * If .fault is not provided, this points to a 607 * NULL-terminated array of pages that back the special mapping. 608 * 609 * This must not be NULL unless .fault is provided. 610 */ 611 struct page **pages; 612 613 /* 614 * If non-NULL, then this is called to resolve page faults 615 * on the special mapping. If used, .pages is not checked. 616 */ 617 vm_fault_t (*fault)(const struct vm_special_mapping *sm, 618 struct vm_area_struct *vma, 619 struct vm_fault *vmf); 620 621 int (*mremap)(const struct vm_special_mapping *sm, 622 struct vm_area_struct *new_vma); 623 }; 624 625 enum tlb_flush_reason { 626 TLB_FLUSH_ON_TASK_SWITCH, 627 TLB_REMOTE_SHOOTDOWN, 628 TLB_LOCAL_SHOOTDOWN, 629 TLB_LOCAL_MM_SHOOTDOWN, 630 TLB_REMOTE_SEND_IPI, 631 NR_TLB_FLUSH_REASONS, 632 }; 633 634 /* 635 * A swap entry has to fit into a "unsigned long", as the entry is hidden 636 * in the "index" field of the swapper address space. 637 */ 638 typedef struct { 639 unsigned long val; 640 } swp_entry_t; 641 642 #endif /* _LINUX_MM_TYPES_H */ 643