Latest Bootlin talks

at Live Embedded Event

Latest Bootlin videos and slides

given at the
Live Embedded Event
conference

Bootlin logo

Elixir Cross Referencer

  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
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_HUGE_MM_H
#define _LINUX_HUGE_MM_H

#include <linux/sched/coredump.h>
#include <linux/mm_types.h>

#include <linux/fs.h> /* only for vma_is_dax() */

extern vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf);
extern int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
			 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
			 struct vm_area_struct *vma);
extern void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd);
extern int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
			 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
			 struct vm_area_struct *vma);

#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
extern void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud);
#else
static inline void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
{
}
#endif

extern vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd);
extern struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
					  unsigned long addr,
					  pmd_t *pmd,
					  unsigned int flags);
extern bool madvise_free_huge_pmd(struct mmu_gather *tlb,
			struct vm_area_struct *vma,
			pmd_t *pmd, unsigned long addr, unsigned long next);
extern int zap_huge_pmd(struct mmu_gather *tlb,
			struct vm_area_struct *vma,
			pmd_t *pmd, unsigned long addr);
extern int zap_huge_pud(struct mmu_gather *tlb,
			struct vm_area_struct *vma,
			pud_t *pud, unsigned long addr);
extern bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
			 unsigned long new_addr,
			 pmd_t *old_pmd, pmd_t *new_pmd);
extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
			unsigned long addr, pgprot_t newprot,
			unsigned long cp_flags);
vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
				   pgprot_t pgprot, bool write);

/**
 * vmf_insert_pfn_pmd - insert a pmd size pfn
 * @vmf: Structure describing the fault
 * @pfn: pfn to insert
 * @pgprot: page protection to use
 * @write: whether it's a write fault
 *
 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info.
 *
 * Return: vm_fault_t value.
 */
static inline vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn,
					    bool write)
{
	return vmf_insert_pfn_pmd_prot(vmf, pfn, vmf->vma->vm_page_prot, write);
}
vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn,
				   pgprot_t pgprot, bool write);

/**
 * vmf_insert_pfn_pud - insert a pud size pfn
 * @vmf: Structure describing the fault
 * @pfn: pfn to insert
 * @pgprot: page protection to use
 * @write: whether it's a write fault
 *
 * Insert a pud size pfn. See vmf_insert_pfn() for additional info.
 *
 * Return: vm_fault_t value.
 */
static inline vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn,
					    bool write)
{
	return vmf_insert_pfn_pud_prot(vmf, pfn, vmf->vma->vm_page_prot, write);
}

enum transparent_hugepage_flag {
	TRANSPARENT_HUGEPAGE_FLAG,
	TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
	TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
	TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
	TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
	TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
	TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG,
	TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG,
#ifdef CONFIG_DEBUG_VM
	TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG,
#endif
};

struct kobject;
struct kobj_attribute;

extern ssize_t single_hugepage_flag_store(struct kobject *kobj,
				 struct kobj_attribute *attr,
				 const char *buf, size_t count,
				 enum transparent_hugepage_flag flag);
extern ssize_t single_hugepage_flag_show(struct kobject *kobj,
				struct kobj_attribute *attr, char *buf,
				enum transparent_hugepage_flag flag);
extern struct kobj_attribute shmem_enabled_attr;

#define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
#define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define HPAGE_PMD_SHIFT PMD_SHIFT
#define HPAGE_PMD_SIZE	((1UL) << HPAGE_PMD_SHIFT)
#define HPAGE_PMD_MASK	(~(HPAGE_PMD_SIZE - 1))

#define HPAGE_PUD_SHIFT PUD_SHIFT
#define HPAGE_PUD_SIZE	((1UL) << HPAGE_PUD_SHIFT)
#define HPAGE_PUD_MASK	(~(HPAGE_PUD_SIZE - 1))

extern unsigned long transparent_hugepage_flags;

/*
 * to be used on vmas which are known to support THP.
 * Use transparent_hugepage_enabled otherwise
 */
static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
{
	if (vma->vm_flags & VM_NOHUGEPAGE)
		return false;

	if (vma_is_temporary_stack(vma))
		return false;

	if (test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
		return false;

	if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_FLAG))
		return true;
	/*
	 * For dax vmas, try to always use hugepage mappings. If the kernel does
	 * not support hugepages, fsdax mappings will fallback to PAGE_SIZE
	 * mappings, and device-dax namespaces, that try to guarantee a given
	 * mapping size, will fail to enable
	 */
	if (vma_is_dax(vma))
		return true;

	if (transparent_hugepage_flags &
				(1 << TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG))
		return !!(vma->vm_flags & VM_HUGEPAGE);

	return false;
}

bool transparent_hugepage_enabled(struct vm_area_struct *vma);

#define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)

static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
		unsigned long haddr)
{
	/* Don't have to check pgoff for anonymous vma */
	if (!vma_is_anonymous(vma)) {
		if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
			(vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
			return false;
	}

	if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
		return false;
	return true;
}

#define transparent_hugepage_use_zero_page()				\
	(transparent_hugepage_flags &					\
	 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG))

extern unsigned long thp_get_unmapped_area(struct file *filp,
		unsigned long addr, unsigned long len, unsigned long pgoff,
		unsigned long flags);

extern void prep_transhuge_page(struct page *page);
extern void free_transhuge_page(struct page *page);
bool is_transparent_hugepage(struct page *page);

bool can_split_huge_page(struct page *page, int *pextra_pins);
int split_huge_page_to_list(struct page *page, struct list_head *list);
static inline int split_huge_page(struct page *page)
{
	return split_huge_page_to_list(page, NULL);
}
void deferred_split_huge_page(struct page *page);

void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
		unsigned long address, bool freeze, struct page *page);

#define split_huge_pmd(__vma, __pmd, __address)				\
	do {								\
		pmd_t *____pmd = (__pmd);				\
		if (is_swap_pmd(*____pmd) || pmd_trans_huge(*____pmd)	\
					|| pmd_devmap(*____pmd))	\
			__split_huge_pmd(__vma, __pmd, __address,	\
						false, NULL);		\
	}  while (0)


void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
		bool freeze, struct page *page);

void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
		unsigned long address);

#define split_huge_pud(__vma, __pud, __address)				\
	do {								\
		pud_t *____pud = (__pud);				\
		if (pud_trans_huge(*____pud)				\
					|| pud_devmap(*____pud))	\
			__split_huge_pud(__vma, __pud, __address);	\
	}  while (0)

extern int hugepage_madvise(struct vm_area_struct *vma,
			    unsigned long *vm_flags, int advice);
extern void vma_adjust_trans_huge(struct vm_area_struct *vma,
				    unsigned long start,
				    unsigned long end,
				    long adjust_next);
extern spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd,
		struct vm_area_struct *vma);
extern spinlock_t *__pud_trans_huge_lock(pud_t *pud,
		struct vm_area_struct *vma);

static inline int is_swap_pmd(pmd_t pmd)
{
	return !pmd_none(pmd) && !pmd_present(pmd);
}

/* mmap_lock must be held on entry */
static inline spinlock_t *pmd_trans_huge_lock(pmd_t *pmd,
		struct vm_area_struct *vma)
{
	if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd))
		return __pmd_trans_huge_lock(pmd, vma);
	else
		return NULL;
}
static inline spinlock_t *pud_trans_huge_lock(pud_t *pud,
		struct vm_area_struct *vma)
{
	if (pud_trans_huge(*pud) || pud_devmap(*pud))
		return __pud_trans_huge_lock(pud, vma);
	else
		return NULL;
}

/**
 * thp_head - Head page of a transparent huge page.
 * @page: Any page (tail, head or regular) found in the page cache.
 */
static inline struct page *thp_head(struct page *page)
{
	return compound_head(page);
}

/**
 * thp_order - Order of a transparent huge page.
 * @page: Head page of a transparent huge page.
 */
static inline unsigned int thp_order(struct page *page)
{
	VM_BUG_ON_PGFLAGS(PageTail(page), page);
	if (PageHead(page))
		return HPAGE_PMD_ORDER;
	return 0;
}

/**
 * thp_nr_pages - The number of regular pages in this huge page.
 * @page: The head page of a huge page.
 */
static inline int thp_nr_pages(struct page *page)
{
	VM_BUG_ON_PGFLAGS(PageTail(page), page);
	if (PageHead(page))
		return HPAGE_PMD_NR;
	return 1;
}

struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
		pmd_t *pmd, int flags, struct dev_pagemap **pgmap);
struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
		pud_t *pud, int flags, struct dev_pagemap **pgmap);

extern vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t orig_pmd);

extern struct page *huge_zero_page;

static inline bool is_huge_zero_page(struct page *page)
{
	return READ_ONCE(huge_zero_page) == page;
}

static inline bool is_huge_zero_pmd(pmd_t pmd)
{
	return is_huge_zero_page(pmd_page(pmd));
}

static inline bool is_huge_zero_pud(pud_t pud)
{
	return false;
}

struct page *mm_get_huge_zero_page(struct mm_struct *mm);
void mm_put_huge_zero_page(struct mm_struct *mm);

#define mk_huge_pmd(page, prot) pmd_mkhuge(mk_pmd(page, prot))

static inline bool thp_migration_supported(void)
{
	return IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION);
}

static inline struct list_head *page_deferred_list(struct page *page)
{
	/*
	 * Global or memcg deferred list in the second tail pages is
	 * occupied by compound_head.
	 */
	return &page[2].deferred_list;
}

#else /* CONFIG_TRANSPARENT_HUGEPAGE */
#define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
#define HPAGE_PMD_MASK ({ BUILD_BUG(); 0; })
#define HPAGE_PMD_SIZE ({ BUILD_BUG(); 0; })

#define HPAGE_PUD_SHIFT ({ BUILD_BUG(); 0; })
#define HPAGE_PUD_MASK ({ BUILD_BUG(); 0; })
#define HPAGE_PUD_SIZE ({ BUILD_BUG(); 0; })

static inline struct page *thp_head(struct page *page)
{
	VM_BUG_ON_PGFLAGS(PageTail(page), page);
	return page;
}

static inline unsigned int thp_order(struct page *page)
{
	VM_BUG_ON_PGFLAGS(PageTail(page), page);
	return 0;
}

static inline int thp_nr_pages(struct page *page)
{
	VM_BUG_ON_PGFLAGS(PageTail(page), page);
	return 1;
}

static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
{
	return false;
}

static inline bool transparent_hugepage_enabled(struct vm_area_struct *vma)
{
	return false;
}

static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
		unsigned long haddr)
{
	return false;
}

static inline void prep_transhuge_page(struct page *page) {}

static inline bool is_transparent_hugepage(struct page *page)
{
	return false;
}

#define transparent_hugepage_flags 0UL

#define thp_get_unmapped_area	NULL

static inline bool
can_split_huge_page(struct page *page, int *pextra_pins)
{
	BUILD_BUG();
	return false;
}
static inline int
split_huge_page_to_list(struct page *page, struct list_head *list)
{
	return 0;
}
static inline int split_huge_page(struct page *page)
{
	return 0;
}
static inline void deferred_split_huge_page(struct page *page) {}
#define split_huge_pmd(__vma, __pmd, __address)	\
	do { } while (0)

static inline void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
		unsigned long address, bool freeze, struct page *page) {}
static inline void split_huge_pmd_address(struct vm_area_struct *vma,
		unsigned long address, bool freeze, struct page *page) {}

#define split_huge_pud(__vma, __pmd, __address)	\
	do { } while (0)

static inline int hugepage_madvise(struct vm_area_struct *vma,
				   unsigned long *vm_flags, int advice)
{
	BUG();
	return 0;
}
static inline void vma_adjust_trans_huge(struct vm_area_struct *vma,
					 unsigned long start,
					 unsigned long end,
					 long adjust_next)
{
}
static inline int is_swap_pmd(pmd_t pmd)
{
	return 0;
}
static inline spinlock_t *pmd_trans_huge_lock(pmd_t *pmd,
		struct vm_area_struct *vma)
{
	return NULL;
}
static inline spinlock_t *pud_trans_huge_lock(pud_t *pud,
		struct vm_area_struct *vma)
{
	return NULL;
}

static inline vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf,
		pmd_t orig_pmd)
{
	return 0;
}

static inline bool is_huge_zero_page(struct page *page)
{
	return false;
}

static inline bool is_huge_zero_pud(pud_t pud)
{
	return false;
}

static inline void mm_put_huge_zero_page(struct mm_struct *mm)
{
	return;
}

static inline struct page *follow_devmap_pmd(struct vm_area_struct *vma,
	unsigned long addr, pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
{
	return NULL;
}

static inline struct page *follow_devmap_pud(struct vm_area_struct *vma,
	unsigned long addr, pud_t *pud, int flags, struct dev_pagemap **pgmap)
{
	return NULL;
}

static inline bool thp_migration_supported(void)
{
	return false;
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

/**
 * thp_size - Size of a transparent huge page.
 * @page: Head page of a transparent huge page.
 *
 * Return: Number of bytes in this page.
 */
static inline unsigned long thp_size(struct page *page)
{
	return PAGE_SIZE << thp_order(page);
}

#endif /* _LINUX_HUGE_MM_H */