xref: /openbmc/linux/mm/percpu.c (revision 4800cd83)
1 /*
2  * mm/percpu.c - percpu memory allocator
3  *
4  * Copyright (C) 2009		SUSE Linux Products GmbH
5  * Copyright (C) 2009		Tejun Heo <tj@kernel.org>
6  *
7  * This file is released under the GPLv2.
8  *
9  * This is percpu allocator which can handle both static and dynamic
10  * areas.  Percpu areas are allocated in chunks.  Each chunk is
11  * consisted of boot-time determined number of units and the first
12  * chunk is used for static percpu variables in the kernel image
13  * (special boot time alloc/init handling necessary as these areas
14  * need to be brought up before allocation services are running).
15  * Unit grows as necessary and all units grow or shrink in unison.
16  * When a chunk is filled up, another chunk is allocated.
17  *
18  *  c0                           c1                         c2
19  *  -------------------          -------------------        ------------
20  * | u0 | u1 | u2 | u3 |        | u0 | u1 | u2 | u3 |      | u0 | u1 | u
21  *  -------------------  ......  -------------------  ....  ------------
22  *
23  * Allocation is done in offset-size areas of single unit space.  Ie,
24  * an area of 512 bytes at 6k in c1 occupies 512 bytes at 6k of c1:u0,
25  * c1:u1, c1:u2 and c1:u3.  On UMA, units corresponds directly to
26  * cpus.  On NUMA, the mapping can be non-linear and even sparse.
27  * Percpu access can be done by configuring percpu base registers
28  * according to cpu to unit mapping and pcpu_unit_size.
29  *
30  * There are usually many small percpu allocations many of them being
31  * as small as 4 bytes.  The allocator organizes chunks into lists
32  * according to free size and tries to allocate from the fullest one.
33  * Each chunk keeps the maximum contiguous area size hint which is
34  * guaranteed to be equal to or larger than the maximum contiguous
35  * area in the chunk.  This helps the allocator not to iterate the
36  * chunk maps unnecessarily.
37  *
38  * Allocation state in each chunk is kept using an array of integers
39  * on chunk->map.  A positive value in the map represents a free
40  * region and negative allocated.  Allocation inside a chunk is done
41  * by scanning this map sequentially and serving the first matching
42  * entry.  This is mostly copied from the percpu_modalloc() allocator.
43  * Chunks can be determined from the address using the index field
44  * in the page struct. The index field contains a pointer to the chunk.
45  *
46  * To use this allocator, arch code should do the followings.
47  *
48  * - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate
49  *   regular address to percpu pointer and back if they need to be
50  *   different from the default
51  *
52  * - use pcpu_setup_first_chunk() during percpu area initialization to
53  *   setup the first chunk containing the kernel static percpu area
54  */
55 
56 #include <linux/bitmap.h>
57 #include <linux/bootmem.h>
58 #include <linux/err.h>
59 #include <linux/list.h>
60 #include <linux/log2.h>
61 #include <linux/mm.h>
62 #include <linux/module.h>
63 #include <linux/mutex.h>
64 #include <linux/percpu.h>
65 #include <linux/pfn.h>
66 #include <linux/slab.h>
67 #include <linux/spinlock.h>
68 #include <linux/vmalloc.h>
69 #include <linux/workqueue.h>
70 
71 #include <asm/cacheflush.h>
72 #include <asm/sections.h>
73 #include <asm/tlbflush.h>
74 #include <asm/io.h>
75 
76 #define PCPU_SLOT_BASE_SHIFT		5	/* 1-31 shares the same slot */
77 #define PCPU_DFL_MAP_ALLOC		16	/* start a map with 16 ents */
78 
79 #ifdef CONFIG_SMP
80 /* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
81 #ifndef __addr_to_pcpu_ptr
82 #define __addr_to_pcpu_ptr(addr)					\
83 	(void __percpu *)((unsigned long)(addr) -			\
84 			  (unsigned long)pcpu_base_addr	+		\
85 			  (unsigned long)__per_cpu_start)
86 #endif
87 #ifndef __pcpu_ptr_to_addr
88 #define __pcpu_ptr_to_addr(ptr)						\
89 	(void __force *)((unsigned long)(ptr) +				\
90 			 (unsigned long)pcpu_base_addr -		\
91 			 (unsigned long)__per_cpu_start)
92 #endif
93 #else	/* CONFIG_SMP */
94 /* on UP, it's always identity mapped */
95 #define __addr_to_pcpu_ptr(addr)	(void __percpu *)(addr)
96 #define __pcpu_ptr_to_addr(ptr)		(void __force *)(ptr)
97 #endif	/* CONFIG_SMP */
98 
99 struct pcpu_chunk {
100 	struct list_head	list;		/* linked to pcpu_slot lists */
101 	int			free_size;	/* free bytes in the chunk */
102 	int			contig_hint;	/* max contiguous size hint */
103 	void			*base_addr;	/* base address of this chunk */
104 	int			map_used;	/* # of map entries used */
105 	int			map_alloc;	/* # of map entries allocated */
106 	int			*map;		/* allocation map */
107 	void			*data;		/* chunk data */
108 	bool			immutable;	/* no [de]population allowed */
109 	unsigned long		populated[];	/* populated bitmap */
110 };
111 
112 static int pcpu_unit_pages __read_mostly;
113 static int pcpu_unit_size __read_mostly;
114 static int pcpu_nr_units __read_mostly;
115 static int pcpu_atom_size __read_mostly;
116 static int pcpu_nr_slots __read_mostly;
117 static size_t pcpu_chunk_struct_size __read_mostly;
118 
119 /* cpus with the lowest and highest unit numbers */
120 static unsigned int pcpu_first_unit_cpu __read_mostly;
121 static unsigned int pcpu_last_unit_cpu __read_mostly;
122 
123 /* the address of the first chunk which starts with the kernel static area */
124 void *pcpu_base_addr __read_mostly;
125 EXPORT_SYMBOL_GPL(pcpu_base_addr);
126 
127 static const int *pcpu_unit_map __read_mostly;		/* cpu -> unit */
128 const unsigned long *pcpu_unit_offsets __read_mostly;	/* cpu -> unit offset */
129 
130 /* group information, used for vm allocation */
131 static int pcpu_nr_groups __read_mostly;
132 static const unsigned long *pcpu_group_offsets __read_mostly;
133 static const size_t *pcpu_group_sizes __read_mostly;
134 
135 /*
136  * The first chunk which always exists.  Note that unlike other
137  * chunks, this one can be allocated and mapped in several different
138  * ways and thus often doesn't live in the vmalloc area.
139  */
140 static struct pcpu_chunk *pcpu_first_chunk;
141 
142 /*
143  * Optional reserved chunk.  This chunk reserves part of the first
144  * chunk and serves it for reserved allocations.  The amount of
145  * reserved offset is in pcpu_reserved_chunk_limit.  When reserved
146  * area doesn't exist, the following variables contain NULL and 0
147  * respectively.
148  */
149 static struct pcpu_chunk *pcpu_reserved_chunk;
150 static int pcpu_reserved_chunk_limit;
151 
152 /*
153  * Synchronization rules.
154  *
155  * There are two locks - pcpu_alloc_mutex and pcpu_lock.  The former
156  * protects allocation/reclaim paths, chunks, populated bitmap and
157  * vmalloc mapping.  The latter is a spinlock and protects the index
158  * data structures - chunk slots, chunks and area maps in chunks.
159  *
160  * During allocation, pcpu_alloc_mutex is kept locked all the time and
161  * pcpu_lock is grabbed and released as necessary.  All actual memory
162  * allocations are done using GFP_KERNEL with pcpu_lock released.  In
163  * general, percpu memory can't be allocated with irq off but
164  * irqsave/restore are still used in alloc path so that it can be used
165  * from early init path - sched_init() specifically.
166  *
167  * Free path accesses and alters only the index data structures, so it
168  * can be safely called from atomic context.  When memory needs to be
169  * returned to the system, free path schedules reclaim_work which
170  * grabs both pcpu_alloc_mutex and pcpu_lock, unlinks chunks to be
171  * reclaimed, release both locks and frees the chunks.  Note that it's
172  * necessary to grab both locks to remove a chunk from circulation as
173  * allocation path might be referencing the chunk with only
174  * pcpu_alloc_mutex locked.
175  */
176 static DEFINE_MUTEX(pcpu_alloc_mutex);	/* protects whole alloc and reclaim */
177 static DEFINE_SPINLOCK(pcpu_lock);	/* protects index data structures */
178 
179 static struct list_head *pcpu_slot __read_mostly; /* chunk list slots */
180 
181 /* reclaim work to release fully free chunks, scheduled from free path */
182 static void pcpu_reclaim(struct work_struct *work);
183 static DECLARE_WORK(pcpu_reclaim_work, pcpu_reclaim);
184 
185 static bool pcpu_addr_in_first_chunk(void *addr)
186 {
187 	void *first_start = pcpu_first_chunk->base_addr;
188 
189 	return addr >= first_start && addr < first_start + pcpu_unit_size;
190 }
191 
192 static bool pcpu_addr_in_reserved_chunk(void *addr)
193 {
194 	void *first_start = pcpu_first_chunk->base_addr;
195 
196 	return addr >= first_start &&
197 		addr < first_start + pcpu_reserved_chunk_limit;
198 }
199 
200 static int __pcpu_size_to_slot(int size)
201 {
202 	int highbit = fls(size);	/* size is in bytes */
203 	return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1);
204 }
205 
206 static int pcpu_size_to_slot(int size)
207 {
208 	if (size == pcpu_unit_size)
209 		return pcpu_nr_slots - 1;
210 	return __pcpu_size_to_slot(size);
211 }
212 
213 static int pcpu_chunk_slot(const struct pcpu_chunk *chunk)
214 {
215 	if (chunk->free_size < sizeof(int) || chunk->contig_hint < sizeof(int))
216 		return 0;
217 
218 	return pcpu_size_to_slot(chunk->free_size);
219 }
220 
221 /* set the pointer to a chunk in a page struct */
222 static void pcpu_set_page_chunk(struct page *page, struct pcpu_chunk *pcpu)
223 {
224 	page->index = (unsigned long)pcpu;
225 }
226 
227 /* obtain pointer to a chunk from a page struct */
228 static struct pcpu_chunk *pcpu_get_page_chunk(struct page *page)
229 {
230 	return (struct pcpu_chunk *)page->index;
231 }
232 
233 static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx)
234 {
235 	return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx;
236 }
237 
238 static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
239 				     unsigned int cpu, int page_idx)
240 {
241 	return (unsigned long)chunk->base_addr + pcpu_unit_offsets[cpu] +
242 		(page_idx << PAGE_SHIFT);
243 }
244 
245 static void __maybe_unused pcpu_next_unpop(struct pcpu_chunk *chunk,
246 					   int *rs, int *re, int end)
247 {
248 	*rs = find_next_zero_bit(chunk->populated, end, *rs);
249 	*re = find_next_bit(chunk->populated, end, *rs + 1);
250 }
251 
252 static void __maybe_unused pcpu_next_pop(struct pcpu_chunk *chunk,
253 					 int *rs, int *re, int end)
254 {
255 	*rs = find_next_bit(chunk->populated, end, *rs);
256 	*re = find_next_zero_bit(chunk->populated, end, *rs + 1);
257 }
258 
259 /*
260  * (Un)populated page region iterators.  Iterate over (un)populated
261  * page regions between @start and @end in @chunk.  @rs and @re should
262  * be integer variables and will be set to start and end page index of
263  * the current region.
264  */
265 #define pcpu_for_each_unpop_region(chunk, rs, re, start, end)		    \
266 	for ((rs) = (start), pcpu_next_unpop((chunk), &(rs), &(re), (end)); \
267 	     (rs) < (re);						    \
268 	     (rs) = (re) + 1, pcpu_next_unpop((chunk), &(rs), &(re), (end)))
269 
270 #define pcpu_for_each_pop_region(chunk, rs, re, start, end)		    \
271 	for ((rs) = (start), pcpu_next_pop((chunk), &(rs), &(re), (end));   \
272 	     (rs) < (re);						    \
273 	     (rs) = (re) + 1, pcpu_next_pop((chunk), &(rs), &(re), (end)))
274 
275 /**
276  * pcpu_mem_alloc - allocate memory
277  * @size: bytes to allocate
278  *
279  * Allocate @size bytes.  If @size is smaller than PAGE_SIZE,
280  * kzalloc() is used; otherwise, vmalloc() is used.  The returned
281  * memory is always zeroed.
282  *
283  * CONTEXT:
284  * Does GFP_KERNEL allocation.
285  *
286  * RETURNS:
287  * Pointer to the allocated area on success, NULL on failure.
288  */
289 static void *pcpu_mem_alloc(size_t size)
290 {
291 	if (WARN_ON_ONCE(!slab_is_available()))
292 		return NULL;
293 
294 	if (size <= PAGE_SIZE)
295 		return kzalloc(size, GFP_KERNEL);
296 	else
297 		return vzalloc(size);
298 }
299 
300 /**
301  * pcpu_mem_free - free memory
302  * @ptr: memory to free
303  * @size: size of the area
304  *
305  * Free @ptr.  @ptr should have been allocated using pcpu_mem_alloc().
306  */
307 static void pcpu_mem_free(void *ptr, size_t size)
308 {
309 	if (size <= PAGE_SIZE)
310 		kfree(ptr);
311 	else
312 		vfree(ptr);
313 }
314 
315 /**
316  * pcpu_chunk_relocate - put chunk in the appropriate chunk slot
317  * @chunk: chunk of interest
318  * @oslot: the previous slot it was on
319  *
320  * This function is called after an allocation or free changed @chunk.
321  * New slot according to the changed state is determined and @chunk is
322  * moved to the slot.  Note that the reserved chunk is never put on
323  * chunk slots.
324  *
325  * CONTEXT:
326  * pcpu_lock.
327  */
328 static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
329 {
330 	int nslot = pcpu_chunk_slot(chunk);
331 
332 	if (chunk != pcpu_reserved_chunk && oslot != nslot) {
333 		if (oslot < nslot)
334 			list_move(&chunk->list, &pcpu_slot[nslot]);
335 		else
336 			list_move_tail(&chunk->list, &pcpu_slot[nslot]);
337 	}
338 }
339 
340 /**
341  * pcpu_need_to_extend - determine whether chunk area map needs to be extended
342  * @chunk: chunk of interest
343  *
344  * Determine whether area map of @chunk needs to be extended to
345  * accomodate a new allocation.
346  *
347  * CONTEXT:
348  * pcpu_lock.
349  *
350  * RETURNS:
351  * New target map allocation length if extension is necessary, 0
352  * otherwise.
353  */
354 static int pcpu_need_to_extend(struct pcpu_chunk *chunk)
355 {
356 	int new_alloc;
357 
358 	if (chunk->map_alloc >= chunk->map_used + 2)
359 		return 0;
360 
361 	new_alloc = PCPU_DFL_MAP_ALLOC;
362 	while (new_alloc < chunk->map_used + 2)
363 		new_alloc *= 2;
364 
365 	return new_alloc;
366 }
367 
368 /**
369  * pcpu_extend_area_map - extend area map of a chunk
370  * @chunk: chunk of interest
371  * @new_alloc: new target allocation length of the area map
372  *
373  * Extend area map of @chunk to have @new_alloc entries.
374  *
375  * CONTEXT:
376  * Does GFP_KERNEL allocation.  Grabs and releases pcpu_lock.
377  *
378  * RETURNS:
379  * 0 on success, -errno on failure.
380  */
381 static int pcpu_extend_area_map(struct pcpu_chunk *chunk, int new_alloc)
382 {
383 	int *old = NULL, *new = NULL;
384 	size_t old_size = 0, new_size = new_alloc * sizeof(new[0]);
385 	unsigned long flags;
386 
387 	new = pcpu_mem_alloc(new_size);
388 	if (!new)
389 		return -ENOMEM;
390 
391 	/* acquire pcpu_lock and switch to new area map */
392 	spin_lock_irqsave(&pcpu_lock, flags);
393 
394 	if (new_alloc <= chunk->map_alloc)
395 		goto out_unlock;
396 
397 	old_size = chunk->map_alloc * sizeof(chunk->map[0]);
398 	old = chunk->map;
399 
400 	memcpy(new, old, old_size);
401 
402 	chunk->map_alloc = new_alloc;
403 	chunk->map = new;
404 	new = NULL;
405 
406 out_unlock:
407 	spin_unlock_irqrestore(&pcpu_lock, flags);
408 
409 	/*
410 	 * pcpu_mem_free() might end up calling vfree() which uses
411 	 * IRQ-unsafe lock and thus can't be called under pcpu_lock.
412 	 */
413 	pcpu_mem_free(old, old_size);
414 	pcpu_mem_free(new, new_size);
415 
416 	return 0;
417 }
418 
419 /**
420  * pcpu_split_block - split a map block
421  * @chunk: chunk of interest
422  * @i: index of map block to split
423  * @head: head size in bytes (can be 0)
424  * @tail: tail size in bytes (can be 0)
425  *
426  * Split the @i'th map block into two or three blocks.  If @head is
427  * non-zero, @head bytes block is inserted before block @i moving it
428  * to @i+1 and reducing its size by @head bytes.
429  *
430  * If @tail is non-zero, the target block, which can be @i or @i+1
431  * depending on @head, is reduced by @tail bytes and @tail byte block
432  * is inserted after the target block.
433  *
434  * @chunk->map must have enough free slots to accomodate the split.
435  *
436  * CONTEXT:
437  * pcpu_lock.
438  */
439 static void pcpu_split_block(struct pcpu_chunk *chunk, int i,
440 			     int head, int tail)
441 {
442 	int nr_extra = !!head + !!tail;
443 
444 	BUG_ON(chunk->map_alloc < chunk->map_used + nr_extra);
445 
446 	/* insert new subblocks */
447 	memmove(&chunk->map[i + nr_extra], &chunk->map[i],
448 		sizeof(chunk->map[0]) * (chunk->map_used - i));
449 	chunk->map_used += nr_extra;
450 
451 	if (head) {
452 		chunk->map[i + 1] = chunk->map[i] - head;
453 		chunk->map[i++] = head;
454 	}
455 	if (tail) {
456 		chunk->map[i++] -= tail;
457 		chunk->map[i] = tail;
458 	}
459 }
460 
461 /**
462  * pcpu_alloc_area - allocate area from a pcpu_chunk
463  * @chunk: chunk of interest
464  * @size: wanted size in bytes
465  * @align: wanted align
466  *
467  * Try to allocate @size bytes area aligned at @align from @chunk.
468  * Note that this function only allocates the offset.  It doesn't
469  * populate or map the area.
470  *
471  * @chunk->map must have at least two free slots.
472  *
473  * CONTEXT:
474  * pcpu_lock.
475  *
476  * RETURNS:
477  * Allocated offset in @chunk on success, -1 if no matching area is
478  * found.
479  */
480 static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align)
481 {
482 	int oslot = pcpu_chunk_slot(chunk);
483 	int max_contig = 0;
484 	int i, off;
485 
486 	for (i = 0, off = 0; i < chunk->map_used; off += abs(chunk->map[i++])) {
487 		bool is_last = i + 1 == chunk->map_used;
488 		int head, tail;
489 
490 		/* extra for alignment requirement */
491 		head = ALIGN(off, align) - off;
492 		BUG_ON(i == 0 && head != 0);
493 
494 		if (chunk->map[i] < 0)
495 			continue;
496 		if (chunk->map[i] < head + size) {
497 			max_contig = max(chunk->map[i], max_contig);
498 			continue;
499 		}
500 
501 		/*
502 		 * If head is small or the previous block is free,
503 		 * merge'em.  Note that 'small' is defined as smaller
504 		 * than sizeof(int), which is very small but isn't too
505 		 * uncommon for percpu allocations.
506 		 */
507 		if (head && (head < sizeof(int) || chunk->map[i - 1] > 0)) {
508 			if (chunk->map[i - 1] > 0)
509 				chunk->map[i - 1] += head;
510 			else {
511 				chunk->map[i - 1] -= head;
512 				chunk->free_size -= head;
513 			}
514 			chunk->map[i] -= head;
515 			off += head;
516 			head = 0;
517 		}
518 
519 		/* if tail is small, just keep it around */
520 		tail = chunk->map[i] - head - size;
521 		if (tail < sizeof(int))
522 			tail = 0;
523 
524 		/* split if warranted */
525 		if (head || tail) {
526 			pcpu_split_block(chunk, i, head, tail);
527 			if (head) {
528 				i++;
529 				off += head;
530 				max_contig = max(chunk->map[i - 1], max_contig);
531 			}
532 			if (tail)
533 				max_contig = max(chunk->map[i + 1], max_contig);
534 		}
535 
536 		/* update hint and mark allocated */
537 		if (is_last)
538 			chunk->contig_hint = max_contig; /* fully scanned */
539 		else
540 			chunk->contig_hint = max(chunk->contig_hint,
541 						 max_contig);
542 
543 		chunk->free_size -= chunk->map[i];
544 		chunk->map[i] = -chunk->map[i];
545 
546 		pcpu_chunk_relocate(chunk, oslot);
547 		return off;
548 	}
549 
550 	chunk->contig_hint = max_contig;	/* fully scanned */
551 	pcpu_chunk_relocate(chunk, oslot);
552 
553 	/* tell the upper layer that this chunk has no matching area */
554 	return -1;
555 }
556 
557 /**
558  * pcpu_free_area - free area to a pcpu_chunk
559  * @chunk: chunk of interest
560  * @freeme: offset of area to free
561  *
562  * Free area starting from @freeme to @chunk.  Note that this function
563  * only modifies the allocation map.  It doesn't depopulate or unmap
564  * the area.
565  *
566  * CONTEXT:
567  * pcpu_lock.
568  */
569 static void pcpu_free_area(struct pcpu_chunk *chunk, int freeme)
570 {
571 	int oslot = pcpu_chunk_slot(chunk);
572 	int i, off;
573 
574 	for (i = 0, off = 0; i < chunk->map_used; off += abs(chunk->map[i++]))
575 		if (off == freeme)
576 			break;
577 	BUG_ON(off != freeme);
578 	BUG_ON(chunk->map[i] > 0);
579 
580 	chunk->map[i] = -chunk->map[i];
581 	chunk->free_size += chunk->map[i];
582 
583 	/* merge with previous? */
584 	if (i > 0 && chunk->map[i - 1] >= 0) {
585 		chunk->map[i - 1] += chunk->map[i];
586 		chunk->map_used--;
587 		memmove(&chunk->map[i], &chunk->map[i + 1],
588 			(chunk->map_used - i) * sizeof(chunk->map[0]));
589 		i--;
590 	}
591 	/* merge with next? */
592 	if (i + 1 < chunk->map_used && chunk->map[i + 1] >= 0) {
593 		chunk->map[i] += chunk->map[i + 1];
594 		chunk->map_used--;
595 		memmove(&chunk->map[i + 1], &chunk->map[i + 2],
596 			(chunk->map_used - (i + 1)) * sizeof(chunk->map[0]));
597 	}
598 
599 	chunk->contig_hint = max(chunk->map[i], chunk->contig_hint);
600 	pcpu_chunk_relocate(chunk, oslot);
601 }
602 
603 static struct pcpu_chunk *pcpu_alloc_chunk(void)
604 {
605 	struct pcpu_chunk *chunk;
606 
607 	chunk = pcpu_mem_alloc(pcpu_chunk_struct_size);
608 	if (!chunk)
609 		return NULL;
610 
611 	chunk->map = pcpu_mem_alloc(PCPU_DFL_MAP_ALLOC * sizeof(chunk->map[0]));
612 	if (!chunk->map) {
613 		kfree(chunk);
614 		return NULL;
615 	}
616 
617 	chunk->map_alloc = PCPU_DFL_MAP_ALLOC;
618 	chunk->map[chunk->map_used++] = pcpu_unit_size;
619 
620 	INIT_LIST_HEAD(&chunk->list);
621 	chunk->free_size = pcpu_unit_size;
622 	chunk->contig_hint = pcpu_unit_size;
623 
624 	return chunk;
625 }
626 
627 static void pcpu_free_chunk(struct pcpu_chunk *chunk)
628 {
629 	if (!chunk)
630 		return;
631 	pcpu_mem_free(chunk->map, chunk->map_alloc * sizeof(chunk->map[0]));
632 	kfree(chunk);
633 }
634 
635 /*
636  * Chunk management implementation.
637  *
638  * To allow different implementations, chunk alloc/free and
639  * [de]population are implemented in a separate file which is pulled
640  * into this file and compiled together.  The following functions
641  * should be implemented.
642  *
643  * pcpu_populate_chunk		- populate the specified range of a chunk
644  * pcpu_depopulate_chunk	- depopulate the specified range of a chunk
645  * pcpu_create_chunk		- create a new chunk
646  * pcpu_destroy_chunk		- destroy a chunk, always preceded by full depop
647  * pcpu_addr_to_page		- translate address to physical address
648  * pcpu_verify_alloc_info	- check alloc_info is acceptable during init
649  */
650 static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size);
651 static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size);
652 static struct pcpu_chunk *pcpu_create_chunk(void);
653 static void pcpu_destroy_chunk(struct pcpu_chunk *chunk);
654 static struct page *pcpu_addr_to_page(void *addr);
655 static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai);
656 
657 #ifdef CONFIG_NEED_PER_CPU_KM
658 #include "percpu-km.c"
659 #else
660 #include "percpu-vm.c"
661 #endif
662 
663 /**
664  * pcpu_chunk_addr_search - determine chunk containing specified address
665  * @addr: address for which the chunk needs to be determined.
666  *
667  * RETURNS:
668  * The address of the found chunk.
669  */
670 static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
671 {
672 	/* is it in the first chunk? */
673 	if (pcpu_addr_in_first_chunk(addr)) {
674 		/* is it in the reserved area? */
675 		if (pcpu_addr_in_reserved_chunk(addr))
676 			return pcpu_reserved_chunk;
677 		return pcpu_first_chunk;
678 	}
679 
680 	/*
681 	 * The address is relative to unit0 which might be unused and
682 	 * thus unmapped.  Offset the address to the unit space of the
683 	 * current processor before looking it up in the vmalloc
684 	 * space.  Note that any possible cpu id can be used here, so
685 	 * there's no need to worry about preemption or cpu hotplug.
686 	 */
687 	addr += pcpu_unit_offsets[raw_smp_processor_id()];
688 	return pcpu_get_page_chunk(pcpu_addr_to_page(addr));
689 }
690 
691 /**
692  * pcpu_alloc - the percpu allocator
693  * @size: size of area to allocate in bytes
694  * @align: alignment of area (max PAGE_SIZE)
695  * @reserved: allocate from the reserved chunk if available
696  *
697  * Allocate percpu area of @size bytes aligned at @align.
698  *
699  * CONTEXT:
700  * Does GFP_KERNEL allocation.
701  *
702  * RETURNS:
703  * Percpu pointer to the allocated area on success, NULL on failure.
704  */
705 static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved)
706 {
707 	static int warn_limit = 10;
708 	struct pcpu_chunk *chunk;
709 	const char *err;
710 	int slot, off, new_alloc;
711 	unsigned long flags;
712 
713 	if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
714 		WARN(true, "illegal size (%zu) or align (%zu) for "
715 		     "percpu allocation\n", size, align);
716 		return NULL;
717 	}
718 
719 	mutex_lock(&pcpu_alloc_mutex);
720 	spin_lock_irqsave(&pcpu_lock, flags);
721 
722 	/* serve reserved allocations from the reserved chunk if available */
723 	if (reserved && pcpu_reserved_chunk) {
724 		chunk = pcpu_reserved_chunk;
725 
726 		if (size > chunk->contig_hint) {
727 			err = "alloc from reserved chunk failed";
728 			goto fail_unlock;
729 		}
730 
731 		while ((new_alloc = pcpu_need_to_extend(chunk))) {
732 			spin_unlock_irqrestore(&pcpu_lock, flags);
733 			if (pcpu_extend_area_map(chunk, new_alloc) < 0) {
734 				err = "failed to extend area map of reserved chunk";
735 				goto fail_unlock_mutex;
736 			}
737 			spin_lock_irqsave(&pcpu_lock, flags);
738 		}
739 
740 		off = pcpu_alloc_area(chunk, size, align);
741 		if (off >= 0)
742 			goto area_found;
743 
744 		err = "alloc from reserved chunk failed";
745 		goto fail_unlock;
746 	}
747 
748 restart:
749 	/* search through normal chunks */
750 	for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) {
751 		list_for_each_entry(chunk, &pcpu_slot[slot], list) {
752 			if (size > chunk->contig_hint)
753 				continue;
754 
755 			new_alloc = pcpu_need_to_extend(chunk);
756 			if (new_alloc) {
757 				spin_unlock_irqrestore(&pcpu_lock, flags);
758 				if (pcpu_extend_area_map(chunk,
759 							 new_alloc) < 0) {
760 					err = "failed to extend area map";
761 					goto fail_unlock_mutex;
762 				}
763 				spin_lock_irqsave(&pcpu_lock, flags);
764 				/*
765 				 * pcpu_lock has been dropped, need to
766 				 * restart cpu_slot list walking.
767 				 */
768 				goto restart;
769 			}
770 
771 			off = pcpu_alloc_area(chunk, size, align);
772 			if (off >= 0)
773 				goto area_found;
774 		}
775 	}
776 
777 	/* hmmm... no space left, create a new chunk */
778 	spin_unlock_irqrestore(&pcpu_lock, flags);
779 
780 	chunk = pcpu_create_chunk();
781 	if (!chunk) {
782 		err = "failed to allocate new chunk";
783 		goto fail_unlock_mutex;
784 	}
785 
786 	spin_lock_irqsave(&pcpu_lock, flags);
787 	pcpu_chunk_relocate(chunk, -1);
788 	goto restart;
789 
790 area_found:
791 	spin_unlock_irqrestore(&pcpu_lock, flags);
792 
793 	/* populate, map and clear the area */
794 	if (pcpu_populate_chunk(chunk, off, size)) {
795 		spin_lock_irqsave(&pcpu_lock, flags);
796 		pcpu_free_area(chunk, off);
797 		err = "failed to populate";
798 		goto fail_unlock;
799 	}
800 
801 	mutex_unlock(&pcpu_alloc_mutex);
802 
803 	/* return address relative to base address */
804 	return __addr_to_pcpu_ptr(chunk->base_addr + off);
805 
806 fail_unlock:
807 	spin_unlock_irqrestore(&pcpu_lock, flags);
808 fail_unlock_mutex:
809 	mutex_unlock(&pcpu_alloc_mutex);
810 	if (warn_limit) {
811 		pr_warning("PERCPU: allocation failed, size=%zu align=%zu, "
812 			   "%s\n", size, align, err);
813 		dump_stack();
814 		if (!--warn_limit)
815 			pr_info("PERCPU: limit reached, disable warning\n");
816 	}
817 	return NULL;
818 }
819 
820 /**
821  * __alloc_percpu - allocate dynamic percpu area
822  * @size: size of area to allocate in bytes
823  * @align: alignment of area (max PAGE_SIZE)
824  *
825  * Allocate zero-filled percpu area of @size bytes aligned at @align.
826  * Might sleep.  Might trigger writeouts.
827  *
828  * CONTEXT:
829  * Does GFP_KERNEL allocation.
830  *
831  * RETURNS:
832  * Percpu pointer to the allocated area on success, NULL on failure.
833  */
834 void __percpu *__alloc_percpu(size_t size, size_t align)
835 {
836 	return pcpu_alloc(size, align, false);
837 }
838 EXPORT_SYMBOL_GPL(__alloc_percpu);
839 
840 /**
841  * __alloc_reserved_percpu - allocate reserved percpu area
842  * @size: size of area to allocate in bytes
843  * @align: alignment of area (max PAGE_SIZE)
844  *
845  * Allocate zero-filled percpu area of @size bytes aligned at @align
846  * from reserved percpu area if arch has set it up; otherwise,
847  * allocation is served from the same dynamic area.  Might sleep.
848  * Might trigger writeouts.
849  *
850  * CONTEXT:
851  * Does GFP_KERNEL allocation.
852  *
853  * RETURNS:
854  * Percpu pointer to the allocated area on success, NULL on failure.
855  */
856 void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
857 {
858 	return pcpu_alloc(size, align, true);
859 }
860 
861 /**
862  * pcpu_reclaim - reclaim fully free chunks, workqueue function
863  * @work: unused
864  *
865  * Reclaim all fully free chunks except for the first one.
866  *
867  * CONTEXT:
868  * workqueue context.
869  */
870 static void pcpu_reclaim(struct work_struct *work)
871 {
872 	LIST_HEAD(todo);
873 	struct list_head *head = &pcpu_slot[pcpu_nr_slots - 1];
874 	struct pcpu_chunk *chunk, *next;
875 
876 	mutex_lock(&pcpu_alloc_mutex);
877 	spin_lock_irq(&pcpu_lock);
878 
879 	list_for_each_entry_safe(chunk, next, head, list) {
880 		WARN_ON(chunk->immutable);
881 
882 		/* spare the first one */
883 		if (chunk == list_first_entry(head, struct pcpu_chunk, list))
884 			continue;
885 
886 		list_move(&chunk->list, &todo);
887 	}
888 
889 	spin_unlock_irq(&pcpu_lock);
890 
891 	list_for_each_entry_safe(chunk, next, &todo, list) {
892 		pcpu_depopulate_chunk(chunk, 0, pcpu_unit_size);
893 		pcpu_destroy_chunk(chunk);
894 	}
895 
896 	mutex_unlock(&pcpu_alloc_mutex);
897 }
898 
899 /**
900  * free_percpu - free percpu area
901  * @ptr: pointer to area to free
902  *
903  * Free percpu area @ptr.
904  *
905  * CONTEXT:
906  * Can be called from atomic context.
907  */
908 void free_percpu(void __percpu *ptr)
909 {
910 	void *addr;
911 	struct pcpu_chunk *chunk;
912 	unsigned long flags;
913 	int off;
914 
915 	if (!ptr)
916 		return;
917 
918 	addr = __pcpu_ptr_to_addr(ptr);
919 
920 	spin_lock_irqsave(&pcpu_lock, flags);
921 
922 	chunk = pcpu_chunk_addr_search(addr);
923 	off = addr - chunk->base_addr;
924 
925 	pcpu_free_area(chunk, off);
926 
927 	/* if there are more than one fully free chunks, wake up grim reaper */
928 	if (chunk->free_size == pcpu_unit_size) {
929 		struct pcpu_chunk *pos;
930 
931 		list_for_each_entry(pos, &pcpu_slot[pcpu_nr_slots - 1], list)
932 			if (pos != chunk) {
933 				schedule_work(&pcpu_reclaim_work);
934 				break;
935 			}
936 	}
937 
938 	spin_unlock_irqrestore(&pcpu_lock, flags);
939 }
940 EXPORT_SYMBOL_GPL(free_percpu);
941 
942 /**
943  * is_kernel_percpu_address - test whether address is from static percpu area
944  * @addr: address to test
945  *
946  * Test whether @addr belongs to in-kernel static percpu area.  Module
947  * static percpu areas are not considered.  For those, use
948  * is_module_percpu_address().
949  *
950  * RETURNS:
951  * %true if @addr is from in-kernel static percpu area, %false otherwise.
952  */
953 bool is_kernel_percpu_address(unsigned long addr)
954 {
955 #ifdef CONFIG_SMP
956 	const size_t static_size = __per_cpu_end - __per_cpu_start;
957 	void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
958 	unsigned int cpu;
959 
960 	for_each_possible_cpu(cpu) {
961 		void *start = per_cpu_ptr(base, cpu);
962 
963 		if ((void *)addr >= start && (void *)addr < start + static_size)
964 			return true;
965         }
966 #endif
967 	/* on UP, can't distinguish from other static vars, always false */
968 	return false;
969 }
970 
971 /**
972  * per_cpu_ptr_to_phys - convert translated percpu address to physical address
973  * @addr: the address to be converted to physical address
974  *
975  * Given @addr which is dereferenceable address obtained via one of
976  * percpu access macros, this function translates it into its physical
977  * address.  The caller is responsible for ensuring @addr stays valid
978  * until this function finishes.
979  *
980  * RETURNS:
981  * The physical address for @addr.
982  */
983 phys_addr_t per_cpu_ptr_to_phys(void *addr)
984 {
985 	void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
986 	bool in_first_chunk = false;
987 	unsigned long first_start, first_end;
988 	unsigned int cpu;
989 
990 	/*
991 	 * The following test on first_start/end isn't strictly
992 	 * necessary but will speed up lookups of addresses which
993 	 * aren't in the first chunk.
994 	 */
995 	first_start = pcpu_chunk_addr(pcpu_first_chunk, pcpu_first_unit_cpu, 0);
996 	first_end = pcpu_chunk_addr(pcpu_first_chunk, pcpu_last_unit_cpu,
997 				    pcpu_unit_pages);
998 	if ((unsigned long)addr >= first_start &&
999 	    (unsigned long)addr < first_end) {
1000 		for_each_possible_cpu(cpu) {
1001 			void *start = per_cpu_ptr(base, cpu);
1002 
1003 			if (addr >= start && addr < start + pcpu_unit_size) {
1004 				in_first_chunk = true;
1005 				break;
1006 			}
1007 		}
1008 	}
1009 
1010 	if (in_first_chunk) {
1011 		if ((unsigned long)addr < VMALLOC_START ||
1012 		    (unsigned long)addr >= VMALLOC_END)
1013 			return __pa(addr);
1014 		else
1015 			return page_to_phys(vmalloc_to_page(addr));
1016 	} else
1017 		return page_to_phys(pcpu_addr_to_page(addr));
1018 }
1019 
1020 /**
1021  * pcpu_alloc_alloc_info - allocate percpu allocation info
1022  * @nr_groups: the number of groups
1023  * @nr_units: the number of units
1024  *
1025  * Allocate ai which is large enough for @nr_groups groups containing
1026  * @nr_units units.  The returned ai's groups[0].cpu_map points to the
1027  * cpu_map array which is long enough for @nr_units and filled with
1028  * NR_CPUS.  It's the caller's responsibility to initialize cpu_map
1029  * pointer of other groups.
1030  *
1031  * RETURNS:
1032  * Pointer to the allocated pcpu_alloc_info on success, NULL on
1033  * failure.
1034  */
1035 struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
1036 						      int nr_units)
1037 {
1038 	struct pcpu_alloc_info *ai;
1039 	size_t base_size, ai_size;
1040 	void *ptr;
1041 	int unit;
1042 
1043 	base_size = ALIGN(sizeof(*ai) + nr_groups * sizeof(ai->groups[0]),
1044 			  __alignof__(ai->groups[0].cpu_map[0]));
1045 	ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]);
1046 
1047 	ptr = alloc_bootmem_nopanic(PFN_ALIGN(ai_size));
1048 	if (!ptr)
1049 		return NULL;
1050 	ai = ptr;
1051 	ptr += base_size;
1052 
1053 	ai->groups[0].cpu_map = ptr;
1054 
1055 	for (unit = 0; unit < nr_units; unit++)
1056 		ai->groups[0].cpu_map[unit] = NR_CPUS;
1057 
1058 	ai->nr_groups = nr_groups;
1059 	ai->__ai_size = PFN_ALIGN(ai_size);
1060 
1061 	return ai;
1062 }
1063 
1064 /**
1065  * pcpu_free_alloc_info - free percpu allocation info
1066  * @ai: pcpu_alloc_info to free
1067  *
1068  * Free @ai which was allocated by pcpu_alloc_alloc_info().
1069  */
1070 void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
1071 {
1072 	free_bootmem(__pa(ai), ai->__ai_size);
1073 }
1074 
1075 /**
1076  * pcpu_dump_alloc_info - print out information about pcpu_alloc_info
1077  * @lvl: loglevel
1078  * @ai: allocation info to dump
1079  *
1080  * Print out information about @ai using loglevel @lvl.
1081  */
1082 static void pcpu_dump_alloc_info(const char *lvl,
1083 				 const struct pcpu_alloc_info *ai)
1084 {
1085 	int group_width = 1, cpu_width = 1, width;
1086 	char empty_str[] = "--------";
1087 	int alloc = 0, alloc_end = 0;
1088 	int group, v;
1089 	int upa, apl;	/* units per alloc, allocs per line */
1090 
1091 	v = ai->nr_groups;
1092 	while (v /= 10)
1093 		group_width++;
1094 
1095 	v = num_possible_cpus();
1096 	while (v /= 10)
1097 		cpu_width++;
1098 	empty_str[min_t(int, cpu_width, sizeof(empty_str) - 1)] = '\0';
1099 
1100 	upa = ai->alloc_size / ai->unit_size;
1101 	width = upa * (cpu_width + 1) + group_width + 3;
1102 	apl = rounddown_pow_of_two(max(60 / width, 1));
1103 
1104 	printk("%spcpu-alloc: s%zu r%zu d%zu u%zu alloc=%zu*%zu",
1105 	       lvl, ai->static_size, ai->reserved_size, ai->dyn_size,
1106 	       ai->unit_size, ai->alloc_size / ai->atom_size, ai->atom_size);
1107 
1108 	for (group = 0; group < ai->nr_groups; group++) {
1109 		const struct pcpu_group_info *gi = &ai->groups[group];
1110 		int unit = 0, unit_end = 0;
1111 
1112 		BUG_ON(gi->nr_units % upa);
1113 		for (alloc_end += gi->nr_units / upa;
1114 		     alloc < alloc_end; alloc++) {
1115 			if (!(alloc % apl)) {
1116 				printk("\n");
1117 				printk("%spcpu-alloc: ", lvl);
1118 			}
1119 			printk("[%0*d] ", group_width, group);
1120 
1121 			for (unit_end += upa; unit < unit_end; unit++)
1122 				if (gi->cpu_map[unit] != NR_CPUS)
1123 					printk("%0*d ", cpu_width,
1124 					       gi->cpu_map[unit]);
1125 				else
1126 					printk("%s ", empty_str);
1127 		}
1128 	}
1129 	printk("\n");
1130 }
1131 
1132 /**
1133  * pcpu_setup_first_chunk - initialize the first percpu chunk
1134  * @ai: pcpu_alloc_info describing how to percpu area is shaped
1135  * @base_addr: mapped address
1136  *
1137  * Initialize the first percpu chunk which contains the kernel static
1138  * perpcu area.  This function is to be called from arch percpu area
1139  * setup path.
1140  *
1141  * @ai contains all information necessary to initialize the first
1142  * chunk and prime the dynamic percpu allocator.
1143  *
1144  * @ai->static_size is the size of static percpu area.
1145  *
1146  * @ai->reserved_size, if non-zero, specifies the amount of bytes to
1147  * reserve after the static area in the first chunk.  This reserves
1148  * the first chunk such that it's available only through reserved
1149  * percpu allocation.  This is primarily used to serve module percpu
1150  * static areas on architectures where the addressing model has
1151  * limited offset range for symbol relocations to guarantee module
1152  * percpu symbols fall inside the relocatable range.
1153  *
1154  * @ai->dyn_size determines the number of bytes available for dynamic
1155  * allocation in the first chunk.  The area between @ai->static_size +
1156  * @ai->reserved_size + @ai->dyn_size and @ai->unit_size is unused.
1157  *
1158  * @ai->unit_size specifies unit size and must be aligned to PAGE_SIZE
1159  * and equal to or larger than @ai->static_size + @ai->reserved_size +
1160  * @ai->dyn_size.
1161  *
1162  * @ai->atom_size is the allocation atom size and used as alignment
1163  * for vm areas.
1164  *
1165  * @ai->alloc_size is the allocation size and always multiple of
1166  * @ai->atom_size.  This is larger than @ai->atom_size if
1167  * @ai->unit_size is larger than @ai->atom_size.
1168  *
1169  * @ai->nr_groups and @ai->groups describe virtual memory layout of
1170  * percpu areas.  Units which should be colocated are put into the
1171  * same group.  Dynamic VM areas will be allocated according to these
1172  * groupings.  If @ai->nr_groups is zero, a single group containing
1173  * all units is assumed.
1174  *
1175  * The caller should have mapped the first chunk at @base_addr and
1176  * copied static data to each unit.
1177  *
1178  * If the first chunk ends up with both reserved and dynamic areas, it
1179  * is served by two chunks - one to serve the core static and reserved
1180  * areas and the other for the dynamic area.  They share the same vm
1181  * and page map but uses different area allocation map to stay away
1182  * from each other.  The latter chunk is circulated in the chunk slots
1183  * and available for dynamic allocation like any other chunks.
1184  *
1185  * RETURNS:
1186  * 0 on success, -errno on failure.
1187  */
1188 int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
1189 				  void *base_addr)
1190 {
1191 	static char cpus_buf[4096] __initdata;
1192 	static int smap[PERCPU_DYNAMIC_EARLY_SLOTS] __initdata;
1193 	static int dmap[PERCPU_DYNAMIC_EARLY_SLOTS] __initdata;
1194 	size_t dyn_size = ai->dyn_size;
1195 	size_t size_sum = ai->static_size + ai->reserved_size + dyn_size;
1196 	struct pcpu_chunk *schunk, *dchunk = NULL;
1197 	unsigned long *group_offsets;
1198 	size_t *group_sizes;
1199 	unsigned long *unit_off;
1200 	unsigned int cpu;
1201 	int *unit_map;
1202 	int group, unit, i;
1203 
1204 	cpumask_scnprintf(cpus_buf, sizeof(cpus_buf), cpu_possible_mask);
1205 
1206 #define PCPU_SETUP_BUG_ON(cond)	do {					\
1207 	if (unlikely(cond)) {						\
1208 		pr_emerg("PERCPU: failed to initialize, %s", #cond);	\
1209 		pr_emerg("PERCPU: cpu_possible_mask=%s\n", cpus_buf);	\
1210 		pcpu_dump_alloc_info(KERN_EMERG, ai);			\
1211 		BUG();							\
1212 	}								\
1213 } while (0)
1214 
1215 	/* sanity checks */
1216 	PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
1217 #ifdef CONFIG_SMP
1218 	PCPU_SETUP_BUG_ON(!ai->static_size);
1219 #endif
1220 	PCPU_SETUP_BUG_ON(!base_addr);
1221 	PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
1222 	PCPU_SETUP_BUG_ON(ai->unit_size & ~PAGE_MASK);
1223 	PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
1224 	PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE);
1225 	PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0);
1226 
1227 	/* process group information and build config tables accordingly */
1228 	group_offsets = alloc_bootmem(ai->nr_groups * sizeof(group_offsets[0]));
1229 	group_sizes = alloc_bootmem(ai->nr_groups * sizeof(group_sizes[0]));
1230 	unit_map = alloc_bootmem(nr_cpu_ids * sizeof(unit_map[0]));
1231 	unit_off = alloc_bootmem(nr_cpu_ids * sizeof(unit_off[0]));
1232 
1233 	for (cpu = 0; cpu < nr_cpu_ids; cpu++)
1234 		unit_map[cpu] = UINT_MAX;
1235 	pcpu_first_unit_cpu = NR_CPUS;
1236 
1237 	for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
1238 		const struct pcpu_group_info *gi = &ai->groups[group];
1239 
1240 		group_offsets[group] = gi->base_offset;
1241 		group_sizes[group] = gi->nr_units * ai->unit_size;
1242 
1243 		for (i = 0; i < gi->nr_units; i++) {
1244 			cpu = gi->cpu_map[i];
1245 			if (cpu == NR_CPUS)
1246 				continue;
1247 
1248 			PCPU_SETUP_BUG_ON(cpu > nr_cpu_ids);
1249 			PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
1250 			PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
1251 
1252 			unit_map[cpu] = unit + i;
1253 			unit_off[cpu] = gi->base_offset + i * ai->unit_size;
1254 
1255 			if (pcpu_first_unit_cpu == NR_CPUS)
1256 				pcpu_first_unit_cpu = cpu;
1257 			pcpu_last_unit_cpu = cpu;
1258 		}
1259 	}
1260 	pcpu_nr_units = unit;
1261 
1262 	for_each_possible_cpu(cpu)
1263 		PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
1264 
1265 	/* we're done parsing the input, undefine BUG macro and dump config */
1266 #undef PCPU_SETUP_BUG_ON
1267 	pcpu_dump_alloc_info(KERN_DEBUG, ai);
1268 
1269 	pcpu_nr_groups = ai->nr_groups;
1270 	pcpu_group_offsets = group_offsets;
1271 	pcpu_group_sizes = group_sizes;
1272 	pcpu_unit_map = unit_map;
1273 	pcpu_unit_offsets = unit_off;
1274 
1275 	/* determine basic parameters */
1276 	pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
1277 	pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
1278 	pcpu_atom_size = ai->atom_size;
1279 	pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
1280 		BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
1281 
1282 	/*
1283 	 * Allocate chunk slots.  The additional last slot is for
1284 	 * empty chunks.
1285 	 */
1286 	pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2;
1287 	pcpu_slot = alloc_bootmem(pcpu_nr_slots * sizeof(pcpu_slot[0]));
1288 	for (i = 0; i < pcpu_nr_slots; i++)
1289 		INIT_LIST_HEAD(&pcpu_slot[i]);
1290 
1291 	/*
1292 	 * Initialize static chunk.  If reserved_size is zero, the
1293 	 * static chunk covers static area + dynamic allocation area
1294 	 * in the first chunk.  If reserved_size is not zero, it
1295 	 * covers static area + reserved area (mostly used for module
1296 	 * static percpu allocation).
1297 	 */
1298 	schunk = alloc_bootmem(pcpu_chunk_struct_size);
1299 	INIT_LIST_HEAD(&schunk->list);
1300 	schunk->base_addr = base_addr;
1301 	schunk->map = smap;
1302 	schunk->map_alloc = ARRAY_SIZE(smap);
1303 	schunk->immutable = true;
1304 	bitmap_fill(schunk->populated, pcpu_unit_pages);
1305 
1306 	if (ai->reserved_size) {
1307 		schunk->free_size = ai->reserved_size;
1308 		pcpu_reserved_chunk = schunk;
1309 		pcpu_reserved_chunk_limit = ai->static_size + ai->reserved_size;
1310 	} else {
1311 		schunk->free_size = dyn_size;
1312 		dyn_size = 0;			/* dynamic area covered */
1313 	}
1314 	schunk->contig_hint = schunk->free_size;
1315 
1316 	schunk->map[schunk->map_used++] = -ai->static_size;
1317 	if (schunk->free_size)
1318 		schunk->map[schunk->map_used++] = schunk->free_size;
1319 
1320 	/* init dynamic chunk if necessary */
1321 	if (dyn_size) {
1322 		dchunk = alloc_bootmem(pcpu_chunk_struct_size);
1323 		INIT_LIST_HEAD(&dchunk->list);
1324 		dchunk->base_addr = base_addr;
1325 		dchunk->map = dmap;
1326 		dchunk->map_alloc = ARRAY_SIZE(dmap);
1327 		dchunk->immutable = true;
1328 		bitmap_fill(dchunk->populated, pcpu_unit_pages);
1329 
1330 		dchunk->contig_hint = dchunk->free_size = dyn_size;
1331 		dchunk->map[dchunk->map_used++] = -pcpu_reserved_chunk_limit;
1332 		dchunk->map[dchunk->map_used++] = dchunk->free_size;
1333 	}
1334 
1335 	/* link the first chunk in */
1336 	pcpu_first_chunk = dchunk ?: schunk;
1337 	pcpu_chunk_relocate(pcpu_first_chunk, -1);
1338 
1339 	/* we're done */
1340 	pcpu_base_addr = base_addr;
1341 	return 0;
1342 }
1343 
1344 #ifdef CONFIG_SMP
1345 
1346 const char *pcpu_fc_names[PCPU_FC_NR] __initdata = {
1347 	[PCPU_FC_AUTO]	= "auto",
1348 	[PCPU_FC_EMBED]	= "embed",
1349 	[PCPU_FC_PAGE]	= "page",
1350 };
1351 
1352 enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
1353 
1354 static int __init percpu_alloc_setup(char *str)
1355 {
1356 	if (0)
1357 		/* nada */;
1358 #ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
1359 	else if (!strcmp(str, "embed"))
1360 		pcpu_chosen_fc = PCPU_FC_EMBED;
1361 #endif
1362 #ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
1363 	else if (!strcmp(str, "page"))
1364 		pcpu_chosen_fc = PCPU_FC_PAGE;
1365 #endif
1366 	else
1367 		pr_warning("PERCPU: unknown allocator %s specified\n", str);
1368 
1369 	return 0;
1370 }
1371 early_param("percpu_alloc", percpu_alloc_setup);
1372 
1373 /*
1374  * pcpu_embed_first_chunk() is used by the generic percpu setup.
1375  * Build it if needed by the arch config or the generic setup is going
1376  * to be used.
1377  */
1378 #if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
1379 	!defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
1380 #define BUILD_EMBED_FIRST_CHUNK
1381 #endif
1382 
1383 /* build pcpu_page_first_chunk() iff needed by the arch config */
1384 #if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
1385 #define BUILD_PAGE_FIRST_CHUNK
1386 #endif
1387 
1388 /* pcpu_build_alloc_info() is used by both embed and page first chunk */
1389 #if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK)
1390 /**
1391  * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
1392  * @reserved_size: the size of reserved percpu area in bytes
1393  * @dyn_size: minimum free size for dynamic allocation in bytes
1394  * @atom_size: allocation atom size
1395  * @cpu_distance_fn: callback to determine distance between cpus, optional
1396  *
1397  * This function determines grouping of units, their mappings to cpus
1398  * and other parameters considering needed percpu size, allocation
1399  * atom size and distances between CPUs.
1400  *
1401  * Groups are always mutliples of atom size and CPUs which are of
1402  * LOCAL_DISTANCE both ways are grouped together and share space for
1403  * units in the same group.  The returned configuration is guaranteed
1404  * to have CPUs on different nodes on different groups and >=75% usage
1405  * of allocated virtual address space.
1406  *
1407  * RETURNS:
1408  * On success, pointer to the new allocation_info is returned.  On
1409  * failure, ERR_PTR value is returned.
1410  */
1411 static struct pcpu_alloc_info * __init pcpu_build_alloc_info(
1412 				size_t reserved_size, size_t dyn_size,
1413 				size_t atom_size,
1414 				pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
1415 {
1416 	static int group_map[NR_CPUS] __initdata;
1417 	static int group_cnt[NR_CPUS] __initdata;
1418 	const size_t static_size = __per_cpu_end - __per_cpu_start;
1419 	int nr_groups = 1, nr_units = 0;
1420 	size_t size_sum, min_unit_size, alloc_size;
1421 	int upa, max_upa, uninitialized_var(best_upa);	/* units_per_alloc */
1422 	int last_allocs, group, unit;
1423 	unsigned int cpu, tcpu;
1424 	struct pcpu_alloc_info *ai;
1425 	unsigned int *cpu_map;
1426 
1427 	/* this function may be called multiple times */
1428 	memset(group_map, 0, sizeof(group_map));
1429 	memset(group_cnt, 0, sizeof(group_cnt));
1430 
1431 	/* calculate size_sum and ensure dyn_size is enough for early alloc */
1432 	size_sum = PFN_ALIGN(static_size + reserved_size +
1433 			    max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
1434 	dyn_size = size_sum - static_size - reserved_size;
1435 
1436 	/*
1437 	 * Determine min_unit_size, alloc_size and max_upa such that
1438 	 * alloc_size is multiple of atom_size and is the smallest
1439 	 * which can accomodate 4k aligned segments which are equal to
1440 	 * or larger than min_unit_size.
1441 	 */
1442 	min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
1443 
1444 	alloc_size = roundup(min_unit_size, atom_size);
1445 	upa = alloc_size / min_unit_size;
1446 	while (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
1447 		upa--;
1448 	max_upa = upa;
1449 
1450 	/* group cpus according to their proximity */
1451 	for_each_possible_cpu(cpu) {
1452 		group = 0;
1453 	next_group:
1454 		for_each_possible_cpu(tcpu) {
1455 			if (cpu == tcpu)
1456 				break;
1457 			if (group_map[tcpu] == group && cpu_distance_fn &&
1458 			    (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE ||
1459 			     cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) {
1460 				group++;
1461 				nr_groups = max(nr_groups, group + 1);
1462 				goto next_group;
1463 			}
1464 		}
1465 		group_map[cpu] = group;
1466 		group_cnt[group]++;
1467 	}
1468 
1469 	/*
1470 	 * Expand unit size until address space usage goes over 75%
1471 	 * and then as much as possible without using more address
1472 	 * space.
1473 	 */
1474 	last_allocs = INT_MAX;
1475 	for (upa = max_upa; upa; upa--) {
1476 		int allocs = 0, wasted = 0;
1477 
1478 		if (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
1479 			continue;
1480 
1481 		for (group = 0; group < nr_groups; group++) {
1482 			int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
1483 			allocs += this_allocs;
1484 			wasted += this_allocs * upa - group_cnt[group];
1485 		}
1486 
1487 		/*
1488 		 * Don't accept if wastage is over 1/3.  The
1489 		 * greater-than comparison ensures upa==1 always
1490 		 * passes the following check.
1491 		 */
1492 		if (wasted > num_possible_cpus() / 3)
1493 			continue;
1494 
1495 		/* and then don't consume more memory */
1496 		if (allocs > last_allocs)
1497 			break;
1498 		last_allocs = allocs;
1499 		best_upa = upa;
1500 	}
1501 	upa = best_upa;
1502 
1503 	/* allocate and fill alloc_info */
1504 	for (group = 0; group < nr_groups; group++)
1505 		nr_units += roundup(group_cnt[group], upa);
1506 
1507 	ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
1508 	if (!ai)
1509 		return ERR_PTR(-ENOMEM);
1510 	cpu_map = ai->groups[0].cpu_map;
1511 
1512 	for (group = 0; group < nr_groups; group++) {
1513 		ai->groups[group].cpu_map = cpu_map;
1514 		cpu_map += roundup(group_cnt[group], upa);
1515 	}
1516 
1517 	ai->static_size = static_size;
1518 	ai->reserved_size = reserved_size;
1519 	ai->dyn_size = dyn_size;
1520 	ai->unit_size = alloc_size / upa;
1521 	ai->atom_size = atom_size;
1522 	ai->alloc_size = alloc_size;
1523 
1524 	for (group = 0, unit = 0; group_cnt[group]; group++) {
1525 		struct pcpu_group_info *gi = &ai->groups[group];
1526 
1527 		/*
1528 		 * Initialize base_offset as if all groups are located
1529 		 * back-to-back.  The caller should update this to
1530 		 * reflect actual allocation.
1531 		 */
1532 		gi->base_offset = unit * ai->unit_size;
1533 
1534 		for_each_possible_cpu(cpu)
1535 			if (group_map[cpu] == group)
1536 				gi->cpu_map[gi->nr_units++] = cpu;
1537 		gi->nr_units = roundup(gi->nr_units, upa);
1538 		unit += gi->nr_units;
1539 	}
1540 	BUG_ON(unit != nr_units);
1541 
1542 	return ai;
1543 }
1544 #endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */
1545 
1546 #if defined(BUILD_EMBED_FIRST_CHUNK)
1547 /**
1548  * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
1549  * @reserved_size: the size of reserved percpu area in bytes
1550  * @dyn_size: minimum free size for dynamic allocation in bytes
1551  * @atom_size: allocation atom size
1552  * @cpu_distance_fn: callback to determine distance between cpus, optional
1553  * @alloc_fn: function to allocate percpu page
1554  * @free_fn: funtion to free percpu page
1555  *
1556  * This is a helper to ease setting up embedded first percpu chunk and
1557  * can be called where pcpu_setup_first_chunk() is expected.
1558  *
1559  * If this function is used to setup the first chunk, it is allocated
1560  * by calling @alloc_fn and used as-is without being mapped into
1561  * vmalloc area.  Allocations are always whole multiples of @atom_size
1562  * aligned to @atom_size.
1563  *
1564  * This enables the first chunk to piggy back on the linear physical
1565  * mapping which often uses larger page size.  Please note that this
1566  * can result in very sparse cpu->unit mapping on NUMA machines thus
1567  * requiring large vmalloc address space.  Don't use this allocator if
1568  * vmalloc space is not orders of magnitude larger than distances
1569  * between node memory addresses (ie. 32bit NUMA machines).
1570  *
1571  * @dyn_size specifies the minimum dynamic area size.
1572  *
1573  * If the needed size is smaller than the minimum or specified unit
1574  * size, the leftover is returned using @free_fn.
1575  *
1576  * RETURNS:
1577  * 0 on success, -errno on failure.
1578  */
1579 int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
1580 				  size_t atom_size,
1581 				  pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
1582 				  pcpu_fc_alloc_fn_t alloc_fn,
1583 				  pcpu_fc_free_fn_t free_fn)
1584 {
1585 	void *base = (void *)ULONG_MAX;
1586 	void **areas = NULL;
1587 	struct pcpu_alloc_info *ai;
1588 	size_t size_sum, areas_size, max_distance;
1589 	int group, i, rc;
1590 
1591 	ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
1592 				   cpu_distance_fn);
1593 	if (IS_ERR(ai))
1594 		return PTR_ERR(ai);
1595 
1596 	size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
1597 	areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *));
1598 
1599 	areas = alloc_bootmem_nopanic(areas_size);
1600 	if (!areas) {
1601 		rc = -ENOMEM;
1602 		goto out_free;
1603 	}
1604 
1605 	/* allocate, copy and determine base address */
1606 	for (group = 0; group < ai->nr_groups; group++) {
1607 		struct pcpu_group_info *gi = &ai->groups[group];
1608 		unsigned int cpu = NR_CPUS;
1609 		void *ptr;
1610 
1611 		for (i = 0; i < gi->nr_units && cpu == NR_CPUS; i++)
1612 			cpu = gi->cpu_map[i];
1613 		BUG_ON(cpu == NR_CPUS);
1614 
1615 		/* allocate space for the whole group */
1616 		ptr = alloc_fn(cpu, gi->nr_units * ai->unit_size, atom_size);
1617 		if (!ptr) {
1618 			rc = -ENOMEM;
1619 			goto out_free_areas;
1620 		}
1621 		areas[group] = ptr;
1622 
1623 		base = min(ptr, base);
1624 
1625 		for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) {
1626 			if (gi->cpu_map[i] == NR_CPUS) {
1627 				/* unused unit, free whole */
1628 				free_fn(ptr, ai->unit_size);
1629 				continue;
1630 			}
1631 			/* copy and return the unused part */
1632 			memcpy(ptr, __per_cpu_load, ai->static_size);
1633 			free_fn(ptr + size_sum, ai->unit_size - size_sum);
1634 		}
1635 	}
1636 
1637 	/* base address is now known, determine group base offsets */
1638 	max_distance = 0;
1639 	for (group = 0; group < ai->nr_groups; group++) {
1640 		ai->groups[group].base_offset = areas[group] - base;
1641 		max_distance = max_t(size_t, max_distance,
1642 				     ai->groups[group].base_offset);
1643 	}
1644 	max_distance += ai->unit_size;
1645 
1646 	/* warn if maximum distance is further than 75% of vmalloc space */
1647 	if (max_distance > (VMALLOC_END - VMALLOC_START) * 3 / 4) {
1648 		pr_warning("PERCPU: max_distance=0x%zx too large for vmalloc "
1649 			   "space 0x%lx\n",
1650 			   max_distance, VMALLOC_END - VMALLOC_START);
1651 #ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
1652 		/* and fail if we have fallback */
1653 		rc = -EINVAL;
1654 		goto out_free;
1655 #endif
1656 	}
1657 
1658 	pr_info("PERCPU: Embedded %zu pages/cpu @%p s%zu r%zu d%zu u%zu\n",
1659 		PFN_DOWN(size_sum), base, ai->static_size, ai->reserved_size,
1660 		ai->dyn_size, ai->unit_size);
1661 
1662 	rc = pcpu_setup_first_chunk(ai, base);
1663 	goto out_free;
1664 
1665 out_free_areas:
1666 	for (group = 0; group < ai->nr_groups; group++)
1667 		free_fn(areas[group],
1668 			ai->groups[group].nr_units * ai->unit_size);
1669 out_free:
1670 	pcpu_free_alloc_info(ai);
1671 	if (areas)
1672 		free_bootmem(__pa(areas), areas_size);
1673 	return rc;
1674 }
1675 #endif /* BUILD_EMBED_FIRST_CHUNK */
1676 
1677 #ifdef BUILD_PAGE_FIRST_CHUNK
1678 /**
1679  * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
1680  * @reserved_size: the size of reserved percpu area in bytes
1681  * @alloc_fn: function to allocate percpu page, always called with PAGE_SIZE
1682  * @free_fn: funtion to free percpu page, always called with PAGE_SIZE
1683  * @populate_pte_fn: function to populate pte
1684  *
1685  * This is a helper to ease setting up page-remapped first percpu
1686  * chunk and can be called where pcpu_setup_first_chunk() is expected.
1687  *
1688  * This is the basic allocator.  Static percpu area is allocated
1689  * page-by-page into vmalloc area.
1690  *
1691  * RETURNS:
1692  * 0 on success, -errno on failure.
1693  */
1694 int __init pcpu_page_first_chunk(size_t reserved_size,
1695 				 pcpu_fc_alloc_fn_t alloc_fn,
1696 				 pcpu_fc_free_fn_t free_fn,
1697 				 pcpu_fc_populate_pte_fn_t populate_pte_fn)
1698 {
1699 	static struct vm_struct vm;
1700 	struct pcpu_alloc_info *ai;
1701 	char psize_str[16];
1702 	int unit_pages;
1703 	size_t pages_size;
1704 	struct page **pages;
1705 	int unit, i, j, rc;
1706 
1707 	snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);
1708 
1709 	ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL);
1710 	if (IS_ERR(ai))
1711 		return PTR_ERR(ai);
1712 	BUG_ON(ai->nr_groups != 1);
1713 	BUG_ON(ai->groups[0].nr_units != num_possible_cpus());
1714 
1715 	unit_pages = ai->unit_size >> PAGE_SHIFT;
1716 
1717 	/* unaligned allocations can't be freed, round up to page size */
1718 	pages_size = PFN_ALIGN(unit_pages * num_possible_cpus() *
1719 			       sizeof(pages[0]));
1720 	pages = alloc_bootmem(pages_size);
1721 
1722 	/* allocate pages */
1723 	j = 0;
1724 	for (unit = 0; unit < num_possible_cpus(); unit++)
1725 		for (i = 0; i < unit_pages; i++) {
1726 			unsigned int cpu = ai->groups[0].cpu_map[unit];
1727 			void *ptr;
1728 
1729 			ptr = alloc_fn(cpu, PAGE_SIZE, PAGE_SIZE);
1730 			if (!ptr) {
1731 				pr_warning("PERCPU: failed to allocate %s page "
1732 					   "for cpu%u\n", psize_str, cpu);
1733 				goto enomem;
1734 			}
1735 			pages[j++] = virt_to_page(ptr);
1736 		}
1737 
1738 	/* allocate vm area, map the pages and copy static data */
1739 	vm.flags = VM_ALLOC;
1740 	vm.size = num_possible_cpus() * ai->unit_size;
1741 	vm_area_register_early(&vm, PAGE_SIZE);
1742 
1743 	for (unit = 0; unit < num_possible_cpus(); unit++) {
1744 		unsigned long unit_addr =
1745 			(unsigned long)vm.addr + unit * ai->unit_size;
1746 
1747 		for (i = 0; i < unit_pages; i++)
1748 			populate_pte_fn(unit_addr + (i << PAGE_SHIFT));
1749 
1750 		/* pte already populated, the following shouldn't fail */
1751 		rc = __pcpu_map_pages(unit_addr, &pages[unit * unit_pages],
1752 				      unit_pages);
1753 		if (rc < 0)
1754 			panic("failed to map percpu area, err=%d\n", rc);
1755 
1756 		/*
1757 		 * FIXME: Archs with virtual cache should flush local
1758 		 * cache for the linear mapping here - something
1759 		 * equivalent to flush_cache_vmap() on the local cpu.
1760 		 * flush_cache_vmap() can't be used as most supporting
1761 		 * data structures are not set up yet.
1762 		 */
1763 
1764 		/* copy static data */
1765 		memcpy((void *)unit_addr, __per_cpu_load, ai->static_size);
1766 	}
1767 
1768 	/* we're ready, commit */
1769 	pr_info("PERCPU: %d %s pages/cpu @%p s%zu r%zu d%zu\n",
1770 		unit_pages, psize_str, vm.addr, ai->static_size,
1771 		ai->reserved_size, ai->dyn_size);
1772 
1773 	rc = pcpu_setup_first_chunk(ai, vm.addr);
1774 	goto out_free_ar;
1775 
1776 enomem:
1777 	while (--j >= 0)
1778 		free_fn(page_address(pages[j]), PAGE_SIZE);
1779 	rc = -ENOMEM;
1780 out_free_ar:
1781 	free_bootmem(__pa(pages), pages_size);
1782 	pcpu_free_alloc_info(ai);
1783 	return rc;
1784 }
1785 #endif /* BUILD_PAGE_FIRST_CHUNK */
1786 
1787 #ifndef	CONFIG_HAVE_SETUP_PER_CPU_AREA
1788 /*
1789  * Generic SMP percpu area setup.
1790  *
1791  * The embedding helper is used because its behavior closely resembles
1792  * the original non-dynamic generic percpu area setup.  This is
1793  * important because many archs have addressing restrictions and might
1794  * fail if the percpu area is located far away from the previous
1795  * location.  As an added bonus, in non-NUMA cases, embedding is
1796  * generally a good idea TLB-wise because percpu area can piggy back
1797  * on the physical linear memory mapping which uses large page
1798  * mappings on applicable archs.
1799  */
1800 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
1801 EXPORT_SYMBOL(__per_cpu_offset);
1802 
1803 static void * __init pcpu_dfl_fc_alloc(unsigned int cpu, size_t size,
1804 				       size_t align)
1805 {
1806 	return __alloc_bootmem_nopanic(size, align, __pa(MAX_DMA_ADDRESS));
1807 }
1808 
1809 static void __init pcpu_dfl_fc_free(void *ptr, size_t size)
1810 {
1811 	free_bootmem(__pa(ptr), size);
1812 }
1813 
1814 void __init setup_per_cpu_areas(void)
1815 {
1816 	unsigned long delta;
1817 	unsigned int cpu;
1818 	int rc;
1819 
1820 	/*
1821 	 * Always reserve area for module percpu variables.  That's
1822 	 * what the legacy allocator did.
1823 	 */
1824 	rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
1825 				    PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL,
1826 				    pcpu_dfl_fc_alloc, pcpu_dfl_fc_free);
1827 	if (rc < 0)
1828 		panic("Failed to initialize percpu areas.");
1829 
1830 	delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
1831 	for_each_possible_cpu(cpu)
1832 		__per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
1833 }
1834 #endif	/* CONFIG_HAVE_SETUP_PER_CPU_AREA */
1835 
1836 #else	/* CONFIG_SMP */
1837 
1838 /*
1839  * UP percpu area setup.
1840  *
1841  * UP always uses km-based percpu allocator with identity mapping.
1842  * Static percpu variables are indistinguishable from the usual static
1843  * variables and don't require any special preparation.
1844  */
1845 void __init setup_per_cpu_areas(void)
1846 {
1847 	const size_t unit_size =
1848 		roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
1849 					 PERCPU_DYNAMIC_RESERVE));
1850 	struct pcpu_alloc_info *ai;
1851 	void *fc;
1852 
1853 	ai = pcpu_alloc_alloc_info(1, 1);
1854 	fc = __alloc_bootmem(unit_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
1855 	if (!ai || !fc)
1856 		panic("Failed to allocate memory for percpu areas.");
1857 
1858 	ai->dyn_size = unit_size;
1859 	ai->unit_size = unit_size;
1860 	ai->atom_size = unit_size;
1861 	ai->alloc_size = unit_size;
1862 	ai->groups[0].nr_units = 1;
1863 	ai->groups[0].cpu_map[0] = 0;
1864 
1865 	if (pcpu_setup_first_chunk(ai, fc) < 0)
1866 		panic("Failed to initialize percpu areas.");
1867 }
1868 
1869 #endif	/* CONFIG_SMP */
1870 
1871 /*
1872  * First and reserved chunks are initialized with temporary allocation
1873  * map in initdata so that they can be used before slab is online.
1874  * This function is called after slab is brought up and replaces those
1875  * with properly allocated maps.
1876  */
1877 void __init percpu_init_late(void)
1878 {
1879 	struct pcpu_chunk *target_chunks[] =
1880 		{ pcpu_first_chunk, pcpu_reserved_chunk, NULL };
1881 	struct pcpu_chunk *chunk;
1882 	unsigned long flags;
1883 	int i;
1884 
1885 	for (i = 0; (chunk = target_chunks[i]); i++) {
1886 		int *map;
1887 		const size_t size = PERCPU_DYNAMIC_EARLY_SLOTS * sizeof(map[0]);
1888 
1889 		BUILD_BUG_ON(size > PAGE_SIZE);
1890 
1891 		map = pcpu_mem_alloc(size);
1892 		BUG_ON(!map);
1893 
1894 		spin_lock_irqsave(&pcpu_lock, flags);
1895 		memcpy(map, chunk->map, size);
1896 		chunk->map = map;
1897 		spin_unlock_irqrestore(&pcpu_lock, flags);
1898 	}
1899 }
1900