linux/mm/percpu.c
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   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
  99struct 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
 112static int pcpu_unit_pages __read_mostly;
 113static int pcpu_unit_size __read_mostly;
 114static int pcpu_nr_units __read_mostly;
 115static int pcpu_atom_size __read_mostly;
 116static int pcpu_nr_slots __read_mostly;
 117static size_t pcpu_chunk_struct_size __read_mostly;
 118
 119/* cpus with the lowest and highest unit addresses */
 120static unsigned int pcpu_low_unit_cpu __read_mostly;
 121static unsigned int pcpu_high_unit_cpu __read_mostly;
 122
 123/* the address of the first chunk which starts with the kernel static area */
 124void *pcpu_base_addr __read_mostly;
 125EXPORT_SYMBOL_GPL(pcpu_base_addr);
 126
 127static const int *pcpu_unit_map __read_mostly;          /* cpu -> unit */
 128const unsigned long *pcpu_unit_offsets __read_mostly;   /* cpu -> unit offset */
 129
 130/* group information, used for vm allocation */
 131static int pcpu_nr_groups __read_mostly;
 132static const unsigned long *pcpu_group_offsets __read_mostly;
 133static 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 */
 140static 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 */
 149static struct pcpu_chunk *pcpu_reserved_chunk;
 150static 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 */
 176static DEFINE_MUTEX(pcpu_alloc_mutex);  /* protects whole alloc and reclaim */
 177static DEFINE_SPINLOCK(pcpu_lock);      /* protects index data structures */
 178
 179static struct list_head *pcpu_slot __read_mostly; /* chunk list slots */
 180
 181/* reclaim work to release fully free chunks, scheduled from free path */
 182static void pcpu_reclaim(struct work_struct *work);
 183static DECLARE_WORK(pcpu_reclaim_work, pcpu_reclaim);
 184
 185static 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
 192static 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
 200static 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
 206static 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
 213static 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 */
 222static 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 */
 228static struct pcpu_chunk *pcpu_get_page_chunk(struct page *page)
 229{
 230        return (struct pcpu_chunk *)page->index;
 231}
 232
 233static 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
 238static 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
 245static 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
 252static 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 */
 289static 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 */
 307static 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 */
 328static 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 * accommodate 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 */
 354static 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 */
 381static 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
 406out_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 accommodate the split.
 435 *
 436 * CONTEXT:
 437 * pcpu_lock.
 438 */
 439static 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 */
 480static 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 */
 569static 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
 603static 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
 627static 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 */
 650static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size);
 651static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size);
 652static struct pcpu_chunk *pcpu_create_chunk(void);
 653static void pcpu_destroy_chunk(struct pcpu_chunk *chunk);
 654static struct page *pcpu_addr_to_page(void *addr);
 655static 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 */
 670static 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 */
 705static 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
 748restart:
 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
 790area_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
 806fail_unlock:
 807        spin_unlock_irqrestore(&pcpu_lock, flags);
 808fail_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 */
 834void __percpu *__alloc_percpu(size_t size, size_t align)
 835{
 836        return pcpu_alloc(size, align, false);
 837}
 838EXPORT_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 */
 856void __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 */
 870static 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 */
 908void 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}
 940EXPORT_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 */
 953bool 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 */
 983phys_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_low, first_high;
 988        unsigned int cpu;
 989
 990        /*
 991         * The following test on unit_low/high isn't strictly
 992         * necessary but will speed up lookups of addresses which
 993         * aren't in the first chunk.
 994         */
 995        first_low = pcpu_chunk_addr(pcpu_first_chunk, pcpu_low_unit_cpu, 0);
 996        first_high = pcpu_chunk_addr(pcpu_first_chunk, pcpu_high_unit_cpu,
 997                                     pcpu_unit_pages);
 998        if ((unsigned long)addr >= first_low &&
 999            (unsigned long)addr < first_high) {
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 (!is_vmalloc_addr(addr))
1012                        return __pa(addr);
1013                else
1014                        return page_to_phys(vmalloc_to_page(addr));
1015        } else
1016                return page_to_phys(pcpu_addr_to_page(addr));
1017}
1018
1019/**
1020 * pcpu_alloc_alloc_info - allocate percpu allocation info
1021 * @nr_groups: the number of groups
1022 * @nr_units: the number of units
1023 *
1024 * Allocate ai which is large enough for @nr_groups groups containing
1025 * @nr_units units.  The returned ai's groups[0].cpu_map points to the
1026 * cpu_map array which is long enough for @nr_units and filled with
1027 * NR_CPUS.  It's the caller's responsibility to initialize cpu_map
1028 * pointer of other groups.
1029 *
1030 * RETURNS:
1031 * Pointer to the allocated pcpu_alloc_info on success, NULL on
1032 * failure.
1033 */
1034struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
1035                                                      int nr_units)
1036{
1037        struct pcpu_alloc_info *ai;
1038        size_t base_size, ai_size;
1039        void *ptr;
1040        int unit;
1041
1042        base_size = ALIGN(sizeof(*ai) + nr_groups * sizeof(ai->groups[0]),
1043                          __alignof__(ai->groups[0].cpu_map[0]));
1044        ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]);
1045
1046        ptr = alloc_bootmem_nopanic(PFN_ALIGN(ai_size));
1047        if (!ptr)
1048                return NULL;
1049        ai = ptr;
1050        ptr += base_size;
1051
1052        ai->groups[0].cpu_map = ptr;
1053
1054        for (unit = 0; unit < nr_units; unit++)
1055                ai->groups[0].cpu_map[unit] = NR_CPUS;
1056
1057        ai->nr_groups = nr_groups;
1058        ai->__ai_size = PFN_ALIGN(ai_size);
1059
1060        return ai;
1061}
1062
1063/**
1064 * pcpu_free_alloc_info - free percpu allocation info
1065 * @ai: pcpu_alloc_info to free
1066 *
1067 * Free @ai which was allocated by pcpu_alloc_alloc_info().
1068 */
1069void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
1070{
1071        free_bootmem(__pa(ai), ai->__ai_size);
1072}
1073
1074/**
1075 * pcpu_dump_alloc_info - print out information about pcpu_alloc_info
1076 * @lvl: loglevel
1077 * @ai: allocation info to dump
1078 *
1079 * Print out information about @ai using loglevel @lvl.
1080 */
1081static void pcpu_dump_alloc_info(const char *lvl,
1082                                 const struct pcpu_alloc_info *ai)
1083{
1084        int group_width = 1, cpu_width = 1, width;
1085        char empty_str[] = "--------";
1086        int alloc = 0, alloc_end = 0;
1087        int group, v;
1088        int upa, apl;   /* units per alloc, allocs per line */
1089
1090        v = ai->nr_groups;
1091        while (v /= 10)
1092                group_width++;
1093
1094        v = num_possible_cpus();
1095        while (v /= 10)
1096                cpu_width++;
1097        empty_str[min_t(int, cpu_width, sizeof(empty_str) - 1)] = '\0';
1098
1099        upa = ai->alloc_size / ai->unit_size;
1100        width = upa * (cpu_width + 1) + group_width + 3;
1101        apl = rounddown_pow_of_two(max(60 / width, 1));
1102
1103        printk("%spcpu-alloc: s%zu r%zu d%zu u%zu alloc=%zu*%zu",
1104               lvl, ai->static_size, ai->reserved_size, ai->dyn_size,
1105               ai->unit_size, ai->alloc_size / ai->atom_size, ai->atom_size);
1106
1107        for (group = 0; group < ai->nr_groups; group++) {
1108                const struct pcpu_group_info *gi = &ai->groups[group];
1109                int unit = 0, unit_end = 0;
1110
1111                BUG_ON(gi->nr_units % upa);
1112                for (alloc_end += gi->nr_units / upa;
1113                     alloc < alloc_end; alloc++) {
1114                        if (!(alloc % apl)) {
1115                                printk("\n");
1116                                printk("%spcpu-alloc: ", lvl);
1117                        }
1118                        printk("[%0*d] ", group_width, group);
1119
1120                        for (unit_end += upa; unit < unit_end; unit++)
1121                                if (gi->cpu_map[unit] != NR_CPUS)
1122                                        printk("%0*d ", cpu_width,
1123                                               gi->cpu_map[unit]);
1124                                else
1125                                        printk("%s ", empty_str);
1126                }
1127        }
1128        printk("\n");
1129}
1130
1131/**
1132 * pcpu_setup_first_chunk - initialize the first percpu chunk
1133 * @ai: pcpu_alloc_info describing how to percpu area is shaped
1134 * @base_addr: mapped address
1135 *
1136 * Initialize the first percpu chunk which contains the kernel static
1137 * perpcu area.  This function is to be called from arch percpu area
1138 * setup path.
1139 *
1140 * @ai contains all information necessary to initialize the first
1141 * chunk and prime the dynamic percpu allocator.
1142 *
1143 * @ai->static_size is the size of static percpu area.
1144 *
1145 * @ai->reserved_size, if non-zero, specifies the amount of bytes to
1146 * reserve after the static area in the first chunk.  This reserves
1147 * the first chunk such that it's available only through reserved
1148 * percpu allocation.  This is primarily used to serve module percpu
1149 * static areas on architectures where the addressing model has
1150 * limited offset range for symbol relocations to guarantee module
1151 * percpu symbols fall inside the relocatable range.
1152 *
1153 * @ai->dyn_size determines the number of bytes available for dynamic
1154 * allocation in the first chunk.  The area between @ai->static_size +
1155 * @ai->reserved_size + @ai->dyn_size and @ai->unit_size is unused.
1156 *
1157 * @ai->unit_size specifies unit size and must be aligned to PAGE_SIZE
1158 * and equal to or larger than @ai->static_size + @ai->reserved_size +
1159 * @ai->dyn_size.
1160 *
1161 * @ai->atom_size is the allocation atom size and used as alignment
1162 * for vm areas.
1163 *
1164 * @ai->alloc_size is the allocation size and always multiple of
1165 * @ai->atom_size.  This is larger than @ai->atom_size if
1166 * @ai->unit_size is larger than @ai->atom_size.
1167 *
1168 * @ai->nr_groups and @ai->groups describe virtual memory layout of
1169 * percpu areas.  Units which should be colocated are put into the
1170 * same group.  Dynamic VM areas will be allocated according to these
1171 * groupings.  If @ai->nr_groups is zero, a single group containing
1172 * all units is assumed.
1173 *
1174 * The caller should have mapped the first chunk at @base_addr and
1175 * copied static data to each unit.
1176 *
1177 * If the first chunk ends up with both reserved and dynamic areas, it
1178 * is served by two chunks - one to serve the core static and reserved
1179 * areas and the other for the dynamic area.  They share the same vm
1180 * and page map but uses different area allocation map to stay away
1181 * from each other.  The latter chunk is circulated in the chunk slots
1182 * and available for dynamic allocation like any other chunks.
1183 *
1184 * RETURNS:
1185 * 0 on success, -errno on failure.
1186 */
1187int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
1188                                  void *base_addr)
1189{
1190        static char cpus_buf[4096] __initdata;
1191        static int smap[PERCPU_DYNAMIC_EARLY_SLOTS] __initdata;
1192        static int dmap[PERCPU_DYNAMIC_EARLY_SLOTS] __initdata;
1193        size_t dyn_size = ai->dyn_size;
1194        size_t size_sum = ai->static_size + ai->reserved_size + dyn_size;
1195        struct pcpu_chunk *schunk, *dchunk = NULL;
1196        unsigned long *group_offsets;
1197        size_t *group_sizes;
1198        unsigned long *unit_off;
1199        unsigned int cpu;
1200        int *unit_map;
1201        int group, unit, i;
1202
1203        cpumask_scnprintf(cpus_buf, sizeof(cpus_buf), cpu_possible_mask);
1204
1205#define PCPU_SETUP_BUG_ON(cond) do {                                    \
1206        if (unlikely(cond)) {                                           \
1207                pr_emerg("PERCPU: failed to initialize, %s", #cond);    \
1208                pr_emerg("PERCPU: cpu_possible_mask=%s\n", cpus_buf);   \
1209                pcpu_dump_alloc_info(KERN_EMERG, ai);                   \
1210                BUG();                                                  \
1211        }                                                               \
1212} while (0)
1213
1214        /* sanity checks */
1215        PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
1216#ifdef CONFIG_SMP
1217        PCPU_SETUP_BUG_ON(!ai->static_size);
1218        PCPU_SETUP_BUG_ON((unsigned long)__per_cpu_start & ~PAGE_MASK);
1219#endif
1220        PCPU_SETUP_BUG_ON(!base_addr);
1221        PCPU_SETUP_BUG_ON((unsigned long)base_addr & ~PAGE_MASK);
1222        PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
1223        PCPU_SETUP_BUG_ON(ai->unit_size & ~PAGE_MASK);
1224        PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
1225        PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE);
1226        PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0);
1227
1228        /* process group information and build config tables accordingly */
1229        group_offsets = alloc_bootmem(ai->nr_groups * sizeof(group_offsets[0]));
1230        group_sizes = alloc_bootmem(ai->nr_groups * sizeof(group_sizes[0]));
1231        unit_map = alloc_bootmem(nr_cpu_ids * sizeof(unit_map[0]));
1232        unit_off = alloc_bootmem(nr_cpu_ids * sizeof(unit_off[0]));
1233
1234        for (cpu = 0; cpu < nr_cpu_ids; cpu++)
1235                unit_map[cpu] = UINT_MAX;
1236
1237        pcpu_low_unit_cpu = NR_CPUS;
1238        pcpu_high_unit_cpu = NR_CPUS;
1239
1240        for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
1241                const struct pcpu_group_info *gi = &ai->groups[group];
1242
1243                group_offsets[group] = gi->base_offset;
1244                group_sizes[group] = gi->nr_units * ai->unit_size;
1245
1246                for (i = 0; i < gi->nr_units; i++) {
1247                        cpu = gi->cpu_map[i];
1248                        if (cpu == NR_CPUS)
1249                                continue;
1250
1251                        PCPU_SETUP_BUG_ON(cpu > nr_cpu_ids);
1252                        PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
1253                        PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
1254
1255                        unit_map[cpu] = unit + i;
1256                        unit_off[cpu] = gi->base_offset + i * ai->unit_size;
1257
1258                        /* determine low/high unit_cpu */
1259                        if (pcpu_low_unit_cpu == NR_CPUS ||
1260                            unit_off[cpu] < unit_off[pcpu_low_unit_cpu])
1261                                pcpu_low_unit_cpu = cpu;
1262                        if (pcpu_high_unit_cpu == NR_CPUS ||
1263                            unit_off[cpu] > unit_off[pcpu_high_unit_cpu])
1264                                pcpu_high_unit_cpu = cpu;
1265                }
1266        }
1267        pcpu_nr_units = unit;
1268
1269        for_each_possible_cpu(cpu)
1270                PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
1271
1272        /* we're done parsing the input, undefine BUG macro and dump config */
1273#undef PCPU_SETUP_BUG_ON
1274        pcpu_dump_alloc_info(KERN_DEBUG, ai);
1275
1276        pcpu_nr_groups = ai->nr_groups;
1277        pcpu_group_offsets = group_offsets;
1278        pcpu_group_sizes = group_sizes;
1279        pcpu_unit_map = unit_map;
1280        pcpu_unit_offsets = unit_off;
1281
1282        /* determine basic parameters */
1283        pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
1284        pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
1285        pcpu_atom_size = ai->atom_size;
1286        pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
1287                BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
1288
1289        /*
1290         * Allocate chunk slots.  The additional last slot is for
1291         * empty chunks.
1292         */
1293        pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2;
1294        pcpu_slot = alloc_bootmem(pcpu_nr_slots * sizeof(pcpu_slot[0]));
1295        for (i = 0; i < pcpu_nr_slots; i++)
1296                INIT_LIST_HEAD(&pcpu_slot[i]);
1297
1298        /*
1299         * Initialize static chunk.  If reserved_size is zero, the
1300         * static chunk covers static area + dynamic allocation area
1301         * in the first chunk.  If reserved_size is not zero, it
1302         * covers static area + reserved area (mostly used for module
1303         * static percpu allocation).
1304         */
1305        schunk = alloc_bootmem(pcpu_chunk_struct_size);
1306        INIT_LIST_HEAD(&schunk->list);
1307        schunk->base_addr = base_addr;
1308        schunk->map = smap;
1309        schunk->map_alloc = ARRAY_SIZE(smap);
1310        schunk->immutable = true;
1311        bitmap_fill(schunk->populated, pcpu_unit_pages);
1312
1313        if (ai->reserved_size) {
1314                schunk->free_size = ai->reserved_size;
1315                pcpu_reserved_chunk = schunk;
1316                pcpu_reserved_chunk_limit = ai->static_size + ai->reserved_size;
1317        } else {
1318                schunk->free_size = dyn_size;
1319                dyn_size = 0;                   /* dynamic area covered */
1320        }
1321        schunk->contig_hint = schunk->free_size;
1322
1323        schunk->map[schunk->map_used++] = -ai->static_size;
1324        if (schunk->free_size)
1325                schunk->map[schunk->map_used++] = schunk->free_size;
1326
1327        /* init dynamic chunk if necessary */
1328        if (dyn_size) {
1329                dchunk = alloc_bootmem(pcpu_chunk_struct_size);
1330                INIT_LIST_HEAD(&dchunk->list);
1331                dchunk->base_addr = base_addr;
1332                dchunk->map = dmap;
1333                dchunk->map_alloc = ARRAY_SIZE(dmap);
1334                dchunk->immutable = true;
1335                bitmap_fill(dchunk->populated, pcpu_unit_pages);
1336
1337                dchunk->contig_hint = dchunk->free_size = dyn_size;
1338                dchunk->map[dchunk->map_used++] = -pcpu_reserved_chunk_limit;
1339                dchunk->map[dchunk->map_used++] = dchunk->free_size;
1340        }
1341
1342        /* link the first chunk in */
1343        pcpu_first_chunk = dchunk ?: schunk;
1344        pcpu_chunk_relocate(pcpu_first_chunk, -1);
1345
1346        /* we're done */
1347        pcpu_base_addr = base_addr;
1348        return 0;
1349}
1350
1351#ifdef CONFIG_SMP
1352
1353const char *pcpu_fc_names[PCPU_FC_NR] __initdata = {
1354        [PCPU_FC_AUTO]  = "auto",
1355        [PCPU_FC_EMBED] = "embed",
1356        [PCPU_FC_PAGE]  = "page",
1357};
1358
1359enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
1360
1361static int __init percpu_alloc_setup(char *str)
1362{
1363        if (0)
1364                /* nada */;
1365#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
1366        else if (!strcmp(str, "embed"))
1367                pcpu_chosen_fc = PCPU_FC_EMBED;
1368#endif
1369#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
1370        else if (!strcmp(str, "page"))
1371                pcpu_chosen_fc = PCPU_FC_PAGE;
1372#endif
1373        else
1374                pr_warning("PERCPU: unknown allocator %s specified\n", str);
1375
1376        return 0;
1377}
1378early_param("percpu_alloc", percpu_alloc_setup);
1379
1380/*
1381 * pcpu_embed_first_chunk() is used by the generic percpu setup.
1382 * Build it if needed by the arch config or the generic setup is going
1383 * to be used.
1384 */
1385#if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
1386        !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
1387#define BUILD_EMBED_FIRST_CHUNK
1388#endif
1389
1390/* build pcpu_page_first_chunk() iff needed by the arch config */
1391#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
1392#define BUILD_PAGE_FIRST_CHUNK
1393#endif
1394
1395/* pcpu_build_alloc_info() is used by both embed and page first chunk */
1396#if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK)
1397/**
1398 * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
1399 * @reserved_size: the size of reserved percpu area in bytes
1400 * @dyn_size: minimum free size for dynamic allocation in bytes
1401 * @atom_size: allocation atom size
1402 * @cpu_distance_fn: callback to determine distance between cpus, optional
1403 *
1404 * This function determines grouping of units, their mappings to cpus
1405 * and other parameters considering needed percpu size, allocation
1406 * atom size and distances between CPUs.
1407 *
1408 * Groups are always mutliples of atom size and CPUs which are of
1409 * LOCAL_DISTANCE both ways are grouped together and share space for
1410 * units in the same group.  The returned configuration is guaranteed
1411 * to have CPUs on different nodes on different groups and >=75% usage
1412 * of allocated virtual address space.
1413 *
1414 * RETURNS:
1415 * On success, pointer to the new allocation_info is returned.  On
1416 * failure, ERR_PTR value is returned.
1417 */
1418static struct pcpu_alloc_info * __init pcpu_build_alloc_info(
1419                                size_t reserved_size, size_t dyn_size,
1420                                size_t atom_size,
1421                                pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
1422{
1423        static int group_map[NR_CPUS] __initdata;
1424        static int group_cnt[NR_CPUS] __initdata;
1425        const size_t static_size = __per_cpu_end - __per_cpu_start;
1426        int nr_groups = 1, nr_units = 0;
1427        size_t size_sum, min_unit_size, alloc_size;
1428        int upa, max_upa, uninitialized_var(best_upa);  /* units_per_alloc */
1429        int last_allocs, group, unit;
1430        unsigned int cpu, tcpu;
1431        struct pcpu_alloc_info *ai;
1432        unsigned int *cpu_map;
1433
1434        /* this function may be called multiple times */
1435        memset(group_map, 0, sizeof(group_map));
1436        memset(group_cnt, 0, sizeof(group_cnt));
1437
1438        /* calculate size_sum and ensure dyn_size is enough for early alloc */
1439        size_sum = PFN_ALIGN(static_size + reserved_size +
1440                            max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
1441        dyn_size = size_sum - static_size - reserved_size;
1442
1443        /*
1444         * Determine min_unit_size, alloc_size and max_upa such that
1445         * alloc_size is multiple of atom_size and is the smallest
1446         * which can accommodate 4k aligned segments which are equal to
1447         * or larger than min_unit_size.
1448         */
1449        min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
1450
1451        alloc_size = roundup(min_unit_size, atom_size);
1452        upa = alloc_size / min_unit_size;
1453        while (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
1454                upa--;
1455        max_upa = upa;
1456
1457        /* group cpus according to their proximity */
1458        for_each_possible_cpu(cpu) {
1459                group = 0;
1460        next_group:
1461                for_each_possible_cpu(tcpu) {
1462                        if (cpu == tcpu)
1463                                break;
1464                        if (group_map[tcpu] == group && cpu_distance_fn &&
1465                            (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE ||
1466                             cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) {
1467                                group++;
1468                                nr_groups = max(nr_groups, group + 1);
1469                                goto next_group;
1470                        }
1471                }
1472                group_map[cpu] = group;
1473                group_cnt[group]++;
1474        }
1475
1476        /*
1477         * Expand unit size until address space usage goes over 75%
1478         * and then as much as possible without using more address
1479         * space.
1480         */
1481        last_allocs = INT_MAX;
1482        for (upa = max_upa; upa; upa--) {
1483                int allocs = 0, wasted = 0;
1484
1485                if (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
1486                        continue;
1487
1488                for (group = 0; group < nr_groups; group++) {
1489                        int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
1490                        allocs += this_allocs;
1491                        wasted += this_allocs * upa - group_cnt[group];
1492                }
1493
1494                /*
1495                 * Don't accept if wastage is over 1/3.  The
1496                 * greater-than comparison ensures upa==1 always
1497                 * passes the following check.
1498                 */
1499                if (wasted > num_possible_cpus() / 3)
1500                        continue;
1501
1502                /* and then don't consume more memory */
1503                if (allocs > last_allocs)
1504                        break;
1505                last_allocs = allocs;
1506                best_upa = upa;
1507        }
1508        upa = best_upa;
1509
1510        /* allocate and fill alloc_info */
1511        for (group = 0; group < nr_groups; group++)
1512                nr_units += roundup(group_cnt[group], upa);
1513
1514        ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
1515        if (!ai)
1516                return ERR_PTR(-ENOMEM);
1517        cpu_map = ai->groups[0].cpu_map;
1518
1519        for (group = 0; group < nr_groups; group++) {
1520                ai->groups[group].cpu_map = cpu_map;
1521                cpu_map += roundup(group_cnt[group], upa);
1522        }
1523
1524        ai->static_size = static_size;
1525        ai->reserved_size = reserved_size;
1526        ai->dyn_size = dyn_size;
1527        ai->unit_size = alloc_size / upa;
1528        ai->atom_size = atom_size;
1529        ai->alloc_size = alloc_size;
1530
1531        for (group = 0, unit = 0; group_cnt[group]; group++) {
1532                struct pcpu_group_info *gi = &ai->groups[group];
1533
1534                /*
1535                 * Initialize base_offset as if all groups are located
1536                 * back-to-back.  The caller should update this to
1537                 * reflect actual allocation.
1538                 */
1539                gi->base_offset = unit * ai->unit_size;
1540
1541                for_each_possible_cpu(cpu)
1542                        if (group_map[cpu] == group)
1543                                gi->cpu_map[gi->nr_units++] = cpu;
1544                gi->nr_units = roundup(gi->nr_units, upa);
1545                unit += gi->nr_units;
1546        }
1547        BUG_ON(unit != nr_units);
1548
1549        return ai;
1550}
1551#endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */
1552
1553#if defined(BUILD_EMBED_FIRST_CHUNK)
1554/**
1555 * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
1556 * @reserved_size: the size of reserved percpu area in bytes
1557 * @dyn_size: minimum free size for dynamic allocation in bytes
1558 * @atom_size: allocation atom size
1559 * @cpu_distance_fn: callback to determine distance between cpus, optional
1560 * @alloc_fn: function to allocate percpu page
1561 * @free_fn: function to free percpu page
1562 *
1563 * This is a helper to ease setting up embedded first percpu chunk and
1564 * can be called where pcpu_setup_first_chunk() is expected.
1565 *
1566 * If this function is used to setup the first chunk, it is allocated
1567 * by calling @alloc_fn and used as-is without being mapped into
1568 * vmalloc area.  Allocations are always whole multiples of @atom_size
1569 * aligned to @atom_size.
1570 *
1571 * This enables the first chunk to piggy back on the linear physical
1572 * mapping which often uses larger page size.  Please note that this
1573 * can result in very sparse cpu->unit mapping on NUMA machines thus
1574 * requiring large vmalloc address space.  Don't use this allocator if
1575 * vmalloc space is not orders of magnitude larger than distances
1576 * between node memory addresses (ie. 32bit NUMA machines).
1577 *
1578 * @dyn_size specifies the minimum dynamic area size.
1579 *
1580 * If the needed size is smaller than the minimum or specified unit
1581 * size, the leftover is returned using @free_fn.
1582 *
1583 * RETURNS:
1584 * 0 on success, -errno on failure.
1585 */
1586int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
1587                                  size_t atom_size,
1588                                  pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
1589                                  pcpu_fc_alloc_fn_t alloc_fn,
1590                                  pcpu_fc_free_fn_t free_fn)
1591{
1592        void *base = (void *)ULONG_MAX;
1593        void **areas = NULL;
1594        struct pcpu_alloc_info *ai;
1595        size_t size_sum, areas_size, max_distance;
1596        int group, i, rc;
1597
1598        ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
1599                                   cpu_distance_fn);
1600        if (IS_ERR(ai))
1601                return PTR_ERR(ai);
1602
1603        size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
1604        areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *));
1605
1606        areas = alloc_bootmem_nopanic(areas_size);
1607        if (!areas) {
1608                rc = -ENOMEM;
1609                goto out_free;
1610        }
1611
1612        /* allocate, copy and determine base address */
1613        for (group = 0; group < ai->nr_groups; group++) {
1614                struct pcpu_group_info *gi = &ai->groups[group];
1615                unsigned int cpu = NR_CPUS;
1616                void *ptr;
1617
1618                for (i = 0; i < gi->nr_units && cpu == NR_CPUS; i++)
1619                        cpu = gi->cpu_map[i];
1620                BUG_ON(cpu == NR_CPUS);
1621
1622                /* allocate space for the whole group */
1623                ptr = alloc_fn(cpu, gi->nr_units * ai->unit_size, atom_size);
1624                if (!ptr) {
1625                        rc = -ENOMEM;
1626                        goto out_free_areas;
1627                }
1628                areas[group] = ptr;
1629
1630                base = min(ptr, base);
1631
1632                for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) {
1633                        if (gi->cpu_map[i] == NR_CPUS) {
1634                                /* unused unit, free whole */
1635                                free_fn(ptr, ai->unit_size);
1636                                continue;
1637                        }
1638                        /* copy and return the unused part */
1639                        memcpy(ptr, __per_cpu_load, ai->static_size);
1640                        free_fn(ptr + size_sum, ai->unit_size - size_sum);
1641                }
1642        }
1643
1644        /* base address is now known, determine group base offsets */
1645        max_distance = 0;
1646        for (group = 0; group < ai->nr_groups; group++) {
1647                ai->groups[group].base_offset = areas[group] - base;
1648                max_distance = max_t(size_t, max_distance,
1649                                     ai->groups[group].base_offset);
1650        }
1651        max_distance += ai->unit_size;
1652
1653        /* warn if maximum distance is further than 75% of vmalloc space */
1654        if (max_distance > (VMALLOC_END - VMALLOC_START) * 3 / 4) {
1655                pr_warning("PERCPU: max_distance=0x%zx too large for vmalloc "
1656                           "space 0x%lx\n", max_distance,
1657                           (unsigned long)(VMALLOC_END - VMALLOC_START));
1658#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
1659                /* and fail if we have fallback */
1660                rc = -EINVAL;
1661                goto out_free;
1662#endif
1663        }
1664
1665        pr_info("PERCPU: Embedded %zu pages/cpu @%p s%zu r%zu d%zu u%zu\n",
1666                PFN_DOWN(size_sum), base, ai->static_size, ai->reserved_size,
1667                ai->dyn_size, ai->unit_size);
1668
1669        rc = pcpu_setup_first_chunk(ai, base);
1670        goto out_free;
1671
1672out_free_areas:
1673        for (group = 0; group < ai->nr_groups; group++)
1674                free_fn(areas[group],
1675                        ai->groups[group].nr_units * ai->unit_size);
1676out_free:
1677        pcpu_free_alloc_info(ai);
1678        if (areas)
1679                free_bootmem(__pa(areas), areas_size);
1680        return rc;
1681}
1682#endif /* BUILD_EMBED_FIRST_CHUNK */
1683
1684#ifdef BUILD_PAGE_FIRST_CHUNK
1685/**
1686 * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
1687 * @reserved_size: the size of reserved percpu area in bytes
1688 * @alloc_fn: function to allocate percpu page, always called with PAGE_SIZE
1689 * @free_fn: function to free percpu page, always called with PAGE_SIZE
1690 * @populate_pte_fn: function to populate pte
1691 *
1692 * This is a helper to ease setting up page-remapped first percpu
1693 * chunk and can be called where pcpu_setup_first_chunk() is expected.
1694 *
1695 * This is the basic allocator.  Static percpu area is allocated
1696 * page-by-page into vmalloc area.
1697 *
1698 * RETURNS:
1699 * 0 on success, -errno on failure.
1700 */
1701int __init pcpu_page_first_chunk(size_t reserved_size,
1702                                 pcpu_fc_alloc_fn_t alloc_fn,
1703                                 pcpu_fc_free_fn_t free_fn,
1704                                 pcpu_fc_populate_pte_fn_t populate_pte_fn)
1705{
1706        static struct vm_struct vm;
1707        struct pcpu_alloc_info *ai;
1708        char psize_str[16];
1709        int unit_pages;
1710        size_t pages_size;
1711        struct page **pages;
1712        int unit, i, j, rc;
1713
1714        snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);
1715
1716        ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL);
1717        if (IS_ERR(ai))
1718                return PTR_ERR(ai);
1719        BUG_ON(ai->nr_groups != 1);
1720        BUG_ON(ai->groups[0].nr_units != num_possible_cpus());
1721
1722        unit_pages = ai->unit_size >> PAGE_SHIFT;
1723
1724        /* unaligned allocations can't be freed, round up to page size */
1725        pages_size = PFN_ALIGN(unit_pages * num_possible_cpus() *
1726                               sizeof(pages[0]));
1727        pages = alloc_bootmem(pages_size);
1728
1729        /* allocate pages */
1730        j = 0;
1731        for (unit = 0; unit < num_possible_cpus(); unit++)
1732                for (i = 0; i < unit_pages; i++) {
1733                        unsigned int cpu = ai->groups[0].cpu_map[unit];
1734                        void *ptr;
1735
1736                        ptr = alloc_fn(cpu, PAGE_SIZE, PAGE_SIZE);
1737                        if (!ptr) {
1738                                pr_warning("PERCPU: failed to allocate %s page "
1739                                           "for cpu%u\n", psize_str, cpu);
1740                                goto enomem;
1741                        }
1742                        pages[j++] = virt_to_page(ptr);
1743                }
1744
1745        /* allocate vm area, map the pages and copy static data */
1746        vm.flags = VM_ALLOC;
1747        vm.size = num_possible_cpus() * ai->unit_size;
1748        vm_area_register_early(&vm, PAGE_SIZE);
1749
1750        for (unit = 0; unit < num_possible_cpus(); unit++) {
1751                unsigned long unit_addr =
1752                        (unsigned long)vm.addr + unit * ai->unit_size;
1753
1754                for (i = 0; i < unit_pages; i++)
1755                        populate_pte_fn(unit_addr + (i << PAGE_SHIFT));
1756
1757                /* pte already populated, the following shouldn't fail */
1758                rc = __pcpu_map_pages(unit_addr, &pages[unit * unit_pages],
1759                                      unit_pages);
1760                if (rc < 0)
1761                        panic("failed to map percpu area, err=%d\n", rc);
1762
1763                /*
1764                 * FIXME: Archs with virtual cache should flush local
1765                 * cache for the linear mapping here - something
1766                 * equivalent to flush_cache_vmap() on the local cpu.
1767                 * flush_cache_vmap() can't be used as most supporting
1768                 * data structures are not set up yet.
1769                 */
1770
1771                /* copy static data */
1772                memcpy((void *)unit_addr, __per_cpu_load, ai->static_size);
1773        }
1774
1775        /* we're ready, commit */
1776        pr_info("PERCPU: %d %s pages/cpu @%p s%zu r%zu d%zu\n",
1777                unit_pages, psize_str, vm.addr, ai->static_size,
1778                ai->reserved_size, ai->dyn_size);
1779
1780        rc = pcpu_setup_first_chunk(ai, vm.addr);
1781        goto out_free_ar;
1782
1783enomem:
1784        while (--j >= 0)
1785                free_fn(page_address(pages[j]), PAGE_SIZE);
1786        rc = -ENOMEM;
1787out_free_ar:
1788        free_bootmem(__pa(pages), pages_size);
1789        pcpu_free_alloc_info(ai);
1790        return rc;
1791}
1792#endif /* BUILD_PAGE_FIRST_CHUNK */
1793
1794#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
1795/*
1796 * Generic SMP percpu area setup.
1797 *
1798 * The embedding helper is used because its behavior closely resembles
1799 * the original non-dynamic generic percpu area setup.  This is
1800 * important because many archs have addressing restrictions and might
1801 * fail if the percpu area is located far away from the previous
1802 * location.  As an added bonus, in non-NUMA cases, embedding is
1803 * generally a good idea TLB-wise because percpu area can piggy back
1804 * on the physical linear memory mapping which uses large page
1805 * mappings on applicable archs.
1806 */
1807unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
1808EXPORT_SYMBOL(__per_cpu_offset);
1809
1810static void * __init pcpu_dfl_fc_alloc(unsigned int cpu, size_t size,
1811                                       size_t align)
1812{
1813        return __alloc_bootmem_nopanic(size, align, __pa(MAX_DMA_ADDRESS));
1814}
1815
1816static void __init pcpu_dfl_fc_free(void *ptr, size_t size)
1817{
1818        free_bootmem(__pa(ptr), size);
1819}
1820
1821void __init setup_per_cpu_areas(void)
1822{
1823        unsigned long delta;
1824        unsigned int cpu;
1825        int rc;
1826
1827        /*
1828         * Always reserve area for module percpu variables.  That's
1829         * what the legacy allocator did.
1830         */
1831        rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
1832                                    PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL,
1833                                    pcpu_dfl_fc_alloc, pcpu_dfl_fc_free);
1834        if (rc < 0)
1835                panic("Failed to initialize percpu areas.");
1836
1837        delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
1838        for_each_possible_cpu(cpu)
1839                __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
1840}
1841#endif  /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
1842
1843#else   /* CONFIG_SMP */
1844
1845/*
1846 * UP percpu area setup.
1847 *
1848 * UP always uses km-based percpu allocator with identity mapping.
1849 * Static percpu variables are indistinguishable from the usual static
1850 * variables and don't require any special preparation.
1851 */
1852void __init setup_per_cpu_areas(void)
1853{
1854        const size_t unit_size =
1855                roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
1856                                         PERCPU_DYNAMIC_RESERVE));
1857        struct pcpu_alloc_info *ai;
1858        void *fc;
1859
1860        ai = pcpu_alloc_alloc_info(1, 1);
1861        fc = __alloc_bootmem(unit_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
1862        if (!ai || !fc)
1863                panic("Failed to allocate memory for percpu areas.");
1864
1865        ai->dyn_size = unit_size;
1866        ai->unit_size = unit_size;
1867        ai->atom_size = unit_size;
1868        ai->alloc_size = unit_size;
1869        ai->groups[0].nr_units = 1;
1870        ai->groups[0].cpu_map[0] = 0;
1871
1872        if (pcpu_setup_first_chunk(ai, fc) < 0)
1873                panic("Failed to initialize percpu areas.");
1874}
1875
1876#endif  /* CONFIG_SMP */
1877
1878/*
1879 * First and reserved chunks are initialized with temporary allocation
1880 * map in initdata so that they can be used before slab is online.
1881 * This function is called after slab is brought up and replaces those
1882 * with properly allocated maps.
1883 */
1884void __init percpu_init_late(void)
1885{
1886        struct pcpu_chunk *target_chunks[] =
1887                { pcpu_first_chunk, pcpu_reserved_chunk, NULL };
1888        struct pcpu_chunk *chunk;
1889        unsigned long flags;
1890        int i;
1891
1892        for (i = 0; (chunk = target_chunks[i]); i++) {
1893                int *map;
1894                const size_t size = PERCPU_DYNAMIC_EARLY_SLOTS * sizeof(map[0]);
1895
1896                BUILD_BUG_ON(size > PAGE_SIZE);
1897
1898                map = pcpu_mem_alloc(size);
1899                BUG_ON(!map);
1900
1901                spin_lock_irqsave(&pcpu_lock, flags);
1902                memcpy(map, chunk->map, size);
1903                chunk->map = map;
1904                spin_unlock_irqrestore(&pcpu_lock, flags);
1905        }
1906}
1907
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