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Diffstat (limited to 'mm/percpu.c')
| -rw-r--r-- | mm/percpu.c | 2793 |
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diff --git a/mm/percpu.c b/mm/percpu.c new file mode 100644 index 000000000..0151f276a --- /dev/null +++ b/mm/percpu.c @@ -0,0 +1,2793 @@ +/* + * mm/percpu.c - percpu memory allocator + * + * Copyright (C) 2009 SUSE Linux Products GmbH + * Copyright (C) 2009 Tejun Heo <tj@kernel.org> + * + * Copyright (C) 2017 Facebook Inc. + * Copyright (C) 2017 Dennis Zhou <dennisszhou@gmail.com> + * + * This file is released under the GPLv2 license. + * + * The percpu allocator handles both static and dynamic areas. Percpu + * areas are allocated in chunks which are divided into units. There is + * a 1-to-1 mapping for units to possible cpus. These units are grouped + * based on NUMA properties of the machine. + * + * c0 c1 c2 + * ------------------- ------------------- ------------ + * | u0 | u1 | u2 | u3 | | u0 | u1 | u2 | u3 | | u0 | u1 | u + * ------------------- ...... ------------------- .... ------------ + * + * Allocation is done by offsets into a unit's address space. Ie., an + * area of 512 bytes at 6k in c1 occupies 512 bytes at 6k in c1:u0, + * c1:u1, c1:u2, etc. On NUMA machines, the mapping may be non-linear + * and even sparse. Access is handled by configuring percpu base + * registers according to the cpu to unit mappings and offsetting the + * base address using pcpu_unit_size. + * + * There is special consideration for the first chunk which must handle + * the static percpu variables in the kernel image as allocation services + * are not online yet. In short, the first chunk is structured like so: + * + * <Static | [Reserved] | Dynamic> + * + * The static data is copied from the original section managed by the + * linker. The reserved section, if non-zero, primarily manages static + * percpu variables from kernel modules. Finally, the dynamic section + * takes care of normal allocations. + * + * The allocator organizes chunks into lists according to free size and + * tries to allocate from the fullest chunk first. Each chunk is managed + * by a bitmap with metadata blocks. The allocation map is updated on + * every allocation and free to reflect the current state while the boundary + * map is only updated on allocation. Each metadata block contains + * information to help mitigate the need to iterate over large portions + * of the bitmap. The reverse mapping from page to chunk is stored in + * the page's index. Lastly, units are lazily backed and grow in unison. + * + * There is a unique conversion that goes on here between bytes and bits. + * Each bit represents a fragment of size PCPU_MIN_ALLOC_SIZE. The chunk + * tracks the number of pages it is responsible for in nr_pages. Helper + * functions are used to convert from between the bytes, bits, and blocks. + * All hints are managed in bits unless explicitly stated. + * + * To use this allocator, arch code should do the following: + * + * - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate + * regular address to percpu pointer and back if they need to be + * different from the default + * + * - use pcpu_setup_first_chunk() during percpu area initialization to + * setup the first chunk containing the kernel static percpu area + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/bitmap.h> +#include <linux/bootmem.h> +#include <linux/err.h> +#include <linux/lcm.h> +#include <linux/list.h> +#include <linux/log2.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/percpu.h> +#include <linux/pfn.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/vmalloc.h> +#include <linux/workqueue.h> +#include <linux/kmemleak.h> +#include <linux/sched.h> + +#include <asm/cacheflush.h> +#include <asm/sections.h> +#include <asm/tlbflush.h> +#include <asm/io.h> + +#define CREATE_TRACE_POINTS +#include <trace/events/percpu.h> + +#include "percpu-internal.h" + +/* the slots are sorted by free bytes left, 1-31 bytes share the same slot */ +#define PCPU_SLOT_BASE_SHIFT 5 + +#define PCPU_EMPTY_POP_PAGES_LOW 2 +#define PCPU_EMPTY_POP_PAGES_HIGH 4 + +#ifdef CONFIG_SMP +/* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */ +#ifndef __addr_to_pcpu_ptr +#define __addr_to_pcpu_ptr(addr) \ + (void __percpu *)((unsigned long)(addr) - \ + (unsigned long)pcpu_base_addr + \ + (unsigned long)__per_cpu_start) +#endif +#ifndef __pcpu_ptr_to_addr +#define __pcpu_ptr_to_addr(ptr) \ + (void __force *)((unsigned long)(ptr) + \ + (unsigned long)pcpu_base_addr - \ + (unsigned long)__per_cpu_start) +#endif +#else /* CONFIG_SMP */ +/* on UP, it's always identity mapped */ +#define __addr_to_pcpu_ptr(addr) (void __percpu *)(addr) +#define __pcpu_ptr_to_addr(ptr) (void __force *)(ptr) +#endif /* CONFIG_SMP */ + +static int pcpu_unit_pages __ro_after_init; +static int pcpu_unit_size __ro_after_init; +static int pcpu_nr_units __ro_after_init; +static int pcpu_atom_size __ro_after_init; +int pcpu_nr_slots __ro_after_init; +static size_t pcpu_chunk_struct_size __ro_after_init; + +/* cpus with the lowest and highest unit addresses */ +static unsigned int pcpu_low_unit_cpu __ro_after_init; +static unsigned int pcpu_high_unit_cpu __ro_after_init; + +/* the address of the first chunk which starts with the kernel static area */ +void *pcpu_base_addr __ro_after_init; +EXPORT_SYMBOL_GPL(pcpu_base_addr); + +static const int *pcpu_unit_map __ro_after_init; /* cpu -> unit */ +const unsigned long *pcpu_unit_offsets __ro_after_init; /* cpu -> unit offset */ + +/* group information, used for vm allocation */ +static int pcpu_nr_groups __ro_after_init; +static const unsigned long *pcpu_group_offsets __ro_after_init; +static const size_t *pcpu_group_sizes __ro_after_init; + +/* + * The first chunk which always exists. Note that unlike other + * chunks, this one can be allocated and mapped in several different + * ways and thus often doesn't live in the vmalloc area. + */ +struct pcpu_chunk *pcpu_first_chunk __ro_after_init; + +/* + * Optional reserved chunk. This chunk reserves part of the first + * chunk and serves it for reserved allocations. When the reserved + * region doesn't exist, the following variable is NULL. + */ +struct pcpu_chunk *pcpu_reserved_chunk __ro_after_init; + +DEFINE_SPINLOCK(pcpu_lock); /* all internal data structures */ +static DEFINE_MUTEX(pcpu_alloc_mutex); /* chunk create/destroy, [de]pop, map ext */ + +struct list_head *pcpu_slot __ro_after_init; /* chunk list slots */ + +/* chunks which need their map areas extended, protected by pcpu_lock */ +static LIST_HEAD(pcpu_map_extend_chunks); + +/* + * The number of empty populated pages, protected by pcpu_lock. The + * reserved chunk doesn't contribute to the count. + */ +int pcpu_nr_empty_pop_pages; + +/* + * The number of populated pages in use by the allocator, protected by + * pcpu_lock. This number is kept per a unit per chunk (i.e. when a page gets + * allocated/deallocated, it is allocated/deallocated in all units of a chunk + * and increments/decrements this count by 1). + */ +static unsigned long pcpu_nr_populated; + +/* + * Balance work is used to populate or destroy chunks asynchronously. We + * try to keep the number of populated free pages between + * PCPU_EMPTY_POP_PAGES_LOW and HIGH for atomic allocations and at most one + * empty chunk. + */ +static void pcpu_balance_workfn(struct work_struct *work); +static DECLARE_WORK(pcpu_balance_work, pcpu_balance_workfn); +static bool pcpu_async_enabled __read_mostly; +static bool pcpu_atomic_alloc_failed; + +static void pcpu_schedule_balance_work(void) +{ + if (pcpu_async_enabled) + schedule_work(&pcpu_balance_work); +} + +/** + * pcpu_addr_in_chunk - check if the address is served from this chunk + * @chunk: chunk of interest + * @addr: percpu address + * + * RETURNS: + * True if the address is served from this chunk. + */ +static bool pcpu_addr_in_chunk(struct pcpu_chunk *chunk, void *addr) +{ + void *start_addr, *end_addr; + + if (!chunk) + return false; + + start_addr = chunk->base_addr + chunk->start_offset; + end_addr = chunk->base_addr + chunk->nr_pages * PAGE_SIZE - + chunk->end_offset; + + return addr >= start_addr && addr < end_addr; +} + +static int __pcpu_size_to_slot(int size) +{ + int highbit = fls(size); /* size is in bytes */ + return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1); +} + +static int pcpu_size_to_slot(int size) +{ + if (size == pcpu_unit_size) + return pcpu_nr_slots - 1; + return __pcpu_size_to_slot(size); +} + +static int pcpu_chunk_slot(const struct pcpu_chunk *chunk) +{ + if (chunk->free_bytes < PCPU_MIN_ALLOC_SIZE || chunk->contig_bits == 0) + return 0; + + return pcpu_size_to_slot(chunk->free_bytes); +} + +/* set the pointer to a chunk in a page struct */ +static void pcpu_set_page_chunk(struct page *page, struct pcpu_chunk *pcpu) +{ + page->index = (unsigned long)pcpu; +} + +/* obtain pointer to a chunk from a page struct */ +static struct pcpu_chunk *pcpu_get_page_chunk(struct page *page) +{ + return (struct pcpu_chunk *)page->index; +} + +static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx) +{ + return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx; +} + +static unsigned long pcpu_unit_page_offset(unsigned int cpu, int page_idx) +{ + return pcpu_unit_offsets[cpu] + (page_idx << PAGE_SHIFT); +} + +static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk, + unsigned int cpu, int page_idx) +{ + return (unsigned long)chunk->base_addr + + pcpu_unit_page_offset(cpu, page_idx); +} + +static void pcpu_next_unpop(unsigned long *bitmap, int *rs, int *re, int end) +{ + *rs = find_next_zero_bit(bitmap, end, *rs); + *re = find_next_bit(bitmap, end, *rs + 1); +} + +static void pcpu_next_pop(unsigned long *bitmap, int *rs, int *re, int end) +{ + *rs = find_next_bit(bitmap, end, *rs); + *re = find_next_zero_bit(bitmap, end, *rs + 1); +} + +/* + * Bitmap region iterators. Iterates over the bitmap between + * [@start, @end) in @chunk. @rs and @re should be integer variables + * and will be set to start and end index of the current free region. + */ +#define pcpu_for_each_unpop_region(bitmap, rs, re, start, end) \ + for ((rs) = (start), pcpu_next_unpop((bitmap), &(rs), &(re), (end)); \ + (rs) < (re); \ + (rs) = (re) + 1, pcpu_next_unpop((bitmap), &(rs), &(re), (end))) + +#define pcpu_for_each_pop_region(bitmap, rs, re, start, end) \ + for ((rs) = (start), pcpu_next_pop((bitmap), &(rs), &(re), (end)); \ + (rs) < (re); \ + (rs) = (re) + 1, pcpu_next_pop((bitmap), &(rs), &(re), (end))) + +/* + * The following are helper functions to help access bitmaps and convert + * between bitmap offsets to address offsets. + */ +static unsigned long *pcpu_index_alloc_map(struct pcpu_chunk *chunk, int index) +{ + return chunk->alloc_map + + (index * PCPU_BITMAP_BLOCK_BITS / BITS_PER_LONG); +} + +static unsigned long pcpu_off_to_block_index(int off) +{ + return off / PCPU_BITMAP_BLOCK_BITS; +} + +static unsigned long pcpu_off_to_block_off(int off) +{ + return off & (PCPU_BITMAP_BLOCK_BITS - 1); +} + +static unsigned long pcpu_block_off_to_off(int index, int off) +{ + return index * PCPU_BITMAP_BLOCK_BITS + off; +} + +/** + * pcpu_next_md_free_region - finds the next hint free area + * @chunk: chunk of interest + * @bit_off: chunk offset + * @bits: size of free area + * + * Helper function for pcpu_for_each_md_free_region. It checks + * block->contig_hint and performs aggregation across blocks to find the + * next hint. It modifies bit_off and bits in-place to be consumed in the + * loop. + */ +static void pcpu_next_md_free_region(struct pcpu_chunk *chunk, int *bit_off, + int *bits) +{ + int i = pcpu_off_to_block_index(*bit_off); + int block_off = pcpu_off_to_block_off(*bit_off); + struct pcpu_block_md *block; + + *bits = 0; + for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk); + block++, i++) { + /* handles contig area across blocks */ + if (*bits) { + *bits += block->left_free; + if (block->left_free == PCPU_BITMAP_BLOCK_BITS) + continue; + return; + } + + /* + * This checks three things. First is there a contig_hint to + * check. Second, have we checked this hint before by + * comparing the block_off. Third, is this the same as the + * right contig hint. In the last case, it spills over into + * the next block and should be handled by the contig area + * across blocks code. + */ + *bits = block->contig_hint; + if (*bits && block->contig_hint_start >= block_off && + *bits + block->contig_hint_start < PCPU_BITMAP_BLOCK_BITS) { + *bit_off = pcpu_block_off_to_off(i, + block->contig_hint_start); + return; + } + /* reset to satisfy the second predicate above */ + block_off = 0; + + *bits = block->right_free; + *bit_off = (i + 1) * PCPU_BITMAP_BLOCK_BITS - block->right_free; + } +} + +/** + * pcpu_next_fit_region - finds fit areas for a given allocation request + * @chunk: chunk of interest + * @alloc_bits: size of allocation + * @align: alignment of area (max PAGE_SIZE) + * @bit_off: chunk offset + * @bits: size of free area + * + * Finds the next free region that is viable for use with a given size and + * alignment. This only returns if there is a valid area to be used for this + * allocation. block->first_free is returned if the allocation request fits + * within the block to see if the request can be fulfilled prior to the contig + * hint. + */ +static void pcpu_next_fit_region(struct pcpu_chunk *chunk, int alloc_bits, + int align, int *bit_off, int *bits) +{ + int i = pcpu_off_to_block_index(*bit_off); + int block_off = pcpu_off_to_block_off(*bit_off); + struct pcpu_block_md *block; + + *bits = 0; + for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk); + block++, i++) { + /* handles contig area across blocks */ + if (*bits) { + *bits += block->left_free; + if (*bits >= alloc_bits) + return; + if (block->left_free == PCPU_BITMAP_BLOCK_BITS) + continue; + } + + /* check block->contig_hint */ + *bits = ALIGN(block->contig_hint_start, align) - + block->contig_hint_start; + /* + * This uses the block offset to determine if this has been + * checked in the prior iteration. + */ + if (block->contig_hint && + block->contig_hint_start >= block_off && + block->contig_hint >= *bits + alloc_bits) { + *bits += alloc_bits + block->contig_hint_start - + block->first_free; + *bit_off = pcpu_block_off_to_off(i, block->first_free); + return; + } + /* reset to satisfy the second predicate above */ + block_off = 0; + + *bit_off = ALIGN(PCPU_BITMAP_BLOCK_BITS - block->right_free, + align); + *bits = PCPU_BITMAP_BLOCK_BITS - *bit_off; + *bit_off = pcpu_block_off_to_off(i, *bit_off); + if (*bits >= alloc_bits) + return; + } + + /* no valid offsets were found - fail condition */ + *bit_off = pcpu_chunk_map_bits(chunk); +} + +/* + * Metadata free area iterators. These perform aggregation of free areas + * based on the metadata blocks and return the offset @bit_off and size in + * bits of the free area @bits. pcpu_for_each_fit_region only returns when + * a fit is found for the allocation request. + */ +#define pcpu_for_each_md_free_region(chunk, bit_off, bits) \ + for (pcpu_next_md_free_region((chunk), &(bit_off), &(bits)); \ + (bit_off) < pcpu_chunk_map_bits((chunk)); \ + (bit_off) += (bits) + 1, \ + pcpu_next_md_free_region((chunk), &(bit_off), &(bits))) + +#define pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) \ + for (pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \ + &(bits)); \ + (bit_off) < pcpu_chunk_map_bits((chunk)); \ + (bit_off) += (bits), \ + pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \ + &(bits))) + +/** + * pcpu_mem_zalloc - allocate memory + * @size: bytes to allocate + * @gfp: allocation flags + * + * Allocate @size bytes. If @size is smaller than PAGE_SIZE, + * kzalloc() is used; otherwise, the equivalent of vzalloc() is used. + * This is to facilitate passing through whitelisted flags. The + * returned memory is always zeroed. + * + * RETURNS: + * Pointer to the allocated area on success, NULL on failure. + */ +static void *pcpu_mem_zalloc(size_t size, gfp_t gfp) +{ + if (WARN_ON_ONCE(!slab_is_available())) + return NULL; + + if (size <= PAGE_SIZE) + return kzalloc(size, gfp); + else + return __vmalloc(size, gfp | __GFP_ZERO, PAGE_KERNEL); +} + +/** + * pcpu_mem_free - free memory + * @ptr: memory to free + * + * Free @ptr. @ptr should have been allocated using pcpu_mem_zalloc(). + */ +static void pcpu_mem_free(void *ptr) +{ + kvfree(ptr); +} + +/** + * pcpu_chunk_relocate - put chunk in the appropriate chunk slot + * @chunk: chunk of interest + * @oslot: the previous slot it was on + * + * This function is called after an allocation or free changed @chunk. + * New slot according to the changed state is determined and @chunk is + * moved to the slot. Note that the reserved chunk is never put on + * chunk slots. + * + * CONTEXT: + * pcpu_lock. + */ +static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot) +{ + int nslot = pcpu_chunk_slot(chunk); + + if (chunk != pcpu_reserved_chunk && oslot != nslot) { + if (oslot < nslot) + list_move(&chunk->list, &pcpu_slot[nslot]); + else + list_move_tail(&chunk->list, &pcpu_slot[nslot]); + } +} + +/** + * pcpu_cnt_pop_pages- counts populated backing pages in range + * @chunk: chunk of interest + * @bit_off: start offset + * @bits: size of area to check + * + * Calculates the number of populated pages in the region + * [page_start, page_end). This keeps track of how many empty populated + * pages are available and decide if async work should be scheduled. + * + * RETURNS: + * The nr of populated pages. + */ +static inline int pcpu_cnt_pop_pages(struct pcpu_chunk *chunk, int bit_off, + int bits) +{ + int page_start = PFN_UP(bit_off * PCPU_MIN_ALLOC_SIZE); + int page_end = PFN_DOWN((bit_off + bits) * PCPU_MIN_ALLOC_SIZE); + + if (page_start >= page_end) + return 0; + + /* + * bitmap_weight counts the number of bits set in a bitmap up to + * the specified number of bits. This is counting the populated + * pages up to page_end and then subtracting the populated pages + * up to page_start to count the populated pages in + * [page_start, page_end). + */ + return bitmap_weight(chunk->populated, page_end) - + bitmap_weight(chunk->populated, page_start); +} + +/** + * pcpu_chunk_update - updates the chunk metadata given a free area + * @chunk: chunk of interest + * @bit_off: chunk offset + * @bits: size of free area + * + * This updates the chunk's contig hint and starting offset given a free area. + * Choose the best starting offset if the contig hint is equal. + */ +static void pcpu_chunk_update(struct pcpu_chunk *chunk, int bit_off, int bits) +{ + if (bits > chunk->contig_bits) { + chunk->contig_bits_start = bit_off; + chunk->contig_bits = bits; + } else if (bits == chunk->contig_bits && chunk->contig_bits_start && + (!bit_off || + __ffs(bit_off) > __ffs(chunk->contig_bits_start))) { + /* use the start with the best alignment */ + chunk->contig_bits_start = bit_off; + } +} + +/** + * pcpu_chunk_refresh_hint - updates metadata about a chunk + * @chunk: chunk of interest + * + * Iterates over the metadata blocks to find the largest contig area. + * It also counts the populated pages and uses the delta to update the + * global count. + * + * Updates: + * chunk->contig_bits + * chunk->contig_bits_start + * nr_empty_pop_pages (chunk and global) + */ +static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk) +{ + int bit_off, bits, nr_empty_pop_pages; + + /* clear metadata */ + chunk->contig_bits = 0; + + bit_off = chunk->first_bit; + bits = nr_empty_pop_pages = 0; + pcpu_for_each_md_free_region(chunk, bit_off, bits) { + pcpu_chunk_update(chunk, bit_off, bits); + + nr_empty_pop_pages += pcpu_cnt_pop_pages(chunk, bit_off, bits); + } + + /* + * Keep track of nr_empty_pop_pages. + * + * The chunk maintains the previous number of free pages it held, + * so the delta is used to update the global counter. The reserved + * chunk is not part of the free page count as they are populated + * at init and are special to serving reserved allocations. + */ + if (chunk != pcpu_reserved_chunk) + pcpu_nr_empty_pop_pages += + (nr_empty_pop_pages - chunk->nr_empty_pop_pages); + + chunk->nr_empty_pop_pages = nr_empty_pop_pages; +} + +/** + * pcpu_block_update - updates a block given a free area + * @block: block of interest + * @start: start offset in block + * @end: end offset in block + * + * Updates a block given a known free area. The region [start, end) is + * expected to be the entirety of the free area within a block. Chooses + * the best starting offset if the contig hints are equal. + */ +static void pcpu_block_update(struct pcpu_block_md *block, int start, int end) +{ + int contig = end - start; + + block->first_free = min(block->first_free, start); + if (start == 0) + block->left_free = contig; + + if (end == PCPU_BITMAP_BLOCK_BITS) + block->right_free = contig; + + if (contig > block->contig_hint) { + block->contig_hint_start = start; + block->contig_hint = contig; + } else if (block->contig_hint_start && contig == block->contig_hint && + (!start || __ffs(start) > __ffs(block->contig_hint_start))) { + /* use the start with the best alignment */ + block->contig_hint_start = start; + } +} + +/** + * pcpu_block_refresh_hint + * @chunk: chunk of interest + * @index: index of the metadata block + * + * Scans over the block beginning at first_free and updates the block + * metadata accordingly. + */ +static void pcpu_block_refresh_hint(struct pcpu_chunk *chunk, int index) +{ + struct pcpu_block_md *block = chunk->md_blocks + index; + unsigned long *alloc_map = pcpu_index_alloc_map(chunk, index); + int rs, re; /* region start, region end */ + + /* clear hints */ + block->contig_hint = 0; + block->left_free = block->right_free = 0; + + /* iterate over free areas and update the contig hints */ + pcpu_for_each_unpop_region(alloc_map, rs, re, block->first_free, + PCPU_BITMAP_BLOCK_BITS) { + pcpu_block_update(block, rs, re); + } +} + +/** + * pcpu_block_update_hint_alloc - update hint on allocation path + * @chunk: chunk of interest + * @bit_off: chunk offset + * @bits: size of request + * + * Updates metadata for the allocation path. The metadata only has to be + * refreshed by a full scan iff the chunk's contig hint is broken. Block level + * scans are required if the block's contig hint is broken. + */ +static void pcpu_block_update_hint_alloc(struct pcpu_chunk *chunk, int bit_off, + int bits) +{ + struct pcpu_block_md *s_block, *e_block, *block; + int s_index, e_index; /* block indexes of the freed allocation */ + int s_off, e_off; /* block offsets of the freed allocation */ + + /* + * Calculate per block offsets. + * The calculation uses an inclusive range, but the resulting offsets + * are [start, end). e_index always points to the last block in the + * range. + */ + s_index = pcpu_off_to_block_index(bit_off); + e_index = pcpu_off_to_block_index(bit_off + bits - 1); + s_off = pcpu_off_to_block_off(bit_off); + e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1; + + s_block = chunk->md_blocks + s_index; + e_block = chunk->md_blocks + e_index; + + /* + * Update s_block. + * block->first_free must be updated if the allocation takes its place. + * If the allocation breaks the contig_hint, a scan is required to + * restore this hint. + */ + if (s_off == s_block->first_free) + s_block->first_free = find_next_zero_bit( + pcpu_index_alloc_map(chunk, s_index), + PCPU_BITMAP_BLOCK_BITS, + s_off + bits); + + if (s_off >= s_block->contig_hint_start && + s_off < s_block->contig_hint_start + s_block->contig_hint) { + /* block contig hint is broken - scan to fix it */ + pcpu_block_refresh_hint(chunk, s_index); + } else { + /* update left and right contig manually */ + s_block->left_free = min(s_block->left_free, s_off); + if (s_index == e_index) + s_block->right_free = min_t(int, s_block->right_free, + PCPU_BITMAP_BLOCK_BITS - e_off); + else + s_block->right_free = 0; + } + + /* + * Update e_block. + */ + if (s_index != e_index) { + /* + * When the allocation is across blocks, the end is along + * the left part of the e_block. + */ + e_block->first_free = find_next_zero_bit( + pcpu_index_alloc_map(chunk, e_index), + PCPU_BITMAP_BLOCK_BITS, e_off); + + if (e_off == PCPU_BITMAP_BLOCK_BITS) { + /* reset the block */ + e_block++; + } else { + if (e_off > e_block->contig_hint_start) { + /* contig hint is broken - scan to fix it */ + pcpu_block_refresh_hint(chunk, e_index); + } else { + e_block->left_free = 0; + e_block->right_free = + min_t(int, e_block->right_free, + PCPU_BITMAP_BLOCK_BITS - e_off); + } + } + + /* update in-between md_blocks */ + for (block = s_block + 1; block < e_block; block++) { + block->contig_hint = 0; + block->left_free = 0; + block->right_free = 0; + } + } + + /* + * The only time a full chunk scan is required is if the chunk + * contig hint is broken. Otherwise, it means a smaller space + * was used and therefore the chunk contig hint is still correct. + */ + if (bit_off >= chunk->contig_bits_start && + bit_off < chunk->contig_bits_start + chunk->contig_bits) + pcpu_chunk_refresh_hint(chunk); +} + +/** + * pcpu_block_update_hint_free - updates the block hints on the free path + * @chunk: chunk of interest + * @bit_off: chunk offset + * @bits: size of request + * + * Updates metadata for the allocation path. This avoids a blind block + * refresh by making use of the block contig hints. If this fails, it scans + * forward and backward to determine the extent of the free area. This is + * capped at the boundary of blocks. + * + * A chunk update is triggered if a page becomes free, a block becomes free, + * or the free spans across blocks. This tradeoff is to minimize iterating + * over the block metadata to update chunk->contig_bits. chunk->contig_bits + * may be off by up to a page, but it will never be more than the available + * space. If the contig hint is contained in one block, it will be accurate. + */ +static void pcpu_block_update_hint_free(struct pcpu_chunk *chunk, int bit_off, + int bits) +{ + struct pcpu_block_md *s_block, *e_block, *block; + int s_index, e_index; /* block indexes of the freed allocation */ + int s_off, e_off; /* block offsets of the freed allocation */ + int start, end; /* start and end of the whole free area */ + + /* + * Calculate per block offsets. + * The calculation uses an inclusive range, but the resulting offsets + * are [start, end). e_index always points to the last block in the + * range. + */ + s_index = pcpu_off_to_block_index(bit_off); + e_index = pcpu_off_to_block_index(bit_off + bits - 1); + s_off = pcpu_off_to_block_off(bit_off); + e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1; + + s_block = chunk->md_blocks + s_index; + e_block = chunk->md_blocks + e_index; + + /* + * Check if the freed area aligns with the block->contig_hint. + * If it does, then the scan to find the beginning/end of the + * larger free area can be avoided. + * + * start and end refer to beginning and end of the free area + * within each their respective blocks. This is not necessarily + * the entire free area as it may span blocks past the beginning + * or end of the block. + */ + start = s_off; + if (s_off == s_block->contig_hint + s_block->contig_hint_start) { + start = s_block->contig_hint_start; + } else { + /* + * Scan backwards to find the extent of the free area. + * find_last_bit returns the starting bit, so if the start bit + * is returned, that means there was no last bit and the + * remainder of the chunk is free. + */ + int l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index), + start); + start = (start == l_bit) ? 0 : l_bit + 1; + } + + end = e_off; + if (e_off == e_block->contig_hint_start) + end = e_block->contig_hint_start + e_block->contig_hint; + else + end = find_next_bit(pcpu_index_alloc_map(chunk, e_index), + PCPU_BITMAP_BLOCK_BITS, end); + + /* update s_block */ + e_off = (s_index == e_index) ? end : PCPU_BITMAP_BLOCK_BITS; + pcpu_block_update(s_block, start, e_off); + + /* freeing in the same block */ + if (s_index != e_index) { + /* update e_block */ + pcpu_block_update(e_block, 0, end); + + /* reset md_blocks in the middle */ + for (block = s_block + 1; block < e_block; block++) { + block->first_free = 0; + block->contig_hint_start = 0; + block->contig_hint = PCPU_BITMAP_BLOCK_BITS; + block->left_free = PCPU_BITMAP_BLOCK_BITS; + block->right_free = PCPU_BITMAP_BLOCK_BITS; + } + } + + /* + * Refresh chunk metadata when the free makes a page free, a block + * free, or spans across blocks. The contig hint may be off by up to + * a page, but if the hint is contained in a block, it will be accurate + * with the else condition below. + */ + if ((ALIGN_DOWN(end, min(PCPU_BITS_PER_PAGE, PCPU_BITMAP_BLOCK_BITS)) > + ALIGN(start, min(PCPU_BITS_PER_PAGE, PCPU_BITMAP_BLOCK_BITS))) || + s_index != e_index) + pcpu_chunk_refresh_hint(chunk); + else + pcpu_chunk_update(chunk, pcpu_block_off_to_off(s_index, start), + s_block->contig_hint); +} + +/** + * pcpu_is_populated - determines if the region is populated + * @chunk: chunk of interest + * @bit_off: chunk offset + * @bits: size of area + * @next_off: return value for the next offset to start searching + * + * For atomic allocations, check if the backing pages are populated. + * + * RETURNS: + * Bool if the backing pages are populated. + * next_index is to skip over unpopulated blocks in pcpu_find_block_fit. + */ +static bool pcpu_is_populated(struct pcpu_chunk *chunk, int bit_off, int bits, + int *next_off) +{ + int page_start, page_end, rs, re; + + page_start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE); + page_end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE); + + rs = page_start; + pcpu_next_unpop(chunk->populated, &rs, &re, page_end); + if (rs >= page_end) + return true; + + *next_off = re * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE; + return false; +} + +/** + * pcpu_find_block_fit - finds the block index to start searching + * @chunk: chunk of interest + * @alloc_bits: size of request in allocation units + * @align: alignment of area (max PAGE_SIZE bytes) + * @pop_only: use populated regions only + * + * Given a chunk and an allocation spec, find the offset to begin searching + * for a free region. This iterates over the bitmap metadata blocks to + * find an offset that will be guaranteed to fit the requirements. It is + * not quite first fit as if the allocation does not fit in the contig hint + * of a block or chunk, it is skipped. This errs on the side of caution + * to prevent excess iteration. Poor alignment can cause the allocator to + * skip over blocks and chunks that have valid free areas. + * + * RETURNS: + * The offset in the bitmap to begin searching. + * -1 if no offset is found. + */ +static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits, + size_t align, bool pop_only) +{ + int bit_off, bits, next_off; + + /* + * Check to see if the allocation can fit in the chunk's contig hint. + * This is an optimization to prevent scanning by assuming if it + * cannot fit in the global hint, there is memory pressure and creating + * a new chunk would happen soon. + */ + bit_off = ALIGN(chunk->contig_bits_start, align) - + chunk->contig_bits_start; + if (bit_off + alloc_bits > chunk->contig_bits) + return -1; + + bit_off = chunk->first_bit; + bits = 0; + pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) { + if (!pop_only || pcpu_is_populated(chunk, bit_off, bits, + &next_off)) + break; + + bit_off = next_off; + bits = 0; + } + + if (bit_off == pcpu_chunk_map_bits(chunk)) + return -1; + + return bit_off; +} + +/** + * pcpu_alloc_area - allocates an area from a pcpu_chunk + * @chunk: chunk of interest + * @alloc_bits: size of request in allocation units + * @align: alignment of area (max PAGE_SIZE) + * @start: bit_off to start searching + * + * This function takes in a @start offset to begin searching to fit an + * allocation of @alloc_bits with alignment @align. It needs to scan + * the allocation map because if it fits within the block's contig hint, + * @start will be block->first_free. This is an attempt to fill the + * allocation prior to breaking the contig hint. The allocation and + * boundary maps are updated accordingly if it confirms a valid + * free area. + * + * RETURNS: + * Allocated addr offset in @chunk on success. + * -1 if no matching area is found. + */ +static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits, + size_t align, int start) +{ + size_t align_mask = (align) ? (align - 1) : 0; + int bit_off, end, oslot; + + lockdep_assert_held(&pcpu_lock); + + oslot = pcpu_chunk_slot(chunk); + + /* + * Search to find a fit. + */ + end = min_t(int, start + alloc_bits + PCPU_BITMAP_BLOCK_BITS, + pcpu_chunk_map_bits(chunk)); + bit_off = bitmap_find_next_zero_area(chunk->alloc_map, end, start, + alloc_bits, align_mask); + if (bit_off >= end) + return -1; + + /* update alloc map */ + bitmap_set(chunk->alloc_map, bit_off, alloc_bits); + + /* update boundary map */ + set_bit(bit_off, chunk->bound_map); + bitmap_clear(chunk->bound_map, bit_off + 1, alloc_bits - 1); + set_bit(bit_off + alloc_bits, chunk->bound_map); + + chunk->free_bytes -= alloc_bits * PCPU_MIN_ALLOC_SIZE; + + /* update first free bit */ + if (bit_off == chunk->first_bit) + chunk->first_bit = find_next_zero_bit( + chunk->alloc_map, + pcpu_chunk_map_bits(chunk), + bit_off + alloc_bits); + + pcpu_block_update_hint_alloc(chunk, bit_off, alloc_bits); + + pcpu_chunk_relocate(chunk, oslot); + + return bit_off * PCPU_MIN_ALLOC_SIZE; +} + +/** + * pcpu_free_area - frees the corresponding offset + * @chunk: chunk of interest + * @off: addr offset into chunk + * + * This function determines the size of an allocation to free using + * the boundary bitmap and clears the allocation map. + */ +static void pcpu_free_area(struct pcpu_chunk *chunk, int off) +{ + int bit_off, bits, end, oslot; + + lockdep_assert_held(&pcpu_lock); + pcpu_stats_area_dealloc(chunk); + + oslot = pcpu_chunk_slot(chunk); + + bit_off = off / PCPU_MIN_ALLOC_SIZE; + + /* find end index */ + end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk), + bit_off + 1); + bits = end - bit_off; + bitmap_clear(chunk->alloc_map, bit_off, bits); + + /* update metadata */ + chunk->free_bytes += bits * PCPU_MIN_ALLOC_SIZE; + + /* update first free bit */ + chunk->first_bit = min(chunk->first_bit, bit_off); + + pcpu_block_update_hint_free(chunk, bit_off, bits); + + pcpu_chunk_relocate(chunk, oslot); +} + +static void pcpu_init_md_blocks(struct pcpu_chunk *chunk) +{ + struct pcpu_block_md *md_block; + + for (md_block = chunk->md_blocks; + md_block != chunk->md_blocks + pcpu_chunk_nr_blocks(chunk); + md_block++) { + md_block->contig_hint = PCPU_BITMAP_BLOCK_BITS; + md_block->left_free = PCPU_BITMAP_BLOCK_BITS; + md_block->right_free = PCPU_BITMAP_BLOCK_BITS; + } +} + +/** + * pcpu_alloc_first_chunk - creates chunks that serve the first chunk + * @tmp_addr: the start of the region served + * @map_size: size of the region served + * + * This is responsible for creating the chunks that serve the first chunk. The + * base_addr is page aligned down of @tmp_addr while the region end is page + * aligned up. Offsets are kept track of to determine the region served. All + * this is done to appease the bitmap allocator in avoiding partial blocks. + * + * RETURNS: + * Chunk serving the region at @tmp_addr of @map_size. + */ +static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr, + int map_size) +{ + struct pcpu_chunk *chunk; + unsigned long aligned_addr, lcm_align; + int start_offset, offset_bits, region_size, region_bits; + + /* region calculations */ + aligned_addr = tmp_addr & PAGE_MASK; + + start_offset = tmp_addr - aligned_addr; + + /* + * Align the end of the region with the LCM of PAGE_SIZE and + * PCPU_BITMAP_BLOCK_SIZE. One of these constants is a multiple of + * the other. + */ + lcm_align = lcm(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE); + region_size = ALIGN(start_offset + map_size, lcm_align); + + /* allocate chunk */ + chunk = memblock_virt_alloc(sizeof(struct pcpu_chunk) + + BITS_TO_LONGS(region_size >> PAGE_SHIFT) * sizeof(unsigned long), + 0); + + INIT_LIST_HEAD(&chunk->list); + + chunk->base_addr = (void *)aligned_addr; + chunk->start_offset = start_offset; + chunk->end_offset = region_size - chunk->start_offset - map_size; + + chunk->nr_pages = region_size >> PAGE_SHIFT; + region_bits = pcpu_chunk_map_bits(chunk); + + chunk->alloc_map = memblock_virt_alloc(BITS_TO_LONGS(region_bits) * + sizeof(chunk->alloc_map[0]), 0); + chunk->bound_map = memblock_virt_alloc(BITS_TO_LONGS(region_bits + 1) * + sizeof(chunk->bound_map[0]), 0); + chunk->md_blocks = memblock_virt_alloc(pcpu_chunk_nr_blocks(chunk) * + sizeof(chunk->md_blocks[0]), 0); + pcpu_init_md_blocks(chunk); + + /* manage populated page bitmap */ + chunk->immutable = true; + bitmap_fill(chunk->populated, chunk->nr_pages); + chunk->nr_populated = chunk->nr_pages; + chunk->nr_empty_pop_pages = + pcpu_cnt_pop_pages(chunk, start_offset / PCPU_MIN_ALLOC_SIZE, + map_size / PCPU_MIN_ALLOC_SIZE); + + chunk->contig_bits = map_size / PCPU_MIN_ALLOC_SIZE; + chunk->free_bytes = map_size; + + if (chunk->start_offset) { + /* hide the beginning of the bitmap */ + offset_bits = chunk->start_offset / PCPU_MIN_ALLOC_SIZE; + bitmap_set(chunk->alloc_map, 0, offset_bits); + set_bit(0, chunk->bound_map); + set_bit(offset_bits, chunk->bound_map); + + chunk->first_bit = offset_bits; + + pcpu_block_update_hint_alloc(chunk, 0, offset_bits); + } + + if (chunk->end_offset) { + /* hide the end of the bitmap */ + offset_bits = chunk->end_offset / PCPU_MIN_ALLOC_SIZE; + bitmap_set(chunk->alloc_map, + pcpu_chunk_map_bits(chunk) - offset_bits, + offset_bits); + set_bit((start_offset + map_size) / PCPU_MIN_ALLOC_SIZE, + chunk->bound_map); + set_bit(region_bits, chunk->bound_map); + + pcpu_block_update_hint_alloc(chunk, pcpu_chunk_map_bits(chunk) + - offset_bits, offset_bits); + } + + return chunk; +} + +static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t gfp) +{ + struct pcpu_chunk *chunk; + int region_bits; + + chunk = pcpu_mem_zalloc(pcpu_chunk_struct_size, gfp); + if (!chunk) + return NULL; + + INIT_LIST_HEAD(&chunk->list); + chunk->nr_pages = pcpu_unit_pages; + region_bits = pcpu_chunk_map_bits(chunk); + + chunk->alloc_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits) * + sizeof(chunk->alloc_map[0]), gfp); + if (!chunk->alloc_map) + goto alloc_map_fail; + + chunk->bound_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits + 1) * + sizeof(chunk->bound_map[0]), gfp); + if (!chunk->bound_map) + goto bound_map_fail; + + chunk->md_blocks = pcpu_mem_zalloc(pcpu_chunk_nr_blocks(chunk) * + sizeof(chunk->md_blocks[0]), gfp); + if (!chunk->md_blocks) + goto md_blocks_fail; + + pcpu_init_md_blocks(chunk); + + /* init metadata */ + chunk->contig_bits = region_bits; + chunk->free_bytes = chunk->nr_pages * PAGE_SIZE; + + return chunk; + +md_blocks_fail: + pcpu_mem_free(chunk->bound_map); +bound_map_fail: + pcpu_mem_free(chunk->alloc_map); +alloc_map_fail: + pcpu_mem_free(chunk); + + return NULL; +} + +static void pcpu_free_chunk(struct pcpu_chunk *chunk) +{ + if (!chunk) + return; + pcpu_mem_free(chunk->md_blocks); + pcpu_mem_free(chunk->bound_map); + pcpu_mem_free(chunk->alloc_map); + pcpu_mem_free(chunk); +} + +/** + * pcpu_chunk_populated - post-population bookkeeping + * @chunk: pcpu_chunk which got populated + * @page_start: the start page + * @page_end: the end page + * @for_alloc: if this is to populate for allocation + * + * Pages in [@page_start,@page_end) have been populated to @chunk. Update + * the bookkeeping information accordingly. Must be called after each + * successful population. + * + * If this is @for_alloc, do not increment pcpu_nr_empty_pop_pages because it + * is to serve an allocation in that area. + */ +static void pcpu_chunk_populated(struct pcpu_chunk *chunk, int page_start, + int page_end, bool for_alloc) +{ + int nr = page_end - page_start; + + lockdep_assert_held(&pcpu_lock); + + bitmap_set(chunk->populated, page_start, nr); + chunk->nr_populated += nr; + pcpu_nr_populated += nr; + + if (!for_alloc) { + chunk->nr_empty_pop_pages += nr; + pcpu_nr_empty_pop_pages += nr; + } +} + +/** + * pcpu_chunk_depopulated - post-depopulation bookkeeping + * @chunk: pcpu_chunk which got depopulated + * @page_start: the start page + * @page_end: the end page + * + * Pages in [@page_start,@page_end) have been depopulated from @chunk. + * Update the bookkeeping information accordingly. Must be called after + * each successful depopulation. + */ +static void pcpu_chunk_depopulated(struct pcpu_chunk *chunk, + int page_start, int page_end) +{ + int nr = page_end - page_start; + + lockdep_assert_held(&pcpu_lock); + + bitmap_clear(chunk->populated, page_start, nr); + chunk->nr_populated -= nr; + chunk->nr_empty_pop_pages -= nr; + pcpu_nr_empty_pop_pages -= nr; + pcpu_nr_populated -= nr; +} + +/* + * Chunk management implementation. + * + * To allow different implementations, chunk alloc/free and + * [de]population are implemented in a separate file which is pulled + * into this file and compiled together. The following functions + * should be implemented. + * + * pcpu_populate_chunk - populate the specified range of a chunk + * pcpu_depopulate_chunk - depopulate the specified range of a chunk + * pcpu_create_chunk - create a new chunk + * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop + * pcpu_addr_to_page - translate address to physical address + * pcpu_verify_alloc_info - check alloc_info is acceptable during init + */ +static int pcpu_populate_chunk(struct pcpu_chunk *chunk, + int page_start, int page_end, gfp_t gfp); +static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, + int page_start, int page_end); +static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp); +static void pcpu_destroy_chunk(struct pcpu_chunk *chunk); +static struct page *pcpu_addr_to_page(void *addr); +static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai); + +#ifdef CONFIG_NEED_PER_CPU_KM +#include "percpu-km.c" +#else +#include "percpu-vm.c" +#endif + +/** + * pcpu_chunk_addr_search - determine chunk containing specified address + * @addr: address for which the chunk needs to be determined. + * + * This is an internal function that handles all but static allocations. + * Static percpu address values should never be passed into the allocator. + * + * RETURNS: + * The address of the found chunk. + */ +static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr) +{ + /* is it in the dynamic region (first chunk)? */ + if (pcpu_addr_in_chunk(pcpu_first_chunk, addr)) + return pcpu_first_chunk; + + /* is it in the reserved region? */ + if (pcpu_addr_in_chunk(pcpu_reserved_chunk, addr)) + return pcpu_reserved_chunk; + + /* + * The address is relative to unit0 which might be unused and + * thus unmapped. Offset the address to the unit space of the + * current processor before looking it up in the vmalloc + * space. Note that any possible cpu id can be used here, so + * there's no need to worry about preemption or cpu hotplug. + */ + addr += pcpu_unit_offsets[raw_smp_processor_id()]; + return pcpu_get_page_chunk(pcpu_addr_to_page(addr)); +} + +/** + * pcpu_alloc - the percpu allocator + * @size: size of area to allocate in bytes + * @align: alignment of area (max PAGE_SIZE) + * @reserved: allocate from the reserved chunk if available + * @gfp: allocation flags + * + * Allocate percpu area of @size bytes aligned at @align. If @gfp doesn't + * contain %GFP_KERNEL, the allocation is atomic. If @gfp has __GFP_NOWARN + * then no warning will be triggered on invalid or failed allocation + * requests. + * + * RETURNS: + * Percpu pointer to the allocated area on success, NULL on failure. + */ +static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved, + gfp_t gfp) +{ + /* whitelisted flags that can be passed to the backing allocators */ + gfp_t pcpu_gfp = gfp & (GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN); + bool is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL; + bool do_warn = !(gfp & __GFP_NOWARN); + static int warn_limit = 10; + struct pcpu_chunk *chunk; + const char *err; + int slot, off, cpu, ret; + unsigned long flags; + void __percpu *ptr; + size_t bits, bit_align; + + /* + * There is now a minimum allocation size of PCPU_MIN_ALLOC_SIZE, + * therefore alignment must be a minimum of that many bytes. + * An allocation may have internal fragmentation from rounding up + * of up to PCPU_MIN_ALLOC_SIZE - 1 bytes. + */ + if (unlikely(align < PCPU_MIN_ALLOC_SIZE)) + align = PCPU_MIN_ALLOC_SIZE; + + size = ALIGN(size, PCPU_MIN_ALLOC_SIZE); + bits = size >> PCPU_MIN_ALLOC_SHIFT; + bit_align = align >> PCPU_MIN_ALLOC_SHIFT; + + if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE || + !is_power_of_2(align))) { + WARN(do_warn, "illegal size (%zu) or align (%zu) for percpu allocation\n", + size, align); + return NULL; + } + + if (!is_atomic) { + /* + * pcpu_balance_workfn() allocates memory under this mutex, + * and it may wait for memory reclaim. Allow current task + * to become OOM victim, in case of memory pressure. + */ + if (gfp & __GFP_NOFAIL) + mutex_lock(&pcpu_alloc_mutex); + else if (mutex_lock_killable(&pcpu_alloc_mutex)) + return NULL; + } + + spin_lock_irqsave(&pcpu_lock, flags); + + /* serve reserved allocations from the reserved chunk if available */ + if (reserved && pcpu_reserved_chunk) { + chunk = pcpu_reserved_chunk; + + off = pcpu_find_block_fit(chunk, bits, bit_align, is_atomic); + if (off < 0) { + err = "alloc from reserved chunk failed"; + goto fail_unlock; + } + + off = pcpu_alloc_area(chunk, bits, bit_align, off); + if (off >= 0) + goto area_found; + + err = "alloc from reserved chunk failed"; + goto fail_unlock; + } + +restart: + /* search through normal chunks */ + for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) { + list_for_each_entry(chunk, &pcpu_slot[slot], list) { + off = pcpu_find_block_fit(chunk, bits, bit_align, + is_atomic); + if (off < 0) + continue; + + off = pcpu_alloc_area(chunk, bits, bit_align, off); + if (off >= 0) + goto area_found; + + } + } + + spin_unlock_irqrestore(&pcpu_lock, flags); + + /* + * No space left. Create a new chunk. We don't want multiple + * tasks to create chunks simultaneously. Serialize and create iff + * there's still no empty chunk after grabbing the mutex. + */ + if (is_atomic) { + err = "atomic alloc failed, no space left"; + goto fail; + } + + if (list_empty(&pcpu_slot[pcpu_nr_slots - 1])) { + chunk = pcpu_create_chunk(pcpu_gfp); + if (!chunk) { + err = "failed to allocate new chunk"; + goto fail; + } + + spin_lock_irqsave(&pcpu_lock, flags); + pcpu_chunk_relocate(chunk, -1); + } else { + spin_lock_irqsave(&pcpu_lock, flags); + } + + goto restart; + +area_found: + pcpu_stats_area_alloc(chunk, size); + spin_unlock_irqrestore(&pcpu_lock, flags); + + /* populate if not all pages are already there */ + if (!is_atomic) { + int page_start, page_end, rs, re; + + page_start = PFN_DOWN(off); + page_end = PFN_UP(off + size); + + pcpu_for_each_unpop_region(chunk->populated, rs, re, + page_start, page_end) { + WARN_ON(chunk->immutable); + + ret = pcpu_populate_chunk(chunk, rs, re, pcpu_gfp); + + spin_lock_irqsave(&pcpu_lock, flags); + if (ret) { + pcpu_free_area(chunk, off); + err = "failed to populate"; + goto fail_unlock; + } + pcpu_chunk_populated(chunk, rs, re, true); + spin_unlock_irqrestore(&pcpu_lock, flags); + } + + mutex_unlock(&pcpu_alloc_mutex); + } + + if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW) + pcpu_schedule_balance_work(); + + /* clear the areas and return address relative to base address */ + for_each_possible_cpu(cpu) + memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size); + + ptr = __addr_to_pcpu_ptr(chunk->base_addr + off); + kmemleak_alloc_percpu(ptr, size, gfp); + + trace_percpu_alloc_percpu(reserved, is_atomic, size, align, + chunk->base_addr, off, ptr); + + return ptr; + +fail_unlock: + spin_unlock_irqrestore(&pcpu_lock, flags); +fail: + trace_percpu_alloc_percpu_fail(reserved, is_atomic, size, align); + + if (!is_atomic && do_warn && warn_limit) { + pr_warn("allocation failed, size=%zu align=%zu atomic=%d, %s\n", + size, align, is_atomic, err); + dump_stack(); + if (!--warn_limit) + pr_info("limit reached, disable warning\n"); + } + if (is_atomic) { + /* see the flag handling in pcpu_blance_workfn() */ + pcpu_atomic_alloc_failed = true; + pcpu_schedule_balance_work(); + } else { + mutex_unlock(&pcpu_alloc_mutex); + } + return NULL; +} + +/** + * __alloc_percpu_gfp - allocate dynamic percpu area + * @size: size of area to allocate in bytes + * @align: alignment of area (max PAGE_SIZE) + * @gfp: allocation flags + * + * Allocate zero-filled percpu area of @size bytes aligned at @align. If + * @gfp doesn't contain %GFP_KERNEL, the allocation doesn't block and can + * be called from any context but is a lot more likely to fail. If @gfp + * has __GFP_NOWARN then no warning will be triggered on invalid or failed + * allocation requests. + * + * RETURNS: + * Percpu pointer to the allocated area on success, NULL on failure. + */ +void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp) +{ + return pcpu_alloc(size, align, false, gfp); +} +EXPORT_SYMBOL_GPL(__alloc_percpu_gfp); + +/** + * __alloc_percpu - allocate dynamic percpu area + * @size: size of area to allocate in bytes + * @align: alignment of area (max PAGE_SIZE) + * + * Equivalent to __alloc_percpu_gfp(size, align, %GFP_KERNEL). + */ +void __percpu *__alloc_percpu(size_t size, size_t align) +{ + return pcpu_alloc(size, align, false, GFP_KERNEL); +} +EXPORT_SYMBOL_GPL(__alloc_percpu); + +/** + * __alloc_reserved_percpu - allocate reserved percpu area + * @size: size of area to allocate in bytes + * @align: alignment of area (max PAGE_SIZE) + * + * Allocate zero-filled percpu area of @size bytes aligned at @align + * from reserved percpu area if arch has set it up; otherwise, + * allocation is served from the same dynamic area. Might sleep. + * Might trigger writeouts. + * + * CONTEXT: + * Does GFP_KERNEL allocation. + * + * RETURNS: + * Percpu pointer to the allocated area on success, NULL on failure. + */ +void __percpu *__alloc_reserved_percpu(size_t size, size_t align) +{ + return pcpu_alloc(size, align, true, GFP_KERNEL); +} + +/** + * pcpu_balance_workfn - manage the amount of free chunks and populated pages + * @work: unused + * + * Reclaim all fully free chunks except for the first one. This is also + * responsible for maintaining the pool of empty populated pages. However, + * it is possible that this is called when physical memory is scarce causing + * OOM killer to be triggered. We should avoid doing so until an actual + * allocation causes the failure as it is possible that requests can be + * serviced from already backed regions. + */ +static void pcpu_balance_workfn(struct work_struct *work) +{ + /* gfp flags passed to underlying allocators */ + const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN; + LIST_HEAD(to_free); + struct list_head *free_head = &pcpu_slot[pcpu_nr_slots - 1]; + struct pcpu_chunk *chunk, *next; + int slot, nr_to_pop, ret; + + /* + * There's no reason to keep around multiple unused chunks and VM + * areas can be scarce. Destroy all free chunks except for one. + */ + mutex_lock(&pcpu_alloc_mutex); + spin_lock_irq(&pcpu_lock); + + list_for_each_entry_safe(chunk, next, free_head, list) { + WARN_ON(chunk->immutable); + + /* spare the first one */ + if (chunk == list_first_entry(free_head, struct pcpu_chunk, list)) + continue; + + list_move(&chunk->list, &to_free); + } + + spin_unlock_irq(&pcpu_lock); + + list_for_each_entry_safe(chunk, next, &to_free, list) { + int rs, re; + + pcpu_for_each_pop_region(chunk->populated, rs, re, 0, + chunk->nr_pages) { + pcpu_depopulate_chunk(chunk, rs, re); + spin_lock_irq(&pcpu_lock); + pcpu_chunk_depopulated(chunk, rs, re); + spin_unlock_irq(&pcpu_lock); + } + pcpu_destroy_chunk(chunk); + cond_resched(); + } + + /* + * Ensure there are certain number of free populated pages for + * atomic allocs. Fill up from the most packed so that atomic + * allocs don't increase fragmentation. If atomic allocation + * failed previously, always populate the maximum amount. This + * should prevent atomic allocs larger than PAGE_SIZE from keeping + * failing indefinitely; however, large atomic allocs are not + * something we support properly and can be highly unreliable and + * inefficient. + */ +retry_pop: + if (pcpu_atomic_alloc_failed) { + nr_to_pop = PCPU_EMPTY_POP_PAGES_HIGH; + /* best effort anyway, don't worry about synchronization */ + pcpu_atomic_alloc_failed = false; + } else { + nr_to_pop = clamp(PCPU_EMPTY_POP_PAGES_HIGH - + pcpu_nr_empty_pop_pages, + 0, PCPU_EMPTY_POP_PAGES_HIGH); + } + + for (slot = pcpu_size_to_slot(PAGE_SIZE); slot < pcpu_nr_slots; slot++) { + int nr_unpop = 0, rs, re; + + if (!nr_to_pop) + break; + + spin_lock_irq(&pcpu_lock); + list_for_each_entry(chunk, &pcpu_slot[slot], list) { + nr_unpop = chunk->nr_pages - chunk->nr_populated; + if (nr_unpop) + break; + } + spin_unlock_irq(&pcpu_lock); + + if (!nr_unpop) + continue; + + /* @chunk can't go away while pcpu_alloc_mutex is held */ + pcpu_for_each_unpop_region(chunk->populated, rs, re, 0, + chunk->nr_pages) { + int nr = min(re - rs, nr_to_pop); + + ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp); + if (!ret) { + nr_to_pop -= nr; + spin_lock_irq(&pcpu_lock); + pcpu_chunk_populated(chunk, rs, rs + nr, false); + spin_unlock_irq(&pcpu_lock); + } else { + nr_to_pop = 0; + } + + if (!nr_to_pop) + break; + } + } + + if (nr_to_pop) { + /* ran out of chunks to populate, create a new one and retry */ + chunk = pcpu_create_chunk(gfp); + if (chunk) { + spin_lock_irq(&pcpu_lock); + pcpu_chunk_relocate(chunk, -1); + spin_unlock_irq(&pcpu_lock); + goto retry_pop; + } + } + + mutex_unlock(&pcpu_alloc_mutex); +} + +/** + * free_percpu - free percpu area + * @ptr: pointer to area to free + * + * Free percpu area @ptr. + * + * CONTEXT: + * Can be called from atomic context. + */ +void free_percpu(void __percpu *ptr) +{ + void *addr; + struct pcpu_chunk *chunk; + unsigned long flags; + int off; + bool need_balance = false; + + if (!ptr) + return; + + kmemleak_free_percpu(ptr); + + addr = __pcpu_ptr_to_addr(ptr); + + spin_lock_irqsave(&pcpu_lock, flags); + + chunk = pcpu_chunk_addr_search(addr); + off = addr - chunk->base_addr; + + pcpu_free_area(chunk, off); + + /* if there are more than one fully free chunks, wake up grim reaper */ + if (chunk->free_bytes == pcpu_unit_size) { + struct pcpu_chunk *pos; + + list_for_each_entry(pos, &pcpu_slot[pcpu_nr_slots - 1], list) + if (pos != chunk) { + need_balance = true; + break; + } + } + + trace_percpu_free_percpu(chunk->base_addr, off, ptr); + + spin_unlock_irqrestore(&pcpu_lock, flags); + + if (need_balance) + pcpu_schedule_balance_work(); +} +EXPORT_SYMBOL_GPL(free_percpu); + +bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr) +{ +#ifdef CONFIG_SMP + const size_t static_size = __per_cpu_end - __per_cpu_start; + void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr); + unsigned int cpu; + + for_each_possible_cpu(cpu) { + void *start = per_cpu_ptr(base, cpu); + void *va = (void *)addr; + + if (va >= start && va < start + static_size) { + if (can_addr) { + *can_addr = (unsigned long) (va - start); + *can_addr += (unsigned long) + per_cpu_ptr(base, get_boot_cpu_id()); + } + return true; + } + } +#endif + /* on UP, can't distinguish from other static vars, always false */ + return false; +} + +/** + * is_kernel_percpu_address - test whether address is from static percpu area + * @addr: address to test + * + * Test whether @addr belongs to in-kernel static percpu area. Module + * static percpu areas are not considered. For those, use + * is_module_percpu_address(). + * + * RETURNS: + * %true if @addr is from in-kernel static percpu area, %false otherwise. + */ +bool is_kernel_percpu_address(unsigned long addr) +{ + return __is_kernel_percpu_address(addr, NULL); +} + +/** + * per_cpu_ptr_to_phys - convert translated percpu address to physical address + * @addr: the address to be converted to physical address + * + * Given @addr which is dereferenceable address obtained via one of + * percpu access macros, this function translates it into its physical + * address. The caller is responsible for ensuring @addr stays valid + * until this function finishes. + * + * percpu allocator has special setup for the first chunk, which currently + * supports either embedding in linear address space or vmalloc mapping, + * and, from the second one, the backing allocator (currently either vm or + * km) provides translation. + * + * The addr can be translated simply without checking if it falls into the + * first chunk. But the current code reflects better how percpu allocator + * actually works, and the verification can discover both bugs in percpu + * allocator itself and per_cpu_ptr_to_phys() callers. So we keep current + * code. + * + * RETURNS: + * The physical address for @addr. + */ +phys_addr_t per_cpu_ptr_to_phys(void *addr) +{ + void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr); + bool in_first_chunk = false; + unsigned long first_low, first_high; + unsigned int cpu; + + /* + * The following test on unit_low/high isn't strictly + * necessary but will speed up lookups of addresses which + * aren't in the first chunk. + * + * The address check is against full chunk sizes. pcpu_base_addr + * points to the beginning of the first chunk including the + * static region. Assumes good intent as the first chunk may + * not be full (ie. < pcpu_unit_pages in size). + */ + first_low = (unsigned long)pcpu_base_addr + + pcpu_unit_page_offset(pcpu_low_unit_cpu, 0); + first_high = (unsigned long)pcpu_base_addr + + pcpu_unit_page_offset(pcpu_high_unit_cpu, pcpu_unit_pages); + if ((unsigned long)addr >= first_low && + (unsigned long)addr < first_high) { + for_each_possible_cpu(cpu) { + void *start = per_cpu_ptr(base, cpu); + + if (addr >= start && addr < start + pcpu_unit_size) { + in_first_chunk = true; + break; + } + } + } + + if (in_first_chunk) { + if (!is_vmalloc_addr(addr)) + return __pa(addr); + else + return page_to_phys(vmalloc_to_page(addr)) + + offset_in_page(addr); + } else + return page_to_phys(pcpu_addr_to_page(addr)) + + offset_in_page(addr); +} + +/** + * pcpu_alloc_alloc_info - allocate percpu allocation info + * @nr_groups: the number of groups + * @nr_units: the number of units + * + * Allocate ai which is large enough for @nr_groups groups containing + * @nr_units units. The returned ai's groups[0].cpu_map points to the + * cpu_map array which is long enough for @nr_units and filled with + * NR_CPUS. It's the caller's responsibility to initialize cpu_map + * pointer of other groups. + * + * RETURNS: + * Pointer to the allocated pcpu_alloc_info on success, NULL on + * failure. + */ +struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups, + int nr_units) +{ + struct pcpu_alloc_info *ai; + size_t base_size, ai_size; + void *ptr; + int unit; + + base_size = ALIGN(sizeof(*ai) + nr_groups * sizeof(ai->groups[0]), + __alignof__(ai->groups[0].cpu_map[0])); + ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]); + + ptr = memblock_virt_alloc_nopanic(PFN_ALIGN(ai_size), PAGE_SIZE); + if (!ptr) + return NULL; + ai = ptr; + ptr += base_size; + + ai->groups[0].cpu_map = ptr; + + for (unit = 0; unit < nr_units; unit++) + ai->groups[0].cpu_map[unit] = NR_CPUS; + + ai->nr_groups = nr_groups; + ai->__ai_size = PFN_ALIGN(ai_size); + + return ai; +} + +/** + * pcpu_free_alloc_info - free percpu allocation info + * @ai: pcpu_alloc_info to free + * + * Free @ai which was allocated by pcpu_alloc_alloc_info(). + */ +void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai) +{ + memblock_free_early(__pa(ai), ai->__ai_size); +} + +/** + * pcpu_dump_alloc_info - print out information about pcpu_alloc_info + * @lvl: loglevel + * @ai: allocation info to dump + * + * Print out information about @ai using loglevel @lvl. + */ +static void pcpu_dump_alloc_info(const char *lvl, + const struct pcpu_alloc_info *ai) +{ + int group_width = 1, cpu_width = 1, width; + char empty_str[] = "--------"; + int alloc = 0, alloc_end = 0; + int group, v; + int upa, apl; /* units per alloc, allocs per line */ + + v = ai->nr_groups; + while (v /= 10) + group_width++; + + v = num_possible_cpus(); + while (v /= 10) + cpu_width++; + empty_str[min_t(int, cpu_width, sizeof(empty_str) - 1)] = '\0'; + + upa = ai->alloc_size / ai->unit_size; + width = upa * (cpu_width + 1) + group_width + 3; + apl = rounddown_pow_of_two(max(60 / width, 1)); + + printk("%spcpu-alloc: s%zu r%zu d%zu u%zu alloc=%zu*%zu", + lvl, ai->static_size, ai->reserved_size, ai->dyn_size, + ai->unit_size, ai->alloc_size / ai->atom_size, ai->atom_size); + + for (group = 0; group < ai->nr_groups; group++) { + const struct pcpu_group_info *gi = &ai->groups[group]; + int unit = 0, unit_end = 0; + + BUG_ON(gi->nr_units % upa); + for (alloc_end += gi->nr_units / upa; + alloc < alloc_end; alloc++) { + if (!(alloc % apl)) { + pr_cont("\n"); + printk("%spcpu-alloc: ", lvl); + } + pr_cont("[%0*d] ", group_width, group); + + for (unit_end += upa; unit < unit_end; unit++) + if (gi->cpu_map[unit] != NR_CPUS) + pr_cont("%0*d ", + cpu_width, gi->cpu_map[unit]); + else + pr_cont("%s ", empty_str); + } + } + pr_cont("\n"); +} + +/** + * pcpu_setup_first_chunk - initialize the first percpu chunk + * @ai: pcpu_alloc_info describing how to percpu area is shaped + * @base_addr: mapped address + * + * Initialize the first percpu chunk which contains the kernel static + * perpcu area. This function is to be called from arch percpu area + * setup path. + * + * @ai contains all information necessary to initialize the first + * chunk and prime the dynamic percpu allocator. + * + * @ai->static_size is the size of static percpu area. + * + * @ai->reserved_size, if non-zero, specifies the amount of bytes to + * reserve after the static area in the first chunk. This reserves + * the first chunk such that it's available only through reserved + * percpu allocation. This is primarily used to serve module percpu + * static areas on architectures where the addressing model has + * limited offset range for symbol relocations to guarantee module + * percpu symbols fall inside the relocatable range. + * + * @ai->dyn_size determines the number of bytes available for dynamic + * allocation in the first chunk. The area between @ai->static_size + + * @ai->reserved_size + @ai->dyn_size and @ai->unit_size is unused. + * + * @ai->unit_size specifies unit size and must be aligned to PAGE_SIZE + * and equal to or larger than @ai->static_size + @ai->reserved_size + + * @ai->dyn_size. + * + * @ai->atom_size is the allocation atom size and used as alignment + * for vm areas. + * + * @ai->alloc_size is the allocation size and always multiple of + * @ai->atom_size. This is larger than @ai->atom_size if + * @ai->unit_size is larger than @ai->atom_size. + * + * @ai->nr_groups and @ai->groups describe virtual memory layout of + * percpu areas. Units which should be colocated are put into the + * same group. Dynamic VM areas will be allocated according to these + * groupings. If @ai->nr_groups is zero, a single group containing + * all units is assumed. + * + * The caller should have mapped the first chunk at @base_addr and + * copied static data to each unit. + * + * The first chunk will always contain a static and a dynamic region. + * However, the static region is not managed by any chunk. If the first + * chunk also contains a reserved region, it is served by two chunks - + * one for the reserved region and one for the dynamic region. They + * share the same vm, but use offset regions in the area allocation map. + * The chunk serving the dynamic region is circulated in the chunk slots + * and available for dynamic allocation like any other chunk. + * + * RETURNS: + * 0 on success, -errno on failure. + */ +int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai, + void *base_addr) +{ + size_t size_sum = ai->static_size + ai->reserved_size + ai->dyn_size; + size_t static_size, dyn_size; + struct pcpu_chunk *chunk; + unsigned long *group_offsets; + size_t *group_sizes; + unsigned long *unit_off; + unsigned int cpu; + int *unit_map; + int group, unit, i; + int map_size; + unsigned long tmp_addr; + +#define PCPU_SETUP_BUG_ON(cond) do { \ + if (unlikely(cond)) { \ + pr_emerg("failed to initialize, %s\n", #cond); \ + pr_emerg("cpu_possible_mask=%*pb\n", \ + cpumask_pr_args(cpu_possible_mask)); \ + pcpu_dump_alloc_info(KERN_EMERG, ai); \ + BUG(); \ + } \ +} while (0) + + /* sanity checks */ + PCPU_SETUP_BUG_ON(ai->nr_groups <= 0); +#ifdef CONFIG_SMP + PCPU_SETUP_BUG_ON(!ai->static_size); + PCPU_SETUP_BUG_ON(offset_in_page(__per_cpu_start)); +#endif + PCPU_SETUP_BUG_ON(!base_addr); + PCPU_SETUP_BUG_ON(offset_in_page(base_addr)); + PCPU_SETUP_BUG_ON(ai->unit_size < size_sum); + PCPU_SETUP_BUG_ON(offset_in_page(ai->unit_size)); + PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE); + PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->unit_size, PCPU_BITMAP_BLOCK_SIZE)); + PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE); + PCPU_SETUP_BUG_ON(!ai->dyn_size); + PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->reserved_size, PCPU_MIN_ALLOC_SIZE)); + PCPU_SETUP_BUG_ON(!(IS_ALIGNED(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) || + IS_ALIGNED(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE))); + PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0); + + /* process group information and build config tables accordingly */ + group_offsets = memblock_virt_alloc(ai->nr_groups * + sizeof(group_offsets[0]), 0); + group_sizes = memblock_virt_alloc(ai->nr_groups * + sizeof(group_sizes[0]), 0); + unit_map = memblock_virt_alloc(nr_cpu_ids * sizeof(unit_map[0]), 0); + unit_off = memblock_virt_alloc(nr_cpu_ids * sizeof(unit_off[0]), 0); + + for (cpu = 0; cpu < nr_cpu_ids; cpu++) + unit_map[cpu] = UINT_MAX; + + pcpu_low_unit_cpu = NR_CPUS; + pcpu_high_unit_cpu = NR_CPUS; + + for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) { + const struct pcpu_group_info *gi = &ai->groups[group]; + + group_offsets[group] = gi->base_offset; + group_sizes[group] = gi->nr_units * ai->unit_size; + + for (i = 0; i < gi->nr_units; i++) { + cpu = gi->cpu_map[i]; + if (cpu == NR_CPUS) + continue; + + PCPU_SETUP_BUG_ON(cpu >= nr_cpu_ids); + PCPU_SETUP_BUG_ON(!cpu_possible(cpu)); + PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX); + + unit_map[cpu] = unit + i; + unit_off[cpu] = gi->base_offset + i * ai->unit_size; + + /* determine low/high unit_cpu */ + if (pcpu_low_unit_cpu == NR_CPUS || + unit_off[cpu] < unit_off[pcpu_low_unit_cpu]) + pcpu_low_unit_cpu = cpu; + if (pcpu_high_unit_cpu == NR_CPUS || + unit_off[cpu] > unit_off[pcpu_high_unit_cpu]) + pcpu_high_unit_cpu = cpu; + } + } + pcpu_nr_units = unit; + + for_each_possible_cpu(cpu) + PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX); + + /* we're done parsing the input, undefine BUG macro and dump config */ +#undef PCPU_SETUP_BUG_ON + pcpu_dump_alloc_info(KERN_DEBUG, ai); + + pcpu_nr_groups = ai->nr_groups; + pcpu_group_offsets = group_offsets; + pcpu_group_sizes = group_sizes; + pcpu_unit_map = unit_map; + pcpu_unit_offsets = unit_off; + + /* determine basic parameters */ + pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT; + pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT; + pcpu_atom_size = ai->atom_size; + pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) + + BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long); + + pcpu_stats_save_ai(ai); + + /* + * Allocate chunk slots. The additional last slot is for + * empty chunks. + */ + pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2; + pcpu_slot = memblock_virt_alloc( + pcpu_nr_slots * sizeof(pcpu_slot[0]), 0); + for (i = 0; i < pcpu_nr_slots; i++) + INIT_LIST_HEAD(&pcpu_slot[i]); + + /* + * The end of the static region needs to be aligned with the + * minimum allocation size as this offsets the reserved and + * dynamic region. The first chunk ends page aligned by + * expanding the dynamic region, therefore the dynamic region + * can be shrunk to compensate while still staying above the + * configured sizes. + */ + static_size = ALIGN(ai->static_size, PCPU_MIN_ALLOC_SIZE); + dyn_size = ai->dyn_size - (static_size - ai->static_size); + + /* + * Initialize first chunk. + * If the reserved_size is non-zero, this initializes the reserved + * chunk. If the reserved_size is zero, the reserved chunk is NULL + * and the dynamic region is initialized here. The first chunk, + * pcpu_first_chunk, will always point to the chunk that serves + * the dynamic region. + */ + tmp_addr = (unsigned long)base_addr + static_size; + map_size = ai->reserved_size ?: dyn_size; + chunk = pcpu_alloc_first_chunk(tmp_addr, map_size); + + /* init dynamic chunk if necessary */ + if (ai->reserved_size) { + pcpu_reserved_chunk = chunk; + + tmp_addr = (unsigned long)base_addr + static_size + + ai->reserved_size; + map_size = dyn_size; + chunk = pcpu_alloc_first_chunk(tmp_addr, map_size); + } + + /* link the first chunk in */ + pcpu_first_chunk = chunk; + pcpu_nr_empty_pop_pages = pcpu_first_chunk->nr_empty_pop_pages; + pcpu_chunk_relocate(pcpu_first_chunk, -1); + + /* include all regions of the first chunk */ + pcpu_nr_populated += PFN_DOWN(size_sum); + + pcpu_stats_chunk_alloc(); + trace_percpu_create_chunk(base_addr); + + /* we're done */ + pcpu_base_addr = base_addr; + return 0; +} + +#ifdef CONFIG_SMP + +const char * const pcpu_fc_names[PCPU_FC_NR] __initconst = { + [PCPU_FC_AUTO] = "auto", + [PCPU_FC_EMBED] = "embed", + [PCPU_FC_PAGE] = "page", +}; + +enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO; + +static int __init percpu_alloc_setup(char *str) +{ + if (!str) + return -EINVAL; + + if (0) + /* nada */; +#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK + else if (!strcmp(str, "embed")) + pcpu_chosen_fc = PCPU_FC_EMBED; +#endif +#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK + else if (!strcmp(str, "page")) + pcpu_chosen_fc = PCPU_FC_PAGE; +#endif + else + pr_warn("unknown allocator %s specified\n", str); + + return 0; +} +early_param("percpu_alloc", percpu_alloc_setup); + +/* + * pcpu_embed_first_chunk() is used by the generic percpu setup. + * Build it if needed by the arch config or the generic setup is going + * to be used. + */ +#if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \ + !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA) +#define BUILD_EMBED_FIRST_CHUNK +#endif + +/* build pcpu_page_first_chunk() iff needed by the arch config */ +#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) +#define BUILD_PAGE_FIRST_CHUNK +#endif + +/* pcpu_build_alloc_info() is used by both embed and page first chunk */ +#if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK) +/** + * pcpu_build_alloc_info - build alloc_info considering distances between CPUs + * @reserved_size: the size of reserved percpu area in bytes + * @dyn_size: minimum free size for dynamic allocation in bytes + * @atom_size: allocation atom size + * @cpu_distance_fn: callback to determine distance between cpus, optional + * + * This function determines grouping of units, their mappings to cpus + * and other parameters considering needed percpu size, allocation + * atom size and distances between CPUs. + * + * Groups are always multiples of atom size and CPUs which are of + * LOCAL_DISTANCE both ways are grouped together and share space for + * units in the same group. The returned configuration is guaranteed + * to have CPUs on different nodes on different groups and >=75% usage + * of allocated virtual address space. + * + * RETURNS: + * On success, pointer to the new allocation_info is returned. On + * failure, ERR_PTR value is returned. + */ +static struct pcpu_alloc_info * __init pcpu_build_alloc_info( + size_t reserved_size, size_t dyn_size, + size_t atom_size, + pcpu_fc_cpu_distance_fn_t cpu_distance_fn) +{ + static int group_map[NR_CPUS] __initdata; + static int group_cnt[NR_CPUS] __initdata; + const size_t static_size = __per_cpu_end - __per_cpu_start; + int nr_groups = 1, nr_units = 0; + size_t size_sum, min_unit_size, alloc_size; + int upa, max_upa, uninitialized_var(best_upa); /* units_per_alloc */ + int last_allocs, group, unit; + unsigned int cpu, tcpu; + struct pcpu_alloc_info *ai; + unsigned int *cpu_map; + + /* this function may be called multiple times */ + memset(group_map, 0, sizeof(group_map)); + memset(group_cnt, 0, sizeof(group_cnt)); + + /* calculate size_sum and ensure dyn_size is enough for early alloc */ + size_sum = PFN_ALIGN(static_size + reserved_size + + max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE)); + dyn_size = size_sum - static_size - reserved_size; + + /* + * Determine min_unit_size, alloc_size and max_upa such that + * alloc_size is multiple of atom_size and is the smallest + * which can accommodate 4k aligned segments which are equal to + * or larger than min_unit_size. + */ + min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE); + + /* determine the maximum # of units that can fit in an allocation */ + alloc_size = roundup(min_unit_size, atom_size); + upa = alloc_size / min_unit_size; + while (alloc_size % upa || (offset_in_page(alloc_size / upa))) + upa--; + max_upa = upa; + + /* group cpus according to their proximity */ + for_each_possible_cpu(cpu) { + group = 0; + next_group: + for_each_possible_cpu(tcpu) { + if (cpu == tcpu) + break; + if (group_map[tcpu] == group && cpu_distance_fn && + (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE || + cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) { + group++; + nr_groups = max(nr_groups, group + 1); + goto next_group; + } + } + group_map[cpu] = group; + group_cnt[group]++; + } + + /* + * Wasted space is caused by a ratio imbalance of upa to group_cnt. + * Expand the unit_size until we use >= 75% of the units allocated. + * Related to atom_size, which could be much larger than the unit_size. + */ + last_allocs = INT_MAX; + for (upa = max_upa; upa; upa--) { + int allocs = 0, wasted = 0; + + if (alloc_size % upa || (offset_in_page(alloc_size / upa))) + continue; + + for (group = 0; group < nr_groups; group++) { + int this_allocs = DIV_ROUND_UP(group_cnt[group], upa); + allocs += this_allocs; + wasted += this_allocs * upa - group_cnt[group]; + } + + /* + * Don't accept if wastage is over 1/3. The + * greater-than comparison ensures upa==1 always + * passes the following check. + */ + if (wasted > num_possible_cpus() / 3) + continue; + + /* and then don't consume more memory */ + if (allocs > last_allocs) + break; + last_allocs = allocs; + best_upa = upa; + } + upa = best_upa; + + /* allocate and fill alloc_info */ + for (group = 0; group < nr_groups; group++) + nr_units += roundup(group_cnt[group], upa); + + ai = pcpu_alloc_alloc_info(nr_groups, nr_units); + if (!ai) + return ERR_PTR(-ENOMEM); + cpu_map = ai->groups[0].cpu_map; + + for (group = 0; group < nr_groups; group++) { + ai->groups[group].cpu_map = cpu_map; + cpu_map += roundup(group_cnt[group], upa); + } + + ai->static_size = static_size; + ai->reserved_size = reserved_size; + ai->dyn_size = dyn_size; + ai->unit_size = alloc_size / upa; + ai->atom_size = atom_size; + ai->alloc_size = alloc_size; + + for (group = 0, unit = 0; group_cnt[group]; group++) { + struct pcpu_group_info *gi = &ai->groups[group]; + + /* + * Initialize base_offset as if all groups are located + * back-to-back. The caller should update this to + * reflect actual allocation. + */ + gi->base_offset = unit * ai->unit_size; + + for_each_possible_cpu(cpu) + if (group_map[cpu] == group) + gi->cpu_map[gi->nr_units++] = cpu; + gi->nr_units = roundup(gi->nr_units, upa); + unit += gi->nr_units; + } + BUG_ON(unit != nr_units); + + return ai; +} +#endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */ + +#if defined(BUILD_EMBED_FIRST_CHUNK) +/** + * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem + * @reserved_size: the size of reserved percpu area in bytes + * @dyn_size: minimum free size for dynamic allocation in bytes + * @atom_size: allocation atom size + * @cpu_distance_fn: callback to determine distance between cpus, optional + * @alloc_fn: function to allocate percpu page + * @free_fn: function to free percpu page + * + * This is a helper to ease setting up embedded first percpu chunk and + * can be called where pcpu_setup_first_chunk() is expected. + * + * If this function is used to setup the first chunk, it is allocated + * by calling @alloc_fn and used as-is without being mapped into + * vmalloc area. Allocations are always whole multiples of @atom_size + * aligned to @atom_size. + * + * This enables the first chunk to piggy back on the linear physical + * mapping which often uses larger page size. Please note that this + * can result in very sparse cpu->unit mapping on NUMA machines thus + * requiring large vmalloc address space. Don't use this allocator if + * vmalloc space is not orders of magnitude larger than distances + * between node memory addresses (ie. 32bit NUMA machines). + * + * @dyn_size specifies the minimum dynamic area size. + * + * If the needed size is smaller than the minimum or specified unit + * size, the leftover is returned using @free_fn. + * + * RETURNS: + * 0 on success, -errno on failure. + */ +int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size, + size_t atom_size, + pcpu_fc_cpu_distance_fn_t cpu_distance_fn, + pcpu_fc_alloc_fn_t alloc_fn, + pcpu_fc_free_fn_t free_fn) +{ + void *base = (void *)ULONG_MAX; + void **areas = NULL; + struct pcpu_alloc_info *ai; + size_t size_sum, areas_size; + unsigned long max_distance; + int group, i, highest_group, rc; + + ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size, + cpu_distance_fn); + if (IS_ERR(ai)) + return PTR_ERR(ai); + + size_sum = ai->static_size + ai->reserved_size + ai->dyn_size; + areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *)); + + areas = memblock_virt_alloc_nopanic(areas_size, 0); + if (!areas) { + rc = -ENOMEM; + goto out_free; + } + + /* allocate, copy and determine base address & max_distance */ + highest_group = 0; + for (group = 0; group < ai->nr_groups; group++) { + struct pcpu_group_info *gi = &ai->groups[group]; + unsigned int cpu = NR_CPUS; + void *ptr; + + for (i = 0; i < gi->nr_units && cpu == NR_CPUS; i++) + cpu = gi->cpu_map[i]; + BUG_ON(cpu == NR_CPUS); + + /* allocate space for the whole group */ + ptr = alloc_fn(cpu, gi->nr_units * ai->unit_size, atom_size); + if (!ptr) { + rc = -ENOMEM; + goto out_free_areas; + } + /* kmemleak tracks the percpu allocations separately */ + kmemleak_free(ptr); + areas[group] = ptr; + + base = min(ptr, base); + if (ptr > areas[highest_group]) + highest_group = group; + } + max_distance = areas[highest_group] - base; + max_distance += ai->unit_size * ai->groups[highest_group].nr_units; + + /* warn if maximum distance is further than 75% of vmalloc space */ + if (max_distance > VMALLOC_TOTAL * 3 / 4) { + pr_warn("max_distance=0x%lx too large for vmalloc space 0x%lx\n", + max_distance, VMALLOC_TOTAL); +#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK + /* and fail if we have fallback */ + rc = -EINVAL; + goto out_free_areas; +#endif + } + + /* + * Copy data and free unused parts. This should happen after all + * allocations are complete; otherwise, we may end up with + * overlapping groups. + */ + for (group = 0; group < ai->nr_groups; group++) { + struct pcpu_group_info *gi = &ai->groups[group]; + void *ptr = areas[group]; + + for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) { + if (gi->cpu_map[i] == NR_CPUS) { + /* unused unit, free whole */ + free_fn(ptr, ai->unit_size); + continue; + } + /* copy and return the unused part */ + memcpy(ptr, __per_cpu_load, ai->static_size); + free_fn(ptr + size_sum, ai->unit_size - size_sum); + } + } + + /* base address is now known, determine group base offsets */ + for (group = 0; group < ai->nr_groups; group++) { + ai->groups[group].base_offset = areas[group] - base; + } + + pr_info("Embedded %zu pages/cpu s%zu r%zu d%zu u%zu\n", + PFN_DOWN(size_sum), ai->static_size, ai->reserved_size, + ai->dyn_size, ai->unit_size); + + rc = pcpu_setup_first_chunk(ai, base); + goto out_free; + +out_free_areas: + for (group = 0; group < ai->nr_groups; group++) + if (areas[group]) + free_fn(areas[group], + ai->groups[group].nr_units * ai->unit_size); +out_free: + pcpu_free_alloc_info(ai); + if (areas) + memblock_free_early(__pa(areas), areas_size); + return rc; +} +#endif /* BUILD_EMBED_FIRST_CHUNK */ + +#ifdef BUILD_PAGE_FIRST_CHUNK +/** + * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages + * @reserved_size: the size of reserved percpu area in bytes + * @alloc_fn: function to allocate percpu page, always called with PAGE_SIZE + * @free_fn: function to free percpu page, always called with PAGE_SIZE + * @populate_pte_fn: function to populate pte + * + * This is a helper to ease setting up page-remapped first percpu + * chunk and can be called where pcpu_setup_first_chunk() is expected. + * + * This is the basic allocator. Static percpu area is allocated + * page-by-page into vmalloc area. + * + * RETURNS: + * 0 on success, -errno on failure. + */ +int __init pcpu_page_first_chunk(size_t reserved_size, + pcpu_fc_alloc_fn_t alloc_fn, + pcpu_fc_free_fn_t free_fn, + pcpu_fc_populate_pte_fn_t populate_pte_fn) +{ + static struct vm_struct vm; + struct pcpu_alloc_info *ai; + char psize_str[16]; + int unit_pages; + size_t pages_size; + struct page **pages; + int unit, i, j, rc; + int upa; + int nr_g0_units; + + snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10); + + ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL); + if (IS_ERR(ai)) + return PTR_ERR(ai); + BUG_ON(ai->nr_groups != 1); + upa = ai->alloc_size/ai->unit_size; + nr_g0_units = roundup(num_possible_cpus(), upa); + if (unlikely(WARN_ON(ai->groups[0].nr_units != nr_g0_units))) { + pcpu_free_alloc_info(ai); + return -EINVAL; + } + + unit_pages = ai->unit_size >> PAGE_SHIFT; + + /* unaligned allocations can't be freed, round up to page size */ + pages_size = PFN_ALIGN(unit_pages * num_possible_cpus() * + sizeof(pages[0])); + pages = memblock_virt_alloc(pages_size, 0); + + /* allocate pages */ + j = 0; + for (unit = 0; unit < num_possible_cpus(); unit++) { + unsigned int cpu = ai->groups[0].cpu_map[unit]; + for (i = 0; i < unit_pages; i++) { + void *ptr; + + ptr = alloc_fn(cpu, PAGE_SIZE, PAGE_SIZE); + if (!ptr) { + pr_warn("failed to allocate %s page for cpu%u\n", + psize_str, cpu); + goto enomem; + } + /* kmemleak tracks the percpu allocations separately */ + kmemleak_free(ptr); + pages[j++] = virt_to_page(ptr); + } + } + + /* allocate vm area, map the pages and copy static data */ + vm.flags = VM_ALLOC; + vm.size = num_possible_cpus() * ai->unit_size; + vm_area_register_early(&vm, PAGE_SIZE); + + for (unit = 0; unit < num_possible_cpus(); unit++) { + unsigned long unit_addr = + (unsigned long)vm.addr + unit * ai->unit_size; + + for (i = 0; i < unit_pages; i++) + populate_pte_fn(unit_addr + (i << PAGE_SHIFT)); + + /* pte already populated, the following shouldn't fail */ + rc = __pcpu_map_pages(unit_addr, &pages[unit * unit_pages], + unit_pages); + if (rc < 0) + panic("failed to map percpu area, err=%d\n", rc); + + /* + * FIXME: Archs with virtual cache should flush local + * cache for the linear mapping here - something + * equivalent to flush_cache_vmap() on the local cpu. + * flush_cache_vmap() can't be used as most supporting + * data structures are not set up yet. + */ + + /* copy static data */ + memcpy((void *)unit_addr, __per_cpu_load, ai->static_size); + } + + /* we're ready, commit */ + pr_info("%d %s pages/cpu s%zu r%zu d%zu\n", + unit_pages, psize_str, ai->static_size, + ai->reserved_size, ai->dyn_size); + + rc = pcpu_setup_first_chunk(ai, vm.addr); + goto out_free_ar; + +enomem: + while (--j >= 0) + free_fn(page_address(pages[j]), PAGE_SIZE); + rc = -ENOMEM; +out_free_ar: + memblock_free_early(__pa(pages), pages_size); + pcpu_free_alloc_info(ai); + return rc; +} +#endif /* BUILD_PAGE_FIRST_CHUNK */ + +#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA +/* + * Generic SMP percpu area setup. + * + * The embedding helper is used because its behavior closely resembles + * the original non-dynamic generic percpu area setup. This is + * important because many archs have addressing restrictions and might + * fail if the percpu area is located far away from the previous + * location. As an added bonus, in non-NUMA cases, embedding is + * generally a good idea TLB-wise because percpu area can piggy back + * on the physical linear memory mapping which uses large page + * mappings on applicable archs. + */ +unsigned long __per_cpu_offset[NR_CPUS] __read_mostly; +EXPORT_SYMBOL(__per_cpu_offset); + +static void * __init pcpu_dfl_fc_alloc(unsigned int cpu, size_t size, + size_t align) +{ + return memblock_virt_alloc_from_nopanic( + size, align, __pa(MAX_DMA_ADDRESS)); +} + +static void __init pcpu_dfl_fc_free(void *ptr, size_t size) +{ + memblock_free_early(__pa(ptr), size); +} + +void __init setup_per_cpu_areas(void) +{ + unsigned long delta; + unsigned int cpu; + int rc; + + /* + * Always reserve area for module percpu variables. That's + * what the legacy allocator did. + */ + rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE, + PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL, + pcpu_dfl_fc_alloc, pcpu_dfl_fc_free); + if (rc < 0) + panic("Failed to initialize percpu areas."); + + delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start; + for_each_possible_cpu(cpu) + __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu]; +} +#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */ + +#else /* CONFIG_SMP */ + +/* + * UP percpu area setup. + * + * UP always uses km-based percpu allocator with identity mapping. + * Static percpu variables are indistinguishable from the usual static + * variables and don't require any special preparation. + */ +void __init setup_per_cpu_areas(void) +{ + const size_t unit_size = + roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE, + PERCPU_DYNAMIC_RESERVE)); + struct pcpu_alloc_info *ai; + void *fc; + + ai = pcpu_alloc_alloc_info(1, 1); + fc = memblock_virt_alloc_from_nopanic(unit_size, + PAGE_SIZE, + __pa(MAX_DMA_ADDRESS)); + if (!ai || !fc) + panic("Failed to allocate memory for percpu areas."); + /* kmemleak tracks the percpu allocations separately */ + kmemleak_free(fc); + + ai->dyn_size = unit_size; + ai->unit_size = unit_size; + ai->atom_size = unit_size; + ai->alloc_size = unit_size; + ai->groups[0].nr_units = 1; + ai->groups[0].cpu_map[0] = 0; + + if (pcpu_setup_first_chunk(ai, fc) < 0) + panic("Failed to initialize percpu areas."); + pcpu_free_alloc_info(ai); +} + +#endif /* CONFIG_SMP */ + +/* + * pcpu_nr_pages - calculate total number of populated backing pages + * + * This reflects the number of pages populated to back chunks. Metadata is + * excluded in the number exposed in meminfo as the number of backing pages + * scales with the number of cpus and can quickly outweigh the memory used for + * metadata. It also keeps this calculation nice and simple. + * + * RETURNS: + * Total number of populated backing pages in use by the allocator. + */ +unsigned long pcpu_nr_pages(void) +{ + return pcpu_nr_populated * pcpu_nr_units; +} + +/* + * Percpu allocator is initialized early during boot when neither slab or + * workqueue is available. Plug async management until everything is up + * and running. + */ +static int __init percpu_enable_async(void) +{ + pcpu_async_enabled = true; + return 0; +} +subsys_initcall(percpu_enable_async); |