| /* |
| * linux/mm/percpu.c - percpu memory allocator |
| * |
| * Copyright (C) 2009 SUSE Linux Products GmbH |
| * Copyright (C) 2009 Tejun Heo <tj@kernel.org> |
| * |
| * This file is released under the GPLv2. |
| * |
| * This is percpu allocator which can handle both static and dynamic |
| * areas. Percpu areas are allocated in chunks in vmalloc area. Each |
| * chunk is consisted of num_possible_cpus() units and the first chunk |
| * is used for static percpu variables in the kernel image (special |
| * boot time alloc/init handling necessary as these areas need to be |
| * brought up before allocation services are running). Unit grows as |
| * necessary and all units grow or shrink in unison. When a chunk is |
| * filled up, another chunk is allocated. ie. in vmalloc area |
| * |
| * c0 c1 c2 |
| * ------------------- ------------------- ------------ |
| * | u0 | u1 | u2 | u3 | | u0 | u1 | u2 | u3 | | u0 | u1 | u |
| * ------------------- ...... ------------------- .... ------------ |
| * |
| * Allocation is done in offset-size areas of single unit space. Ie, |
| * an area of 512 bytes at 6k in c1 occupies 512 bytes at 6k of c1:u0, |
| * c1:u1, c1:u2 and c1:u3. Percpu access can be done by configuring |
| * percpu base registers UNIT_SIZE apart. |
| * |
| * There are usually many small percpu allocations many of them as |
| * small as 4 bytes. The allocator organizes chunks into lists |
| * according to free size and tries to allocate from the fullest one. |
| * Each chunk keeps the maximum contiguous area size hint which is |
| * guaranteed to be eqaul to or larger than the maximum contiguous |
| * area in the chunk. This helps the allocator not to iterate the |
| * chunk maps unnecessarily. |
| * |
| * Allocation state in each chunk is kept using an array of integers |
| * on chunk->map. A positive value in the map represents a free |
| * region and negative allocated. Allocation inside a chunk is done |
| * by scanning this map sequentially and serving the first matching |
| * entry. This is mostly copied from the percpu_modalloc() allocator. |
| * Chunks are also linked into a rb tree to ease address to chunk |
| * mapping during free. |
| * |
| * To use this allocator, arch code should do the followings. |
| * |
| * - define CONFIG_HAVE_DYNAMIC_PER_CPU_AREA |
| * |
| * - 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 |
| */ |
| |
| #include <linux/bitmap.h> |
| #include <linux/bootmem.h> |
| #include <linux/list.h> |
| #include <linux/mm.h> |
| #include <linux/module.h> |
| #include <linux/mutex.h> |
| #include <linux/percpu.h> |
| #include <linux/pfn.h> |
| #include <linux/rbtree.h> |
| #include <linux/slab.h> |
| #include <linux/spinlock.h> |
| #include <linux/vmalloc.h> |
| #include <linux/workqueue.h> |
| |
| #include <asm/cacheflush.h> |
| #include <asm/sections.h> |
| #include <asm/tlbflush.h> |
| |
| #define PCPU_SLOT_BASE_SHIFT 5 /* 1-31 shares the same slot */ |
| #define PCPU_DFL_MAP_ALLOC 16 /* start a map with 16 ents */ |
| |
| /* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */ |
| #ifndef __addr_to_pcpu_ptr |
| #define __addr_to_pcpu_ptr(addr) \ |
| (void *)((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 *)((unsigned long)(ptr) + (unsigned long)pcpu_base_addr \ |
| - (unsigned long)__per_cpu_start) |
| #endif |
| |
| struct pcpu_chunk { |
| struct list_head list; /* linked to pcpu_slot lists */ |
| struct rb_node rb_node; /* key is chunk->vm->addr */ |
| int free_size; /* free bytes in the chunk */ |
| int contig_hint; /* max contiguous size hint */ |
| struct vm_struct *vm; /* mapped vmalloc region */ |
| int map_used; /* # of map entries used */ |
| int map_alloc; /* # of map entries allocated */ |
| int *map; /* allocation map */ |
| bool immutable; /* no [de]population allowed */ |
| struct page **page; /* points to page array */ |
| struct page *page_ar[]; /* #cpus * UNIT_PAGES */ |
| }; |
| |
| static int pcpu_unit_pages __read_mostly; |
| static int pcpu_unit_size __read_mostly; |
| static int pcpu_chunk_size __read_mostly; |
| static int pcpu_nr_slots __read_mostly; |
| static size_t pcpu_chunk_struct_size __read_mostly; |
| |
| /* the address of the first chunk which starts with the kernel static area */ |
| void *pcpu_base_addr __read_mostly; |
| EXPORT_SYMBOL_GPL(pcpu_base_addr); |
| |
| /* optional reserved chunk, only accessible for reserved allocations */ |
| static struct pcpu_chunk *pcpu_reserved_chunk; |
| /* offset limit of the reserved chunk */ |
| static int pcpu_reserved_chunk_limit; |
| |
| /* |
| * Synchronization rules. |
| * |
| * There are two locks - pcpu_alloc_mutex and pcpu_lock. The former |
| * protects allocation/reclaim paths, chunks and chunk->page arrays. |
| * The latter is a spinlock and protects the index data structures - |
| * chunk slots, rbtree, chunks and area maps in chunks. |
| * |
| * During allocation, pcpu_alloc_mutex is kept locked all the time and |
| * pcpu_lock is grabbed and released as necessary. All actual memory |
| * allocations are done using GFP_KERNEL with pcpu_lock released. |
| * |
| * Free path accesses and alters only the index data structures, so it |
| * can be safely called from atomic context. When memory needs to be |
| * returned to the system, free path schedules reclaim_work which |
| * grabs both pcpu_alloc_mutex and pcpu_lock, unlinks chunks to be |
| * reclaimed, release both locks and frees the chunks. Note that it's |
| * necessary to grab both locks to remove a chunk from circulation as |
| * allocation path might be referencing the chunk with only |
| * pcpu_alloc_mutex locked. |
| */ |
| static DEFINE_MUTEX(pcpu_alloc_mutex); /* protects whole alloc and reclaim */ |
| static DEFINE_SPINLOCK(pcpu_lock); /* protects index data structures */ |
| |
| static struct list_head *pcpu_slot __read_mostly; /* chunk list slots */ |
| static struct rb_root pcpu_addr_root = RB_ROOT; /* chunks by address */ |
| |
| /* reclaim work to release fully free chunks, scheduled from free path */ |
| static void pcpu_reclaim(struct work_struct *work); |
| static DECLARE_WORK(pcpu_reclaim_work, pcpu_reclaim); |
| |
| 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_size < sizeof(int) || chunk->contig_hint < sizeof(int)) |
| return 0; |
| |
| return pcpu_size_to_slot(chunk->free_size); |
| } |
| |
| static int pcpu_page_idx(unsigned int cpu, int page_idx) |
| { |
| return cpu * pcpu_unit_pages + page_idx; |
| } |
| |
| static struct page **pcpu_chunk_pagep(struct pcpu_chunk *chunk, |
| unsigned int cpu, int page_idx) |
| { |
| return &chunk->page[pcpu_page_idx(cpu, page_idx)]; |
| } |
| |
| static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk, |
| unsigned int cpu, int page_idx) |
| { |
| return (unsigned long)chunk->vm->addr + |
| (pcpu_page_idx(cpu, page_idx) << PAGE_SHIFT); |
| } |
| |
| static bool pcpu_chunk_page_occupied(struct pcpu_chunk *chunk, |
| int page_idx) |
| { |
| return *pcpu_chunk_pagep(chunk, 0, page_idx) != NULL; |
| } |
| |
| /** |
| * pcpu_mem_alloc - allocate memory |
| * @size: bytes to allocate |
| * |
| * Allocate @size bytes. If @size is smaller than PAGE_SIZE, |
| * kzalloc() is used; otherwise, vmalloc() is used. The returned |
| * memory is always zeroed. |
| * |
| * CONTEXT: |
| * Does GFP_KERNEL allocation. |
| * |
| * RETURNS: |
| * Pointer to the allocated area on success, NULL on failure. |
| */ |
| static void *pcpu_mem_alloc(size_t size) |
| { |
| if (size <= PAGE_SIZE) |
| return kzalloc(size, GFP_KERNEL); |
| else { |
| void *ptr = vmalloc(size); |
| if (ptr) |
| memset(ptr, 0, size); |
| return ptr; |
| } |
| } |
| |
| /** |
| * pcpu_mem_free - free memory |
| * @ptr: memory to free |
| * @size: size of the area |
| * |
| * Free @ptr. @ptr should have been allocated using pcpu_mem_alloc(). |
| */ |
| static void pcpu_mem_free(void *ptr, size_t size) |
| { |
| if (size <= PAGE_SIZE) |
| kfree(ptr); |
| else |
| vfree(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]); |
| } |
| } |
| |
| static struct rb_node **pcpu_chunk_rb_search(void *addr, |
| struct rb_node **parentp) |
| { |
| struct rb_node **p = &pcpu_addr_root.rb_node; |
| struct rb_node *parent = NULL; |
| struct pcpu_chunk *chunk; |
| |
| while (*p) { |
| parent = *p; |
| chunk = rb_entry(parent, struct pcpu_chunk, rb_node); |
| |
| if (addr < chunk->vm->addr) |
| p = &(*p)->rb_left; |
| else if (addr > chunk->vm->addr) |
| p = &(*p)->rb_right; |
| else |
| break; |
| } |
| |
| if (parentp) |
| *parentp = parent; |
| return p; |
| } |
| |
| /** |
| * pcpu_chunk_addr_search - search for chunk containing specified address |
| * @addr: address to search for |
| * |
| * Look for chunk which might contain @addr. More specifically, it |
| * searchs for the chunk with the highest start address which isn't |
| * beyond @addr. |
| * |
| * CONTEXT: |
| * pcpu_lock. |
| * |
| * RETURNS: |
| * The address of the found chunk. |
| */ |
| static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr) |
| { |
| struct rb_node *n, *parent; |
| struct pcpu_chunk *chunk; |
| |
| /* is it in the reserved chunk? */ |
| if (pcpu_reserved_chunk) { |
| void *start = pcpu_reserved_chunk->vm->addr; |
| |
| if (addr >= start && addr < start + pcpu_reserved_chunk_limit) |
| return pcpu_reserved_chunk; |
| } |
| |
| /* nah... search the regular ones */ |
| n = *pcpu_chunk_rb_search(addr, &parent); |
| if (!n) { |
| /* no exactly matching chunk, the parent is the closest */ |
| n = parent; |
| BUG_ON(!n); |
| } |
| chunk = rb_entry(n, struct pcpu_chunk, rb_node); |
| |
| if (addr < chunk->vm->addr) { |
| /* the parent was the next one, look for the previous one */ |
| n = rb_prev(n); |
| BUG_ON(!n); |
| chunk = rb_entry(n, struct pcpu_chunk, rb_node); |
| } |
| |
| return chunk; |
| } |
| |
| /** |
| * pcpu_chunk_addr_insert - insert chunk into address rb tree |
| * @new: chunk to insert |
| * |
| * Insert @new into address rb tree. |
| * |
| * CONTEXT: |
| * pcpu_lock. |
| */ |
| static void pcpu_chunk_addr_insert(struct pcpu_chunk *new) |
| { |
| struct rb_node **p, *parent; |
| |
| p = pcpu_chunk_rb_search(new->vm->addr, &parent); |
| BUG_ON(*p); |
| rb_link_node(&new->rb_node, parent, p); |
| rb_insert_color(&new->rb_node, &pcpu_addr_root); |
| } |
| |
| /** |
| * pcpu_extend_area_map - extend area map for allocation |
| * @chunk: target chunk |
| * |
| * Extend area map of @chunk so that it can accomodate an allocation. |
| * A single allocation can split an area into three areas, so this |
| * function makes sure that @chunk->map has at least two extra slots. |
| * |
| * CONTEXT: |
| * pcpu_alloc_mutex, pcpu_lock. pcpu_lock is released and reacquired |
| * if area map is extended. |
| * |
| * RETURNS: |
| * 0 if noop, 1 if successfully extended, -errno on failure. |
| */ |
| static int pcpu_extend_area_map(struct pcpu_chunk *chunk) |
| { |
| int new_alloc; |
| int *new; |
| size_t size; |
| |
| /* has enough? */ |
| if (chunk->map_alloc >= chunk->map_used + 2) |
| return 0; |
| |
| spin_unlock_irq(&pcpu_lock); |
| |
| new_alloc = PCPU_DFL_MAP_ALLOC; |
| while (new_alloc < chunk->map_used + 2) |
| new_alloc *= 2; |
| |
| new = pcpu_mem_alloc(new_alloc * sizeof(new[0])); |
| if (!new) { |
| spin_lock_irq(&pcpu_lock); |
| return -ENOMEM; |
| } |
| |
| /* |
| * Acquire pcpu_lock and switch to new area map. Only free |
| * could have happened inbetween, so map_used couldn't have |
| * grown. |
| */ |
| spin_lock_irq(&pcpu_lock); |
| BUG_ON(new_alloc < chunk->map_used + 2); |
| |
| size = chunk->map_alloc * sizeof(chunk->map[0]); |
| memcpy(new, chunk->map, size); |
| |
| /* |
| * map_alloc < PCPU_DFL_MAP_ALLOC indicates that the chunk is |
| * one of the first chunks and still using static map. |
| */ |
| if (chunk->map_alloc >= PCPU_DFL_MAP_ALLOC) |
| pcpu_mem_free(chunk->map, size); |
| |
| chunk->map_alloc = new_alloc; |
| chunk->map = new; |
| return 0; |
| } |
| |
| /** |
| * pcpu_split_block - split a map block |
| * @chunk: chunk of interest |
| * @i: index of map block to split |
| * @head: head size in bytes (can be 0) |
| * @tail: tail size in bytes (can be 0) |
| * |
| * Split the @i'th map block into two or three blocks. If @head is |
| * non-zero, @head bytes block is inserted before block @i moving it |
| * to @i+1 and reducing its size by @head bytes. |
| * |
| * If @tail is non-zero, the target block, which can be @i or @i+1 |
| * depending on @head, is reduced by @tail bytes and @tail byte block |
| * is inserted after the target block. |
| * |
| * @chunk->map must have enough free slots to accomodate the split. |
| * |
| * CONTEXT: |
| * pcpu_lock. |
| */ |
| static void pcpu_split_block(struct pcpu_chunk *chunk, int i, |
| int head, int tail) |
| { |
| int nr_extra = !!head + !!tail; |
| |
| BUG_ON(chunk->map_alloc < chunk->map_used + nr_extra); |
| |
| /* insert new subblocks */ |
| memmove(&chunk->map[i + nr_extra], &chunk->map[i], |
| sizeof(chunk->map[0]) * (chunk->map_used - i)); |
| chunk->map_used += nr_extra; |
| |
| if (head) { |
| chunk->map[i + 1] = chunk->map[i] - head; |
| chunk->map[i++] = head; |
| } |
| if (tail) { |
| chunk->map[i++] -= tail; |
| chunk->map[i] = tail; |
| } |
| } |
| |
| /** |
| * pcpu_alloc_area - allocate area from a pcpu_chunk |
| * @chunk: chunk of interest |
| * @size: wanted size in bytes |
| * @align: wanted align |
| * |
| * Try to allocate @size bytes area aligned at @align from @chunk. |
| * Note that this function only allocates the offset. It doesn't |
| * populate or map the area. |
| * |
| * @chunk->map must have at least two free slots. |
| * |
| * CONTEXT: |
| * pcpu_lock. |
| * |
| * RETURNS: |
| * Allocated offset in @chunk on success, -1 if no matching area is |
| * found. |
| */ |
| static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align) |
| { |
| int oslot = pcpu_chunk_slot(chunk); |
| int max_contig = 0; |
| int i, off; |
| |
| for (i = 0, off = 0; i < chunk->map_used; off += abs(chunk->map[i++])) { |
| bool is_last = i + 1 == chunk->map_used; |
| int head, tail; |
| |
| /* extra for alignment requirement */ |
| head = ALIGN(off, align) - off; |
| BUG_ON(i == 0 && head != 0); |
| |
| if (chunk->map[i] < 0) |
| continue; |
| if (chunk->map[i] < head + size) { |
| max_contig = max(chunk->map[i], max_contig); |
| continue; |
| } |
| |
| /* |
| * If head is small or the previous block is free, |
| * merge'em. Note that 'small' is defined as smaller |
| * than sizeof(int), which is very small but isn't too |
| * uncommon for percpu allocations. |
| */ |
| if (head && (head < sizeof(int) || chunk->map[i - 1] > 0)) { |
| if (chunk->map[i - 1] > 0) |
| chunk->map[i - 1] += head; |
| else { |
| chunk->map[i - 1] -= head; |
| chunk->free_size -= head; |
| } |
| chunk->map[i] -= head; |
| off += head; |
| head = 0; |
| } |
| |
| /* if tail is small, just keep it around */ |
| tail = chunk->map[i] - head - size; |
| if (tail < sizeof(int)) |
| tail = 0; |
| |
| /* split if warranted */ |
| if (head || tail) { |
| pcpu_split_block(chunk, i, head, tail); |
| if (head) { |
| i++; |
| off += head; |
| max_contig = max(chunk->map[i - 1], max_contig); |
| } |
| if (tail) |
| max_contig = max(chunk->map[i + 1], max_contig); |
| } |
| |
| /* update hint and mark allocated */ |
| if (is_last) |
| chunk->contig_hint = max_contig; /* fully scanned */ |
| else |
| chunk->contig_hint = max(chunk->contig_hint, |
| max_contig); |
| |
| chunk->free_size -= chunk->map[i]; |
| chunk->map[i] = -chunk->map[i]; |
| |
| pcpu_chunk_relocate(chunk, oslot); |
| return off; |
| } |
| |
| chunk->contig_hint = max_contig; /* fully scanned */ |
| pcpu_chunk_relocate(chunk, oslot); |
| |
| /* tell the upper layer that this chunk has no matching area */ |
| return -1; |
| } |
| |
| /** |
| * pcpu_free_area - free area to a pcpu_chunk |
| * @chunk: chunk of interest |
| * @freeme: offset of area to free |
| * |
| * Free area starting from @freeme to @chunk. Note that this function |
| * only modifies the allocation map. It doesn't depopulate or unmap |
| * the area. |
| * |
| * CONTEXT: |
| * pcpu_lock. |
| */ |
| static void pcpu_free_area(struct pcpu_chunk *chunk, int freeme) |
| { |
| int oslot = pcpu_chunk_slot(chunk); |
| int i, off; |
| |
| for (i = 0, off = 0; i < chunk->map_used; off += abs(chunk->map[i++])) |
| if (off == freeme) |
| break; |
| BUG_ON(off != freeme); |
| BUG_ON(chunk->map[i] > 0); |
| |
| chunk->map[i] = -chunk->map[i]; |
| chunk->free_size += chunk->map[i]; |
| |
| /* merge with previous? */ |
| if (i > 0 && chunk->map[i - 1] >= 0) { |
| chunk->map[i - 1] += chunk->map[i]; |
| chunk->map_used--; |
| memmove(&chunk->map[i], &chunk->map[i + 1], |
| (chunk->map_used - i) * sizeof(chunk->map[0])); |
| i--; |
| } |
| /* merge with next? */ |
| if (i + 1 < chunk->map_used && chunk->map[i + 1] >= 0) { |
| chunk->map[i] += chunk->map[i + 1]; |
| chunk->map_used--; |
| memmove(&chunk->map[i + 1], &chunk->map[i + 2], |
| (chunk->map_used - (i + 1)) * sizeof(chunk->map[0])); |
| } |
| |
| chunk->contig_hint = max(chunk->map[i], chunk->contig_hint); |
| pcpu_chunk_relocate(chunk, oslot); |
| } |
| |
| /** |
| * pcpu_unmap - unmap pages out of a pcpu_chunk |
| * @chunk: chunk of interest |
| * @page_start: page index of the first page to unmap |
| * @page_end: page index of the last page to unmap + 1 |
| * @flush: whether to flush cache and tlb or not |
| * |
| * For each cpu, unmap pages [@page_start,@page_end) out of @chunk. |
| * If @flush is true, vcache is flushed before unmapping and tlb |
| * after. |
| */ |
| static void pcpu_unmap(struct pcpu_chunk *chunk, int page_start, int page_end, |
| bool flush) |
| { |
| unsigned int last = num_possible_cpus() - 1; |
| unsigned int cpu; |
| |
| /* unmap must not be done on immutable chunk */ |
| WARN_ON(chunk->immutable); |
| |
| /* |
| * Each flushing trial can be very expensive, issue flush on |
| * the whole region at once rather than doing it for each cpu. |
| * This could be an overkill but is more scalable. |
| */ |
| if (flush) |
| flush_cache_vunmap(pcpu_chunk_addr(chunk, 0, page_start), |
| pcpu_chunk_addr(chunk, last, page_end)); |
| |
| for_each_possible_cpu(cpu) |
| unmap_kernel_range_noflush( |
| pcpu_chunk_addr(chunk, cpu, page_start), |
| (page_end - page_start) << PAGE_SHIFT); |
| |
| /* ditto as flush_cache_vunmap() */ |
| if (flush) |
| flush_tlb_kernel_range(pcpu_chunk_addr(chunk, 0, page_start), |
| pcpu_chunk_addr(chunk, last, page_end)); |
| } |
| |
| /** |
| * pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk |
| * @chunk: chunk to depopulate |
| * @off: offset to the area to depopulate |
| * @size: size of the area to depopulate in bytes |
| * @flush: whether to flush cache and tlb or not |
| * |
| * For each cpu, depopulate and unmap pages [@page_start,@page_end) |
| * from @chunk. If @flush is true, vcache is flushed before unmapping |
| * and tlb after. |
| * |
| * CONTEXT: |
| * pcpu_alloc_mutex. |
| */ |
| static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size, |
| bool flush) |
| { |
| int page_start = PFN_DOWN(off); |
| int page_end = PFN_UP(off + size); |
| int unmap_start = -1; |
| int uninitialized_var(unmap_end); |
| unsigned int cpu; |
| int i; |
| |
| for (i = page_start; i < page_end; i++) { |
| for_each_possible_cpu(cpu) { |
| struct page **pagep = pcpu_chunk_pagep(chunk, cpu, i); |
| |
| if (!*pagep) |
| continue; |
| |
| __free_page(*pagep); |
| |
| /* |
| * If it's partial depopulation, it might get |
| * populated or depopulated again. Mark the |
| * page gone. |
| */ |
| *pagep = NULL; |
| |
| unmap_start = unmap_start < 0 ? i : unmap_start; |
| unmap_end = i + 1; |
| } |
| } |
| |
| if (unmap_start >= 0) |
| pcpu_unmap(chunk, unmap_start, unmap_end, flush); |
| } |
| |
| /** |
| * pcpu_map - map pages into a pcpu_chunk |
| * @chunk: chunk of interest |
| * @page_start: page index of the first page to map |
| * @page_end: page index of the last page to map + 1 |
| * |
| * For each cpu, map pages [@page_start,@page_end) into @chunk. |
| * vcache is flushed afterwards. |
| */ |
| static int pcpu_map(struct pcpu_chunk *chunk, int page_start, int page_end) |
| { |
| unsigned int last = num_possible_cpus() - 1; |
| unsigned int cpu; |
| int err; |
| |
| /* map must not be done on immutable chunk */ |
| WARN_ON(chunk->immutable); |
| |
| for_each_possible_cpu(cpu) { |
| err = map_kernel_range_noflush( |
| pcpu_chunk_addr(chunk, cpu, page_start), |
| (page_end - page_start) << PAGE_SHIFT, |
| PAGE_KERNEL, |
| pcpu_chunk_pagep(chunk, cpu, page_start)); |
| if (err < 0) |
| return err; |
| } |
| |
| /* flush at once, please read comments in pcpu_unmap() */ |
| flush_cache_vmap(pcpu_chunk_addr(chunk, 0, page_start), |
| pcpu_chunk_addr(chunk, last, page_end)); |
| return 0; |
| } |
| |
| /** |
| * pcpu_populate_chunk - populate and map an area of a pcpu_chunk |
| * @chunk: chunk of interest |
| * @off: offset to the area to populate |
| * @size: size of the area to populate in bytes |
| * |
| * For each cpu, populate and map pages [@page_start,@page_end) into |
| * @chunk. The area is cleared on return. |
| * |
| * CONTEXT: |
| * pcpu_alloc_mutex, does GFP_KERNEL allocation. |
| */ |
| static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size) |
| { |
| const gfp_t alloc_mask = GFP_KERNEL | __GFP_HIGHMEM | __GFP_COLD; |
| int page_start = PFN_DOWN(off); |
| int page_end = PFN_UP(off + size); |
| int map_start = -1; |
| int uninitialized_var(map_end); |
| unsigned int cpu; |
| int i; |
| |
| for (i = page_start; i < page_end; i++) { |
| if (pcpu_chunk_page_occupied(chunk, i)) { |
| if (map_start >= 0) { |
| if (pcpu_map(chunk, map_start, map_end)) |
| goto err; |
| map_start = -1; |
| } |
| continue; |
| } |
| |
| map_start = map_start < 0 ? i : map_start; |
| map_end = i + 1; |
| |
| for_each_possible_cpu(cpu) { |
| struct page **pagep = pcpu_chunk_pagep(chunk, cpu, i); |
| |
| *pagep = alloc_pages_node(cpu_to_node(cpu), |
| alloc_mask, 0); |
| if (!*pagep) |
| goto err; |
| } |
| } |
| |
| if (map_start >= 0 && pcpu_map(chunk, map_start, map_end)) |
| goto err; |
| |
| for_each_possible_cpu(cpu) |
| memset(chunk->vm->addr + cpu * pcpu_unit_size + off, 0, |
| size); |
| |
| return 0; |
| err: |
| /* likely under heavy memory pressure, give memory back */ |
| pcpu_depopulate_chunk(chunk, off, size, true); |
| return -ENOMEM; |
| } |
| |
| static void free_pcpu_chunk(struct pcpu_chunk *chunk) |
| { |
| if (!chunk) |
| return; |
| if (chunk->vm) |
| free_vm_area(chunk->vm); |
| pcpu_mem_free(chunk->map, chunk->map_alloc * sizeof(chunk->map[0])); |
| kfree(chunk); |
| } |
| |
| static struct pcpu_chunk *alloc_pcpu_chunk(void) |
| { |
| struct pcpu_chunk *chunk; |
| |
| chunk = kzalloc(pcpu_chunk_struct_size, GFP_KERNEL); |
| if (!chunk) |
| return NULL; |
| |
| chunk->map = pcpu_mem_alloc(PCPU_DFL_MAP_ALLOC * sizeof(chunk->map[0])); |
| chunk->map_alloc = PCPU_DFL_MAP_ALLOC; |
| chunk->map[chunk->map_used++] = pcpu_unit_size; |
| chunk->page = chunk->page_ar; |
| |
| chunk->vm = get_vm_area(pcpu_chunk_size, GFP_KERNEL); |
| if (!chunk->vm) { |
| free_pcpu_chunk(chunk); |
| return NULL; |
| } |
| |
| INIT_LIST_HEAD(&chunk->list); |
| chunk->free_size = pcpu_unit_size; |
| chunk->contig_hint = pcpu_unit_size; |
| |
| return chunk; |
| } |
| |
| /** |
| * 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 |
| * |
| * Allocate percpu area of @size bytes aligned at @align. |
| * |
| * CONTEXT: |
| * Does GFP_KERNEL allocation. |
| * |
| * RETURNS: |
| * Percpu pointer to the allocated area on success, NULL on failure. |
| */ |
| static void *pcpu_alloc(size_t size, size_t align, bool reserved) |
| { |
| struct pcpu_chunk *chunk; |
| int slot, off; |
| |
| if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) { |
| WARN(true, "illegal size (%zu) or align (%zu) for " |
| "percpu allocation\n", size, align); |
| return NULL; |
| } |
| |
| mutex_lock(&pcpu_alloc_mutex); |
| spin_lock_irq(&pcpu_lock); |
| |
| /* serve reserved allocations from the reserved chunk if available */ |
| if (reserved && pcpu_reserved_chunk) { |
| chunk = pcpu_reserved_chunk; |
| if (size > chunk->contig_hint || |
| pcpu_extend_area_map(chunk) < 0) |
| goto fail_unlock; |
| off = pcpu_alloc_area(chunk, size, align); |
| if (off >= 0) |
| goto area_found; |
| 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) { |
| if (size > chunk->contig_hint) |
| continue; |
| |
| switch (pcpu_extend_area_map(chunk)) { |
| case 0: |
| break; |
| case 1: |
| goto restart; /* pcpu_lock dropped, restart */ |
| default: |
| goto fail_unlock; |
| } |
| |
| off = pcpu_alloc_area(chunk, size, align); |
| if (off >= 0) |
| goto area_found; |
| } |
| } |
| |
| /* hmmm... no space left, create a new chunk */ |
| spin_unlock_irq(&pcpu_lock); |
| |
| chunk = alloc_pcpu_chunk(); |
| if (!chunk) |
| goto fail_unlock_mutex; |
| |
| spin_lock_irq(&pcpu_lock); |
| pcpu_chunk_relocate(chunk, -1); |
| pcpu_chunk_addr_insert(chunk); |
| goto restart; |
| |
| area_found: |
| spin_unlock_irq(&pcpu_lock); |
| |
| /* populate, map and clear the area */ |
| if (pcpu_populate_chunk(chunk, off, size)) { |
| spin_lock_irq(&pcpu_lock); |
| pcpu_free_area(chunk, off); |
| goto fail_unlock; |
| } |
| |
| mutex_unlock(&pcpu_alloc_mutex); |
| |
| return __addr_to_pcpu_ptr(chunk->vm->addr + off); |
| |
| fail_unlock: |
| spin_unlock_irq(&pcpu_lock); |
| fail_unlock_mutex: |
| mutex_unlock(&pcpu_alloc_mutex); |
| return NULL; |
| } |
| |
| /** |
| * __alloc_percpu - allocate dynamic percpu area |
| * @size: size of area to allocate in bytes |
| * @align: alignment of area (max PAGE_SIZE) |
| * |
| * Allocate percpu area of @size bytes aligned at @align. Might |
| * sleep. Might trigger writeouts. |
| * |
| * CONTEXT: |
| * Does GFP_KERNEL allocation. |
| * |
| * RETURNS: |
| * Percpu pointer to the allocated area on success, NULL on failure. |
| */ |
| void *__alloc_percpu(size_t size, size_t align) |
| { |
| return pcpu_alloc(size, align, false); |
| } |
| 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 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 *__alloc_reserved_percpu(size_t size, size_t align) |
| { |
| return pcpu_alloc(size, align, true); |
| } |
| |
| /** |
| * pcpu_reclaim - reclaim fully free chunks, workqueue function |
| * @work: unused |
| * |
| * Reclaim all fully free chunks except for the first one. |
| * |
| * CONTEXT: |
| * workqueue context. |
| */ |
| static void pcpu_reclaim(struct work_struct *work) |
| { |
| LIST_HEAD(todo); |
| struct list_head *head = &pcpu_slot[pcpu_nr_slots - 1]; |
| struct pcpu_chunk *chunk, *next; |
| |
| mutex_lock(&pcpu_alloc_mutex); |
| spin_lock_irq(&pcpu_lock); |
| |
| list_for_each_entry_safe(chunk, next, head, list) { |
| WARN_ON(chunk->immutable); |
| |
| /* spare the first one */ |
| if (chunk == list_first_entry(head, struct pcpu_chunk, list)) |
| continue; |
| |
| rb_erase(&chunk->rb_node, &pcpu_addr_root); |
| list_move(&chunk->list, &todo); |
| } |
| |
| spin_unlock_irq(&pcpu_lock); |
| mutex_unlock(&pcpu_alloc_mutex); |
| |
| list_for_each_entry_safe(chunk, next, &todo, list) { |
| pcpu_depopulate_chunk(chunk, 0, pcpu_unit_size, false); |
| free_pcpu_chunk(chunk); |
| } |
| } |
| |
| /** |
| * 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 *ptr) |
| { |
| void *addr = __pcpu_ptr_to_addr(ptr); |
| struct pcpu_chunk *chunk; |
| unsigned long flags; |
| int off; |
| |
| if (!ptr) |
| return; |
| |
| spin_lock_irqsave(&pcpu_lock, flags); |
| |
| chunk = pcpu_chunk_addr_search(addr); |
| off = addr - chunk->vm->addr; |
| |
| pcpu_free_area(chunk, off); |
| |
| /* if there are more than one fully free chunks, wake up grim reaper */ |
| if (chunk->free_size == pcpu_unit_size) { |
| struct pcpu_chunk *pos; |
| |
| list_for_each_entry(pos, &pcpu_slot[pcpu_nr_slots - 1], list) |
| if (pos != chunk) { |
| schedule_work(&pcpu_reclaim_work); |
| break; |
| } |
| } |
| |
| spin_unlock_irqrestore(&pcpu_lock, flags); |
| } |
| EXPORT_SYMBOL_GPL(free_percpu); |
| |
| /** |
| * pcpu_setup_first_chunk - initialize the first percpu chunk |
| * @get_page_fn: callback to fetch page pointer |
| * @static_size: the size of static percpu area in bytes |
| * @reserved_size: the size of reserved percpu area in bytes |
| * @dyn_size: free size for dynamic allocation in bytes, -1 for auto |
| * @unit_size: unit size in bytes, must be multiple of PAGE_SIZE, -1 for auto |
| * @base_addr: mapped address, NULL for auto |
| * @populate_pte_fn: callback to allocate pagetable, NULL if unnecessary |
| * |
| * Initialize the first percpu chunk which contains the kernel static |
| * perpcu area. This function is to be called from arch percpu area |
| * setup path. The first two parameters are mandatory. The rest are |
| * optional. |
| * |
| * @get_page_fn() should return pointer to percpu page given cpu |
| * number and page number. It should at least return enough pages to |
| * cover the static area. The returned pages for static area should |
| * have been initialized with valid data. If @unit_size is specified, |
| * it can also return pages after the static area. NULL return |
| * indicates end of pages for the cpu. Note that @get_page_fn() must |
| * return the same number of pages for all cpus. |
| * |
| * @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. |
| * |
| * @dyn_size, if non-negative, determines the number of bytes |
| * available for dynamic allocation in the first chunk. Specifying |
| * non-negative value makes percpu leave alone the area beyond |
| * @static_size + @reserved_size + @dyn_size. |
| * |
| * @unit_size, if non-negative, specifies unit size and must be |
| * aligned to PAGE_SIZE and equal to or larger than @static_size + |
| * @reserved_size + if non-negative, @dyn_size. |
| * |
| * Non-null @base_addr means that the caller already allocated virtual |
| * region for the first chunk and mapped it. percpu must not mess |
| * with the chunk. Note that @base_addr with 0 @unit_size or non-NULL |
| * @populate_pte_fn doesn't make any sense. |
| * |
| * @populate_pte_fn is used to populate the pagetable. NULL means the |
| * caller already populated the pagetable. |
| * |
| * If the first chunk ends up with both reserved and dynamic areas, it |
| * is served by two chunks - one to serve the core static and reserved |
| * areas and the other for the dynamic area. They share the same vm |
| * and page map but uses different area allocation map to stay away |
| * from each other. The latter chunk is circulated in the chunk slots |
| * and available for dynamic allocation like any other chunks. |
| * |
| * RETURNS: |
| * The determined pcpu_unit_size which can be used to initialize |
| * percpu access. |
| */ |
| size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn, |
| size_t static_size, size_t reserved_size, |
| ssize_t dyn_size, ssize_t unit_size, |
| void *base_addr, |
| pcpu_populate_pte_fn_t populate_pte_fn) |
| { |
| static struct vm_struct first_vm; |
| static int smap[2], dmap[2]; |
| size_t size_sum = static_size + reserved_size + |
| (dyn_size >= 0 ? dyn_size : 0); |
| struct pcpu_chunk *schunk, *dchunk = NULL; |
| unsigned int cpu; |
| int nr_pages; |
| int err, i; |
| |
| /* santiy checks */ |
| BUILD_BUG_ON(ARRAY_SIZE(smap) >= PCPU_DFL_MAP_ALLOC || |
| ARRAY_SIZE(dmap) >= PCPU_DFL_MAP_ALLOC); |
| BUG_ON(!static_size); |
| if (unit_size >= 0) { |
| BUG_ON(unit_size < size_sum); |
| BUG_ON(unit_size & ~PAGE_MASK); |
| BUG_ON(unit_size < PCPU_MIN_UNIT_SIZE); |
| } else |
| BUG_ON(base_addr); |
| BUG_ON(base_addr && populate_pte_fn); |
| |
| if (unit_size >= 0) |
| pcpu_unit_pages = unit_size >> PAGE_SHIFT; |
| else |
| pcpu_unit_pages = max_t(int, PCPU_MIN_UNIT_SIZE >> PAGE_SHIFT, |
| PFN_UP(size_sum)); |
| |
| pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT; |
| pcpu_chunk_size = num_possible_cpus() * pcpu_unit_size; |
| pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) |
| + num_possible_cpus() * pcpu_unit_pages * sizeof(struct page *); |
| |
| if (dyn_size < 0) |
| dyn_size = pcpu_unit_size - static_size - reserved_size; |
| |
| /* |
| * Allocate chunk slots. The additional last slot is for |
| * empty chunks. |
| */ |
| pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2; |
| pcpu_slot = alloc_bootmem(pcpu_nr_slots * sizeof(pcpu_slot[0])); |
| for (i = 0; i < pcpu_nr_slots; i++) |
| INIT_LIST_HEAD(&pcpu_slot[i]); |
| |
| /* |
| * Initialize static chunk. If reserved_size is zero, the |
| * static chunk covers static area + dynamic allocation area |
| * in the first chunk. If reserved_size is not zero, it |
| * covers static area + reserved area (mostly used for module |
| * static percpu allocation). |
| */ |
| schunk = alloc_bootmem(pcpu_chunk_struct_size); |
| INIT_LIST_HEAD(&schunk->list); |
| schunk->vm = &first_vm; |
| schunk->map = smap; |
| schunk->map_alloc = ARRAY_SIZE(smap); |
| schunk->page = schunk->page_ar; |
| |
| if (reserved_size) { |
| schunk->free_size = reserved_size; |
| pcpu_reserved_chunk = schunk; /* not for dynamic alloc */ |
| } else { |
| schunk->free_size = dyn_size; |
| dyn_size = 0; /* dynamic area covered */ |
| } |
| schunk->contig_hint = schunk->free_size; |
| |
| schunk->map[schunk->map_used++] = -static_size; |
| if (schunk->free_size) |
| schunk->map[schunk->map_used++] = schunk->free_size; |
| |
| pcpu_reserved_chunk_limit = static_size + schunk->free_size; |
| |
| /* init dynamic chunk if necessary */ |
| if (dyn_size) { |
| dchunk = alloc_bootmem(sizeof(struct pcpu_chunk)); |
| INIT_LIST_HEAD(&dchunk->list); |
| dchunk->vm = &first_vm; |
| dchunk->map = dmap; |
| dchunk->map_alloc = ARRAY_SIZE(dmap); |
| dchunk->page = schunk->page_ar; /* share page map with schunk */ |
| |
| dchunk->contig_hint = dchunk->free_size = dyn_size; |
| dchunk->map[dchunk->map_used++] = -pcpu_reserved_chunk_limit; |
| dchunk->map[dchunk->map_used++] = dchunk->free_size; |
| } |
| |
| /* allocate vm address */ |
| first_vm.flags = VM_ALLOC; |
| first_vm.size = pcpu_chunk_size; |
| |
| if (!base_addr) |
| vm_area_register_early(&first_vm, PAGE_SIZE); |
| else { |
| /* |
| * Pages already mapped. No need to remap into |
| * vmalloc area. In this case the first chunks can't |
| * be mapped or unmapped by percpu and are marked |
| * immutable. |
| */ |
| first_vm.addr = base_addr; |
| schunk->immutable = true; |
| if (dchunk) |
| dchunk->immutable = true; |
| } |
| |
| /* assign pages */ |
| nr_pages = -1; |
| for_each_possible_cpu(cpu) { |
| for (i = 0; i < pcpu_unit_pages; i++) { |
| struct page *page = get_page_fn(cpu, i); |
| |
| if (!page) |
| break; |
| *pcpu_chunk_pagep(schunk, cpu, i) = page; |
| } |
| |
| BUG_ON(i < PFN_UP(static_size)); |
| |
| if (nr_pages < 0) |
| nr_pages = i; |
| else |
| BUG_ON(nr_pages != i); |
| } |
| |
| /* map them */ |
| if (populate_pte_fn) { |
| for_each_possible_cpu(cpu) |
| for (i = 0; i < nr_pages; i++) |
| populate_pte_fn(pcpu_chunk_addr(schunk, |
| cpu, i)); |
| |
| err = pcpu_map(schunk, 0, nr_pages); |
| if (err) |
| panic("failed to setup static percpu area, err=%d\n", |
| err); |
| } |
| |
| /* link the first chunk in */ |
| if (!dchunk) { |
| pcpu_chunk_relocate(schunk, -1); |
| pcpu_chunk_addr_insert(schunk); |
| } else { |
| pcpu_chunk_relocate(dchunk, -1); |
| pcpu_chunk_addr_insert(dchunk); |
| } |
| |
| /* we're done */ |
| pcpu_base_addr = (void *)pcpu_chunk_addr(schunk, 0, 0); |
| return pcpu_unit_size; |
| } |