blob: 7fb40bb1555a93a31d7823252bed224c5deb751a [file] [log] [blame]
/*
* 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 boot-time determined number of 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. On UMA, units corresponds directly to
* cpus. On NUMA, the mapping can be non-linear and even sparse.
* Percpu access can be done by configuring percpu base registers
* according to cpu to unit mapping and pcpu_unit_size.
*
* There are usually many small percpu allocations many of them being
* 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 can be determined from the address using the index field
* in the page struct. The index field contains a pointer to the chunk.
*
* To use this allocator, arch code should do the followings.
*
* - drop CONFIG_HAVE_LEGACY_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/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 <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 */
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 */
unsigned long populated[]; /* populated bitmap */
};
static int pcpu_unit_pages __read_mostly;
static int pcpu_unit_size __read_mostly;
static int pcpu_nr_units __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;
/* cpus with the lowest and highest unit numbers */
static unsigned int pcpu_first_unit_cpu __read_mostly;
static unsigned int pcpu_last_unit_cpu __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);
/* cpu -> unit map */
const int *pcpu_unit_map __read_mostly;
/*
* 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.
*/
static struct pcpu_chunk *pcpu_first_chunk;
/*
* Optional reserved chunk. This chunk reserves part of the first
* chunk and serves it for reserved allocations. The amount of
* reserved offset is in pcpu_reserved_chunk_limit. When reserved
* area doesn't exist, the following variables contain NULL and 0
* respectively.
*/
static struct pcpu_chunk *pcpu_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, populated bitmap and
* vmalloc mapping. The latter is a spinlock and protects the index
* data structures - chunk slots, 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 */
/* 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 pcpu_unit_map[cpu] * pcpu_unit_pages + 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 struct page *pcpu_chunk_page(struct pcpu_chunk *chunk,
unsigned int cpu, int page_idx)
{
/* must not be used on pre-mapped chunk */
WARN_ON(chunk->immutable);
return vmalloc_to_page((void *)pcpu_chunk_addr(chunk, cpu, page_idx));
}
/* 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 void pcpu_next_unpop(struct pcpu_chunk *chunk, int *rs, int *re, int end)
{
*rs = find_next_zero_bit(chunk->populated, end, *rs);
*re = find_next_bit(chunk->populated, end, *rs + 1);
}
static void pcpu_next_pop(struct pcpu_chunk *chunk, int *rs, int *re, int end)
{
*rs = find_next_bit(chunk->populated, end, *rs);
*re = find_next_zero_bit(chunk->populated, end, *rs + 1);
}
/*
* (Un)populated page region iterators. Iterate over (un)populated
* page regions betwen @start and @end in @chunk. @rs and @re should
* be integer variables and will be set to start and end page index of
* the current region.
*/
#define pcpu_for_each_unpop_region(chunk, rs, re, start, end) \
for ((rs) = (start), pcpu_next_unpop((chunk), &(rs), &(re), (end)); \
(rs) < (re); \
(rs) = (re) + 1, pcpu_next_unpop((chunk), &(rs), &(re), (end)))
#define pcpu_for_each_pop_region(chunk, rs, re, start, end) \
for ((rs) = (start), pcpu_next_pop((chunk), &(rs), &(re), (end)); \
(rs) < (re); \
(rs) = (re) + 1, pcpu_next_pop((chunk), &(rs), &(re), (end)))
/**
* 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]);
}
}
/**
* pcpu_chunk_addr_search - determine chunk containing specified address
* @addr: address for which the chunk needs to be determined.
*
* RETURNS:
* The address of the found chunk.
*/
static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
{
void *first_start = pcpu_first_chunk->vm->addr;
/* is it in the first chunk? */
if (addr >= first_start && addr < first_start + pcpu_unit_size) {
/* is it in the reserved area? */
if (addr < first_start + pcpu_reserved_chunk_limit)
return pcpu_reserved_chunk;
return pcpu_first_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_map[smp_processor_id()] * pcpu_unit_size;
return pcpu_get_page_chunk(vmalloc_to_page(addr));
}
/**
* 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_get_pages_and_bitmap - get temp pages array and bitmap
* @chunk: chunk of interest
* @bitmapp: output parameter for bitmap
* @may_alloc: may allocate the array
*
* Returns pointer to array of pointers to struct page and bitmap,
* both of which can be indexed with pcpu_page_idx(). The returned
* array is cleared to zero and *@bitmapp is copied from
* @chunk->populated. Note that there is only one array and bitmap
* and access exclusion is the caller's responsibility.
*
* CONTEXT:
* pcpu_alloc_mutex and does GFP_KERNEL allocation if @may_alloc.
* Otherwise, don't care.
*
* RETURNS:
* Pointer to temp pages array on success, NULL on failure.
*/
static struct page **pcpu_get_pages_and_bitmap(struct pcpu_chunk *chunk,
unsigned long **bitmapp,
bool may_alloc)
{
static struct page **pages;
static unsigned long *bitmap;
size_t pages_size = pcpu_nr_units * pcpu_unit_pages * sizeof(pages[0]);
size_t bitmap_size = BITS_TO_LONGS(pcpu_unit_pages) *
sizeof(unsigned long);
if (!pages || !bitmap) {
if (may_alloc && !pages)
pages = pcpu_mem_alloc(pages_size);
if (may_alloc && !bitmap)
bitmap = pcpu_mem_alloc(bitmap_size);
if (!pages || !bitmap)
return NULL;
}
memset(pages, 0, pages_size);
bitmap_copy(bitmap, chunk->populated, pcpu_unit_pages);
*bitmapp = bitmap;
return pages;
}
/**
* pcpu_free_pages - free pages which were allocated for @chunk
* @chunk: chunk pages were allocated for
* @pages: array of pages to be freed, indexed by pcpu_page_idx()
* @populated: populated bitmap
* @page_start: page index of the first page to be freed
* @page_end: page index of the last page to be freed + 1
*
* Free pages [@page_start and @page_end) in @pages for all units.
* The pages were allocated for @chunk.
*/
static void pcpu_free_pages(struct pcpu_chunk *chunk,
struct page **pages, unsigned long *populated,
int page_start, int page_end)
{
unsigned int cpu;
int i;
for_each_possible_cpu(cpu) {
for (i = page_start; i < page_end; i++) {
struct page *page = pages[pcpu_page_idx(cpu, i)];
if (page)
__free_page(page);
}
}
}
/**
* pcpu_alloc_pages - allocates pages for @chunk
* @chunk: target chunk
* @pages: array to put the allocated pages into, indexed by pcpu_page_idx()
* @populated: populated bitmap
* @page_start: page index of the first page to be allocated
* @page_end: page index of the last page to be allocated + 1
*
* Allocate pages [@page_start,@page_end) into @pages for all units.
* The allocation is for @chunk. Percpu core doesn't care about the
* content of @pages and will pass it verbatim to pcpu_map_pages().
*/
static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
struct page **pages, unsigned long *populated,
int page_start, int page_end)
{
const gfp_t gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_COLD;
unsigned int cpu;
int i;
for_each_possible_cpu(cpu) {
for (i = page_start; i < page_end; i++) {
struct page **pagep = &pages[pcpu_page_idx(cpu, i)];
*pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0);
if (!*pagep) {
pcpu_free_pages(chunk, pages, populated,
page_start, page_end);
return -ENOMEM;
}
}
}
return 0;
}
/**
* pcpu_pre_unmap_flush - flush cache prior to unmapping
* @chunk: chunk the regions to be flushed belongs to
* @page_start: page index of the first page to be flushed
* @page_end: page index of the last page to be flushed + 1
*
* Pages in [@page_start,@page_end) of @chunk are about to be
* unmapped. Flush cache. As 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.
*/
static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk,
int page_start, int page_end)
{
flush_cache_vunmap(
pcpu_chunk_addr(chunk, pcpu_first_unit_cpu, page_start),
pcpu_chunk_addr(chunk, pcpu_last_unit_cpu, page_end));
}
static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
{
unmap_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT);
}
/**
* pcpu_unmap_pages - unmap pages out of a pcpu_chunk
* @chunk: chunk of interest
* @pages: pages array which can be used to pass information to free
* @populated: populated bitmap
* @page_start: page index of the first page to unmap
* @page_end: page index of the last page to unmap + 1
*
* For each cpu, unmap pages [@page_start,@page_end) out of @chunk.
* Corresponding elements in @pages were cleared by the caller and can
* be used to carry information to pcpu_free_pages() which will be
* called after all unmaps are finished. The caller should call
* proper pre/post flush functions.
*/
static void pcpu_unmap_pages(struct pcpu_chunk *chunk,
struct page **pages, unsigned long *populated,
int page_start, int page_end)
{
unsigned int cpu;
int i;
for_each_possible_cpu(cpu) {
for (i = page_start; i < page_end; i++) {
struct page *page;
page = pcpu_chunk_page(chunk, cpu, i);
WARN_ON(!page);
pages[pcpu_page_idx(cpu, i)] = page;
}
__pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start),
page_end - page_start);
}
for (i = page_start; i < page_end; i++)
__clear_bit(i, populated);
}
/**
* pcpu_post_unmap_tlb_flush - flush TLB after unmapping
* @chunk: pcpu_chunk the regions to be flushed belong to
* @page_start: page index of the first page to be flushed
* @page_end: page index of the last page to be flushed + 1
*
* Pages [@page_start,@page_end) of @chunk have been unmapped. Flush
* TLB for the regions. This can be skipped if the area is to be
* returned to vmalloc as vmalloc will handle TLB flushing lazily.
*
* As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
* for the whole region.
*/
static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
int page_start, int page_end)
{
flush_tlb_kernel_range(
pcpu_chunk_addr(chunk, pcpu_first_unit_cpu, page_start),
pcpu_chunk_addr(chunk, pcpu_last_unit_cpu, page_end));
}
static int __pcpu_map_pages(unsigned long addr, struct page **pages,
int nr_pages)
{
return map_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT,
PAGE_KERNEL, pages);
}
/**
* pcpu_map_pages - map pages into a pcpu_chunk
* @chunk: chunk of interest
* @pages: pages array containing pages to be mapped
* @populated: populated bitmap
* @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. The
* caller is responsible for calling pcpu_post_map_flush() after all
* mappings are complete.
*
* This function is responsible for setting corresponding bits in
* @chunk->populated bitmap and whatever is necessary for reverse
* lookup (addr -> chunk).
*/
static int pcpu_map_pages(struct pcpu_chunk *chunk,
struct page **pages, unsigned long *populated,
int page_start, int page_end)
{
unsigned int cpu, tcpu;
int i, err;
for_each_possible_cpu(cpu) {
err = __pcpu_map_pages(pcpu_chunk_addr(chunk, cpu, page_start),
&pages[pcpu_page_idx(cpu, page_start)],
page_end - page_start);
if (err < 0)
goto err;
}
/* mapping successful, link chunk and mark populated */
for (i = page_start; i < page_end; i++) {
for_each_possible_cpu(cpu)
pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)],
chunk);
__set_bit(i, populated);
}
return 0;
err:
for_each_possible_cpu(tcpu) {
if (tcpu == cpu)
break;
__pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start),
page_end - page_start);
}
return err;
}
/**
* pcpu_post_map_flush - flush cache after mapping
* @chunk: pcpu_chunk the regions to be flushed belong to
* @page_start: page index of the first page to be flushed
* @page_end: page index of the last page to be flushed + 1
*
* Pages [@page_start,@page_end) of @chunk have been mapped. Flush
* cache.
*
* As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
* for the whole region.
*/
static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
int page_start, int page_end)
{
flush_cache_vmap(
pcpu_chunk_addr(chunk, pcpu_first_unit_cpu, page_start),
pcpu_chunk_addr(chunk, pcpu_last_unit_cpu, 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)
{
int page_start = PFN_DOWN(off);
int page_end = PFN_UP(off + size);
struct page **pages;
unsigned long *populated;
int rs, re;
/* quick path, check whether it's empty already */
pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
if (rs == page_start && re == page_end)
return;
break;
}
/* immutable chunks can't be depopulated */
WARN_ON(chunk->immutable);
/*
* If control reaches here, there must have been at least one
* successful population attempt so the temp pages array must
* be available now.
*/
pages = pcpu_get_pages_and_bitmap(chunk, &populated, false);
BUG_ON(!pages);
/* unmap and free */
pcpu_pre_unmap_flush(chunk, page_start, page_end);
pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)
pcpu_unmap_pages(chunk, pages, populated, rs, re);
/* no need to flush tlb, vmalloc will handle it lazily */
pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)
pcpu_free_pages(chunk, pages, populated, rs, re);
/* commit new bitmap */
bitmap_copy(chunk->populated, populated, pcpu_unit_pages);
}
/**
* 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)
{
int page_start = PFN_DOWN(off);
int page_end = PFN_UP(off + size);
int free_end = page_start, unmap_end = page_start;
struct page **pages;
unsigned long *populated;
unsigned int cpu;
int rs, re, rc;
/* quick path, check whether all pages are already there */
pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end) {
if (rs == page_start && re == page_end)
goto clear;
break;
}
/* need to allocate and map pages, this chunk can't be immutable */
WARN_ON(chunk->immutable);
pages = pcpu_get_pages_and_bitmap(chunk, &populated, true);
if (!pages)
return -ENOMEM;
/* alloc and map */
pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
rc = pcpu_alloc_pages(chunk, pages, populated, rs, re);
if (rc)
goto err_free;
free_end = re;
}
pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
rc = pcpu_map_pages(chunk, pages, populated, rs, re);
if (rc)
goto err_unmap;
unmap_end = re;
}
pcpu_post_map_flush(chunk, page_start, page_end);
/* commit new bitmap */
bitmap_copy(chunk->populated, populated, pcpu_unit_pages);
clear:
for_each_possible_cpu(cpu)
memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
return 0;
err_unmap:
pcpu_pre_unmap_flush(chunk, page_start, unmap_end);
pcpu_for_each_unpop_region(chunk, rs, re, page_start, unmap_end)
pcpu_unmap_pages(chunk, pages, populated, rs, re);
pcpu_post_unmap_tlb_flush(chunk, page_start, unmap_end);
err_free:
pcpu_for_each_unpop_region(chunk, rs, re, page_start, free_end)
pcpu_free_pages(chunk, pages, populated, rs, re);
return rc;
}
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->vm = get_vm_area(pcpu_chunk_size, VM_ALLOC);
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);
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 address relative to unit0 */
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;
list_move(&chunk->list, &todo);
}
spin_unlock_irq(&pcpu_lock);
list_for_each_entry_safe(chunk, next, &todo, list) {
pcpu_depopulate_chunk(chunk, 0, pcpu_unit_size);
free_pcpu_chunk(chunk);
}
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 *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
* @static_size: the size of static percpu area in bytes
* @reserved_size: the size of reserved percpu area in bytes, 0 for none
* @dyn_size: free size for dynamic allocation in bytes, -1 for auto
* @unit_size: unit size in bytes, must be multiple of PAGE_SIZE
* @base_addr: mapped address
* @unit_map: cpu -> unit map, NULL for sequential mapping
*
* Initialize the first percpu chunk which contains the kernel static
* perpcu area. This function is to be called from arch percpu area
* setup path.
*
* @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 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.
*
* The caller should have mapped the first chunk at @base_addr and
* copied static data to each unit.
*
* 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(size_t static_size, size_t reserved_size,
ssize_t dyn_size, size_t unit_size,
void *base_addr, const int *unit_map)
{
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, tcpu;
int i;
/* sanity checks */
BUILD_BUG_ON(ARRAY_SIZE(smap) >= PCPU_DFL_MAP_ALLOC ||
ARRAY_SIZE(dmap) >= PCPU_DFL_MAP_ALLOC);
BUG_ON(!static_size);
BUG_ON(!base_addr);
BUG_ON(unit_size < size_sum);
BUG_ON(unit_size & ~PAGE_MASK);
BUG_ON(unit_size < PCPU_MIN_UNIT_SIZE);
/* determine number of units and verify and initialize pcpu_unit_map */
if (unit_map) {
int first_unit = INT_MAX, last_unit = INT_MIN;
for_each_possible_cpu(cpu) {
int unit = unit_map[cpu];
BUG_ON(unit < 0);
for_each_possible_cpu(tcpu) {
if (tcpu == cpu)
break;
/* the mapping should be one-to-one */
BUG_ON(unit_map[tcpu] == unit);
}
if (unit < first_unit) {
pcpu_first_unit_cpu = cpu;
first_unit = unit;
}
if (unit > last_unit) {
pcpu_last_unit_cpu = cpu;
last_unit = unit;
}
}
pcpu_nr_units = last_unit + 1;
pcpu_unit_map = unit_map;
} else {
int *identity_map;
/* #units == #cpus, identity mapped */
identity_map = alloc_bootmem(nr_cpu_ids *
sizeof(identity_map[0]));
for_each_possible_cpu(cpu)
identity_map[cpu] = cpu;
pcpu_first_unit_cpu = 0;
pcpu_last_unit_cpu = pcpu_nr_units - 1;
pcpu_nr_units = nr_cpu_ids;
pcpu_unit_map = identity_map;
}
/* determine basic parameters */
pcpu_unit_pages = unit_size >> PAGE_SHIFT;
pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
pcpu_chunk_size = pcpu_nr_units * pcpu_unit_size;
pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
if (dyn_size < 0)
dyn_size = pcpu_unit_size - static_size - reserved_size;
first_vm.flags = VM_ALLOC;
first_vm.size = pcpu_chunk_size;
first_vm.addr = base_addr;
/*
* 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->immutable = true;
bitmap_fill(schunk->populated, pcpu_unit_pages);
if (reserved_size) {
schunk->free_size = reserved_size;
pcpu_reserved_chunk = schunk;
pcpu_reserved_chunk_limit = static_size + reserved_size;
} 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;
/* init dynamic chunk if necessary */
if (dyn_size) {
dchunk = alloc_bootmem(pcpu_chunk_struct_size);
INIT_LIST_HEAD(&dchunk->list);
dchunk->vm = &first_vm;
dchunk->map = dmap;
dchunk->map_alloc = ARRAY_SIZE(dmap);
dchunk->immutable = true;
bitmap_fill(dchunk->populated, pcpu_unit_pages);
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;
}
/* link the first chunk in */
pcpu_first_chunk = dchunk ?: schunk;
pcpu_chunk_relocate(pcpu_first_chunk, -1);
/* we're done */
pcpu_base_addr = schunk->vm->addr;
return pcpu_unit_size;
}
const char *pcpu_fc_names[PCPU_FC_NR] __initdata = {
[PCPU_FC_AUTO] = "auto",
[PCPU_FC_EMBED] = "embed",
[PCPU_FC_PAGE] = "page",
[PCPU_FC_LPAGE] = "lpage",
};
enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
static int __init percpu_alloc_setup(char *str)
{
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
#ifdef CONFIG_NEED_PER_CPU_LPAGE_FIRST_CHUNK
else if (!strcmp(str, "lpage"))
pcpu_chosen_fc = PCPU_FC_LPAGE;
#endif
else
pr_warning("PERCPU: unknown allocator %s specified\n", str);
return 0;
}
early_param("percpu_alloc", percpu_alloc_setup);
static inline size_t pcpu_calc_fc_sizes(size_t static_size,
size_t reserved_size,
ssize_t *dyn_sizep)
{
size_t size_sum;
size_sum = PFN_ALIGN(static_size + reserved_size +
(*dyn_sizep >= 0 ? *dyn_sizep : 0));
if (*dyn_sizep != 0)
*dyn_sizep = size_sum - static_size - reserved_size;
return size_sum;
}
#if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
!defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
/**
* pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
* @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
*
* 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
* as a contiguous area using bootmem allocator and used as-is without
* being mapped into vmalloc area. This enables the first chunk to
* piggy back on the linear physical mapping which often uses larger
* page size.
*
* When @dyn_size is positive, dynamic area might be larger than
* specified to fill page alignment. When @dyn_size is auto,
* @dyn_size is just big enough to fill page alignment after static
* and reserved areas.
*
* If the needed size is smaller than the minimum or specified unit
* size, the leftover is returned to the bootmem allocator.
*
* RETURNS:
* The determined pcpu_unit_size which can be used to initialize
* percpu access on success, -errno on failure.
*/
ssize_t __init pcpu_embed_first_chunk(size_t static_size, size_t reserved_size,
ssize_t dyn_size)
{
size_t size_sum, unit_size, chunk_size;
void *base;
unsigned int cpu;
/* determine parameters and allocate */
size_sum = pcpu_calc_fc_sizes(static_size, reserved_size, &dyn_size);
unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
chunk_size = unit_size * nr_cpu_ids;
base = __alloc_bootmem_nopanic(chunk_size, PAGE_SIZE,
__pa(MAX_DMA_ADDRESS));
if (!base) {
pr_warning("PERCPU: failed to allocate %zu bytes for "
"embedding\n", chunk_size);
return -ENOMEM;
}
/* return the leftover and copy */
for (cpu = 0; cpu < nr_cpu_ids; cpu++) {
void *ptr = base + cpu * unit_size;
if (cpu_possible(cpu)) {
free_bootmem(__pa(ptr + size_sum),
unit_size - size_sum);
memcpy(ptr, __per_cpu_load, static_size);
} else
free_bootmem(__pa(ptr), unit_size);
}
/* we're ready, commit */
pr_info("PERCPU: Embedded %zu pages/cpu @%p s%zu r%zu d%zu u%zu\n",
PFN_DOWN(size_sum), base, static_size, reserved_size, dyn_size,
unit_size);
return pcpu_setup_first_chunk(static_size, reserved_size, dyn_size,
unit_size, base, NULL);
}
#endif /* CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK ||
!CONFIG_HAVE_SETUP_PER_CPU_AREA */
#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
/**
* pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
* @static_size: the size of static percpu area in bytes
* @reserved_size: the size of reserved percpu area in bytes
* @alloc_fn: function to allocate percpu page, always called with PAGE_SIZE
* @free_fn: funtion 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:
* The determined pcpu_unit_size which can be used to initialize
* percpu access on success, -errno on failure.
*/
ssize_t __init pcpu_page_first_chunk(size_t static_size, 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;
char psize_str[16];
int unit_pages;
size_t pages_size;
struct page **pages;
unsigned int cpu;
int i, j;
ssize_t ret;
snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);
unit_pages = PFN_UP(max_t(size_t, static_size + reserved_size,
PCPU_MIN_UNIT_SIZE));
/* unaligned allocations can't be freed, round up to page size */
pages_size = PFN_ALIGN(unit_pages * nr_cpu_ids * sizeof(pages[0]));
pages = alloc_bootmem(pages_size);
/* allocate pages */
j = 0;
for_each_possible_cpu(cpu)
for (i = 0; i < unit_pages; i++) {
void *ptr;
ptr = alloc_fn(cpu, PAGE_SIZE);
if (!ptr) {
pr_warning("PERCPU: failed to allocate %s page "
"for cpu%u\n", psize_str, cpu);
goto enomem;
}
pages[j++] = virt_to_page(ptr);
}
/* allocate vm area, map the pages and copy static data */
vm.flags = VM_ALLOC;
vm.size = nr_cpu_ids * unit_pages << PAGE_SHIFT;
vm_area_register_early(&vm, PAGE_SIZE);
for_each_possible_cpu(cpu) {
unsigned long unit_addr = (unsigned long)vm.addr +
(cpu * unit_pages << PAGE_SHIFT);
for (i = 0; i < unit_pages; i++)
populate_pte_fn(unit_addr + (i << PAGE_SHIFT));
/* pte already populated, the following shouldn't fail */
ret = __pcpu_map_pages(unit_addr, &pages[cpu * unit_pages],
unit_pages);
if (ret < 0)
panic("failed to map percpu area, err=%zd\n", ret);
/*
* 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, static_size);
}
/* we're ready, commit */
pr_info("PERCPU: %d %s pages/cpu @%p s%zu r%zu\n",
unit_pages, psize_str, vm.addr, static_size, reserved_size);
ret = pcpu_setup_first_chunk(static_size, reserved_size, -1,
unit_pages << PAGE_SHIFT, vm.addr, NULL);
goto out_free_ar;
enomem:
while (--j >= 0)
free_fn(page_address(pages[j]), PAGE_SIZE);
ret = -ENOMEM;
out_free_ar:
free_bootmem(__pa(pages), pages_size);
return ret;
}
#endif /* CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK */
#ifdef CONFIG_NEED_PER_CPU_LPAGE_FIRST_CHUNK
/**
* pcpu_lpage_build_unit_map - build unit_map for large page remapping
* @static_size: the size of static percpu area in bytes
* @reserved_size: the size of reserved percpu area in bytes
* @dyn_sizep: in/out parameter for dynamic size, -1 for auto
* @unit_sizep: out parameter for unit size
* @unit_map: unit_map to be filled
* @cpu_distance_fn: callback to determine distance between cpus
*
* This function builds cpu -> unit map and determine other parameters
* considering needed percpu size, large page size and distances
* between CPUs in NUMA.
*
* CPUs which are of LOCAL_DISTANCE both ways are grouped together and
* may share units in the same large page. The returned configuration
* is guaranteed to have CPUs on different nodes on different large
* pages and >=75% usage of allocated virtual address space.
*
* RETURNS:
* On success, fills in @unit_map, sets *@dyn_sizep, *@unit_sizep and
* returns the number of units to be allocated. -errno on failure.
*/
int __init pcpu_lpage_build_unit_map(size_t static_size, size_t reserved_size,
ssize_t *dyn_sizep, size_t *unit_sizep,
size_t lpage_size, int *unit_map,
pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
{
static int group_map[NR_CPUS] __initdata;
static int group_cnt[NR_CPUS] __initdata;
int group_cnt_max = 0;
size_t size_sum, min_unit_size, alloc_size;
int upa, max_upa, uninitialized_var(best_upa); /* units_per_alloc */
int last_allocs;
unsigned int cpu, tcpu;
int group, unit;
/*
* Determine min_unit_size, alloc_size and max_upa such that
* alloc_size is multiple of lpage_size and is the smallest
* which can accomodate 4k aligned segments which are equal to
* or larger than min_unit_size.
*/
size_sum = pcpu_calc_fc_sizes(static_size, reserved_size, dyn_sizep);
min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
alloc_size = roundup(min_unit_size, lpage_size);
upa = alloc_size / min_unit_size;
while (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
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, tcpu) > LOCAL_DISTANCE ||
cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) {
group++;
goto next_group;
}
}
group_map[cpu] = group;
group_cnt[group]++;
group_cnt_max = max(group_cnt_max, group_cnt[group]);
}
/*
* Expand unit size until address space usage goes over 75%
* and then as much as possible without using more address
* space.
*/
last_allocs = INT_MAX;
for (upa = max_upa; upa; upa--) {
int allocs = 0, wasted = 0;
if (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
continue;
for (group = 0; group_cnt[group]; 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 25%. 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;
}
*unit_sizep = alloc_size / best_upa;
/* assign units to cpus accordingly */
unit = 0;
for (group = 0; group_cnt[group]; group++) {
for_each_possible_cpu(cpu)
if (group_map[cpu] == group)
unit_map[cpu] = unit++;
unit = roundup(unit, best_upa);
}
return unit; /* unit contains aligned number of units */
}
struct pcpul_ent {
void *ptr;
void *map_addr;
};
static size_t pcpul_size;
static size_t pcpul_lpage_size;
static int pcpul_nr_lpages;
static struct pcpul_ent *pcpul_map;
static bool __init pcpul_unit_to_cpu(int unit, const int *unit_map,
unsigned int *cpup)
{
unsigned int cpu;
for_each_possible_cpu(cpu)
if (unit_map[cpu] == unit) {
if (cpup)
*cpup = cpu;
return true;
}
return false;
}
static void __init pcpul_lpage_dump_cfg(const char *lvl, size_t static_size,
size_t reserved_size, size_t dyn_size,
size_t unit_size, size_t lpage_size,
const int *unit_map, int nr_units)
{
int width = 1, v = nr_units;
char empty_str[] = "--------";
int upl, lpl; /* units per lpage, lpage per line */
unsigned int cpu;
int lpage, unit;
while (v /= 10)
width++;
empty_str[min_t(int, width, sizeof(empty_str) - 1)] = '\0';
upl = max_t(int, lpage_size / unit_size, 1);
lpl = rounddown_pow_of_two(max_t(int, 60 / (upl * (width + 1) + 2), 1));
printk("%spcpu-lpage: sta/res/dyn=%zu/%zu/%zu unit=%zu lpage=%zu", lvl,
static_size, reserved_size, dyn_size, unit_size, lpage_size);
for (lpage = 0, unit = 0; unit < nr_units; unit++) {
if (!(unit % upl)) {
if (!(lpage++ % lpl)) {
printk("\n");
printk("%spcpu-lpage: ", lvl);
} else
printk("| ");
}
if (pcpul_unit_to_cpu(unit, unit_map, &cpu))
printk("%0*d ", width, cpu);
else
printk("%s ", empty_str);
}
printk("\n");
}
/**
* pcpu_lpage_first_chunk - remap the first percpu chunk using large page
* @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
* @unit_size: unit size in bytes
* @lpage_size: the size of a large page
* @unit_map: cpu -> unit mapping
* @nr_units: the number of units
* @alloc_fn: function to allocate percpu lpage, always called with lpage_size
* @free_fn: function to free percpu memory, @size <= lpage_size
* @map_fn: function to map percpu lpage, always called with lpage_size
*
* This allocator uses large page to build and map the first chunk.
* Unlike other helpers, the caller should always specify @dyn_size
* and @unit_size. These parameters along with @unit_map and
* @nr_units can be determined using pcpu_lpage_build_unit_map().
* This two stage initialization is to allow arch code to evaluate the
* parameters before committing to it.
*
* Large pages are allocated as directed by @unit_map and other
* parameters and mapped to vmalloc space. Unused holes are returned
* to the page allocator. Note that these holes end up being actively
* mapped twice - once to the physical mapping and to the vmalloc area
* for the first percpu chunk. Depending on architecture, this might
* cause problem when changing page attributes of the returned area.
* These double mapped areas can be detected using
* pcpu_lpage_remapped().
*
* RETURNS:
* The determined pcpu_unit_size which can be used to initialize
* percpu access on success, -errno on failure.
*/
ssize_t __init pcpu_lpage_first_chunk(size_t static_size, size_t reserved_size,
size_t dyn_size, size_t unit_size,
size_t lpage_size, const int *unit_map,
int nr_units,
pcpu_fc_alloc_fn_t alloc_fn,
pcpu_fc_free_fn_t free_fn,
pcpu_fc_map_fn_t map_fn)
{
static struct vm_struct vm;
size_t chunk_size = unit_size * nr_units;
size_t map_size;
unsigned int cpu;
ssize_t ret;
int i, j, unit;
pcpul_lpage_dump_cfg(KERN_DEBUG, static_size, reserved_size, dyn_size,
unit_size, lpage_size, unit_map, nr_units);
BUG_ON(chunk_size % lpage_size);
pcpul_size = static_size + reserved_size + dyn_size;
pcpul_lpage_size = lpage_size;
pcpul_nr_lpages = chunk_size / lpage_size;
/* allocate pointer array and alloc large pages */
map_size = pcpul_nr_lpages * sizeof(pcpul_map[0]);
pcpul_map = alloc_bootmem(map_size);
/* allocate all pages */
for (i = 0; i < pcpul_nr_lpages; i++) {
size_t offset = i * lpage_size;
int first_unit = offset / unit_size;
int last_unit = (offset + lpage_size - 1) / unit_size;
void *ptr;
/* find out which cpu is mapped to this unit */
for (unit = first_unit; unit <= last_unit; unit++)
if (pcpul_unit_to_cpu(unit, unit_map, &cpu))
goto found;
continue;
found:
ptr = alloc_fn(cpu, lpage_size);
if (!ptr) {
pr_warning("PERCPU: failed to allocate large page "
"for cpu%u\n", cpu);
goto enomem;
}
pcpul_map[i].ptr = ptr;
}
/* return unused holes */
for (unit = 0; unit < nr_units; unit++) {
size_t start = unit * unit_size;
size_t end = start + unit_size;
size_t off, next;
/* don't free used part of occupied unit */
if (pcpul_unit_to_cpu(unit, unit_map, NULL))
start += pcpul_size;
/* unit can span more than one page, punch the holes */
for (off = start; off < end; off = next) {
void *ptr = pcpul_map[off / lpage_size].ptr;
next = min(roundup(off + 1, lpage_size), end);
if (ptr)
free_fn(ptr + off % lpage_size, next - off);
}
}
/* allocate address, map and copy */
vm.flags = VM_ALLOC;
vm.size = chunk_size;
vm_area_register_early(&vm, unit_size);
for (i = 0; i < pcpul_nr_lpages; i++) {
if (!pcpul_map[i].ptr)
continue;
pcpul_map[i].map_addr = vm.addr + i * lpage_size;
map_fn(pcpul_map[i].ptr, lpage_size, pcpul_map[i].map_addr);
}
for_each_possible_cpu(cpu)
memcpy(vm.addr + unit_map[cpu] * unit_size, __per_cpu_load,
static_size);
/* we're ready, commit */
pr_info("PERCPU: large pages @%p s%zu r%zu d%zu u%zu\n",
vm.addr, static_size, reserved_size, dyn_size, unit_size);
ret = pcpu_setup_first_chunk(static_size, reserved_size, dyn_size,
unit_size, vm.addr, unit_map);
/*
* Sort pcpul_map array for pcpu_lpage_remapped(). Unmapped
* lpages are pushed to the end and trimmed.
*/
for (i = 0; i < pcpul_nr_lpages - 1; i++)
for (j = i + 1; j < pcpul_nr_lpages; j++) {
struct pcpul_ent tmp;
if (!pcpul_map[j].ptr)
continue;
if (pcpul_map[i].ptr &&
pcpul_map[i].ptr < pcpul_map[j].ptr)
continue;
tmp = pcpul_map[i];
pcpul_map[i] = pcpul_map[j];
pcpul_map[j] = tmp;
}
while (pcpul_nr_lpages && !pcpul_map[pcpul_nr_lpages - 1].ptr)
pcpul_nr_lpages--;
return ret;
enomem:
for (i = 0; i < pcpul_nr_lpages; i++)
if (pcpul_map[i].ptr)
free_fn(pcpul_map[i].ptr, lpage_size);
free_bootmem(__pa(pcpul_map), map_size);
return -ENOMEM;
}
/**
* pcpu_lpage_remapped - determine whether a kaddr is in pcpul recycled area
* @kaddr: the kernel address in question
*
* Determine whether @kaddr falls in the pcpul recycled area. This is
* used by pageattr to detect VM aliases and break up the pcpu large
* page mapping such that the same physical page is not mapped under
* different attributes.
*
* The recycled area is always at the tail of a partially used large
* page.
*
* RETURNS:
* Address of corresponding remapped pcpu address if match is found;
* otherwise, NULL.
*/
void *pcpu_lpage_remapped(void *kaddr)
{
unsigned long lpage_mask = pcpul_lpage_size - 1;
void *lpage_addr = (void *)((unsigned long)kaddr & ~lpage_mask);
unsigned long offset = (unsigned long)kaddr & lpage_mask;
int left = 0, right = pcpul_nr_lpages - 1;
int pos;
/* pcpul in use at all? */
if (!pcpul_map)
return NULL;
/* okay, perform binary search */
while (left <= right) {
pos = (left + right) / 2;
if (pcpul_map[pos].ptr < lpage_addr)
left = pos + 1;
else if (pcpul_map[pos].ptr > lpage_addr)
right = pos - 1;
else
return pcpul_map[pos].map_addr + offset;
}
return NULL;
}
#endif /* CONFIG_NEED_PER_CPU_LPAGE_FIRST_CHUNK */
/*
* Generic 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.
*/
#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
EXPORT_SYMBOL(__per_cpu_offset);
void __init setup_per_cpu_areas(void)
{
size_t static_size = __per_cpu_end - __per_cpu_start;
ssize_t unit_size;
unsigned long delta;
unsigned int cpu;
/*
* Always reserve area for module percpu variables. That's
* what the legacy allocator did.
*/
unit_size = pcpu_embed_first_chunk(static_size, PERCPU_MODULE_RESERVE,
PERCPU_DYNAMIC_RESERVE);
if (unit_size < 0)
panic("Failed to initialized percpu areas.");
delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
for_each_possible_cpu(cpu)
__per_cpu_offset[cpu] = delta + cpu * unit_size;
}
#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */