linux-hardened/mm/dmapool.c
Mateusz Nosek 1386f7a3bf mm/dmapool.c: micro-optimisation remove unnecessary branch
Previously there was a check if 'size' is aligned to 'align' and if not
then it was aligned.  This check was expensive as both branch and division
are expensive instructions in most architectures.  'ALIGN' function on
already aligned value will not change it, and as it is cheaper than branch
+ division it can be executed all the time and branch can be removed.

Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200320173317.26408-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 10:43:42 -07:00

535 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* DMA Pool allocator
*
* Copyright 2001 David Brownell
* Copyright 2007 Intel Corporation
* Author: Matthew Wilcox <willy@linux.intel.com>
*
* This allocator returns small blocks of a given size which are DMA-able by
* the given device. It uses the dma_alloc_coherent page allocator to get
* new pages, then splits them up into blocks of the required size.
* Many older drivers still have their own code to do this.
*
* The current design of this allocator is fairly simple. The pool is
* represented by the 'struct dma_pool' which keeps a doubly-linked list of
* allocated pages. Each page in the page_list is split into blocks of at
* least 'size' bytes. Free blocks are tracked in an unsorted singly-linked
* list of free blocks within the page. Used blocks aren't tracked, but we
* keep a count of how many are currently allocated from each page.
*/
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/export.h>
#include <linux/mutex.h>
#include <linux/poison.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/wait.h>
#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
#define DMAPOOL_DEBUG 1
#endif
struct dma_pool { /* the pool */
struct list_head page_list;
spinlock_t lock;
size_t size;
struct device *dev;
size_t allocation;
size_t boundary;
char name[32];
struct list_head pools;
};
struct dma_page { /* cacheable header for 'allocation' bytes */
struct list_head page_list;
void *vaddr;
dma_addr_t dma;
unsigned int in_use;
unsigned int offset;
};
static DEFINE_MUTEX(pools_lock);
static DEFINE_MUTEX(pools_reg_lock);
static ssize_t
show_pools(struct device *dev, struct device_attribute *attr, char *buf)
{
unsigned temp;
unsigned size;
char *next;
struct dma_page *page;
struct dma_pool *pool;
next = buf;
size = PAGE_SIZE;
temp = scnprintf(next, size, "poolinfo - 0.1\n");
size -= temp;
next += temp;
mutex_lock(&pools_lock);
list_for_each_entry(pool, &dev->dma_pools, pools) {
unsigned pages = 0;
unsigned blocks = 0;
spin_lock_irq(&pool->lock);
list_for_each_entry(page, &pool->page_list, page_list) {
pages++;
blocks += page->in_use;
}
spin_unlock_irq(&pool->lock);
/* per-pool info, no real statistics yet */
temp = scnprintf(next, size, "%-16s %4u %4zu %4zu %2u\n",
pool->name, blocks,
pages * (pool->allocation / pool->size),
pool->size, pages);
size -= temp;
next += temp;
}
mutex_unlock(&pools_lock);
return PAGE_SIZE - size;
}
static DEVICE_ATTR(pools, 0444, show_pools, NULL);
/**
* dma_pool_create - Creates a pool of consistent memory blocks, for dma.
* @name: name of pool, for diagnostics
* @dev: device that will be doing the DMA
* @size: size of the blocks in this pool.
* @align: alignment requirement for blocks; must be a power of two
* @boundary: returned blocks won't cross this power of two boundary
* Context: not in_interrupt()
*
* Given one of these pools, dma_pool_alloc()
* may be used to allocate memory. Such memory will all have "consistent"
* DMA mappings, accessible by the device and its driver without using
* cache flushing primitives. The actual size of blocks allocated may be
* larger than requested because of alignment.
*
* If @boundary is nonzero, objects returned from dma_pool_alloc() won't
* cross that size boundary. This is useful for devices which have
* addressing restrictions on individual DMA transfers, such as not crossing
* boundaries of 4KBytes.
*
* Return: a dma allocation pool with the requested characteristics, or
* %NULL if one can't be created.
*/
struct dma_pool *dma_pool_create(const char *name, struct device *dev,
size_t size, size_t align, size_t boundary)
{
struct dma_pool *retval;
size_t allocation;
bool empty = false;
if (align == 0)
align = 1;
else if (align & (align - 1))
return NULL;
if (size == 0)
return NULL;
else if (size < 4)
size = 4;
size = ALIGN(size, align);
allocation = max_t(size_t, size, PAGE_SIZE);
if (!boundary)
boundary = allocation;
else if ((boundary < size) || (boundary & (boundary - 1)))
return NULL;
retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
if (!retval)
return retval;
strlcpy(retval->name, name, sizeof(retval->name));
retval->dev = dev;
INIT_LIST_HEAD(&retval->page_list);
spin_lock_init(&retval->lock);
retval->size = size;
retval->boundary = boundary;
retval->allocation = allocation;
INIT_LIST_HEAD(&retval->pools);
/*
* pools_lock ensures that the ->dma_pools list does not get corrupted.
* pools_reg_lock ensures that there is not a race between
* dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
* when the first invocation of dma_pool_create() failed on
* device_create_file() and the second assumes that it has been done (I
* know it is a short window).
*/
mutex_lock(&pools_reg_lock);
mutex_lock(&pools_lock);
if (list_empty(&dev->dma_pools))
empty = true;
list_add(&retval->pools, &dev->dma_pools);
mutex_unlock(&pools_lock);
if (empty) {
int err;
err = device_create_file(dev, &dev_attr_pools);
if (err) {
mutex_lock(&pools_lock);
list_del(&retval->pools);
mutex_unlock(&pools_lock);
mutex_unlock(&pools_reg_lock);
kfree(retval);
return NULL;
}
}
mutex_unlock(&pools_reg_lock);
return retval;
}
EXPORT_SYMBOL(dma_pool_create);
static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
{
unsigned int offset = 0;
unsigned int next_boundary = pool->boundary;
do {
unsigned int next = offset + pool->size;
if (unlikely((next + pool->size) >= next_boundary)) {
next = next_boundary;
next_boundary += pool->boundary;
}
*(int *)(page->vaddr + offset) = next;
offset = next;
} while (offset < pool->allocation);
}
static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
{
struct dma_page *page;
page = kmalloc(sizeof(*page), mem_flags);
if (!page)
return NULL;
page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
&page->dma, mem_flags);
if (page->vaddr) {
#ifdef DMAPOOL_DEBUG
memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
#endif
pool_initialise_page(pool, page);
page->in_use = 0;
page->offset = 0;
} else {
kfree(page);
page = NULL;
}
return page;
}
static inline bool is_page_busy(struct dma_page *page)
{
return page->in_use != 0;
}
static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
{
dma_addr_t dma = page->dma;
#ifdef DMAPOOL_DEBUG
memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
#endif
dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
list_del(&page->page_list);
kfree(page);
}
/**
* dma_pool_destroy - destroys a pool of dma memory blocks.
* @pool: dma pool that will be destroyed
* Context: !in_interrupt()
*
* Caller guarantees that no more memory from the pool is in use,
* and that nothing will try to use the pool after this call.
*/
void dma_pool_destroy(struct dma_pool *pool)
{
bool empty = false;
if (unlikely(!pool))
return;
mutex_lock(&pools_reg_lock);
mutex_lock(&pools_lock);
list_del(&pool->pools);
if (pool->dev && list_empty(&pool->dev->dma_pools))
empty = true;
mutex_unlock(&pools_lock);
if (empty)
device_remove_file(pool->dev, &dev_attr_pools);
mutex_unlock(&pools_reg_lock);
while (!list_empty(&pool->page_list)) {
struct dma_page *page;
page = list_entry(pool->page_list.next,
struct dma_page, page_list);
if (is_page_busy(page)) {
if (pool->dev)
dev_err(pool->dev,
"dma_pool_destroy %s, %p busy\n",
pool->name, page->vaddr);
else
pr_err("dma_pool_destroy %s, %p busy\n",
pool->name, page->vaddr);
/* leak the still-in-use consistent memory */
list_del(&page->page_list);
kfree(page);
} else
pool_free_page(pool, page);
}
kfree(pool);
}
EXPORT_SYMBOL(dma_pool_destroy);
/**
* dma_pool_alloc - get a block of consistent memory
* @pool: dma pool that will produce the block
* @mem_flags: GFP_* bitmask
* @handle: pointer to dma address of block
*
* Return: the kernel virtual address of a currently unused block,
* and reports its dma address through the handle.
* If such a memory block can't be allocated, %NULL is returned.
*/
void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
dma_addr_t *handle)
{
unsigned long flags;
struct dma_page *page;
size_t offset;
void *retval;
might_sleep_if(gfpflags_allow_blocking(mem_flags));
spin_lock_irqsave(&pool->lock, flags);
list_for_each_entry(page, &pool->page_list, page_list) {
if (page->offset < pool->allocation)
goto ready;
}
/* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
spin_unlock_irqrestore(&pool->lock, flags);
page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
if (!page)
return NULL;
spin_lock_irqsave(&pool->lock, flags);
list_add(&page->page_list, &pool->page_list);
ready:
page->in_use++;
offset = page->offset;
page->offset = *(int *)(page->vaddr + offset);
retval = offset + page->vaddr;
*handle = offset + page->dma;
#ifdef DMAPOOL_DEBUG
{
int i;
u8 *data = retval;
/* page->offset is stored in first 4 bytes */
for (i = sizeof(page->offset); i < pool->size; i++) {
if (data[i] == POOL_POISON_FREED)
continue;
if (pool->dev)
dev_err(pool->dev,
"dma_pool_alloc %s, %p (corrupted)\n",
pool->name, retval);
else
pr_err("dma_pool_alloc %s, %p (corrupted)\n",
pool->name, retval);
/*
* Dump the first 4 bytes even if they are not
* POOL_POISON_FREED
*/
print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
data, pool->size, 1);
break;
}
}
if (!(mem_flags & __GFP_ZERO))
memset(retval, POOL_POISON_ALLOCATED, pool->size);
#endif
spin_unlock_irqrestore(&pool->lock, flags);
if (want_init_on_alloc(mem_flags))
memset(retval, 0, pool->size);
return retval;
}
EXPORT_SYMBOL(dma_pool_alloc);
static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
{
struct dma_page *page;
list_for_each_entry(page, &pool->page_list, page_list) {
if (dma < page->dma)
continue;
if ((dma - page->dma) < pool->allocation)
return page;
}
return NULL;
}
/**
* dma_pool_free - put block back into dma pool
* @pool: the dma pool holding the block
* @vaddr: virtual address of block
* @dma: dma address of block
*
* Caller promises neither device nor driver will again touch this block
* unless it is first re-allocated.
*/
void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
{
struct dma_page *page;
unsigned long flags;
unsigned int offset;
spin_lock_irqsave(&pool->lock, flags);
page = pool_find_page(pool, dma);
if (!page) {
spin_unlock_irqrestore(&pool->lock, flags);
if (pool->dev)
dev_err(pool->dev,
"dma_pool_free %s, %p/%lx (bad dma)\n",
pool->name, vaddr, (unsigned long)dma);
else
pr_err("dma_pool_free %s, %p/%lx (bad dma)\n",
pool->name, vaddr, (unsigned long)dma);
return;
}
offset = vaddr - page->vaddr;
if (want_init_on_free())
memset(vaddr, 0, pool->size);
#ifdef DMAPOOL_DEBUG
if ((dma - page->dma) != offset) {
spin_unlock_irqrestore(&pool->lock, flags);
if (pool->dev)
dev_err(pool->dev,
"dma_pool_free %s, %p (bad vaddr)/%pad\n",
pool->name, vaddr, &dma);
else
pr_err("dma_pool_free %s, %p (bad vaddr)/%pad\n",
pool->name, vaddr, &dma);
return;
}
{
unsigned int chain = page->offset;
while (chain < pool->allocation) {
if (chain != offset) {
chain = *(int *)(page->vaddr + chain);
continue;
}
spin_unlock_irqrestore(&pool->lock, flags);
if (pool->dev)
dev_err(pool->dev, "dma_pool_free %s, dma %pad already free\n",
pool->name, &dma);
else
pr_err("dma_pool_free %s, dma %pad already free\n",
pool->name, &dma);
return;
}
}
memset(vaddr, POOL_POISON_FREED, pool->size);
#endif
page->in_use--;
*(int *)vaddr = page->offset;
page->offset = offset;
/*
* Resist a temptation to do
* if (!is_page_busy(page)) pool_free_page(pool, page);
* Better have a few empty pages hang around.
*/
spin_unlock_irqrestore(&pool->lock, flags);
}
EXPORT_SYMBOL(dma_pool_free);
/*
* Managed DMA pool
*/
static void dmam_pool_release(struct device *dev, void *res)
{
struct dma_pool *pool = *(struct dma_pool **)res;
dma_pool_destroy(pool);
}
static int dmam_pool_match(struct device *dev, void *res, void *match_data)
{
return *(struct dma_pool **)res == match_data;
}
/**
* dmam_pool_create - Managed dma_pool_create()
* @name: name of pool, for diagnostics
* @dev: device that will be doing the DMA
* @size: size of the blocks in this pool.
* @align: alignment requirement for blocks; must be a power of two
* @allocation: returned blocks won't cross this boundary (or zero)
*
* Managed dma_pool_create(). DMA pool created with this function is
* automatically destroyed on driver detach.
*
* Return: a managed dma allocation pool with the requested
* characteristics, or %NULL if one can't be created.
*/
struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
size_t size, size_t align, size_t allocation)
{
struct dma_pool **ptr, *pool;
ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
if (!ptr)
return NULL;
pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
if (pool)
devres_add(dev, ptr);
else
devres_free(ptr);
return pool;
}
EXPORT_SYMBOL(dmam_pool_create);
/**
* dmam_pool_destroy - Managed dma_pool_destroy()
* @pool: dma pool that will be destroyed
*
* Managed dma_pool_destroy().
*/
void dmam_pool_destroy(struct dma_pool *pool)
{
struct device *dev = pool->dev;
WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
}
EXPORT_SYMBOL(dmam_pool_destroy);