[linux.git] / mm / percpu-km.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * mm/percpu-km.c - kernel memory based chunk allocation
 *
 * Copyright (C) 2010		SUSE Linux Products GmbH
 * Copyright (C) 2010		Tejun Heo <[email protected]>
 *
 * Chunks are allocated as a contiguous kernel memory using gfp
 * allocation.  This is to be used on nommu architectures.
 *
 * To use percpu-km,
 *
 * - define CONFIG_NEED_PER_CPU_KM from the arch Kconfig.
 *
 * - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK must not be defined.  It's
 *   not compatible with PER_CPU_KM.  EMBED_FIRST_CHUNK should work
 *   fine.
 *
 * - NUMA is not supported.  When setting up the first chunk,
 *   @cpu_distance_fn should be NULL or report all CPUs to be nearer
 *   than or at LOCAL_DISTANCE.
 *
 * - It's best if the chunk size is power of two multiple of
 *   PAGE_SIZE.  Because each chunk is allocated as a contiguous
 *   kernel memory block using alloc_pages(), memory will be wasted if
 *   chunk size is not aligned.  percpu-km code will whine about it.
 */

#if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
#error "contiguous percpu allocation is incompatible with paged first chunk"
#endif

#include <linux/log2.h>

static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
				      int page_start, int page_end)
{
	/* nothing */
}

static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
			       int page_start, int page_end, gfp_t gfp)
{
	return 0;
}

static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
				  int page_start, int page_end)
{
	/* nada */
}

static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
{
	const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
	struct pcpu_chunk *chunk;
	struct page *pages;
	unsigned long flags;
	int i;

	chunk = pcpu_alloc_chunk(gfp);
	if (!chunk)
		return NULL;

	pages = alloc_pages(gfp, order_base_2(nr_pages));
	if (!pages) {
		pcpu_free_chunk(chunk);
		return NULL;
	}

	for (i = 0; i < nr_pages; i++)
		pcpu_set_page_chunk(nth_page(pages, i), chunk);

	chunk->data = pages;
	chunk->base_addr = page_address(pages);

	spin_lock_irqsave(&pcpu_lock, flags);
	pcpu_chunk_populated(chunk, 0, nr_pages);
	spin_unlock_irqrestore(&pcpu_lock, flags);

	pcpu_stats_chunk_alloc();
	trace_percpu_create_chunk(chunk->base_addr);

	return chunk;
}

static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
{
	const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;

	if (!chunk)
		return;

	pcpu_stats_chunk_dealloc();
	trace_percpu_destroy_chunk(chunk->base_addr);

	if (chunk->data)
		__free_pages(chunk->data, order_base_2(nr_pages));
	pcpu_free_chunk(chunk);
}

static struct page *pcpu_addr_to_page(void *addr)
{
	return virt_to_page(addr);
}

static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
{
	size_t nr_pages, alloc_pages;

	/* all units must be in a single group */
	if (ai->nr_groups != 1) {
		pr_crit("can't handle more than one group\n");
		return -EINVAL;
	}

	nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT;
	alloc_pages = roundup_pow_of_two(nr_pages);

	if (alloc_pages > nr_pages)
		pr_warn("wasting %zu pages per chunk\n",
			alloc_pages - nr_pages);

	return 0;
}

static bool pcpu_should_reclaim_chunk(struct pcpu_chunk *chunk)
{
	return false;
}
Commit	Line	Data
55716d26	1	// SPDX-License-Identifier: GPL-2.0-only
b0c9778b TH	2	/*
	3	* mm/percpu-km.c - kernel memory based chunk allocation
	4	*
	5	* Copyright (C) 2010 SUSE Linux Products GmbH
	6	* Copyright (C) 2010 Tejun Heo <[email protected]>
	7	*
b0c9778b TH	8	* Chunks are allocated as a contiguous kernel memory using gfp
	9	* allocation. This is to be used on nommu architectures.
	10	*
	11	* To use percpu-km,
	12	*
	13	* - define CONFIG_NEED_PER_CPU_KM from the arch Kconfig.
	14	*
	15	* - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK must not be defined. It's
	16	* not compatible with PER_CPU_KM. EMBED_FIRST_CHUNK should work
	17	* fine.
	18	*
	19	* - NUMA is not supported. When setting up the first chunk,
	20	* @cpu_distance_fn should be NULL or report all CPUs to be nearer
	21	* than or at LOCAL_DISTANCE.
	22	*
	23	* - It's best if the chunk size is power of two multiple of
	24	* PAGE_SIZE. Because each chunk is allocated as a contiguous
	25	* kernel memory block using alloc_pages(), memory will be wasted if
	26	* chunk size is not aligned. percpu-km code will whine about it.
	27	*/
	28
bbddff05	29	#if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
b0c9778b TH	30	#error "contiguous percpu allocation is incompatible with paged first chunk"
	31	#endif
	32
	33	#include <linux/log2.h>
	34
93274f1d DZ	35	static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
	36	int page_start, int page_end)
	37	{
	38	/* nothing */
	39	}
	40
a93ace48	41	static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
47504ee0	42	int page_start, int page_end, gfp_t gfp)
b0c9778b	43	{
b0c9778b TH	44	return 0;
	45	}
	46
a93ace48 TH	47	static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
a93ace48 TH	48	int page_start, int page_end)
b0c9778b TH	49	{
	50	/* nada */
	51	}
	52
faf65dde	53	static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
b0c9778b TH	54	{
	55	const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
	56	struct pcpu_chunk *chunk;
	57	struct page *pages;
6ab7d47b	58	unsigned long flags;
b0c9778b TH	59	int i;
b0c9778b TH	60
faf65dde	61	chunk = pcpu_alloc_chunk(gfp);
b0c9778b TH	62	if (!chunk)
	63	return NULL;
	64
554fef1c	65	pages = alloc_pages(gfp, order_base_2(nr_pages));
b0c9778b TH	66	if (!pages) {
	67	pcpu_free_chunk(chunk);
	68	return NULL;
	69	}
	70
	71	for (i = 0; i < nr_pages; i++)
	72	pcpu_set_page_chunk(nth_page(pages, i), chunk);
	73
	74	chunk->data = pages;
1b046b44	75	chunk->base_addr = page_address(pages);
a63d4ac4	76
6ab7d47b	77	spin_lock_irqsave(&pcpu_lock, flags);
b239f7da	78	pcpu_chunk_populated(chunk, 0, nr_pages);
6ab7d47b	79	spin_unlock_irqrestore(&pcpu_lock, flags);
a63d4ac4	80
30a5b536	81	pcpu_stats_chunk_alloc();
df95e795	82	trace_percpu_create_chunk(chunk->base_addr);
30a5b536	83
b0c9778b TH	84	return chunk;
	85	}
	86
	87	static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
	88	{
	89	const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
	90
e3efe3db DZ	91	if (!chunk)
	92	return;
	93
30a5b536	94	pcpu_stats_chunk_dealloc();
df95e795	95	trace_percpu_destroy_chunk(chunk->base_addr);
30a5b536	96
e3efe3db	97	if (chunk->data)
b0c9778b TH	98	__free_pages(chunk->data, order_base_2(nr_pages));
	99	pcpu_free_chunk(chunk);
	100	}
	101
	102	static struct page pcpu_addr_to_page(void addr)
	103	{
	104	return virt_to_page(addr);
	105	}
	106
	107	static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
	108	{
	109	size_t nr_pages, alloc_pages;
	110
	111	/* all units must be in a single group */
	112	if (ai->nr_groups != 1) {
870d4b12	113	pr_crit("can't handle more than one group\n");
b0c9778b TH	114	return -EINVAL;
	115	}
	116
	117	nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT;
	118	alloc_pages = roundup_pow_of_two(nr_pages);
	119
	120	if (alloc_pages > nr_pages)
870d4b12	121	pr_warn("wasting %zu pages per chunk\n",
1170532b	122	alloc_pages - nr_pages);
b0c9778b TH	123
	124	return 0;
	125	}
f1833241 RG	126
	127	static bool pcpu_should_reclaim_chunk(struct pcpu_chunk *chunk)
	128	{
	129	return false;
	130	}