path: root/kernel/dma/contiguous.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Contiguous Memory Allocator for DMA mapping framework
 * Copyright (c) 2010-2011 by Samsung Electronics.
 * Written by:
 *	Marek Szyprowski <m.szyprowski@samsung.com>
 *	Michal Nazarewicz <mina86@mina86.com>
 *
 * Contiguous Memory Allocator
 *
 *   The Contiguous Memory Allocator (CMA) makes it possible to
 *   allocate big contiguous chunks of memory after the system has
 *   booted.
 *
 * Why is it needed?
 *
 *   Various devices on embedded systems have no scatter-getter and/or
 *   IO map support and require contiguous blocks of memory to
 *   operate.  They include devices such as cameras, hardware video
 *   coders, etc.
 *
 *   Such devices often require big memory buffers (a full HD frame
 *   is, for instance, more than 2 mega pixels large, i.e. more than 6
 *   MB of memory), which makes mechanisms such as kmalloc() or
 *   alloc_page() ineffective.
 *
 *   At the same time, a solution where a big memory region is
 *   reserved for a device is suboptimal since often more memory is
 *   reserved then strictly required and, moreover, the memory is
 *   inaccessible to page system even if device drivers don't use it.
 *
 *   CMA tries to solve this issue by operating on memory regions
 *   where only movable pages can be allocated from.  This way, kernel
 *   can use the memory for pagecache and when device driver requests
 *   it, allocated pages can be migrated.
 */

#define pr_fmt(fmt) "cma: " fmt

#include <asm/page.h>

#include <linux/memblock.h>
#include <linux/err.h>
#include <linux/sizes.h>
#include <linux/dma-map-ops.h>
#include <linux/cma.h>
#include <linux/nospec.h>

#ifdef CONFIG_CMA_SIZE_MBYTES
#define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
#else
#define CMA_SIZE_MBYTES 0
#endif

static struct cma *dma_contiguous_areas[MAX_CMA_AREAS];
static unsigned int dma_contiguous_areas_num;

static int dma_contiguous_insert_area(struct cma *cma)
{
	if (dma_contiguous_areas_num >= ARRAY_SIZE(dma_contiguous_areas))
		return -EINVAL;

	dma_contiguous_areas[dma_contiguous_areas_num++] = cma;

	return 0;
}

/**
 * dma_contiguous_get_area_by_idx() - Get contiguous area at given index
 * @idx: index of the area we query
 *
 * Queries for the contiguous area located at index @idx.
 *
 * Returns:
 * A pointer to the requested contiguous area, or NULL otherwise.
 */
struct cma *dma_contiguous_get_area_by_idx(unsigned int idx)
{
	if (idx >= dma_contiguous_areas_num)
		return NULL;

	return dma_contiguous_areas[idx];
}
EXPORT_SYMBOL_GPL(dma_contiguous_get_area_by_idx);

static struct cma *dma_contiguous_default_area;

/*
 * Default global CMA area size can be defined in kernel's .config.
 * This is useful mainly for distro maintainers to create a kernel
 * that works correctly for most supported systems.
 * The size can be set in bytes or as a percentage of the total memory
 * in the system.
 *
 * Users, who want to set the size of global CMA area for their system
 * should use cma= kernel parameter.
 */
#define size_bytes ((phys_addr_t)CMA_SIZE_MBYTES * SZ_1M)
static phys_addr_t  size_cmdline __initdata = -1;
static phys_addr_t base_cmdline __initdata;
static phys_addr_t limit_cmdline __initdata;

static int __init early_cma(char *p)
{
	if (!p) {
		pr_err("Config string not provided\n");
		return -EINVAL;
	}

	size_cmdline = memparse(p, &p);
	if (*p != '@')
		return 0;
	base_cmdline = memparse(p + 1, &p);
	if (*p != '-') {
		limit_cmdline = base_cmdline + size_cmdline;
		return 0;
	}
	limit_cmdline = memparse(p + 1, &p);

	return 0;
}
early_param("cma", early_cma);

struct cma *dev_get_cma_area(struct device *dev)
{
	if (dev && dev->cma_area)
		return dev->cma_area;

	return dma_contiguous_default_area;
}
EXPORT_SYMBOL_GPL(dev_get_cma_area);

#ifdef CONFIG_DMA_NUMA_CMA

static struct cma *dma_contiguous_numa_area[MAX_NUMNODES];
static phys_addr_t numa_cma_size[MAX_NUMNODES] __initdata;
static struct cma *dma_contiguous_pernuma_area[MAX_NUMNODES];
static phys_addr_t pernuma_size_bytes __initdata;

static int __init early_numa_cma(char *p)
{
	int nid, count = 0;
	unsigned long tmp;
	char *s = p;

	while (*s) {
		if (sscanf(s, "%lu%n", &tmp, &count) != 1)
			break;

		if (s[count] == ':') {
			if (tmp >= MAX_NUMNODES)
				break;
			nid = array_index_nospec(tmp, MAX_NUMNODES);

			s += count + 1;
			tmp = memparse(s, &s);
			numa_cma_size[nid] = tmp;

			if (*s == ',')
				s++;
			else
				break;
		} else
			break;
	}

	return 0;
}
early_param("numa_cma", early_numa_cma);

static int __init early_cma_pernuma(char *p)
{
	pernuma_size_bytes = memparse(p, &p);
	return 0;
}
early_param("cma_pernuma", early_cma_pernuma);
#endif

#ifdef CONFIG_CMA_SIZE_PERCENTAGE

static phys_addr_t __init __maybe_unused cma_early_percent_memory(void)
{
	unsigned long total_pages = PHYS_PFN(memblock_phys_mem_size());

	return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
}

#else

static inline __maybe_unused phys_addr_t cma_early_percent_memory(void)
{
	return 0;
}

#endif

#ifdef CONFIG_DMA_NUMA_CMA
static void __init dma_numa_cma_reserve(void)
{
	int nid;

	for_each_node(nid) {
		int ret;
		char name[CMA_MAX_NAME];
		struct cma **cma;

		if (!node_online(nid)) {
			if (pernuma_size_bytes || numa_cma_size[nid])
				pr_warn("invalid node %d specified\n", nid);
			continue;
		}

		if (pernuma_size_bytes) {

			cma = &dma_contiguous_pernuma_area[nid];
			snprintf(name, sizeof(name), "pernuma%d", nid);
			ret = cma_declare_contiguous_nid(0, pernuma_size_bytes, 0, 0,
							 0, false, name, cma, nid);
			if (ret)
				pr_warn("%s: reservation failed: err %d, node %d", __func__,
					ret, nid);
		}

		if (numa_cma_size[nid]) {

			cma = &dma_contiguous_numa_area[nid];
			snprintf(name, sizeof(name), "numa%d", nid);
			ret = cma_declare_contiguous_nid(0, numa_cma_size[nid], 0, 0, 0, false,
							 name, cma, nid);
			if (ret)
				pr_warn("%s: reservation failed: err %d, node %d", __func__,
					ret, nid);
		}
	}
}
#else
static inline void __init dma_numa_cma_reserve(void)
{
}
#endif

/**
 * dma_contiguous_reserve() - reserve area(s) for contiguous memory handling
 * @limit: End address of the reserved memory (optional, 0 for any).
 *
 * This function reserves memory from early allocator. It should be
 * called by arch specific code once the early allocator (memblock or bootmem)
 * has been activated and all other subsystems have already allocated/reserved
 * memory.
 */
void __init dma_contiguous_reserve(phys_addr_t limit)
{
	phys_addr_t selected_size = 0;
	phys_addr_t selected_base = 0;
	phys_addr_t selected_limit = limit;
	bool fixed = false;

	dma_numa_cma_reserve();

	pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);

	if (size_cmdline != -1) {
		selected_size = size_cmdline;
		selected_base = base_cmdline;

		/* Hornor the user setup dma address limit */
		selected_limit = limit_cmdline ?: limit;

		if (base_cmdline + size_cmdline == limit_cmdline)
			fixed = true;
	} else {
#ifdef CONFIG_CMA_SIZE_SEL_MBYTES
		selected_size = size_bytes;
#elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE)
		selected_size = cma_early_percent_memory();
#elif defined(CONFIG_CMA_SIZE_SEL_MIN)
		selected_size = min(size_bytes, cma_early_percent_memory());
#elif defined(CONFIG_CMA_SIZE_SEL_MAX)
		selected_size = max(size_bytes,