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|
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2018 Christoph Hellwig.
*
* DMA operations that map physical memory directly without using an IOMMU.
*/
#include <linux/memblock.h> /* for max_pfn */
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/dma-direct.h>
#include <linux/scatterlist.h>
#include <linux/dma-contiguous.h>
#include <linux/dma-noncoherent.h>
#include <linux/pfn.h>
#include <linux/vmalloc.h>
#include <linux/set_memory.h>
#include <linux/swiotlb.h>
/*
* Most architectures use ZONE_DMA for the first 16 Megabytes, but some use it
* it for entirely different regions. In that case the arch code needs to
* override the variable below for dma-direct to work properly.
*/
unsigned int zone_dma_bits __ro_after_init = 24;
static inline dma_addr_t phys_to_dma_direct(struct device *dev,
phys_addr_t phys)
{
if (force_dma_unencrypted(dev))
return __phys_to_dma(dev, phys);
return phys_to_dma(dev, phys);
}
static inline struct page *dma_direct_to_page(struct device *dev,
dma_addr_t dma_addr)
{
return pfn_to_page(PHYS_PFN(dma_to_phys(dev, dma_addr)));
}
u64 dma_direct_get_required_mask(struct device *dev)
{
phys_addr_t phys = (phys_addr_t)(max_pfn - 1) << PAGE_SHIFT;
u64 max_dma = phys_to_dma_direct(dev, phys);
return (1ULL << (fls64(max_dma) - 1)) * 2 - 1;
}
static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
u64 *phys_limit)
{
u64 dma_limit = min_not_zero(dma_mask, dev->bus_dma_limit);
if (force_dma_unencrypted(dev))
*phys_limit = __dma_to_phys(dev, dma_limit);
else
*phys_limit = dma_to_phys(dev, dma_limit);
/*
* Optimistically try the zone that the physical address mask falls
* into first. If that returns memory that isn't actually addressable
* we will fallback to the next lower zone and try again.
*
* Note that GFP_DMA32 and GFP_DMA are no ops without the corresponding
* zones.
*/
if (*phys_limit <= DMA_BIT_MASK(zone_dma_bits))
return GFP_DMA;
if (*phys_limit <= DMA_BIT_MASK(32))
return GFP_DMA32;
return 0;
}
static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
{
return phys_to_dma_direct(dev, phys) + size - 1 <=
min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit);
}
struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
gfp_t gfp, unsigned long attrs)
{
size_t alloc_size = PAGE_ALIGN(size);
int node = dev_to_node(dev);
struct page *page = NULL;
u64 phys_limit;
if (attrs & DMA_ATTR_NO_WARN)
gfp |= __GFP_NOWARN;
/* we always manually zero the memory once we are done: */
gfp &= ~__GFP_ZERO;
gfp |= __dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
&phys_limit);
page = dma_alloc_contiguous(dev, alloc_size, gfp);
if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
dma_free_contiguous(dev, page, alloc_size);
page = NULL;
}
again:
if (!page)
page = alloc_pages_node(node, gfp, get_order(alloc_size));
if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
dma_free_contiguous(dev, page, size);
page = NULL;
if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
phys_limit < DMA_BIT_MASK(64) &&
!(gfp & (GFP_DMA32 | GFP_DMA))) {
gfp |= GFP_DMA32;
goto again;
}
if (IS_ENABLED(CONFIG_ZONE_DMA) && !(gfp & GFP_DMA)) {
gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
goto again;
}
}
return page;
}
void *dma_direct_alloc_pages(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
{
struct page *page;
void *ret;
if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
dma_alloc_need_uncached(dev, attrs) &&
!gfpflags_allow_blocking(gfp)) {
ret = dma_alloc_from_pool(PAGE_ALIGN(size), &page, gfp);
if (!ret)
return NULL;
goto done;
}
page = __dma_direct_alloc_pages(dev, size, gfp, attrs);
if (!page)
return NULL;
if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
!force_dma_unencrypted(dev)) {
/* remove any dirty cache lines on the kernel alias */
if (!PageHighMem(page))
arch_dma_prep_coherent(page, size);
/* return the page pointer as the opaque cookie */
ret = page;
goto done;
}
if ((IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
dma_alloc_need_uncached(dev, attrs)) ||
(IS_ENABLED(CONFIG_DMA_REMAP) && PageHighMem(page))) {
/* remove any dirty cache lines on the kernel alias */
arch_dma_prep_coherent(page, PAGE_ALIGN(size));
/* create a coherent mapping */
ret = dma_common_contiguous_remap(page, PAGE_ALIGN(size),
dma_pgprot(dev, PAGE_KERNEL, attrs),
__builtin_return_address(0));
if (!ret)
goto out_free_pages;
memset(ret, 0, size);
goto done;
}
if (PageHighMem(page)) {
/*
* Depending on the cma= arguments and per-arch setup
* dma_alloc_contiguous could return highmem pages.
* Without remapping there is no way to return them here,
* so log an error and fail.
*/
dev_info(dev, "Rejecting highmem page from CMA.\n");
goto out_free_pages;
}
ret = page_address(page);
if (force_dma_unencrypted(dev))
set_memory_decrypted((unsigned long)ret, 1 << get_order(size));
memset(ret, 0, size);
if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
dma_alloc_need_uncached(dev, attrs)) {
arch_dma_prep_coherent(page, size);
ret = arch_dma_set_uncached(ret, size);
if (IS_ERR(ret))
goto out_free_pages;
}
done:
if (force_dma_unencrypted(dev))
*dma_handle = __phys_to_dma(dev, page_to_phys(page));
else
*dma_handle = phys_to_dma(dev, page_to_phys(page));
return ret;
out_free_pages:
dma_free_contiguous(dev, page, size);
return NULL;
}
void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
dma_addr_t dma_addr, unsigned long attrs)
{
unsigned int page_order = get_order(size);
if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
!force_dma_unencrypted(dev)) {
/* cpu_addr is a struct page cookie, not a kernel address */
dma_free_contiguous(dev, cpu_addr, size);
return;
}
if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
dma_free_from_pool(cpu_addr, PAGE_ALIGN(size)))
return;
if (force_dma_unencrypted(dev))
set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);
if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr))
vunmap(cpu_addr);
else if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED))
arch_dma_clear_uncached(cpu_addr, size);
dma_free_contiguous(dev
|