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// SPDX-License-Identifier: GPL-2.0
/*
* DMA operations that map physical memory directly without using an IOMMU or
* flushing caches.
*/
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/dma-direct.h>
#include <linux/scatterlist.h>
#include <linux/dma-contiguous.h>
#include <linux/pfn.h>
#include <linux/set_memory.h>
#define DIRECT_MAPPING_ERROR 0
/*
* Most architectures use ZONE_DMA for the first 16 Megabytes, but
* some use it for entirely different regions:
*/
#ifndef ARCH_ZONE_DMA_BITS
#define ARCH_ZONE_DMA_BITS 24
#endif
/*
* For AMD SEV all DMA must be to unencrypted addresses.
*/
static inline bool force_dma_unencrypted(void)
{
return sev_active();
}
static bool
check_addr(struct device *dev, dma_addr_t dma_addr, size_t size,
const char *caller)
{
if (unlikely(dev && !dma_capable(dev, dma_addr, size))) {
if (*dev->dma_mask >= DMA_BIT_MASK(32)) {
dev_err(dev,
"%s: overflow %pad+%zu of device mask %llx\n",
caller, &dma_addr, size, *dev->dma_mask);
}
return false;
}
return true;
}
static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
{
dma_addr_t addr = force_dma_unencrypted() ?
__phys_to_dma(dev, phys) : phys_to_dma(dev, phys);
return addr + size - 1 <= dev->coherent_dma_mask;
}
void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
gfp_t gfp, unsigned long attrs)
{
unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
int page_order = get_order(size);
struct page *page = NULL;
void *ret;
/* we always manually zero the memory once we are done: */
gfp &= ~__GFP_ZERO;
/* GFP_DMA32 and GFP_DMA are no ops without the corresponding zones: */
if (dev->coherent_dma_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
gfp |= GFP_DMA;
if (dev->coherent_dma_mask <= DMA_BIT_MASK(32) && !(gfp & GFP_DMA))
gfp |= GFP_DMA32;
again:
/* CMA can be used only in the context which permits sleeping */
if (gfpflags_allow_blocking(gfp)) {
page = dma_alloc_from_contiguous(dev, count, page_order, gfp);
if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
dma_release_from_contiguous(dev, page, count);
page = NULL;
}
}
if (!page)
page = alloc_pages_node(dev_to_node(dev), gfp, page_order);
if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
__free_pages(page, page_order);
page = NULL;
if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
dev->coherent_dma_mask < DMA_BIT_MASK(64) &&
!(gfp & (GFP_DMA32 | GFP_DMA))) {
gfp |= GFP_DMA32;
goto again;
}
if (IS_ENABLED(CONFIG_ZONE_DMA) &&
dev->coherent_dma_mask < DMA_BIT_MASK(32) &&
!(gfp & GFP_DMA)) {
gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
goto again;
}
}
if (!page)
return NULL;
ret = page_address(page);
if (force_dma_unencrypted()) {
set_memory_decrypted((unsigned long)ret, 1 << page_order);
*dma_handle = __phys_to_dma(dev, page_to_phys(page));
} else {
*dma_handle = phys_to_dma(dev, page_to_phys(page));
}
memset(ret, 0, size);
return ret;
}
/*
* NOTE: this function must never look at the dma_addr argument, because we want
* to be able to use it as a helper for iommu implementations as well.
*/
void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,
dma_addr_t dma_addr, unsigned long attrs)
{
unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
unsigned int page_order = get_order(size);
if (force_dma_unencrypted())
set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);
if (!dma_release_from_contiguous(dev, virt_to_page(cpu_addr), count))
free_pages((unsigned long)cpu_addr, page_order);
}
static dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size, enum dma_data_direction dir,
unsigned long attrs)
{
dma_addr_t dma_addr = phys_to_dma(dev, page_to_phys(page)) + offset;
if (!check_addr(dev, dma_addr, size, __func__))
return DIRECT_MAPPING_ERROR;
return dma_addr;
}
static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
int nents, enum dma_data_direction dir, unsigned long attrs)
{
int i;
struct scatterlist *sg;
for_each_sg(sgl, sg, nents, i) {
BUG_ON(!sg_page(sg));
sg_dma_address(sg) = phys_to_dma(dev, sg_phys(sg));
if (!check_addr(dev, sg_dma_address(sg), sg->length, __func__))
return 0;
sg_dma_len(sg) = sg->length;
}
return nents;
}
int dma_direct_supported(struct device *dev, u64 mask)
{
#ifdef CONFIG_ZONE_DMA
if (mask < DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
return 0;
#else
/*
* Because 32-bit DMA masks are so common we expect every architecture
* to be able to satisfy them - either by not supporting more physical
* memory, or by providing a ZONE_DMA32. If neither is the case, the
* architecture needs to use an IOMMU instead of the direct mapping.
*/
if (mask < DMA_BIT_MASK(32))
return 0;
#endif
return 1;
}
static int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr)
{
return dma_addr == DIRECT_MAPPING_ERROR;
}
const struct dma_map_ops dma_direct_ops = {
.alloc = dma_direct_alloc,
.free = dma_direct_free,
.map_page = dma_direct_map_page,
.map_sg = dma_direct_map_sg,
.dma_supported = dma_direct_supported,
.mapping_error = dma_direct_mapping_error,
};
EXPORT_SYMBOL(dma_direct_ops);
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