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authorChristoph Hellwig <hch@lst.de>2018-08-16 15:30:39 +0300
committerChristoph Hellwig <hch@lst.de>2018-10-19 08:43:46 +0200
commitdff8d6c1ed584de65aac40494d3e7468c50980c3 (patch)
tree998f71d7b0951479f511df2ac236eaf850120a06 /kernel/dma
parent8088546832aa2c0d8f99dd56edf6384f8a9b63b3 (diff)
downloadlinux-dff8d6c1ed584de65aac40494d3e7468c50980c3.tar.bz2
swiotlb: remove the overflow buffer
Like all other dma mapping drivers just return an error code instead of an actual memory buffer. The reason for the overflow buffer was that at the time swiotlb was invented there was no way to check for dma mapping errors, but this has long been fixed. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'kernel/dma')
-rw-r--r--kernel/dma/direct.c2
-rw-r--r--kernel/dma/swiotlb.c59
2 files changed, 3 insertions, 58 deletions
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 87a6bc2a96c0..f14c376937e5 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -14,8 +14,6 @@
#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:
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 69bf305ee5f8..11dbcd80b4a6 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -73,13 +73,6 @@ static phys_addr_t io_tlb_start, io_tlb_end;
static unsigned long io_tlb_nslabs;
/*
- * When the IOMMU overflows we return a fallback buffer. This sets the size.
- */
-static unsigned long io_tlb_overflow = 32*1024;
-
-static phys_addr_t io_tlb_overflow_buffer;
-
-/*
* This is a free list describing the number of free entries available from
* each index
*/
@@ -126,7 +119,6 @@ setup_io_tlb_npages(char *str)
return 0;
}
early_param("swiotlb", setup_io_tlb_npages);
-/* make io_tlb_overflow tunable too? */
unsigned long swiotlb_nr_tbl(void)
{
@@ -194,16 +186,10 @@ void __init swiotlb_update_mem_attributes(void)
bytes = PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT);
set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
memset(vaddr, 0, bytes);
-
- vaddr = phys_to_virt(io_tlb_overflow_buffer);
- bytes = PAGE_ALIGN(io_tlb_overflow);
- set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
- memset(vaddr, 0, bytes);
}
int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
{
- void *v_overflow_buffer;
unsigned long i, bytes;
bytes = nslabs << IO_TLB_SHIFT;
@@ -213,17 +199,6 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
io_tlb_end = io_tlb_start + bytes;
/*
- * Get the overflow emergency buffer
- */
- v_overflow_buffer = memblock_virt_alloc_low_nopanic(
- PAGE_ALIGN(io_tlb_overflow),
- PAGE_SIZE);
- if (!v_overflow_buffer)
- return -ENOMEM;
-
- io_tlb_overflow_buffer = __pa(v_overflow_buffer);
-
- /*
* Allocate and initialize the free list array. This array is used
* to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
* between io_tlb_start and io_tlb_end.
@@ -330,7 +305,6 @@ int
swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
{
unsigned long i, bytes;
- unsigned char *v_overflow_buffer;
bytes = nslabs << IO_TLB_SHIFT;
@@ -342,19 +316,6 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
memset(tlb, 0, bytes);
/*
- * Get the overflow emergency buffer
- */
- v_overflow_buffer = (void *)__get_free_pages(GFP_DMA,
- get_order(io_tlb_overflow));
- if (!v_overflow_buffer)
- goto cleanup2;
-
- set_memory_decrypted((unsigned long)v_overflow_buffer,
- io_tlb_overflow >> PAGE_SHIFT);
- memset(v_overflow_buffer, 0, io_tlb_overflow);
- io_tlb_overflow_buffer = virt_to_phys(v_overflow_buffer);
-
- /*
* Allocate and initialize the free list array. This array is used
* to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
* between io_tlb_start and io_tlb_end.
@@ -390,10 +351,6 @@ cleanup4:
sizeof(int)));
io_tlb_list = NULL;
cleanup3:
- free_pages((unsigned long)v_overflow_buffer,
- get_order(io_tlb_overflow));
- io_tlb_overflow_buffer = 0;
-cleanup2:
io_tlb_end = 0;
io_tlb_start = 0;
io_tlb_nslabs = 0;
@@ -407,8 +364,6 @@ void __init swiotlb_exit(void)
return;
if (late_alloc) {
- free_pages((unsigned long)phys_to_virt(io_tlb_overflow_buffer),
- get_order(io_tlb_overflow));
free_pages((unsigned long)io_tlb_orig_addr,
get_order(io_tlb_nslabs * sizeof(phys_addr_t)));
free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
@@ -416,8 +371,6 @@ void __init swiotlb_exit(void)
free_pages((unsigned long)phys_to_virt(io_tlb_start),
get_order(io_tlb_nslabs << IO_TLB_SHIFT));
} else {
- memblock_free_late(io_tlb_overflow_buffer,
- PAGE_ALIGN(io_tlb_overflow));
memblock_free_late(__pa(io_tlb_orig_addr),
PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
memblock_free_late(__pa(io_tlb_list),
@@ -790,7 +743,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
/* Oh well, have to allocate and map a bounce buffer. */
map = map_single(dev, phys, size, dir, attrs);
if (map == SWIOTLB_MAP_ERROR)
- return __phys_to_dma(dev, io_tlb_overflow_buffer);
+ return DIRECT_MAPPING_ERROR;
dev_addr = __phys_to_dma(dev, map);
@@ -801,7 +754,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
attrs |= DMA_ATTR_SKIP_CPU_SYNC;
swiotlb_tbl_unmap_single(dev, map, size, dir, attrs);
- return __phys_to_dma(dev, io_tlb_overflow_buffer);
+ return DIRECT_MAPPING_ERROR;
}
/*
@@ -985,12 +938,6 @@ swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE);
}
-int
-swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
-{
- return (dma_addr == __phys_to_dma(hwdev, io_tlb_overflow_buffer));
-}
-
/*
* Return whether the given device DMA address mask can be supported
* properly. For example, if your device can only drive the low 24-bits
@@ -1033,7 +980,7 @@ void swiotlb_free(struct device *dev, size_t size, void *vaddr,
}
const struct dma_map_ops swiotlb_dma_ops = {
- .mapping_error = swiotlb_dma_mapping_error,
+ .mapping_error = dma_direct_mapping_error,
.alloc = swiotlb_alloc,
.free = swiotlb_free,
.sync_single_for_cpu = swiotlb_sync_single_for_cpu,