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arm64: Increase ARCH_DMA_MINALIGN to 128 

This patch increases the ARCH_DMA_MINALIGN to 128 so that it covers the
currently known Cache Writeback Granule (CTR_EL0.CWG) on arm64 and moves
the fallback in cache_line_size() from L1_CACHE_BYTES to this constant.
In addition, it warns (and taints) if the CWG is larger than
ARCH_DMA_MINALIGN as this is not safe with non-coherent DMA.

Cc: Will Deacon <will.deacon@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Catalin Marinas 2018-05-11 13:33:12 +01:00
parent d93277b983
commit ebc7e21e0f
3 changed files with 9 additions and 9 deletions
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4
arch/arm64/include/asm/cache.h
View File

@ -43,7 +43,7 @@
* cache before the transfer is done, causing old data to be seen by
* the CPU.
*/
#define ARCH_DMA_MINALIGN L1_CACHE_BYTES
#define ARCH_DMA_MINALIGN (128)
#ifndef __ASSEMBLY__
@ -77,7 +77,7 @@ static inline u32 cache_type_cwg(void)
static inline int cache_line_size(void)
{
u32 cwg = cache_type_cwg();
return cwg ? 4 << cwg : L1_CACHE_BYTES;
return cwg ? 4 << cwg : ARCH_DMA_MINALIGN;
}
#endif /* __ASSEMBLY__ */

9
arch/arm64/kernel/cpufeature.c
View File

@ -1606,7 +1606,6 @@ static void __init setup_system_capabilities(void)
void __init setup_cpu_features(void)
{
u32 cwg;
int cls;
setup_system_capabilities();
mark_const_caps_ready();
@ -1627,13 +1626,9 @@ void __init setup_cpu_features(void)
* Check for sane CTR_EL0.CWG value.
*/
cwg = cache_type_cwg();
cls = cache_line_size();
if (!cwg)
pr_warn("No Cache Writeback Granule information, assuming cache line size %d\n",
cls);
if (L1_CACHE_BYTES < cls)
pr_warn("L1_CACHE_BYTES smaller than the Cache Writeback Granule (%d < %d)\n",
L1_CACHE_BYTES, cls);
pr_warn("No Cache Writeback Granule information, assuming %d\n",
ARCH_DMA_MINALIGN);
}
static bool __maybe_unused

5
arch/arm64/mm/dma-mapping.c
View File

@ -504,6 +504,11 @@ static int __init arm64_dma_init(void)
max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT))
swiotlb = 1;
WARN_TAINT(ARCH_DMA_MINALIGN < cache_line_size(),
TAINT_CPU_OUT_OF_SPEC,
"ARCH_DMA_MINALIGN smaller than CTR_EL0.CWG (%d < %d)",
ARCH_DMA_MINALIGN, cache_line_size());
return atomic_pool_init();
}
arch_initcall(arm64_dma_init);