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arm64/mm: Correct the cache line size warning with non coherent device

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If the cache line size is greater than ARCH_DMA_MINALIGN (128),
the warning shows and it's tainted as TAINT_CPU_OUT_OF_SPEC.

However, it's not good because as discussed in the thread [1], the cpu
cache line size will be problem only on non-coherent devices.

Since the coherent flag is already introduced to struct device,
show the warning only if the device is non-coherent device and
ARCH_DMA_MINALIGN is smaller than the cpu cache size.

[1] https://lore.kernel.org/linux-arm-kernel/20180514145703.celnlobzn3uh5tc2@localhost/

Signed-off-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Reviewed-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Tested-by: Zhang Lei <zhang.lei@jp.fujitsu.com>
[catalin.marinas@arm.com: removed 'if' block for WARN_TAINT]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Masayoshi Mizuma 2019-06-14 09:11:41 -04:00 committed by Catalin Marinas
parent 1a2a66db49
commit 8f5c9037a5
3 changed files with 16 additions and 7 deletions
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7
arch/arm64/include/asm/cache.h
View File

@ -91,6 +91,13 @@ static inline u32 cache_type_cwg(void)
#define __read_mostly __attribute__((__section__(".data..read_mostly"))) #define __read_mostly __attribute__((__section__(".data..read_mostly")))
static inline int cache_line_size_of_cpu(void)
{
u32 cwg = cache_type_cwg();
return cwg ? 4 << cwg : ARCH_DMA_MINALIGN;
}
int cache_line_size(void); int cache_line_size(void);
/* /*

4
arch/arm64/kernel/cacheinfo.c
View File

@ -30,12 +30,10 @@
int cache_line_size(void) int cache_line_size(void)
{ {
u32 cwg = cache_type_cwg();
if (coherency_max_size != 0) if (coherency_max_size != 0)
return coherency_max_size; return coherency_max_size;
return cwg ? 4 << cwg : ARCH_DMA_MINALIGN; return cache_line_size_of_cpu();
} }
EXPORT_SYMBOL_GPL(cache_line_size); EXPORT_SYMBOL_GPL(cache_line_size);

12
arch/arm64/mm/dma-mapping.c
View File

@ -91,10 +91,6 @@ static int __swiotlb_mmap_pfn(struct vm_area_struct *vma,
static int __init arm64_dma_init(void) static int __init arm64_dma_init(void)
{ {
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 dma_atomic_pool_init(GFP_DMA32, __pgprot(PROT_NORMAL_NC)); return dma_atomic_pool_init(GFP_DMA32, __pgprot(PROT_NORMAL_NC));
} }
arch_initcall(arm64_dma_init); arch_initcall(arm64_dma_init);
@ -472,6 +468,14 @@ static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
const struct iommu_ops *iommu, bool coherent) const struct iommu_ops *iommu, bool coherent)
{ {
int cls = cache_line_size_of_cpu();
WARN_TAINT(!coherent && cls > ARCH_DMA_MINALIGN,
TAINT_CPU_OUT_OF_SPEC,
"%s %s: ARCH_DMA_MINALIGN smaller than CTR_EL0.CWG (%d < %d)",
dev_driver_string(dev), dev_name(dev),
ARCH_DMA_MINALIGN, cls);
dev->dma_coherent = coherent; dev->dma_coherent = coherent;
__iommu_setup_dma_ops(dev, dma_base, size, iommu); __iommu_setup_dma_ops(dev, dma_base, size, iommu);