diff options
Diffstat (limited to '0106-arm64-mm-Don-t-invalidate-FROM_DEVICE-buffers-at-sta.patch')
| -rw-r--r-- | 0106-arm64-mm-Don-t-invalidate-FROM_DEVICE-buffers-at-sta.patch | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/0106-arm64-mm-Don-t-invalidate-FROM_DEVICE-buffers-at-sta.patch b/0106-arm64-mm-Don-t-invalidate-FROM_DEVICE-buffers-at-sta.patch new file mode 100644 index 000000000000..a803b1f45a97 --- /dev/null +++ b/0106-arm64-mm-Don-t-invalidate-FROM_DEVICE-buffers-at-sta.patch @@ -0,0 +1,57 @@ +From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 +From: Will Deacon <will@kernel.org> +Date: Fri, 10 Jun 2022 16:12:27 +0100 +Subject: [PATCH] arm64: mm: Don't invalidate FROM_DEVICE buffers at start of + DMA transfer + +commit c50f11c6196f45c92ca48b16a5071615d4ae0572 upstream. + +Invalidating the buffer memory in arch_sync_dma_for_device() for +FROM_DEVICE transfers + +When using the streaming DMA API to map a buffer prior to inbound +non-coherent DMA (i.e. DMA_FROM_DEVICE), we invalidate any dirty CPU +cachelines so that they will not be written back during the transfer and +corrupt the buffer contents written by the DMA. This, however, poses two +potential problems: + + (1) If the DMA transfer does not write to every byte in the buffer, + then the unwritten bytes will contain stale data once the transfer + has completed. + + (2) If the buffer has a virtual alias in userspace, then stale data + may be visible via this alias during the period between performing + the cache invalidation and the DMA writes landing in memory. + +Address both of these issues by cleaning (aka writing-back) the dirty +lines in arch_sync_dma_for_device(DMA_FROM_DEVICE) instead of discarding +them using invalidation. + +Cc: Ard Biesheuvel <ardb@kernel.org> +Cc: Christoph Hellwig <hch@lst.de> +Cc: Robin Murphy <robin.murphy@arm.com> +Cc: Russell King <linux@armlinux.org.uk> +Cc: <stable@vger.kernel.org> +Link: https://lore.kernel.org/r/20220606152150.GA31568@willie-the-truck +Signed-off-by: Will Deacon <will@kernel.org> +Reviewed-by: Ard Biesheuvel <ardb@kernel.org> +Link: https://lore.kernel.org/r/20220610151228.4562-2-will@kernel.org +Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +--- + arch/arm64/mm/cache.S | 2 -- + 1 file changed, 2 deletions(-) + +diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S +index 0ea6cc25dc66356de86d262cc3d48bb993ec3cd0..21c907987080f60d4b25ef70f438332a6c1c24cc 100644 +--- a/arch/arm64/mm/cache.S ++++ b/arch/arm64/mm/cache.S +@@ -218,8 +218,6 @@ SYM_FUNC_ALIAS(__dma_flush_area, __pi___dma_flush_area) + */ + SYM_FUNC_START(__pi___dma_map_area) + add x1, x0, x1 +- cmp w2, #DMA_FROM_DEVICE +- b.eq __pi_dcache_inval_poc + b __pi_dcache_clean_poc + SYM_FUNC_END(__pi___dma_map_area) + SYM_FUNC_ALIAS(__dma_map_area, __pi___dma_map_area) |