From 7ae04ba36b381bffe2471eff3a93edced843240f Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Sat, 27 Jul 2024 20:22:52 +0200
Subject: [PATCH] parisc: fix a possible DMA corruption
ARCH_DMA_MINALIGN was defined as 16 - this is too small - it may be
possible that two unrelated 16-byte allocations share a cache line. If
one of these allocations is written using DMA and the other is written
using cached write, the value that was written with DMA may be
corrupted.
This commit changes ARCH_DMA_MINALIGN to be 128 on PA20 and 32 on PA1.1 -
that's the largest possible cache line size.
As different parisc microarchitectures have different cache line size, we
define arch_slab_minalign(), cache_line_size() and
dma_get_cache_alignment() so that the kernel may tune slab cache
parameters dynamically, based on the detected cache line size.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Helge Deller <deller@gmx.de>
---
arch/parisc/Kconfig | 1 +
arch/parisc/include/asm/cache.h | 11 ++++++++++-
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 5d650e02cbf4a..b0a2ac3ba9161 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -20,6 +20,7 @@ config PARISC
select ARCH_SUPPORTS_HUGETLBFS if PA20
select ARCH_SUPPORTS_MEMORY_FAILURE
select ARCH_STACKWALK
+ select ARCH_HAS_CACHE_LINE_SIZE
select ARCH_HAS_DEBUG_VM_PGTABLE
select HAVE_RELIABLE_STACKTRACE
select DMA_OPS
diff --git a/arch/parisc/include/asm/cache.h b/arch/parisc/include/asm/cache.h
index 2a60d7a72f1fa..a3f0f100f2194 100644
--- a/arch/parisc/include/asm/cache.h
+++ b/arch/parisc/include/asm/cache.h
@@ -20,7 +20,16 @@
#define SMP_CACHE_BYTES L1_CACHE_BYTES
-#define ARCH_DMA_MINALIGN L1_CACHE_BYTES
+#ifdef CONFIG_PA20
+#define ARCH_DMA_MINALIGN 128
+#else
+#define ARCH_DMA_MINALIGN 32
+#endif
+#define ARCH_KMALLOC_MINALIGN 16 /* ldcw requires 16-byte alignment */
+
+#define arch_slab_minalign() ((unsigned)dcache_stride)
+#define cache_line_size() dcache_stride
+#define dma_get_cache_alignment cache_line_size
#define __read_mostly __section(".data..read_mostly")
--
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