ARM: 6535/1: V6 MPCore v6_dma_inv_range and v6_dma_flush_range RWFO fix

Cache ownership must be acquired by reading/writing data from the
cache line to make cache operation have the desired effect on the
SMP MPCore CPU. However, the ownership is never acquired in the
v6_dma_inv_range function when cleaning the first line and
flushing the last one, in case the address is not aligned
to D_CACHE_LINE_SIZE boundary.
Fix this by reading/writing data if needed, before performing
cache operations.
While at it, fix v6_dma_flush_range to prevent RWFO outside
the buffer.

Cc: stable@kernel.org
Signed-off-by: Valentine Barshak <vbarshak@mvista.com>
Signed-off-by: George G. Davis <gdavis@mvista.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 20 insertions, 8 deletions

diff --git a/arch/arm/mm/cache-v6.S b/arch/arm/mm/cache-v6.S
index 99fa688dfadd..c96fa1b3f49f 100644
--- a/arch/arm/mm/cache-v6.S
+++ b/arch/arm/mm/cache-v6.S
@@ -203,6 +203,10 @@ ENTRY(v6_flush_kern_dcache_area)
  *      - end     - virtual end address of region
  */
 v6_dma_inv_range:
+#ifdef CONFIG_DMA_CACHE_RWFO
+        ldrb    r2, [r0]                        @ read for ownership
+        strb    r2, [r0]                        @ write for ownership
+#endif
         tst     r0, #D_CACHE_LINE_SIZE - 1
         bic     r0, r0, #D_CACHE_LINE_SIZE - 1
 #ifdef HARVARD_CACHE
@@ -211,6 +215,10 @@ v6_dma_inv_range:
         mcrne   p15, 0, r0, c7, c11, 1          @ clean unified line
 #endif
         tst     r1, #D_CACHE_LINE_SIZE - 1
+#ifdef CONFIG_DMA_CACHE_RWFO
+        ldrneb  r2, [r1, #-1]                   @ read for ownership
+        strneb  r2, [r1, #-1]                   @ write for ownership
+#endif
         bic     r1, r1, #D_CACHE_LINE_SIZE - 1
 #ifdef HARVARD_CACHE
         mcrne   p15, 0, r1, c7, c14, 1          @ clean & invalidate D line
@@ -218,10 +226,6 @@ v6_dma_inv_range:
         mcrne   p15, 0, r1, c7, c15, 1          @ clean & invalidate unified line
 #endif
 1:
-#ifdef CONFIG_DMA_CACHE_RWFO
-        ldr     r2, [r0]                        @ read for ownership
-        str     r2, [r0]                        @ write for ownership
-#endif
 #ifdef HARVARD_CACHE
         mcr     p15, 0, r0, c7, c6, 1           @ invalidate D line
 #else
@@ -229,6 +233,10 @@ v6_dma_inv_range:
 #endif
         add     r0, r0, #D_CACHE_LINE_SIZE
         cmp     r0, r1
+#ifdef CONFIG_DMA_CACHE_RWFO
+        ldrlo   r2, [r0]                        @ read for ownership
+        strlo   r2, [r0]                        @ write for ownership
+#endif
         blo     1b
         mov     r0, #0
         mcr     p15, 0, r0, c7, c10, 4          @ drain write buffer
@@ -263,12 +271,12 @@ v6_dma_clean_range:
  *      - end     - virtual end address of region
  */
 ENTRY(v6_dma_flush_range)
-        bic     r0, r0, #D_CACHE_LINE_SIZE - 1
-1:
 #ifdef CONFIG_DMA_CACHE_RWFO
-        ldr     r2, [r0]                        @ read for ownership
-        str     r2, [r0]                        @ write for ownership
+        ldrb    r2, [r0]                @ read for ownership
+        strb    r2, [r0]                @ write for ownership
 #endif
+        bic     r0, r0, #D_CACHE_LINE_SIZE - 1
+1:
 #ifdef HARVARD_CACHE
         mcr     p15, 0, r0, c7, c14, 1          @ clean & invalidate D line
 #else
@@ -276,6 +284,10 @@ ENTRY(v6_dma_flush_range)
 #endif
         add     r0, r0, #D_CACHE_LINE_SIZE
         cmp     r0, r1
+#ifdef CONFIG_DMA_CACHE_RWFO
+        ldrlob  r2, [r0]                        @ read for ownership
+        strlob  r2, [r0]                        @ write for ownership
+#endif
         blo     1b
         mov     r0, #0
         mcr     p15, 0, r0, c7, c10, 4          @ drain write buffer