memory: Single byte swap along the I/O path

Now that MemOp has been pushed down into the memory API, and
callers are encoding endianness, we can collapse byte swaps
along the I/O path into the accelerator and target independent
adjust_endianness.

Collapsing byte swaps along the I/O path enables additional endian
inversion logic, e.g. SPARC64 Invert Endian TTE bit, with redundant
byte swaps cancelling out.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Tony Nguyen <tony.nguyen@bt.com>
Message-Id: <911ff31af11922a9afba9b7ce128af8b8b80f316.1566466906.git.tony.nguyen@bt.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 12 insertions, 21 deletions

diff --git a/memory.c b/memory.c
index d72143a18f..7cdf4fe556 100644
--- a/memory.c
+++ b/memory.c
@@ -351,32 +351,23 @@ static bool memory_region_big_endian(MemoryRegion *mr)
 #endif
 }
 
-static bool memory_region_wrong_endianness(MemoryRegion *mr)
+static void adjust_endianness(MemoryRegion *mr, uint64_t *data, MemOp op)
 {
-#ifdef TARGET_WORDS_BIGENDIAN
-    return mr->ops->endianness == DEVICE_LITTLE_ENDIAN;
-#else
-    return mr->ops->endianness == DEVICE_BIG_ENDIAN;
-#endif
-}
-
-static void adjust_endianness(MemoryRegion *mr, uint64_t *data, unsigned size)
-{
-    if (memory_region_wrong_endianness(mr)) {
-        switch (size) {
-        case 1:
+    if ((op & MO_BSWAP) != devend_memop(mr->ops->endianness)) {
+        switch (op & MO_SIZE) {
+        case MO_8:
             break;
-        case 2:
+        case MO_16:
             *data = bswap16(*data);
             break;
-        case 4:
+        case MO_32:
             *data = bswap32(*data);
             break;
-        case 8:
+        case MO_64:
             *data = bswap64(*data);
             break;
         default:
-            abort();
+            g_assert_not_reached();
         }
     }
 }
@@ -1458,7 +1449,7 @@ MemTxResult memory_region_dispatch_read(MemoryRegion *mr,
     }
 
     r = memory_region_dispatch_read1(mr, addr, pval, size, attrs);
-    adjust_endianness(mr, pval, size);
+    adjust_endianness(mr, pval, op);
     return r;
 }
 
@@ -1501,7 +1492,7 @@ MemTxResult memory_region_dispatch_write(MemoryRegion *mr,
         return MEMTX_DECODE_ERROR;
     }
 
-    adjust_endianness(mr, &data, size);
+    adjust_endianness(mr, &data, op);
 
     if ((!kvm_eventfds_enabled()) &&
         memory_region_dispatch_write_eventfds(mr, addr, data, size, attrs)) {
@@ -2350,7 +2341,7 @@ void memory_region_add_eventfd(MemoryRegion *mr,
     }
 
     if (size) {
-        adjust_endianness(mr, &mrfd.data, size);
+        adjust_endianness(mr, &mrfd.data, size_memop(size) | MO_TE);
     }
     memory_region_transaction_begin();
     for (i = 0; i < mr->ioeventfd_nb; ++i) {
@@ -2385,7 +2376,7 @@ void memory_region_del_eventfd(MemoryRegion *mr,
     unsigned i;
 
     if (size) {
-        adjust_endianness(mr, &mrfd.data, size);
+        adjust_endianness(mr, &mrfd.data, size_memop(size) | MO_TE);
     }
     memory_region_transaction_begin();
     for (i = 0; i < mr->ioeventfd_nb; ++i) {