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, 4 insertions, 13 deletions

diff --git a/exec.c b/exec.c
index e4652c0e75..53a15b7ad7 100644
--- a/exec.c
+++ b/exec.c
@@ -3363,14 +3363,9 @@ static MemTxResult flatview_write_continue(FlatView *fv, hwaddr addr,
             l = memory_access_size(mr, l, addr1);
             /* XXX: could force current_cpu to NULL to avoid
                potential bugs */
-            val = ldn_p(buf, l);
-            /*
-             * TODO: Merge bswap from ldn_p into memory_region_dispatch_write
-             * by using ldn_he_p and dropping MO_TE to get a host-endian value.
-             */
+            val = ldn_he_p(buf, l);
             result |= memory_region_dispatch_write(mr, addr1, val,
-                                                   size_memop(l) | MO_TE,
-                                                   attrs);
+                                                   size_memop(l), attrs);
         } else {
             /* RAM case */
             ptr = qemu_ram_ptr_length(mr->ram_block, addr1, &l, false);
@@ -3431,13 +3426,9 @@ MemTxResult flatview_read_continue(FlatView *fv, hwaddr addr,
             /* I/O case */
             release_lock |= prepare_mmio_access(mr);
             l = memory_access_size(mr, l, addr1);
-            /*
-             * TODO: Merge bswap from stn_p into memory_region_dispatch_read
-             * by using stn_he_p and dropping MO_TE to get a host-endian value.
-             */
             result |= memory_region_dispatch_read(mr, addr1, &val,
-                                                  size_memop(l) | MO_TE, attrs);
-            stn_p(buf, l, val);
+                                                  size_memop(l), attrs);
+            stn_he_p(buf, l, val);
         } else {
             /* RAM case */
             ptr = qemu_ram_ptr_length(mr->ram_block, addr1, &l, false);