target/arm/translate-a64: Don't underdecode PRFM

The PRFM prefetch insn in the load/store with imm9 encodings
requires idx field 0b00; we were underdecoding this by
only checking !is_unpriv (which is equivalent to idx != 2).
Correctly UNDEF the unallocated encodings where idx == 0b01
and 0b11 as well as 0b10.

Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Message-id: 20190125182626.9221-3-peter.maydell@linaro.org

diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index e6df303e3212a815ddec09a2d6977b75fe97053e..8e081758e03d85d277560a4ccafe85d8911b8720 100644 (file)
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -2803,7 +2803,7 @@ static void disas_ldst_reg_imm9(DisasContext *s, uint32_t insn,
     } else {
         if (size == 3 && opc == 2) {
             /* PRFM - prefetch */
-            if (is_unpriv) {
+            if (idx != 0) {
                 unallocated_encoding(s);
                 return;
             }