When changing modes via SAM, we raise a specification exception if the
new PC is out of range.  The masking in s390x_tr_init_disas_context
was too late to be correct, but may be removed.  Add a debugging
assert in cpu_get_tb_cpu_state.

Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/s390x/cpu.c           | 6 ++++++
 target/s390x/tcg/translate.c | 6 +-----
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c
index 2bbeaca36e..c786767bd1 100644
--- a/target/s390x/cpu.c
+++ b/target/s390x/cpu.c
@@ -358,6 +358,12 @@ void cpu_get_tb_cpu_state(CPUS390XState *env, vaddr *pc,
         flags |= FLAG_MASK_VECTOR;
     }
     *pflags = flags;
+
+    if (!(flags & FLAG_MASK_32)) {
+        tcg_debug_assert(*pc <= 0x00ffffff);
+    } else if (!(flags & FLAG_MASK_64)) {
+        tcg_debug_assert(*pc <= 0x7fffffff);
+    }
 }
 
 static const TCGCPUOps s390_tcg_ops = {
diff --git a/target/s390x/tcg/translate.c b/target/s390x/tcg/translate.c
index 3014cbea4f..0ee14484d0 100644
--- a/target/s390x/tcg/translate.c
+++ b/target/s390x/tcg/translate.c
@@ -6409,11 +6409,7 @@ static void s390x_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cs)
 {
     DisasContext *dc = container_of(dcbase, DisasContext, base);
 
-    /* 31-bit mode */
-    if (!(dc->base.tb->flags & FLAG_MASK_64)) {
-        dc->base.pc_first &= 0x7fffffff;
-        dc->base.pc_next = dc->base.pc_first;
-    }
+    /* Note cpu_get_tb_cpu_state asserts PC is masked for the mode. */
 
     dc->cc_op = CC_OP_DYNAMIC;
     dc->ex_value = dc->base.tb->cs_base;
-- 
2.34.1