[PATCH v5 06/48] target/nios2: Fix BRET instruction

[Richard Henderson]

We had failed to copy BSTATUS back to STATUS, and diagnose
supervisor-only.  The spec is light on the specifics of the
implementation of bret, but it is an easy assumption that
the restore into STATUS should work the same as eret.

Therefore, reuse the existing helper_eret.

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/nios2/translate.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/target/nios2/translate.c b/target/nios2/translate.c
index 7c2c430e99..3f7bbd6d7b 100644
--- a/target/nios2/translate.c
+++ b/target/nios2/translate.c
@@ -407,12 +407,22 @@ static void ret(DisasContext *dc, uint32_t code, uint32_t 
flags)
     dc->base.is_jmp = DISAS_JUMP;
 }
 
-/* PC <- ba */
+/*
+ * status <- bstatus
+ * PC <- ba
+ */
 static void bret(DisasContext *dc, uint32_t code, uint32_t flags)
 {
-    tcg_gen_mov_tl(cpu_pc, cpu_R[R_BA]);
+    if (!gen_check_supervisor(dc)) {
+        return;
+    }
 
-    dc->base.is_jmp = DISAS_JUMP;
+#ifdef CONFIG_USER_ONLY
+    g_assert_not_reached();
+#else
+    gen_helper_eret(cpu_env, cpu_R[CR_BSTATUS], cpu_R[R_BA]);
+    dc->base.is_jmp = DISAS_NORETURN;
+#endif
 }
 
 /* PC <- rA */
-- 
2.25.1