[PULL 17/68] target/nios2: Split out helper for eret instruction

[Richard Henderson]

From: Amir Gonnen <amir.gonnen@neuroblade.ai>

The implementation of eret will become much more complex
with the introduction of shadow registers.

[rth: Split out of a larger patch for shadow register sets.
      Directly exit to the cpu loop from the helper.]

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Amir Gonnen <amir.gonnen@neuroblade.ai>
Message-Id: <20220303153906.2024748-3-amir.gonnen@neuroblade.ai>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220421151735.31996-18-richard.henderson@linaro.org>
---
 target/nios2/helper.h    |  1 +
 target/nios2/op_helper.c |  9 +++++++++
 target/nios2/translate.c | 10 ++++++----
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/target/nios2/helper.h b/target/nios2/helper.h
index a44ecfdf7a..525b6b685b 100644
--- a/target/nios2/helper.h
+++ b/target/nios2/helper.h
@@ -21,6 +21,7 @@
 DEF_HELPER_FLAGS_2(raise_exception, TCG_CALL_NO_WG, noreturn, env, i32)
 
 #if !defined(CONFIG_USER_ONLY)
+DEF_HELPER_3(eret, noreturn, env, i32, i32)
 DEF_HELPER_2(mmu_write_tlbacc, void, env, i32)
 DEF_HELPER_2(mmu_write_tlbmisc, void, env, i32)
 DEF_HELPER_2(mmu_write_pteaddr, void, env, i32)
diff --git a/target/nios2/op_helper.c b/target/nios2/op_helper.c
index caa885f7b4..ee5ad8b23f 100644
--- a/target/nios2/op_helper.c
+++ b/target/nios2/op_helper.c
@@ -30,3 +30,12 @@ void helper_raise_exception(CPUNios2State *env, uint32_t 
index)
     cs->exception_index = index;
     cpu_loop_exit(cs);
 }
+
+#ifndef CONFIG_USER_ONLY
+void helper_eret(CPUNios2State *env, uint32_t new_status, uint32_t new_pc)
+{
+    env->regs[CR_STATUS] = new_status;
+    env->pc = new_pc;
+    cpu_loop_exit(env_cpu(env));
+}
+#endif /* !CONFIG_USER_ONLY */
diff --git a/target/nios2/translate.c b/target/nios2/translate.c
index 226bd9e30b..53699ee088 100644
--- a/target/nios2/translate.c
+++ b/target/nios2/translate.c
@@ -391,10 +391,12 @@ static void eret(DisasContext *dc, uint32_t code, 
uint32_t flags)
         return;
     }
 
-    tcg_gen_mov_tl(cpu_R[CR_STATUS], cpu_R[CR_ESTATUS]);
-    tcg_gen_mov_tl(cpu_pc, cpu_R[R_EA]);
-
-    dc->base.is_jmp = DISAS_JUMP;
+#ifdef CONFIG_USER_ONLY
+    g_assert_not_reached();
+#else
+    gen_helper_eret(cpu_env, cpu_R[CR_ESTATUS], cpu_R[R_EA]);
+    dc->base.is_jmp = DISAS_NORETURN;
+#endif
 }
 
 /* PC <- ra */
-- 
2.34.1