From 179a3aacdf8eb16977ee5596df7f84a7d0828b3a Mon Sep 17 00:00:00 2001
From: Richard Henderson <richard.henderson@linaro.org>
Date: Thu, 25 Feb 2021 14:04:16 -0500
Subject: [PATCH] target/arm: Add DISAS_UPDATE_NOCHAIN

Add an option that writes back the PC, like DISAS_UPDATE_EXIT,
but does not exit back to the main loop.

Backports commit 329833286d7a1b0ef8c7daafe13c6ae32429694e from qemu
---
 qemu/target/arm/translate-a64.c | 3 +++
 qemu/target/arm/translate.c     | 4 ++++
 qemu/target/arm/translate.h     | 2 ++
 3 files changed, 9 insertions(+)

diff --git a/qemu/target/arm/translate-a64.c b/qemu/target/arm/translate-a64.c
index 5bb3e2b4..903809b0 100644
--- a/qemu/target/arm/translate-a64.c
+++ b/qemu/target/arm/translate-a64.c
@@ -14626,6 +14626,9 @@ static void aarch64_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
         case DISAS_EXIT:
             tcg_gen_exit_tb(tcg_ctx, NULL, 0);
             break;
+        case DISAS_UPDATE_NOCHAIN:
+            gen_a64_set_pc_im(dc, dc->base.pc_next);
+            /* fall through */
         case DISAS_JUMP:
             tcg_gen_lookup_and_goto_ptr(tcg_ctx);
             break;
diff --git a/qemu/target/arm/translate.c b/qemu/target/arm/translate.c
index 9e275c44..e0d2e3ec 100644
--- a/qemu/target/arm/translate.c
+++ b/qemu/target/arm/translate.c
@@ -9165,6 +9165,7 @@ static void arm_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
         case DISAS_NEXT:
         case DISAS_TOO_MANY:
         case DISAS_UPDATE_EXIT:
+        case DISAS_UPDATE_NOCHAIN:
             gen_set_pc_im(dc, dc->base.pc_next);
             /* fall through */
         default:
@@ -9188,6 +9189,9 @@ static void arm_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
         case DISAS_TOO_MANY:
             gen_goto_tb(dc, 1, dc->base.pc_next);
             break;
+        case DISAS_UPDATE_NOCHAIN:
+            gen_set_pc_im(dc, dc->base.pc_next);
+            /* fall through */
         case DISAS_JUMP:
             gen_goto_ptr(dc);
             break;
diff --git a/qemu/target/arm/translate.h b/qemu/target/arm/translate.h
index 5783ca7a..e75809b9 100644
--- a/qemu/target/arm/translate.h
+++ b/qemu/target/arm/translate.h
@@ -176,6 +176,8 @@ static inline void disas_set_insn_syndrome(DisasContext *s, uint32_t syn)
  * return from cpu_tb_exec.
  */
 #define DISAS_EXIT      DISAS_TARGET_9
+/* CPU state was modified dynamically; no need to exit, but do not chain. */
+#define DISAS_UPDATE_NOCHAIN  DISAS_TARGET_10
 
 #ifdef TARGET_AARCH64
 void a64_translate_init(struct uc_struct *uc);