[Qemu-devel] [PATCH for-next 2/5] target-alpha: Use goto_tb in call_pal

[Richard Henderson <rth@twiddle.net>]

With appropriate flushing when the PALBR changes, the target of
a CALL_PAL is so predictable we can chain to it.

Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 target-alpha/helper.h     |  1 +
 target-alpha/sys_helper.c |  5 +++++
 target-alpha/translate.c  | 20 ++++++++++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/target-alpha/helper.h b/target-alpha/helper.h
index 5529c17..732b701 100644
--- a/target-alpha/helper.h
+++ b/target-alpha/helper.h
@@ -112,6 +112,7 @@ DEF_HELPER_3(stq_c_phys, i64, env, i64, i64)
 
 DEF_HELPER_FLAGS_1(tbia, TCG_CALL_NO_RWG, void, env)
 DEF_HELPER_FLAGS_2(tbis, TCG_CALL_NO_RWG, void, env, i64)
+DEF_HELPER_FLAGS_1(tb_flush, TCG_CALL_NO_RWG, void, env)
 
 DEF_HELPER_1(halt, void, i64);
 
diff --git a/target-alpha/sys_helper.c b/target-alpha/sys_helper.c
index ce51ed6..97cf9eb 100644
--- a/target-alpha/sys_helper.c
+++ b/target-alpha/sys_helper.c
@@ -72,6 +72,11 @@ void helper_tbis(CPUAlphaState *env, uint64_t p)
     tlb_flush_page(env, p);
 }
 
+void helper_tb_flush(CPUAlphaState *env)
+{
+    tb_flush(env);
+}
+
 void helper_halt(uint64_t restart)
 {
     if (restart) {
diff --git a/target-alpha/translate.c b/target-alpha/translate.c
index 59389a2..f172670 100644
--- a/target-alpha/translate.c
+++ b/target-alpha/translate.c
@@ -1609,6 +1609,17 @@ static ExitStatus gen_call_pal(DisasContext *ctx, int palcode)
 
         tcg_temp_free(entry);
         tcg_temp_free(pc);
+
+        /* Since the destination is running in PALmode, we don't really
+           need the page permissions check.  We'll see the existance of
+           the page when we create the TB, and we'll flush all TBs if
+           we change the PAL base register.  */
+        if (!ctx->singlestep_enabled && !(ctx->tb->cflags & CF_LAST_IO)) {
+            tcg_gen_goto_tb(0);
+            tcg_gen_exit_tb((tcg_target_long)ctx->tb);
+            return EXIT_GOTO_TB;
+        }
+
         return EXIT_PC_UPDATED;
     }
 #endif
@@ -1727,6 +1738,15 @@ static ExitStatus gen_mtpr(DisasContext *ctx, int rb, int regno)
         gen_helper_set_alarm(cpu_env, tmp);
         break;
 
+    case 7:
+        /* PALBR */
+        tcg_gen_st_i64(tmp, cpu_env, offsetof(CPUAlphaState, palbr));
+        /* Changing the PAL base register implies un-chaining all of the TBs
+           that ended with a CALL_PAL.  Since the base register usually only
+           changes during boot, flushing everything works well.  */
+        gen_helper_tb_flush(cpu_env);
+        return EXIT_PC_STALE;
+
     default:
         /* The basic registers are data only, and unknown registers
            are read-zero, write-ignore.  */
-- 
1.8.3.1