[PATCH v3 18/30] target/ppc: Move single-step check to ppc_tr_tb_stop

[Richard Henderson <richard.henderson@linaro.org>]

When single-stepping, force max_insns to 1 in init_disas
so that we exit the translation loop immediately.

Combine the single-step checks in tb_stop, and give the
gdb exception priority over the cpu exception, just as
we already do in gen_lookup_and_goto_ptr.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/ppc/translate.c | 37 +++++++++++++++++++------------------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index d78071a4a4..c018960ce9 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -7910,7 +7910,6 @@ static void ppc_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cs)
 {
     DisasContext *ctx = container_of(dcbase, DisasContext, base);
     CPUPPCState *env = cs->env_ptr;
-    int bound;
 
     ctx->spr_cb = env->spr_cb;
     ctx->pr = msr_pr;
@@ -7986,13 +7985,13 @@ static void ppc_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cs)
     if (unlikely(ctx->base.singlestep_enabled)) {
         ctx->singlestep_enabled |= GDBSTUB_SINGLE_STEP;
     }
-#if defined(DO_SINGLE_STEP) && 0
-    /* Single step trace mode */
-    msr_se = 1;
-#endif
 
-    bound = -(ctx->base.pc_first | TARGET_PAGE_MASK) / 4;
-    ctx->base.max_insns = MIN(ctx->base.max_insns, bound);
+    if (ctx->singlestep_enabled & (CPU_SINGLE_STEP | GDBSTUB_SINGLE_STEP)) {
+        ctx->base.max_insns = 1;
+    } else {
+        int bound = -(ctx->base.pc_first | TARGET_PAGE_MASK) / 4;
+        ctx->base.max_insns = MIN(ctx->base.max_insns, bound);
+    }
 }
 
 static void ppc_tr_tb_start(DisasContextBase *db, CPUState *cs)
@@ -8046,14 +8045,6 @@ static void ppc_tr_translate_insn(DisasContextBase *dcbase, CPUState *cs)
     handler->count++;
 #endif
 
-    /* Check trace mode exceptions */
-    if (unlikely(ctx->singlestep_enabled & CPU_SINGLE_STEP &&
-                 (ctx->base.pc_next <= 0x100 || ctx->base.pc_next > 0xF00) &&
-                 ctx->base.is_jmp != DISAS_NORETURN)) {
-        uint32_t excp = gen_prep_dbgex(ctx);
-        gen_exception_nip(ctx, excp, ctx->base.pc_next);
-    }
-
     if (tcg_check_temp_count()) {
         qemu_log("Opcode %02x %02x %02x %02x (%08x) leaked "
                  "temporaries\n", opc1(ctx->opcode), opc2(ctx->opcode),
@@ -8066,6 +8057,7 @@ static void ppc_tr_tb_stop(DisasContextBase *dcbase, CPUState *cs)
     DisasContext *ctx = container_of(dcbase, DisasContext, base);
     DisasJumpType is_jmp = ctx->base.is_jmp;
     target_ulong nip = ctx->base.pc_next;
+    int sse;
 
     if (is_jmp == DISAS_NORETURN) {
         /* We have already exited the TB. */
@@ -8073,7 +8065,8 @@ static void ppc_tr_tb_stop(DisasContextBase *dcbase, CPUState *cs)
     }
 
     /* Honor single stepping. */
-    if (unlikely(ctx->base.singlestep_enabled)) {
+    sse = ctx->singlestep_enabled & (CPU_SINGLE_STEP | GDBSTUB_SINGLE_STEP);
+    if (unlikely(sse)) {
         switch (is_jmp) {
         case DISAS_TOO_MANY:
         case DISAS_EXIT_UPDATE:
@@ -8086,8 +8079,16 @@ static void ppc_tr_tb_stop(DisasContextBase *dcbase, CPUState *cs)
         default:
             g_assert_not_reached();
         }
-        gen_debug_exception(ctx);
-        return;
+
+        if (sse & GDBSTUB_SINGLE_STEP) {
+            gen_debug_exception(ctx);
+            return;
+        }
+        /* else CPU_SINGLE_STEP... */
+        if (nip <= 0x100 || nip > 0xf00) {
+            gen_exception(ctx, gen_prep_dbgex(ctx));
+            return;
+        }
     }
 
     switch (is_jmp) {
-- 
2.25.1