[PATCH] target/ppc: fix single-step exception regression

[Luis Pires]

Commit 6086c75 (target/ppc: Replace POWERPC_EXCP_BRANCH with
DISAS_NORETURN) broke the generation of exceptions when
CPU_SINGLE_STEP or CPU_BRANCH_STEP were set, due to nip always being
reset to the address of the current instruction.
This fix leaves nip untouched when generating the exception.

Signed-off-by: Luis Pires <luis.pi...@eldorado.org.br>
Reported-by: Matheus Ferst <matheus.fe...@eldorado.org.br>
---
 target/ppc/translate.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index ea200f9637..0dd04696a6 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -4646,8 +4646,7 @@ static void gen_lookup_and_goto_ptr(DisasContext *ctx)
         if (sse & GDBSTUB_SINGLE_STEP) {
             gen_debug_exception(ctx);
         } else if (sse & (CPU_SINGLE_STEP | CPU_BRANCH_STEP)) {
-            uint32_t excp = gen_prep_dbgex(ctx);
-            gen_exception(ctx, excp);
+            gen_helper_raise_exception(cpu_env, 
tcg_constant_i32(gen_prep_dbgex(ctx)));
         } else {
             tcg_gen_exit_tb(NULL, 0);
         }
@@ -9128,7 +9127,11 @@ static void ppc_tr_tb_stop(DisasContextBase *dcbase, 
CPUState *cs)
         }
         /* else CPU_SINGLE_STEP... */
         if (nip <= 0x100 || nip > 0xf00) {
-            gen_exception(ctx, gen_prep_dbgex(ctx));
+            if (is_jmp == DISAS_EXIT || is_jmp == DISAS_CHAIN) {
+                /* We have not updated nip yet, so do it now */
+                gen_update_nip(ctx, nip);
+            }
+            gen_helper_raise_exception(cpu_env, 
tcg_constant_i32(gen_prep_dbgex(ctx)));
             return;
         }
     }
-- 
2.25.1