target/s390x: Add ilen to unwind data

Use ILEN_UNWIND to signal that we have in fact that cpu_restore_state
will have been called by the time we arrive in do_program_interrupt.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Message-Id: <20191001171614.8405-2-richard.henderson@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>

target/s390x/cpu.h

@@ -34,7 +34,7 @@
 /* The z/Architecture has a strong memory model with some store-after-load re-ordering */
 #define TCG_GUEST_DEFAULT_MO      (TCG_MO_ALL & ~TCG_MO_ST_LD)
 
-#define TARGET_INSN_START_EXTRA_WORDS 1
+#define TARGET_INSN_START_EXTRA_WORDS 2
 
 #define MMU_MODE0_SUFFIX _primary
 #define MMU_MODE1_SUFFIX _secondary
@@ -804,6 +804,8 @@ int cpu_s390x_signal_handler(int host_signum, void *pinfo, void *puc);
 void s390_crw_mchk(void);
 void s390_io_interrupt(uint16_t subchannel_id, uint16_t subchannel_nr,
                        uint32_t io_int_parm, uint32_t io_int_word);
+/* instruction length set by unwind info */
+#define ILEN_UNWIND                 0
 /* automatically detect the instruction length */
 #define ILEN_AUTO                   0xff
 #define RA_IGNORED                  0

target/s390x/interrupt.c

@@ -28,7 +28,10 @@ void trigger_pgm_exception(CPUS390XState *env, uint32_t code, uint32_t ilen)
 
     cs->exception_index = EXCP_PGM;
     env->int_pgm_code = code;
-    env->int_pgm_ilen = ilen;
+    /* If ILEN_UNWIND, int_pgm_ilen already has the correct value.  */
+    if (ilen != ILEN_UNWIND) {
+        env->int_pgm_ilen = ilen;
+    }
 }
 
 void s390_program_interrupt(CPUS390XState *env, uint32_t code, int ilen,

target/s390x/translate.c

@@ -6309,6 +6309,9 @@ static DisasJumpType translate_one(CPUS390XState *env, DisasContext *s)
     /* Search for the insn in the table.  */
     insn = extract_insn(env, s, &f);
 
+    /* Emit insn_start now that we know the ILEN.  */
+    tcg_gen_insn_start(s->base.pc_next, s->cc_op, s->ilen);
+
     /* Not found means unimplemented/illegal opcode.  */
     if (insn == NULL) {
         qemu_log_mask(LOG_UNIMP, "unimplemented opcode 0x%02x%02x\n",
@@ -6463,9 +6466,6 @@ static void s390x_tr_tb_start(DisasContextBase *db, CPUState *cs)
 
 static void s390x_tr_insn_start(DisasContextBase *dcbase, CPUState *cs)
 {
-    DisasContext *dc = container_of(dcbase, DisasContext, base);
-
-    tcg_gen_insn_start(dc->base.pc_next, dc->cc_op);
 }
 
 static bool s390x_tr_breakpoint_check(DisasContextBase *dcbase, CPUState *cs,
@@ -6473,6 +6473,14 @@ static bool s390x_tr_breakpoint_check(DisasContextBase *dcbase, CPUState *cs,
 {
     DisasContext *dc = container_of(dcbase, DisasContext, base);
 
+    /*
+     * Emit an insn_start to accompany the breakpoint exception.
+     * The ILEN value is a dummy, since this does not result in
+     * an s390x exception, but an internal qemu exception which
+     * brings us back to interact with the gdbstub.
+     */
+    tcg_gen_insn_start(dc->base.pc_next, dc->cc_op, 2);
+
     dc->base.is_jmp = DISAS_PC_STALE;
     dc->do_debug = true;
     /* The address covered by the breakpoint must be included in
@@ -6567,8 +6575,14 @@ void restore_state_to_opc(CPUS390XState *env, TranslationBlock *tb,
                           target_ulong *data)
 {
     int cc_op = data[1];
+
     env->psw.addr = data[0];
+
+    /* Update the CC opcode if it is not already up-to-date.  */
     if ((cc_op != CC_OP_DYNAMIC) && (cc_op != CC_OP_STATIC)) {
         env->cc_op = cc_op;
     }
+
+    /* Record ILEN.  */
+    env->int_pgm_ilen = data[2];
 }