[PATCH 1/2] target/s390x: Fix EXECUTE of relative branches

[Ilya Leoshkevich <iii@linux.ibm.com>]

Fix a problem similar to the one fixed by commit 703d03a4aaf3
("target/s390x: Fix EXECUTE of relative long instructions"), but now
for relative branches.

Reported-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 target/s390x/tcg/translate.c | 81 ++++++++++++++++++++++++++----------
 1 file changed, 58 insertions(+), 23 deletions(-)

diff --git a/target/s390x/tcg/translate.c b/target/s390x/tcg/translate.c
index 46b874e94da..2a681428af1 100644
--- a/target/s390x/tcg/translate.c
+++ b/target/s390x/tcg/translate.c
@@ -1534,18 +1534,51 @@ static DisasJumpType op_bal(DisasContext *s, DisasOps *o)
     }
 }
 
+/*
+ * Disassemble the target of a branch. The results are returned in a form
+ * suitable for passing into help_branch():
+ *
+ * - bool IS_IMM reflects whether the target is fixed or computed. Non-EXECUTEd
+ *   branches, whose DisasContext *S contains the relative immediate field RI,
+ *   are considered fixed. All the other branches are considered computed.
+ * - int IMM is the value of RI.
+ * - TCGv_i64 CDEST is the address of the computed target.
+ */
+#define disas_jdest(s, ri, is_imm, imm, cdest) do {                            \
+    if (have_field(s, ri)) {                                                   \
+        if (unlikely(s->ex_value)) {                                           \
+            cdest = tcg_temp_new_i64();                                        \
+            tcg_gen_ld_i64(cdest, cpu_env, offsetof(CPUS390XState, ex_target));\
+            tcg_gen_addi_i64(cdest, cdest, (int64_t)get_field(s, ri) * 2);     \
+            is_imm = false;                                                    \
+        } else {                                                               \
+            is_imm = true;                                                     \
+        }                                                                      \
+    } else {                                                                   \
+        is_imm = false;                                                        \
+    }                                                                          \
+    imm = is_imm ? get_field(s, ri) : 0;                                       \
+} while (false)
+
 static DisasJumpType op_basi(DisasContext *s, DisasOps *o)
 {
+    DisasCompare c;
+    bool is_imm;
+    int imm;
+
     pc_to_link_info(o->out, s, s->pc_tmp);
-    return help_goto_direct(s, s->base.pc_next + (int64_t)get_field(s, i2) * 2);
+
+    disas_jdest(s, i2, is_imm, imm, o->in2);
+    disas_jcc(s, &c, 0xf);
+    return help_branch(s, &c, is_imm, imm, o->in2);
 }
 
 static DisasJumpType op_bc(DisasContext *s, DisasOps *o)
 {
     int m1 = get_field(s, m1);
-    bool is_imm = have_field(s, i2);
-    int imm = is_imm ? get_field(s, i2) : 0;
     DisasCompare c;
+    bool is_imm;
+    int imm;
 
     /* BCR with R2 = 0 causes no branching */
     if (have_field(s, r2) && get_field(s, r2) == 0) {
@@ -1562,6 +1595,7 @@ static DisasJumpType op_bc(DisasContext *s, DisasOps *o)
         return DISAS_NEXT;
     }
 
+    disas_jdest(s, i2, is_imm, imm, o->in2);
     disas_jcc(s, &c, m1);
     return help_branch(s, &c, is_imm, imm, o->in2);
 }
@@ -1569,10 +1603,10 @@ static DisasJumpType op_bc(DisasContext *s, DisasOps *o)
 static DisasJumpType op_bct32(DisasContext *s, DisasOps *o)
 {
     int r1 = get_field(s, r1);
-    bool is_imm = have_field(s, i2);
-    int imm = is_imm ? get_field(s, i2) : 0;
     DisasCompare c;
+    bool is_imm;
     TCGv_i64 t;
+    int imm;
 
     c.cond = TCG_COND_NE;
     c.is_64 = false;
@@ -1584,6 +1618,7 @@ static DisasJumpType op_bct32(DisasContext *s, DisasOps *o)
     c.u.s32.b = tcg_constant_i32(0);
     tcg_gen_extrl_i64_i32(c.u.s32.a, t);
 
+    disas_jdest(s, i2, is_imm, imm, o->in2);
     return help_branch(s, &c, is_imm, imm, o->in2);
 }
 
@@ -1611,9 +1646,9 @@ static DisasJumpType op_bcth(DisasContext *s, DisasOps *o)
 static DisasJumpType op_bct64(DisasContext *s, DisasOps *o)
 {
     int r1 = get_field(s, r1);
-    bool is_imm = have_field(s, i2);
-    int imm = is_imm ? get_field(s, i2) : 0;
     DisasCompare c;
+    bool is_imm;
+    int imm;
 
     c.cond = TCG_COND_NE;
     c.is_64 = true;
@@ -1622,6 +1657,7 @@ static DisasJumpType op_bct64(DisasContext *s, DisasOps *o)
     c.u.s64.a = regs[r1];
     c.u.s64.b = tcg_constant_i64(0);
 
+    disas_jdest(s, i2, is_imm, imm, o->in2);
     return help_branch(s, &c, is_imm, imm, o->in2);
 }
 
@@ -1629,10 +1665,10 @@ static DisasJumpType op_bx32(DisasContext *s, DisasOps *o)
 {
     int r1 = get_field(s, r1);
     int r3 = get_field(s, r3);
-    bool is_imm = have_field(s, i2);
-    int imm = is_imm ? get_field(s, i2) : 0;
     DisasCompare c;
+    bool is_imm;
     TCGv_i64 t;
+    int imm;
 
     c.cond = (s->insn->data ? TCG_COND_LE : TCG_COND_GT);
     c.is_64 = false;
@@ -1645,6 +1681,7 @@ static DisasJumpType op_bx32(DisasContext *s, DisasOps *o)
     tcg_gen_extrl_i64_i32(c.u.s32.b, regs[r3 | 1]);
     store_reg32_i64(r1, t);
 
+    disas_jdest(s, i2, is_imm, imm, o->in2);
     return help_branch(s, &c, is_imm, imm, o->in2);
 }
 
@@ -1652,9 +1689,9 @@ static DisasJumpType op_bx64(DisasContext *s, DisasOps *o)
 {
     int r1 = get_field(s, r1);
     int r3 = get_field(s, r3);
-    bool is_imm = have_field(s, i2);
-    int imm = is_imm ? get_field(s, i2) : 0;
     DisasCompare c;
+    bool is_imm;
+    int imm;
 
     c.cond = (s->insn->data ? TCG_COND_LE : TCG_COND_GT);
     c.is_64 = true;
@@ -1668,6 +1705,7 @@ static DisasJumpType op_bx64(DisasContext *s, DisasOps *o)
     tcg_gen_add_i64(regs[r1], regs[r1], regs[r3]);
     c.u.s64.a = regs[r1];
 
+    disas_jdest(s, i2, is_imm, imm, o->in2);
     return help_branch(s, &c, is_imm, imm, o->in2);
 }
 
@@ -1685,10 +1723,9 @@ static DisasJumpType op_cj(DisasContext *s, DisasOps *o)
     c.u.s64.a = o->in1;
     c.u.s64.b = o->in2;
 
-    is_imm = have_field(s, i4);
-    if (is_imm) {
-        imm = get_field(s, i4);
-    } else {
+    o->out = NULL;
+    disas_jdest(s, i4, is_imm, imm, o->out);
+    if (!is_imm && !o->out) {
         imm = 0;
         o->out = get_address(s, 0, get_field(s, b4),
                              get_field(s, d4));
@@ -5774,15 +5811,13 @@ static void in2_a2(DisasContext *s, DisasOps *o)
 
 static TCGv gen_ri2(DisasContext *s)
 {
-    int64_t delta = (int64_t)get_field(s, i2) * 2;
-    TCGv ri2;
+    TCGv ri2 = NULL;
+    bool is_imm;
+    int imm;
 
-    if (unlikely(s->ex_value)) {
-        ri2 = tcg_temp_new_i64();
-        tcg_gen_ld_i64(ri2, cpu_env, offsetof(CPUS390XState, ex_target));
-        tcg_gen_addi_i64(ri2, ri2, delta);
-    } else {
-        ri2 = tcg_constant_i64(s->base.pc_next + delta);
+    disas_jdest(s, i2, is_imm, imm, ri2);
+    if (is_imm) {
+        ri2 = tcg_constant_i64(s->base.pc_next + imm * 2);
     }
 
     return ri2;
-- 
2.40.0