target/s390x: Fix CLC corrupting cc_src

CLC updates cc_src before accessing the second operand; if the latter
is inaccessible, the former ends up containing a bogus value.

Fix by reading cc_src into a temporary first.

Fixes: 4f7403d52b1c ("target-s390: Convert CLC")
Closes: https://gitlab.com/qemu-project/qemu/-/issues/1865
Cc: qemu-stable@nongnu.org
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-ID: <20231106093605.1349201-2-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

diff --git a/target/s390x/tcg/translate.c b/target/s390x/tcg/translate.c
index 4bae1509f5078d6e1a052160ae034e0b3c22d8e0..a0d6a2a35dd3addccea52875e39887ae91e3dda6 100644 (file)
--- a/target/s390x/tcg/translate.c
+++ b/target/s390x/tcg/translate.c
@@ -2007,6 +2007,7 @@ static DisasJumpType op_cksm(DisasContext *s, DisasOps *o)
 static DisasJumpType op_clc(DisasContext *s, DisasOps *o)
 {
     int l = get_field(s, l1);
+    TCGv_i64 src;
     TCGv_i32 vl;
     MemOp mop;
 
@@ -2016,9 +2017,11 @@ static DisasJumpType op_clc(DisasContext *s, DisasOps *o)
     case 4:
     case 8:
         mop = ctz32(l + 1) | MO_TE;
-        tcg_gen_qemu_ld_tl(cc_src, o->addr1, get_mem_index(s), mop);
+        /* Do not update cc_src yet: loading cc_dst may cause an exception. */
+        src = tcg_temp_new_i64();
+        tcg_gen_qemu_ld_tl(src, o->addr1, get_mem_index(s), mop);
         tcg_gen_qemu_ld_tl(cc_dst, o->in2, get_mem_index(s), mop);
-        gen_op_update2_cc_i64(s, CC_OP_LTUGTU_64, cc_src, cc_dst);
+        gen_op_update2_cc_i64(s, CC_OP_LTUGTU_64, src, cc_dst);
         return DISAS_NEXT;
     default:
         vl = tcg_constant_i32(l);