tests/tcg/s390x: Add bal.S

Add a small test to prevent regressions.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221103130011.2670186-1-iii@linux.ibm.com>
Message-Id: <20230220184052.163465-6-richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/tcg/s390x/Makefile.softmmu-target

@@ -7,3 +7,4 @@ QEMU_OPTS=-action panic=exit-failure -kernel
 		-Wl,--build-id=none $< -o $@
 
 TESTS += unaligned-lowcore
+TESTS += bal

tests/tcg/s390x/bal.S

@@ -0,0 +1,24 @@
+    .org 0x200                         /* lowcore padding */
+    .globl _start
+_start:
+    lpswe start24_psw
+_start24:
+    lgrl %r0,initial_r0
+    lgrl %r1,expected_r0
+    bal %r0,0f
+0:
+    cgrjne %r0,%r1,1f
+    lpswe success_psw
+1:
+    lpswe failure_psw
+    .align 8
+start24_psw:
+    .quad 0x160000000000,_start24      /* 24-bit mode, cc = 1, pm = 6 */
+initial_r0:
+    .quad 0x1234567887654321
+expected_r0:
+    .quad 0x1234567896000000 + 0b      /* ilc = 2, cc = 1, pm = 6 */
+success_psw:
+    .quad 0x2000000000000,0xfff        /* see is_special_wait_psw() */
+failure_psw:
+    .quad 0x2000000000000,0            /* disabled wait */