tests/tcg/s390x: Test single-stepping SVC

Add a small test to prevent regressions.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230510230213.330134-3-iii@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit be4a4cb429617a8b6893733b37b6203e4b7bf35b)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

tests/tcg/s390x/Makefile.target

@@ -56,7 +56,16 @@ run-gdbstub-signals-s390x: signals-s390x
 		--bin $< --test $(S390X_SRC)/gdbstub/test-signals-s390x.py, \
 	mixing signals and debugging)
 
-EXTRA_RUNS += run-gdbstub-signals-s390x
+hello-s390x-asm: CFLAGS+=-nostdlib
+
+run-gdbstub-svc: hello-s390x-asm
+	$(call run-test, $@, $(GDB_SCRIPT) \
+		--gdb $(HAVE_GDB_BIN) \
+		--qemu $(QEMU) --qargs "$(QEMU_OPTS)" \
+		--bin $< --test $(S390X_SRC)/gdbstub/test-svc.py, \
+	single-stepping svc)
+
+EXTRA_RUNS += run-gdbstub-signals-s390x run-gdbstub-svc
 endif
 
 # MVX versions of sha512

tests/tcg/s390x/gdbstub/test-svc.py

@@ -0,0 +1,64 @@
+"""Test single-stepping SVC.
+
+This runs as a sourced script (via -x, via run-test.py)."""
+from __future__ import print_function
+import gdb
+import sys
+
+
+n_failures = 0
+
+
+def report(cond, msg):
+    """Report success/fail of a test"""
+    if cond:
+        print("PASS: {}".format(msg))
+    else:
+        print("FAIL: {}".format(msg))
+        global n_failures
+        n_failures += 1
+
+
+def run_test():
+    """Run through the tests one by one"""
+    report("lghi\t" in gdb.execute("x/i $pc", False, True), "insn #1")
+    gdb.execute("si")
+    report("larl\t" in gdb.execute("x/i $pc", False, True), "insn #2")
+    gdb.execute("si")
+    report("lghi\t" in gdb.execute("x/i $pc", False, True), "insn #3")
+    gdb.execute("si")
+    report("svc\t" in gdb.execute("x/i $pc", False, True), "insn #4")
+    gdb.execute("si")
+    report("xgr\t" in gdb.execute("x/i $pc", False, True), "insn #5")
+    gdb.execute("si")
+    report("svc\t" in gdb.execute("x/i $pc", False, True), "insn #6")
+    gdb.execute("si")
+
+
+def main():
+    """Prepare the environment and run through the tests"""
+    try:
+        inferior = gdb.selected_inferior()
+        print("ATTACHED: {}".format(inferior.architecture().name()))
+    except (gdb.error, AttributeError):
+        print("SKIPPING (not connected)")
+        exit(0)
+
+    if gdb.parse_and_eval('$pc') == 0:
+        print("SKIP: PC not set")
+        exit(0)
+
+    try:
+        # These are not very useful in scripts
+        gdb.execute("set pagination off")
+        gdb.execute("set confirm off")
+
+        # Run the actual tests
+        run_test()
+    except gdb.error:
+        report(False, "GDB Exception: {}".format(sys.exc_info()[0]))
+    print("All tests complete: %d failures" % n_failures)
+    exit(n_failures)
+
+
+main()

tests/tcg/s390x/hello-s390x-asm.S

@@ -0,0 +1,20 @@
+/*
+ * Hello, World! in assembly.
+ */
+
+.globl _start
+_start:
+
+/* puts("Hello, World!"); */
+lghi %r2,1
+larl %r3,foo
+lghi %r4,foo_end-foo
+svc 4
+
+/* exit(0); */
+xgr %r2,%r2
+svc 1
+
+.align 2
+foo: .asciz "Hello, World!\n"
+foo_end: