[kvm-unit-tests PATCH v1] s390x: Add tests for execute-type instructions

[Nina Schoetterl-Glausch <nsg@linux.ibm.com>]

Test the instruction address used by targets of an execute instruction.
When the target instruction calculates a relative address, the result is
relative to the target instruction, not the execute instruction.

Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
---


TCG does the address calculation relative to the execute instruction.


 s390x/Makefile |  1 +
 s390x/ex.c     | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 93 insertions(+)
 create mode 100644 s390x/ex.c

diff --git a/s390x/Makefile b/s390x/Makefile
index 97a61611..6cf8018b 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -39,6 +39,7 @@ tests += $(TEST_DIR)/panic-loop-extint.elf
 tests += $(TEST_DIR)/panic-loop-pgm.elf
 tests += $(TEST_DIR)/migration-sck.elf
 tests += $(TEST_DIR)/exittime.elf
+tests += $(TEST_DIR)/ex.elf
 
 pv-tests += $(TEST_DIR)/pv-diags.elf
 
diff --git a/s390x/ex.c b/s390x/ex.c
new file mode 100644
index 00000000..1bf4d8cd
--- /dev/null
+++ b/s390x/ex.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright IBM Corp. 2023
+ *
+ * Test EXECUTE (RELATIVE LONG).
+ */
+
+#include <libcflat.h>
+
+static void test_basr(void)
+{
+	uint64_t ret_addr, after_ex;
+
+	report_prefix_push("BASR");
+	asm volatile ( ".pushsection .rodata\n"
+		"0:	basr	%[ret_addr],0\n"
+		"	.popsection\n"
+
+		"	larl	%[after_ex],1f\n"
+		"	exrl	0,0b\n"
+		"1:\n"
+		: [ret_addr] "=d" (ret_addr),
+		  [after_ex] "=d" (after_ex)
+	);
+
+	report(ret_addr == after_ex, "return address after EX");
+	report_prefix_pop();
+}
+
+/*
+ * According to PoP (Branch-Address Generation), the address is relative to
+ * BRAS when it is the target of an execute-type instruction.
+ */
+static void test_bras(void)
+{
+	uint64_t after_target, ret_addr, after_ex, branch_addr;
+
+	report_prefix_push("BRAS");
+	asm volatile ( ".pushsection .text.ex_bras, \"x\"\n"
+		"0:	bras	%[ret_addr],1f\n"
+		"	nopr	%%r7\n"
+		"1:	larl	%[branch_addr],0\n"
+		"	j	4f\n"
+		"	.popsection\n"
+
+		"	larl	%[after_target],1b\n"
+		"	larl	%[after_ex],3f\n"
+		"2:	exrl	0,0b\n"
+		"3:	larl	%[branch_addr],0\n"
+		"4:\n"
+
+		"	.if (1b - 0b) != (3b - 2b)\n"
+		"	.error	\"right and wrong target must have same offset\"\n"
+		"	.endif\n"
+		: [after_target] "=d" (after_target),
+		  [ret_addr] "=d" (ret_addr),
+		  [after_ex] "=d" (after_ex),
+		  [branch_addr] "=d" (branch_addr)
+	);
+
+	report(after_target == branch_addr, "address calculated relative to BRAS");
+	report(ret_addr == after_ex, "return address after EX");
+	report_prefix_pop();
+}
+
+static void test_larl(void)
+{
+	uint64_t target, addr;
+
+	report_prefix_push("LARL");
+	asm volatile ( ".pushsection .rodata\n"
+		"0:	larl	%[addr],0\n"
+		"	.popsection\n"
+
+		"	larl	%[target],0b\n"
+		"	exrl	0,0b\n"
+		: [target] "=d" (target),
+		  [addr] "=d" (addr)
+	);
+
+	report(target == addr, "address calculated relative to LARL");
+	report_prefix_pop();
+}
+
+int main(int argc, char **argv)
+{
+	test_basr();
+	test_bras();
+	test_larl();
+
+	return report_summary();
+}

base-commit: e3c5c3ef2524c58023073c0fadde2e8ae3c04ec6
-- 
2.36.1