[kvm-unit-tests PATCH v3 1/2] s390x: Add specification exception test

[Janis Schoetterl-Glausch <scgl@linux.ibm.com>]

Generate specification exceptions and check that they occur.
With the iterations argument one can check if specification
exception interpretation occurs, e.g. by using a high value and
checking that the debugfs counters are substantially lower.
The argument is also useful for estimating the performance benefit
of interpretation.

Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
---
 s390x/Makefile      |   1 +
 s390x/spec_ex.c     | 181 ++++++++++++++++++++++++++++++++++++++++++++
 s390x/unittests.cfg |   3 +
 3 files changed, 185 insertions(+)
 create mode 100644 s390x/spec_ex.c

diff --git a/s390x/Makefile b/s390x/Makefile
index d18b08b..3e42784 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -24,6 +24,7 @@ tests += $(TEST_DIR)/mvpg.elf
 tests += $(TEST_DIR)/uv-host.elf
 tests += $(TEST_DIR)/edat.elf
 tests += $(TEST_DIR)/mvpg-sie.elf
+tests += $(TEST_DIR)/spec_ex.elf
 
 tests_binary = $(patsubst %.elf,%.bin,$(tests))
 ifneq ($(HOST_KEY_DOCUMENT),)
diff --git a/s390x/spec_ex.c b/s390x/spec_ex.c
new file mode 100644
index 0000000..ec3322a
--- /dev/null
+++ b/s390x/spec_ex.c
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright IBM Corp. 2021
+ *
+ * Specification exception test.
+ * Tests that specification exceptions occur when expected.
+ */
+#include <stdlib.h>
+#include <libcflat.h>
+#include <asm/interrupt.h>
+#include <asm/facility.h>
+
+static struct lowcore *lc = (struct lowcore *) 0;
+
+static bool expect_invalid_psw;
+static struct psw expected_psw;
+static struct psw fixup_psw;
+
+/* The standard program exception handler cannot deal with invalid old PSWs,
+ * especially not invalid instruction addresses, as in that case one cannot
+ * find the instruction following the faulting one from the old PSW.
+ * The PSW to return to is set by load_psw.
+ */
+static void fixup_invalid_psw(void)
+{
+	if (expect_invalid_psw) {
+		report(expected_psw.mask == lc->pgm_old_psw.mask
+		       && expected_psw.addr == lc->pgm_old_psw.addr,
+		       "Invalid program new PSW as expected");
+		expect_invalid_psw = false;
+	}
+	lc->pgm_old_psw = fixup_psw;
+}
+
+/* Load possibly invalid psw, but setup fixup_psw before,
+ * so that *fixup_invalid_psw() can bring us back onto the right track.
+ */
+static void load_psw(struct psw psw)
+{
+	uint64_t scratch;
+
+	fixup_psw.mask = extract_psw_mask();
+	asm volatile (
+		"	larl	%[scratch],nop%=\n"
+		"	stg	%[scratch],%[addr]\n"
+		"	lpswe	%[psw]\n"
+		"nop%=:	nop\n"
+		: [scratch] "=&r"(scratch),
+		  [addr] "=&T"(fixup_psw.addr)
+		: [psw] "Q"(psw)
+		: "cc", "memory"
+	);
+}
+
+static void psw_bit_12_is_1(void)
+{
+	expected_psw.mask = 0x0008000000000000;
+	expected_psw.addr = 0x00000000deadbeee;
+	expect_invalid_psw = true;
+	load_psw(expected_psw);
+}
+
+static void bad_alignment(void)
+{
+	uint32_t words[5] = {0, 0, 0};
+	uint32_t (*bad_aligned)[4];
+
+	register uint64_t r1 asm("6");
+	register uint64_t r2 asm("7");
+	if (((uintptr_t)&words[0]) & 0xf)
+		bad_aligned = (uint32_t (*)[4])&words[0];
+	else
+		bad_aligned = (uint32_t (*)[4])&words[1];
+	asm volatile ("lpq %0,%2"
+		      : "=r"(r1), "=r"(r2)
+		      : "T"(*bad_aligned)
+	);
+}
+
+static void not_even(void)
+{
+	uint64_t quad[2];
+
+	register uint64_t r1 asm("7");
+	register uint64_t r2 asm("8");
+	asm volatile (".insn	rxy,0xe3000000008f,%0,%2" //lpq %0,%2
+		      : "=r"(r1), "=r"(r2)
+		      : "T"(quad)
+	);
+}
+
+struct spec_ex_trigger {
+	const char *name;
+	void (*func)(void);
+	void (*fixup)(void);
+};
+
+static const struct spec_ex_trigger spec_ex_triggers[] = {
+	{ "psw_bit_12_is_1", &psw_bit_12_is_1, &fixup_invalid_psw},
+	{ "bad_alignment", &bad_alignment, NULL},
+	{ "not_even", &not_even, NULL},
+	{ NULL, NULL, NULL},
+};
+
+struct args {
+	uint64_t iterations;
+};
+
+static void test_spec_ex(struct args *args,
+			 const struct spec_ex_trigger *trigger)
+{
+	uint16_t expected_pgm = PGM_INT_CODE_SPECIFICATION;
+	uint16_t pgm;
+	unsigned int i;
+
+	for (i = 0; i < args->iterations; i++) {
+		expect_pgm_int();
+		register_pgm_cleanup_func(trigger->fixup);
+		trigger->func();
+		register_pgm_cleanup_func(NULL);
+		pgm = clear_pgm_int();
+		if (pgm != expected_pgm) {
+			report_fail("Program interrupt: expected(%d) == received(%d)",
+				    expected_pgm,
+				    pgm);
+			return;
+		}
+	}
+	report_pass("Program interrupt: always expected(%d) == received(%d)",
+		    expected_pgm,
+		    expected_pgm);
+}
+
+static struct args parse_args(int argc, char **argv)
+{
+	struct args args = {
+		.iterations = 1,
+	};
+	unsigned int i;
+	long arg;
+	bool no_arg;
+	char *end;
+
+	for (i = 1; i < argc; i++) {
+		no_arg = true;
+		if (i < argc - 1) {
+			no_arg = *argv[i + 1] == '\0';
+			arg = strtol(argv[i + 1], &end, 10);
+			no_arg |= *end != '\0';
+			no_arg |= arg < 0;
+		}
+
+		if (!strcmp("--iterations", argv[i])) {
+			if (no_arg)
+				report_abort("--iterations needs a positive parameter");
+			args.iterations = arg;
+			++i;
+		} else {
+			report_abort("Unsupported parameter '%s'",
+				     argv[i]);
+		}
+	}
+	return args;
+}
+
+int main(int argc, char **argv)
+{
+	unsigned int i;
+
+	struct args args = parse_args(argc, argv);
+
+	report_prefix_push("specification exception");
+	for (i = 0; spec_ex_triggers[i].name; i++) {
+		report_prefix_push(spec_ex_triggers[i].name);
+		test_spec_ex(&args, &spec_ex_triggers[i]);
+		report_prefix_pop();
+	}
+	report_prefix_pop();
+
+	return report_summary();
+}
diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
index 9e1802f..5f43d52 100644
--- a/s390x/unittests.cfg
+++ b/s390x/unittests.cfg
@@ -109,3 +109,6 @@ file = edat.elf
 
 [mvpg-sie]
 file = mvpg-sie.elf
+
+[spec_ex]
+file = spec_ex.elf
-- 
2.31.1