[kvm-unit-tests PATCH v2 1/5] s390x: Add specification exception test

Janis Schoetterl-Glausch
2021-10-05T09:09:38Z

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 | 182 ++++++++++++++++++++++++++++++++++++++++++++
s390x/unittests.cfg | 3 +
3 files changed, 186 insertions(+)
create mode 100644 s390x/spec_ex.c

diff --git a/s390x/Makefile b/s390x/Makefile
index ef8041a..57d7c9e 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..dd0ee53
--- /dev/null
+++ b/s390x/spec_ex.c
@@ -0,0 +1,182 @@
+// 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;
+}
+
+static void load_psw(struct psw psw)
+{
+ uint64_t r0 = 0, r1 = 0;
+
+ asm volatile (
+ " epsw %0,%1\n"
+ " st %0,%[mask]\n"
+ " st %1,4+%[mask]\n"
+ " larl %0,nop%=\n"
+ " stg %0,%[addr]\n"
+ " lpswe %[psw]\n"
+ "nop%=: nop\n"
+ : "+&r"(r0), "+&a"(r1), [mask] "=&R"(fixup_psw.mask),
+ [addr] "=&R"(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(0,
+ "Program interrupt: expected(%d) == received(%d)",
+ expected_pgm,
+ pgm);
+ return;
+ }
+ }
+ report(1,
+ "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