[kvm-unit-tests PATCH v4 2/3] s390x/spec_ex: Add test introducing odd address into PSW

[Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx>]

Instructions on s390 must be halfword aligned.
Introducing an odd instruction address into the PSW leads to a
specification exception when attempting to execute the instruction at
the odd address.
Add a test for this.

Acked-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
Signed-off-by: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx>
---
 s390x/spec_ex.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/s390x/spec_ex.c b/s390x/spec_ex.c
index 2adc5996..ab023347 100644
--- a/s390x/spec_ex.c
+++ b/s390x/spec_ex.c
@@ -88,12 +88,23 @@ static void expect_invalid_psw(struct psw psw)
 	invalid_psw_expected = true;
 }
 
+static void clear_invalid_psw(void)
+{
+	expected_psw = PSW(0, 0);
+	invalid_psw_expected = false;
+}
+
 static int check_invalid_psw(void)
 {
 	/* Since the fixup sets this to false we check for false here. */
 	if (!invalid_psw_expected) {
+		/*
+		 * Early exception recognition: pgm_int_id == 0.
+		 * Late exception recognition: psw address has been
+		 *	incremented by pgm_int_id (unpredictable value)
+		 */
 		if (expected_psw.mask == invalid_psw.mask &&
-		    expected_psw.addr == invalid_psw.addr)
+		    expected_psw.addr == invalid_psw.addr - lowcore.pgm_int_id)
 			return 0;
 		report_fail("Wrong invalid PSW");
 	} else {
@@ -112,6 +123,42 @@ static int psw_bit_12_is_1(void)
 	return check_invalid_psw();
 }
 
+extern char misaligned_code[];
+asm (  ".balign	2\n"
+"	. = . + 1\n"
+"misaligned_code:\n"
+"	larl	%r0,0\n"
+"	br	%r1\n"
+);
+
+static int psw_odd_address(void)
+{
+	struct psw odd = PSW_WITH_CUR_MASK((uint64_t)&misaligned_code);
+	uint64_t executed_addr;
+
+	expect_invalid_psw(odd);
+	fixup_psw.mask = extract_psw_mask();
+	asm volatile ( "xgr	%%r0,%%r0\n"
+		"	larl	%%r1,0f\n"
+		"	stg	%%r1,%[fixup_addr]\n"
+		"	lpswe	%[odd_psw]\n"
+		"0:	lr	%[executed_addr],%%r0\n"
+	: [fixup_addr] "=&T" (fixup_psw.addr),
+	  [executed_addr] "=d" (executed_addr)
+	: [odd_psw] "Q" (odd)
+	: "cc", "%r0", "%r1"
+	);
+
+	if (!executed_addr) {
+		return check_invalid_psw();
+	} else {
+		assert(executed_addr == odd.addr);
+		clear_invalid_psw();
+		report_fail("did not execute unaligned instructions");
+		return 1;
+	}
+}
+
 /* A short PSW needs to have bit 12 set to be valid. */
 static int short_psw_bit_12_is_0(void)
 {
@@ -170,6 +217,7 @@ struct spec_ex_trigger {
 static const struct spec_ex_trigger spec_ex_triggers[] = {
 	{ "psw_bit_12_is_1", &psw_bit_12_is_1, false, &fixup_invalid_psw },
 	{ "short_psw_bit_12_is_0", &short_psw_bit_12_is_0, false, &fixup_invalid_psw },
+	{ "psw_odd_address", &psw_odd_address, false, &fixup_invalid_psw },
 	{ "bad_alignment", &bad_alignment, true, NULL },
 	{ "not_even", &not_even, true, NULL },
 	{ NULL, NULL, false, NULL },
-- 
2.39.1