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

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

[Nina Schoetterl-Glausch]

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

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

[Nico Boehr]

Quoting Nina Schoetterl-Glausch (2023-02-22 12:47:42)
> 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>
[...]
> 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

You didn't add your new test to unittests.cfg, is this intentional?

Otherwise:

Reviewed-by: Nico Boehr <nrb@linux.ibm.com>

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

[Nina Schoetterl-Glausch]

On Thu, 2023-02-23 at 08:52 +0100, Nico Boehr wrote:
> Quoting Nina Schoetterl-Glausch (2023-02-22 12:47:42)
> > 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>
> [...]
> > 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
> 
> You didn't add your new test to unittests.cfg, is this intentional?

Nope, I just forgot.

@Thomas, I guess I should also add it to s390x-kvm in .gitlab-ci.yml,
since the test passes on KVM?

> 
> Otherwise:
> 
> Reviewed-by: Nico Boehr <nrb@linux.ibm.com>

Thanks!

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

[Thomas Huth]

On 23/02/2023 10.50, Nina Schoetterl-Glausch wrote:
> On Thu, 2023-02-23 at 08:52 +0100, Nico Boehr wrote:
>> Quoting Nina Schoetterl-Glausch (2023-02-22 12:47:42)
>>> 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>
>> [...]
>>> 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
>>
>> You didn't add your new test to unittests.cfg, is this intentional?
> 
> Nope, I just forgot.
> 
> @Thomas, I guess I should also add it to s390x-kvm in .gitlab-ci.yml,
> since the test passes on KVM?

Yes, please (unless your test requires the latest and greatest shiny 
upstream kernel - we don't have that on the machine available yet).

  Thomas