[kvm-unit-tests GIT PULL v3 11/14] s390x: Add tests for execute-type instructions

[Nico Boehr <nrb@linux.ibm.com>]

From: 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.

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Link: https://lore.kernel.org/r/20230317112339.774659-1-nsg@linux.ibm.com
[ nrb: add ifndef __clang__ guard around if in assembly ]
Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
---
 s390x/Makefile      |   1 +
 s390x/ex.c          | 197 ++++++++++++++++++++++++++++++++++++++++++++
 s390x/unittests.cfg |   3 +
 .gitlab-ci.yml      |   1 +
 4 files changed, 202 insertions(+)
 create mode 100644 s390x/ex.c

diff --git a/s390x/Makefile b/s390x/Makefile
index ab146eb..a80db53 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 0000000..92b387c
--- /dev/null
+++ b/s390x/ex.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright IBM Corp. 2023
+ *
+ * Test EXECUTE (RELATIVE LONG).
+ * These instructions execute a target instruction. The target instruction is formed
+ * by reading an instruction from memory and optionally modifying some of its bits.
+ * The execution of the target instruction is the same as if it was executed
+ * normally as part of the instruction sequence, except for the instruction
+ * address and the instruction-length code.
+ */
+
+#include <libcflat.h>
+
+/*
+ * Accesses to the operand of execute-type instructions are instruction fetches.
+ * Minimum alignment is two, since the relative offset is specified by number of halfwords.
+ */
+asm (  ".pushsection .text.exrl_targets,\"x\"\n"
+"	.balign	2\n"
+"	.popsection\n"
+);
+
+/*
+ * BRANCH AND SAVE, register register variant.
+ * Saves the next instruction address (address from PSW + length of instruction)
+ * to the first register. No branch is taken in this test, because 0 is
+ * specified as target.
+ * BASR does *not* perform a relative address calculation with an intermediate.
+ */
+static void test_basr(void)
+{
+	uint64_t ret_addr, after_ex;
+
+	report_prefix_push("BASR");
+	asm volatile ( ".pushsection .text.exrl_targets\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();
+}
+
+/*
+ * BRANCH RELATIVE AND SAVE.
+ * According to PoP (Branch-Address Generation), the address calculated relative
+ * to the instruction address is relative to BRAS when it is the target of an
+ * execute-type instruction, not relative to the 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.exrl_targets\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"
+/*
+ * In case the address calculation is correct, we jump by the relative offset 1b-0b from 0b to 1b.
+ * In case the address calculation is relative to the exrl (i.e. a test failure),
+ * put a valid instruction at the same relative offset from the exrl, so the test continues in a
+ * controlled manner.
+ */
+		"3:	larl	%[branch_addr],0\n"
+		"4:\n"
+
+/*
+ * Clang 15 doesn't like the if below, guard it s.t. we still have the assertion
+ * when compiling with GCC.
+ *
+ * s390x/ex.c:81:4: error: expected absolute expression
+ *                  "       .if (1b - 0b) != (3b - 2b)\n"
+ */
+#ifndef __clang__
+		"	.if (1b - 0b) != (3b - 2b)\n"
+		"	.error	\"right and wrong target must have same offset\"\n"
+		"	.endif\n"
+#endif
+		: [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();
+}
+
+/*
+ * LOAD ADDRESS RELATIVE LONG.
+ * If it is the target of an execute-type instruction, the address is relative
+ * to the LARL.
+ */
+static void test_larl(void)
+{
+	uint64_t target, addr;
+
+	report_prefix_push("LARL");
+	asm volatile ( ".pushsection .text.exrl_targets\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();
+}
+
+/* LOAD LOGICAL RELATIVE LONG.
+ * If it is the target of an execute-type instruction, the address is relative
+ * to the LLGFRL.
+ */
+static void test_llgfrl(void)
+{
+	uint64_t target, value;
+
+	report_prefix_push("LLGFRL");
+	asm volatile ( ".pushsection .text.exrl_targets\n"
+		"	.balign	4\n"
+		 //operand of llgfrl must be word aligned
+		"0:	llgfrl	%[value],0\n"
+		"	.popsection\n"
+
+		"	llgfrl	%[target],0b\n"
+		//align (pad with nop), in case the wrong operand is used
+		"	.balignw 4,0x0707\n"
+		"	exrl	0,0b\n"
+		: [target] "=d" (target),
+		  [value] "=d" (value)
+	);
+
+	report(target == value, "loaded correct value");
+	report_prefix_pop();
+}
+
+/*
+ * COMPARE RELATIVE LONG
+ * If it is the target of an execute-type instruction, the address is relative
+ * to the CRL.
+ */
+static void test_crl(void)
+{
+	uint32_t program_mask, cc, crl_word;
+
+	report_prefix_push("CRL");
+	asm volatile ( ".pushsection .text.exrl_targets\n"
+		 //operand of crl must be word aligned
+		 "	.balign	4\n"
+		"0:	crl	%[crl_word],0\n"
+		"	.popsection\n"
+
+		"	lrl	%[crl_word],0b\n"
+		//align (pad with nop), in case the wrong operand is used
+		"	.balignw 4,0x0707\n"
+		"	exrl	0,0b\n"
+		"	ipm	%[program_mask]\n"
+		: [program_mask] "=d" (program_mask),
+		  [crl_word] "=d" (crl_word)
+		:: "cc"
+	);
+
+	cc = program_mask >> 28;
+	report(!cc, "operand compared to is relative to CRL");
+	report_prefix_pop();
+}
+
+int main(int argc, char **argv)
+{
+	report_prefix_push("ex");
+	test_basr();
+	test_bras();
+	test_larl();
+	test_llgfrl();
+	test_crl();
+	report_prefix_pop();
+
+	return report_summary();
+}
diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
index d97eb5e..b61faf0 100644
--- a/s390x/unittests.cfg
+++ b/s390x/unittests.cfg
@@ -215,3 +215,6 @@ file = migration-skey.elf
 smp = 2
 groups = migration
 extra_params = -append '--parallel'
+
+[execute]
+file = ex.elf
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index ad7949c..a999f64 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -275,6 +275,7 @@ s390x-kvm:
   - ACCEL=kvm ./run_tests.sh
       selftest-setup intercept emulator sieve sthyi diag10 diag308 pfmf
       cmm vector gs iep cpumodel diag288 stsi sclp-1g sclp-3g css skrf sie
+      execute
       | tee results.txt
   - grep -q PASS results.txt && ! grep -q FAIL results.txt
  only:
-- 
2.39.2