kselftest/arm64: Provide a helper binary and "library" for SVE RDVL

SVE provides an instruction RDVL which reports the currently configured
vector length. In order to validate that our vector length configuration
interfaces are working correctly without having to build the C code for
our test programs with SVE enabled provide a trivial assembly library
with a C callable function that executes RDVL. Since these interfaces
also control behaviour on exec*() provide a trivial wrapper program which
reports the currently configured vector length on stdout, tests can use
this to verify that behaviour on exec*() is as expected.

In preparation for providing similar helper functionality for SME, the
Scalable Matrix Extension, which allows separately configured vector
lengths to be read back both the assembler function and wrapper binary
have SVE included in their name.

Signed-off-by: Mark Brown <[email protected]>
Reviewed-by: Dave Martin <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

5 files changed, 38 insertions, 1 deletions

diff --git a/tools/testing/selftests/arm64/fp/.gitignore b/tools/testing/selftests/arm64/fp/.gitignore
index d66f76d2a650..6b53a7b60fee 100644
--- a/tools/testing/selftests/arm64/fp/.gitignore
+++ b/tools/testing/selftests/arm64/fp/.gitignore
@@ -1,4 +1,5 @@
 fpsimd-test
+rdvl-sve
 sve-probe-vls
 sve-ptrace
 sve-test
diff --git a/tools/testing/selftests/arm64/fp/Makefile b/tools/testing/selftests/arm64/fp/Makefile
index a57009d3a0dc..ed62e7003b96 100644
--- a/tools/testing/selftests/arm64/fp/Makefile
+++ b/tools/testing/selftests/arm64/fp/Makefile
@@ -2,12 +2,16 @@
 
 CFLAGS += -I../../../../../usr/include/
 TEST_GEN_PROGS := sve-ptrace sve-probe-vls
-TEST_PROGS_EXTENDED := fpsimd-test fpsimd-stress sve-test sve-stress vlset
+TEST_PROGS_EXTENDED := fpsimd-test fpsimd-stress \
+	rdvl-sve \
+	sve-test sve-stress \
+	vlset
 
 all: $(TEST_GEN_PROGS) $(TEST_PROGS_EXTENDED)
 
 fpsimd-test: fpsimd-test.o
 	$(CC) -nostdlib $^ -o $@
+rdvl-sve: rdvl-sve.o rdvl.o
 sve-ptrace: sve-ptrace.o sve-ptrace-asm.o
 sve-probe-vls: sve-probe-vls.o
 sve-test: sve-test.o
diff --git a/tools/testing/selftests/arm64/fp/rdvl-sve.c b/tools/testing/selftests/arm64/fp/rdvl-sve.c
new file mode 100644
index 000000000000..7f8a13a18f5d
--- /dev/null
+++ b/tools/testing/selftests/arm64/fp/rdvl-sve.c
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <stdio.h>
+
+#include "rdvl.h"
+
+int main(void)
+{
+	int vl = rdvl_sve();
+
+	printf("%d\n", vl);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/arm64/fp/rdvl.S b/tools/testing/selftests/arm64/fp/rdvl.S
new file mode 100644
index 000000000000..c916c1c9defd
--- /dev/null
+++ b/tools/testing/selftests/arm64/fp/rdvl.S
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (C) 2021 ARM Limited.
+
+.arch_extension sve
+
+.globl rdvl_sve
+rdvl_sve:
+	hint	34			// BTI C
+	rdvl	x0, #1
+	ret
diff --git a/tools/testing/selftests/arm64/fp/rdvl.h b/tools/testing/selftests/arm64/fp/rdvl.h
new file mode 100644
index 000000000000..7c9d953fc9e7
--- /dev/null
+++ b/tools/testing/selftests/arm64/fp/rdvl.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef RDVL_H
+#define RDVL_H
+
+int rdvl_sve(void);
+
+#endif