[examples/sw] Add a pmp smoke test

examples/sw/simple_system/pmp_smoke_test/Makefile

@@ -0,0 +1,14 @@
+# Copyright lowRISC contributors.
+# Licensed under the Apache License, Version 2.0, see LICENSE for details.
+# SPDX-License-Identifier: Apache-2.0
+#
+# Generate a baremetal application
+
+# Name of the program $(PROGRAM).c will be added as a source file
+PROGRAM = pmp_smoke_test
+PROGRAM_DIR := $(shell dirname $(realpath $(lastword $(MAKEFILE_LIST))))
+# Any extra source files to include in the build. Use the upper case .S
+# extension for assembly files
+EXTRA_SRCS :=
+
+include ${PROGRAM_DIR}/../common/common.mk

examples/sw/simple_system/pmp_smoke_test/pmp_smoke_test.c

@@ -0,0 +1,26 @@
+// Copyright lowRISC contributors.
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+//
+// Basic smoke test for PMP. The test sets up a read-only PMP region then tries
+// to write to it. It is intended for use with an external checking method (such
+// as the Ibex co-simulation system) and does not report pass or fail.
+
+volatile unsigned int test_int = 10;
+
+// Locked read only for lowest region, NA4 matching
+#define TEST_PMPCFG0 0x91
+
+int main(int argc, char **argv) {
+  unsigned int pmpaddr0 = ((unsigned int)&test_int) >> 2;
+
+  __asm__ volatile(
+      "csrw pmpaddr0, %1\n"
+      "csrw pmpcfg0, %0\n"
+      :
+      : "r"(TEST_PMPCFG0), "r"(pmpaddr0));
+
+  test_int = 12;
+
+  return 0;
+}