[sw/test] Add a test for the CRT.
This test can, for now, catch the regression fixed by the previous
commit. However, this test is not a fail-safe, since the linker can
arrange symbols in a way that causes the test to spuriously pass.
Signed-off-by: Miguel Young de la Sota <mcyoung@google.com>
diff --git a/ci/run_verilator_pytest.sh b/ci/run_verilator_pytest.sh
index ff57239..372da74 100755
--- a/ci/run_verilator_pytest.sh
+++ b/ci/run_verilator_pytest.sh
@@ -17,6 +17,7 @@
TEST_TARGETS=(
"examples/hello_usbdev/hello_usbdev_sim_verilator.elf"
"tests/aes_test_sim_verilator.elf"
+ "tests/crt_test_sim_verilator.elf"
"tests/dif_plic_sanitytest_sim_verilator.elf"
"tests/dif_rv_timer_sanitytest_sim_verilator.elf"
"tests/dif_uart_sanitytest_sim_verilator.elf"
diff --git a/sw/device/tests/crt_test.c b/sw/device/tests/crt_test.c
new file mode 100644
index 0000000..f588509
--- /dev/null
+++ b/sw/device/tests/crt_test.c
@@ -0,0 +1,113 @@
+// Copyright lowRISC contributors.
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "sw/device/lib/arch/device.h"
+#include "sw/device/lib/base/log.h"
+#include "sw/device/lib/base/print.h"
+#include "sw/device/lib/base/stdasm.h"
+#include "sw/device/lib/runtime/check.h"
+#include "sw/device/lib/testing/test_status.h"
+#include "sw/device/lib/uart.h"
+
+// Symbols defined in sw/device/exts/common/flash_link.ld, which we use to
+// check that the CRT did what it was supposed to.
+extern char _bss_start;
+extern char _bss_end;
+extern char _data_start;
+extern char _data_end;
+extern char _data_init_start;
+
+// The addresses of the values above.
+static const uintptr_t bss_start_addr = (uintptr_t)&_bss_start;
+static const uintptr_t bss_end_addr = (uintptr_t)&_bss_end;
+static const uintptr_t data_start_addr = (uintptr_t)&_data_start;
+static const uintptr_t data_end_addr = (uintptr_t)&_data_end;
+static const uintptr_t data_init_start_addr = (uintptr_t)&_data_init_start;
+
+// Ensure that both .bss and .data are non-empty. The compiler will always keep
+// these symbols, since they're volatile.
+volatile char ensure_data_exists = 42;
+volatile char ensure_bss_exists;
+
+int main(int argc, char **argv) {
+ // NOTE: we cannot call any external functions until all checks of post-CRT
+ // state are complete; this is to ensure that our checks are not tainted by
+ // external functions.
+ //
+ // Among other things, this means we can't CHECK, since we can't initialize
+ // UART. Thus, any critical failures are handled by returning from main.
+ // To minimize the chance of things going wrong, we don't even bother placing
+ // the checks in their own function.
+
+ // Test core assumptions above the five addresses above. The test code
+ // must be able to assume these all hold.
+ //
+ // Note that performing these comparisons on their addresses is UB, and will
+ // cause this entire function to get deleted by the compiler.
+ if (&_bss_start > &_bss_end || &_data_start > &_data_end) {
+ // Something has gone terribly wrong and we have no hope of continuing the
+ // test, so we're going to return and let the test time out.
+ //
+ // The best method for debugging a failure like this is to stare at an
+ // instruction trace.
+ return 1;
+ }
+
+ // Ensure that .bss was *actually* zeroed at the start of execution. If it
+ // wasn't, we note the offset from _bss_start at which it wasn't.
+ char *bss = &_bss_start;
+ ptrdiff_t bss_len = &_bss_end - &_bss_start;
+ int bad_bss_index = -1;
+ for (int i = 0; i < bss_len; ++i) {
+ if (bss[i] != 0) {
+ bad_bss_index = i;
+ break;
+ }
+ }
+
+ // Similarly, ensure that .data has the values in the init section.
+ char *data = &_data_start;
+ char *data_init = &_data_init_start;
+ ptrdiff_t data_len = &_data_end - &_data_start;
+ int bad_data_index = -1;
+ for (int i = 0; i < data_len; ++i) {
+ if (data[i] != data_init[i]) {
+ bad_data_index = i;
+ break;
+ }
+ }
+
+ // End of post-CRT checks; begin actual assertions..
+ test_status_set(kTestStatusInTest);
+ // Initialize the UART to enable logging for non-DV simulation platforms.
+ if (kDeviceType != kDeviceSimDV) {
+ uart_init(kUartBaudrate);
+ base_set_stdout(uart_stdout);
+ }
+
+ CHECK(bss_start_addr % sizeof(uint32_t) == 0,
+ "_bss_start not word-aligned: 0x%08x", bss_start_addr);
+ CHECK(bss_end_addr % sizeof(uint32_t) == 0,
+ "_bss_end not word-aligned: 0x%08x", bss_end_addr);
+ CHECK(data_start_addr % sizeof(uint32_t) == 0,
+ "_data_start not word-aligned: 0x%08x", data_start_addr);
+ CHECK(data_end_addr % sizeof(uint32_t) == 0,
+ "_data_end not word-aligned: 0x%08x", data_end_addr);
+ CHECK(data_init_start_addr % sizeof(uint32_t) == 0,
+ "_data_init_start not word-aligned: 0x%08x", data_init_start_addr);
+
+ CHECK(bad_bss_index == -1, "found non-zero .bss byte at *0x%08x == 0x%02x",
+ bss_start_addr + bad_bss_index, (uint32_t)bss[bad_bss_index]);
+ CHECK(bad_data_index == -1,
+ "found bad .data byte at *0x%08x == 0x%02x, expected 0x%02x",
+ data_start_addr + bad_data_index, (uint32_t)data_init[bad_data_index]);
+
+ test_status_set(kTestStatusPassed);
+
+ // Unreachable code.
+ return 1;
+}
diff --git a/sw/device/tests/meson.build b/sw/device/tests/meson.build
index 512b613..e467d3c 100644
--- a/sw/device/tests/meson.build
+++ b/sw/device/tests/meson.build
@@ -87,3 +87,37 @@
)
endforeach
endforeach
+
+foreach device_name, device_lib : sw_lib_arch_core_devices
+ crt_test_elf = executable(
+ 'crt_test_' + device_name,
+ name_suffix: 'elf',
+ sources: ['crt_test.c'],
+ dependencies: [
+ riscv_crt,
+ device_lib,
+ sw_lib_irq_handlers,
+ sw_lib_testing_test_status,
+ # Explicitly do not pull in the test main; we need to run right after
+ # the CRT is done executing.
+ # sw_lib_testing_test_main,
+ ],
+ )
+
+ crt_test_embedded = custom_target(
+ 'crt_test_' + device_name,
+ command: make_embedded_target,
+ input: crt_test_elf,
+ output: make_embedded_target_outputs,
+ build_by_default: true,
+ )
+
+ custom_target(
+ 'crt_test_export_' + device_name,
+ command: export_embedded_target,
+ input: [crt_test_elf, crt_test_embedded],
+ output: 'crt_test_export_' + device_name,
+ build_always_stale: true,
+ build_by_default: true,
+ )
+endforeach
