# Tutorial 12 - Integrated Testing ## tl;dr - We implement our own integrated test framework using `Rust`'s [custom_test_frameworks] feature by enabling `Unit Tests` and `Integration Tests` using `QEMU`. - It is also possible to have test automation for I/O with the kernel's `console` (provided over `UART` in our case). That is, sending strings/characters to the console and expecting specific answers in return. - The already existing basic `boot test` remains unchanged. ## Table of Contents - [Introduction](#introduction) - [Challenges](#challenges) * [Acknowledgements](#acknowledgements) - [Implementation](#implementation) * [Test Organization](#test-organization) * [Enabling `custom_test_frameworks` for Unit Tests](#enabling-custom_test_frameworks-for-unit-tests) + [The Unit Test Runner](#the-unit-test-runner) + [Calling the Test `main()` Function](#calling-the-test-main-function) * [Quitting QEMU with user-defined Exit Codes](#quitting-qemu-with-user-defined-exit-codes) + [Exiting Unit Tests](#exiting-unit-tests) * [Controlling Test Kernel Execution](#controlling-test-kernel-execution) + [Wrapping QEMU Test Execution](#wrapping-qemu-test-execution) * [Writing Unit Tests](#writing-unit-tests) * [Integration Tests](#integration-tests) + [Test Harness](#test-harness) + [No Test Harness](#no-test-harness) + [Overriding Panic Behavior](#overriding-panic-behavior) * [Console Tests](#console-tests) - [Test it](#test-it) - [Diff to previous](#diff-to-previous) ## Introduction Through the course of the previous tutorials, we silently started to adopt a kind of anti-pattern: Using the kernel's main function to not only boot the target, but also test or showcase functionality. For example: - Stalling execution during boot to test the kernel's timekeeping code by spinning for 1 second. - Willingly causing exceptions to see the exception handler running. The feature set of the kernel is now rich enough so that it makes sense to introduce proper integrated testing modeled after Rust's [native testing framework]. This tutorial extends our single existing kernel test with three new testing facilities: - Classic `Unit Tests`. - [Integration Tests] (self-contained tests stored in the `$CRATE/tests/` directory). - `Console I/O Tests`. These are integration tests acting on external stimuli - aka `console` input. Sending strings/characters to the console and expecting specific answers in return. [native testing framework]: https://doc.rust-lang.org/book/ch11-00-testing.html ## Challenges Testing Rust `#![no_std]` code like our kernel is, at the point of writing this tutorial, not an easy endeavor. The short version is: We cannot use Rust's [native testing framework] straight away. Utilizing the `#[test]` attribute macro and running `cargo test` would throw compilation errors, because there are dependencies on the standard library. [native testing framework]: https://doc.rust-lang.org/book/ch11-00-testing.html We have to fall back to Rust's unstable [custom_test_frameworks] feature. It relieves us from dependencies on the standard library, but comes at the cost of having a reduced feature set. Instead of annotating functions with `#[test]`, the `#[test_case]` attribute must be used. Additionally, we need to write a `test_runner` function, which is supposed to execute all the functions annotated with `#[test_case]`. This is barely enough to get `Unit Tests` running, though. There will be some more challenges that need be solved for getting `Integration Tests` running as well. Please note that for automation purposes, all testing will be done in `QEMU` and not on real hardware. [custom_test_frameworks]: https://doc.rust-lang.org/unstable-book/language-features/custom-test-frameworks.html [Integration Tests]: https://doc.rust-lang.org/book/ch11-03-test-organization.html#integration-tests ### Acknowledgements On this occasion, kudos to [@phil-opp] for his x86-based [testing] article. It helped a lot in putting together this tutorial. Please go ahead and read it for a different perspective and additional insights. [testing]: https://os.phil-opp.com/testing ## Implementation We introduce two new `Makefile` targets: ```console $ make test_unit $ make test_integration ``` In essence, the `make test_*` targets will execute `cargo test` instead of `cargo rustc`. The details will be explained in due course. The rest of the tutorial will explain as chronologically as possible what happens when `make test_*` aka `cargo test` runs. Please note that the new targets are added to the existing `make test` target, so this is now your one-stop target to execute all possible tests for the kernel: ```Makefile test: test_boot test_unit test_integration ``` ### Test Organization Until now, our kernel was a so-called `binary crate`. As [explained in the official Rust book], this crate type disallows having `integration tests`. Quoting the book: [explained in the official Rust book]: https://doc.rust-lang.org/book/ch11-03-test-organization.html#integration-tests-for-binary-crates > If our project is a binary crate that only contains a _src/main.rs_ file and doesn’t have a > _src/lib.rs_ file, we can’t create integration tests in the _tests_ directory and bring functions > defined in the _src/main.rs_ file into scope with a `use` statement. Only library crates expose > functions that other crates can use; binary crates are meant to be run on their own. > This is one of the reasons Rust projects that provide a binary have a straightforward > _src/main.rs_ file that calls logic that lives in the _src/lib.rs_ file. Using that structure, > integration tests _can_ test the library crate with `use` to make the important functionality > available. If the important functionality works, the small amount of code in the _src/main.rs_ > file will work as well, and that small amount of code doesn’t need to be tested. So let's do that first: We add a `lib.rs` to our crate that aggregates and exports the lion's share of the kernel code. The `main.rs` file is stripped down to the minimum. It only keeps the `kernel_init() -> !` and `kernel_main() -> !` functions, everything else is brought into scope with `use` statements. Since it is not possible to use `kernel` as the name for both the library and the binary part of the crate, new entries in `Cargo.toml` are needed to differentiate the names. What's more, `cargo test` would try to compile and run `unit tests` for both. In our case, it will be sufficient to have all the unit test code in `lib.rs`, so test generation for `main.rs` can be disabled in `Cargo.toml` as well through the `test` flag: ```toml [lib] name = "libkernel" test = true [[bin]] name = "kernel" test = false ``` ### Enabling `custom_test_frameworks` for Unit Tests In `lib.rs`, we add the following headers to get started with `custom_test_frameworks`: ```rust // Testing #![cfg_attr(test, no_main)] #![feature(custom_test_frameworks)] #![reexport_test_harness_main = "test_main"] #![test_runner(crate::test_runner)] ``` Since this is a library now, we do not keep the `#![no_main]` inner attribute that `main.rs` has, because a library has no `main()` entry function, so the attribute does not apply. When compiling for testing, though, it is still needed. The reason is that `cargo test` basically turns `lib.rs` into a binary again by inserting a generated `main()` function (which is then calling a function that runs all the unit tests, but more about that in a second...). However, since our kernel code [overrides the compiler-inserted `main` shim] by way of using `#![no_main]`, we need the same when `cargo test` is producing its test kernel binary. After all, what we want is a minimal kernel that boots on the target and runs its own unit tests. Therefore, we conditionally set this attribute (`#![cfg_attr(test, no_main)]`) when the `test` flag is set, which it is when `cargo test` runs. [overrides the compiler-inserted `main` shim]: https://doc.rust-lang.org/unstable-book/language-features/lang-items.html?highlight=no_main#writing-an-executable-without-stdlib #### The Unit Test Runner The `#![test_runner(crate::test_runner)]` attribute declares the path of the test runner function that we are supposed to provide. This is the one that will be called by the `cargo test` generated `main()` function. Here is the implementation in `lib.rs`: ```rust /// The default runner for unit tests. pub fn test_runner(tests: &[&test_types::UnitTest]) { // This line will be printed as the test header. println!("Running {} tests", tests.len()); for (i, test) in tests.iter().enumerate() { print!("{:>3}. {:.<58}", i + 1, test.name); // Run the actual test. (test.test_func)(); // Failed tests call panic!(). Execution reaches here only if the test has passed. println!("[ok]") } } ``` The function signature shows that `test_runner` takes one argument: A slice of `test_types::UnitTest` references. This type definition lives in an external crate stored at `$ROOT/test_types`. It is external because the type is also needed for a self-made [procedural macro] that we'll use to write unit tests, and procedural macros _have_ to live in their own crate. So to avoid a circular dependency between kernel and proc-macro, this split was needed. Anyways, here is the type definition: [procedural macro]: https://doc.rust-lang.org/reference/procedural-macros.html ```rust /// Unit test container. pub struct UnitTest { /// Name of the test. pub name: &'static str, /// Function pointer to the test. pub test_func: fn(), } ``` A `UnitTest` provides a name and a classic function pointer to the unit test function. The `test_runner` just iterates over the slice, prints the respective test's name and calls the test function. The convetion is that as long as the test function does not `panic!`, the test was successful. #### Calling the Test `main()` Function The last of the attributes we added is `#![reexport_test_harness_main = "test_main"]`. Remember that our kernel uses the `no_main` attribute, and that we also set it for the test compilation. We did that because we wrote our own `_start()` function, which kicks off the following call chain during kernel boot: | | Function | File | | - | - | - | | 1. | `_start()` | The library's `boot.s` | | 2. | (some more aarch64 code) | The library's `boot.rs` | | 3. | `kernel_init()` | `main.rs` | | 4. | `kernel_main()` | `main.rs` | A function named `main` is never called. Hence, the `main()` function generated by `cargo test` would be silently dropped, and therefore the tests would never be executed. As you can see, the first function getting called in our carved-out `main.rs` is `kernel_init()`. So in order to get the tests to execute, we add a test-environment version of `kernel_init()` to `lib.rs` as well (conditional compilation ensures it is only present when the test flag is set), and call the `cargo test` generated `main()` function from there. This is where `#![reexport_test_harness_main = "test_main"]` finally comes into picture. It declares the name of the generated main function so that we can manually call it. Here is the final implementation in `lib.rs`: ```rust /// The `kernel_init()` for unit tests. #[cfg(test)] #[no_mangle] unsafe fn kernel_init() -> ! { exception::handling_init(); bsp::console::qemu_bring_up_console(); test_main(); cpu::qemu_exit_success() } ``` Note the call to `bsp::console::qemu_bring_up_console()`. Since we are running all our tests inside `QEMU`, we need to ensure that whatever peripheral implements the kernel's `console` interface is initialized, so that we can print from our tests. If you recall [tutorial 03], bringing up peripherals in `QEMU` might not need the full initialization as is needed on real hardware (setting clocks, config registers, etc...) due to the abstractions in `QEMU`'s emulation code. So this is an opportunity to cut down on setup code. [tutorial 03]: ../03_hacky_hello_world As a matter of fact, for the `Raspberrys`, nothing needs to be done, so the function is empy. But this might be different for other hardware emulated by `QEMU`, so it makes sense to introduce the function now to make it easier in case new `BSPs` are added to the kernel in the future. Next, the reexported `test_main()` is called, which will call our `test_runner()` which finally prints the unit test names and executes them. ### Quitting QEMU with user-defined Exit Codes Let's recap where we are right now: We've enabled `custom_test_frameworks` in `lib.rs` to a point where, when using a `make test_unit` target, the code gets compiled to a test kernel binary that eventually executes all the (yet-to-be-defined) `UnitTest` instances by executing all the way from `_start()` to our `test_runner()` function. Through mechanisms that are explained later, `cargo` will now instantiate a `QEMU` process that exectues this test kernel. The question now is: How is test success/failure communicated to `cargo`? Answer: `cargo` inspects `QEMU`'s [exit status]: - `0` translates to testing was successful. - `non-0` means failure. Hence, we need a clever trick now so that our Rust kernel code can get `QEMU` to exit itself with an exit status that the kernel code supplies. In [@phil-opp]'s testing article, you [learned how to do this] for `x86 QEMU` systems by using a special `ISA` debug-exit device. Unfortunately, we can't have that one for our `aarch64` system because it is not compatible. In our case, we can leverage the ARM [semihosting] emulation of `QEMU` and do a `SYS_EXIT` semihosting call with an additional parameter for the exit code. I've written a separate crate, [qemu-exit], to do this. So let us import it and utilize it in `_arch/aarch64/cpu.rs` to provide the following exit calls for the kernel: ```rust //-------------------------------------------------------------------------------------------------- // Testing //-------------------------------------------------------------------------------------------------- #[cfg(feature = "test_build")] use qemu_exit::QEMUExit; #[cfg(feature = "test_build")] const QEMU_EXIT_HANDLE: qemu_exit::AArch64 = qemu_exit::AArch64::new(); /// Make the host QEMU binary execute `exit(1)`. #[cfg(feature = "test_build")] pub fn qemu_exit_failure() -> ! { QEMU_EXIT_HANDLE.exit_failure() } /// Make the host QEMU binary execute `exit(0)`. #[cfg(feature = "test_build")] pub fn qemu_exit_success() -> ! { QEMU_EXIT_HANDLE.exit_success() } ``` [Click here] in case you are interested in the implementation. Note that for the functions to work, the `-semihosting` flag must be added to the `QEMU` invocation. You might have also noted the `#[cfg(feature = "test_build")]`. In the `Makefile`, we ensure that this feature is only enabled when `cargo test` runs. This way, it is ensured that testing-specific code is conditionally compiled only for testing. [exit status]: https://en.wikipedia.org/wiki/Exit_status [@phil-opp]: https://github.com/phil-opp [learned how to do this]: https://os.phil-opp.com/testing/#exiting-qemu [semihosting]: https://static.docs.arm.com/100863/0200/semihosting.pdf [qemu-exit]: https://github.com/andre-richter/qemu-exit [Click here]: https://github.com/andre-richter/qemu-exit/blob/master/src/aarch64.rs #### Exiting Unit Tests Unit test failure shall be triggered by the `panic!` macro, either directly or by way of using `assert!` macros. Until now, our `panic!` implementation finally called `cpu::wait_forever()` to safely park the panicked CPU core in a busy loop. This can't be used for the unit tests, because `cargo` would wait forever for `QEMU` to exit and stall the whole test run. Again, conditional compilation is used to differentiate between a release and testing version of how a `panic!` concludes: ```rust /// The point of exit for `libkernel`. /// /// It is linked weakly, so that the integration tests can overload its standard behavior. #[linkage = "weak"] #[no_mangle] fn _panic_exit() -> ! { #[cfg(not(feature = "test_build"))] { cpu::wait_forever() } #[cfg(feature = "test_build")] { cpu::qemu_exit_failure() } } ``` In case _none_ of the unit tests panicked, `lib.rs`'s `kernel_init()` calls `cpu::qemu_exit_success()` to successfully conclude the unit test run. ### Controlling Test Kernel Execution Now is a good time to catch up on how the test kernel binary is actually being executed. Normally, `cargo test` would try to execute the compiled binary as a normal child process. This would fail horribly because we build a kernel, and not a userspace process. Also, chances are high that you sit in front of an `x86` machine, whereas the RPi kernel is `AArch64`. Therefore, we need to install some hooks that make sure the test kernel gets executed inside `QEMU`, quite like it is done for the existing `make qemu` target that is in place since `tutorial 1`. The first step is to add a new file to the project, `.cargo/config.toml`: ```toml [target.'cfg(target_os = "none")'] runner = "target/kernel_test_runner.sh" ``` Instead of executing a compilation result directly, the `runner` flag will instruct `cargo` to delegate the execution. Using the setting depicted above, `target/kernel_test_runner.sh` will be executed and given the full path to the compiled test kernel as the first command line argument. The file `kernel_test_runner.sh` does not exist by default. We generate it on demand when one of the `make test_*` targets is called: ```Makefile ##------------------------------------------------------------------------------ ## Helpers for unit and integration test targets ##------------------------------------------------------------------------------ define KERNEL_TEST_RUNNER #!/usr/bin/env bash TEST_ELF=$$(echo $$1 | sed -e 's/.*target/target/g') TEST_BINARY=$$(echo $$1.img | sed -e 's/.*target/target/g') $(OBJCOPY_CMD) $$TEST_ELF $$TEST_BINARY $(DOCKER_TEST) $(EXEC_TEST_DISPATCH) $(EXEC_QEMU) $(QEMU_TEST_ARGS) -kernel $$TEST_BINARY endef export KERNEL_TEST_RUNNER define test_prepare @mkdir -p target @echo "$$KERNEL_TEST_RUNNER" > target/kernel_test_runner.sh @chmod +x target/kernel_test_runner.sh endef test_unit test_integration: FEATURES += --features test_build ##------------------------------------------------------------------------------ ## Run unit test(s) ##------------------------------------------------------------------------------ test_unit: $(call colorecho, "\nCompiling unit test(s) - $(BSP)") $(call test_prepare) @RUSTFLAGS="$(RUSTFLAGS_PEDANTIC)" $(TEST_CMD) --lib ``` It first does the standard `objcopy` step to strip the `ELF` down to a raw binary. Just like in all the other Makefile targets. Next, the script generates a relative path from the absolute path provided to it by `cargo`, and finally compiles a `docker` command to execute the test kernel. For reference, here it is fully resolved for an `RPi3 BSP`: ```bash docker run --rm -v /opt/rust-raspberrypi-OS-tutorials/12_integrated_testing:/work/tutorial -w /work/tutorial -v /opt/rust-raspberrypi-OS-tutorials/12_integrated_testing/../common:/work/common rustembedded/osdev-utils ruby ../common/tests/dispatch.rb qemu-system-aarch64 -M raspi3 -serial stdio -display none -semihosting -kernel $TEST_BINARY ``` This command is quite similar to the one used in the `make test_boot` target that we have since `tutorial 3`. However, we never bothered explaining it, so lets take a closer look this time. One of the key ingredients is that we execute this script: `ruby ../common/tests/dispatch.rb`. #### Wrapping QEMU Test Execution `dispatch.rb` is a [Ruby] script which first determines what kind of test is due by inspecting the `QEMU`-command that was given to it. In case of `unit tests`, we are only interested if they all executed successfully, which can be checked by inspecting `QEMU`'s exit code. So the script takes the provided qemu command it got from `ARGV`, and creates and runs an instance of `ExitCodeTest`: ```ruby require_relative 'boot_test' require_relative 'console_io_test' require_relative 'exit_code_test' qemu_cmd = ARGV.join(' ') binary = ARGV.last test_name = binary.gsub(%r{.*deps/}, '').split('-')[0] case test_name when 'kernel8.img' load 'tests/boot_test_string.rb' # provides 'EXPECTED_PRINT' BootTest.new(qemu_cmd, EXPECTED_PRINT).run # Doesn't return when 'libkernel' ExitCodeTest.new(qemu_cmd, 'Kernel library unit tests').run # Doesn't return ``` The easy case is `QEMU` existing by itself by means of `aarch64::exit_success()` or `aarch64::exit_failure()`. But the script can also catch the case of a test that gets stuck, e.g. in an unintentional busy loop or a crash. If `ExitCodeTest` does not observe any output of the test kernel for `MAX_WAIT_SECS`, it cancels the execution and marks the test as failed. Test success or failure is finally reported back to `cargo`. Here is the essential part happening in `class ExitCodeTest` (If `QEMU` exits itself, an `EOFError` is thrown): ```ruby def run_concrete_test io = IO.popen(@qemu_cmd) Timeout.timeout(MAX_WAIT_SECS) do @test_output << io.read_nonblock(1024) while IO.select([io]) end rescue EOFError io.close @test_error = $CHILD_STATUS.to_i.zero? ? false : 'QEMU exit status != 0' rescue Timeout::Error @test_error = 'Timed out waiting for test' rescue StandardError => e @test_error = e.message ensure post_process_output end ``` Please note that `dispatch.rb` and all its dependencies live in the shared folder `../common/tests/`. [Ruby]: https://www.ruby-lang.org/ ### Writing Unit Tests Alright, that's a wrap for the whole chain from `make test_unit` all the way to reporting the test exit status back to `cargo test`. It is a lot to digest already, but we haven't even learned to write `Unit Tests` yet. In essence, it is almost like in `std` environments, with the difference that `#[test]` can't be used, because it is part of the standard library. The `no_std` replacement attribute provided by `custom_test_frameworks` is `#[test_case]`. You can put `#[test_case]` before functions, constants or statics (you have to decide for one and stick with it). Each attributed item is added to the "list" that is then passed to the `test_runner` function. As you learned earlier, we decided that our tests shall be instances of `test_types::UnitTest`. Here is the type definition again: ```rust /// Unit test container. pub struct UnitTest { /// Name of the test. pub name: &'static str, /// Function pointer to the test. pub test_func: fn(), } ``` So what we could do now is write something like: ```rust #[cfg(test)] mod tests { use super::*; #[test_case] const TEST1: test_types::UnitTest = test_types::UnitTest { name: "test_runner_executes_in_kernel_mode", test_func: || { let (level, _) = current_privilege_level(); assert!(level == PrivilegeLevel::Kernel) }, }; } ``` Since this is a bit boiler-platy with the const and name definition, let's write a [procedural macro] named `#[kernel_test]` to simplify this. It should work this way: 1. Must be put before functions that take no arguments and return nothing. 1. Automatically constructs a `const UnitTest` from attributed functions like shown above by: 1. Converting the function name to the `name` member of the `UnitTest` struct. 1. Populating the `test_func` member with a closure that executes the body of the attributed function. For the sake of brevity, we're not going to discuss the macro implementation. [The source is in the test-macros crate] if you're interested in it. Using the macro, the example shown before now boils down to this (this is now an actual example from [exception.rs]: [procedural macro]: https://doc.rust-lang.org/reference/procedural-macros.html [The source is in the test-macros crate]: test-macros/src/lib.rs [exception.rs]: src/exception.rs ```rust #[cfg(test)] mod tests { use super::*; use test_macros::kernel_test; /// Libkernel unit tests must execute in kernel mode. #[kernel_test] fn test_runner_executes_in_kernel_mode() { let (level, _) = current_privilege_level(); assert!(level == PrivilegeLevel::Kernel) } } ``` Note that since proc macros need to live in their own crates, we need to create a new one at `$ROOT/test-macros` and save it there. Aaaaaand that's how you write unit tests. We're finished with that part for good now :raised_hands:. ### Integration Tests We are still not done with the tutorial, though :scream:. Integration tests need some special attention here and there too. As you already learned, they live in `$CRATE/tests/`. Each `.rs` file in there gets compiled into its own test kernel binary and executed separately by `cargo test`. The code in the integration tests includes the library part of our kernel (`libkernel`) through `use` statements. Also note that the entry point for each `integration test` must be the `kernel_init()` function again, just like in the `unit test` case. #### Test Harness By default, `cargo test` will pull in the test harness (that's the official name for the generated `main()` function) into integration tests as well. This gives you a further means of partitioning your test code into individual chunks. For example, take a look at `tests/01_timer_sanity.rs`: ```rust //! Timer sanity tests. #![feature(custom_test_frameworks)] #![no_main] #![no_std] #![reexport_test_harness_main = "test_main"] #![test_runner(libkernel::test_runner)] use core::time::Duration; use libkernel::{bsp, cpu, exception, time, time::interface::TimeManager}; use test_macros::kernel_test; #[no_mangle] unsafe fn kernel_init() -> ! { exception::handling_init(); bsp::console::qemu_bring_up_console(); // Depending on CPU arch, some timer bring-up code could go here. Not needed for the RPi. test_main(); cpu::qemu_exit_success() } /// Simple check that the timer is running. #[kernel_test] fn timer_is_counting() { assert!(time::time_manager().uptime().as_nanos() > 0) } /// Timer resolution must be sufficient. #[kernel_test] fn timer_resolution_is_sufficient() { assert!(time::time_manager().resolution().as_nanos() < 100) } ``` Note how the `test_runner` from `libkernel` is pulled in through `#![test_runner(libkernel::test_runner)]`. #### No Test Harness For some tests, however, it is not needed to have the harness, because there is no need or possibility to partition the test into individual pieces. In this case, all the test code can live in `kernel_init()`, and harness generation can be turned off through `Cargo.toml`. This tutorial introduces two tests that don't need a harness. Here is how harness generation is turned off for them: ```toml # List of tests without harness. [[test]] name = "00_console_sanity" harness = false [[test]] name = "02_exception_sync_page_fault" harness = false ``` #### Overriding Panic Behavior Did you notice the `#[linkage = "weak"]` attribute some chapters earlier at the `_panic_exit()` function? This marks the function in `lib.rs` as a [weak symbol]. Let's look at it again: ```rust /// The point of exit for `libkernel`. /// /// It is linked weakly, so that the integration tests can overload its standard behavior. #[linkage = "weak"] #[no_mangle] fn _panic_exit() -> ! { #[cfg(not(feature = "test_build"))] { cpu::wait_forever() } #[cfg(feature = "test_build")] { cpu::qemu_exit_failure() } } ``` [weak symbol]: https://en.wikipedia.org/wiki/Weak_symbol This enables integration tests in `$CRATE/tests/` to override this function according to their needs. This is useful, because depending on the kind of test, a `panic!` could mean success or failure. For example, `tests/02_exception_sync_page_fault.rs` is intentionally causing a page fault, so the wanted outcome is a `panic!`. Here is the whole test (minus some inline comments): ```rust //! Page faults must result in synchronous exceptions. #![feature(format_args_nl)] #![no_main] #![no_std] mod panic_exit_success; use libkernel::{bsp, cpu, exception, memory, println}; #[no_mangle] unsafe fn kernel_init() -> ! { use memory::mmu::interface::MMU; exception::handling_init(); bsp::console::qemu_bring_up_console(); // This line will be printed as the test header. println!("Testing synchronous exception handling by causing a page fault"); if let Err(string) = memory::mmu::mmu().enable_mmu_and_caching() { println!("MMU: {}", string); cpu::qemu_exit_failure() } println!("Writing beyond mapped area to address 9 GiB..."); let big_addr: u64 = 9 * 1024 * 1024 * 1024; core::ptr::read_volatile(big_addr as *mut u64); // If execution reaches here, the memory access above did not cause a page fault exception. cpu::qemu_exit_failure() } ``` The `_panic_exit()` version that makes `QEMU` return `0` (indicating test success) is pulled in by `mod panic_exit_success;`, and it will take precedence over the `weak` version from `lib.rs`. ### Console Tests As the kernel or OS grows, it will be more and more interesting to test user/kernel interaction through the serial console. That is, sending strings/characters to the console and expecting specific answers in return. The `dispatch.rb` wrapper script provides infrastructure to recognize and dispatch console I/O tests with little overhead. It basically works like this: 1. For each integration test, check if a companion file to the `.rs` test file exists. - A companion file has the same name, but ends in `.rb`. - The companion file contains one or more console I/O subtests. 1. If it exists, load the file to dynamically import the console subtests. 1. Create a `ConsoleIOTest` instance and run it. - This first spawns `QEMU` and attaches to `QEMU`'s serial console emulation. - Then it runs all console subtests on it. Here is an excerpt from `00_console_sanity.rb` showing a subtest that does a handshake with the kernel over the console: ```ruby # Verify sending and receiving works as expected. class TxRxHandshake def name 'Transmit and Receive handshake' end def run(qemu_out, qemu_in) qemu_in.write_nonblock('ABC') raise ExpectTimeoutError if qemu_out.expect('OK1234', TIMEOUT_SECS).nil? end end ``` The subtest first sends `"ABC"` over the console to the kernel, and then expects to receive `"OK1234"` back. On the kernel side, it looks like this in `00_console_sanity.rs`: ```rust #![feature(format_args_nl)] #![no_main] #![no_std] use libkernel::{bsp, console, exception, print}; #[no_mangle] unsafe fn kernel_init() -> ! { use bsp::console::console; use console::interface::*; exception::handling_init(); bsp::console::qemu_bring_up_console(); // Handshake assert_eq!(console().read_char(), 'A'); assert_eq!(console().read_char(), 'B'); assert_eq!(console().read_char(), 'C'); print!("OK1234"); ``` ## Test it Believe it or not, that is all. There are four ways you can run tests now: 1. `make test` will run all tests back-to-back. That is, the ever existing `boot test` first, then `unit tests`, then `integration tests`. 1. `make test_unit` will run `libkernel`'s unit tests. 1. `make test_integration` will run all integration tests back-to-back. 1. `TEST=TEST_NAME make test_integration` will run a specficic integration test. - For example, `TEST=01_timer_sanity make test_integration` ```console $ make test [...] Running unittests (target/aarch64-unknown-none-softfloat/release/deps/libkernel-142a8d94bc9c615a) ------------------------------------------------------------------- 🦀 Running 6 tests ------------------------------------------------------------------- 1. virt_mem_layout_sections_are_64KiB_aligned................[ok] 2. virt_mem_layout_has_no_overlaps...........................[ok] 3. test_runner_executes_in_kernel_mode.......................[ok] 4. kernel_tables_in_bss......................................[ok] 5. size_of_tabledescriptor_equals_64_bit.....................[ok] 6. size_of_pagedescriptor_equals_64_bit......................[ok] ------------------------------------------------------------------- ✅ Success: Kernel library unit tests ------------------------------------------------------------------- Compiling integration test(s) - rpi3 Finished release [optimized] target(s) in 0.00s Running tests/00_console_sanity.rs (target/aarch64-unknown-none-softfloat/release/deps/00_console_sanity-c06130838f14dbff) ------------------------------------------------------------------- 🦀 Running 3 console I/O tests ------------------------------------------------------------------- 1. Transmit and Receive handshake............................[ok] 2. Transmit statistics.......................................[ok] 3. Receive statistics........................................[ok] ------------------------------------------------------------------- ✅ Success: 00_console_sanity.rs ------------------------------------------------------------------- Running tests/01_timer_sanity.rs (target/aarch64-unknown-none-softfloat/release/deps/01_timer_sanity-62a954d22239d1a3) ------------------------------------------------------------------- 🦀 Running 3 tests ------------------------------------------------------------------- 1. timer_is_counting.........................................[ok] 2. timer_resolution_is_sufficient............................[ok] 3. spin_accuracy_check_1_second..............................[ok] ------------------------------------------------------------------- ✅ Success: 01_timer_sanity.rs ------------------------------------------------------------------- Running tests/02_exception_sync_page_fault.rs (target/aarch64-unknown-none-softfloat/release/deps/02_exception_sync_page_fault-2d8ec603ef1c4d8e) ------------------------------------------------------------------- 🦀 Testing synchronous exception handling by causing a page fault ------------------------------------------------------------------- Writing beyond mapped area to address 9 GiB... Kernel panic: CPU Exception! FAR_EL1: 0x0000000240000000 ESR_EL1: 0x96000004 [...] ------------------------------------------------------------------- ✅ Success: 02_exception_sync_page_fault.rs ------------------------------------------------------------------- ``` ## Diff to previous ```diff diff -uNr 11_exceptions_part1_groundwork/.cargo/config.toml 12_integrated_testing/.cargo/config.toml --- 11_exceptions_part1_groundwork/.cargo/config.toml +++ 12_integrated_testing/.cargo/config.toml @@ -0,0 +1,2 @@ +[target.'cfg(target_os = "none")'] +runner = "target/kernel_test_runner.sh" diff -uNr 11_exceptions_part1_groundwork/Cargo.toml 12_integrated_testing/Cargo.toml --- 11_exceptions_part1_groundwork/Cargo.toml +++ 12_integrated_testing/Cargo.toml @@ -1,6 +1,6 @@ [package] name = "mingo" -version = "0.11.0" +version = "0.12.0" authors = ["Andre Richter "] edition = "2018" @@ -11,21 +11,46 @@ default = [] bsp_rpi3 = ["tock-registers"] bsp_rpi4 = ["tock-registers"] - -[[bin]] -name = "kernel" -path = "src/main.rs" +test_build = ["qemu-exit"] ##-------------------------------------------------------------------------------------------------- ## Dependencies ##-------------------------------------------------------------------------------------------------- [dependencies] +test-types = { path = "test-types" } # Optional dependencies tock-registers = { version = "0.7.x", default-features = false, features = ["register_types"], optional = true } +qemu-exit = { version = "2.x.x", optional = true } # Platform specific dependencies [target.'cfg(target_arch = "aarch64")'.dependencies] cortex-a = { version = "6.x.x" } +##-------------------------------------------------------------------------------------------------- +## Testing +##-------------------------------------------------------------------------------------------------- + +[dev-dependencies] +test-macros = { path = "test-macros" } + +# Unit tests are done in the library part of the kernel. +[lib] +name = "libkernel" +test = true + +# Disable unit tests for the kernel binary. +[[bin]] +name = "kernel" +path = "src/main.rs" +test = false + +# List of tests without harness. +[[test]] +name = "00_console_sanity" +harness = false + +[[test]] +name = "02_exception_sync_page_fault" +harness = false diff -uNr 11_exceptions_part1_groundwork/Makefile 12_integrated_testing/Makefile --- 11_exceptions_part1_groundwork/Makefile +++ 12_integrated_testing/Makefile @@ -14,6 +14,13 @@ # Default to a serial device name that is common in Linux. DEV_SERIAL ?= /dev/ttyUSB0 +# Optional integration test name. +ifdef TEST + TEST_ARG = --test $(TEST) +else + TEST_ARG = --test '*' +endif + ##-------------------------------------------------------------------------------------------------- @@ -27,6 +34,7 @@ QEMU_BINARY = qemu-system-aarch64 QEMU_MACHINE_TYPE = raspi3 QEMU_RELEASE_ARGS = -serial stdio -display none + QEMU_TEST_ARGS = $(QEMU_RELEASE_ARGS) -semihosting OBJDUMP_BINARY = aarch64-none-elf-objdump NM_BINARY = aarch64-none-elf-nm READELF_BINARY = aarch64-none-elf-readelf @@ -40,6 +48,7 @@ QEMU_BINARY = qemu-system-aarch64 QEMU_MACHINE_TYPE = QEMU_RELEASE_ARGS = -serial stdio -display none + QEMU_TEST_ARGS = $(QEMU_RELEASE_ARGS) -semihosting OBJDUMP_BINARY = aarch64-none-elf-objdump NM_BINARY = aarch64-none-elf-nm READELF_BINARY = aarch64-none-elf-readelf @@ -73,6 +82,7 @@ DOC_CMD = cargo doc $(COMPILER_ARGS) CLIPPY_CMD = cargo clippy $(COMPILER_ARGS) CHECK_CMD = cargo check $(COMPILER_ARGS) +TEST_CMD = cargo test $(COMPILER_ARGS) OBJCOPY_CMD = rust-objcopy \ --strip-all \ -O binary @@ -236,11 +246,11 @@ ##-------------------------------------------------------------------------------------------------- ## Testing targets ##-------------------------------------------------------------------------------------------------- -.PHONY: test test_boot +.PHONY: test test_boot test_unit test_integration ifeq ($(QEMU_MACHINE_TYPE),) # QEMU is not supported for the board. -test_boot test : +test_boot test_unit test_integration test: $(call colorecho, "\n$(QEMU_MISSING_STRING)") else # QEMU is supported. @@ -252,6 +262,45 @@ $(call colorecho, "\nBoot test - $(BSP)") @$(DOCKER_TEST) $(EXEC_TEST_DISPATCH) $(EXEC_QEMU) $(QEMU_RELEASE_ARGS) -kernel $(KERNEL_BIN) -test: test_boot +##------------------------------------------------------------------------------ +## Helpers for unit and integration test targets +##------------------------------------------------------------------------------ +define KERNEL_TEST_RUNNER + #!/usr/bin/env bash + + TEST_ELF=$$(echo $$1 | sed -e 's/.*target/target/g') + TEST_BINARY=$$(echo $$1.img | sed -e 's/.*target/target/g') + + $(OBJCOPY_CMD) $$TEST_ELF $$TEST_BINARY + $(DOCKER_TEST) $(EXEC_TEST_DISPATCH) $(EXEC_QEMU) $(QEMU_TEST_ARGS) -kernel $$TEST_BINARY +endef + +export KERNEL_TEST_RUNNER + +define test_prepare + @mkdir -p target + @echo "$$KERNEL_TEST_RUNNER" > target/kernel_test_runner.sh + @chmod +x target/kernel_test_runner.sh +endef + +test_unit test_integration: FEATURES += --features test_build + +##------------------------------------------------------------------------------ +## Run unit test(s) +##------------------------------------------------------------------------------ +test_unit: + $(call colorecho, "\nCompiling unit test(s) - $(BSP)") + $(call test_prepare) + RUSTFLAGS="$(RUSTFLAGS_PEDANTIC)" $(TEST_CMD) --lib + +##------------------------------------------------------------------------------ +## Run integration test(s) +##------------------------------------------------------------------------------ +test_integration: + $(call colorecho, "\nCompiling integration test(s) - $(BSP)") + $(call test_prepare) + @RUSTFLAGS="$(RUSTFLAGS_PEDANTIC)" $(TEST_CMD) $(TEST_ARG) + +test: test_boot test_unit test_integration endif diff -uNr 11_exceptions_part1_groundwork/src/_arch/aarch64/cpu.rs 12_integrated_testing/src/_arch/aarch64/cpu.rs --- 11_exceptions_part1_groundwork/src/_arch/aarch64/cpu.rs +++ 12_integrated_testing/src/_arch/aarch64/cpu.rs @@ -26,3 +26,24 @@ asm::wfe() } } + +//-------------------------------------------------------------------------------------------------- +// Testing +//-------------------------------------------------------------------------------------------------- +#[cfg(feature = "test_build")] +use qemu_exit::QEMUExit; + +#[cfg(feature = "test_build")] +const QEMU_EXIT_HANDLE: qemu_exit::AArch64 = qemu_exit::AArch64::new(); + +/// Make the host QEMU binary execute `exit(1)`. +#[cfg(feature = "test_build")] +pub fn qemu_exit_failure() -> ! { + QEMU_EXIT_HANDLE.exit_failure() +} + +/// Make the host QEMU binary execute `exit(0)`. +#[cfg(feature = "test_build")] +pub fn qemu_exit_success() -> ! { + QEMU_EXIT_HANDLE.exit_success() +} diff -uNr 11_exceptions_part1_groundwork/src/_arch/aarch64/exception.rs 12_integrated_testing/src/_arch/aarch64/exception.rs --- 11_exceptions_part1_groundwork/src/_arch/aarch64/exception.rs +++ 12_integrated_testing/src/_arch/aarch64/exception.rs @@ -12,7 +12,7 @@ //! crate::exception::arch_exception use core::{cell::UnsafeCell, fmt}; -use cortex_a::{asm, asm::barrier, registers::*}; +use cortex_a::{asm::barrier, registers::*}; use tock_registers::{ interfaces::{Readable, Writeable}, registers::InMemoryRegister, @@ -90,16 +90,6 @@ #[no_mangle] unsafe extern "C" fn current_elx_synchronous(e: &mut ExceptionContext) { - let far_el1 = FAR_EL1.get(); - - // This catches the demo case for this tutorial. If the fault address happens to be 8 GiB, - // advance the exception link register for one instruction, so that execution can continue. - if far_el1 == 8 * 1024 * 1024 * 1024 { - e.elr_el1 += 4; - - asm::eret() - } - default_exception_handler(e); } diff -uNr 11_exceptions_part1_groundwork/src/_arch/aarch64/memory/mmu/translation_table.rs 12_integrated_testing/src/_arch/aarch64/memory/mmu/translation_table.rs --- 11_exceptions_part1_groundwork/src/_arch/aarch64/memory/mmu/translation_table.rs +++ 12_integrated_testing/src/_arch/aarch64/memory/mmu/translation_table.rs @@ -290,3 +290,31 @@ self.lvl2.phys_start_addr_u64() } } + +//-------------------------------------------------------------------------------------------------- +// Testing +//-------------------------------------------------------------------------------------------------- + +#[cfg(test)] +mod tests { + use super::*; + use test_macros::kernel_test; + + /// Check if the size of `struct TableDescriptor` is as expected. + #[kernel_test] + fn size_of_tabledescriptor_equals_64_bit() { + assert_eq!( + core::mem::size_of::(), + core::mem::size_of::() + ); + } + + /// Check if the size of `struct PageDescriptor` is as expected. + #[kernel_test] + fn size_of_pagedescriptor_equals_64_bit() { + assert_eq!( + core::mem::size_of::(), + core::mem::size_of::() + ); + } +} diff -uNr 11_exceptions_part1_groundwork/src/_arch/aarch64/memory/mmu.rs 12_integrated_testing/src/_arch/aarch64/memory/mmu.rs --- 11_exceptions_part1_groundwork/src/_arch/aarch64/memory/mmu.rs +++ 12_integrated_testing/src/_arch/aarch64/memory/mmu.rs @@ -163,3 +163,33 @@ SCTLR_EL1.matches_all(SCTLR_EL1::M::Enable) } } + +//-------------------------------------------------------------------------------------------------- +// Testing +//-------------------------------------------------------------------------------------------------- + +#[cfg(test)] +mod tests { + use super::*; + use core::{cell::UnsafeCell, ops::Range}; + use test_macros::kernel_test; + + /// Check if KERNEL_TABLES is in .bss. + #[kernel_test] + fn kernel_tables_in_bss() { + extern "Rust" { + static __bss_start: UnsafeCell; + static __bss_end_exclusive: UnsafeCell; + } + + let bss_range = unsafe { + Range { + start: __bss_start.get(), + end: __bss_end_exclusive.get(), + } + }; + let kernel_tables_addr = unsafe { &KERNEL_TABLES as *const _ as usize as *mut u64 }; + + assert!(bss_range.contains(&kernel_tables_addr)); + } +} diff -uNr 11_exceptions_part1_groundwork/src/bsp/raspberrypi/console.rs 12_integrated_testing/src/bsp/raspberrypi/console.rs --- 11_exceptions_part1_groundwork/src/bsp/raspberrypi/console.rs +++ 12_integrated_testing/src/bsp/raspberrypi/console.rs @@ -35,3 +35,14 @@ pub fn console() -> &'static impl console::interface::All { &super::PL011_UART } + +//-------------------------------------------------------------------------------------------------- +// Testing +//-------------------------------------------------------------------------------------------------- + +/// Minimal code needed to bring up the console in QEMU (for testing only). This is often less steps +/// than on real hardware due to QEMU's abstractions. +/// +/// For the RPi, nothing needs to be done. +#[cfg(feature = "test_build")] +pub fn qemu_bring_up_console() {} diff -uNr 11_exceptions_part1_groundwork/src/bsp/raspberrypi/memory/mmu.rs 12_integrated_testing/src/bsp/raspberrypi/memory/mmu.rs --- 11_exceptions_part1_groundwork/src/bsp/raspberrypi/memory/mmu.rs +++ 12_integrated_testing/src/bsp/raspberrypi/memory/mmu.rs @@ -69,3 +69,46 @@ pub fn virt_mem_layout() -> &'static KernelVirtualLayout { &LAYOUT } + +//-------------------------------------------------------------------------------------------------- +// Testing +//-------------------------------------------------------------------------------------------------- + +#[cfg(test)] +mod tests { + use super::*; + use test_macros::kernel_test; + + /// Check alignment of the kernel's virtual memory layout sections. + #[kernel_test] + fn virt_mem_layout_sections_are_64KiB_aligned() { + const SIXTYFOUR_KIB: usize = 65536; + + for i in LAYOUT.inner().iter() { + let start: usize = *(i.virtual_range)().start(); + let end: usize = *(i.virtual_range)().end() + 1; + + assert_eq!(start modulo SIXTYFOUR_KIB, 0); + assert_eq!(end modulo SIXTYFOUR_KIB, 0); + assert!(end >= start); + } + } + + /// Ensure the kernel's virtual memory layout is free of overlaps. + #[kernel_test] + fn virt_mem_layout_has_no_overlaps() { + let layout = virt_mem_layout().inner(); + + for (i, first) in layout.iter().enumerate() { + for second in layout.iter().skip(i + 1) { + let first_range = first.virtual_range; + let second_range = second.virtual_range; + + assert!(!first_range().contains(second_range().start())); + assert!(!first_range().contains(second_range().end())); + assert!(!second_range().contains(first_range().start())); + assert!(!second_range().contains(first_range().end())); + } + } + } +} diff -uNr 11_exceptions_part1_groundwork/src/cpu.rs 12_integrated_testing/src/cpu.rs --- 11_exceptions_part1_groundwork/src/cpu.rs +++ 12_integrated_testing/src/cpu.rs @@ -14,3 +14,6 @@ // Architectural Public Reexports //-------------------------------------------------------------------------------------------------- pub use arch_cpu::{nop, wait_forever}; + +#[cfg(feature = "test_build")] +pub use arch_cpu::{qemu_exit_failure, qemu_exit_success}; diff -uNr 11_exceptions_part1_groundwork/src/exception.rs 12_integrated_testing/src/exception.rs --- 11_exceptions_part1_groundwork/src/exception.rs +++ 12_integrated_testing/src/exception.rs @@ -28,3 +28,21 @@ Hypervisor, Unknown, } + +//-------------------------------------------------------------------------------------------------- +// Testing +//-------------------------------------------------------------------------------------------------- + +#[cfg(test)] +mod tests { + use super::*; + use test_macros::kernel_test; + + /// Libkernel unit tests must execute in kernel mode. + #[kernel_test] + fn test_runner_executes_in_kernel_mode() { + let (level, _) = current_privilege_level(); + + assert!(level == PrivilegeLevel::Kernel) + } +} diff -uNr 11_exceptions_part1_groundwork/src/lib.rs 12_integrated_testing/src/lib.rs --- 11_exceptions_part1_groundwork/src/lib.rs +++ 12_integrated_testing/src/lib.rs @@ -0,0 +1,187 @@ +// SPDX-License-Identifier: MIT OR Apache-2.0 +// +// Copyright (c) 2018-2021 Andre Richter + +// Rust embedded logo for `make doc`. +#![doc(html_logo_url = "https://git.io/JeGIp")] + +//! The `kernel` library. +//! +//! Used to compose the final kernel binary. +//! +//! # Code organization and architecture +//! +//! The code is divided into different *modules*, each representing a typical **subsystem** of the +//! `kernel`. Top-level module files of subsystems reside directly in the `src` folder. For example, +//! `src/memory.rs` contains code that is concerned with all things memory management. +//! +//! ## Visibility of processor architecture code +//! +//! Some of the `kernel`'s subsystems depend on low-level code that is specific to the target +//! processor architecture. For each supported processor architecture, there exists a subfolder in +//! `src/_arch`, for example, `src/_arch/aarch64`. +//! +//! The architecture folders mirror the subsystem modules laid out in `src`. For example, +//! architectural code that belongs to the `kernel`'s MMU subsystem (`src/memory/mmu.rs`) would go +//! into `src/_arch/aarch64/memory/mmu.rs`. The latter file is loaded as a module in +//! `src/memory/mmu.rs` using the `path attribute`. Usually, the chosen module name is the generic +//! module's name prefixed with `arch_`. +//! +//! For example, this is the top of `src/memory/mmu.rs`: +//! +//! ``` +//! #[cfg(target_arch = "aarch64")] +//! #[path = "../_arch/aarch64/memory/mmu.rs"] +//! mod arch_mmu; +//! ``` +//! +//! Often times, items from the `arch_ module` will be publicly reexported by the parent module. +//! This way, each architecture specific module can provide its implementation of an item, while the +//! caller must not be concerned which architecture has been conditionally compiled. +//! +//! ## BSP code +//! +//! `BSP` stands for Board Support Package. `BSP` code is organized under `src/bsp.rs` and contains +//! target board specific definitions and functions. These are things such as the board's memory map +//! or instances of drivers for devices that are featured on the respective board. +//! +//! Just like processor architecture code, the `BSP` code's module structure tries to mirror the +//! `kernel`'s subsystem modules, but there is no reexporting this time. That means whatever is +//! provided must be called starting from the `bsp` namespace, e.g. `bsp::driver::driver_manager()`. +//! +//! ## Kernel interfaces +//! +//! Both `arch` and `bsp` contain code that is conditionally compiled depending on the actual target +//! and board for which the kernel is compiled. For example, the `interrupt controller` hardware of +//! the `Raspberry Pi 3` and the `Raspberry Pi 4` is different, but we want the rest of the `kernel` +//! code to play nicely with any of the two without much hassle. +//! +//! In order to provide a clean abstraction between `arch`, `bsp` and `generic kernel code`, +//! `interface` traits are provided *whenever possible* and *where it makes sense*. They are defined +//! in the respective subsystem module and help to enforce the idiom of *program to an interface, +//! not an implementation*. For example, there will be a common IRQ handling interface which the two +//! different interrupt controller `drivers` of both Raspberrys will implement, and only export the +//! interface to the rest of the `kernel`. +//! +//! ``` +//! +-------------------+ +//! | Interface (Trait) | +//! | | +//! +--+-------------+--+ +//! ^ ^ +//! | | +//! | | +//! +----------+--+ +--+----------+ +//! | kernel code | | bsp code | +//! | | | arch code | +//! +-------------+ +-------------+ +//! ``` +//! +//! # Summary +//! +//! For a logical `kernel` subsystem, corresponding code can be distributed over several physical +//! locations. Here is an example for the **memory** subsystem: +//! +//! - `src/memory.rs` and `src/memory/**/*` +//! - Common code that is agnostic of target processor architecture and `BSP` characteristics. +//! - Example: A function to zero a chunk of memory. +//! - Interfaces for the memory subsystem that are implemented by `arch` or `BSP` code. +//! - Example: An `MMU` interface that defines `MMU` function prototypes. +//! - `src/bsp/__board_name__/memory.rs` and `src/bsp/__board_name__/memory/**/*` +//! - `BSP` specific code. +//! - Example: The board's memory map (physical addresses of DRAM and MMIO devices). +//! - `src/_arch/__arch_name__/memory.rs` and `src/_arch/__arch_name__/memory/**/*` +//! - Processor architecture specific code. +//! - Example: Implementation of the `MMU` interface for the `__arch_name__` processor +//! architecture. +//! +//! From a namespace perspective, **memory** subsystem code lives in: +//! +//! - `crate::memory::*` +//! - `crate::bsp::memory::*` +//! +//! # Boot flow +//! +//! 1. The kernel's entry point is the function `cpu::boot::arch_boot::_start()`. +//! - It is implemented in `src/_arch/__arch_name__/cpu/boot.s`. +//! 2. Once finished with architectural setup, the arch code calls `kernel_init()`. + +#![allow(clippy::upper_case_acronyms)] +#![allow(incomplete_features)] +#![feature(const_fn_fn_ptr_basics)] +#![feature(const_generics)] +#![feature(const_panic)] +#![feature(core_intrinsics)] +#![feature(format_args_nl)] +#![feature(global_asm)] +#![feature(linkage)] +#![feature(panic_info_message)] +#![feature(trait_alias)] +#![no_std] +// Testing +#![cfg_attr(test, no_main)] +#![feature(custom_test_frameworks)] +#![reexport_test_harness_main = "test_main"] +#![test_runner(crate::test_runner)] + +mod panic_wait; +mod synchronization; + +pub mod bsp; +pub mod console; +pub mod cpu; +pub mod driver; +pub mod exception; +pub mod memory; +pub mod print; +pub mod time; + +//-------------------------------------------------------------------------------------------------- +// Public Code +//-------------------------------------------------------------------------------------------------- + +/// Version string. +pub fn version() -> &'static str { + concat!( + env!("CARGO_PKG_NAME"), + " version ", + env!("CARGO_PKG_VERSION") + ) +} + +#[cfg(not(test))] +extern "Rust" { + fn kernel_init() -> !; +} + +//-------------------------------------------------------------------------------------------------- +// Testing +//-------------------------------------------------------------------------------------------------- + +/// The default runner for unit tests. +pub fn test_runner(tests: &[&test_types::UnitTest]) { + // This line will be printed as the test header. + println!("Running {} tests", tests.len()); + + for (i, test) in tests.iter().enumerate() { + print!("{:>3}. {:.<58}", i + 1, test.name); + + // Run the actual test. + (test.test_func)(); + + // Failed tests call panic!(). Execution reaches here only if the test has passed. + println!("[ok]") + } +} + +/// The `kernel_init()` for unit tests. +#[cfg(test)] +#[no_mangle] +unsafe fn kernel_init() -> ! { + exception::handling_init(); + bsp::console::qemu_bring_up_console(); + + test_main(); + + cpu::qemu_exit_success() +} diff -uNr 11_exceptions_part1_groundwork/src/main.rs 12_integrated_testing/src/main.rs --- 11_exceptions_part1_groundwork/src/main.rs +++ 12_integrated_testing/src/main.rs @@ -6,127 +6,12 @@ #![doc(html_logo_url = "https://git.io/JeGIp")] //! The `kernel` binary. -//! -//! # Code organization and architecture -//! -//! The code is divided into different *modules*, each representing a typical **subsystem** of the -//! `kernel`. Top-level module files of subsystems reside directly in the `src` folder. For example, -//! `src/memory.rs` contains code that is concerned with all things memory management. -//! -//! ## Visibility of processor architecture code -//! -//! Some of the `kernel`'s subsystems depend on low-level code that is specific to the target -//! processor architecture. For each supported processor architecture, there exists a subfolder in -//! `src/_arch`, for example, `src/_arch/aarch64`. -//! -//! The architecture folders mirror the subsystem modules laid out in `src`. For example, -//! architectural code that belongs to the `kernel`'s MMU subsystem (`src/memory/mmu.rs`) would go -//! into `src/_arch/aarch64/memory/mmu.rs`. The latter file is loaded as a module in -//! `src/memory/mmu.rs` using the `path attribute`. Usually, the chosen module name is the generic -//! module's name prefixed with `arch_`. -//! -//! For example, this is the top of `src/memory/mmu.rs`: -//! -//! ``` -//! #[cfg(target_arch = "aarch64")] -//! #[path = "../_arch/aarch64/memory/mmu.rs"] -//! mod arch_mmu; -//! ``` -//! -//! Often times, items from the `arch_ module` will be publicly reexported by the parent module. -//! This way, each architecture specific module can provide its implementation of an item, while the -//! caller must not be concerned which architecture has been conditionally compiled. -//! -//! ## BSP code -//! -//! `BSP` stands for Board Support Package. `BSP` code is organized under `src/bsp.rs` and contains -//! target board specific definitions and functions. These are things such as the board's memory map -//! or instances of drivers for devices that are featured on the respective board. -//! -//! Just like processor architecture code, the `BSP` code's module structure tries to mirror the -//! `kernel`'s subsystem modules, but there is no reexporting this time. That means whatever is -//! provided must be called starting from the `bsp` namespace, e.g. `bsp::driver::driver_manager()`. -//! -//! ## Kernel interfaces -//! -//! Both `arch` and `bsp` contain code that is conditionally compiled depending on the actual target -//! and board for which the kernel is compiled. For example, the `interrupt controller` hardware of -//! the `Raspberry Pi 3` and the `Raspberry Pi 4` is different, but we want the rest of the `kernel` -//! code to play nicely with any of the two without much hassle. -//! -//! In order to provide a clean abstraction between `arch`, `bsp` and `generic kernel code`, -//! `interface` traits are provided *whenever possible* and *where it makes sense*. They are defined -//! in the respective subsystem module and help to enforce the idiom of *program to an interface, -//! not an implementation*. For example, there will be a common IRQ handling interface which the two -//! different interrupt controller `drivers` of both Raspberrys will implement, and only export the -//! interface to the rest of the `kernel`. -//! -//! ``` -//! +-------------------+ -//! | Interface (Trait) | -//! | | -//! +--+-------------+--+ -//! ^ ^ -//! | | -//! | | -//! +----------+--+ +--+----------+ -//! | kernel code | | bsp code | -//! | | | arch code | -//! +-------------+ +-------------+ -//! ``` -//! -//! # Summary -//! -//! For a logical `kernel` subsystem, corresponding code can be distributed over several physical -//! locations. Here is an example for the **memory** subsystem: -//! -//! - `src/memory.rs` and `src/memory/**/*` -//! - Common code that is agnostic of target processor architecture and `BSP` characteristics. -//! - Example: A function to zero a chunk of memory. -//! - Interfaces for the memory subsystem that are implemented by `arch` or `BSP` code. -//! - Example: An `MMU` interface that defines `MMU` function prototypes. -//! - `src/bsp/__board_name__/memory.rs` and `src/bsp/__board_name__/memory/**/*` -//! - `BSP` specific code. -//! - Example: The board's memory map (physical addresses of DRAM and MMIO devices). -//! - `src/_arch/__arch_name__/memory.rs` and `src/_arch/__arch_name__/memory/**/*` -//! - Processor architecture specific code. -//! - Example: Implementation of the `MMU` interface for the `__arch_name__` processor -//! architecture. -//! -//! From a namespace perspective, **memory** subsystem code lives in: -//! -//! - `crate::memory::*` -//! - `crate::bsp::memory::*` -//! -//! # Boot flow -//! -//! 1. The kernel's entry point is the function `cpu::boot::arch_boot::_start()`. -//! - It is implemented in `src/_arch/__arch_name__/cpu/boot.s`. -//! 2. Once finished with architectural setup, the arch code calls `kernel_init()`. - -#![allow(clippy::upper_case_acronyms)] -#![allow(incomplete_features)] -#![feature(const_fn_fn_ptr_basics)] -#![feature(const_generics)] -#![feature(const_panic)] -#![feature(core_intrinsics)] + #![feature(format_args_nl)] -#![feature(global_asm)] -#![feature(panic_info_message)] -#![feature(trait_alias)] #![no_main] #![no_std] -mod bsp; -mod console; -mod cpu; -mod driver; -mod exception; -mod memory; -mod panic_wait; -mod print; -mod synchronization; -mod time; +use libkernel::{bsp, console, driver, exception, info, memory, time}; /// Early init code. /// @@ -137,6 +22,7 @@ /// - MMU + Data caching must be activated at the earliest. Without it, any atomic operations, /// e.g. the yet-to-be-introduced spinlocks in the device drivers (which currently employ /// NullLocks instead of spinlocks), will fail to work (properly) on the RPi SoCs. +#[no_mangle] unsafe fn kernel_init() -> ! { use driver::interface::DriverManager; use memory::mmu::interface::MMU; @@ -163,15 +49,9 @@ fn kernel_main() -> ! { use bsp::console::console; use console::interface::All; - use core::time::Duration; use driver::interface::DriverManager; - use time::interface::TimeManager; - info!( - "{} version {}", - env!("CARGO_PKG_NAME"), - env!("CARGO_PKG_VERSION") - ); + info!("{}", libkernel::version()); info!("Booting on: {}", bsp::board_name()); info!("MMU online. Special regions:"); @@ -197,31 +77,6 @@ info!(" {}. {}", i + 1, driver.compatible()); } - info!("Timer test, spinning for 1 second"); - time::time_manager().spin_for(Duration::from_secs(1)); - - // Cause an exception by accessing a virtual address for which no translation was set up. This - // code accesses the address 8 GiB, which is outside the mapped address space. - // - // For demo purposes, the exception handler will catch the faulting 8 GiB address and allow - // execution to continue. - info!(""); - info!("Trying to read from address 8 GiB..."); - let mut big_addr: u64 = 8 * 1024 * 1024 * 1024; - unsafe { core::ptr::read_volatile(big_addr as *mut u64) }; - - info!("************************************************"); - info!("Whoa! We recovered from a synchronous exception!"); - info!("************************************************"); - info!(""); - info!("Let's try again"); - - // Now use address 9 GiB. The exception handler won't forgive us this time. - info!("Trying to read from address 9 GiB..."); - big_addr = 9 * 1024 * 1024 * 1024; - unsafe { core::ptr::read_volatile(big_addr as *mut u64) }; - - // Will never reach here in this tutorial. info!("Echoing input now"); // Discard any spurious received characters before going into echo mode. diff -uNr 11_exceptions_part1_groundwork/src/memory/mmu.rs 12_integrated_testing/src/memory/mmu.rs --- 11_exceptions_part1_groundwork/src/memory/mmu.rs +++ 12_integrated_testing/src/memory/mmu.rs @@ -66,7 +66,6 @@ /// Architecture agnostic translation types. #[allow(missing_docs)] -#[allow(dead_code)] #[derive(Copy, Clone)] pub enum Translation { Identity, @@ -261,4 +260,9 @@ info!("{}", i); } } + + #[cfg(test)] + pub fn inner(&self) -> &[TranslationDescriptor; NUM_SPECIAL_RANGES] { + &self.inner + } } diff -uNr 11_exceptions_part1_groundwork/src/panic_wait.rs 12_integrated_testing/src/panic_wait.rs --- 11_exceptions_part1_groundwork/src/panic_wait.rs +++ 12_integrated_testing/src/panic_wait.rs @@ -17,6 +17,23 @@ unsafe { bsp::console::panic_console_out().write_fmt(args).unwrap() }; } +/// The point of exit for `libkernel`. +/// +/// It is linked weakly, so that the integration tests can overload its standard behavior. +#[linkage = "weak"] +#[no_mangle] +fn _panic_exit() -> ! { + #[cfg(not(feature = "test_build"))] + { + cpu::wait_forever() + } + + #[cfg(feature = "test_build")] + { + cpu::qemu_exit_failure() + } +} + /// Prints with a newline - only use from the panic handler. /// /// Carbon copy from @@ -35,5 +52,5 @@ panic_println!("\nKernel panic!"); } - cpu::wait_forever() + _panic_exit() } diff -uNr 11_exceptions_part1_groundwork/test-macros/Cargo.toml 12_integrated_testing/test-macros/Cargo.toml --- 11_exceptions_part1_groundwork/test-macros/Cargo.toml +++ 12_integrated_testing/test-macros/Cargo.toml @@ -0,0 +1,14 @@ +[package] +name = "test-macros" +version = "0.1.0" +authors = ["Andre Richter "] +edition = "2018" + +[lib] +proc-macro = true + +[dependencies] +proc-macro2 = "1.x" +quote = "1.x" +syn = { version = "1.x", features = ["full"] } +test-types = { path = "../test-types" } diff -uNr 11_exceptions_part1_groundwork/test-macros/src/lib.rs 12_integrated_testing/test-macros/src/lib.rs --- 11_exceptions_part1_groundwork/test-macros/src/lib.rs +++ 12_integrated_testing/test-macros/src/lib.rs @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: MIT OR Apache-2.0 +// +// Copyright (c) 2019-2021 Andre Richter + +use proc_macro::TokenStream; +use proc_macro2::Span; +use quote::quote; +use syn::{parse_macro_input, Ident, ItemFn}; + +#[proc_macro_attribute] +pub fn kernel_test(_attr: TokenStream, input: TokenStream) -> TokenStream { + let f = parse_macro_input!(input as ItemFn); + + let test_name = &format!("{}", f.sig.ident.to_string()); + let test_ident = Ident::new( + &format!("{}_TEST_CONTAINER", f.sig.ident.to_string().to_uppercase()), + Span::call_site(), + ); + let test_code_block = f.block; + + quote!( + #[test_case] + const #test_ident: test_types::UnitTest = test_types::UnitTest { + name: #test_name, + test_func: || #test_code_block, + }; + ) + .into() +} diff -uNr 11_exceptions_part1_groundwork/tests/00_console_sanity.rb 12_integrated_testing/tests/00_console_sanity.rb --- 11_exceptions_part1_groundwork/tests/00_console_sanity.rb +++ 12_integrated_testing/tests/00_console_sanity.rb @@ -0,0 +1,57 @@ +# frozen_string_literal: true + +# SPDX-License-Identifier: MIT OR Apache-2.0 +# +# Copyright (c) 2019-2021 Andre Richter + +require 'expect' + +TIMEOUT_SECS = 3 + +# Error class for when expect times out. +class ExpectTimeoutError < StandardError + def initialize + super('Timeout while expecting string') + end +end + +# Verify sending and receiving works as expected. +class TxRxHandshake + def name + 'Transmit and Receive handshake' + end + + def run(qemu_out, qemu_in) + qemu_in.write_nonblock('ABC') + raise ExpectTimeoutError if qemu_out.expect('OK1234', TIMEOUT_SECS).nil? + end +end + +# Check for correct TX statistics implementation. Depends on test 1 being run first. +class TxStatistics + def name + 'Transmit statistics' + end + + def run(qemu_out, _qemu_in) + raise ExpectTimeoutError if qemu_out.expect('6', TIMEOUT_SECS).nil? + end +end + +# Check for correct RX statistics implementation. Depends on test 1 being run first. +class RxStatistics + def name + 'Receive statistics' + end + + def run(qemu_out, _qemu_in) + raise ExpectTimeoutError if qemu_out.expect('3', TIMEOUT_SECS).nil? + end +end + +##-------------------------------------------------------------------------------------------------- +## Test registration +##-------------------------------------------------------------------------------------------------- +def subtest_collection + [TxRxHandshake.new, TxStatistics.new, RxStatistics.new] +end diff -uNr 11_exceptions_part1_groundwork/tests/00_console_sanity.rs 12_integrated_testing/tests/00_console_sanity.rs --- 11_exceptions_part1_groundwork/tests/00_console_sanity.rs +++ 12_integrated_testing/tests/00_console_sanity.rs @@ -0,0 +1,35 @@ +// SPDX-License-Identifier: MIT OR Apache-2.0 +// +// Copyright (c) 2019-2021 Andre Richter + +//! Console sanity tests - RX, TX and statistics. + +#![feature(format_args_nl)] +#![no_main] +#![no_std] + +use libkernel::{bsp, console, cpu, exception, print}; + +#[no_mangle] +unsafe fn kernel_init() -> ! { + use bsp::console::console; + use console::interface::*; + + exception::handling_init(); + bsp::console::qemu_bring_up_console(); + + // Handshake + assert_eq!(console().read_char(), 'A'); + assert_eq!(console().read_char(), 'B'); + assert_eq!(console().read_char(), 'C'); + print!("OK1234"); + + // 6 + print!("{}", console().chars_written()); + + // 3 + print!("{}", console().chars_read()); + + // The QEMU process running this test will be closed by the I/O test harness. + cpu::wait_forever(); +} diff -uNr 11_exceptions_part1_groundwork/tests/01_timer_sanity.rs 12_integrated_testing/tests/01_timer_sanity.rs --- 11_exceptions_part1_groundwork/tests/01_timer_sanity.rs +++ 12_integrated_testing/tests/01_timer_sanity.rs @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: MIT OR Apache-2.0 +// +// Copyright (c) 2019-2021 Andre Richter + +//! Timer sanity tests. + +#![feature(custom_test_frameworks)] +#![no_main] +#![no_std] +#![reexport_test_harness_main = "test_main"] +#![test_runner(libkernel::test_runner)] + +use core::time::Duration; +use libkernel::{bsp, cpu, exception, time, time::interface::TimeManager}; +use test_macros::kernel_test; + +#[no_mangle] +unsafe fn kernel_init() -> ! { + exception::handling_init(); + bsp::console::qemu_bring_up_console(); + + // Depending on CPU arch, some timer bring-up code could go here. Not needed for the RPi. + + test_main(); + + cpu::qemu_exit_success() +} + +/// Simple check that the timer is running. +#[kernel_test] +fn timer_is_counting() { + assert!(time::time_manager().uptime().as_nanos() > 0) +} + +/// Timer resolution must be sufficient. +#[kernel_test] +fn timer_resolution_is_sufficient() { + assert!(time::time_manager().resolution().as_nanos() < 100) +} + +/// Sanity check spin_for() implementation. +#[kernel_test] +fn spin_accuracy_check_1_second() { + let t1 = time::time_manager().uptime(); + time::time_manager().spin_for(Duration::from_secs(1)); + let t2 = time::time_manager().uptime(); + + assert_eq!((t2 - t1).as_secs(), 1) +} diff -uNr 11_exceptions_part1_groundwork/tests/02_exception_sync_page_fault.rs 12_integrated_testing/tests/02_exception_sync_page_fault.rs --- 11_exceptions_part1_groundwork/tests/02_exception_sync_page_fault.rs +++ 12_integrated_testing/tests/02_exception_sync_page_fault.rs @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: MIT OR Apache-2.0 +// +// Copyright (c) 2019-2021 Andre Richter + +//! Page faults must result in synchronous exceptions. + +#![feature(format_args_nl)] +#![no_main] +#![no_std] + +/// Overwrites libkernel's `panic_wait::_panic_exit()` so that it returns a "success" code. +/// +/// In this test, teaching the panic is a success, because it is called from the synchronous +/// exception handler, which is what this test wants to achieve. +/// +/// It also means that this integration test can not use any other code that calls panic!() directly +/// or indirectly. +mod panic_exit_success; + +use libkernel::{bsp, cpu, exception, memory, println}; + +#[no_mangle] +unsafe fn kernel_init() -> ! { + use memory::mmu::interface::MMU; + + exception::handling_init(); + bsp::console::qemu_bring_up_console(); + + // This line will be printed as the test header. + println!("Testing synchronous exception handling by causing a page fault"); + + if let Err(string) = memory::mmu::mmu().enable_mmu_and_caching() { + println!("MMU: {}", string); + cpu::qemu_exit_failure() + } + + println!("Writing beyond mapped area to address 9 GiB..."); + let big_addr: u64 = 9 * 1024 * 1024 * 1024; + core::ptr::read_volatile(big_addr as *mut u64); + + // If execution reaches here, the memory access above did not cause a page fault exception. + cpu::qemu_exit_failure() +} diff -uNr 11_exceptions_part1_groundwork/tests/boot_test_string.rb 12_integrated_testing/tests/boot_test_string.rb --- 11_exceptions_part1_groundwork/tests/boot_test_string.rb +++ 12_integrated_testing/tests/boot_test_string.rb @@ -1,3 +1,3 @@ # frozen_string_literal: true -EXPECTED_PRINT = 'lr : 0x' +EXPECTED_PRINT = 'Echoing input now' diff -uNr 11_exceptions_part1_groundwork/tests/panic_exit_success/mod.rs 12_integrated_testing/tests/panic_exit_success/mod.rs --- 11_exceptions_part1_groundwork/tests/panic_exit_success/mod.rs +++ 12_integrated_testing/tests/panic_exit_success/mod.rs @@ -0,0 +1,9 @@ +// SPDX-License-Identifier: MIT OR Apache-2.0 +// +// Copyright (c) 2019-2021 Andre Richter + +/// Overwrites libkernel's `panic_wait::_panic_exit()` with the QEMU-exit version. +#[no_mangle] +fn _panic_exit() -> ! { + libkernel::cpu::qemu_exit_success() +} diff -uNr 11_exceptions_part1_groundwork/test-types/Cargo.toml 12_integrated_testing/test-types/Cargo.toml --- 11_exceptions_part1_groundwork/test-types/Cargo.toml +++ 12_integrated_testing/test-types/Cargo.toml @@ -0,0 +1,5 @@ +[package] +name = "test-types" +version = "0.1.0" +authors = ["Andre Richter "] +edition = "2018" diff -uNr 11_exceptions_part1_groundwork/test-types/src/lib.rs 12_integrated_testing/test-types/src/lib.rs --- 11_exceptions_part1_groundwork/test-types/src/lib.rs +++ 12_integrated_testing/test-types/src/lib.rs @@ -0,0 +1,16 @@ +// SPDX-License-Identifier: MIT OR Apache-2.0 +// +// Copyright (c) 2019-2021 Andre Richter + +//! Types for the `custom_test_frameworks` implementation. + +#![no_std] + +/// Unit test container. +pub struct UnitTest { + /// Name of the test. + pub name: &'static str, + + /// Function pointer to the test. + pub test_func: fn(), +} ```