kernel/tools/testing/selftests/nolibc, branch linux-6.2.y

selftests/nolibc: Always rebuild the sysroot when running a test

2022-10-28T22:17:22Z

Paul and I got trapped a few times by not seeing the effects of applying a patch to the nolibc source code until a "make clean" was issued in the nolibc directory. It's particularly annoying when trying to confirm that a proposed patch really solves a problem (or that reverting it reintroduces the problem). The reason for the sysroot not being rebuilt was that it can be quite slow. But in fact it's only slow after a "make clean" issued at the kernel's topdir, because it's the main "make headers" that can take a tens of seconds; as long as "usr/include" still contains headers, the "headers_install" phase is only a quick "rsync", and rebuilding the whole nolibc sysroot takes a bit less than one second, which is perfectly acceptable for a test, even more once the time lost caused by misleading results is factored in. This patch marks the sysroot target as phony and starts by clearing the previous sysroot for the current architecture before reinstalling it. Thanks to this, applying a patch to nolibc makes the effect immediately visible to "make nolibc-test": $ time make -j -C tools/testing/selftests/nolibc nolibc-test make: Entering directory '/k/tools/testing/selftests/nolibc' MKDIR sysroot/x86/include make[1]: Entering directory '/k/tools/include/nolibc' make[2]: Entering directory '/k' make[2]: Leaving directory '/k' make[2]: Entering directory '/k' INSTALL /k/tools/testing/selftests/nolibc/sysroot/sysroot/include make[2]: Leaving directory '/k' make[1]: Leaving directory '/k/tools/include/nolibc' CC nolibc-test make: Leaving directory '/k/tools/testing/selftests/nolibc' real 0m0.869s user 0m0.716s sys 0m0.149s Cc: "Paul E. McKenney" Link: https://lore.kernel.org/all/20221021155645.GK5600@paulmck-ThinkPad-P17-Gen-1/ Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney

selftests/nolibc: Add 7 tests for memcmp()

2022-10-28T22:17:22Z

This adds 7 combinations of input values for memcmp() using signed and unsigned bytes, which will trigger on the original code before Rasmus' fix. This is mostly aimed at helping backporters verify their work, and showing how tests for corner cases can be added to the selftests suite. Before the fix it reports: 12 memcmp_20_20 = 0 [OK] 13 memcmp_20_60 = -64 [OK] 14 memcmp_60_20 = 64 [OK] 15 memcmp_20_e0 = 64 [FAIL] 16 memcmp_e0_20 = -64 [FAIL] 17 memcmp_80_e0 = -96 [OK] 18 memcmp_e0_80 = 96 [OK] And after: 12 memcmp_20_20 = 0 [OK] 13 memcmp_20_60 = -64 [OK] 14 memcmp_60_20 = 64 [OK] 15 memcmp_20_e0 = -192 [OK] 16 memcmp_e0_20 = 192 [OK] 17 memcmp_80_e0 = -96 [OK] 18 memcmp_e0_80 = 96 [OK] Cc: Rasmus Villemoes Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney

selftests/nolibc: Avoid generated files being committed

2022-08-31T12:17:45Z

After running the nolibc tests, the "git status" is not clean because the generated files are not ignored. Create a `.gitignore` inside the selftests/nolibc directory to ignore them. Cc: Ammar Faizi Cc: Fernanda Ma'rouf Signed-off-by: Fernanda Ma'rouf Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney

selftests/nolibc: add a "help" target

2022-08-31T12:17:45Z

It presents the supported targets, and becomes the default target to save the user from having to read the makefile. The "all" target was placed after it and now points to "run" to do everything since it's no longer the default one. Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney

selftests/nolibc: "sysroot" target installs a local copy of the sysroot

2022-08-31T12:17:45Z

It's not convenient to rely on a sysroot built in another directory, especially when running cross-compilation tests, where one has to switch back and forth between directories. Let's make it possible to install the sysroot directly in the test directory. It's not big and even benefits from being copied by arch so that it's easier to switch between archs if needed. The new "sysroot" target does this, it just calls "headers_standalone" from nolibc to install the sysroot right here. Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney

selftests/nolibc: add a "run" target to start the kernel in QEMU

2022-08-31T12:17:45Z

The "run" target will build the kernel and start it in QEMU. The "rerun" target will not have the kernel dependency and will just try to start QEMU. The QEMU architecture used to start the kernel is derived from the configured ARCH. This might need to be improved for archs which include different variants under the same name (mips vs mipsel, +/-64, riscv32 vs riscv64). This could be tested for i386, x86, arm, arm64, mips and riscv (the later two reporting issues on some tests). It is possible to pass a test specification for nolibc-test in the TEST variable, which will be passed as-is as NOLIBC_TEST. On success, the number of successful tests is printed. On failure, failed lines are individually printed. Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney

selftests/nolibc: add a "defconfig" target

2022-08-31T12:17:45Z

While most archs will work fine with "make defconfig", not all will do, and it's not always easy to remember the most suitable choice to use for a specific architecture. This adds a "defconfig" target to the Makefile so that one may easily run "make -C ... defconfig" and make sure to clean and rebuild a fresh config. This is *not* used by default because we want to preserve the user's config by default. Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney

selftests/nolibc: add a "kernel" target to build the kernel with the initramfs

2022-08-31T12:17:45Z

The "kernel" target rebuilds the kernel with the current config for the selected arch, with an initramfs containing the nolibc-test utility. Since image names depend on the architecture, the currently supported ones are referenced and resolved based on the architecture. Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney

selftests/nolibc: support glibc as well

2022-08-31T12:17:44Z

Adding support for glibc can be useful to distinguish between bugs in nolibc and bugs in the kernel when a syscall reports an unusual value. It's not that much work and should not affect the long term maintainability of the tests. The necessary changes can essentially be summed up like this: - set _GNU_SOURCE a the top to access some definitions - many includes added when we know we don't come from nolibc (missing the stdio include guard) - disable gettid() which is not exposed by glibc - disable gettimeofday's support of bad pointers since these crash in glibc - add a simple itoa() for errorname(); strerror() is too verbose (no way to get short messages). strerrorname_np() was added in modern glibc (2.32) to do exactly this but that 's too recent to be usable as the default fallback. - use the standard ioperm() definition. May be we need to implement ioperm() in nolibc if that's useful. Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney

selftests/nolibc: condition some tests on /proc existence

2022-08-31T12:17:44Z

If /proc is not available (program run inside a chroot or without sufficient permissions), it's better to disable the associated tests. Some will be preserved like the ones which check for a failure to create some entries there since they're still supposed to fail. Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney