Make sure the byte order and ABI of the userprogs matches the one of the kernel, similar to how the bit size is handled. Otherwise the userprogs may not be executable. This happens for example on powerpc little endian, or riscv32.

Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de --- Makefile | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile index c4293cf91e968ca8ee64452841fb266e24df63f6..b9aa1058321dabd3b3dd5610e45a2807dfa257f4 100644 --- a/Makefile +++ b/Makefile @@ -1129,8 +1129,8 @@ ifneq ($(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS),) LDFLAGS_vmlinux += --emit-relocs --discard-none endif

-# Align the bit size of userspace programs with the kernel -USERFLAGS_FROM_KERNEL := -m32 -m64 --target=% +# Align the bit size, byte order and architecture of userspace programs with the kernel +USERFLAGS_FROM_KERNEL := -m32 -m64 -mlittle-endian -mbig-endian --target=% -march=% -mabi=% KBUILD_USERCFLAGS += $(filter $(USERFLAGS_FROM_KERNEL), $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)) KBUILD_USERLDFLAGS += $(filter $(USERFLAGS_FROM_KERNEL), $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))

For the kunit UAPI functionality this feature is needed.

This reverts commit d1b99cdf22e0 ("init: remove unused CONFIG_CC_CAN_LINK_STATIC")

Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de --- init/Kconfig | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/init/Kconfig b/init/Kconfig index af4c2f0854554bbcdf193852cf5c1d2c2accc64f..26cafbad4f1560fb56b4bef31ae29baf54175661 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -87,6 +87,11 @@ config CC_CAN_LINK default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag))

+config CC_CAN_LINK_STATIC + bool + default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag) -static) if 64BIT + default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m32-flag) -static) + # Fixed in GCC 14, 13.3, 12.4 and 11.5 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 config GCC_ASM_GOTO_OUTPUT_BROKEN

The KUnit UAPI infrastructure starts userspace processes. As it should be able to be built as a module, export the necessary symbols.

Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de

--- To: Kees Cook kees@kernel.org To: Alexander Viro viro@zeniv.linux.org.uk To: Christian Brauner brauner@kernel.org To: Jan Kara jack@suse.cz Cc: linux-mm@kvack.org Cc: linux-fsdevel@vger.kernel.org

./get_maintainer.pl would have also Cc-ed all of the memory management and scheduler maintainers. I trimmed the list to only BINFMT/EXEC and VFS. --- fs/exec.c | 2 ++ fs/file.c | 1 + fs/filesystems.c | 2 ++ fs/fs_struct.c | 1 + fs/pipe.c | 2 ++ kernel/exit.c | 3 +++ kernel/fork.c | 2 ++ 7 files changed, 13 insertions(+)

diff --git a/fs/exec.c b/fs/exec.c index 1f5fdd2e096e392b342f122d35aba4cf035441c7..13f7f27641942eddcb179bdd93d99b799d155813 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -68,6 +68,7 @@ #include <linux/user_events.h> #include <linux/rseq.h> #include <linux/ksm.h> +#include <linux/export.h>

#include <linux/uaccess.h> #include <asm/mmu_context.h> @@ -1919,6 +1920,7 @@ int kernel_execve(const char *kernel_filename, putname(filename); return retval; } +EXPORT_SYMBOL_GPL_FOR_MODULES(kernel_execve, "kunit-uapi");

static int do_execve(struct filename *filename, const char __user *const __user *__argv, diff --git a/fs/file.c b/fs/file.c index 3a3146664cf37115624e12f7f06826d48827e9d7..89d07feb9c328337451ce40cb0f368b6cb986c2c 100644 --- a/fs/file.c +++ b/fs/file.c @@ -1317,6 +1317,7 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags) spin_unlock(&files->file_lock); return err; } +EXPORT_SYMBOL_GPL_FOR_MODULES(replace_fd, "kunit-uapi");

/** * receive_fd() - Install received file into file descriptor table diff --git a/fs/filesystems.c b/fs/filesystems.c index 95e5256821a53494d88f496193305a2e50e04444..a3a588f387bbd8268246d1026389deaadf265d0b 100644 --- a/fs/filesystems.c +++ b/fs/filesystems.c @@ -17,6 +17,7 @@ #include <linux/slab.h> #include <linux/uaccess.h> #include <linux/fs_parser.h> +#include <linux/export.h>

/* * Handling of filesystem drivers list. @@ -45,6 +46,7 @@ void put_filesystem(struct file_system_type *fs) { module_put(fs->owner); } +EXPORT_SYMBOL_GPL_FOR_MODULES(put_filesystem, "kunit-uapi");

static struct file_system_type **find_filesystem(const char *name, unsigned len) { diff --git a/fs/fs_struct.c b/fs/fs_struct.c index 64c2d0814ed6889cc12603410e6e9dc44089586f..26340d225deba3f2ec30252293fdf417235a6a4a 100644 --- a/fs/fs_struct.c +++ b/fs/fs_struct.c @@ -46,6 +46,7 @@ void set_fs_pwd(struct fs_struct *fs, const struct path *path) if (old_pwd.dentry) path_put(&old_pwd); } +EXPORT_SYMBOL_GPL_FOR_MODULES(set_fs_pwd, "kunit-uapi");

static inline int replace_path(struct path *p, const struct path *old, const struct path *new) { diff --git a/fs/pipe.c b/fs/pipe.c index 45077c37bad154ef146b047834d35d489fcc4d8d..d6cb743d2cfc041f08b498a5a764e9a96dc34069 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -27,6 +27,7 @@ #include <linux/watch_queue.h> #include <linux/sysctl.h> #include <linux/sort.h> +#include <linux/export.h>

#include <linux/uaccess.h> #include <asm/ioctls.h> @@ -971,6 +972,7 @@ int create_pipe_files(struct file **res, int flags) file_set_fsnotify_mode(res[1], FMODE_NONOTIFY_PERM); return 0; } +EXPORT_SYMBOL_GPL_FOR_MODULES(create_pipe_files, "kunit-uapi");

static int __do_pipe_flags(int *fd, struct file **files, int flags) { diff --git a/kernel/exit.c b/kernel/exit.c index bd743900354ca5fc6c550f80e30393a632eb9a4e..610dffb1276ac60b475708587ca053f315fea9c3 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -70,6 +70,7 @@ #include <linux/user_events.h> #include <linux/uaccess.h> #include <linux/pidfs.h> +#include <linux/export.h>

#include <uapi/linux/wait.h>

@@ -1005,6 +1006,7 @@ void __noreturn do_exit(long code) lockdep_free_task(tsk); do_task_dead(); } +EXPORT_SYMBOL_GPL_FOR_MODULES(do_exit, "kunit-uapi");

void __noreturn make_task_dead(int signr) { @@ -1887,6 +1889,7 @@ int kernel_wait(pid_t pid, int *stat) put_pid(wo.wo_pid); return ret; } +EXPORT_SYMBOL_GPL_FOR_MODULES(kernel_wait, "kunit-uapi");

SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, int, options, struct rusage __user *, ru) diff --git a/kernel/fork.c b/kernel/fork.c index 1ee8eb11f38bae1d2eb6de9494aea94b7a19e6c3..5de7a9bc005ade6dcfbdfe1a63cadbef8782658c 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -105,6 +105,7 @@ #include <uapi/linux/pidfd.h> #include <linux/pidfs.h> #include <linux/tick.h> +#include <linux/export.h>

#include <asm/pgalloc.h> #include <linux/uaccess.h> @@ -2676,6 +2677,7 @@ pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags)

return kernel_clone(&args); } +EXPORT_SYMBOL_GPL_FOR_MODULES(user_mode_thread, "kunit-uapi");

#ifdef __ARCH_WANT_SYS_FORK SYSCALL_DEFINE0(fork)

If a subtest itself reports success, but the outer testcase fails, the whole testcase should be reported as a failure. However the status is recalculated based on the test counts, overwriting the outer test result. Synthesize a failed test in this case to make sure the failure is not swallowed.

Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de Reviewed-by: David Gow davidgow@google.com --- tools/testing/kunit/kunit_parser.py | 5 +++++ tools/testing/kunit/kunit_tool_test.py | 3 ++- tools/testing/kunit/test_data/test_is_test_passed-failure-nested.log | 3 +++ 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/tools/testing/kunit/kunit_parser.py b/tools/testing/kunit/kunit_parser.py index c176487356e6c94882046b19ea696d750905b8d5..2478beb28fc3db825855ad46200340e884da7df1 100644 --- a/tools/testing/kunit/kunit_parser.py +++ b/tools/testing/kunit/kunit_parser.py @@ -686,6 +686,11 @@ def bubble_up_test_results(test: Test) -> None: counts.add_status(status) elif test.counts.get_status() == TestStatus.TEST_CRASHED: test.status = TestStatus.TEST_CRASHED + if not test.ok_status(): + for t in subtests: + if not t.ok_status(): + counts.add_status(t.status) + break

def parse_test(lines: LineStream, expected_num: int, log: List[str], is_subtest: bool, printer: Printer) -> Test: """ diff --git a/tools/testing/kunit/kunit_tool_test.py b/tools/testing/kunit/kunit_tool_test.py index b74dc05fc2fe5b3ff629172fc7aafeb5c3d29fb3..48a0dd0f9c87caf9f018aade161db90a613fc407 100755 --- a/tools/testing/kunit/kunit_tool_test.py +++ b/tools/testing/kunit/kunit_tool_test.py @@ -170,8 +170,9 @@ class KUnitParserTest(unittest.TestCase): with open(nested_log) as file: result = kunit_parser.parse_run_tests(file.readlines(), stdout) self.assertEqual(kunit_parser.TestStatus.FAILURE, result.status) - self.assertEqual(result.counts.failed, 2) + self.assertEqual(result.counts.failed, 3) self.assertEqual(kunit_parser.TestStatus.FAILURE, result.subtests[0].status) + self.assertEqual(kunit_parser.TestStatus.SUCCESS, result.subtests[0].subtests[0].status) self.assertEqual(kunit_parser.TestStatus.FAILURE, result.subtests[1].status) self.assertEqual(kunit_parser.TestStatus.FAILURE, result.subtests[1].subtests[0].status)

diff --git a/tools/testing/kunit/test_data/test_is_test_passed-failure-nested.log b/tools/testing/kunit/test_data/test_is_test_passed-failure-nested.log index 2e528da39ab5b2be0fca6cf9160c10929fba3c9e..5498dfd0b0db24663e1a1e9bf78c587de6746522 100644 --- a/tools/testing/kunit/test_data/test_is_test_passed-failure-nested.log +++ b/tools/testing/kunit/test_data/test_is_test_passed-failure-nested.log @@ -1,5 +1,8 @@ KTAP version 1 1..2 + KTAP version 1 + 1..1 + ok 1 test 1 not ok 1 subtest 1 KTAP version 1 1..1

An upcoming change will add 'userprogs' to the kunit subdirectory. For kbuild to properly clean up these build artifacts the subdirectory needs to be always processed.

Pushing the special logic for hook.o into the kunit Makefile also makes the logic easier to understand.

Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de Reviewed-by: David Gow davidgow@google.com --- lib/Makefile | 4 ---- lib/kunit/Makefile | 2 +- 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/lib/Makefile b/lib/Makefile index c38582f187dd81916113319072e5cfef26f26c84..698566135091cc3bf0054f1954b434dc3325364a 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -108,11 +108,7 @@ test_fpu-y := test_fpu_glue.o test_fpu_impl.o CFLAGS_test_fpu_impl.o += $(CC_FLAGS_FPU) CFLAGS_REMOVE_test_fpu_impl.o += $(CC_FLAGS_NO_FPU)

-# Some KUnit files (hooks.o) need to be built-in even when KUnit is a module, -# so we can't just use obj-$(CONFIG_KUNIT). -ifdef CONFIG_KUNIT obj-y += kunit/ -endif

ifeq ($(CONFIG_DEBUG_KOBJECT),y) CFLAGS_kobject.o += -DDEBUG diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile index 5aa51978e456ab3bb60c12071a26cf2bdcb1b508..656f1fa35abcc635e67d5b4cb1bc586b48415ac5 100644 --- a/lib/kunit/Makefile +++ b/lib/kunit/Makefile @@ -17,7 +17,7 @@ kunit-objs += debugfs.o endif

# KUnit 'hooks' are built-in even when KUnit is built as a module. -obj-y += hooks.o +obj-$(if $(CONFIG_KUNIT),y) += hooks.o

obj-$(CONFIG_KUNIT_TEST) += kunit-test.o obj-$(CONFIG_KUNIT_TEST) += platform-test.o

Enable running UAPI tests as part of kunit. The selftests are embedded into the kernel image and their output is forwarded to kunit for unified reporting.

The implementation reuses parts of usermode drivers and usermode helpers. However these frameworks are not used directly as they make it impossible to retrieve a thread's exit code.

Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de

--- To: Kees Cook kees@kernel.org To: Alexander Viro viro@zeniv.linux.org.uk To: Christian Brauner brauner@kernel.org To: Jan Kara jack@suse.cz Cc: linux-mm@kvack.org Cc: linux-fsdevel@vger.kernel.org --- Documentation/dev-tools/kunit/api/index.rst | 5 + Documentation/dev-tools/kunit/api/uapi.rst | 14 ++ MAINTAINERS | 6 + include/kunit/uapi.h | 77 +++++++ lib/kunit/Kconfig | 14 ++ lib/kunit/Makefile | 2 + lib/kunit/kunit-uapi.c | 300 ++++++++++++++++++++++++++++ 7 files changed, 418 insertions(+)

diff --git a/Documentation/dev-tools/kunit/api/index.rst b/Documentation/dev-tools/kunit/api/index.rst index 5cdb552a0808f25baeff5e47a9227b7b62c69e40..34d8fee9a97059d6da919a6fb1a7e359b5e0beef 100644 --- a/Documentation/dev-tools/kunit/api/index.rst +++ b/Documentation/dev-tools/kunit/api/index.rst @@ -9,6 +9,7 @@ API Reference test resource functionredirection + uapi clk of platformdevice @@ -32,6 +33,10 @@ Documentation/dev-tools/kunit/api/functionredirection.rst

- Documents the KUnit Function Redirection API

+Documentation/dev-tools/kunit/api/uapi.rst + + - Documents the KUnit Userspace testing API + Driver KUnit API ================

diff --git a/Documentation/dev-tools/kunit/api/uapi.rst b/Documentation/dev-tools/kunit/api/uapi.rst new file mode 100644 index 0000000000000000000000000000000000000000..1f01b5c6c9db42f603f6507f2f33ef388f5b91d7 --- /dev/null +++ b/Documentation/dev-tools/kunit/api/uapi.rst @@ -0,0 +1,14 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================== +Userspace Test API +================== + +This file documents all of the userspace testing API. +Userspace tests are built as :ref:`kbuild userprogs <kbuild_userprogs>`, +linked statically and without any external dependencies. + +For the widest platform compatibility they should use nolibc, as provided by `init/Makefile.nolibc`. + +.. kernel-doc:: include/kunit/uapi.h + :internal: diff --git a/MAINTAINERS b/MAINTAINERS index e806158cc6798cf97a4aab58c038fb5351d469aa..0f60501c6de570723123b24eb930d15f1bd956eb 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -13540,6 +13540,12 @@ S: Maintained F: Documentation/devicetree/bindings/leds/backlight/kinetic,ktz8866.yaml F: drivers/video/backlight/ktz8866.c

+KUNIT UAPI TESTING FRAMEWORK (in addition to KERNEL UNIT TESTING FRAMEWORK) +M: Thomas Weißschuh thomas.weissschuh@linutronix.de +S: Maintained +F: include/kunit/uapi.h +F: lib/kunit/kunit-uapi.c + KVM PARAVIRT (KVM/paravirt) M: Paolo Bonzini pbonzini@redhat.com R: Vitaly Kuznetsov vkuznets@redhat.com diff --git a/include/kunit/uapi.h b/include/kunit/uapi.h new file mode 100644 index 0000000000000000000000000000000000000000..a5c923f5d82a91e0acd9dc17369f84f00b7d342f --- /dev/null +++ b/include/kunit/uapi.h @@ -0,0 +1,77 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * KUnit Userspace testing API. + * + * Copyright (C) 2025, Linutronix GmbH. + * Author: Thomas Weißschuh thomas.weissschuh@linutronix.de + */ + +#ifndef _KUNIT_UAPI_H +#define _KUNIT_UAPI_H + +#include <linux/types.h> + +struct kunit; + +/** + * struct kunit_uapi_blob - Blob embedded build artifact + * @path: Path of the embedded artifact. + * @data: Start of the embedded data in memory. + * @end: End of the embedded data in memory. + */ +struct kunit_uapi_blob { + const char *const path; + const u8 *data; + const u8 *end; +}; + +#if IS_ENABLED(CONFIG_KUNIT_UAPI) + +/** + * KUNIT_UAPI_EMBED_BLOB() - Embed another build artifact into the kernel + * @_name: The name of symbol under which the artifact is embedded. + * @_path: Path to the artifact on disk. + * + * Embeds a build artifact like a userspace executable into the kernel or current module. + * The build artifact is read from disk and needs to be already built. + */ +#define KUNIT_UAPI_EMBED_BLOB(_name, _path) \ + asm ( \ + " .pushsection .rodata, "a" \n" \ + " .global " __stringify(CONCATENATE(_name, _data)) " \n" \ + __stringify(CONCATENATE(_name, _data)) ": \n" \ + " .incbin " __stringify(_path) " \n" \ + " .size " __stringify(CONCATENATE(_name, _data)) ", " \ + ". - " __stringify(CONCATENATE(_name, _data)) " \n" \ + " .global " __stringify(CONCATENATE(_name, _end)) " \n" \ + __stringify(CONCATENATE(_name, _end)) ": \n" \ + " .popsection \n" \ + ); \ + \ + extern const char CONCATENATE(_name, _data)[]; \ + extern const char CONCATENATE(_name, _end)[]; \ + \ + static const struct kunit_uapi_blob _name = { \ + .path = _path, \ + .data = CONCATENATE(_name, _data), \ + .end = CONCATENATE(_name, _end), \ + } \ + +#else /* !CONFIG_KUNIT_UAPI */ + +/* Unresolved external reference, to be optimized away */ +#define KUNIT_UAPI_EMBED_BLOB(_name, _path) \ + extern const struct kunit_uapi_blob _name + +#endif /* CONFIG_KUNIT_UAPI */ + +/** + * kunit_uapi_run_kselftest() - Run a userspace kselftest as part of kunit + * @test: The test context object. + * @executable: kselftest executable to run + * + * Runs the kselftest and forwards its TAP output and exit status to kunit. + */ +void kunit_uapi_run_kselftest(struct kunit *test, const struct kunit_uapi_blob *executable); + +#endif /* _KUNIT_UAPI_H */ diff --git a/lib/kunit/Kconfig b/lib/kunit/Kconfig index a97897edd9642f3e5df7fdd9dee26ee5cf00d6a4..c88e6cf5610bc8246c94d16b9025461f0cd3b2d2 100644 --- a/lib/kunit/Kconfig +++ b/lib/kunit/Kconfig @@ -93,4 +93,18 @@ config KUNIT_AUTORUN_ENABLED In most cases this should be left as Y. Only if additional opt-in behavior is needed should this be set to N.

+config KUNIT_UAPI + tristate "KUnit UAPI testing framework" + depends on KUNIT + depends on CC_CAN_LINK_STATIC || ARCH_HAS_NOLIBC + depends on !LTO_CLANG # https://github.com/llvm/llvm-project/issues/112920 + select HEADERS_INSTALL + default KUNIT + help + Enables support for building and running userspace selftests as part of kunit. + These tests should be statically linked and use kselftest.h or kselftest_harness.h + for status reporting. + + In most cases this should be left as Y. + endif # KUNIT diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile index 656f1fa35abcc635e67d5b4cb1bc586b48415ac5..6059621a2d32c8e7384acda59793f05826af8c81 100644 --- a/lib/kunit/Makefile +++ b/lib/kunit/Makefile @@ -12,6 +12,8 @@ kunit-objs += test.o \ device.o \ platform.o

+obj-$(CONFIG_KUNIT_UAPI) += kunit-uapi.o + ifeq ($(CONFIG_KUNIT_DEBUGFS),y) kunit-objs += debugfs.o endif diff --git a/lib/kunit/kunit-uapi.c b/lib/kunit/kunit-uapi.c new file mode 100644 index 0000000000000000000000000000000000000000..cfe8440e16fde942a5f0fa7ac9d8ab90a737215b --- /dev/null +++ b/lib/kunit/kunit-uapi.c @@ -0,0 +1,300 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * KUnit Userspace testing API. + * + * Copyright (C) 2025, Linutronix GmbH. + * Author: Thomas Weißschuh thomas.weissschuh@linutronix.de + */ + +#include <linux/binfmts.h> +#include <linux/export.h> +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/fs_struct.h> +#include <linux/pid.h> +#include <linux/pipe_fs_i.h> +#include <linux/sched/task.h> +#include <linux/types.h> + +#include <kunit/test.h> +#include <kunit/uapi.h> + +#define KSFT_PASS 0 +#define KSFT_FAIL 1 +#define KSFT_XFAIL 2 +#define KSFT_XPASS 3 +#define KSFT_SKIP 4 + +static struct vfsmount *kunit_uapi_mount_ramfs(void) +{ + struct file_system_type *type; + struct vfsmount *mnt; + + type = get_fs_type("ramfs"); + if (!type) + return ERR_PTR(-ENODEV); + + /* FIXME + * The mount setup is supposed to look like this: + * kunit_uapi_mount_ramfs() sets up a private mount, + * with nothing visible except the new tmpfs. + * Then each executable execution gets a new namespace on top of that + * on which it can mount whatever it needs. + * However I didn't manage to set this up, so keep everything simple + * for now and let somebody familiar with the VFS figure this out. + */ + + mnt = kern_mount(type); + put_filesystem(type); + + return mnt; +} + +static int kunit_uapi_write_file(struct vfsmount *mnt, const char *name, mode_t mode, + const u8 *data, size_t size) +{ + struct file *file; + ssize_t written; + + file = file_open_root_mnt(mnt, name, O_CREAT | O_WRONLY, mode); + if (IS_ERR(file)) + return PTR_ERR(file); + + written = kernel_write(file, data, size, NULL); + filp_close(file, NULL); + if (written != size) { + if (written >= 0) + return -ENOMEM; + return written; + } + + /* Flush delayed fput so exec can open the file read-only */ + flush_delayed_fput(); + + return 0; +} + +static int kunit_uapi_write_executable(struct vfsmount *mnt, + const struct kunit_uapi_blob *executable) +{ + return kunit_uapi_write_file(mnt, kbasename(executable->path), 0755, + executable->data, executable->end - executable->data); +} + +struct kunit_uapi_user_mode_thread_ctx { + const char *executable; + + /* Signals mnt, out, pwd and tgid */ + struct completion setup_done; + struct vfsmount *mnt; + struct file *out; + struct path pwd; + pid_t tgid; + + /* Valid after wait(tgid) */ + int exec_err; +}; + +static int kunit_uapi_user_mode_thread_init(void *data) +{ + struct kunit_uapi_user_mode_thread_ctx *ctx = data; + const char *const argv[] = { + ctx->executable, + NULL + }; + struct file *out[2]; + int err; + + err = create_pipe_files(out, 0); + if (err) + return err; + + /* stdin, use the *write* end to the pipe to have an unreadable input */ + err = replace_fd(0, out[1], 0); + if (err < 0) { + fput(out[0]); + fput(out[1]); + return err; + } + + /* stdout */ + err = replace_fd(1, out[1], 0); + if (err < 0) { + replace_fd(0, NULL, 0); + fput(out[0]); + fput(out[1]); + return err; + } + + /* stderr */ + err = replace_fd(2, out[1], 0); + if (err < 0) { + replace_fd(0, NULL, 0); + replace_fd(1, NULL, 0); + fput(out[0]); + fput(out[1]); + return err; + } + + fput(out[1]); + + ctx->out = out[0]; + ctx->tgid = current->tgid; + + set_fs_pwd(current->fs, &ctx->pwd); + kernel_sigaction(SIGKILL, SIG_DFL); + kernel_sigaction(SIGABRT, SIG_DFL); + + complete(&ctx->setup_done); + ctx->exec_err = kernel_execve(ctx->executable, argv, NULL); + if (!ctx->exec_err) + return 0; + do_exit(0); +} + +static size_t kunit_uapi_printk_subtest_lines(struct kunit *test, char *buf, size_t s) +{ + const char *ptr = buf, *newline; + size_t n; + + while (s) { + newline = strnchr(ptr, s, '\n'); + if (!newline) + break; + + n = newline - ptr + 1; + + kunit_log(KERN_INFO, test, KUNIT_SUBSUBTEST_INDENT "%.*s", (int)n, ptr); + ptr += n; + s -= n; + } + + memmove(buf, ptr, s); + + return s; +} + +static int kunit_uapi_forward_to_printk(struct kunit *test, struct file *output) +{ + /* + * printk() automatically adds a newline after each message. + * Therefore only fully accumulated lines can be forwarded. + * Each line needs to fit into the buffer below. + */ + char buf[512]; + size_t s = 0; + ssize_t n; + + while (1) { + n = kernel_read(output, buf + s, sizeof(buf) - s, NULL); + if (n <= 0) + return n; + s = kunit_uapi_printk_subtest_lines(test, buf, s + n); + } +} + +static void kunit_uapi_kill_pid(pid_t pid) +{ + struct pid *p; + + p = find_get_pid(pid); + kill_pid(p, SIGKILL, 1); + put_pid(p); +} + +static int kunit_uapi_run_executable_in_mount(struct kunit *test, const char *executable, + struct vfsmount *mnt) +{ + struct kunit_uapi_user_mode_thread_ctx ctx = { + .setup_done = COMPLETION_INITIALIZER_ONSTACK(ctx.setup_done), + .executable = executable, + .pwd = { + .mnt = mnt, + .dentry = mnt->mnt_root, + }, + }; + int forward_err, wait_err, ret; + pid_t pid; + + /* If SIGCHLD is ignored do_wait won't populate the status. */ + kernel_sigaction(SIGCHLD, SIG_DFL); + pid = user_mode_thread(kunit_uapi_user_mode_thread_init, &ctx, SIGCHLD); + if (pid < 0) { + kernel_sigaction(SIGCHLD, SIG_IGN); + return pid; + } + + wait_for_completion(&ctx.setup_done); + + forward_err = kunit_uapi_forward_to_printk(test, ctx.out); + if (forward_err) + kunit_uapi_kill_pid(ctx.tgid); + + wait_err = kernel_wait(ctx.tgid, &ret); + + /* Restore default kernel sig handler */ + kernel_sigaction(SIGCHLD, SIG_IGN); + + if (ctx.exec_err) + return ctx.exec_err; + if (forward_err) + return forward_err; + if (wait_err < 0) + return wait_err; + return ret; +} + +static int kunit_uapi_run_executable(struct kunit *test, + const struct kunit_uapi_blob *executable) +{ + const char *exe_name = kbasename(executable->path); + struct vfsmount *mnt; + int err; + + mnt = kunit_uapi_mount_ramfs(); + if (IS_ERR(mnt)) + return PTR_ERR(mnt); + + err = kunit_uapi_write_executable(mnt, executable); + + if (!err) + err = kunit_uapi_run_executable_in_mount(test, exe_name, mnt); + + kern_unmount(mnt); + + return err; +} + +void kunit_uapi_run_kselftest(struct kunit *test, const struct kunit_uapi_blob *executable) +{ + u8 exit_code, exit_signal; + int err; + + err = kunit_uapi_run_executable(test, executable); + if (err < 0) + KUNIT_FAIL_AND_ABORT(test, "Could not run test executable: %pe\n", ERR_PTR(err)); + + exit_code = err >> 8; + exit_signal = err & 0xff; + + if (exit_signal) + KUNIT_FAIL_AND_ABORT(test, "kselftest exited with signal: %d\n", exit_signal); + else if (exit_code == KSFT_PASS) + ; /* Noop */ + else if (exit_code == KSFT_FAIL) + KUNIT_FAIL_AND_ABORT(test, "kselftest exited with code KSFT_FAIL\n"); + else if (exit_code == KSFT_XPASS) + KUNIT_FAIL_AND_ABORT(test, "kselftest exited with code KSFT_XPASS\n"); + else if (exit_code == KSFT_XFAIL) + ; /* Noop */ + else if (exit_code == KSFT_SKIP) + kunit_mark_skipped(test, "kselftest exited with code KSFT_SKIP\n"); + else + KUNIT_FAIL_AND_ABORT(test, "kselftest exited with unknown exit code: %d\n", + exit_code); +} +EXPORT_SYMBOL_GPL(kunit_uapi_run_kselftest); + +MODULE_DESCRIPTION("KUnit UAPI testing framework"); +MODULE_AUTHOR("Thomas Weißschuh <thomas.weissschuh@linutronix.de"); +MODULE_LICENSE("GPL");

UAPI selftests may expect a "normal" userspace environment. For example the normal kernel API pseudo-filesystems should be mounted. This could be done from kernel code but it is non-idiomatic.

Add a preinit userspace executable which performs these setup steps before running the final test executable. This preinit executable is only ever run from the kernel. Give it access to autoconf.h and kconfig.h to adapt itself to the tested kernel.

Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de Reviewed-by: David Gow davidgow@google.com --- MAINTAINERS | 1 + lib/kunit/Makefile | 6 +++++ lib/kunit/kunit-uapi.c | 9 +++++-- lib/kunit/uapi-preinit.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 77 insertions(+), 2 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS index b1405f0a0e638d1654d9dc9e51d784ddc838cf5b..e81dfa180ab374ef91c7a45e546e6e9a8f454fa7 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -13546,6 +13546,7 @@ S: Maintained F: include/kunit/uapi.h F: lib/kunit/kunit-example-uapi.c F: lib/kunit/kunit-uapi.c +F: lib/kunit/uapi-preinit.c

KVM PARAVIRT (KVM/paravirt) M: Paolo Bonzini pbonzini@redhat.com diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile index 1bba7965613e36e26939d6b31e1d65acf5bad0dc..b50f3bc8bc7f3ade03be4900d9163d7a0d96863c 100644 --- a/lib/kunit/Makefile +++ b/lib/kunit/Makefile @@ -14,8 +14,14 @@ kunit-objs += test.o \ device.o \ platform.o

+userprogs += uapi-preinit +uapi-preinit-userccflags += -static $(NOLIBC_USERCFLAGS) \ + -include include/generated/autoconf.h \ + -include $(srctree)/tools/include/linux/kconfig.h obj-$(CONFIG_KUNIT_UAPI) += kunit-uapi.o

+$(obj)/kunit-uapi.o: $(obj)/uapi-preinit + ifeq ($(CONFIG_KUNIT_DEBUGFS),y) kunit-objs += debugfs.o endif diff --git a/lib/kunit/kunit-uapi.c b/lib/kunit/kunit-uapi.c index cfe8440e16fde942a5f0fa7ac9d8ab90a737215b..7c87605b9ded9dbeb3968af8a8f4650ab5938887 100644 --- a/lib/kunit/kunit-uapi.c +++ b/lib/kunit/kunit-uapi.c @@ -25,6 +25,8 @@ #define KSFT_XPASS 3 #define KSFT_SKIP 4

+KUNIT_UAPI_EMBED_BLOB(kunit_uapi_preinit, "uapi-preinit"); + static struct vfsmount *kunit_uapi_mount_ramfs(void) { struct file_system_type *type; @@ -146,7 +148,7 @@ static int kunit_uapi_user_mode_thread_init(void *data) kernel_sigaction(SIGABRT, SIG_DFL);

complete(&ctx->setup_done); - ctx->exec_err = kernel_execve(ctx->executable, argv, NULL); + ctx->exec_err = kernel_execve(kbasename(kunit_uapi_preinit.path), argv, NULL); if (!ctx->exec_err) return 0; do_exit(0); @@ -255,7 +257,10 @@ static int kunit_uapi_run_executable(struct kunit *test, if (IS_ERR(mnt)) return PTR_ERR(mnt);

- err = kunit_uapi_write_executable(mnt, executable); + err = kunit_uapi_write_executable(mnt, &kunit_uapi_preinit); + + if (!err) + err = kunit_uapi_write_executable(mnt, executable);

if (!err) err = kunit_uapi_run_executable_in_mount(test, exe_name, mnt); diff --git a/lib/kunit/uapi-preinit.c b/lib/kunit/uapi-preinit.c new file mode 100644 index 0000000000000000000000000000000000000000..81182039965a8c93aebb2d5d76f4113bfef277a6 --- /dev/null +++ b/lib/kunit/uapi-preinit.c @@ -0,0 +1,63 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * KUnit Userspace environment setup. + * + * Copyright (C) 2025, Linutronix GmbH. + * Author: Thomas Weißschuh thomas.weissschuh@linutronix.de + * + * This is *userspace* code. + */ + +#include <sys/mount.h> +#include <sys/stat.h> + +#include "../../tools/testing/selftests/kselftest.h" + +static int setup_api_mount(const char *target, const char *fstype) +{ + int ret; + + ret = mkdir(target, 0755); + if (ret && errno != EEXIST) + return -errno; + + ret = mount("none", target, fstype, 0, NULL); + if (ret && errno != EBUSY) + return -errno; + + return 0; +} + +static void exit_failure(const char *stage, int err) +{ + /* If preinit fails synthesize a failed test report. */ + ksft_print_header(); + ksft_set_plan(1); + ksft_test_result_fail("Failed during test setup: %s: %s\n", stage, strerror(-err)); + ksft_finished(); +} + +int main(int argc, char **argv, char **envp) +{ + int ret; + + ret = setup_api_mount("/proc", "proc"); + if (ret) + exit_failure("mount /proc", ret); + + ret = setup_api_mount("/sys", "sysfs"); + if (ret) + exit_failure("mount /sys", ret); + + if (IS_ENABLED(CONFIG_DEVTMPFS)) { + ret = setup_api_mount("/dev", "devtmpfs"); + if (ret) + exit_failure("mount /dev", ret); + } + + ret = execve(argv[0], argv, envp); + if (ret) + exit_failure("execve", ret); + + return 0; +}