The duplication makes maintenance harder. Changes need to be done in two places and the lines will grow overly long.

Use an intermediary variable instead.

Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de Reviewed-by: Nicolas Schier n.schier@avm.de Acked-by: Masahiro Yamada masahiroy@kernel.org --- Makefile | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile index 35e6e5240c61a8a329011929fcd0352b881dccdc..c4293cf91e968ca8ee64452841fb266e24df63f6 100644 --- a/Makefile +++ b/Makefile @@ -1130,8 +1130,9 @@ LDFLAGS_vmlinux += --emit-relocs --discard-none endif

# Align the bit size of userspace programs with the kernel -KBUILD_USERCFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)) -KBUILD_USERLDFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)) +USERFLAGS_FROM_KERNEL := -m32 -m64 --target=% +KBUILD_USERCFLAGS += $(filter $(USERFLAGS_FROM_KERNEL), $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)) +KBUILD_USERLDFLAGS += $(filter $(USERFLAGS_FROM_KERNEL), $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))

# userspace programs are linked via the compiler, use the correct linker ifeq ($(CONFIG_CC_IS_CLANG)$(CONFIG_LD_IS_LLD),yy)

Some upcoming documentation will link directly to the userprogs section.

Add a label to the section so it can be referenced.

Reviewed-by: Nicolas Schier n.schier@avm.de Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de Acked-by: Masahiro Yamada masahiroy@kernel.org --- Documentation/kbuild/makefiles.rst | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst index 8aef3650c1f32b6b197e0dc777e26775d371a081..c14c1f632f6069c8751c8388a35bef539e19f9e8 100644 --- a/Documentation/kbuild/makefiles.rst +++ b/Documentation/kbuild/makefiles.rst @@ -891,6 +891,8 @@ This is possible in two ways: This will tell kbuild to build lxdialog even if not referenced in any rule.

+.. _kbuild_userprogs: + Userspace Program support =========================

Building userspace applications through the kbuild "userprogs" framework requires a libc. Kernel toolchains often do not contain a libc. In this case it is useful to use the nolibc library from the kernel tree. Nolibc does not support all architectures and requires compiler flags.

Add a kconfig option, so users can know where it is available and provide a variable for common options.

Reviewed-by: Nicolas Schier n.schier@avm.de Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de --- MAINTAINERS | 2 ++ init/Kconfig | 2 ++ init/Kconfig.nolibc | 15 +++++++++++++++ init/Makefile.nolibc | 13 +++++++++++++ 4 files changed, 32 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS index a92290fffa163f9fe8fe3f04bf66426f9a894409..e806158cc6798cf97a4aab58c038fb5351d469aa 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -17702,6 +17702,8 @@ M: Willy Tarreau w@1wt.eu M: Thomas Weißschuh linux@weissschuh.net S: Maintained T: git git://git.kernel.org/pub/scm/linux/kernel/git/nolibc/linux-nolibc.git +F: init/Kconfig.nolibc +F: init/Makefile.nolibc F: tools/include/nolibc/ F: tools/testing/selftests/nolibc/

diff --git a/init/Kconfig b/init/Kconfig index 26cafbad4f1560fb56b4bef31ae29baf54175661..0af62f135192e0470e16eb6bb2fbb45ac38f4b81 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -92,6 +92,8 @@ config CC_CAN_LINK_STATIC 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)

+source "init/Kconfig.nolibc" + # 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 diff --git a/init/Kconfig.nolibc b/init/Kconfig.nolibc new file mode 100644 index 0000000000000000000000000000000000000000..29cbc5437e70cbc5e256f00b74d0ab4801b40de7 --- /dev/null +++ b/init/Kconfig.nolibc @@ -0,0 +1,15 @@ +# SPDX-License-Identifier: GPL-2.0 + +config ARCH_HAS_NOLIBC + bool + default y if ARM + default y if ARM64 + default y if LOONGARCH + default y if M68K + default y if MIPS + default y if PPC + default y if RISCV + default y if S390 + default y if SPARC + default y if UML_X86 + default y if X86 diff --git a/init/Makefile.nolibc b/init/Makefile.nolibc new file mode 100644 index 0000000000000000000000000000000000000000..dacc78ab4c81c93f3a24ebeb70e34253842f9a53 --- /dev/null +++ b/init/Makefile.nolibc @@ -0,0 +1,13 @@ +# SPDX-License-Identifier: GPL-2.0 +# Compiler flags, which are necessary to build userspace applications with the +# in-kernel libc "nolibc". + +ifeq ($(and $(CONFIG_ARCH_HAS_NOLIBC),$(CONFIG_HEADERS_INSTALL)),y) + +NOLIBC_USERCFLAGS := -nostdlib -nostdinc -static -ffreestanding \ + -fno-asynchronous-unwind-tables -fno-stack-protector \ + -I$(objtree)/usr/include -I$(srctree)/tools/include/nolibc/ + +NOLIBC_USERLDFLAGS := -nostdlib -nostdinc -static + +endif # CONFIG_ARCH_HAS_NOLIBC && CONFIG_HEADERS_INSTALL

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 | 3 +++ tools/testing/kunit/kunit_tool_test.py | 1 + tools/testing/kunit/test_data/test_is_test_passed-failure-nested.log | 3 +++ 3 files changed, 7 insertions(+)

diff --git a/tools/testing/kunit/kunit_parser.py b/tools/testing/kunit/kunit_parser.py index c176487356e6c94882046b19ea696d750905b8d5..a7a61e627e348db14b953080ec8789994fba955a 100644 --- a/tools/testing/kunit/kunit_parser.py +++ b/tools/testing/kunit/kunit_parser.py @@ -687,6 +687,9 @@ def bubble_up_test_results(test: Test) -> None: elif test.counts.get_status() == TestStatus.TEST_CRASHED: test.status = TestStatus.TEST_CRASHED

+ if status == TestStatus.FAILURE and test.counts.get_status() == TestStatus.SUCCESS: + counts.add_status(status) + def parse_test(lines: LineStream, expected_num: int, log: List[str], is_subtest: bool, printer: Printer) -> Test: """ Finds next test to parse in LineStream, creates new Test object, diff --git a/tools/testing/kunit/kunit_tool_test.py b/tools/testing/kunit/kunit_tool_test.py index b74dc05fc2fe5b3ff629172fc7aafeb5c3d29fb3..d5bbcb95ab6abb1a8ee91439d87daaf29d159294 100755 --- a/tools/testing/kunit/kunit_tool_test.py +++ b/tools/testing/kunit/kunit_tool_test.py @@ -172,6 +172,7 @@ class KUnitParserTest(unittest.TestCase): self.assertEqual(kunit_parser.TestStatus.FAILURE, result.status) self.assertEqual(result.counts.failed, 2) 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

--- This is similar to the usermode helper framework, but not using it as there would be some issues. It gets neutered by CONFIG_STATIC_USERMODEHELPER_PATH. That could be worked around by overriding sub_info->path, but that would be a hack. Also it does not allow the implementation of a custom wait routine to forward the process output to KUnit as implemented in kunit_uapi_forward_to_printk(). That may be solved by adding another thread, or messing with the internals of the framework, but that would also be ugly. --- 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..24356f68eca0df07032fb8a9e92daffde01b21d3 --- /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 = 0; + 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 | 7 ++++++ lib/kunit/kunit-uapi.c | 9 +++++-- lib/kunit/uapi-preinit.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 78 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 2434470e998525e5667ebc207d11659835b5e888..e52a31b0852caef5669f11f6059c29ce5911aa43 100644 --- a/lib/kunit/Makefile +++ b/lib/kunit/Makefile @@ -14,8 +14,15 @@ 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

+CFLAGS_kunit-uapi.o := -Wa,-I$(obj) +$(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 24356f68eca0df07032fb8a9e92daffde01b21d3..382a2bfee3c78a6e042a56a9ccdefcd55b5265a1 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; +}