@@ -12,7 +12,14 @@ kunit-objs += test.o \
device.o \
platform.o
-kunit-$(CONFIG_KUNIT_UAPI) += uapi.o
+userprogs += uapi-preinit
+uapi-preinit-nolibc := $(CONFIG_ARCH_HAS_NOLIBC)
+uapi-preinit-userccflags += -static \
+ -include include/generated/autoconf.h \
+ -include $(srctree)/tools/include/linux/kconfig.h
+blobs += uapi-preinit.blob.o
+uapi-preinit.blob-symbol := kunit_uapi_preinit
+kunit-$(CONFIG_KUNIT_UAPI) += uapi.o uapi-preinit.blob.o
ifeq ($(CONFIG_KUNIT_DEBUGFS),y)
kunit-objs += debugfs.o
new file mode 100644
@@ -0,0 +1,65 @@
+// 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.
+ */
+
+#ifndef NOLIBC
+#include <sys/mount.h>
+#include <sys/stat.h>
+#endif
+
+#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;
+}
@@ -139,7 +139,7 @@ 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(BLOB(kunit_uapi_preinit)->path), argv, NULL);
if (!ctx->exec_err)
return 0;
do_exit(0);
@@ -239,6 +239,7 @@ static int kunit_uapi_run_executable_in_mount(struct kunit *test, const char *ex
static int kunit_uapi_run_executable(struct kunit *test, const struct blob *executable)
{
+ const struct blob *preinit = BLOB(kunit_uapi_preinit);
const char *exe_name = kbasename(executable->path);
struct vfsmount *mnt;
int err;
@@ -247,7 +248,13 @@ static int kunit_uapi_run_executable(struct kunit *test, const struct blob *exec
if (IS_ERR(mnt))
return PTR_ERR(mnt);
- err = kunit_uapi_write_file(mnt, exe_name, 0755, executable->data, blob_size(executable));
+ err = kunit_uapi_write_file(mnt, kbasename(preinit->path), 0755,
+ preinit->data,
+ blob_size(preinit));
+
+ if (!err)
+ err = kunit_uapi_write_file(mnt, exe_name, 0755,
+ executable->data, blob_size(executable));
if (!err)
err = kunit_uapi_run_executable_in_mount(test, exe_name, mnt);
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> --- lib/kunit/Makefile | 9 ++++++- lib/kunit/uapi-preinit.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++ lib/kunit/uapi.c | 11 ++++++-- 3 files changed, 82 insertions(+), 3 deletions(-)