Re: [PATCH v4 12/15] kunit: Introduce UAPI testing framework

[Benjamin Berg <benjamin@sipsolutions.net>]

Hi Thomas,

I ran into two minor issues trying out the patches, see inline.

On Thu, 2025-06-26 at 08:10 +0200, Thomas Weißschuh wrote:
> 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>
> 
> [SNIP]
> +/**
> + * 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),				\
> +	}									\

For me, the compiler could not find the files for the ".incbin" unless
I added an include path. i.e. adding
  ccflags-y := -I$(obj)
to lib/kunit/Makefile fixed the problem for me.

> [SNIP]
> +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;

ret needs to be initialized to zero here as the kernel_wait function
will only set "ret" if wo.wo_stat is non-zero.

Benjamin

> [SNIP]