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Commit 6bc75619 authored by Dan Williams's avatar Dan Williams
Browse files

tools/testing/nvdimm: libnvdimm unit test infrastructure 

'libnvdimm' is the first driver sub-system in the kernel to implement
mocking for unit test coverage.  The nfit_test module gets built as an
external module and arranges for external module replacements of nfit,
libnvdimm, nd_pmem, and nd_blk.  These replacements use the linker
--wrap option to redirect calls to ioremap() + request_mem_region() to
custom defined unit test resources.  The end result is a fully
functional nvdimm_bus, as far as userspace is concerned, but with the
capability to perform otherwise destructive tests on emulated resources.

Q: Why not use QEMU for this emulation?
QEMU is not suitable for unit testing.  QEMU's role is to faithfully
emulate the platform.  A unit test's role is to unfaithfully implement
the platform with the goal of triggering bugs in the corners of the
sub-system implementation.  As bugs are discovered in platforms, or the
sub-system itself, the unit tests are extended to backstop a fix with a
reproducer unit test.

Another problem with QEMU is that it would require coordination of 3
software projects instead of 2 (kernel + libndctl [1]) to maintain and
execute the tests.  The chances for bit rot and the difficulty of
getting the tests running goes up non-linearly the more components
involved.


Q: Why submit this to the kernel tree instead of external modules in
   libndctl?
Simple, to alleviate the same risk that out-of-tree external modules
face.  Updates to drivers/nvdimm/ can be immediately evaluated to see if
they have any impact on tools/testing/nvdimm/.


Q: What are the negative implications of merging this?
It is a unique maintenance burden because the purpose of mocking an
interface to enable a unit test is to purposefully short circuit the
semantics of a routine to enable testing.  For example
__wrap_ioremap_cache() fakes the pmem driver into "ioremap()'ing" a test
resource buffer allocated by dma_alloc_coherent().  The future
maintenance burden hits when someone changes the semantics of
ioremap_cache() and wonders what the implications are for the unit test.

[1]: https://github.com/pmem/ndctl



Cc: <linux-acpi@vger.kernel.org>
Cc: Lv Zheng <lv.zheng@intel.com>
Cc: Robert Moore <robert.moore@intel.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 047fc8a1

drivers/acpi/nfit.c

+8 −4
Original line number Original line Diff line number Diff line
@@ -33,10 +33,11 @@ MODULE_PARM_DESC(force_enable_dimms, "Ignore _STA (ACPI DIMM device) status"); 




static u8 nfit_uuid[NFIT_UUID_MAX][16];

static u8 nfit_uuid[NFIT_UUID_MAX][16];





static const u8 *to_nfit_uuid(enum nfit_uuids id)

const u8 *to_nfit_uuid(enum nfit_uuids id)

{

{

	return nfit_uuid[id];

	return nfit_uuid[id];

}

}

EXPORT_SYMBOL(to_nfit_uuid);





static struct acpi_nfit_desc *to_acpi_nfit_desc(

static struct acpi_nfit_desc *to_acpi_nfit_desc(

		struct nvdimm_bus_descriptor *nd_desc)

		struct nvdimm_bus_descriptor *nd_desc)
@@ -581,11 +582,12 @@ static struct attribute_group acpi_nfit_attribute_group = { 
	.attrs = acpi_nfit_attributes,

	.attrs = acpi_nfit_attributes,

};

};





static const struct attribute_group *acpi_nfit_attribute_groups[] = {

const struct attribute_group *acpi_nfit_attribute_groups[] = {

	&nvdimm_bus_attribute_group,

	&nvdimm_bus_attribute_group,

	&acpi_nfit_attribute_group,

	&acpi_nfit_attribute_group,

	NULL,

	NULL,

};

};

EXPORT_SYMBOL_GPL(acpi_nfit_attribute_groups);





static struct acpi_nfit_memory_map *to_nfit_memdev(struct device *dev)

static struct acpi_nfit_memory_map *to_nfit_memdev(struct device *dev)

{

{
@@ -1323,7 +1325,7 @@ static int acpi_nfit_init_mapping(struct acpi_nfit_desc *acpi_desc, 
		ndbr_desc = to_blk_region_desc(ndr_desc);

		ndbr_desc = to_blk_region_desc(ndr_desc);

		ndbr_desc->enable = acpi_nfit_blk_region_enable;

		ndbr_desc->enable = acpi_nfit_blk_region_enable;

		ndbr_desc->disable = acpi_nfit_blk_region_disable;

		ndbr_desc->disable = acpi_nfit_blk_region_disable;

		ndbr_desc->do_io = acpi_nfit_blk_region_do_io;

		ndbr_desc->do_io = acpi_desc->blk_do_io;

		if (!nvdimm_blk_region_create(acpi_desc->nvdimm_bus, ndr_desc))

		if (!nvdimm_blk_region_create(acpi_desc->nvdimm_bus, ndr_desc))

			return -ENOMEM;

			return -ENOMEM;

		break;

		break;
@@ -1407,7 +1409,7 @@ static int acpi_nfit_register_regions(struct acpi_nfit_desc *acpi_desc) 
	return 0;

	return 0;

}

}





static int acpi_nfit_init(struct acpi_nfit_desc *acpi_desc, acpi_size sz)

int acpi_nfit_init(struct acpi_nfit_desc *acpi_desc, acpi_size sz)

{

{

	struct device *dev = acpi_desc->dev;

	struct device *dev = acpi_desc->dev;

	const void *end;

	const void *end;
@@ -1446,6 +1448,7 @@ static int acpi_nfit_init(struct acpi_nfit_desc *acpi_desc, acpi_size sz) 




	return acpi_nfit_register_regions(acpi_desc);

	return acpi_nfit_register_regions(acpi_desc);

}

}

EXPORT_SYMBOL_GPL(acpi_nfit_init);





static int acpi_nfit_add(struct acpi_device *adev)

static int acpi_nfit_add(struct acpi_device *adev)

{

{
@@ -1470,6 +1473,7 @@ static int acpi_nfit_add(struct acpi_device *adev) 
	dev_set_drvdata(dev, acpi_desc);

	dev_set_drvdata(dev, acpi_desc);

	acpi_desc->dev = dev;

	acpi_desc->dev = dev;

	acpi_desc->nfit = (struct acpi_table_nfit *) tbl;

	acpi_desc->nfit = (struct acpi_table_nfit *) tbl;

	acpi_desc->blk_do_io = acpi_nfit_blk_region_do_io;

	nd_desc = &acpi_desc->nd_desc;

	nd_desc = &acpi_desc->nd_desc;

	nd_desc->provider_name = "ACPI.NFIT";

	nd_desc->provider_name = "ACPI.NFIT";

	nd_desc->ndctl = acpi_nfit_ctl;

	nd_desc->ndctl = acpi_nfit_ctl;

drivers/acpi/nfit.h

+6 −0
Original line number Original line Diff line number Diff line
@@ -93,6 +93,8 @@ struct acpi_nfit_desc { 
	struct nvdimm_bus *nvdimm_bus;

	struct nvdimm_bus *nvdimm_bus;

	struct device *dev;

	struct device *dev;

	unsigned long dimm_dsm_force_en;

	unsigned long dimm_dsm_force_en;

	int (*blk_do_io)(struct nd_blk_region *ndbr, resource_size_t dpa,

			void *iobuf, u64 len, int rw);

};

};





enum nd_blk_mmio_selector {

enum nd_blk_mmio_selector {
@@ -146,4 +148,8 @@ static inline struct acpi_nfit_desc *to_acpi_desc( 
{

{

	return container_of(nd_desc, struct acpi_nfit_desc, nd_desc);

	return container_of(nd_desc, struct acpi_nfit_desc, nd_desc);

}

}



const u8 *to_nfit_uuid(enum nfit_uuids id);

int acpi_nfit_init(struct acpi_nfit_desc *nfit, acpi_size sz);

extern const struct attribute_group *acpi_nfit_attribute_groups[];

#endif /* __NFIT_H__ */
 
#endif /* __NFIT_H__ */

tools/testing/nvdimm/Kbuild

0 → 100644
+40 −0
Original line number Original line Diff line number Diff line 
ldflags-y += --wrap=ioremap_cache

ldflags-y += --wrap=ioremap_nocache

ldflags-y += --wrap=iounmap

ldflags-y += --wrap=__request_region

ldflags-y += --wrap=__release_region



DRIVERS := ../../../drivers

NVDIMM_SRC := $(DRIVERS)/nvdimm

ACPI_SRC := $(DRIVERS)/acpi



obj-$(CONFIG_LIBNVDIMM) += libnvdimm.o

obj-$(CONFIG_BLK_DEV_PMEM) += nd_pmem.o

obj-$(CONFIG_ND_BTT) += nd_btt.o

obj-$(CONFIG_ND_BLK) += nd_blk.o

obj-$(CONFIG_ACPI_NFIT) += nfit.o



nfit-y := $(ACPI_SRC)/nfit.o

nfit-y += config_check.o



nd_pmem-y := $(NVDIMM_SRC)/pmem.o

nd_pmem-y += config_check.o



nd_btt-y := $(NVDIMM_SRC)/btt.o

nd_btt-y += config_check.o



nd_blk-y := $(NVDIMM_SRC)/blk.o

nd_blk-y += config_check.o



libnvdimm-y := $(NVDIMM_SRC)/core.o

libnvdimm-y += $(NVDIMM_SRC)/bus.o

libnvdimm-y += $(NVDIMM_SRC)/dimm_devs.o

libnvdimm-y += $(NVDIMM_SRC)/dimm.o

libnvdimm-y += $(NVDIMM_SRC)/region_devs.o

libnvdimm-y += $(NVDIMM_SRC)/region.o

libnvdimm-y += $(NVDIMM_SRC)/namespace_devs.o

libnvdimm-y += $(NVDIMM_SRC)/label.o

libnvdimm-$(CONFIG_BTT) += $(NVDIMM_SRC)/btt_devs.o

libnvdimm-y += config_check.o



obj-m += test/

tools/testing/nvdimm/Makefile

0 → 100644
+7 −0
Original line number Original line Diff line number Diff line 
KDIR ?= ../../../



default:

	$(MAKE) -C $(KDIR) M=$$PWD



install: default

	$(MAKE) -C $(KDIR) M=$$PWD modules_install

tools/testing/nvdimm/config_check.c

0 → 100644
+15 −0
Original line number Original line Diff line number Diff line 
#include <linux/kconfig.h>

#include <linux/bug.h>



void check(void)

{

	/*

	 * These kconfig symbols must be set to "m" for nfit_test to

	 * load and operate.

	 */

	BUILD_BUG_ON(!IS_MODULE(CONFIG_LIBNVDIMM));

	BUILD_BUG_ON(!IS_MODULE(CONFIG_BLK_DEV_PMEM));

	BUILD_BUG_ON(!IS_MODULE(CONFIG_ND_BTT));

	BUILD_BUG_ON(!IS_MODULE(CONFIG_ND_BLK));

	BUILD_BUG_ON(!IS_MODULE(CONFIG_ACPI_NFIT));

}