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authorDan Williams <dan.j.williams@intel.com>2015-06-18 00:23:32 +0300
committerDan Williams <dan.j.williams@intel.com>2015-06-26 18:23:38 +0300
commit6bc756193ff61bf5e7b3cfedfbb0873bf40f8055 (patch)
tree5b17fac71bf9989eb2f5ab4ff10e3c6fc01a3cbf /tools/testing/nvdimm/test/iomap.c
parent047fc8a1f9a6330eacc80374dff087e20dc2304b (diff)
downloadlinux-6bc756193ff61bf5e7b3cfedfbb0873bf40f8055.tar.xz
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: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'tools/testing/nvdimm/test/iomap.c')
-rw-r--r--tools/testing/nvdimm/test/iomap.c151
1 files changed, 151 insertions, 0 deletions
diff --git a/tools/testing/nvdimm/test/iomap.c b/tools/testing/nvdimm/test/iomap.c
new file mode 100644
index 000000000000..c85a6f6ba559
--- /dev/null
+++ b/tools/testing/nvdimm/test/iomap.c
@@ -0,0 +1,151 @@
+/*
+ * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#include <linux/rculist.h>
+#include <linux/export.h>
+#include <linux/ioport.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/io.h>
+#include "nfit_test.h"
+
+static LIST_HEAD(iomap_head);
+
+static struct iomap_ops {
+ nfit_test_lookup_fn nfit_test_lookup;
+ struct list_head list;
+} iomap_ops = {
+ .list = LIST_HEAD_INIT(iomap_ops.list),
+};
+
+void nfit_test_setup(nfit_test_lookup_fn lookup)
+{
+ iomap_ops.nfit_test_lookup = lookup;
+ list_add_rcu(&iomap_ops.list, &iomap_head);
+}
+EXPORT_SYMBOL(nfit_test_setup);
+
+void nfit_test_teardown(void)
+{
+ list_del_rcu(&iomap_ops.list);
+ synchronize_rcu();
+}
+EXPORT_SYMBOL(nfit_test_teardown);
+
+static struct nfit_test_resource *get_nfit_res(resource_size_t resource)
+{
+ struct iomap_ops *ops;
+
+ ops = list_first_or_null_rcu(&iomap_head, typeof(*ops), list);
+ if (ops)
+ return ops->nfit_test_lookup(resource);
+ return NULL;
+}
+
+void __iomem *__nfit_test_ioremap(resource_size_t offset, unsigned long size,
+ void __iomem *(*fallback_fn)(resource_size_t, unsigned long))
+{
+ struct nfit_test_resource *nfit_res;
+
+ rcu_read_lock();
+ nfit_res = get_nfit_res(offset);
+ rcu_read_unlock();
+ if (nfit_res)
+ return (void __iomem *) nfit_res->buf + offset
+ - nfit_res->res->start;
+ return fallback_fn(offset, size);
+}
+
+void __iomem *__wrap_ioremap_cache(resource_size_t offset, unsigned long size)
+{
+ return __nfit_test_ioremap(offset, size, ioremap_cache);
+}
+EXPORT_SYMBOL(__wrap_ioremap_cache);
+
+void __iomem *__wrap_ioremap_nocache(resource_size_t offset, unsigned long size)
+{
+ return __nfit_test_ioremap(offset, size, ioremap_nocache);
+}
+EXPORT_SYMBOL(__wrap_ioremap_nocache);
+
+void __wrap_iounmap(volatile void __iomem *addr)
+{
+ struct nfit_test_resource *nfit_res;
+
+ rcu_read_lock();
+ nfit_res = get_nfit_res((unsigned long) addr);
+ rcu_read_unlock();
+ if (nfit_res)
+ return;
+ return iounmap(addr);
+}
+EXPORT_SYMBOL(__wrap_iounmap);
+
+struct resource *__wrap___request_region(struct resource *parent,
+ resource_size_t start, resource_size_t n, const char *name,
+ int flags)
+{
+ struct nfit_test_resource *nfit_res;
+
+ if (parent == &iomem_resource) {
+ rcu_read_lock();
+ nfit_res = get_nfit_res(start);
+ rcu_read_unlock();
+ if (nfit_res) {
+ struct resource *res = nfit_res->res + 1;
+
+ if (start + n > nfit_res->res->start
+ + resource_size(nfit_res->res)) {
+ pr_debug("%s: start: %llx n: %llx overflow: %pr\n",
+ __func__, start, n,
+ nfit_res->res);
+ return NULL;
+ }
+
+ res->start = start;
+ res->end = start + n - 1;
+ res->name = name;
+ res->flags = resource_type(parent);
+ res->flags |= IORESOURCE_BUSY | flags;
+ pr_debug("%s: %pr\n", __func__, res);
+ return res;
+ }
+ }
+ return __request_region(parent, start, n, name, flags);
+}
+EXPORT_SYMBOL(__wrap___request_region);
+
+void __wrap___release_region(struct resource *parent, resource_size_t start,
+ resource_size_t n)
+{
+ struct nfit_test_resource *nfit_res;
+
+ if (parent == &iomem_resource) {
+ rcu_read_lock();
+ nfit_res = get_nfit_res(start);
+ rcu_read_unlock();
+ if (nfit_res) {
+ struct resource *res = nfit_res->res + 1;
+
+ if (start != res->start || resource_size(res) != n)
+ pr_info("%s: start: %llx n: %llx mismatch: %pr\n",
+ __func__, start, n, res);
+ else
+ memset(res, 0, sizeof(*res));
+ return;
+ }
+ }
+ __release_region(parent, start, n);
+}
+EXPORT_SYMBOL(__wrap___release_region);
+
+MODULE_LICENSE("GPL v2");