[PATCH v3 2/6] libnvdimm/namespace: Validate namespace start addr and size

["Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>]

Make sure namespace start addr and size are properly aligned as per architecture
restrictions. If the namespace is not aligned we mark the namespace 'disabled'

Architectures like ppc64 use different page size than PAGE_SIZE to map
direct-map address range. The kernel needs to make sure the namespace size is aligned
correctly for the direct-map page size.

kernel log will contain information as below.

[    5.810939] nd_pmem namespace0.1: invalid size/SPA
[    5.810969] nd_pmem: probe of namespace0.1 failed with error -95

and the namespace will be marked 'disabled'

  {
    "dev":"namespace0.1",
    "mode":"fsdax",
    "map":"mem",
    "size":1071644672,
    "uuid":"25577a00-c012-421d-89ca-3ee189e08848",
    "sector_size":512,
    "state":"disabled"
  },

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 drivers/nvdimm/namespace_devs.c | 39 +++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index 032dc61725ff..0751fd4b7d4a 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -1113,6 +1113,40 @@ resource_size_t nvdimm_namespace_capacity(struct nd_namespace_common *ndns)
 }
 EXPORT_SYMBOL(nvdimm_namespace_capacity);
 
+static bool nvdimm_valid_namespace(struct nd_namespace_common *ndns, resource_size_t size)
+{
+	struct device *dev = &ndns->dev;
+	struct nd_region *nd_region = to_nd_region(dev->parent);
+	unsigned long align_size = arch_namespace_align_size();
+	struct resource *res;
+	u32 remainder;
+
+	if (is_namespace_blk(dev))
+		return true;
+
+	div_u64_rem(size, align_size * nd_region->ndr_mappings, &remainder);
+	if (remainder)
+		return false;
+
+	if (is_namespace_pmem(dev)) {
+		struct nd_namespace_pmem *nspm = to_nd_namespace_pmem(dev);
+
+		res = &nspm->nsio.res;
+	} else if (is_namespace_io(dev)) {
+		struct nd_namespace_io *nsio = to_nd_namespace_io(dev);
+
+		res = &nsio->res;
+	} else
+		/* cannot reach */
+		return false;
+
+	div_u64_rem(res->start, align_size * nd_region->ndr_mappings, &remainder);
+	if (remainder)
+		return false;
+
+	return true;
+}
+
 bool nvdimm_namespace_locked(struct nd_namespace_common *ndns)
 {
 	int i;
@@ -1739,6 +1773,11 @@ struct nd_namespace_common *nvdimm_namespace_common_probe(struct device *dev)
 		return ERR_PTR(-ENODEV);
 	}
 
+	if (!nvdimm_valid_namespace(ndns, size)) {
+		dev_err(&ndns->dev, "invalid size/SPA");
+		return ERR_PTR(-EOPNOTSUPP);
+	}
+
 	if (is_namespace_pmem(&ndns->dev)) {
 		struct nd_namespace_pmem *nspm;
 
-- 
2.24.1
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