libnvdimm/namespace: Enforce memremap_compat_align()

The pmem driver on PowerPC crashes with the following signature when
instantiating misaligned namespaces that map their capacity via
memremap_pages().

    BUG: Unable to handle kernel data access at 0xc001000406000000
    Faulting instruction address: 0xc000000000090790
    NIP [c000000000090790] arch_add_memory+0xc0/0x130
    LR [c000000000090744] arch_add_memory+0x74/0x130
    Call Trace:
     arch_add_memory+0x74/0x130 (unreliable)
     memremap_pages+0x74c/0xa30
     devm_memremap_pages+0x3c/0xa0
     pmem_attach_disk+0x188/0x770
     nvdimm_bus_probe+0xd8/0x470

With the assumption that only memremap_pages() has alignment
constraints, enforce memremap_compat_align() for
pmem_should_map_pages(), nd_pfn, and nd_dax cases. This includes
preventing the creation of namespaces where the base address is
misaligned and cases there infoblock padding parameters are invalid.

Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Fixes: a3619190d62e ("libnvdimm/pfn: stop padding pmem namespaces to section alignment")
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index 032dc61..77e211c 100644 (file)
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -10,6 +10,7 @@
 #include <linux/nd.h>
 #include "nd-core.h"
 #include "pmem.h"
+#include "pfn.h"
 #include "nd.h"
 
 static void namespace_io_release(struct device *dev)
@@ -1739,6 +1740,22 @@ struct nd_namespace_common *nvdimm_namespace_common_probe(struct device *dev)
                return ERR_PTR(-ENODEV);
        }
 
+       /*
+        * Note, alignment validation for fsdax and devdax mode
+        * namespaces happens in nd_pfn_validate() where infoblock
+        * padding parameters can be applied.
+        */
+       if (pmem_should_map_pages(dev)) {
+               struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
+               struct resource *res = &nsio->res;
+
+               if (!IS_ALIGNED(res->start | (res->end + 1),
+                                       memremap_compat_align())) {
+                       dev_err(&ndns->dev, "%pr misaligned, unable to map\n", res);
+                       return ERR_PTR(-EOPNOTSUPP);
+               }
+       }
+
        if (is_namespace_pmem(&ndns->dev)) {
                struct nd_namespace_pmem *nspm;
 

diff --git a/drivers/nvdimm/pfn.h b/drivers/nvdimm/pfn.h
index acb1951..37cb1b8 100644 (file)
--- a/drivers/nvdimm/pfn.h
+++ b/drivers/nvdimm/pfn.h
@@ -24,6 +24,18 @@ struct nd_pfn_sb {
        __le64 npfns;
        __le32 mode;
        /* minor-version-1 additions for section alignment */
+       /**
+        * @start_pad: Deprecated attribute to pad start-misaligned namespaces
+        *
+        * start_pad is deprecated because the original definition did
+        * not comprehend that dataoff is relative to the base address
+        * of the namespace not the start_pad adjusted base. The result
+        * is that the dax path is broken, but the block-I/O path is
+        * not. The kernel will no longer create namespaces using start
+        * padding, but it still supports block-I/O for legacy
+        * configurations mainly to allow a backup, reconfigure the
+        * namespace, and restore flow to repair dax operation.
+        */
        __le32 start_pad;
        __le32 end_trunc;
        /* minor-version-2 record the base alignment of the mapping */

diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index 79fe02d..34db557 100644 (file)
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -446,6 +446,7 @@ static bool nd_supported_alignment(unsigned long align)
 int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
 {
        u64 checksum, offset;
+       struct resource *res;
        enum nd_pfn_mode mode;
        struct nd_namespace_io *nsio;
        unsigned long align, start_pad;
@@ -578,13 +579,14 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
         * established.
         */
        nsio = to_nd_namespace_io(&ndns->dev);
-       if (offset >= resource_size(&nsio->res)) {
+       res = &nsio->res;
+       if (offset >= resource_size(res)) {
                dev_err(&nd_pfn->dev, "pfn array size exceeds capacity of %s\n",
                                dev_name(&ndns->dev));
                return -EOPNOTSUPP;
        }
 
-       if ((align && !IS_ALIGNED(nsio->res.start + offset + start_pad, align))
+       if ((align && !IS_ALIGNED(res->start + offset + start_pad, align))
                        || !IS_ALIGNED(offset, PAGE_SIZE)) {
                dev_err(&nd_pfn->dev,
                                "bad offset: %#llx dax disabled align: %#lx\n",
@@ -592,6 +594,18 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
                return -EOPNOTSUPP;
        }
 
+       if (!IS_ALIGNED(res->start + le32_to_cpu(pfn_sb->start_pad),
+                               memremap_compat_align())) {
+               dev_err(&nd_pfn->dev, "resource start misaligned\n");
+               return -EOPNOTSUPP;
+       }
+
+       if (!IS_ALIGNED(res->end + 1 - le32_to_cpu(pfn_sb->end_trunc),
+                               memremap_compat_align())) {
+               dev_err(&nd_pfn->dev, "resource end misaligned\n");
+               return -EOPNOTSUPP;
+       }
+
        return 0;
 }
 EXPORT_SYMBOL(nd_pfn_validate);
@@ -750,7 +764,19 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn)
        start = nsio->res.start;
        size = resource_size(&nsio->res);
        npfns = PHYS_PFN(size - SZ_8K);
-       align = max(nd_pfn->align, SUBSECTION_SIZE);
+       align = max(nd_pfn->align, memremap_compat_align());
+
+       /*
+        * When @start is misaligned fail namespace creation. See
+        * the 'struct nd_pfn_sb' commentary on why ->start_pad is not
+        * an option.
+        */
+       if (!IS_ALIGNED(start, memremap_compat_align())) {
+               dev_err(&nd_pfn->dev, "%s: start %pa misaligned to %#lx\n",
+                               dev_name(&ndns->dev), &start,
+                               memremap_compat_align());
+               return -EINVAL;
+       }
        end_trunc = start + size - ALIGN_DOWN(start + size, align);
        if (nd_pfn->mode == PFN_MODE_PMEM) {
                /*