[PATCH v4 3/5] libnvdimm/namespace: Enforce memremap_compat_align()
Dan Williams
dan.j.williams at intel.com
Wed Mar 4 13:08:19 AEDT 2020
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 at linux.ibm.com>
Cc: Jeff Moyer <jmoyer at redhat.com>
Fixes: a3619190d62e ("libnvdimm/pfn: stop padding pmem namespaces to section alignment")
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
Signed-off-by: Dan Williams <dan.j.williams at intel.com>
---
drivers/nvdimm/namespace_devs.c | 17 +++++++++++++++++
drivers/nvdimm/pfn.h | 12 ++++++++++++
drivers/nvdimm/pfn_devs.c | 32 +++++++++++++++++++++++++++++---
3 files changed, 58 insertions(+), 3 deletions(-)
diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index 032dc61725ff..77e211c7d94d 100644
--- 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 acb19517f678..37cb1b8a2a39 100644
--- 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 79fe02d6f657..34db557dbad1 100644
--- 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) {
/*
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