Commit 6acd7d5e authored by Dan Williams's avatar Dan Williams
Browse files

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: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Fixes: a3619190 ("libnvdimm/pfn: stop padding pmem namespaces to section alignment")
Reviewed-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent b2ba7e91

drivers/nvdimm/namespace_devs.c

+17 −0
Original line number Diff line number Diff line
@@ -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;

drivers/nvdimm/pfn.h

+12 −0
Original line number Diff line number Diff line
@@ -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 */

drivers/nvdimm/pfn_devs.c

+29 −3
Original line number Diff line number Diff line
@@ -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) {

		/*

CRA Git | Maintained and supported by SUSTech CRA and CCSE