From: John Groves <[email protected]>
Two fixes for virtual address handling in fsdev:
1. Use __va(phys) instead of virt_addr + linear_offset for the kaddr
return in __fsdev_dax_direct_access(). The previous code added a
device-linear byte offset to virt_addr (which is __va of ranges[0]),
but for multi-range devices with physical gaps between ranges, this
linear arithmetic crosses the gap and produces a wrong kernel virtual
address. Using __va(phys) where phys comes from dax_pgoff_to_phys()
is correct for any range layout because the direct map translates
each physical address independently.
2. Convert the WARN_ON to a fatal error when pgmap_phys > phys. This
condition means the remapped region starts after the device's data
region, which is an impossible state. Previously the probe continued
with data_offset=0, leaving virt_addr silently misaligned. Now probe
returns -EINVAL with a diagnostic message.
Fixes: 759455848df0b ("dax: Save the kva from memremap")
Signed-off-by: John Groves <[email protected]>
---
drivers/dax/fsdev.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/dax/fsdev.c b/drivers/dax/fsdev.c
index de7e6dee68386..bf0ba1f1f0b76 100644
--- a/drivers/dax/fsdev.c
+++ b/drivers/dax/fsdev.c
@@ -51,7 +51,6 @@ static long __fsdev_dax_direct_access(struct dax_device
*dax_dev, pgoff_t pgoff,
struct dev_dax *dev_dax = dax_get_private(dax_dev);
size_t size = nr_pages << PAGE_SHIFT;
size_t offset = pgoff << PAGE_SHIFT;
- void *virt_addr = dev_dax->virt_addr + offset;
phys_addr_t phys;
phys = dax_pgoff_to_phys(dev_dax, pgoff, size);
@@ -62,7 +61,7 @@ static long __fsdev_dax_direct_access(struct dax_device
*dax_dev, pgoff_t pgoff,
}
if (kaddr)
- *kaddr = virt_addr;
+ *kaddr = __va(phys);
if (pfn)
*pfn = PHYS_PFN(phys);
@@ -311,8 +310,13 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax)
u64 phys = dev_dax->ranges[0].range.start;
u64 pgmap_phys = dev_dax->pgmap[0].range.start;
- if (!WARN_ON(pgmap_phys > phys))
- data_offset = phys - pgmap_phys;
+ if (pgmap_phys > phys) {
+ dev_err(dev, "pgmap start %#llx exceeds data start
%#llx\n",
+ pgmap_phys, phys);
+ rc = -EINVAL;
+ goto err_pgmap;
+ }
+ data_offset = phys - pgmap_phys;
pr_debug("%s: offset detected phys=%llx pgmap_phys=%llx
offset=%llx\n",
__func__, phys, pgmap_phys, data_offset);
--
2.53.0
