From: Oleksandr Tyshchenko <oleksandr_tyshche...@epam.com>
Do a check for already installed leaf entry at the current level before
performing any actions when trying to map.
This check is already present in arm_lpae_init_pte(), i.e. before
installing new leaf entry at the current level if conditions to do so
are met (size == block_size).
But, this might be insufficient in case when we have already
installed block mapping at this level and it is not time to
install new leaf entry (size != block_size).
In that case we continue walking the page table down with wrong pointer
to the next level.
So, move check from arm_lpae_init_pte() to __arm_lpae_map() in order to
avoid all cases.
Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshche...@epam.com>
---
I hope that following actions can help to catch it:
1. Call iommu_map for a block mapping (e.g. 2M) at some address
(e.g. iova 0x80000000 pa 0x80000000).
2. Call iommu_map for a page mapping (4k) at some address from
the previous mapped region (e.g. iova 0x80008000 pa 0x90000000).
I understand that after iommu_map should be iommu_unmap, but
different scenarios may occur).
---
---
drivers/iommu/io-pgtable-arm.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index f5c90e1..ebdb82f 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -272,11 +272,7 @@ static int arm_lpae_init_pte(struct arm_lpae_io_pgtable
*data,
arm_lpae_iopte pte = prot;
struct io_pgtable_cfg *cfg = &data->iop.cfg;
- if (iopte_leaf(*ptep, lvl)) {
- /* We require an unmap first */
- WARN_ON(!selftest_running);
- return -EEXIST;
- } else if (iopte_type(*ptep, lvl) == ARM_LPAE_PTE_TYPE_TABLE) {
+ if (iopte_type(*ptep, lvl) == ARM_LPAE_PTE_TYPE_TABLE) {
/*
* We need to unmap and free the old table before
* overwriting it with a block entry.
@@ -315,6 +311,13 @@ static int __arm_lpae_map(struct arm_lpae_io_pgtable
*data, unsigned long iova,
/* Find our entry at the current level */
ptep += ARM_LPAE_LVL_IDX(iova, lvl, data);
+ /* Check for already installed leaf entry */
+ if (iopte_leaf(*ptep, lvl)) {
+ /* We require an unmap first */
+ WARN_ON(!selftest_running);
+ return -EEXIST;
+ }
+
/* If we can install a leaf entry at this level, then do so */
if (size == block_size && (size & cfg->pgsize_bitmap))
return arm_lpae_init_pte(data, iova, paddr, prot, lvl, ptep);
--
2.7.4
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