Hi, all.
Any comments?
On Thu, Feb 9, 2017 at 3:56 PM, Oleksandr Tyshchenko
<olekst...@gmail.com> wrote:
> 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
>
--
Regards,
Oleksandr Tyshchenko
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