> -----Original Message----- > From: grundler@xxxxxxxxxx [mailto:grundler@xxxxxxxxxx] On Behalf Of Grant Grundler > Sent: Saturday, July 27, 2013 1:17 AM > To: Cho KyongHo > > On Fri, Jul 26, 2013 at 4:27 AM, Cho KyongHo <pullip.cho@xxxxxxxxxxx> wrote: > > This prevents allocating lv2 page table for the lv1 page table entry > > that already has 1MB page mapping. In addition some BUG_ON() is > > changed to WARN_ON(). > > > > Signed-off-by: Cho KyongHo <pullip.cho@xxxxxxxxxxx> > > Reviewed-by: Grant Grundler <grundler@xxxxxxxxxxxx> > > In reviewing this, I noticed another issue that is related, but not > caused by this patch. See below. > > > --- > > drivers/iommu/exynos-iommu.c | 52 +++++++++++++++++++++++++++++------------ > > 1 files changed, 37 insertions(+), 15 deletions(-) > > > > diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c > > index e3be3e5..6c4ecce 100644 > > --- a/drivers/iommu/exynos-iommu.c > > +++ b/drivers/iommu/exynos-iommu.c > > @@ -52,11 +52,11 @@ > > #define lv2ent_large(pent) ((*(pent) & 3) == 1) > > > > #define section_phys(sent) (*(sent) & SECT_MASK) > > -#define section_offs(iova) ((iova) & 0xFFFFF) > > +#define section_offs(iova) ((iova) & ~SECT_MASK) > > #define lpage_phys(pent) (*(pent) & LPAGE_MASK) > > -#define lpage_offs(iova) ((iova) & 0xFFFF) > > +#define lpage_offs(iova) ((iova) & ~LPAGE_MASK) > > #define spage_phys(pent) (*(pent) & SPAGE_MASK) > > -#define spage_offs(iova) ((iova) & 0xFFF) > > +#define spage_offs(iova) ((iova) & ~SPAGE_MASK) > > > > #define lv1ent_offset(iova) ((iova) >> SECT_ORDER) > > #define lv2ent_offset(iova) (((iova) & 0xFF000) >> SPAGE_ORDER) > > @@ -862,12 +862,14 @@ static unsigned long *alloc_lv2entry(unsigned long *sent, unsigned long iova, > > pent = kzalloc(LV2TABLE_SIZE, GFP_ATOMIC); > > BUG_ON((unsigned long)pent & (LV2TABLE_SIZE - 1)); > > if (!pent) > > - return NULL; > > + return ERR_PTR(-ENOMEM); > > > > *sent = mk_lv1ent_page(__pa(pent)); > > *pgcounter = NUM_LV2ENTRIES; > > pgtable_flush(pent, pent + NUM_LV2ENTRIES); > > pgtable_flush(sent, sent + 1); > > + } else if (lv1ent_section(sent)) { > > + return ERR_PTR(-EADDRINUSE); > > } > > > > return page_entry(sent, iova); > > @@ -894,6 +896,12 @@ static int lv1set_section(unsigned long *sent, phys_addr_t paddr, short *pgcnt) > > return 0; > > } > > > > +static void clear_page_table(unsigned long *ent, int n) > > +{ > > + if (n > 0) > > + memset(ent, 0, sizeof(*ent) * n); > > +} > > + > > static int lv2set_page(unsigned long *pent, phys_addr_t paddr, size_t size, > > short *pgcnt) > > { > > @@ -908,7 +916,7 @@ static int lv2set_page(unsigned long *pent, phys_addr_t paddr, size_t size, > > int i; > > for (i = 0; i < SPAGES_PER_LPAGE; i++, pent++) { > > if (!lv2ent_fault(pent)) { > > - memset(pent, 0, sizeof(*pent) * i); > > + clear_page_table(pent - i, i); > > return -EADDRINUSE; > > I am wondering about two issues with this error handling: > 1) we don't call pgtable_flush() in this case - I think just for > consistency we should - don't rush to add since my next comment is to > change this error handling completely. > clear_page_table() is called for the page table entries that are already fault pages. That is why it does not contain cache flush. > 2) If -EADDRINUSE is correct, why does the code clear the IO Page > table entries? > > I think this error path should either > (a) BUG_ON (ie panic) since this is an inconsistency between > generic IOMMU page allocation and chip specific IOMMU mapping code OR > (b) WARN_ON, not clear the entries, and hope whoever was using it > can finish using the system before crashing or gracefully shutting > down. > > In any case, I'm pretty sure this code needs to change and it should > be in a follow up to this series. Yes, you're right. But I worried the case that a kernel module calls IOMMU API functions directly and does not want to make kernel panic when it tries to map a region that is already in use. I also wonder if the such kernel module exists. WARN_ON is also a good idea. Thank you. > > thanks, > grant > > > } > > > > @@ -944,17 +952,16 @@ static int exynos_iommu_map(struct iommu_domain *domain, unsigned long iova, > > pent = alloc_lv2entry(entry, iova, > > &priv->lv2entcnt[lv1ent_offset(iova)]); > > > > - if (!pent) > > - ret = -ENOMEM; > > + if (IS_ERR(pent)) > > + ret = PTR_ERR(pent); > > else > > ret = lv2set_page(pent, paddr, size, > > &priv->lv2entcnt[lv1ent_offset(iova)]); > > } > > > > - if (ret) { > > - pr_debug("%s: Failed to map iova 0x%lx/0x%x bytes\n", > > - __func__, iova, size); > > - } > > + if (ret) > > + pr_err("%s: Failed(%d) to map 0x%#x bytes @ %#lx\n", > > + __func__, ret, size, iova); > > > > spin_unlock_irqrestore(&priv->pgtablelock, flags); > > > > @@ -968,6 +975,7 @@ static size_t exynos_iommu_unmap(struct iommu_domain *domain, > > struct sysmmu_drvdata *data; > > unsigned long flags; > > unsigned long *ent; > > + size_t err_pgsize; > > > > BUG_ON(priv->pgtable == NULL); > > > > @@ -976,7 +984,10 @@ static size_t exynos_iommu_unmap(struct iommu_domain *domain, > > ent = section_entry(priv->pgtable, iova); > > > > if (lv1ent_section(ent)) { > > - BUG_ON(size < SECT_SIZE); > > + if (WARN_ON(size < SECT_SIZE)) { > > + err_pgsize = SECT_SIZE; > > + goto err; > > + } > > > > *ent = 0; > > pgtable_flush(ent, ent + 1); > > @@ -1008,9 +1019,12 @@ static size_t exynos_iommu_unmap(struct iommu_domain *domain, > > } > > > > /* lv1ent_large(ent) == true here */ > > - BUG_ON(size < LPAGE_SIZE); > > + if (WARN_ON(size < LPAGE_SIZE)) { > > + err_pgsize = LPAGE_SIZE; > > + goto err; > > + } > > > > - memset(ent, 0, sizeof(*ent) * SPAGES_PER_LPAGE); > > + clear_page_table(ent, SPAGES_PER_LPAGE); > > pgtable_flush(ent, ent + SPAGES_PER_LPAGE); > > > > size = LPAGE_SIZE; > > @@ -1023,8 +1037,16 @@ done: > > sysmmu_tlb_invalidate_entry(data->dev, iova); > > spin_unlock_irqrestore(&priv->lock, flags); > > > > - > > return size; > > +err: > > + spin_unlock_irqrestore(&priv->pgtablelock, flags); > > + > > + pr_err("%s: Failed due to size(%#x) @ %#lx is"\ > > + " smaller than page size %#x\n", > > + __func__, size, iova, err_pgsize); > > + > > + return 0; > > + > > } > > > > static phys_addr_t exynos_iommu_iova_to_phys(struct iommu_domain *domain, > > -- > > 1.7.2.5 > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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