Re: [PATCH] iommu: exynos: pointers are nto physical addresses

From: Marek Szyprowski
Date: Mon Feb 29 2016 - 04:34:25 EST


Hi Arnd,

On 2016-02-29 09:45, Arnd Bergmann wrote:
The exynos iommu driver changed an incorrect cast from pointer
to 'unsigned int' to an equally incorrect cast to a 'phys_addr_t',
which results in an obvious compile-time error when phys_addr_t
is wider than pointers are:

drivers/iommu/exynos-iommu.c: In function 'alloc_lv2entry':
drivers/iommu/exynos-iommu.c:918:32: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]

The code does not actually want the physical address (which would
involve using virt_to_phys()), but just checks the alignment,
so we can change it to use a cast to uintptr_t instead.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Fixes: 740a01eee9ad ("iommu/exynos: Add support for v5 SYSMMU")

Thanks for this fix.

---
I also see that some incorrect __raw_writel() calls have crept in
around the same time, which breaks running big-endian kernels when
this driver is loaded.

Please fix and that that as well.

Okay, so in the driver code all __raw_writel should be replaced by
writel(), right?

Those __raw_writel() calls were there from the beginning and I didn't
know that they should not be used in the driver code.

drivers/iommu/exynos-iommu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index b0665042bf29..484b3b37631f 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -915,7 +915,7 @@ static sysmmu_pte_t *alloc_lv2entry(struct exynos_iommu_domain *domain,
bool need_flush_flpd_cache = lv1ent_zero(sent);
pent = kmem_cache_zalloc(lv2table_kmem_cache, GFP_ATOMIC);
- BUG_ON((phys_addr_t)pent & (LV2TABLE_SIZE - 1));
+ BUG_ON((uintptr_t)pent & (LV2TABLE_SIZE - 1));
if (!pent)
return ERR_PTR(-ENOMEM);

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland