On Wed 21-11-18 16:46:38, Will Deacon wrote:

On Sun, Nov 11, 2018 at 05:03:41PM +0800, Nicolas Boichat wrote:

quoted

For level 1/2 pages, ensure GFP_DMA32 is used if CONFIG_ZONE_DMA32
is defined (e.g. on arm64 platforms).

For level 2 pages, allocate a slab cache in SLAB_CACHE_DMA32.

Also, print an error when the physical address does not fit in
32-bit, to make debugging easier in the future.

Fixes: ad67f5a6545f ("arm64: replace ZONE_DMA with ZONE_DMA32")
Signed-off-by: Nicolas Boichat <redacted>
---

Changes since v1:
 - Changed approach to use SLAB_CACHE_DMA32 added by the previous
   commit.
 - Use DMA or DMA32 depending on the architecture (DMA for arm,
   DMA32 for arm64).

drivers/iommu/io-pgtable-arm-v7s.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
index 445c3bde04800c..996f7b6d00b44a 100644
--- a/drivers/iommu/io-pgtable-arm-v7s.c
+++ b/drivers/iommu/io-pgtable-arm-v7s.c

@@ -161,6 +161,14 @@
 
 #define ARM_V7S_TCR_PD1			BIT(5)
 
+#ifdef CONFIG_ZONE_DMA32
+#define ARM_V7S_TABLE_GFP_DMA GFP_DMA32
+#define ARM_V7S_TABLE_SLAB_CACHE SLAB_CACHE_DMA32
+#else
+#define ARM_V7S_TABLE_GFP_DMA GFP_DMA
+#define ARM_V7S_TABLE_SLAB_CACHE SLAB_CACHE_DMA
+#endif

It's a bit grotty that GFP_DMA32 doesn't just map to GFP_DMA on 32-bit
architectures, since then we wouldn't need this #ifdeffery afaict.

But GFP_DMA32 should map to GFP_KERNEL on 32b, no? Or what exactly is
going on in here?

-- 
Michal Hocko
SUSE Labs