iommu/arm-smmu: use page shift instead of page size to avoid division
Arbitrary integer division is not available in all ARM CPUs, so the GCC
may spit out calls to helper functions which are not implemented in
the kernel.
This patch avoids these problems in the SMMU driver by using page shift
instead of page size, so that divisions by the page size (as required
by the vSMMU code) can be expressed as a simple right shift.
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index e8d31115..482cc9e 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -59,7 +59,7 @@
/* SMMU global address space */
#define ARM_SMMU_GR0(smmu) ((smmu)->base)
-#define ARM_SMMU_GR1(smmu) ((smmu)->base + (smmu)->pagesize)
+#define ARM_SMMU_GR1(smmu) ((smmu)->base + (1 << (smmu)->pgshift))
/*
* SMMU global address space with conditional offset to access secure
@@ -224,7 +224,7 @@
/* Translation context bank */
#define ARM_SMMU_CB_BASE(smmu) ((smmu)->base + ((smmu)->size >> 1))
-#define ARM_SMMU_CB(smmu, n) ((n) * (smmu)->pagesize)
+#define ARM_SMMU_CB(smmu, n) ((n) * (1 << (smmu)->pgshift))
#define ARM_SMMU_CB_SCTLR 0x0
#define ARM_SMMU_CB_RESUME 0x8
@@ -354,7 +354,7 @@
void __iomem *base;
unsigned long size;
- unsigned long pagesize;
+ unsigned long pgshift;
#define ARM_SMMU_FEAT_COHERENT_WALK (1 << 0)
#define ARM_SMMU_FEAT_STREAM_MATCH (1 << 1)
@@ -1814,12 +1814,12 @@
/* ID1 */
id = readl_relaxed(gr0_base + ARM_SMMU_GR0_ID1);
- smmu->pagesize = (id & ID1_PAGESIZE) ? SZ_64K : SZ_4K;
+ smmu->pgshift = (id & ID1_PAGESIZE) ? 16 : 12;
/* Check for size mismatch of SMMU address space from mapped region */
size = 1 <<
(((id >> ID1_NUMPAGENDXB_SHIFT) & ID1_NUMPAGENDXB_MASK) + 1);
- size *= (smmu->pagesize << 1);
+ size *= 2 << smmu->pgshift;
if (smmu->size != size)
dev_warn(smmu->dev,
"SMMU address space size (0x%lx) differs from mapped region size (0x%lx)!\n",