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iommu/io-pgtable-arm: Simplify start level lookup 

Beyond a couple of allocation-time calculations, data->levels is only
ever used to derive the start level. Storing the start level directly
leads to a small reduction in object code, which should help eke out a
little more efficiency, and slightly more readable source to boot.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Robin Murphy 2019-10-25 19:08:33 +01:00 committed by Will Deacon
parent 67f3e53d2a
commit 594ab90fc4
1 changed files with 20 additions and 25 deletions
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45
drivers/iommu/io-pgtable-arm.c
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@ -31,19 +31,13 @@
#define io_pgtable_ops_to_data(x) \
io_pgtable_to_data(io_pgtable_ops_to_pgtable(x))
/*
* For consistency with the architecture, we always consider
* ARM_LPAE_MAX_LEVELS levels, with the walk starting at level n >=0
*/
#define ARM_LPAE_START_LVL(d) (ARM_LPAE_MAX_LEVELS - (d)->levels)
/*
* Calculate the right shift amount to get to the portion describing level l
* in a virtual address mapped by the pagetable in d.
*/
#define ARM_LPAE_LVL_SHIFT(l,d) \
((((d)->levels - ((l) - ARM_LPAE_START_LVL(d) + 1)) \
* (d)->bits_per_level) + (d)->pg_shift)
(((ARM_LPAE_MAX_LEVELS - 1 - (l)) * (d)->bits_per_level) + \
(d)->pg_shift)
#define ARM_LPAE_GRANULE(d) (1UL << (d)->pg_shift)
@ -55,7 +49,7 @@
* pagetable in d.
*/
#define ARM_LPAE_PGD_IDX(l,d) \
((l) == ARM_LPAE_START_LVL(d) ? ilog2(ARM_LPAE_PAGES_PER_PGD(d)) : 0)
((l) == (d)->start_level ? ilog2(ARM_LPAE_PAGES_PER_PGD(d)) : 0)
#define ARM_LPAE_LVL_IDX(a,l,d) \
(((u64)(a) >> ARM_LPAE_LVL_SHIFT(l,d)) & \
@ -180,7 +174,7 @@
struct arm_lpae_io_pgtable {
struct io_pgtable iop;
int levels;
int start_level;
size_t pgd_size;
unsigned long pg_shift;
unsigned long bits_per_level;
@ -481,7 +475,7 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
struct io_pgtable_cfg *cfg = &data->iop.cfg;
arm_lpae_iopte *ptep = data->pgd;
int ret, lvl = ARM_LPAE_START_LVL(data);
int ret, lvl = data->start_level;
arm_lpae_iopte prot;
/* If no access, then nothing to do */
@ -511,7 +505,7 @@ static void __arm_lpae_free_pgtable(struct arm_lpae_io_pgtable *data, int lvl,
arm_lpae_iopte *start, *end;
unsigned long table_size;
if (lvl == ARM_LPAE_START_LVL(data))
if (lvl == data->start_level)
table_size = data->pgd_size;
else
table_size = ARM_LPAE_GRANULE(data);
@ -540,7 +534,7 @@ static void arm_lpae_free_pgtable(struct io_pgtable *iop)
{
struct arm_lpae_io_pgtable *data = io_pgtable_to_data(iop);
__arm_lpae_free_pgtable(data, ARM_LPAE_START_LVL(data), data->pgd);
__arm_lpae_free_pgtable(data, data->start_level, data->pgd);
kfree(data);
}
@ -657,7 +651,6 @@ static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
struct io_pgtable_cfg *cfg = &data->iop.cfg;
arm_lpae_iopte *ptep = data->pgd;
int lvl = ARM_LPAE_START_LVL(data);
if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
return 0;
@ -665,7 +658,7 @@ static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
if (WARN_ON(iova >> data->iop.cfg.ias))
return 0;
return __arm_lpae_unmap(data, gather, iova, size, lvl, ptep);
return __arm_lpae_unmap(data, gather, iova, size, data->start_level, ptep);
}
static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops,
@ -673,7 +666,7 @@ static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops,
{
struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
arm_lpae_iopte pte, *ptep = data->pgd;
int lvl = ARM_LPAE_START_LVL(data);
int lvl = data->start_level;
do {
/* Valid IOPTE pointer? */
@ -752,6 +745,7 @@ arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg)
{
unsigned long va_bits, pgd_bits;
struct arm_lpae_io_pgtable *data;
int levels;
arm_lpae_restrict_pgsizes(cfg);
@ -777,10 +771,11 @@ arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg)
data->bits_per_level = data->pg_shift - ilog2(sizeof(arm_lpae_iopte));
va_bits = cfg->ias - data->pg_shift;
data->levels = DIV_ROUND_UP(va_bits, data->bits_per_level);
levels = DIV_ROUND_UP(va_bits, data->bits_per_level);
data->start_level = ARM_LPAE_MAX_LEVELS - levels;
/* Calculate the actual size of our pgd (without concatenation) */
pgd_bits = va_bits - (data->bits_per_level * (data->levels - 1));
pgd_bits = va_bits - (data->bits_per_level * (levels - 1));
data->pgd_size = 1UL << (pgd_bits + ilog2(sizeof(arm_lpae_iopte)));
data->iop.ops = (struct io_pgtable_ops) {
@ -910,13 +905,13 @@ arm_64_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg, void *cookie)
* Concatenate PGDs at level 1 if possible in order to reduce
* the depth of the stage-2 walk.
*/
if (data->levels == ARM_LPAE_MAX_LEVELS) {
if (data->start_level == 0) {
unsigned long pgd_pages;
pgd_pages = data->pgd_size >> ilog2(sizeof(arm_lpae_iopte));
if (pgd_pages <= ARM_LPAE_S2_MAX_CONCAT_PAGES) {
data->pgd_size = pgd_pages << data->pg_shift;
data->levels--;
data->start_level++;
}
}
@ -926,7 +921,7 @@ arm_64_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg, void *cookie)
(ARM_LPAE_TCR_RGN_WBWA << ARM_LPAE_TCR_IRGN0_SHIFT) |
(ARM_LPAE_TCR_RGN_WBWA << ARM_LPAE_TCR_ORGN0_SHIFT);
sl = ARM_LPAE_START_LVL(data);
sl = data->start_level;
switch (ARM_LPAE_GRANULE(data)) {
case SZ_4K:
@ -1041,8 +1036,8 @@ arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
return NULL;
/* Mali seems to need a full 4-level table regardless of IAS */
if (data->levels < ARM_LPAE_MAX_LEVELS) {
data->levels = ARM_LPAE_MAX_LEVELS;
if (data->start_level > 0) {
data->start_level = 0;
data->pgd_size = sizeof(arm_lpae_iopte);
}
/*
@ -1140,8 +1135,8 @@ static void __init arm_lpae_dump_ops(struct io_pgtable_ops *ops)
pr_err("cfg: pgsize_bitmap 0x%lx, ias %u-bit\n",
cfg->pgsize_bitmap, cfg->ias);
pr_err("data: %d levels, 0x%zx pgd_size, %lu pg_shift, %lu bits_per_level, pgd @ %p\n",
data->levels, data->pgd_size, data->pg_shift,
data->bits_per_level, data->pgd);
ARM_LPAE_MAX_LEVELS - data->start_level, data->pgd_size,
data->pg_shift, data->bits_per_level, data->pgd);
}
#define __FAIL(ops, i) ({ \