Commit 594ab90f authored by Robin Murphy's avatar Robin Murphy Committed by Will Deacon
Browse files

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: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 67f3e53d

drivers/iommu/io-pgtable-arm.c

+20 −25
Original line number Diff line number Diff line
@@ -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)	({						\

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