[RFC PATCH 4/5] powerpc/mm/slice: Use const pointers to cached slice masks where possible
Nicholas Piggin
npiggin at gmail.com
Sat Feb 10 19:11:38 AEDT 2018
The slice_mask cache was a basic conversion which copied the slice
mask into caller's structures, because that's how the original code
worked. In most cases the pointer can be used directly instead, saving
a copy and an on-stack structure.
This also converts the slice_mask bit operation helpers to be the usual
3-operand kind, which is clearer to work with. And we remove some
unnecessary intermediate bitmaps, reducing stack and copy overhead
further.
Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
arch/powerpc/mm/slice.c | 78 ++++++++++++++++++++++++++++---------------------
1 file changed, 44 insertions(+), 34 deletions(-)
diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index 98497c105d7d..b2e6c7667bc5 100644
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -430,25 +430,28 @@ static unsigned long slice_find_area(struct mm_struct *mm, unsigned long len,
return slice_find_area_bottomup(mm, len, mask, psize, high_limit);
}
-static inline void slice_or_mask(struct slice_mask *dst,
+static inline void slice_copy_mask(struct slice_mask *dst,
const struct slice_mask *src)
{
- DECLARE_BITMAP(result, SLICE_NUM_HIGH);
+ dst->low_slices = src->low_slices;
+ bitmap_copy(dst->high_slices, src->high_slices, SLICE_NUM_HIGH);
+}
- dst->low_slices |= src->low_slices;
- bitmap_or(result, dst->high_slices, src->high_slices, SLICE_NUM_HIGH);
- bitmap_copy(dst->high_slices, result, SLICE_NUM_HIGH);
+static inline void slice_or_mask(struct slice_mask *dst,
+ const struct slice_mask *src1,
+ const struct slice_mask *src2)
+{
+ dst->low_slices = src1->low_slices | src2->low_slices;
+ bitmap_or(dst->high_slices, src1->high_slices, src2->high_slices, SLICE_NUM_HIGH);
}
static inline void slice_andnot_mask(struct slice_mask *dst,
- const struct slice_mask *src)
+ const struct slice_mask *src1,
+ const struct slice_mask *src2)
{
- DECLARE_BITMAP(result, SLICE_NUM_HIGH);
-
- dst->low_slices &= ~src->low_slices;
+ dst->low_slices = src1->low_slices & ~src2->low_slices;
- bitmap_andnot(result, dst->high_slices, src->high_slices, SLICE_NUM_HIGH);
- bitmap_copy(dst->high_slices, result, SLICE_NUM_HIGH);
+ bitmap_andnot(dst->high_slices, src1->high_slices, src2->high_slices, SLICE_NUM_HIGH);
}
#ifdef CONFIG_PPC_64K_PAGES
@@ -461,10 +464,10 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
unsigned long flags, unsigned int psize,
int topdown)
{
- struct slice_mask mask;
struct slice_mask good_mask;
struct slice_mask potential_mask;
- struct slice_mask compat_mask;
+ const struct slice_mask *maskp;
+ const struct slice_mask *compat_maskp = NULL;
int fixed = (flags & MAP_FIXED);
int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
unsigned long page_size = 1UL << pshift;
@@ -503,9 +506,6 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
potential_mask.low_slices = 0;
bitmap_zero(potential_mask.high_slices, SLICE_NUM_HIGH);
- compat_mask.low_slices = 0;
- bitmap_zero(compat_mask.high_slices, SLICE_NUM_HIGH);
-
/* Sanity checks */
BUG_ON(mm->task_size == 0);
BUG_ON(mm->context.slb_addr_limit == 0);
@@ -528,7 +528,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
/* First make up a "good" mask of slices that have the right size
* already
*/
- good_mask = *slice_mask_for_size(mm, psize);
+ maskp = slice_mask_for_size(mm, psize);
slice_print_mask(" good_mask", &good_mask);
/*
@@ -553,11 +553,16 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
#ifdef CONFIG_PPC_64K_PAGES
/* If we support combo pages, we can allow 64k pages in 4k slices */
if (psize == MMU_PAGE_64K) {
- compat_mask = *slice_mask_for_size(mm, MMU_PAGE_4K);
+ compat_maskp = slice_mask_for_size(mm, MMU_PAGE_4K);
if (fixed)
- slice_or_mask(&good_mask, &compat_mask);
- }
+ slice_or_mask(&good_mask, maskp, compat_maskp);
+ else
+ slice_copy_mask(&good_mask, maskp);
+ } else
#endif
+ {
+ slice_copy_mask(&good_mask, maskp);
+ }
/* First check hint if it's valid or if we have MAP_FIXED */
if (addr || fixed) {
@@ -587,7 +592,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
* empty and thus can be converted
*/
slice_mask_for_free(mm, &potential_mask, high_limit);
- slice_or_mask(&potential_mask, &good_mask);
+ slice_or_mask(&potential_mask, &potential_mask, &good_mask);
slice_print_mask(" potential", &potential_mask);
if (addr || fixed) {
@@ -624,7 +629,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
#ifdef CONFIG_PPC_64K_PAGES
if (addr == -ENOMEM && psize == MMU_PAGE_64K) {
/* retry the search with 4k-page slices included */
- slice_or_mask(&potential_mask, &compat_mask);
+ slice_or_mask(&potential_mask, &potential_mask, compat_maskp);
addr = slice_find_area(mm, len, &potential_mask,
psize, topdown, high_limit);
}
@@ -633,15 +638,17 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
if (addr == -ENOMEM)
return -ENOMEM;
- slice_range_to_mask(addr, len, &mask);
+ slice_range_to_mask(addr, len, &potential_mask);
slice_dbg(" found potential area at 0x%lx\n", addr);
- slice_print_mask(" mask", &mask);
+ slice_print_mask(" mask", maskp);
convert:
- slice_andnot_mask(&mask, &good_mask);
- slice_andnot_mask(&mask, &compat_mask);
- if (mask.low_slices || !bitmap_empty(mask.high_slices, SLICE_NUM_HIGH)) {
- slice_convert(mm, &mask, psize);
+ slice_andnot_mask(&potential_mask, &potential_mask, &good_mask);
+ if (compat_maskp && !fixed)
+ slice_andnot_mask(&potential_mask, &potential_mask, compat_maskp);
+ if (potential_mask.low_slices ||
+ !bitmap_empty(potential_mask.high_slices, SLICE_NUM_HIGH)) {
+ slice_convert(mm, &potential_mask, psize);
if (psize > MMU_PAGE_BASE)
on_each_cpu(slice_flush_segments, mm, 1);
}
@@ -799,19 +806,22 @@ void slice_set_range_psize(struct mm_struct *mm, unsigned long start,
int is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
unsigned long len)
{
- struct slice_mask available;
+ const struct slice_mask *maskp;
unsigned int psize = mm->context.user_psize;
if (radix_enabled())
return 0;
- available = *slice_mask_for_size(mm, psize);
+ maskp = slice_mask_for_size(mm, psize);
#ifdef CONFIG_PPC_64K_PAGES
/* We need to account for 4k slices too */
if (psize == MMU_PAGE_64K) {
- struct slice_mask compat_mask;
- compat_mask = *slice_mask_for_size(mm, MMU_PAGE_4K);
- slice_or_mask(&available, &compat_mask);
+ const struct slice_mask *compat_maskp;
+ struct slice_mask available;
+
+ compat_maskp = slice_mask_for_size(mm, MMU_PAGE_4K);
+ slice_or_mask(&available, maskp, compat_maskp);
+ return !slice_check_range_fits(mm, &available, addr, len);
}
#endif
@@ -821,6 +831,6 @@ int is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
slice_print_mask(" mask", &mask);
slice_print_mask(" available", &available);
#endif
- return !slice_check_range_fits(mm, &available, addr, len);
+ return !slice_check_range_fits(mm, maskp, addr, len);
}
#endif
--
2.15.1
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