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authorWill Deacon <will.deacon@arm.com>2018-08-23 21:01:46 +0100
committerWill Deacon <will.deacon@arm.com>2018-09-04 11:08:27 +0100
commita6d60245d6d9b1caf66b0d94419988c4836980af (patch)
tree7c09c92c42b987a72d5c1c2410cd0918d2c76c17 /include/asm-generic/tlb.h
parent22a61c3c4f1379ef8b0ce0d5cb78baf3178950e2 (diff)
downloadlwn-a6d60245d6d9b1caf66b0d94419988c4836980af.tar.gz
lwn-a6d60245d6d9b1caf66b0d94419988c4836980af.zip
asm-generic/tlb: Track which levels of the page tables have been cleared
It is common for architectures with hugepage support to require only a single TLB invalidation operation per hugepage during unmap(), rather than iterating through the mapping at a PAGE_SIZE increment. Currently, however, the level in the page table where the unmap() operation occurs is not stored in the mmu_gather structure, therefore forcing architectures to issue additional TLB invalidation operations or to give up and over-invalidate by e.g. invalidating the entire TLB. Ideally, we could add an interval rbtree to the mmu_gather structure, which would allow us to associate the correct mapping granule with the various sub-mappings within the range being invalidated. However, this is costly in terms of book-keeping and memory management, so instead we approximate by keeping track of the page table levels that are cleared and provide a means to query the smallest granule required for invalidation. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'include/asm-generic/tlb.h')
-rw-r--r--include/asm-generic/tlb.h58
1 files changed, 50 insertions, 8 deletions
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 2b444ad94566..9791e98122a0 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -116,6 +116,14 @@ struct mmu_gather {
*/
unsigned int freed_tables : 1;
+ /*
+ * at which levels have we cleared entries?
+ */
+ unsigned int cleared_ptes : 1;
+ unsigned int cleared_pmds : 1;
+ unsigned int cleared_puds : 1;
+ unsigned int cleared_p4ds : 1;
+
struct mmu_gather_batch *active;
struct mmu_gather_batch local;
struct page *__pages[MMU_GATHER_BUNDLE];
@@ -150,6 +158,10 @@ static inline void __tlb_reset_range(struct mmu_gather *tlb)
tlb->end = 0;
}
tlb->freed_tables = 0;
+ tlb->cleared_ptes = 0;
+ tlb->cleared_pmds = 0;
+ tlb->cleared_puds = 0;
+ tlb->cleared_p4ds = 0;
}
static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
@@ -199,6 +211,25 @@ static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
}
#endif
+static inline unsigned long tlb_get_unmap_shift(struct mmu_gather *tlb)
+{
+ if (tlb->cleared_ptes)
+ return PAGE_SHIFT;
+ if (tlb->cleared_pmds)
+ return PMD_SHIFT;
+ if (tlb->cleared_puds)
+ return PUD_SHIFT;
+ if (tlb->cleared_p4ds)
+ return P4D_SHIFT;
+
+ return PAGE_SHIFT;
+}
+
+static inline unsigned long tlb_get_unmap_size(struct mmu_gather *tlb)
+{
+ return 1UL << tlb_get_unmap_shift(tlb);
+}
+
/*
* In the case of tlb vma handling, we can optimise these away in the
* case where we're doing a full MM flush. When we're doing a munmap,
@@ -232,13 +263,19 @@ static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
#define tlb_remove_tlb_entry(tlb, ptep, address) \
do { \
__tlb_adjust_range(tlb, address, PAGE_SIZE); \
+ tlb->cleared_ptes = 1; \
__tlb_remove_tlb_entry(tlb, ptep, address); \
} while (0)
-#define tlb_remove_huge_tlb_entry(h, tlb, ptep, address) \
- do { \
- __tlb_adjust_range(tlb, address, huge_page_size(h)); \
- __tlb_remove_tlb_entry(tlb, ptep, address); \
+#define tlb_remove_huge_tlb_entry(h, tlb, ptep, address) \
+ do { \
+ unsigned long _sz = huge_page_size(h); \
+ __tlb_adjust_range(tlb, address, _sz); \
+ if (_sz == PMD_SIZE) \
+ tlb->cleared_pmds = 1; \
+ else if (_sz == PUD_SIZE) \
+ tlb->cleared_puds = 1; \
+ __tlb_remove_tlb_entry(tlb, ptep, address); \
} while (0)
/**
@@ -252,6 +289,7 @@ static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
#define tlb_remove_pmd_tlb_entry(tlb, pmdp, address) \
do { \
__tlb_adjust_range(tlb, address, HPAGE_PMD_SIZE); \
+ tlb->cleared_pmds = 1; \
__tlb_remove_pmd_tlb_entry(tlb, pmdp, address); \
} while (0)
@@ -266,6 +304,7 @@ static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
#define tlb_remove_pud_tlb_entry(tlb, pudp, address) \
do { \
__tlb_adjust_range(tlb, address, HPAGE_PUD_SIZE); \
+ tlb->cleared_puds = 1; \
__tlb_remove_pud_tlb_entry(tlb, pudp, address); \
} while (0)
@@ -291,7 +330,8 @@ static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
#define pte_free_tlb(tlb, ptep, address) \
do { \
__tlb_adjust_range(tlb, address, PAGE_SIZE); \
- tlb->freed_tables = 1; \
+ tlb->freed_tables = 1; \
+ tlb->cleared_pmds = 1; \
__pte_free_tlb(tlb, ptep, address); \
} while (0)
#endif
@@ -300,7 +340,8 @@ static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
#define pmd_free_tlb(tlb, pmdp, address) \
do { \
__tlb_adjust_range(tlb, address, PAGE_SIZE); \
- tlb->freed_tables = 1; \
+ tlb->freed_tables = 1; \
+ tlb->cleared_puds = 1; \
__pmd_free_tlb(tlb, pmdp, address); \
} while (0)
#endif
@@ -310,7 +351,8 @@ static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
#define pud_free_tlb(tlb, pudp, address) \
do { \
__tlb_adjust_range(tlb, address, PAGE_SIZE); \
- tlb->freed_tables = 1; \
+ tlb->freed_tables = 1; \
+ tlb->cleared_p4ds = 1; \
__pud_free_tlb(tlb, pudp, address); \
} while (0)
#endif
@@ -321,7 +363,7 @@ static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
#define p4d_free_tlb(tlb, pudp, address) \
do { \
__tlb_adjust_range(tlb, address, PAGE_SIZE); \
- tlb->freed_tables = 1; \
+ tlb->freed_tables = 1; \
__p4d_free_tlb(tlb, pudp, address); \
} while (0)
#endif