From: Will Deacon <will.deacon@xxxxxxx>
[ Upstream commit fb7332a9fedfd62b1ba6530c86f39f0fa38afd49 ]
On architectures with hardware broadcasting of TLB invalidation messages
, it makes sense to reduce the range of the mmu_gather structure when
unmapping page ranges based on the dirty address information passed to
tlb_remove_tlb_entry.
arm64 already does this by directly manipulating the start/end fields
of the gather structure, but this confuses the generic code which
does not expect these fields to change and can end up calculating
invalid, negative ranges when forcing a flush in zap_pte_range.
This patch moves the minimal range calculation out of the arm64 code
and into the generic implementation, simplifying zap_pte_range in the
process (which no longer needs to care about start/end, since they will
point to the appropriate ranges already). With the range being tracked
by core code, the need_flush flag is dropped in favour of checking that
the end of the range has actually been set.
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>
Cc: Michal Simek <monstr@xxxxxxxxx>
Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
arch/arm64/include/asm/tlb.h | 67 ++------------------------------------
arch/microblaze/include/asm/tlb.h | 3 +-
arch/powerpc/include/asm/pgalloc.h | 3 +-
arch/powerpc/include/asm/tlb.h | 1 +
arch/powerpc/mm/hugetlbpage.c | 2 --
include/asm-generic/tlb.h | 57 ++++++++++++++++++++++++++------
mm/memory.c | 30 +++++------------
7 files changed, 63 insertions(+), 100 deletions(-)
diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
index a82c0c5..c028fe3 100644
--- a/arch/arm64/include/asm/tlb.h
+++ b/arch/arm64/include/asm/tlb.h
@@ -19,10 +19,6 @@
#ifndef __ASM_TLB_H
#define __ASM_TLB_H
-#define __tlb_remove_pmd_tlb_entry __tlb_remove_pmd_tlb_entry
-
-#include <asm-generic/tlb.h>
-
#include <linux/pagemap.h>
#include <linux/swap.h>
@@ -37,71 +33,22 @@ static inline void __tlb_remove_table(void *_table)
#define tlb_remove_entry(tlb, entry) tlb_remove_page(tlb, entry)
#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
-/*
- * There's three ways the TLB shootdown code is used:
- * 1. Unmapping a range of vmas. See zap_page_range(), unmap_region().
- * tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called.
- * 2. Unmapping all vmas. See exit_mmap().
- * tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called.
- * Page tables will be freed.
- * 3. Unmapping argument pages. See shift_arg_pages().
- * tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called.
- */
+#include <asm-generic/tlb.h>
+
static inline void tlb_flush(struct mmu_gather *tlb)
{
if (tlb->fullmm) {
flush_tlb_mm(tlb->mm);
- } else if (tlb->end > 0) {
+ } else {
struct vm_area_struct vma = { .vm_mm = tlb->mm, };
flush_tlb_range(&vma, tlb->start, tlb->end);
- tlb->start = TASK_SIZE;
- tlb->end = 0;
- }
-}
-
-static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
-{
- if (!tlb->fullmm) {
- tlb->start = min(tlb->start, addr);
- tlb->end = max(tlb->end, addr + PAGE_SIZE);
- }
-}
-
-/*
- * Memorize the range for the TLB flush.
- */
-static inline void __tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep,
- unsigned long addr)
-{
- tlb_add_flush(tlb, addr);
-}
-
-/*
- * 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,
- * the vmas are adjusted to only cover the region to be torn down.
- */
-static inline void tlb_start_vma(struct mmu_gather *tlb,
- struct vm_area_struct *vma)
-{
- if (!tlb->fullmm) {
- tlb->start = TASK_SIZE;
- tlb->end = 0;
}
}
-static inline void tlb_end_vma(struct mmu_gather *tlb,
- struct vm_area_struct *vma)
-{
- if (!tlb->fullmm)
- tlb_flush(tlb);
-}
-
static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
unsigned long addr)
{
pgtable_page_dtor(pte);
- tlb_add_flush(tlb, addr);
tlb_remove_entry(tlb, pte);
}
@@ -109,7 +56,6 @@ static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
unsigned long addr)
{
- tlb_add_flush(tlb, addr);
tlb_remove_entry(tlb, virt_to_page(pmdp));
}
#endif
@@ -118,15 +64,8 @@ static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pudp,
unsigned long addr)
{
- tlb_add_flush(tlb, addr);
tlb_remove_entry(tlb, virt_to_page(pudp));
}
#endif
-static inline void __tlb_remove_pmd_tlb_entry(struct mmu_gather *tlb, pmd_t *pmdp,
- unsigned long address)
-{
- tlb_add_flush(tlb, address);
-}
-
#endif
diff --git a/arch/microblaze/include/asm/tlb.h b/arch/microblaze/include/asm/tlb.h
index 8aa9781..99b6ded 100644
--- a/arch/microblaze/include/asm/tlb.h
+++ b/arch/microblaze/include/asm/tlb.h
@@ -14,7 +14,6 @@
#define tlb_flush(tlb) flush_tlb_mm((tlb)->mm)
#include <linux/pagemap.h>
-#include <asm-generic/tlb.h>
#ifdef CONFIG_MMU
#define tlb_start_vma(tlb, vma) do { } while (0)
@@ -22,4 +21,6 @@
#define __tlb_remove_tlb_entry(tlb, pte, address) do { } while (0)
#endif
+#include <asm-generic/tlb.h>
+
#endif /* _ASM_MICROBLAZE_TLB_H */
diff --git a/arch/powerpc/include/asm/pgalloc.h b/arch/powerpc/include/asm/pgalloc.h
index e9a9f60..fc3ee06 100644
--- a/arch/powerpc/include/asm/pgalloc.h
+++ b/arch/powerpc/include/asm/pgalloc.h
@@ -3,7 +3,6 @@
#ifdef __KERNEL__
#include <linux/mm.h>
-#include <asm-generic/tlb.h>
#ifdef CONFIG_PPC_BOOK3E
extern void tlb_flush_pgtable(struct mmu_gather *tlb, unsigned long address);
@@ -14,6 +13,8 @@ static inline void tlb_flush_pgtable(struct mmu_gather *tlb,
}
#endif /* !CONFIG_PPC_BOOK3E */
+extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
+
#ifdef CONFIG_PPC64
#include <asm/pgalloc-64.h>
#else
diff --git a/arch/powerpc/include/asm/tlb.h b/arch/powerpc/include/asm/tlb.h
index e2b428b..20733fa 100644
--- a/arch/powerpc/include/asm/tlb.h
+++ b/arch/powerpc/include/asm/tlb.h
@@ -27,6 +27,7 @@
#define tlb_start_vma(tlb, vma) do { } while (0)
#define tlb_end_vma(tlb, vma) do { } while (0)
+#define __tlb_remove_tlb_entry __tlb_remove_tlb_entry
extern void tlb_flush(struct mmu_gather *tlb);
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 7e70ae9..6a4a5fc 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -517,8 +517,6 @@ static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshif
for (i = 0; i < num_hugepd; i++, hpdp++)
hpdp->pd = 0;
- tlb->need_flush = 1;
-
#ifdef CONFIG_PPC_FSL_BOOK3E
hugepd_free(tlb, hugepte);
#else
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 5672d7e..0884805 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -96,10 +96,9 @@ struct mmu_gather {
#endif
unsigned long start;
unsigned long end;
- unsigned int need_flush : 1, /* Did free PTEs */
/* we are in the middle of an operation to clear
* a full mm and can make some optimizations */
- fullmm : 1,
+ unsigned int fullmm : 1,
/* we have performed an operation which
* requires a complete flush of the tlb */
need_flush_all : 1;
@@ -128,16 +127,54 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
tlb_flush_mmu(tlb);
}
+static inline void __tlb_adjust_range(struct mmu_gather *tlb,
+ unsigned long address)
+{
+ tlb->start = min(tlb->start, address);
+ tlb->end = max(tlb->end, address + PAGE_SIZE);
+}
+
+static inline void __tlb_reset_range(struct mmu_gather *tlb)
+{
+ tlb->start = TASK_SIZE;
+ tlb->end = 0;
+}
+
+/*
+ * 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,
+ * the vmas are adjusted to only cover the region to be torn down.
+ */
+#ifndef tlb_start_vma
+#define tlb_start_vma(tlb, vma) do { } while (0)
+#endif
+
+#define __tlb_end_vma(tlb, vma) \
+ do { \
+ if (!tlb->fullmm && tlb->end) { \
+ tlb_flush(tlb); \
+ __tlb_reset_range(tlb); \
+ } \
+ } while (0)
+
+#ifndef tlb_end_vma
+#define tlb_end_vma __tlb_end_vma
+#endif
+
+#ifndef __tlb_remove_tlb_entry
+#define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0)
+#endif
+
/**
* tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
*
- * Record the fact that pte's were really umapped in ->need_flush, so we can
- * later optimise away the tlb invalidate. This helps when userspace is
- * unmapping already-unmapped pages, which happens quite a lot.
+ * Record the fact that pte's were really unmapped by updating the range,
+ * so we can later optimise away the tlb invalidate. This helps when
+ * userspace is unmapping already-unmapped pages, which happens quite a lot.
*/
#define tlb_remove_tlb_entry(tlb, ptep, address) \
do { \
- tlb->need_flush = 1; \
+ __tlb_adjust_range(tlb, address); \
__tlb_remove_tlb_entry(tlb, ptep, address); \
} while (0)
@@ -151,27 +188,27 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
#define tlb_remove_pmd_tlb_entry(tlb, pmdp, address) \
do { \
- tlb->need_flush = 1; \
+ __tlb_adjust_range(tlb, address); \
__tlb_remove_pmd_tlb_entry(tlb, pmdp, address); \
} while (0)
#define pte_free_tlb(tlb, ptep, address) \
do { \
- tlb->need_flush = 1; \
+ __tlb_adjust_range(tlb, address); \
__pte_free_tlb(tlb, ptep, address); \
} while (0)
#ifndef __ARCH_HAS_4LEVEL_HACK
#define pud_free_tlb(tlb, pudp, address) \
do { \
- tlb->need_flush = 1; \
+ __tlb_adjust_range(tlb, address); \
__pud_free_tlb(tlb, pudp, address); \
} while (0)
#endif
#define pmd_free_tlb(tlb, pmdp, address) \
do { \
- tlb->need_flush = 1; \
+ __tlb_adjust_range(tlb, address); \
__pmd_free_tlb(tlb, pmdp, address); \
} while (0)
diff --git a/mm/memory.c b/mm/memory.c
index 4ffa7b5..90fb265 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -220,9 +220,6 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long
/* Is it from 0 to ~0? */
tlb->fullmm = !(start | (end+1));
tlb->need_flush_all = 0;
- tlb->start = start;
- tlb->end = end;
- tlb->need_flush = 0;
tlb->local.next = NULL;
tlb->local.nr = 0;
tlb->local.max = ARRAY_SIZE(tlb->__pages);
@@ -232,15 +229,20 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
tlb->batch = NULL;
#endif
+
+ __tlb_reset_range(tlb);
}
static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
{
- tlb->need_flush = 0;
+ if (!tlb->end)
+ return;
+
tlb_flush(tlb);
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
tlb_table_flush(tlb);
#endif
+ __tlb_reset_range(tlb);
}
static void tlb_flush_mmu_free(struct mmu_gather *tlb)
@@ -256,8 +258,6 @@ static void tlb_flush_mmu_free(struct mmu_gather *tlb)
void tlb_flush_mmu(struct mmu_gather *tlb)
{
- if (!tlb->need_flush)
- return;
tlb_flush_mmu_tlbonly(tlb);
tlb_flush_mmu_free(tlb);
}
@@ -292,7 +292,7 @@ int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
{
struct mmu_gather_batch *batch;
- VM_BUG_ON(!tlb->need_flush);
+ VM_BUG_ON(!tlb->end);
batch = tlb->active;
batch->pages[batch->nr++] = page;
@@ -359,8 +359,6 @@ void tlb_remove_table(struct mmu_gather *tlb, void *table)
{
struct mmu_table_batch **batch = &tlb->batch;
- tlb->need_flush = 1;
-
/*
* When there's less then two users of this mm there cannot be a
* concurrent page-table walk.
@@ -1186,20 +1184,8 @@ again:
arch_leave_lazy_mmu_mode();
/* Do the actual TLB flush before dropping ptl */
- if (force_flush) {
- unsigned long old_end;
-
- /*
- * Flush the TLB just for the previous segment,
- * then update the range to be the remaining
- * TLB range.
- */
- old_end = tlb->end;
- tlb->end = addr;
+ if (force_flush)
tlb_flush_mmu_tlbonly(tlb);
- tlb->start = addr;
- tlb->end = old_end;
- }
pte_unmap_unlock(start_pte, ptl);
/*
--
2.1.0
--
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