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Subject[PATCH 5/7] Add freed_tables argument to flush_tlb_mm_range
Date
Add an argument to flush_tlb_mm_range to indicate whether page tables
are about to be freed after this TLB flush. This allows for an
optimization of flush_tlb_mm_range to skip CPUs in lazy TLB mode.

No functional changes.

Signed-off-by: Rik van Riel <riel@surriel.com>
---
arch/x86/include/asm/tlb.h | 6 ++++--
arch/x86/include/asm/tlbflush.h | 12 ++++++++----
arch/x86/kernel/ldt.c | 2 +-
arch/x86/kernel/vm86_32.c | 2 +-
arch/x86/mm/tlb.c | 3 ++-
5 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/tlb.h b/arch/x86/include/asm/tlb.h
index cb0a1f470980..b9237a1f567f 100644
--- a/arch/x86/include/asm/tlb.h
+++ b/arch/x86/include/asm/tlb.h
@@ -9,9 +9,11 @@
#define tlb_flush(tlb) \
{ \
if (!tlb->fullmm && !tlb->need_flush_all) \
- flush_tlb_mm_range(tlb->mm, tlb->start, tlb->end, 0UL); \
+ flush_tlb_mm_range(tlb->mm, tlb->start, tlb->end, 0UL, \
+ tlb->freed_tables); \
else \
- flush_tlb_mm_range(tlb->mm, 0UL, TLB_FLUSH_ALL, 0UL); \
+ flush_tlb_mm_range(tlb->mm, 0UL, TLB_FLUSH_ALL, 0UL, \
+ tlb->freed_tables); \
}

#include <asm-generic/tlb.h>
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 82898cd3d933..ae1ef755cb94 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -515,19 +515,23 @@ struct flush_tlb_info {

#define local_flush_tlb() __flush_tlb()

-#define flush_tlb_mm(mm) flush_tlb_mm_range(mm, 0UL, TLB_FLUSH_ALL, 0UL)
+/* Simultaneous unmap operations could have freed page tables. */
+#define flush_tlb_mm(mm) \
+ flush_tlb_mm_range(mm, 0UL, TLB_FLUSH_ALL, 0UL, true)

+/* The operations calling flush_tlb_range do not free page tables. */
#define flush_tlb_range(vma, start, end) \
- flush_tlb_mm_range(vma->vm_mm, start, end, vma->vm_flags)
+ flush_tlb_mm_range(vma->vm_mm, start, end, vma->vm_flags, false)

extern void flush_tlb_all(void);
extern void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
- unsigned long end, unsigned long vmflag);
+ unsigned long end, unsigned long vmflag,
+ bool freed_tables);
extern void flush_tlb_kernel_range(unsigned long start, unsigned long end);

static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long a)
{
- flush_tlb_mm_range(vma->vm_mm, a, a + PAGE_SIZE, VM_NONE);
+ flush_tlb_mm_range(vma->vm_mm, a, a + PAGE_SIZE, VM_NONE, false);
}

void native_flush_tlb_others(const struct cpumask *cpumask,
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index 26d713ecad34..2c2291fa14b3 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -190,7 +190,7 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
}

va = (unsigned long)ldt_slot_va(slot);
- flush_tlb_mm_range(mm, va, va + LDT_SLOT_STRIDE, 0);
+ flush_tlb_mm_range(mm, va, va + LDT_SLOT_STRIDE, 0, false);

ldt->slot = slot;
#endif
diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 5edb27f1a2c4..51024424dfbe 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -199,7 +199,7 @@ static void mark_screen_rdonly(struct mm_struct *mm)
pte_unmap_unlock(pte, ptl);
out:
up_write(&mm->mmap_sem);
- flush_tlb_mm_range(mm, 0xA0000, 0xA0000 + 32*PAGE_SIZE, 0UL);
+ flush_tlb_mm_range(mm, 0xA0000, 0xA0000 + 32*PAGE_SIZE, 0UL, false);
}


diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index ac05d61cc90e..62f147b0f6b7 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -571,7 +571,8 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
static unsigned long tlb_single_page_flush_ceiling __read_mostly = 33;

void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
- unsigned long end, unsigned long vmflag)
+ unsigned long end, unsigned long vmflag,
+ bool freed_tables)
{
int cpu;

--
2.17.1
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