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asm-generic/tlb: Provide generic tlb_flush() based on flush_tlb_mm()

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When an architecture does not have (an efficient) flush_tlb_range(),
but instead always uses full TLB invalidates, the current generic
tlb_flush() is sub-optimal, for it will generate extra flushes in
order to keep the range small.

But if we cannot do range flushes, that is a moot concern. Optionally
provide this simplified default.

No change in behavior intended.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2018-10-11 16:51:51 +02:00 committed by Ingo Molnar
parent 5f307be18b
commit a30e32bd79
1 changed files with 40 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

41
include/asm-generic/tlb.h
View file

@ -114,7 +114,8 @@
* returns the smallest TLB entry size unmapped in this range.
*
* If an architecture does not provide tlb_flush() a default implementation
* based on flush_tlb_range() will be used.
* based on flush_tlb_range() will be used, unless MMU_GATHER_NO_RANGE is
* specified, in which case we'll default to flush_tlb_mm().
*
* Additionally there are a few opt-in features:
*
@ -140,6 +141,9 @@
* the page-table pages. Required if you use HAVE_RCU_TABLE_FREE and your
* architecture uses the Linux page-tables natively.
*
* MMU_GATHER_NO_RANGE
*
* Use this if your architecture lacks an efficient flush_tlb_range().
*/
#define HAVE_GENERIC_MMU_GATHER
@ -302,12 +306,45 @@ static inline void __tlb_reset_range(struct mmu_gather *tlb)
*/
}
#ifdef CONFIG_MMU_GATHER_NO_RANGE
#if defined(tlb_flush) || defined(tlb_start_vma) || defined(tlb_end_vma)
#error MMU_GATHER_NO_RANGE relies on default tlb_flush(), tlb_start_vma() and tlb_end_vma()
#endif
/*
* When an architecture does not have efficient means of range flushing TLBs
* there is no point in doing intermediate flushes on tlb_end_vma() to keep the
* range small. We equally don't have to worry about page granularity or other
* things.
*
* All we need to do is issue a full flush for any !0 range.
*/
static inline void tlb_flush(struct mmu_gather *tlb)
{
if (tlb->end)
flush_tlb_mm(tlb->mm);
}
static inline void
tlb_update_vma_flags(struct mmu_gather *tlb, struct vm_area_struct *vma) { }
#define tlb_end_vma tlb_end_vma
static inline void tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) { }
#else /* CONFIG_MMU_GATHER_NO_RANGE */
#ifndef tlb_flush
#if defined(tlb_start_vma) || defined(tlb_end_vma)
#error Default tlb_flush() relies on default tlb_start_vma() and tlb_end_vma()
#endif
/*
* When an architecture does not provide its own tlb_flush() implementation
* but does have a reasonably efficient flush_vma_range() implementation
* use that.
*/
static inline void tlb_flush(struct mmu_gather *tlb)
{
if (tlb->fullmm || tlb->need_flush_all) {
@ -348,6 +385,8 @@ tlb_update_vma_flags(struct mmu_gather *tlb, struct vm_area_struct *vma) { }
#endif
#endif /* CONFIG_MMU_GATHER_NO_RANGE */
static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
{
if (!tlb->end)