linux-kernel - [PATCH 3/4] mmu_gather: Let there be one tlb_{start,end}

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Date:   Fri, 08 Jul 2022 09:18:05 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Jann Horn <jannh@...gle.com>,
        Linus Torvalds <torvalds@...uxfoundation.org>,
        Will Deacon <will@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        peterz@...radead.org, Dave Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Guo Ren <guoren@...nel.org>, David Miller <davem@...emloft.net>
Subject: [PATCH 3/4] mmu_gather: Let there be one tlb_{start,end}_vma() implementation

Now that architectures are no longer allowed to override
tlb_{start,end}_vma() re-arrange code so that there is only one
implementation for each of these functions.

This much simplifies trying to figure out what they actually do.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 include/asm-generic/tlb.h |   15 ++-------------
 1 file changed, 2 insertions(+), 13 deletions(-)

--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -346,8 +346,8 @@ static inline void __tlb_reset_range(str
 
 #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()
+#if defined(tlb_flush)
+#error MMU_GATHER_NO_RANGE relies on default tlb_flush()
 #endif
 
 /*
@@ -367,17 +367,10 @@ static inline void tlb_flush(struct mmu_
 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
@@ -498,7 +491,6 @@ static inline unsigned long tlb_get_unma
  * 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
 static inline void tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
 {
 	if (tlb->fullmm)
@@ -509,9 +501,7 @@ static inline void tlb_start_vma(struct
 	flush_cache_range(vma, vma->vm_start, vma->vm_end);
 #endif
 }
-#endif
 
-#ifndef tlb_end_vma
 static inline void tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
 {
 	if (tlb->fullmm || IS_ENABLED(CONFIG_MMU_GATHER_MERGE_VMAS))
@@ -525,7 +515,6 @@ static inline void tlb_end_vma(struct mm
 	 */
 	tlb_flush_mmu_tlbonly(tlb);
 }
-#endif
 
 /*
  * tlb_flush_{pte|pmd|pud|p4d}_range() adjust the tlb->start and tlb->end,