linux-kernel - [PATCH 1/3] mm: set page fault address for update_mmu_cache

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Date:   Wed, 24 Jun 2020 17:26:30 +0800
From:   Bibo Mao <maobibo@...ngson.cn>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Paul Burton <paulburton@...nel.org>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Daniel Silsby <dansilsby@...il.com>
Cc:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: [PATCH 1/3] mm: set page fault address for update_mmu_cache_pmd

update_mmu_cache_pmd is used to update tlb for the pmd entry by
software. On MIPS system, the tlb entry indexed by page fault
address maybe exists already, only that tlb entry may be small
page, also it may be huge page. Before updating pmd entry with
huge page size, older tlb entry need to be invalidated.

Here page fault address is passed to function update_mmu_cache_pmd,
rather than pmd huge page start address. The page fault address
can be used for invalidating older tlb entry.

Signed-off-by: Bibo Mao <maobibo@...ngson.cn>
---
 arch/mips/include/asm/pgtable.h | 9 +++++++++
 mm/huge_memory.c                | 7 ++++---
 mm/memory.c                     | 2 +-
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index dd7a0f5..bd81661 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -554,11 +554,20 @@ static inline void update_mmu_cache(struct vm_area_struct *vma,
 #define	__HAVE_ARCH_UPDATE_MMU_TLB
 #define update_mmu_tlb	update_mmu_cache
 
+extern void local_flush_tlb_page(struct vm_area_struct *vma,
+				unsigned long page);
 static inline void update_mmu_cache_pmd(struct vm_area_struct *vma,
 	unsigned long address, pmd_t *pmdp)
 {
 	pte_t pte = *(pte_t *)pmdp;
 
+	/*
+	 * If pmd_none is true, older tlb entry will be normal page.
+	 * here to invalidate older tlb entry indexed by address
+	 * parameter address must be page fault address rather than
+	 * start address of pmd huge page
+	 */
+	local_flush_tlb_page(vma, address);
 	__update_tlb(vma, address, pte);
 }
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 78c84be..0f9187b 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -780,6 +780,7 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 		pgtable_t pgtable)
 {
 	struct mm_struct *mm = vma->vm_mm;
+	unsigned long start = addr & PMD_MASK;
 	pmd_t entry;
 	spinlock_t *ptl;
 
@@ -792,7 +793,7 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 			}
 			entry = pmd_mkyoung(*pmd);
 			entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
-			if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
+			if (pmdp_set_access_flags(vma, start, pmd, entry, 1))
 				update_mmu_cache_pmd(vma, addr, pmd);
 		}
 
@@ -813,7 +814,7 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 		pgtable = NULL;
 	}
 
-	set_pmd_at(mm, addr, pmd, entry);
+	set_pmd_at(mm, start, pmd, entry);
 	update_mmu_cache_pmd(vma, addr, pmd);
 
 out_unlock:
@@ -864,7 +865,7 @@ vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
 
 	track_pfn_insert(vma, &pgprot, pfn);
 
-	insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
+	insert_pfn_pmd(vma, vmf->address, vmf->pmd, pfn, pgprot, write, pgtable);
 	return VM_FAULT_NOPAGE;
 }
 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot);
diff --git a/mm/memory.c b/mm/memory.c
index dc7f354..c703458 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3592,7 +3592,7 @@ static vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
 
 	set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
 
-	update_mmu_cache_pmd(vma, haddr, vmf->pmd);
+	update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
 
 	/* fault is handled */
 	ret = 0;
-- 
1.8.3.1