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Date:   Tue, 9 May 2023 21:51:16 -0700 (PDT)
From:   Hugh Dickins <hughd@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
cc:     Mike Kravetz <mike.kravetz@...cle.com>,
        Mike Rapoport <rppt@...nel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Matthew Wilcox <willy@...radead.org>,
        David Hildenbrand <david@...hat.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Qi Zheng <zhengqi.arch@...edance.com>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Greg Ungerer <gerg@...ux-m68k.org>,
        Michal Simek <monstr@...str.eu>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Helge Deller <deller@....de>,
        John David Anglin <dave.anglin@...l.net>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Alexandre Ghiti <alexghiti@...osinc.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        "David S. Miller" <davem@...emloft.net>,
        Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>, x86@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-ia64@...r.kernel.org,
        linux-m68k@...ts.linux-m68k.org, linux-mips@...r.kernel.org,
        linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH 07/23] mips: update_mmu_cache() can replace __update_tlb()

Don't make update_mmu_cache() a wrapper around __update_tlb(): call it
directly, and use the ptep (or pmdp) provided by the caller, instead of
re-calling pte_offset_map() - which would raise a question of whether a
pte_unmap() is needed to balance it.

Check whether the "ptep" provided by the caller is actually the pmdp,
instead of testing pmd_huge(): or test pmd_huge() too and warn if it
disagrees?  This is "hazardous" territory: needs review and testing.

Signed-off-by: Hugh Dickins <hughd@...gle.com>
---
 arch/mips/include/asm/pgtable.h | 15 +++------------
 arch/mips/mm/tlb-r3k.c          |  5 +++--
 arch/mips/mm/tlb-r4k.c          |  9 +++------
 3 files changed, 9 insertions(+), 20 deletions(-)

diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 574fa14ac8b2..9175dfab08d5 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -565,15 +565,8 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
 }
 #endif
 
-extern void __update_tlb(struct vm_area_struct *vma, unsigned long address,
-	pte_t pte);
-
-static inline void update_mmu_cache(struct vm_area_struct *vma,
-	unsigned long address, pte_t *ptep)
-{
-	pte_t pte = *ptep;
-	__update_tlb(vma, address, pte);
-}
+extern void update_mmu_cache(struct vm_area_struct *vma,
+	unsigned long address, pte_t *ptep);
 
 #define	__HAVE_ARCH_UPDATE_MMU_TLB
 #define update_mmu_tlb	update_mmu_cache
@@ -581,9 +574,7 @@ static inline void update_mmu_cache(struct vm_area_struct *vma,
 static inline void update_mmu_cache_pmd(struct vm_area_struct *vma,
 	unsigned long address, pmd_t *pmdp)
 {
-	pte_t pte = *(pte_t *)pmdp;
-
-	__update_tlb(vma, address, pte);
+	update_mmu_cache(vma, address, (pte_t *)pmdp);
 }
 
 /*
diff --git a/arch/mips/mm/tlb-r3k.c b/arch/mips/mm/tlb-r3k.c
index 53dfa2b9316b..e5722cd8dd6d 100644
--- a/arch/mips/mm/tlb-r3k.c
+++ b/arch/mips/mm/tlb-r3k.c
@@ -176,7 +176,8 @@ void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
 	}
 }
 
-void __update_tlb(struct vm_area_struct *vma, unsigned long address, pte_t pte)
+void update_mmu_cache(struct vm_area_struct *vma,
+		      unsigned long address, pte_t *ptep)
 {
 	unsigned long asid_mask = cpu_asid_mask(&current_cpu_data);
 	unsigned long flags;
@@ -203,7 +204,7 @@ void __update_tlb(struct vm_area_struct *vma, unsigned long address, pte_t pte)
 	BARRIER;
 	tlb_probe();
 	idx = read_c0_index();
-	write_c0_entrylo0(pte_val(pte));
+	write_c0_entrylo0(pte_val(*ptep));
 	write_c0_entryhi(address | pid);
 	if (idx < 0) {					/* BARRIER */
 		tlb_write_random();
diff --git a/arch/mips/mm/tlb-r4k.c b/arch/mips/mm/tlb-r4k.c
index 1b939abbe4ca..c96725d17cab 100644
--- a/arch/mips/mm/tlb-r4k.c
+++ b/arch/mips/mm/tlb-r4k.c
@@ -290,14 +290,14 @@ void local_flush_tlb_one(unsigned long page)
  * updates the TLB with the new pte(s), and another which also checks
  * for the R4k "end of page" hardware bug and does the needy.
  */
-void __update_tlb(struct vm_area_struct * vma, unsigned long address, pte_t pte)
+void update_mmu_cache(struct vm_area_struct *vma,
+		      unsigned long address, pte_t *ptep)
 {
 	unsigned long flags;
 	pgd_t *pgdp;
 	p4d_t *p4dp;
 	pud_t *pudp;
 	pmd_t *pmdp;
-	pte_t *ptep;
 	int idx, pid;
 
 	/*
@@ -326,10 +326,9 @@ void __update_tlb(struct vm_area_struct * vma, unsigned long address, pte_t pte)
 	idx = read_c0_index();
 #ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
 	/* this could be a huge page  */
-	if (pmd_huge(*pmdp)) {
+	if (ptep == (pte_t *)pmdp) {
 		unsigned long lo;
 		write_c0_pagemask(PM_HUGE_MASK);
-		ptep = (pte_t *)pmdp;
 		lo = pte_to_entrylo(pte_val(*ptep));
 		write_c0_entrylo0(lo);
 		write_c0_entrylo1(lo + (HPAGE_SIZE >> 7));
@@ -344,8 +343,6 @@ void __update_tlb(struct vm_area_struct * vma, unsigned long address, pte_t pte)
 	} else
 #endif
 	{
-		ptep = pte_offset_map(pmdp, address);
-
 #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
 #ifdef CONFIG_XPA
 		write_c0_entrylo0(pte_to_entrylo(ptep->pte_high));
-- 
2.35.3

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