+ mips-update_mmu_cache-can-replace-__update_tlb.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mips: update_mmu_cache() can replace __update_tlb()
has been added to the -mm mm-unstable branch.  Its filename is
     mips-update_mmu_cache-can-replace-__update_tlb.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mips-update_mmu_cache-can-replace-__update_tlb.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Hugh Dickins <hughd@google.com>
Subject: mips: update_mmu_cache() can replace __update_tlb()
Date: Thu, 8 Jun 2023 12:17:24 -0700 (PDT)

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.

Link: https://lkml.kernel.org/r/178970b0-1539-8aac-76fd-972c6c46ec17@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: John David Anglin <dave.anglin@bell.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Palmer Dabbelt <palmer@rivosync.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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(-)

--- a/arch/mips/include/asm/pgtable.h~mips-update_mmu_cache-can-replace-__update_tlb
+++ a/arch/mips/include/asm/pgtable.h
@@ -565,15 +565,8 @@ static inline pte_t pte_swp_clear_exclus
 }
 #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(stru
 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);
 }
 
 /*
--- a/arch/mips/mm/tlb-r3k.c~mips-update_mmu_cache-can-replace-__update_tlb
+++ a/arch/mips/mm/tlb-r3k.c
@@ -176,7 +176,8 @@ finish:
 	}
 }
 
-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
 	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();
--- a/arch/mips/mm/tlb-r4k.c~mips-update_mmu_cache-can-replace-__update_tlb
+++ a/arch/mips/mm/tlb-r4k.c
@@ -290,14 +290,14 @@ void local_flush_tlb_one(unsigned long p
  * 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
 	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
 	} 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));
_

Patches currently in -mm which might be from hughd@google.com are

arm-allow-pte_offset_map-to-fail.patch
arm64-allow-pte_offset_map-to-fail.patch
arm64-hugetlb-pte_alloc_huge-pte_offset_huge.patch
ia64-hugetlb-pte_alloc_huge-pte_offset_huge.patch
m68k-allow-pte_offset_map-to-fail.patch
microblaze-allow-pte_offset_map-to-fail.patch
mips-update_mmu_cache-can-replace-__update_tlb.patch
parisc-add-pte_unmap-to-balance-get_ptep.patch
parisc-unmap_uncached_pte-use-pte_offset_kernel.patch
parisc-hugetlb-pte_alloc_huge-pte_offset_huge.patch
powerpc-kvmppc_unmap_free_pmd-pte_offset_kernel.patch
powerpc-allow-pte_offset_map-to-fail.patch
powerpc-hugetlb-pte_alloc_huge.patch
riscv-hugetlb-pte_alloc_huge-pte_offset_huge.patch
s390-allow-pte_offset_map_lock-to-fail.patch
s390-gmap-use-pte_unmap_unlock-not-spin_unlock.patch
sh-hugetlb-pte_alloc_huge-pte_offset_huge.patch
sparc-hugetlb-pte_alloc_huge-pte_offset_huge.patch
sparc-allow-pte_offset_map-to-fail.patch
sparc-iounit-and-iommu-use-pte_offset_kernel.patch
x86-allow-get_locked_pte-to-fail.patch
x86-sme_populate_pgd-use-pte_offset_kernel.patch
xtensa-add-pte_unmap-to-balance-pte_offset_map.patch