+ powerpc-mm-use-set_pte_at_unchecked-for-internal-usages.patch added to mm-unstable branch

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

The patch titled
     Subject: powerpc: mm: use set_pte_at_unchecked() for internal usages
has been added to the -mm mm-unstable branch.  Its filename is
     powerpc-mm-use-set_pte_at_unchecked-for-internal-usages.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/powerpc-mm-use-set_pte_at_unchecked-for-internal-usages.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: Rohan McLure <rmclure@linux.ibm.com>
Subject: powerpc: mm: use set_pte_at_unchecked() for internal usages
Date: Wed, 12 Feb 2025 03:14:03 +1100

In the new set_ptes() API, set_pte_at() (a special case of set_ptes()) is
intended to be instrumented by the page table check facility.  There are
however several other routines that constitute the API for setting page
table entries, including set_pmd_at() among others.  Such routines are
themselves implemented in terms of set_ptes_at().

A future patch providing support for page table checking on powerpc must
take care to avoid duplicate calls to page_table_check_p{te,md,ud}_set(). 
Allow for assignment of pte entries without instrumentation through the
set_pte_at_unchecked() routine introduced in this patch.

Cause API-facing routines that call set_pte_at() to instead call
set_pte_at_unchecked(), which will remain uninstrumented by page table
check.  set_ptes() is itself implemented by calls to __set_pte_at(), so
this eliminates redundant code.

[ajd@linux.ibm.com: don't change to unchecked for early boot/kernel mappings]
Link: https://lkml.kernel.org/r/20250211161404.850215-11-ajd@linux.ibm.com
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/powerpc/include/asm/pgtable.h       |    2 ++
 arch/powerpc/mm/book3s64/pgtable.c       |    6 +++---
 arch/powerpc/mm/book3s64/radix_pgtable.c |    6 +++---
 arch/powerpc/mm/pgtable.c                |    8 ++++++++
 4 files changed, 16 insertions(+), 6 deletions(-)

--- a/arch/powerpc/include/asm/pgtable.h~powerpc-mm-use-set_pte_at_unchecked-for-internal-usages
+++ a/arch/powerpc/include/asm/pgtable.h
@@ -46,6 +46,8 @@ struct mm_struct;
 void set_ptes(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
 		pte_t pte, unsigned int nr);
 #define set_ptes set_ptes
+void set_pte_at_unchecked(struct mm_struct *mm, unsigned long addr,
+			  pte_t *ptep, pte_t pte);
 #define update_mmu_cache(vma, addr, ptep) \
 	update_mmu_cache_range(NULL, vma, addr, ptep, 1)
 
--- a/arch/powerpc/mm/book3s64/pgtable.c~powerpc-mm-use-set_pte_at_unchecked-for-internal-usages
+++ a/arch/powerpc/mm/book3s64/pgtable.c
@@ -129,7 +129,7 @@ void set_pmd_at(struct mm_struct *mm, un
 	WARN_ON(!(pmd_leaf(pmd)));
 #endif
 	trace_hugepage_set_pmd(addr, pmd_val(pmd));
-	return set_pte_at(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));
+	return set_pte_at_unchecked(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));
 }
 
 void set_pud_at(struct mm_struct *mm, unsigned long addr,
@@ -146,7 +146,7 @@ void set_pud_at(struct mm_struct *mm, un
 	WARN_ON(!(pud_leaf(pud)));
 #endif
 	trace_hugepage_set_pud(addr, pud_val(pud));
-	return set_pte_at(mm, addr, pudp_ptep(pudp), pud_pte(pud));
+	return set_pte_at_unchecked(mm, addr, pudp_ptep(pudp), pud_pte(pud));
 }
 
 static void do_serialize(void *arg)
@@ -557,7 +557,7 @@ void ptep_modify_prot_commit(struct vm_a
 	if (radix_enabled())
 		return radix__ptep_modify_prot_commit(vma, addr,
 						      ptep, old_pte, pte);
-	set_pte_at(vma->vm_mm, addr, ptep, pte);
+	set_pte_at_unchecked(vma->vm_mm, addr, ptep, pte);
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c~powerpc-mm-use-set_pte_at_unchecked-for-internal-usages
+++ a/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -1586,7 +1586,7 @@ void radix__ptep_modify_prot_commit(stru
 	    (atomic_read(&mm->context.copros) > 0))
 		radix__flush_tlb_page(vma, addr);
 
-	set_pte_at(mm, addr, ptep, pte);
+	set_pte_at_unchecked(mm, addr, ptep, pte);
 }
 
 int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
@@ -1597,7 +1597,7 @@ int pud_set_huge(pud_t *pud, phys_addr_t
 	if (!radix_enabled())
 		return 0;
 
-	set_pte_at(&init_mm, 0 /* radix unused */, ptep, new_pud);
+	set_pte_at_unchecked(&init_mm, 0 /* radix unused */, ptep, new_pud);
 
 	return 1;
 }
@@ -1644,7 +1644,7 @@ int pmd_set_huge(pmd_t *pmd, phys_addr_t
 	if (!radix_enabled())
 		return 0;
 
-	set_pte_at(&init_mm, 0 /* radix unused */, ptep, new_pmd);
+	set_pte_at_unchecked(&init_mm, 0 /* radix unused */, ptep, new_pmd);
 
 	return 1;
 }
--- a/arch/powerpc/mm/pgtable.c~powerpc-mm-use-set_pte_at_unchecked-for-internal-usages
+++ a/arch/powerpc/mm/pgtable.c
@@ -224,6 +224,14 @@ void set_ptes(struct mm_struct *mm, unsi
 	}
 }
 
+void set_pte_at_unchecked(struct mm_struct *mm, unsigned long addr,
+			  pte_t *ptep, pte_t pte)
+{
+	VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep));
+	pte = set_pte_filter(pte, addr);
+	__set_pte_at(mm, addr, ptep, pte, 0);
+}
+
 void unmap_kernel_page(unsigned long va)
 {
 	pmd_t *pmdp = pmd_off_k(va);
_

Patches currently in -mm which might be from rmclure@linux.ibm.com are

mm-page_table_check-reinstate-address-parameter-in-page_table_check_pud_set.patch
mm-page_table_check-reinstate-address-parameter-in-page_table_check_pmd_set.patch
mm-page_table_check-provide-addr-parameter-to-page_table_check_pte_set.patch
mm-page_table_check-reinstate-address-parameter-in-page_table_check_pud_clear.patch
mm-page_table_check-reinstate-address-parameter-in-page_table_check_pmd_clear.patch
mm-page_table_check-reinstate-address-parameter-in-page_table_check_pte_clear.patch
mm-provide-address-parameter-to-ptemdud_user_accessible_page.patch
powerpc-mm-add-pud_pfn-stub.patch
powerpc-mm-implement-_user_accessible_page-for-ptes.patch
powerpc-mm-use-set_pte_at_unchecked-for-internal-usages.patch
powerpc-mm-support-page-table-check.patch