[PATCH v15 12/13] powerpc: mm: Use set_pte_at_unchecked() for internal usages

[Andrew Donnellan <ajd@linux.ibm.com>]

From: Rohan McLure <rmclure@linux.ibm.com>

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]
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
---
v13: don't use the unchecked version for early-boot kernel mappings (Pasha)
---
 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(-)

diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index d0938e9c33fb..4fe970992147 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/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)
 
diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 0db01e10a3f8..1468a815fa5e 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -128,7 +128,7 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
 	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,
@@ -145,7 +145,7 @@ void set_pud_at(struct mm_struct *mm, unsigned long addr,
 	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)
@@ -551,7 +551,7 @@ void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr,
 	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
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index 9f764bc42b8c..2a52089018a5 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -1600,7 +1600,7 @@ void radix__ptep_modify_prot_commit(struct vm_area_struct *vma,
 	    (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)
@@ -1611,7 +1611,7 @@ int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
 	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;
 }
@@ -1658,7 +1658,7 @@ int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
 	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;
 }
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 61df5aed7989..4cc9af7961ca 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -224,6 +224,14 @@ void set_ptes(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
 	}
 }
 
+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);
-- 
2.49.0