[PATCH v18 11/12] powerpc/mm: Use set_pte_at_unchecked() for internal usages

Andrew Donnellan
2025-12-18T17:11:47Z

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>
Acked-by: Madhavan Srinivasan <maddy@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 859cdbaa54a7fa159d5bbd4653f7871381f4910f..dcd3a88caaf634fef26fa57f5b8852274e0d4cb5 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -34,6 +34,8 @@ 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 e3485db7de027cc6a20ffb5a80dbdc53261ebb3e..97db2f42ea3d3bd476d0ef03da47ff325eb73db9 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -127,7 +127,7 @@ 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,
@@ -144,7 +144,7 @@ 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)
@@ -550,7 +550,7 @@ 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 73977dbabcf2615252f82a09b97f719b7fe68164..b2541bf33d01cbb59562866d844354b39b14a86c 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -1606,7 +1606,7 @@ 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)
@@ -1617,7 +1617,7 @@ 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;
}
@@ -1664,7 +1664,7 @@ 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 56d7e8960e77d877390d6bcbf0d8a305cc222101..7b69cd16e011c31fffac2439a76ba20e00fc9a78 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);

--
2.52.0