[PATCH v11 10/11] powerpc: mm: Use set_pte_at_unchecked() for early-boot / internal usages

Rohan McLure
2024-03-28T04:58:25Z

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.

Also prefer set_pte_at_unchecked() in early-boot usages which should not be
instrumented.

Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
---
v9: New patch
v10: don't reuse __set_pte_at(), as that will not apply filters. Instead
use new set_pte_at_unchecked().
v11: Include the assertion that hwvalid => !protnone. It is possible that
some of these calls can be safely replaced with __set_pte_at(), however
that will have to be done at a later stage.
---
arch/powerpc/include/asm/pgtable.h | 2 ++
arch/powerpc/mm/book3s64/hash_pgtable.c | 2 +-
arch/powerpc/mm/book3s64/pgtable.c | 6 +++---
arch/powerpc/mm/book3s64/radix_pgtable.c | 8 ++++----
arch/powerpc/mm/nohash/book3e_pgtable.c | 2 +-
arch/powerpc/mm/pgtable.c | 8 ++++++++
arch/powerpc/mm/pgtable_32.c | 2 +-
7 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index f1ceae778cb1..ad0c1451502d 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/hash_pgtable.c b/arch/powerpc/mm/book3s64/hash_pgtable.c
index 988948d69bc1..871472f99a01 100644
--- a/arch/powerpc/mm/book3s64/hash_pgtable.c
+++ b/arch/powerpc/mm/book3s64/hash_pgtable.c
@@ -165,7 +165,7 @@ int hash__map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t prot)
ptep = pte_alloc_kernel(pmdp, ea);
if (!ptep)
return -ENOMEM;
- set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT, prot));
+ set_pte_at_unchecked(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT, prot));
} else {
/*
* If the mm subsystem is not fully up, we cannot create a
diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 83823db3488b..f7be5fa058e8 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -116,7 +116,7 @@ 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,
@@ -133,7 +133,7 @@ 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)
@@ -539,7 +539,7 @@ 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 15e88f1439ec..e8da30536bd5 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -109,7 +109,7 @@ static int early_map_kernel_page(unsigned long ea, unsigned long pa,
ptep = pte_offset_kernel(pmdp, ea);

set_the_pte:
- set_pte_at(&init_mm, ea, ptep, pfn_pte(pfn, flags));
+ set_pte_at_unchecked(&init_mm, ea, ptep, pfn_pte(pfn, flags));
asm volatile("ptesync": : :"memory");
return 0;
}
@@ -1522,7 +1522,7 @@ 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)
@@ -1533,7 +1533,7 @@ 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;
}
@@ -1580,7 +1580,7 @@ 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/nohash/book3e_pgtable.c b/arch/powerpc/mm/nohash/book3e_pgtable.c
index 1c5e4ecbebeb..10d487b2b991 100644
--- a/arch/powerpc/mm/nohash/book3e_pgtable.c
+++ b/arch/powerpc/mm/nohash/book3e_pgtable.c
@@ -111,7 +111,7 @@ int __ref map_kernel_page(unsigned long ea, phys_addr_t pa, pgprot_t prot)
}
ptep = pte_offset_kernel(pmdp, ea);
}
- set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT, prot));
+ set_pte_at_unchecked(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT, prot));

smp_wmb();
return 0;
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 9e7ba9c3851f..1e3bd1861b71 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);
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index face94977cb2..fb14c0a6f761 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -89,7 +89,7 @@ int __ref map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
* hash table
*/
BUG_ON((pte_present(*pg) | pte_hashpte(*pg)) && pgprot_val(prot));
- set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT, prot));
+ set_pte_at_unchecked(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT, prot));
}
smp_wmb();
return err;