[PATCH v18 12/12] powerpc/mm: Support page table check

Andrew Donnellan
2025-12-18T17:11:56Z

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

On creation and clearing of a page table mapping, instrument such calls
by invoking page_table_check_pte_set and page_table_check_pte_clear
respectively. These calls serve as a sanity check against illegal
mappings.

Enable ARCH_SUPPORTS_PAGE_TABLE_CHECK on powerpc, except when HUGETLB_PAGE
is enabled (powerpc has some weirdness in how it implements
set_huge_pte_at(), which may require some further work).

See also:

riscv support in commit 3fee229a8eb9 ("riscv/mm: enable
ARCH_SUPPORTS_PAGE_TABLE_CHECK")
arm64 in commit 42b2547137f5 ("arm64/mm: enable
ARCH_SUPPORTS_PAGE_TABLE_CHECK")
x86_64 in commit d283d422c6c4 ("x86: mm: add x86_64 support for page table
check")

[ajd@linux.ibm.com: rebase, add additional instrumentation, misc fixes]
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Acked-by: Madhavan Srinivasan <maddy@linux.ibm.com>
---
v18:
- instrument the new pudp_invalidate()
- don't allow with HUGETLB_PAGE, for now
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/book3s/32/pgtable.h | 7 ++++-
arch/powerpc/include/asm/book3s/64/pgtable.h | 45 +++++++++++++++++++++-------
arch/powerpc/include/asm/nohash/pgtable.h | 8 ++++-
arch/powerpc/mm/book3s64/hash_pgtable.c | 4 +++
arch/powerpc/mm/book3s64/pgtable.c | 19 ++++++++----
arch/powerpc/mm/book3s64/radix_pgtable.c | 3 ++
arch/powerpc/mm/pgtable.c | 4 +++
8 files changed, 73 insertions(+), 18 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 9537a61ebae02dbfe44918232eb6114c2b763387..271690445a454b642041e47b0d73cc3fe7d38ae5 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -172,6 +172,7 @@ config PPC
select ARCH_STACKWALK
select ARCH_SUPPORTS_ATOMIC_RMW
select ARCH_SUPPORTS_DEBUG_PAGEALLOC if PPC_BOOK3S || PPC_8xx
+ select ARCH_SUPPORTS_PAGE_TABLE_CHECK if !HUGETLB_PAGE
select ARCH_SUPPORTS_SCHED_MC if SMP
select ARCH_SUPPORTS_SCHED_SMT if PPC64 && SMP
select SCHED_MC if ARCH_SUPPORTS_SCHED_MC
diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index 2edca1068b6f31e64ddc4f39f594bb3ac27a8435..dcbae85218304f9062e4414db17f589246733819 100644
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -202,6 +202,7 @@ void unmap_kernel_page(unsigned long va);
#ifndef __ASSEMBLER__
#include <linux/sched.h>
#include <linux/threads.h>
+#include <linux/page_table_check.h>

/* Bits to mask out from a PGD to get to the PUD page */
#define PGD_MASKED_BITS 0
@@ -315,7 +316,11 @@ static inline int __ptep_test_and_clear_young(struct mm_struct *mm,
static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
pte_t *ptep)
{
- return __pte(pte_update(mm, addr, ptep, ~_PAGE_HASHPTE, 0, 0));
+ pte_t old_pte = __pte(pte_update(mm, addr, ptep, ~_PAGE_HASHPTE, 0, 0));
+
+ page_table_check_pte_clear(mm, addr, old_pte);
+
+ return old_pte;
}

#define __HAVE_ARCH_PTEP_SET_WRPROTECT
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 2d69a827594f3c8593283fa11acd4750577e71a7..1a91762b455d9380481eef01f7f86ba5f856e375 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -144,6 +144,8 @@
#define PAGE_KERNEL_ROX __pgprot(_PAGE_BASE | _PAGE_KERNEL_ROX)

#ifndef __ASSEMBLER__
+#include <linux/page_table_check.h>
+
/*
* page table defines
*/
@@ -416,8 +418,11 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
- unsigned long old = pte_update(mm, addr, ptep, ~0UL, 0, 0);
- return __pte(old);
+ pte_t old_pte = __pte(pte_update(mm, addr, ptep, ~0UL, 0, 0));
+
+ page_table_check_pte_clear(mm, addr, old_pte);
+
+ return old_pte;
}

#define __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL
@@ -426,11 +431,16 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
pte_t *ptep, int full)
{
if (full && radix_enabled()) {
+ pte_t old_pte;
+
/*
* We know that this is a full mm pte clear and
* hence can be sure there is no parallel set_pte.
*/
- return radix__ptep_get_and_clear_full(mm, addr, ptep, full);
+ old_pte = radix__ptep_get_and_clear_full(mm, addr, ptep, full);
+ page_table_check_pte_clear(mm, addr, old_pte);
+
+ return old_pte;
}
return ptep_get_and_clear(mm, addr, ptep);
}
@@ -1301,19 +1311,34 @@ extern int pudp_test_and_clear_young(struct vm_area_struct *vma,
static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
unsigned long addr, pmd_t *pmdp)
{
- if (radix_enabled())
- return radix__pmdp_huge_get_and_clear(mm, addr, pmdp);
- return hash__pmdp_huge_get_and_clear(mm, addr, pmdp);
+ pmd_t old_pmd;
+
+ if (radix_enabled()) {
+ old_pmd = radix__pmdp_huge_get_and_clear(mm, addr, pmdp);
+ } else {
+ old_pmd = hash__pmdp_huge_get_and_clear(mm, addr, pmdp);
+ }
+
+ page_table_check_pmd_clear(mm, addr, old_pmd);
+
+ return old_pmd;
}

#define __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR
static inline pud_t pudp_huge_get_and_clear(struct mm_struct *mm,
unsigned long addr, pud_t *pudp)
{
- if (radix_enabled())
- return radix__pudp_huge_get_and_clear(mm, addr, pudp);
- BUG();
- return *pudp;
+ pud_t old_pud;
+
+ if (radix_enabled()) {
+ old_pud = radix__pudp_huge_get_and_clear(mm, addr, pudp);
+ } else {
+ BUG();
+ }
+
+ page_table_check_pud_clear(mm, addr, old_pud);
+
+ return old_pud;
}

static inline pmd_t pmdp_collapse_flush(struct vm_area_struct *vma,
diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h
index 9bf3e40f27b645da660cbeeb561f08eeef180b1b..e6da5eaccff632a353139f27bf54472e716ac246 100644
--- a/arch/powerpc/include/asm/nohash/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/pgtable.h
@@ -29,6 +29,8 @@ static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, p

#ifndef __ASSEMBLER__

+#include <linux/page_table_check.h>
+
extern int icache_44x_need_flush;

#ifndef pte_huge_size
@@ -122,7 +124,11 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
pte_t *ptep)
{
- return __pte(pte_update(mm, addr, ptep, ~0UL, 0, 0));
+ pte_t old_pte = __pte(pte_update(mm, addr, ptep, ~0UL, 0, 0));
+
+ page_table_check_pte_clear(mm, addr, old_pte);
+
+ return old_pte;
}
#define __HAVE_ARCH_PTEP_GET_AND_CLEAR

diff --git a/arch/powerpc/mm/book3s64/hash_pgtable.c b/arch/powerpc/mm/book3s64/hash_pgtable.c
index 82d31177630b810a70c9e7797f1f163fa97ccfaf..ac2a24d15d2e3733bd013eb168b2656ad61e7af7 100644
--- a/arch/powerpc/mm/book3s64/hash_pgtable.c
+++ b/arch/powerpc/mm/book3s64/hash_pgtable.c
@@ -8,6 +8,7 @@
#include <linux/sched.h>
#include <linux/mm_types.h>
#include <linux/mm.h>
+#include <linux/page_table_check.h>
#include <linux/stop_machine.h>

#include <asm/sections.h>
@@ -230,6 +231,9 @@ pmd_t hash__pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long addres

pmd = *pmdp;
pmd_clear(pmdp);
+
+ page_table_check_pmd_clear(vma->vm_mm, address, pmd);
+
/*
* Wait for all pending hash_page to finish. This is needed
* in case of subpage collapse. When we collapse normal pages
diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 97db2f42ea3d3bd476d0ef03da47ff325eb73db9..4b09c04654a8f26e84f811df61461d83ae71f299 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -10,6 +10,7 @@
#include <linux/pkeys.h>
#include <linux/debugfs.h>
#include <linux/proc_fs.h>
+#include <linux/page_table_check.h>

#include <asm/pgalloc.h>
#include <asm/tlb.h>
@@ -127,6 +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));
+ page_table_check_pmd_set(mm, addr, pmdp, pmd);
return set_pte_at_unchecked(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));
}

@@ -144,6 +146,7 @@ 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));
+ page_table_check_pud_set(mm, addr, pudp, pud);
return set_pte_at_unchecked(mm, addr, pudp_ptep(pudp), pud_pte(pud));
}

@@ -179,23 +182,27 @@ void serialize_against_pte_lookup(struct mm_struct *mm)
pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp)
{
- unsigned long old_pmd;
+ pmd_t old_pmd;

VM_WARN_ON_ONCE(!pmd_present(*pmdp));
- old_pmd = pmd_hugepage_update(vma->vm_mm, address, pmdp, _PAGE_PRESENT, _PAGE_INVALID);
+ old_pmd = __pmd(pmd_hugepage_update(vma->vm_mm, address, pmdp, _PAGE_PRESENT, _PAGE_INVALID));
flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
- return __pmd(old_pmd);
+ page_table_check_pmd_clear(vma->vm_mm, address, old_pmd);
+
+ return old_pmd;
}

pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address,
pud_t *pudp)
{
- unsigned long old_pud;
+ pud_t old_pud;

VM_WARN_ON_ONCE(!pud_present(*pudp));
- old_pud = pud_hugepage_update(vma->vm_mm, address, pudp, _PAGE_PRESENT, _PAGE_INVALID);
+ old_pud = __pud(pud_hugepage_update(vma->vm_mm, address, pudp, _PAGE_PRESENT, _PAGE_INVALID));
flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
- return __pud(old_pud);
+ page_table_check_pud_clear(vma->vm_mm, address, old_pud);
+
+ return old_pud;
}

pmd_t pmdp_huge_get_and_clear_full(struct vm_area_struct *vma,
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index b2541bf33d01cbb59562866d844354b39b14a86c..10aced261cff4d39e64407e31ac05e9eb340007b 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -14,6 +14,7 @@
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/mm.h>
+#include <linux/page_table_check.h>
#include <linux/hugetlb.h>
#include <linux/string_helpers.h>
#include <linux/memory.h>
@@ -1474,6 +1475,8 @@ pmd_t radix__pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long addre
pmd = *pmdp;
pmd_clear(pmdp);

+ page_table_check_pmd_clear(vma->vm_mm, address, pmd);
+
radix__flush_tlb_collapsed_pmd(vma->vm_mm, address);

return pmd;
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 7b69cd16e011c31fffac2439a76ba20e00fc9a78..a9be337be3e461fdffa7181a87376cd8329aa9e0 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -22,6 +22,7 @@
#include <linux/mm.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
+#include <linux/page_table_check.h>
#include <linux/hugetlb.h>
#include <asm/tlbflush.h>
#include <asm/tlb.h>
@@ -206,6 +207,9 @@ void set_ptes(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
* and not hw_valid ptes. Hence there is no translation cache flush
* involved that need to be batched.
*/
+
+ page_table_check_ptes_set(mm, addr, ptep, pte, nr);
+
for (;;) {

/*

--
2.52.0