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 for all platforms.

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")

Reviewed-by: Christophe Leroy <redacted>
Signed-off-by: Rohan McLure <redacted>
---
v9: Updated for new API. Instrument pmdp_collapse_flush's two
constituent calls to avoid header hell
---
  arch/powerpc/Kconfig                         |  1 +
  arch/powerpc/include/asm/book3s/32/pgtable.h |  7 +++-
  arch/powerpc/include/asm/book3s/64/pgtable.h | 39 ++++++++++++++++----
  arch/powerpc/mm/book3s64/hash_pgtable.c      |  4 ++
  arch/powerpc/mm/book3s64/pgtable.c           | 13 +++++--
  arch/powerpc/mm/book3s64/radix_pgtable.c     |  3 ++
  arch/powerpc/mm/pgtable.c                    |  4 ++
  7 files changed, 58 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 6f105ee4f3cf..5bd6d367ef40 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -166,6 +166,7 @@ config PPC
  	select ARCH_STACKWALK
  	select ARCH_SUPPORTS_ATOMIC_RMW
  	select ARCH_SUPPORTS_DEBUG_PAGEALLOC	if PPC_BOOK3S || PPC_8xx || 40x
+	select ARCH_SUPPORTS_PAGE_TABLE_CHECK
  	select ARCH_USE_BUILTIN_BSWAP
  	select ARCH_USE_CMPXCHG_LOCKREF		if PPC64
  	select ARCH_USE_MEMTEST

diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index bd6f8cdd25aa..48f4e7b98340 100644
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h

@@ -201,6 +201,7 @@ void unmap_kernel_page(unsigned long va);
  #ifndef __ASSEMBLY__
  #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

@@ -319,7 +320,11 @@ 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, 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 dd3e7b190ab7..834c997ba657 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h

@@ -151,6 +151,8 @@
  #define PAGE_KERNEL_ROX	__pgprot(_PAGE_BASE | _PAGE_KERNEL_ROX)
  
  #ifndef __ASSEMBLY__
+#include <linux/page_table_check.h>
+
  /*
   * page table defines
   */

@@ -421,8 +423,11 @@ 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, old_pte);
+
+	return old_pte;
  }
  
  #define __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL

@@ -431,11 +436,16 @@ 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, old_pte);
+
+		return old_pte;
  	}
  	return ptep_get_and_clear(mm, addr, ptep);
  }

@@ -1339,17 +1349,30 @@ 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, 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);
+	pud_t old_pud;

  	BUG();
  	return *pudp;
  }

diff --git a/arch/powerpc/mm/book3s64/hash_pgtable.c b/arch/powerpc/mm/book3s64/hash_pgtable.c
index ae52c8db45b7..d6bde756e4a6 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>

@@ -231,6 +232,9 @@ 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, 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 9a0a2accb261..194df0e4a33d 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 <misc/cxl-base.h>
  
  #include <asm/pgalloc.h>

@@ -116,6 +117,7 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
  	WARN_ON(!(pmd_large(pmd)));
  #endif
  	trace_hugepage_set_pmd(addr, pmd_val(pmd));
+	page_table_check_pmd_set(mm, pmdp, pmd);
  	return __set_pte_at(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd), 0);
  }
  

@@ -133,7 +135,8 @@ void set_pud_at(struct mm_struct *mm, unsigned long addr,
  	WARN_ON(!(pud_large(pud)));
  #endif
  	trace_hugepage_set_pud(addr, pud_val(pud));
-	return set_pte_at(mm, addr, pudp_ptep(pudp), pud_pte(pud));
+	page_table_check_pud_set(mm, pudp, pud);
+	return __set_pte_at(mm, addr, pudp_ptep(pudp), pud_pte(pud), 0);

  }
  
  static void do_serialize(void *arg)

@@ -168,11 +171,13 @@ 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;
  
-	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, old_pmd);
+
+	return old_pmd;
  }
  
  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 ae4a5f66ccd2..9ed38466a99a 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>

@@ -1404,6 +1405,8 @@ 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, 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 e8e0289d7ab0..bccc96ba2471 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, ptep, pte, nr);
+
  	for (;;) {
  
  		/*