powerpc/mm: support page table check

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]
Link: https://lkml.kernel.org/r/20251219-pgtable_check_v18rebase-v18-12-755bc151a50b@linux.ibm.com
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: "Christophe Leroy (CS GROUP)" <chleroy@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Donet Tom <donettom@linux.ibm.com>
Cc: Guo Weikang <guoweikang.kernel@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Miehlbradt <nicholas@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Cc: Thomas Huth <thuth@redhat.com>
Cc: "Vishal Moola (Oracle)" <vishal.moola@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

3 files changed, 48 insertions, 12 deletions

diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index 2edca1068b6f..dcbae8521830 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 2d69a827594f..1a91762b455d 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 9bf3e40f27b6..e6da5eaccff6 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