[v9,7/7] 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 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 <christophe.leroy@csgroup.eu>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
---
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(-)

Le 30/11/2023 à 03:54, Rohan McLure a écrit :
> 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 <christophe.leroy@csgroup.eu>
> Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
> ---
> 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;

Should go inside the block below.

> +
> +	if (radix_enabled()) {
> +		old_pud = radix__pudp_huge_get_and_clear(mm, addr, pudp);
> +		page_table_check_pud_clear(mm, old_pud);
> +		return old_pud;
> +	}

Otherwise, could implemented as follows in order to be similar to 
pmdp_huge_get_and_clear()

{
	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, old_pud);

	return 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);

Did you miss that from previous patch ?

>   }
>   
>   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 (;;) {
>   
>   		/*