[PATCH v11 11/11] powerpc: mm: Support page table check

Rohan McLure
2024-03-28T04:59:23Z

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
v10: Cause p{u,m}dp_huge_get_and_clear() to resemble one another
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/book3s/32/pgtable.h | 7 ++-
arch/powerpc/include/asm/book3s/64/pgtable.h | 45 +++++++++++++++-----
arch/powerpc/mm/book3s64/hash_pgtable.c | 4 ++
arch/powerpc/mm/book3s64/pgtable.c | 11 +++--
arch/powerpc/mm/book3s64/radix_pgtable.c | 3 ++
arch/powerpc/mm/pgtable.c | 4 ++
7 files changed, 61 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index a68b9e637eda..66a72f9078f5 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 83f7b98ef49f..703deb5749e6 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
@@ -314,7 +315,11 @@ 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 d8640ddbcad1..6199d2b4bded 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -145,6 +145,8 @@
#define PAGE_KERNEL_ROX __pgprot(_PAGE_BASE | _PAGE_KERNEL_ROX)

#ifndef __ASSEMBLY__
+#include <linux/page_table_check.h>
+
/*
* page table defines
*/
@@ -415,8 +417,11 @@ 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
@@ -425,11 +430,16 @@ 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);
}
@@ -1306,19 +1316,34 @@ 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/mm/book3s64/hash_pgtable.c b/arch/powerpc/mm/book3s64/hash_pgtable.c
index 871472f99a01..f200d55c35d8 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, 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 f7be5fa058e8..171e20e69441 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_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));
}

@@ -133,6 +135,7 @@ 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));
}

@@ -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, address, 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 e8da30536bd5..5e777a462a96 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>
@@ -1390,6 +1391,8 @@ 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 1e3bd1861b71..1a5c18bd8508 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 (;;) {

/*