Instead of directly dereferencing page tables entries, which can cause
issues (see commit 20a004e7b017 ("arm64: mm: Use READ_ONCE/WRITE_ONCE when
accessing page tables"), let's introduce new functions to get the
pud/p4d/pgd entries (the pte and pmd versions already exist).
Note that arm pgd_t is actually an array so pgdp_get() is defined as a
macro to avoid a build error.
Those new functions will be used in subsequent commits by the riscv
architecture.
Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
---
arch/arm/include/asm/pgtable.h | 2 ++
include/linux/pgtable.h | 21 +++++++++++++++++++++
2 files changed, 23 insertions(+)
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 16b02f44c7d3..d657b84b6bf7 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -151,6 +151,8 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
+#define pgdp_get(pgpd) READ_ONCE(*pgdp)
+
#define pud_page(pud) pmd_page(__pmd(pud_val(pud)))
#define pud_write(pud) pmd_write(__pmd(pud_val(pud)))
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index af7639c3b0a3..8b7daccd11be 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -292,6 +292,27 @@ static inline pmd_t pmdp_get(pmd_t *pmdp)
}
#endif
+#ifndef pudp_get
+static inline pud_t pudp_get(pud_t *pudp)
+{
+ return READ_ONCE(*pudp);
+}
+#endif
+
+#ifndef p4dp_get
+static inline p4d_t p4dp_get(p4d_t *p4dp)
+{
+ return READ_ONCE(*p4dp);
+}
+#endif
+
+#ifndef pgdp_get
+static inline pgd_t pgdp_get(pgd_t *pgdp)
+{
+ return READ_ONCE(*pgdp);
+}
+#endif
+
#ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
unsigned long address,
--
2.39.2
