From: Alexandre Ghiti alexghiti@rivosinc.com

[ Upstream commit eba2591d99d1f14a04c8a8a845ab0795b93f5646 ]

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@rivosinc.com Link: https://lore.kernel.org/r/20231213203001.179237-3-alexghiti@rivosinc.com Signed-off-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: WangYuli wangyuli@uniontech.com --- 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,