Now that all kernel page table manipulations are routed through the fixmap API if r/o page tables are enabled, we can remove write access from the linear mapping of those pages.
Signed-off-by: Ard Biesheuvel <[email protected]> --- arch/arm64/include/asm/pgalloc.h | 6 +++++ arch/arm64/mm/mmu.c | 24 +++++++++++++++++++- 2 files changed, 29 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h index 18a5bb0c9ee4..073482634e74 100644 --- a/arch/arm64/include/asm/pgalloc.h +++ b/arch/arm64/include/asm/pgalloc.h @@ -20,6 +20,9 @@ #define __HAVE_ARCH_PMD_FREE #define __HAVE_ARCH_PTE_ALLOC_ONE #define __HAVE_ARCH_PTE_FREE +#define __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL +#define __HAVE_ARCH_PTE_FREE_KERNEL + #include <asm-generic/pgalloc.h> #define PGD_SIZE (PTRS_PER_PGD * sizeof(pgd_t)) @@ -27,6 +30,9 @@ pgtable_t pte_alloc_one(struct mm_struct *mm); void pte_free(struct mm_struct *mm, struct page *pte_page); +pte_t *pte_alloc_one_kernel(struct mm_struct *mm); +void pte_free_kernel(struct mm_struct *mm, pte_t *pte); + #if CONFIG_PGTABLE_LEVELS > 2 pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr); diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 949846654797..971501535757 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1402,7 +1402,7 @@ int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr) table = pte_offset_kernel(pmdp, addr); pmd_clear(pmdp); __flush_tlb_kernel_pgtable(addr); - pte_free_kernel(NULL, table); + pte_free_kernel(&init_mm, table); return 1; } @@ -1709,3 +1709,25 @@ void pte_free(struct mm_struct *mm, struct page *pte_page) pgtable_pte_page_dtor(pte_page); __free_page(pte_page); } + +pte_t *pte_alloc_one_kernel(struct mm_struct *mm) +{ + pte_t *pte = __pte_alloc_one_kernel(mm); + + VM_BUG_ON(mm != &init_mm); + + if (!pte) + return NULL; + if (page_tables_are_ro()) + set_pgtable_ro(pte); + return pte; +} + +void pte_free_kernel(struct mm_struct *mm, pte_t *pte) +{ + VM_BUG_ON(mm != &init_mm); + + if (page_tables_are_ro()) + set_pgtable_rw(pte); + free_page((u64)pte); +} -- 2.30.2 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
