On 11/13/22 06:56, Anshuman Khandual wrote:
> +pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
> +{
> + if (IS_ENABLED(CONFIG_ARM64_WORKAROUND_2645198)) {
> + pte_t pte = READ_ONCE(*ptep);
> + /*
> + * Break-before-make (BBM) is required for all user space mappings
> + * when the permission changes from executable to non-executable
> + * in cases where cpu is affected with errata #2645198.
> + */
> + if (pte_user_exec(pte) && cpus_have_const_cap(ARM64_WORKAROUND_2645198))
> + return huge_ptep_clear_flush(vma, addr, ptep);
> + }
> + return huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
> +}
> +
> +void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep,
> + pte_t old_pte, pte_t pte)
> +{
> + set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
> +}
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 9a7c38965154..c1fb0ce1473c 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1702,3 +1702,24 @@ static int __init prevent_bootmem_remove_init(void)
> }
> early_initcall(prevent_bootmem_remove_init);
> #endif
> +
> +pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
> +{
> + if (IS_ENABLED(CONFIG_ARM64_WORKAROUND_2645198)) {
> + pte_t pte = READ_ONCE(*ptep);
> + /*
> + * Break-before-make (BBM) is required for all user space mappings
> + * when the permission changes from executable to non-executable
> + * in cases where cpu is affected with errata #2645198.
> + */
> + if (pte_user_exec(pte) && cpus_have_const_cap(ARM64_WORKAROUND_2645198))
> + return ptep_clear_flush(vma, addr, ptep);
> + }
> + return ptep_get_and_clear(vma->vm_mm, addr, ptep);
> +}
> +
> +void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep,
> + pte_t old_pte, pte_t pte)
> +{
> + __set_pte_at(vma->vm_mm, addr, ptep, pte);
> +}
Will change this __set_pte_at() to set_pte_at() instead like the generic version, which also
makes sure that page_table_check_pte_set() gets called on the way, also making it similar to
the HugeTLB implementation huge_ptep_modify_prot_commit().
