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SubjectRe: [PATCH v7 13/39] arm64/mm: Map pages for guarded control stack
Date

Hello,

Mark Brown <broonie@kernel.org> writes:

> diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
> index 645fe60d000f..605d4e6edc1d 100644
> --- a/arch/arm64/mm/mmap.c
> +++ b/arch/arm64/mm/mmap.c
> @@ -79,9 +79,20 @@ arch_initcall(adjust_protection_map);
>
> pgprot_t vm_get_page_prot(unsigned long vm_flags)
> {
> - pteval_t prot = pgprot_val(protection_map[vm_flags &
> + pteval_t prot;
> +
> + /* If this is a GCS then only interpret VM_WRITE. */
> + if (system_supports_gcs() && (vm_flags & VM_SHADOW_STACK)) {
> + if (vm_flags & VM_WRITE)
> + prot = _PAGE_GCS;
> + else
> + prot = _PAGE_GCS_RO;
> + } else {
> + prot = pgprot_val(protection_map[vm_flags &
> (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]);
> + }
>
> + /* VM_ARM64_BTI on a GCS is rejected in arch_valdiate_flags() */

s/valdiate/validate/

> if (vm_flags & VM_ARM64_BTI)
> prot |= PTE_GP;


--
Thiago

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