[PATCH v4 15/29] arm64: handle PKEY/POE faults

[Catalin Marinas]

On Fri, May 03, 2024 at 02:01:33PM +0100, Joey Gouly wrote:
> @@ -529,6 +547,8 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
>  	unsigned int mm_flags = FAULT_FLAG_DEFAULT;
>  	unsigned long addr = untagged_addr(far);
>  	struct vm_area_struct *vma;
> +	bool pkey_fault = false;
> +	int pkey = -1;
>  
>  	if (kprobe_page_fault(regs, esr))
>  		return 0;
> @@ -590,6 +610,12 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
>  		vma_end_read(vma);
>  		goto lock_mmap;
>  	}
> +
> +	if (fault_from_pkey(esr, vma, mm_flags)) {
> +		vma_end_read(vma);
> +		goto lock_mmap;
> +	}
> +
>  	fault = handle_mm_fault(vma, addr, mm_flags | FAULT_FLAG_VMA_LOCK, regs);
>  	if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
>  		vma_end_read(vma);
> @@ -617,6 +643,11 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
>  		goto done;
>  	}
>  
> +	if (fault_from_pkey(esr, vma, mm_flags)) {
> +		pkey_fault = true;
> +		pkey = vma_pkey(vma);
> +	}

I was wondering if we actually need to test this again. We know the
fault was from a pkey already above but I guess it matches what we do
with the vma->vm_flags check in case it races with some mprotect() call.

> +
>  	fault = __do_page_fault(mm, vma, addr, mm_flags, vm_flags, regs);

You'll need to rebase this on 6.10-rcX since this function disappeared.

Otherwise the patch looks fine.

Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>