Re: [PATCH v2 08/15] efi/libstub: Have efi_kaslr_relocate_kernel() handle extra_size

[Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>]

On Fri,  2 Oct 2026 20:31:45 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:

> There are three possibilities here, each a little different:
> - relocating for kaslr, just request extra_size like the zboot flow does
>   when allocating from EFI
> - in place, attempt to allocate from EFI precisely after Image to
>   confirm nothing weird is there, failing that
> - like any other error with the in place EFI location allocate
>   non-randomly with extra_size included
> 
> Remove the callers' assignments of reserve_size since
> efi_kaslr_relocate_kernel() now does it.
> 
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
A couple of trivial comments.  Otherwise looks good to me.

Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

> diff --git a/drivers/firmware/efi/libstub/kaslr.c b/drivers/firmware/efi/libstub/kaslr.c
> index 4bc963e999eb97..e419f3800af517 100644
> --- a/drivers/firmware/efi/libstub/kaslr.c
> +++ b/drivers/firmware/efi/libstub/kaslr.c

> @@ -125,16 +164,29 @@ efi_status_t efi_kaslr_relocate_kernel(unsigned long *image_addr,
>  	}
>  
>  	if (status != EFI_SUCCESS) {
> -		if (!check_image_region(*image_addr, kernel_memsize)) {
> +		bool image_region_ok =
> +			check_image_region(*image_addr, kernel_memsize);
> +
> +		if (!image_region_ok) {

Why this change?  I don't particularly mind but seems to be churn that isn't
necessarily needed.

>  			efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n");
>  		} else if (IS_ALIGNED(*image_addr, min_kimg_align) &&
> -			   (unsigned long)_end < EFI_ALLOC_LIMIT) {
> -			/*
> -			 * Just execute from wherever we were loaded by the
> -			 * UEFI PE/COFF loader if the placement is suitable.
> -			 */
> -			*reserve_size = 0;
> -			return EFI_SUCCESS;
> +			   (unsigned long)_end + extra_size < EFI_ALLOC_LIMIT) {
> +			if (!extra_size) {
> +				/*
> +				 * Just execute from wherever we were loaded by
> +				 * the UEFI PE/COFF loader if the placement is
> +				 * suitable.
> +				 */
> +				*reserve_size = 0;
> +				return EFI_SUCCESS;
> +			}
> +
> +			status = allocate_image_tail(*image_addr,
> +						     kernel_memsize, extra_size,
> +						     reserve_addr,
> +						     reserve_size);

I'd move reserve_size up a line to group it with reserve_addr.


> +			if (status == EFI_SUCCESS)
> +				return EFI_SUCCESS;
>  		}
>  
>  		status = efi_allocate_pages_aligned(*reserve_size, reserve_addr,
> diff --git a/drivers/firmware/efi/libstub/riscv-stub.c b/drivers/firmware/efi/libstub/riscv-stub.c
> index 725b634c517919..a88b2d275e5bb0 100644
> --- a/drivers/firmware/efi/libstub/riscv-stub.c
> +++ b/drivers/firmware/efi/libstub/riscv-stub.c
> @@ -37,7 +37,6 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
>  	kernel_codesize = __init_text_end - _start;
>  	kernel_memsize = kernel_size + (_end - _edata);
>  	*image_addr = (unsigned long)_start;
> -	*reserve_size = kernel_memsize;
>  
>  	status = efi_kaslr_relocate_kernel(image_addr,
>  					   reserve_addr, reserve_size,