Re: [PATCH 3/5] efi/zboot: Disentangle efi_remap_image() from efi_cache_sync_image()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Low] efi/zboot: duplicate efi_cache_sync_image() calls after
  decompression
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commit c04555ab5ec2e8a3cceff169f625d907a16b1267
Author: Ard Biesheuvel <ardb@kernel.org>

efi/zboot: Disentangle efi_remap_image() from efi_cache_sync_image()

This commit moves the efi_remap_image() call out of arm64's
efi_cache_sync_image() into a new efi_zboot_remap_image() helper called from
efi_zboot_entry().

> diff --git a/drivers/firmware/efi/libstub/zboot.c b/drivers/firmware/efi/libstub/zboot.c
> index 97ae706c034ad..27f6661253c08 100644
> --- a/drivers/firmware/efi/libstub/zboot.c
> +++ b/drivers/firmware/efi/libstub/zboot.c
> @@ -36,6 +36,26 @@ const struct efi_image_info * __weak zboot_get_image_info(unsigned long image_ba
>  	return NULL;
>  }
>  
> +static efi_status_t efi_zboot_remap_image(const struct efi_image_info *image_info,
> +					  unsigned long image_base,
> +					  unsigned long image_size)
> +{
> +	unsigned long code_size = efistub_get_code_size(image_info);
> +	efi_status_t status;
> +
> +	if (code_size) {
> +		efi_cache_sync_image(image_base, code_size);
> +
> +		status = efi_remap_image(image_base, image_size, code_size);
> +		if (status != EFI_SUCCESS)
> +			return status;
> +	} else {
> +		efi_cache_sync_image(image_base, image_size);
> +	}
> +
> +	return EFI_SUCCESS;
> +}

[Severity: Low]
Does calling efi_cache_sync_image() in efi_zboot_remap_image() duplicate the
cache sync already performed at the end of efi_zboot_decompress()?

0dc1754e16b4 ("efi/libstub: Avoid legacy decompressor zlib/zstd wrappers")
moved efi_cache_sync_image((unsigned long)out, outlen) into
efi_zboot_decompress() in both zboot-decompress-gzip.c and
zboot-decompress-zstd.c.  Because efi_zboot_entry() calls
efi_zboot_remap_image() right after efi_zboot_decompress(),
efi_cache_sync_image() now runs twice back-to-back on every zboot boot, first
over the full allocation and then over code_size.  Should the
efi_cache_sync_image() calls in efi_zboot_decompress() be dropped?

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Sashiko AI review · https://sashiko.dev/#/patchset/20261106141936.2744481-7-ardb+git@google.com?part=3