[PATCH 4/5] kexec: fallback to KEXEC_LOAD when KEXEC_FILE_LOAD is not supported.

[Simon Horman]

On Mon, Feb 26, 2018 at 01:00:37PM +0100, Michal Suchanek wrote:
> Not all architectures implement KEXEC_FILE_LOAD. However, on some
> archiectures KEXEC_FILE_LOAD is required when secure boot is enabled in
> locked-down mode. Previously users had to select the KEXEC_FILE_LOAD
> syscall with undocumented -s option. However, if they did pass the
> option kexec would fail on architectures that do not support it.
> 
> When no option is passed to select one syscall or the other try
> KEXEC_FILE_LOAD and fall back to KEXEC_LOAD when not suported.

Has there been a release of kexec-tools with things arranged they
way they currently are?

Can we document this behaviour and the related undocumented options?

> Signed-off-by: Michal Suchanek <msuchanek at suse.de>
> ---
>  kexec/kexec.c | 43 +++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 39 insertions(+), 4 deletions(-)
> 
> diff --git a/kexec/kexec.c b/kexec/kexec.c
> index a95cfb473d6b..14f56e466a95 100644
> --- a/kexec/kexec.c
> +++ b/kexec/kexec.c
> @@ -1243,6 +1243,7 @@ int main(int argc, char *argv[])
>  	int do_unload = 0;
>  	int do_reuse_initrd = 0;
>  	int do_kexec_file_syscall = 0;
> +	int do_kexec_fallback = 1;
>  	int do_status = 0;
>  	void *entry = 0;
>  	char *type = 0;
> @@ -1367,9 +1368,11 @@ int main(int argc, char *argv[])
>  			break;
>  		case OPT_KEXEC_FILE_SYSCALL:
>  			do_kexec_file_syscall = 1;
> +			do_kexec_fallback = 0;
>  			break;
>  		case OPT_KEXEC_SYSCALL:
>  			do_kexec_file_syscall = 0;
> +			do_kexec_fallback = 0;
>  			break;
>  		case OPT_STATUS:
>  			do_status = 1;
> @@ -1442,16 +1445,48 @@ int main(int argc, char *argv[])
>  		result = k_status(kexec_flags);
>  	}
>  	if (do_unload) {
> -		if (do_kexec_file_syscall)
> +		if (do_kexec_file_syscall) {
>  			result = kexec_file_unload(kexec_file_flags);
> -		else
> +			if ((result == -ENOSYS) && do_kexec_fallback)
> +				do_kexec_file_syscall = 0;
> +		}
> +		if (!do_kexec_file_syscall)
>  			result = k_unload(kexec_flags);
>  	}
>  	if (do_load && (result == 0)) {
> -		if (do_kexec_file_syscall)
> +		if (do_kexec_file_syscall) {
>  			result = do_kexec_file_load(fileind, argc, argv,
>  						 kexec_file_flags);
> -		else
> +			if (do_kexec_fallback) switch (result) {
> +				/*
> +				 * Something failed with signature verification.
> +				 * Reject the image.
> +				 */
> +				case -ELIBBAD:
> +				case -EKEYREJECTED:
> +				case -ENOPKG:
> +				case -ENOKEY:
> +				case -EBADMSG:
> +				case -EMSGSIZE:
> +				case -ENOTSUPP:
> +					/*
> +					 * By default reject or do nothing if
> +					 * succeded
> +					 */
> +				default: break;
> +					/*
> +					 * Parsing image or other options failed
> +					 * The image may be invalid or image
> +					 * type may not supported by kernel so
> +					 * retry parsing in kexec-tools.
> +					 */
> +				case -EINVAL:
> +				case -ENOEXEC:
> +					do_kexec_file_syscall = 0;
> +					break;
> +			}
> +		}
> +		if (!do_kexec_file_syscall)

How about:

	if (do_kexec_file_syscall) {
		result = ...;
		/* Comment */
		if (do_kexec_fallback &&
		    (result == -EINVAL || result == -ENOEXEC))
			do_kexec_file_syscall = 0;
	}
	if (!do_kexec_file_syscall)
		result = ...;



>  			result = my_load(type, fileind, argc, argv,
>  						kexec_flags, entry);
>  	}
> -- 
> 2.13.6
>