[PATCH] kexec: do KEXEC_FILE_LOAD and fallback to KEXEC_LOAD if not supported.

Baoquan He bhe at redhat.com
Thu Feb 22 15:20:43 PST 2018


Hi Michal,

On 02/22/18 at 11:24pm, Michal Suchanek wrote:
> The new KEXEC_FILE_LOAD is preferred in the case the platform supports
> it because it allows kexec in locked down secure boot mode.
> 
> However, some platforms do not support it so fall back to the old
> syscall there.

I didn't read code change, just from patch log, I tend to not agree. There
are two options KEXEC_FILE_LOAD and KEXEC_LOAD, some platforms do not
support, why does some platforms not choose KEXEC_LOAD, the working one?
Why bother to make change in code? I believe there's returned message
telling if KEXEC_FILE_LOAD works or not.

Thanks
Baoquan
> 
> Also provide an option to call the old syscall in case the new syscall
> fails with other reason than ENOSYS.
> 
> Also document the options.
> 
> Signed-off-by: Michal Suchanek <msuchanek at suse.de>
> ---
>  kexec/kexec.8 |  9 +++++++++
>  kexec/kexec.c | 41 +++++++++++++++--------------------------
>  kexec/kexec.h |  2 ++
>  3 files changed, 26 insertions(+), 26 deletions(-)
> 
> diff --git a/kexec/kexec.8 b/kexec/kexec.8
> index e0131b4ea827..7e4df723251d 100644
> --- a/kexec/kexec.8
> +++ b/kexec/kexec.8
> @@ -144,6 +144,15 @@ Load the new kernel for use on panic.
>  Specify that the new kernel is of this
>  .I type.
>  .TP
> +.BI \-s\ (\-\-kexec-file-syscall)
> +Specify that the new KEXEC_FILE_LOAD syscall should be used exclusively.
> +Otherwise KEXEC_FILE_LOAD is tried and when not supported KEXEC_LOAD is used.
> +.I type.
> +.TP
> +.BI \-c\ (\-\-kexec-syscall)
> +Specify that the old KEXEC_LOAD syscall should be used exclusively.
> +.I type.
> +.TP
>  .B \-u\ (\-\-unload)
>  Unload the current
>  .B kexec
> diff --git a/kexec/kexec.c b/kexec/kexec.c
> index cfd837c1b6bb..25328c02b508 100644
> --- a/kexec/kexec.c
> +++ b/kexec/kexec.c
> @@ -1166,7 +1166,7 @@ static int do_kexec_file_load(int fileind, int argc, char **argv,
>  
>  	if (!is_kexec_file_load_implemented()) {
>  		fprintf(stderr, "syscall kexec_file_load not available.\n");
> -		return -1;
> +		return -ENOSYS;
>  	}
>  
>  	if (argc - fileind <= 0) {
> @@ -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_syscall = 0;
>  	int do_status = 0;
>  	void *entry = 0;
>  	char *type = 0;
> @@ -1256,19 +1257,6 @@ int main(int argc, char *argv[])
>  	};
>  	static const char short_options[] = KEXEC_ALL_OPT_STR;
>  
> -	/*
> -	 * First check if --use-kexec-file-syscall is set. That changes lot of
> -	 * things
> -	 */
> -	while ((opt = getopt_long(argc, argv, short_options,
> -				  options, 0)) != -1) {
> -		switch(opt) {
> -		case OPT_KEXEC_FILE_SYSCALL:
> -			do_kexec_file_syscall = 1;
> -			break;
> -		}
> -	}
> -
>  	/* Reset getopt for the next pass. */
>  	opterr = 1;
>  	optind = 1;
> @@ -1310,8 +1298,7 @@ int main(int argc, char *argv[])
>  			do_shutdown = 0;
>  			do_sync = 0;
>  			do_unload = 1;
> -			if (do_kexec_file_syscall)
> -				kexec_file_flags |= KEXEC_FILE_UNLOAD;
> +			kexec_file_flags |= KEXEC_FILE_UNLOAD;
>  			break;
>  		case OPT_EXEC:
>  			do_load = 0;
> @@ -1354,11 +1341,8 @@ int main(int argc, char *argv[])
>  			do_exec = 0;
>  			do_shutdown = 0;
>  			do_sync = 0;
> -			if (do_kexec_file_syscall)
> -				kexec_file_flags |= KEXEC_FILE_ON_CRASH;
> -			else
> -				kexec_flags = KEXEC_ON_CRASH;
> -			break;
> +			kexec_file_flags |= KEXEC_FILE_ON_CRASH;
> +			kexec_flags = KEXEC_ON_CRASH;
>  		case OPT_MEM_MIN:
>  			mem_min = strtoul(optarg, &endptr, 0);
>  			if (*endptr) {
> @@ -1383,7 +1367,12 @@ int main(int argc, char *argv[])
>  			do_reuse_initrd = 1;
>  			break;
>  		case OPT_KEXEC_FILE_SYSCALL:
> -			/* We already parsed it. Nothing to do. */
> +			do_kexec_file_syscall = 1;
> +			do_kexec_syscall = 0;
> +			break;
> +		case OPT_KEXEC_SYSCALL:
> +			do_kexec_file_syscall = 0;
> +			do_kexec_syscall = 1;
>  			break;
>  		case OPT_STATUS:
>  			do_status = 1;
> @@ -1456,16 +1445,16 @@ int main(int argc, char *argv[])
>  		result = k_status(kexec_flags);
>  	}
>  	if (do_unload) {
> -		if (do_kexec_file_syscall)
> +		if (!do_kexec_syscall)
>  			result = kexec_file_unload(kexec_file_flags);
> -		else
> +		if ((result == -ENOSYS) || !do_kexec_file_syscall)
>  			result = k_unload(kexec_flags);
>  	}
>  	if (do_load && (result == 0)) {
> -		if (do_kexec_file_syscall)
> +		if (!do_kexec_syscall)
>  			result = do_kexec_file_load(fileind, argc, argv,
>  						 kexec_file_flags);
> -		else
> +		if ((result == -ENOSYS) || !do_kexec_file_syscall)
>  			result = my_load(type, fileind, argc, argv,
>  						kexec_flags, entry);
>  	}
> diff --git a/kexec/kexec.h b/kexec/kexec.h
> index 26225d2c002a..7abcec796cae 100644
> --- a/kexec/kexec.h
> +++ b/kexec/kexec.h
> @@ -219,6 +219,7 @@ extern int file_types;
>  #define OPT_TYPE		't'
>  #define OPT_PANIC		'p'
>  #define OPT_KEXEC_FILE_SYSCALL	's'
> +#define OPT_KEXEC_SYSCALL	'c'
>  #define OPT_STATUS		'S'
>  #define OPT_MEM_MIN             256
>  #define OPT_MEM_MAX             257
> @@ -246,6 +247,7 @@ extern int file_types;
>  	{ "mem-max",		1, 0, OPT_MEM_MAX }, \
>  	{ "reuseinitrd",	0, 0, OPT_REUSE_INITRD }, \
>  	{ "kexec-file-syscall",	0, 0, OPT_KEXEC_FILE_SYSCALL }, \
> +	{ "kexec-syscall",	0, 0, OPT_KEXEC_SYSCALL }, \
>  	{ "debug",		0, 0, OPT_DEBUG }, \
>  	{ "status",		0, 0, OPT_STATUS }, \
>  	{ "print-ckr-size",     0, 0, OPT_PRINT_CKR_SIZE }, \
> -- 
> 2.13.6
> 
> 
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