[1/2] discover/boot: add support for `kexec -s` for kexec_file_load

kexec supports a -s option to perform a kexec_file_load syscall (in
place of a kexec_load). This is triggered through the -s argument to
kexec.

This change adds support for calling kexec with -s. If that fails, we
fall back to -l.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
---
 discover/boot.c | 73 ++++++++++++++++++++++++++++++++-----------------
 1 file changed, 48 insertions(+), 25 deletions(-)

On Tue, 29 Oct 2019 at 09:26, Jeremy Kerr <jk@ozlabs.org> wrote:
>
> kexec supports a -s option to perform a kexec_file_load syscall (in
> place of a kexec_load). This is triggered through the -s argument to
> kexec.
>
> This change adds support for calling kexec with -s. If that fails, we
> fall back to -l.
>
> Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

Reviewed-by: Joel Stanley <joel@jms.id.au>

> ---
>  discover/boot.c | 73 ++++++++++++++++++++++++++++++++-----------------
>  1 file changed, 48 insertions(+), 25 deletions(-)
>
> diff --git a/discover/boot.c b/discover/boot.c
> index 91fc46d..a6b88f0 100644
> --- a/discover/boot.c
> +++ b/discover/boot.c
> @@ -60,14 +60,16 @@ static void __attribute__((format(__printf__, 4, 5))) update_status(
>   */
>  static int kexec_load(struct boot_task *boot_task)
>  {
> +       const char *load_args[] = {"-s", "-l"};
>         struct process *process;
>         char *s_initrd = NULL;
>         char *s_args = NULL;
>         const char *argv[8];
>         char *s_dtb = NULL;
>         const char **p;
> +       char *err_buf;
>         int result;
> -
> +       size_t i;
>
>         boot_task->local_initrd_override = NULL;
>         boot_task->local_dtb_override = NULL;
> @@ -83,7 +85,8 @@ static int kexec_load(struct boot_task *boot_task)
>                                 " verification failure\n", __func__);
>                 }
>
> -               goto abort_kexec;
> +               validate_boot_files_cleanup(boot_task);
> +               return result;
>         }
>
>         const char* local_initrd = (boot_task->local_initrd_override) ?
> @@ -93,20 +96,10 @@ static int kexec_load(struct boot_task *boot_task)
>         const char* local_image = (boot_task->local_image_override) ?
>                 boot_task->local_image_override : boot_task->local_image;
>
> -       process = process_create(boot_task);
> -       if (!process) {
> -               pb_log_fn("failed to create process\n");
> -               return -1;
> -       }
> -
> -       process->path = pb_system_apps.kexec;
> -       process->argv = argv;
> -       process->keep_stdout = true;
> -       process->add_stderr = true;
> -
> +       /* set up process arguments */
>         p = argv;
>         *p++ = pb_system_apps.kexec;    /* 1 */
> -       *p++ = "-l";                    /* 2 */
> +       *p++ = NULL;                    /* 2; modified below */
>
>         if (pb_log_get_debug()) {
>                 *p++ = "--debug";       /* 3 */
> @@ -134,21 +127,51 @@ static int kexec_load(struct boot_task *boot_task)
>         *p++ = local_image;             /* 7 */
>         *p++ = NULL;                    /* 8 */
>
> -       result = process_run_sync(process);
> -       if (result) {
> -               pb_log_fn("failed to run process\n");
> -               goto abort_kexec;
> -       }
> +       err_buf = NULL;
>
> -       result = process->exit_status;
> +       for (i = 0; i < ARRAY_SIZE(load_args); i++) {
> +               /* our first argument is the action: -s or -l */
> +               argv[1] = load_args[i];
>
> -       if (result) {
> -               pb_log_fn("failed: (%d)\n", result);
> -               update_status(boot_task->status_fn, boot_task->status_arg,
> -                               STATUS_ERROR, "%s", process->stdout_buf);
> +               process = process_create(boot_task);
> +               if (!process) {
> +                       result = -1;
> +                       pb_log_fn("failed to create process\n");
> +                       continue;
> +               }
> +
> +               process->path = pb_system_apps.kexec;
> +               process->argv = argv;
> +               process->keep_stdout = true;
> +               process->add_stderr = true;
> +
> +               result = process_run_sync(process);
> +               if (result) {
> +                       pb_log_fn("failed to run process\n");
> +                       continue;
> +               }
> +
> +               if (process_exit_ok(process))
> +                       break;
> +
> +               result = -1;
> +
> +               if (process->stdout_len)
> +                       err_buf = talloc_strndup(boot_task, process->stdout_buf,
> +                                       process->stdout_len);
> +
> +               pb_log_fn("kexec load (%s) failed (rc %d): %s\n", argv[1],
> +                               WEXITSTATUS(process->exit_status),
> +                               err_buf ?: "");
> +
> +               process_release(process);
>         }
>
> -abort_kexec:
> +       if (result)
> +               update_status(boot_task->status_fn, boot_task->status_arg,
> +                               STATUS_ERROR, _("kexec load failed: %s"),
> +                               err_buf ?: "(no output)");
> +
>         validate_boot_files_cleanup(boot_task);
>
>         return result;
> --
> 2.20.1
>
> _______________________________________________
> Petitboot mailing list
> Petitboot@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/petitboot