[PATCH v14 09/15] FWU: Add boot time checks as highlighted by the FWU specification

Sughosh Ganu sughosh.ganu at linaro.org
Thu Oct 20 06:35:43 CEST 2022


hi Ilias,

On Thu, 20 Oct 2022 at 01:31, Ilias Apalodimas
<ilias.apalodimas at linaro.org> wrote:
>
> Hi Sughosh,
>
> On Tue, Oct 18, 2022 at 05:13:31PM +0530, Sughosh Ganu wrote:
> > The FWU Multi Bank Update specification requires the Update Agent to
> > carry out certain checks at the time of platform boot. The Update
> > Agent is the component which is responsible for updating the firmware
> > components and maintaining and keeping the metadata in sync.
> >
> > The spec requires that the Update Agent perform the following checks
> > at the time of boot
> > * Sanity check of both the metadata copies maintained by the platform.
> > * Get the boot index passed to U-Boot by the prior stage bootloader
> >   and use this value for metadata bookkeeping.
> > * Check if the system is booting in Trial State. If the system boots
> >   in the Trial State for more than a specified number of boot counts,
> >   change the Active Bank to be booting the platform from.
> >
> > Call these checks through the main loop event at the time of platform
> > boot.
> >
> > Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> > Reviewed-by: Etienne Carriere <etienne.carriere at linaro.org>
> > ---
> > Changes since V13:
> > * Removed the superfluous setting of var_attributes before calling
> >   efi_get_variable_int()
> > * Call fwu_get_dev_mdata() in fwu_trial_state_check() instead of
> >   fwu_boottime_checks()
> >
> >  include/fwu.h         |  13 +++
> >  lib/fwu_updates/fwu.c | 181 +++++++++++++++++++++++++++++++++++++++++-
> >  2 files changed, 193 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/fwu.h b/include/fwu.h
> > index 7d38cb5856..c7b932bc0b 100644
> > --- a/include/fwu.h
> > +++ b/include/fwu.h
> > @@ -345,4 +345,17 @@ int fwu_plat_get_update_index(uint *update_idx);
> >   *
> >   */
> >  void fwu_plat_get_bootidx(uint *boot_idx);
> > +
> > +/**
> > + * fwu_update_checks_pass() - Check if FWU update can be done
> > + *
> > + * Check if the FWU update can be executed. The updates are
> > + * allowed only when the platform is not in Trial State and
> > + * the boot time checks have passed
> > + *
> > + * Return: 1 if OK, 0 on error
> > + *
> > + */
> > +u8 fwu_update_checks_pass(void);
> > +
> >  #endif /* _FWU_H_ */
> > diff --git a/lib/fwu_updates/fwu.c b/lib/fwu_updates/fwu.c
> > index e782dc0176..2016a6d2c1 100644
> > --- a/lib/fwu_updates/fwu.c
> > +++ b/lib/fwu_updates/fwu.c
> > @@ -4,10 +4,19 @@
> >   */
> >
> >  #include <dm.h>
> > +#include <efi.h>
> >  #include <efi_loader.h>
> > +#include <efi_variable.h>
> > +#include <event.h>
> >  #include <fwu.h>
> >  #include <fwu_mdata.h>
> > -#include <log.h>
> > +#include <malloc.h>
> > +
> > +#include <linux/errno.h>
> > +#include <linux/types.h>
> > +
> > +static u8 trial_state;
> > +static u8 boottime_check;
> >
> >  #include <linux/errno.h>
> >  #include <linux/types.h>
> > @@ -44,6 +53,110 @@ static int fwu_get_dev_mdata(struct udevice **dev, struct fwu_mdata *mdata)
> >       return ret;
> >  }
> >
> > +static int trial_counter_update(u16 *trial_state_ctr)
> > +{
> > +     bool delete;
> > +     u32 var_attr;
> > +     efi_status_t status;
> > +     efi_uintn_t var_size;
> > +
> > +     delete = !trial_state_ctr ? true : false;
> > +     var_size = !trial_state_ctr ? 0 : (efi_uintn_t)sizeof(*trial_state_ctr);
> > +     var_attr = !trial_state_ctr ? 0 : EFI_VARIABLE_NON_VOLATILE |
> > +             EFI_VARIABLE_BOOTSERVICE_ACCESS;
> > +     status = efi_set_variable_int(u"TrialStateCtr",
> > +                                   &efi_global_variable_guid,
> > +                                   var_attr,
> > +                                   var_size, trial_state_ctr, false);
> > +
> > +     if ((delete && (status != EFI_NOT_FOUND &&
> > +                     status != EFI_SUCCESS)) ||
> > +         (!delete && status != EFI_SUCCESS))
> > +             return -1;
> > +
> > +     return 0;
> > +}
> > +
> > +static int in_trial_state(struct fwu_mdata *mdata)
> > +{
> > +     u32 i, active_bank;
> > +     struct fwu_image_entry *img_entry;
> > +     struct fwu_image_bank_info *img_bank_info;
> > +
> > +     active_bank = mdata->active_index;
> > +     img_entry = &mdata->img_entry[0];
> > +     for (i = 0; i < CONFIG_FWU_NUM_IMAGES_PER_BANK; i++) {
> > +             img_bank_info = &img_entry[i].img_bank_info[active_bank];
> > +             if (!img_bank_info->accepted) {
> > +                     return 1;
> > +             }
>
> Remove {}

Okay

>
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int fwu_trial_state_check(void)
> > +{
> > +     int ret;
> > +     struct udevice *dev;
> > +     efi_status_t status;
> > +     efi_uintn_t var_size;
> > +     u16 trial_state_ctr;
> > +     struct fwu_mdata mdata = { 0 };
> > +
> > +     ret = fwu_get_dev_mdata(&dev, &mdata);
> > +     if (ret)
> > +             return ret;
> > +
> > +     trial_state = in_trial_state(&mdata);
> > +     if (trial_state) {
> > +             var_size = (efi_uintn_t)sizeof(trial_state_ctr);
> > +             log_info("System booting in Trial State\n");
> > +             status = efi_get_variable_int(u"TrialStateCtr",
> > +                                           &efi_global_variable_guid,
> > +                                           NULL,
> > +                                           &var_size, &trial_state_ctr,
> > +                                           NULL);
> > +             if (status != EFI_SUCCESS) {
> > +                     log_err("Unable to read TrialStateCtr variable\n");
> > +                     ret = -1;
> > +                     goto out;
> > +             }
> > +
> > +             ++trial_state_ctr;
> > +             if (trial_state_ctr > CONFIG_FWU_TRIAL_STATE_CNT) {
> > +                     log_info("Trial State count exceeded. Revert back to previous_active_index\n");
> > +                     ret = fwu_revert_boot_index();
> > +                     if (ret) {
> > +                             log_err("Unable to revert active_index\n");
> > +                             goto out;
> > +                     }
> > +
> > +                     /* Delete the TrialStateCtr variable */
> > +                     ret = trial_counter_update(NULL);
> > +                     if (ret) {
> > +                             log_err("Unable to delete TrialStateCtr variable\n");
> > +                             goto out;
> > +                     }
>
> This is a bit confusing for me.  If the trial_state_ctr we need to goto out
> anyway right?  So why don't we explicitly add a goto out at the end and get
> rid of the else that's following ?

Actually, we don't need the goto statement above, as well as the one
used below, in the else part. I can get rid of it. Personally I feel
that this provides more clarity as to how the code flow is, but I can
get rid of it if you so prefer. Thanks.

-sughosh

>
> > +             } else {
> > +                     ret = trial_counter_update(&trial_state_ctr);
> > +                     if (ret) {
> > +                             log_err("Unable to increment TrialStateCtr variable\n");
> > +                             goto out;
> > +                     }
> > +             }
> > +     } else {
> > +             /* Delete the variable */
> > +             ret = trial_counter_update(NULL);
> > +             if (ret) {
> > +                     log_err("Unable to delete TrialStateCtr variable\n");
> > +             }
> > +     }
> > +
> > +out:
> > +     return ret;
> > +}
> > +
> >  static int fwu_get_image_type_id(u8 *image_index, efi_guid_t *image_type_id)
> >  {
> >       u8 index;
> > @@ -494,3 +607,69 @@ __weak int fwu_plat_get_update_index(uint *update_idx)
> >
> >       return ret;
> >  }
> > +
> > +/**
> > + * fwu_update_checks_pass() - Check if FWU update can be done
> > + *
> > + * Check if the FWU update can be executed. The updates are
> > + * allowed only when the platform is not in Trial State and
> > + * the boot time checks have passed
> > + *
> > + * Return: 1 if OK, 0 on error
> > + *
> > + */
> > +u8 fwu_update_checks_pass(void)
> > +{
> > +     return !trial_state && boottime_check;
> > +}
> > +
> > +static int fwu_boottime_checks(void *ctx, struct event *event)
> > +{
> > +     int ret;
> > +     u32 boot_idx, active_idx;
> > +
> > +     ret = fwu_check_mdata_validity();
> > +     if (ret)
> > +             return 0;
> > +
> > +     /*
> > +      * Get the Boot Index, i.e. the bank from
> > +      * which the platform has booted. This value
> > +      * gets passed from the ealier stage bootloader
> > +      * which booted u-boot, e.g. tf-a. If the
> > +      * boot index is not the same as the
> > +      * active_index read from the FWU metadata,
> > +      * update the active_index.
> > +      */
> > +     fwu_plat_get_bootidx(&boot_idx);
> > +     if (boot_idx >= CONFIG_FWU_NUM_BANKS) {
> > +             log_err("Received incorrect value of boot_index\n");
> > +             return 0;
> > +     }
> > +
> > +     ret = fwu_get_active_index(&active_idx);
> > +     if (ret) {
> > +             log_err("Unable to read active_index\n");
> > +             return 0;
> > +     }
> > +
> > +     if (boot_idx != active_idx) {
> > +             log_info("Boot idx %u is not matching active idx %u, changing active_idx\n",
> > +                      boot_idx, active_idx);
> > +             ret = fwu_set_active_index(boot_idx);
> > +             if (!ret)
> > +                     boottime_check = 1;
> > +
> > +             return 0;
> > +     }
> > +
> > +     if (efi_init_obj_list() != EFI_SUCCESS)
> > +             return 0;
> > +
> > +     ret = fwu_trial_state_check();
> > +     if (!ret)
> > +             boottime_check = 1;
> > +
> > +     return 0;
> > +}
> > +EVENT_SPY(EVT_MAIN_LOOP, fwu_boottime_checks);
> > --
> > 2.34.1
> >
>
> Thanks
> /Ilias


More information about the U-Boot mailing list