[PATCH v5 08/23] FWU: Add boot time checks as highlighted by the FWU specification

Sughosh Ganu
2022-06-09T12:32:19Z

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.

Add these checks in the board initialisation sequence, invoked after
relocation.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
---
common/board_r.c | 5 ++
include/fwu.h | 3 +
lib/fwu_updates/fwu.c | 170 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 178 insertions(+)
create mode 100644 lib/fwu_updates/fwu.c

diff --git a/common/board_r.c b/common/board_r.c
index 6f4aca2077..33a600715d 100644
--- a/common/board_r.c
+++ b/common/board_r.c
@@ -15,6 +15,7 @@
#include <cpu_func.h>
#include <exports.h>
#include <flash.h>
+#include <fwu.h>
#include <hang.h>
#include <image.h>
#include <irq_func.h>
@@ -797,6 +798,10 @@ static init_fnc_t init_sequence_r[] = {
#if defined(CONFIG_PRAM)
initr_mem,
#endif
+
+#ifdef CONFIG_FWU_MULTI_BANK_UPDATE
+ fwu_boottime_checks,
+#endif
run_main_loop,
};

diff --git a/include/fwu.h b/include/fwu.h
index 41774ff9e2..8fbd91b463 100644
--- a/include/fwu.h
+++ b/include/fwu.h
@@ -33,6 +33,9 @@ struct fwu_mdata_ops {
EFI_GUID(0x8a7a84a0, 0x8387, 0x40f6, 0xab, 0x41, \
0xa8, 0xb9, 0xa5, 0xa6, 0x0d, 0x23)

+int fwu_boottime_checks(void);
+u8 fwu_update_checks_pass(void);
+
int fwu_get_mdata(struct fwu_mdata **mdata);
int fwu_update_mdata(struct fwu_mdata *mdata);
int fwu_get_active_index(u32 *active_idx);
diff --git a/lib/fwu_updates/fwu.c b/lib/fwu_updates/fwu.c
new file mode 100644
index 0000000000..af884439fb
--- /dev/null
+++ b/lib/fwu_updates/fwu.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2022, Linaro Limited
+ */
+
+#include <dm.h>
+#include <efi.h>
+#include <efi_loader.h>
+#include <efi_variable.h>
+#include <fwu.h>
+#include <fwu_mdata.h>
+#include <malloc.h>
+
+#include <linux/errno.h>
+#include <linux/types.h>
+
+static u8 trial_state;
+static u8 boottime_check;
+
+static int fwu_trial_state_check(void)
+{
+ int ret, i;
+ efi_status_t status;
+ efi_uintn_t var_size;
+ u16 trial_state_ctr;
+ u32 nimages, active_bank, var_attributes, active_idx;
+ struct fwu_mdata *mdata = NULL;
+ struct fwu_image_entry *img_entry;
+ struct fwu_image_bank_info *img_bank_info;
+
+ ret = fwu_get_mdata(&mdata);
+ if (ret)
+ return ret;
+
+ ret = 0;
+ nimages = CONFIG_FWU_NUM_IMAGES_PER_BANK;
+ active_bank = mdata->active_index;
+ img_entry = &mdata->img_entry[0];
+ for (i = 0; i < nimages; i++) {
+ img_bank_info = &img_entry[i].img_bank_info[active_bank];
+ if (!img_bank_info->accepted) {
+ trial_state = 1;
+ break;
+ }
+ }
+
+ if (trial_state) {
+ var_size = (efi_uintn_t)sizeof(trial_state_ctr);
+ log_info("System booting in Trial State\n");
+ var_attributes = EFI_VARIABLE_NON_VOLATILE |
+ EFI_VARIABLE_BOOTSERVICE_ACCESS;
+ status = efi_get_variable_int(L"TrialStateCtr",
+ &efi_global_variable_guid,
+ &var_attributes,
+ &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");
+ active_idx = mdata->active_index;
+ ret = fwu_revert_boot_index();
+ if (ret) {
+ log_err("Unable to revert active_index\n");
+ goto out;
+ }
+
+ trial_state_ctr = 0;
+ status = efi_set_variable_int(L"TrialStateCtr",
+ &efi_global_variable_guid,
+ var_attributes,
+ 0,
+ &trial_state_ctr, false);
+ if (status != EFI_SUCCESS) {
+ log_err("Unable to clear TrialStateCtr variable\n");
+ ret = -1;
+ goto out;
+ }
+ } else {
+ status = efi_set_variable_int(L"TrialStateCtr",
+ &efi_global_variable_guid,
+ var_attributes,
+ var_size,
+ &trial_state_ctr, false);
+ if (status != EFI_SUCCESS) {
+ log_err("Unable to increment TrialStateCtr variable\n");
+ ret = -1;
+ goto out;
+ }
+ }
+ } else {
+ trial_state_ctr = 0;
+ status = efi_set_variable_int(L"TrialStateCtr",
+ &efi_global_variable_guid,
+ 0,
+ 0, &trial_state_ctr,
+ NULL);
+ }
+
+out:
+ free(mdata);
+ return ret;
+}
+
+u8 fwu_update_checks_pass(void)
+{
+ return !trial_state && boottime_check;
+}
+
+int fwu_boottime_checks(void)
+{
+ int ret;
+ struct udevice *dev;
+ u32 boot_idx, active_idx;
+
+ if (uclass_get_device(UCLASS_FWU_MDATA, 0, &dev) || !dev) {
+ log_err("FWU Metadata device not found\n");
+ return 0;
+ }
+
+ ret = fwu_mdata_check();
+ 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_update_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;
+}
--
2.25.1