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authorHung-Te Lin <hungte@chromium.org>2016-12-29 20:59:37 +0800
committerPatrick Georgi <pgeorgi@google.com>2017-01-03 22:14:42 +0100
commitfe2fc8393632c90b17b9415bdc496d9c38b1f156 (patch)
treef91946404d07b5ca1063e085ee211ff00f2f10ae /src
parent7e1f68c4376b7d6714829cda2e69da4bcd8de2fa (diff)
downloadcoreboot-fe2fc8393632c90b17b9415bdc496d9c38b1f156.tar.xz
vboot: Clear battery cutoff flags when vbnv_cmos loads backup VBNV.
When CONFIG_VBOOT_VBNV_CMOS_BACKUP_TO_FLASH is set, vbnv_cmos will try to load VBNV from flash if the VBNV in CMOS is invalid. This is usually correct, except the case of battery cut-off. CMOS will always be invalid after battery cut-off if there is no RTC battery (or if that is dead). However, in current implementation the backup in flash is only updated in coreboot, while the real battery cutoff (and the clearing of cutoff flags in VBNV) is done in payload (Depthcharge) stage. This will create an endless reboot loop that: 1. crossystem sets battery cutoff flag in VBNV_CMOS then reboot. 2. coreboot backs-up VBNV_CMOS to VBNV_flash. 3. Depthcharge sees cutoff flag in VBNV_CMOS. 4. Depthcharge clears cutoff flag in VBNV_CMOS. 5. Depthcharge performs battery cutoff (CMOS data is lost). 6. (Plug AC adapter) Reboot. 7. Coreboot sees invalid VBNV_CMOS, load backup from VBNV_flash. 8. Jump to 3. As a result, we should always clear battery cutoff flags when loading backups from VBNV_flash. BRANCH=glados,reef BUG=chrome-os-partner:61365,chrome-os-partner:59615 TEST=emerge-reef coreboot bootimage; Change-Id: I3250a3a179a7b0de9c6e401e4a94dcd23920e473 Signed-off-by: Hung-Te Lin <hungte@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/423460 Reviewed-by: Duncan Laurie <dlaurie@google.com> Reviewed-on: https://review.coreboot.org/18008 Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Tested-by: build bot (Jenkins) Reviewed-by: Martin Roth <martinroth@google.com>
Diffstat (limited to 'src')
-rw-r--r--src/vboot/vbnv.c6
-rw-r--r--src/vboot/vbnv.h1
-rw-r--r--src/vboot/vbnv_cmos.c17
-rw-r--r--src/vboot/vbnv_layout.h3
4 files changed, 27 insertions, 0 deletions
diff --git a/src/vboot/vbnv.c b/src/vboot/vbnv.c
index ce6492855d..6537bf04dc 100644
--- a/src/vboot/vbnv.c
+++ b/src/vboot/vbnv.c
@@ -79,6 +79,12 @@ int verify_vbnv(uint8_t *vbnv_copy)
(crc8_vbnv(vbnv_copy, CRC_OFFSET) == vbnv_copy[CRC_OFFSET]);
}
+/* Re-generate VBNV checksum. */
+void regen_vbnv_crc(uint8_t *vbnv_copy)
+{
+ vbnv_copy[CRC_OFFSET] = crc8_vbnv(vbnv_copy, CRC_OFFSET);
+}
+
/*
* Read VBNV data from configured storage backend.
* If VBNV verification fails, reset the vbnv copy.
diff --git a/src/vboot/vbnv.h b/src/vboot/vbnv.h
index 78ca8f66f3..30da6a50c5 100644
--- a/src/vboot/vbnv.h
+++ b/src/vboot/vbnv.h
@@ -22,6 +22,7 @@
void read_vbnv(uint8_t *vbnv_copy);
void save_vbnv(const uint8_t *vbnv_copy);
int verify_vbnv(uint8_t *vbnv_copy);
+void regen_vbnv_crc(uint8_t *vbnv_copy);
int get_recovery_mode_from_vbnv(void);
void set_recovery_mode_into_vbnv(int recovery_reason);
int vboot_wants_oprom(void);
diff --git a/src/vboot/vbnv_cmos.c b/src/vboot/vbnv_cmos.c
index 5eda8e6e50..b7ef3e767f 100644
--- a/src/vboot/vbnv_cmos.c
+++ b/src/vboot/vbnv_cmos.c
@@ -20,6 +20,22 @@
#include <vboot/vbnv.h>
#include <vboot/vbnv_layout.h>
+static void clear_vbnv_battery_cutoff_flag(uint8_t *vbnv_copy)
+{
+ /*
+ * Currently battery cutoff is done in payload stage, which does not
+ * update backup VBNV. And doing battery cutoff will invalidate CMOS.
+ * This means for every reboot after cutoff, read_vbnv_cmos will reload
+ * backup VBNV and try to cutoff again, causing endless reboot loop.
+ * So we should always clear battery cutoff flag from loaded backup.
+ */
+ if (vbnv_copy[MISC_FLAGS_OFFSET] & MISC_FLAGS_BATTERY_CUTOFF_MASK) {
+ printk(BIOS_INFO, "VBNV: Remove battery cut-off request.\n");
+ vbnv_copy[MISC_FLAGS_OFFSET] &= ~MISC_FLAGS_BATTERY_CUTOFF_MASK;
+ regen_vbnv_crc(vbnv_copy);
+ }
+}
+
void read_vbnv_cmos(uint8_t *vbnv_copy)
{
int i;
@@ -35,6 +51,7 @@ void read_vbnv_cmos(uint8_t *vbnv_copy)
read_vbnv_flash(vbnv_copy);
if (verify_vbnv(vbnv_copy)) {
+ clear_vbnv_battery_cutoff_flag(vbnv_copy);
save_vbnv_cmos(vbnv_copy);
printk(BIOS_INFO, "VBNV: Flash backup restored\n");
} else {
diff --git a/src/vboot/vbnv_layout.h b/src/vboot/vbnv_layout.h
index 59acd0c354..1dc01c909a 100644
--- a/src/vboot/vbnv_layout.h
+++ b/src/vboot/vbnv_layout.h
@@ -41,6 +41,9 @@
#define DEV_BOOT_USB_MASK 0x01
#define DEV_BOOT_SIGNED_ONLY_MASK 0x02
+#define MISC_FLAGS_OFFSET 8
+#define MISC_FLAGS_BATTERY_CUTOFF_MASK 0x08
+
#define KERNEL_FIELD_OFFSET 11
#define CRC_OFFSET 15