Refactor rollback interface for LoadKernel(), LoadFirmware().

firmware/include/rollback_index.h

 /* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
  * Functions for querying, manipulating and locking rollback indices
  * stored in the TPM NVRAM.
  */
 
 #ifndef VBOOT_REFERENCE_ROLLBACK_INDEX_H_
 #define VBOOT_REFERENCE_ROLLBACK_INDEX_H_
@@ skipping 25 matching lines @@
 #define DEVELOPER_MODE_NV_INDEX         0x1006
 
 /* Unique ID to detect kernel space redefinition */
 #define KERNEL_SPACE_UID "GRWL"        /* unique ID with secret meaning */
 #define KERNEL_SPACE_UID_SIZE (sizeof(KERNEL_SPACE_UID) - 1)
 #define KERNEL_SPACE_INIT_DATA ((uint8_t*) "\0\0\0\0" KERNEL_SPACE_UID)
 #define KERNEL_SPACE_SIZE (sizeof(uint32_t) + KERNEL_SPACE_UID_SIZE)
 
 /* All functions return TPM_SUCCESS (zero) if successful, non-zero if error */
 
+
+/*
+
+Call from LoadFirmware()
+  Normal or developer mode (not recovery)
+  Wants firmware versions
+  Must send in developer flag
+
+  RollbackFirmwareSetup(IN devmode, OUT firmware versions)
+  (maybe) RollbackFirmwareWrite()
+  RollbackFirmwareLock()
+
+Call from LoadKernel()
+
+  RollbackKernelRecovery(IN devmode)
+     (implies LockFirmwareVersions() inside the setup)
+
+  RollbackKernelRead(OUT kernel versions)
+  (maybe) RollbackKernelWrite()
+  RollbackKernelLock()
+
+  Any mode
+    If recovery mode, this is the first time we've been called
+      Must send in developer flag
+    If not recovery mode, wants kernel versions
+  Must send in developer and recovery flags
+*/
+
+/* These functions are callable from LoadFirmware().  They cannot use
+ * global variables. */
+/* Setup must be called. */
+uint32_t RollbackFirmwareSetup(int developer_mode,
+                               uint16_t* key_version, uint16_t* version);
+/* Write may be called if the versions change */
+uint32_t RollbackFirmwareWrite(uint16_t key_version, uint16_t version);
+/* Lock must be called */
+uint32_t RollbackFirmwareLock(void);
+
+/* These functions are callable from LoadKernel().  They may use global
+ * variables. */
+/* Recovery may be called.  If it is, this is the first time a
+ * rollback function has been called this boot, so it needs to know if
+ * we're in developer mode. */
+uint32_t RollbackKernelRecovery(int developer_mode);
+/* Read and write may be called if not in developer mode.  If called in
+ * recovery mode, these are ignored and/or return 0 versions. */
+uint32_t RollbackKernelRead(uint16_t* key_version, uint16_t* version);
+uint32_t RollbackKernelWrite(uint16_t key_version, uint16_t version);
+/* Lock must be called.  Internally, it's ignored in recovery mode. */
+uint32_t RollbackKernelLock(void);
+
+
 /* SetupTPM is called on boot and on starting the RW firmware, passing the
  * appripriate MODE and DEVELOPER_FLAG parameters.  MODE can be one of
  * RO_RECOVERY_MODE, RO_NORMAL_MODE, RW_NORMAL_MODE.  DEVELOPER_FLAG is 1 when
  * the developer switch is ON, 0 otherwise.
  *
  * If SetupTPM returns TPM_SUCCESS, the caller may proceed.  If it returns
  * TPM_E_MUST_REBOOT, the caller must reboot in the current mode.  For all
  * other return values, the caller must reboot in recovery mode.
  *
  * This function has many side effects on the TPM state.  In particular, when
  * called with mode = RECOVERY_MODE, it locks the firmware versions before
  * returning.  In all other cases, the caller is responsible for locking the
  * firmware versions once it decides it doesn't need to update them.
  */
 uint32_t SetupTPM(int mode, int developer_flag);
 uint32_t GetStoredVersions(int type, uint16_t* key_version, uint16_t* version);
 uint32_t WriteStoredVersions(int type, uint16_t key_version, uint16_t version);
 uint32_t LockFirmwareVersions(void);
 uint32_t LockKernelVersionsByLockingPP(void);
 
 #endif  /* VBOOT_REFERENCE_ROLLBACK_INDEX_H_ */