security/vboot: Use persistent context to read GBB flags

With the persistent vboot context coreboot no longer needs to read GBB
flags from flash itself -- it can just ask vboot for the cached result.
This patch removes the existing GBB code and provides gbb_is_flag_set()
(with a slightly better namespaced name) as a static inline instead.

Change-Id: Ibc3ed0f3fbeb53d630925d47df4dc474b0ed07ee
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37261
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Joel Kitching <kitching@google.com>

src/security/vboot/Makefile.inc

@@ -24,8 +24,6 @@ postcar-y += bootmode.c
 
 verstage-generic-ccopts += -D__VERSTAGE__
 
-ramstage-y += gbb.c
-
 bootblock-y += vbnv.c
 verstage-y += vbnv.c
 romstage-y += vbnv.c

src/security/vboot/gbb.c

@@ -1,80 +0,0 @@
-/*
- * This file is part of the coreboot project.
- *
- * Copyright 2018 Google LLC
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- */
-
-#define NEED_VB20_INTERNALS  /* Peeking into vb2_gbb_header */
-
-#include <commonlib/region.h>
-#include <console/console.h>
-#include <fmap.h>
-#include <security/vboot/gbb.h>
-#include <string.h>
-#include <vb2_api.h>
-
-#define GBB_FMAP_REGION_NAME	"GBB"
-
-/* Copy of GBB header read from boot media. */
-static struct vb2_gbb_header gbb_header;
-
-/*
- * Read "GBB" region from SPI flash to obtain GBB header and validate
- * signature.
- *
- * Return value:
- * Success = 0
- * Error = 1
- */
-static int gbb_init(void)
-{
-	static bool init_done = false;
-	struct region_device gbb_rdev;
-
-	if (init_done != false)
-		return 0;
-
-	if (fmap_locate_area_as_rdev(GBB_FMAP_REGION_NAME, &gbb_rdev))
-		return 1;
-
-	if (rdev_readat(&gbb_rdev, &gbb_header, 0,
-			sizeof(struct vb2_gbb_header)) !=
-	    sizeof(struct vb2_gbb_header)) {
-		printk(BIOS_ERR, "%s: Failure to read GBB header!\n", __func__);
-		return 1;
-	}
-
-	if (memcmp(gbb_header.signature, VB2_GBB_SIGNATURE,
-		   VB2_GBB_SIGNATURE_SIZE)) {
-		printk(BIOS_ERR, "%s: Signature check failed!\n", __func__);
-		return 1;
-	}
-
-	init_done = true;
-	return 0;
-}
-
-uint32_t gbb_get_flags(void)
-{
-	if (gbb_init()) {
-		printk(BIOS_ERR,
-		       "%s: Failure to initialize GBB. Returning flags as 0!\n",
-		       __func__);
-		return 0;
-	}
-	return gbb_header.flags;
-}
-
-bool gbb_is_flag_set(uint32_t flag)
-{
-	return !!(gbb_get_flags() & flag);
-}

src/security/vboot/gbb.h

@@ -1,39 +0,0 @@
-/*
- * This file is part of the coreboot project.
- *
- * Copyright 2018 Google LLC
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- */
-
-#ifndef __SECURITY_VBOOT_GBB_H__
-#define __SECURITY_VBOOT_GBB_H__
-
-#include <stdint.h>
-
-/* In order to use VB2_GBB_FLAG_* macros from vboot, include vb2_api.h. */
-
-/*
- * Read flags field from GBB header.
- * Return value:
- * Success: 32-bit unsigned integer representing flags field from GBB header.
- * Error  : 0
- */
-uint32_t gbb_get_flags(void);
-
-/*
- * Check if given flag is set in the flags field in GBB header.
- * Return value:
- * true: Flag is set.
- * false: Flag is not set or failure to read GBB flags.
- */
-bool gbb_is_flag_set(uint32_t flag);
-
-#endif /* __SECURITY_VBOOT_GBB_H__ */

src/security/vboot/misc.h

@@ -49,6 +49,17 @@ static inline int vboot_is_firmware_slot_a(const struct vb2_context *ctx)
 	return !(ctx->flags & VB2_CONTEXT_FW_SLOT_B);
 }
 
+/*
+ * Check if given flag is set in the flags field in GBB header.
+ * Return value:
+ * true: Flag is set.
+ * false: Flag is not set.
+ */
+static inline bool vboot_is_gbb_flag_set(enum vb2_gbb_flag flag)
+{
+	return !!(vb2api_gbb_get_flags(vboot_get_context()) & flag);
+}
+
 /*
  * Locates firmware as a region device. Returns 0 on success, -1 on failure.
  */

src/security/vboot/vboot_common.c

@@ -19,7 +19,7 @@
 #include <fmap.h>
 #include <reset.h>
 #include <stddef.h>
-#include <security/vboot/gbb.h>
+#include <security/vboot/misc.h>
 #include <security/vboot/vboot_common.h>
 #include <security/vboot/vbnv.h>
 #include <vb2_api.h>
@@ -31,7 +31,7 @@ int vboot_can_enable_udc(void)
 	if (!vboot_developer_mode_enabled())
 		return 0;
 	/* Enable if GBB flag is set */
-	if (gbb_is_flag_set(VB2_GBB_FLAG_ENABLE_UDC))
+	if (vboot_is_gbb_flag_set(VB2_GBB_FLAG_ENABLE_UDC))
 		return 1;
 	/* Enable if VBNV flag is set */
 	if (vbnv_udc_enable_flag())