vboot: Separate vboot from chromeos

VBOOT_VERIFY_FIRMWARE should be independent of CHROMEOS. This allows use
of verified boot library without having to stick to CHROMEOS.

BUG=chrome-os-partner:55639

Change-Id: Ia2c328712caedd230ab295b8a613e3c1ed1532d9
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/15867
Tested-by: build bot (Jenkins)
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>

src/vboot/vbnv_flash.c

@@ -0,0 +1,228 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2014 The ChromiumOS Authors.  All rights reserved.
+ *
+ * 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.
+ */
+
+#include <arch/early_variables.h>
+#include <assert.h>
+#include <commonlib/region.h>
+#include <console/console.h>
+#include <spi_flash.h>
+#include <string.h>
+#include <vb2_api.h>
+#include <vboot_nvstorage.h>
+#include <vboot/vboot_common.h>
+#include <vboot/vbnv.h>
+#include <vboot/vbnv_layout.h>
+
+#define BLOB_SIZE VB2_NVDATA_SIZE
+
+struct vbnv_flash_ctx {
+	/* VBNV flash is initialized */
+	int initialized;
+
+	/* Offset of the current nvdata in SPI flash */
+	int blob_offset;
+
+	/* Offset of the topmost nvdata blob in SPI flash */
+	int top_offset;
+
+	/* SPI flash handler used when saving data */
+	struct spi_flash *flash;
+
+	/* FMAP descriptor of the NVRAM area */
+	struct region_device region;
+
+	/* Cache of the current nvdata */
+	uint8_t cache[BLOB_SIZE];
+};
+static struct vbnv_flash_ctx vbnv_flash CAR_GLOBAL;
+
+/*
+ * This code assumes that flash is erased to 1-bits, and write operations can
+ * only change 1-bits to 0-bits. So if the new contents only change 1-bits to
+ * 0-bits, we can reuse the current blob.
+ */
+static inline uint8_t erase_value(void)
+{
+	return 0xff;
+}
+
+static inline int can_overwrite(uint8_t current, uint8_t new)
+{
+	return (current & new) == new;
+}
+
+static int init_vbnv(void)
+{
+	struct vbnv_flash_ctx *ctx = car_get_var_ptr(&vbnv_flash);
+	uint8_t buf[BLOB_SIZE];
+	uint8_t empty_blob[BLOB_SIZE];
+	int offset;
+	int i;
+
+	if (vboot_named_region_device("RW_NVRAM", &ctx->region) ||
+	    region_device_sz(&ctx->region) < BLOB_SIZE) {
+		printk(BIOS_ERR, "%s: failed to locate NVRAM\n", __func__);
+		return 1;
+	}
+
+	/* Prepare an empty blob to compare against. */
+	for (i = 0; i < BLOB_SIZE; i++)
+		empty_blob[i] = erase_value();
+
+	offset = 0;
+	ctx->top_offset = region_device_sz(&ctx->region) - BLOB_SIZE;
+
+	/*
+	 * after the loop, offset is supposed to point the blob right before
+	 * the first empty blob, the last blob in the nvram if there is no
+	 * empty blob, or the base of the region if the nvram has never been
+	 * used.
+	 */
+	for (i = 0; i <= ctx->top_offset; i += BLOB_SIZE) {
+		if (rdev_readat(&ctx->region, buf, i, BLOB_SIZE) < 0) {
+			printk(BIOS_ERR, "failed to read nvdata\n");
+			return 1;
+		}
+		if (!memcmp(buf, empty_blob, BLOB_SIZE))
+			break;
+		offset = i;
+	}
+
+	/* reread the nvdata and write it to the cache */
+	if (rdev_readat(&ctx->region, ctx->cache, offset, BLOB_SIZE) < 0) {
+		printk(BIOS_ERR, "failed to read nvdata\n");
+		return 1;
+	}
+
+	ctx->blob_offset = offset;
+	ctx->initialized = 1;
+
+	return 0;
+}
+
+static void vbnv_is_erasable(void)
+{
+	/*
+	 * We check whether the region is aligned or not in advance to ensure
+	 * we can erase the region when it's all used up.
+	 *
+	 * The region offset & size are determined by fmap.dts yet the check can
+	 * be confidently done only by the spi flash driver. We use the same
+	 * check as the one used by spi_flash_cmd_erase, which happens to be
+	 * common to all the spi flash parts we support.
+	 *
+	 * TODO: Check by calling can_erase implemented by each spi flash driver
+	 */
+	struct vbnv_flash_ctx *ctx = car_get_var_ptr(&vbnv_flash);
+
+	assert(!(region_device_offset(&ctx->region) % ctx->flash->sector_size));
+	assert(!(region_device_sz(&ctx->region) % ctx->flash->sector_size));
+}
+
+static int vbnv_flash_probe(void)
+{
+	struct vbnv_flash_ctx *ctx = car_get_var_ptr(&vbnv_flash);
+
+	if (!ctx->flash) {
+		ctx->flash = spi_flash_probe(CONFIG_BOOT_MEDIA_SPI_BUS, 0);
+		if (!ctx->flash) {
+			printk(BIOS_ERR, "failed to probe spi flash\n");
+			return 1;
+		}
+		/*
+		 * Called here instead of init_vbnv to reduce impact on boot
+		 * speed.
+		 */
+		vbnv_is_erasable();
+	}
+
+	/*
+	 * Handle the case where spi_flash_probe returns a CAR_GLOBAL
+	 * in early execution on x86 but then later is moved to RAM.
+	 */
+	ctx->flash = car_get_var_ptr(ctx->flash);
+
+	return 0;
+}
+
+static int erase_nvram(void)
+{
+	struct vbnv_flash_ctx *ctx = car_get_var_ptr(&vbnv_flash);
+
+	if (vbnv_flash_probe())
+		return 1;
+
+	if (ctx->flash->erase(ctx->flash, region_device_offset(&ctx->region),
+			      region_device_sz(&ctx->region))) {
+		printk(BIOS_ERR, "failed to erase nvram\n");
+		return 1;
+	}
+
+	printk(BIOS_INFO, "nvram is cleared\n");
+	return 0;
+}
+
+void read_vbnv_flash(uint8_t *vbnv_copy)
+{
+	struct vbnv_flash_ctx *ctx = car_get_var_ptr(&vbnv_flash);
+
+	if (!ctx->initialized)
+		if (init_vbnv())
+			return;  /* error */
+
+	memcpy(vbnv_copy, ctx->cache, BLOB_SIZE);
+}
+
+void save_vbnv_flash(const uint8_t *vbnv_copy)
+{
+	struct vbnv_flash_ctx *ctx = car_get_var_ptr(&vbnv_flash);
+	int new_offset;
+	int i;
+
+	if (!ctx->initialized)
+		if (init_vbnv())
+			return;  /* error */
+
+	/* Bail out if there have been no changes. */
+	if (!memcmp(vbnv_copy, ctx->cache, BLOB_SIZE))
+		return;
+
+	new_offset = ctx->blob_offset;
+
+	/* See if we can overwrite the current blob with the new one */
+	for (i = 0; i < BLOB_SIZE; i++) {
+		if (!can_overwrite(ctx->cache[i], vbnv_copy[i])) {
+			/* unable to overwrite. need to use the next blob */
+			new_offset += BLOB_SIZE;
+			if (new_offset > ctx->top_offset) {
+				if (erase_nvram())
+					return;  /* error */
+				new_offset = 0;
+			}
+			break;
+		}
+	}
+
+	if (!vbnv_flash_probe() &&
+	    !ctx->flash->write(ctx->flash,
+			       region_device_offset(&ctx->region) + new_offset,
+			       BLOB_SIZE, vbnv_copy)) {
+		/* write was successful. safely move pointer forward */
+		ctx->blob_offset = new_offset;
+		memcpy(ctx->cache, vbnv_copy, BLOB_SIZE);
+	} else {
+		printk(BIOS_ERR, "failed to save nvdata\n");
+	}
+}