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authorFurquan Shaikh <furquan@google.com>2016-07-25 11:48:03 -0700
committerFurquan Shaikh <furquan@google.com>2016-07-28 00:36:00 +0200
commit2a12e2e8da2477d97b8774babd1a74dda65d11a0 (patch)
treec8bbdc94b777269dcdaa2c5070c61432b1001986 /src/vboot/vbnv_flash.c
parentaf8ef2a810f97b762d30de2b6f30d6ffefa0ae0e (diff)
downloadcoreboot-2a12e2e8da2477d97b8774babd1a74dda65d11a0.tar.xz
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>
Diffstat (limited to 'src/vboot/vbnv_flash.c')
-rw-r--r--src/vboot/vbnv_flash.c228
1 files changed, 228 insertions, 0 deletions
diff --git a/src/vboot/vbnv_flash.c b/src/vboot/vbnv_flash.c
new file mode 100644
index 0000000000..8b60be2b72
--- /dev/null
+++ b/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");
+ }
+}