futility: updater: add new quirk 'clear_mrc_data'

For devices with some memory training data that is not compatible with
the new flashed firmware (and can't be automatically detected by the new
firmware), we need a way to easily wipe out the existing memory training
data to enforce a retraining at the next boot. This usually happens when
repairing a device (with non-qualified firmware) and should never happen
in the OTA.

BUG=b:255617349
TEST=make; run test
BRANCH=None

Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Change-Id: I92befefa6be59da10ca7572e7849ef905f184a5f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/4018593
Reviewed-by: Yu-Ping Wu <yupingso@chromium.org>
Tested-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Commit-Queue: Yu-Ping Wu <yupingso@chromium.org>

5 files changed, 77 insertions, 17 deletions

diff --git a/futility/updater.c b/futility/updater.c
index e6ba3443..c0a500fc 100644
--- a/futility/updater.c
+++ b/futility/updater.c
@@ -581,23 +581,6 @@ static int section_needs_update(const struct firmware_image *image_from,
 }
 
 /*
- * Returns true if the write protection is enabled on current system.
- */
-static int is_write_protection_enabled(struct updater_config *cfg)
-{
-	/* Default to enabled. */
-	int wp = get_system_property(SYS_PROP_WP_HW, cfg);
-	if (wp == WP_DISABLED)
-		return wp;
-	/* For error or enabled, check WP SW. */
-	wp = get_system_property(SYS_PROP_WP_SW, cfg);
-	/* Consider all errors as enabled. */
-	if (wp != WP_DISABLED)
-		return WP_ENABLED;
-	return wp;
-}
-
-/*
  * Checks if the given firmware images are compatible with current platform.
  * In current implementation (following Chrome OS style), we assume the platform
  * is identical to the name before a dot (.) in firmware version.
@@ -1227,6 +1210,9 @@ enum updater_error_codes update_firmware(struct updater_config *cfg)
 	if (try_apply_quirk(QUIRK_EVE_SMM_STORE, cfg))
 		return UPDATE_ERR_INVALID_IMAGE;
 
+	if (try_apply_quirk(QUIRK_CLEAR_MRC_DATA, cfg))
+		return UPDATE_ERR_SYSTEM_IMAGE;
+
 	if (debugging_enabled)
 		print_system_properties(cfg);
 
diff --git a/futility/updater.h b/futility/updater.h
index 768beece..cedeb302 100644
--- a/futility/updater.h
+++ b/futility/updater.h
@@ -51,6 +51,7 @@ enum quirk_types {
 	QUIRK_NO_VERIFY,
 	QUIRK_EXTRA_RETRIES,
 	QUIRK_EXTERNAL_FLASHROM,
+	QUIRK_CLEAR_MRC_DATA,
 	QUIRK_MAX,
 };
 
diff --git a/futility/updater_quirks.c b/futility/updater_quirks.c
index dab86ec8..4975997a 100644
--- a/futility/updater_quirks.c
+++ b/futility/updater_quirks.c
@@ -424,6 +424,52 @@ static int quirk_preserve_me(struct updater_config *cfg)
 	return 1;
 }
 
+static int quirk_clear_mrc_data(struct updater_config *cfg)
+{
+	struct firmware_section section;
+	struct firmware_image *image = &cfg->image_current;
+	int i, count = 0;
+	int flash_now = 0;
+
+	/*
+	 * Devices with multiple MRC caches (RECOVERY, RW, RW_VAR) will have the
+	 * UNIFIED_MRC_CACHE; and devices with single RW cache will only have
+	 * RW_MRC_CACHE (for example MediaTek devices).
+	 */
+	const char * const mrc_names[] = {
+		"UNIFIED_MRC_CACHE",
+		"RW_MRC_CACHE",
+	};
+
+	if (is_write_protection_enabled(cfg) || cfg->try_update)
+		flash_now = 1;
+
+	for (i = 0; i < ARRAY_SIZE(mrc_names); i++) {
+		const char *name = mrc_names[i];
+		const char *write_names[2] = {0};
+
+		find_firmware_section(&section, image, name);
+		if (!section.size)
+			continue;
+
+		WARN("Wiping memory training data: %s\n", name);
+		memset(section.data, 0xff, section.size);
+		if (flash_now) {
+			write_names[0] = name;
+			write_system_firmware(cfg, image, write_names);
+		}
+		count++;
+		break;
+	}
+
+	if (count)
+		WARN("Next boot will take a few mins for memory training.\n");
+	else
+		ERROR("No known memory training data in the firmware image.\n");
+
+	return 0;
+}
+
 /*
  * Disable checking platform compatibility.
  */
@@ -522,6 +568,11 @@ void updater_register_quirks(struct updater_config *cfg)
 	quirks->name = "external_flashrom";
 	quirks->help = "Use external flashrom to access the system firmware.";
 	quirks->apply = NULL;  /* Simple config. */
+
+	quirks = &cfg->quirks[QUIRK_CLEAR_MRC_DATA];
+	quirks->name = "clear_mrc_data";
+	quirks->help = "b/255617349: Clear memory training data (MRC).";
+	quirks->apply = quirk_clear_mrc_data;
 }
 
 /*
diff --git a/futility/updater_utils.c b/futility/updater_utils.c
index 8895c094..cb7ac604 100644
--- a/futility/updater_utils.c
+++ b/futility/updater_utils.c
@@ -359,6 +359,23 @@ const struct vb2_gbb_header *find_gbb(const struct firmware_image *image)
 }
 
 /*
+ * Returns true if the write protection is enabled on current system.
+ */
+int is_write_protection_enabled(struct updater_config *cfg)
+{
+	/* Default to enabled. */
+	int wp = get_system_property(SYS_PROP_WP_HW, cfg);
+	if (wp == WP_DISABLED)
+		return wp;
+	/* For error or enabled, check WP SW. */
+	wp = get_system_property(SYS_PROP_WP_SW, cfg);
+	/* Consider all errors as enabled. */
+	if (wp != WP_DISABLED)
+		return WP_ENABLED;
+	return wp;
+}
+
+/*
  * Executes a command on current host and returns stripped command output.
  * If the command has failed (exit code is not zero), returns an empty string.
  * The caller is responsible for releasing the returned string.
diff --git a/futility/updater_utils.h b/futility/updater_utils.h
index a0dfc912..a5d012b8 100644
--- a/futility/updater_utils.h
+++ b/futility/updater_utils.h
@@ -176,6 +176,11 @@ void strip_string(char *s, const char *pattern);
 int save_file_from_stdin(const char *output);
 
 /*
+ * Returns true if the write protection is enabled on current system.
+ */
+int is_write_protection_enabled(struct updater_config *cfg);
+
+/*
  * Executes a command on current host and returns stripped command output.
  * If the command has failed (exit code is not zero), returns an empty string.
  * The caller is responsible for releasing the returned string.