Change in coreboot[master]: elogtool: add "clear" command

[Ricardo Quesada (Code Review)]

Ricardo Quesada has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/56866 )

Change subject: elogtool: add "clear" command
......................................................................

elogtool: add "clear" command

Adds "clear" command to cbfsutil/elogtool tool.
"clear" clears the RW_ELOG using flashrom with ELOG_TYPE_EOL.
And inserts a ELOG_TYPE_LOG_CLEAR event.

Usage:
$ elogtool clear

BUG=b:172210863

Change-Id: I7ea64ea748ee4c3647b0256be51203464a54c2dd
Signed-off-by: Ricardo Quesada 
---
M src/commonlib/bsd/elog.c
M src/commonlib/bsd/include/commonlib/bsd/elog.h
M util/cbfstool/elogtool.c
M util/cbfstool/eventlog.c
M util/cbfstool/eventlog.h
5 files changed, 160 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/66/56866/1

diff --git a/src/commonlib/bsd/elog.c b/src/commonlib/bsd/elog.c
index 6c927aa..a538dd3 100644
--- a/src/commonlib/bsd/elog.c
+++ b/src/commonlib/bsd/elog.c
@@ -44,3 +44,56 @@
    // right after the header.
    return (const void *)(&event[1]);
 }
+
+static inline uint8_t mybin2bcd(uint8_t val)
+{
+	return ((val / 10) << 4) | (val % 10);
+}
+
+/*
+ * Populate timestamp in event header with given time.
+ */
+void elog_fill_timestamp(struct event_header *event, uint8_t sec, uint8_t min,
+	uint8_t hour, uint8_t mday, uint8_t mon, uint8_t year)
+{
+	event->second = mybin2bcd(sec);
+	event->minute = mybin2bcd(min);
+	event->hour = mybin2bcd(hour);
+	event->day = mybin2bcd(mday);
+	event->month = mybin2bcd(mon);
+	event->year = mybin2bcd(year % 100);
+
+	/* Basic sanity check of expected ranges */
+	if (event->month > 0x12 || event->day > 0x31 || event->hour > 0x23 ||
+	    event->minute > 0x59 || event->second > 0x59)
+	{
+		event->year   = 0;
+		event->month  = 0;
+		event->day    = 0;
+		event->hour   = 0;
+		event->minute = 0;
+		event->second = 0;
+	}
+}
+
+/*
+ * Update the checksum at the last byte
+ */
+void elog_update_checksum(struct event_header *event, uint8_t checksum)
+{
+	uint8_t *event_data = (uint8_t *)event;
+	event_data[event->length - 1] = checksum;
+}
+
+/*
+ * Simple byte checksum for events
+ */
+uint8_t elog_checksum_event(struct event_header *event)
+{
+	uint8_t index, checksum = 0;
+	uint8_t *data = (uint8_t *)event;
+
+	for (index = 0; index < event->length; index++)
+		checksum += data[index];
+	return checksum;
+}
\ No newline at end of file
diff --git a/src/commonlib/bsd/include/commonlib/bsd/elog.h b/src/commonlib/bsd/include/commonlib/bsd/elog.h
index 0d41157..54e7ec4 100644
--- a/src/commonlib/bsd/include/commonlib/bsd/elog.h
+++ b/src/commonlib/bsd/include/commonlib/bsd/elog.h
@@ -313,5 +313,9 @@
 enum cb_err elog_verify_header(const struct elog_header *header);
 const struct event_header *elog_get_next_event(const struct event_header *event);
 const void *event_get_data(const struct event_header *event);
+void elog_fill_timestamp(struct event_header *event, uint8_t sec, uint8_t min,
+	uint8_t hour, uint8_t mday, uint8_t mon, uint8_t year);
+void elog_update_checksum(struct event_header *event, uint8_t checksum);
+uint8_t elog_checksum_event(struct event_header *event);

#endif  /* _COMMONLIB_BSD_ELOG_H_ */
diff --git a/util/cbfstool/elogtool.c b/util/cbfstool/elogtool.c
index ba59eac..4b05f6c 100644
--- a/util/cbfstool/elogtool.c
+++ b/util/cbfstool/elogtool.c
@@ -33,7 +33,9 @@
    		"USAGE:\n"
    		"\t%s COMMAND [-f <filename>]\n\n"
    		"where, COMMAND is:\n"
-			"  list = lists all the event logs in human readable format\n\n"
+			"  list = lists all the event logs in human readable format\n"
+			"  clear = clears the contents RW_ELOG region from flash\n"
+			"\n"
    		"ARGS\n"
    		"-f, --file <filename>   Input file that holds event log partition.\n"
    		"                        If empty it will try to read from the RW_ELOG ROM region\n"
@@ -111,6 +113,76 @@
    return ret;
 }

+/*
+ * Clears the elog events from buf, which is a valid RW_ELOG region.
+ * A LOG_CLEAR event is appended
+ */
+static int elog_clear_events(struct buffer* buf)
+{
+	const struct event_header *event;
+	uint32_t used_data_size = 0;
+	void* data_offset;
+	size_t data_size;
+
+	data_size = buf->size - sizeof(struct elog_header);
+	data_offset = buf->data + sizeof(struct elog_header);
+
+	/* Must have at least size for event + data + checksum */
+	if (data_size < sizeof(struct event_header) + sizeof(used_data_size) + 1)
+		return ELOGTOOL_EXIT_INVALID_ELOG_FORMAT;
+
+	/*
+	 * We calcualte the size of the "used" buffer, needed for ELOG_TYPE_LOG_CLEAR.
+	 * Then we overwritte the entire buffer with ELOG_TYPE_EOL.
+	 * Finally we insert a LOG_CLEAR event into the buffer.
+	 */
+	event = (const struct event_header *)(data_offset);
+
+	while ((const char*)(event) < buf->data + buf->size) {
+		if (event->type == ELOG_TYPE_EOL || event->length == 0)
+			break;
+
+		used_data_size += event->length;
+		event = elog_get_next_event(event);
+	}
+
+	memset(data_offset, ELOG_TYPE_EOL, data_size);
+
+	eventlog_init_event(data_offset, ELOG_TYPE_LOG_CLEAR,
+		&used_data_size, sizeof(used_data_size));
+
+	return ELOGTOOL_EXIT_SUCCESS;
+}
+
+static int cmd_clear(void)
+{
+	int ret;
+
+	/* Returned buffer must be freed. */
+	struct buffer buf;
+	ret = elog_read(NULL, &buf);
+	if (ret != 0)
+		return ret;
+
+	ret = elog_clear_events(&buf);
+	if (ret != 0) {
+		buffer_delete(&buf);
+		return ret;
+	}
+
+	if (flashrom_write(FLASHROM_PROGRAMMER_INTERNAL_AP, "RW_ELOG",
+			(void *)buf.data, buf.size) != VB2_SUCCESS) {
+
+		fprintf(stderr,
+			"Failed to write to RW_ELOG region using flashrom\n");
+		ret = ELOGTOOL_EXIT_BAD_INPUT_PATH;
+
+		/* Fallthrough */
+	}
+
+	buffer_delete(&buf);
+	return ret;
+}

int main(int argc, char **argv)
 {
@@ -157,5 +229,8 @@
    if (!strcmp(argv[optind], "list"))
    	return cmd_list(input_file);

+	if (!strcmp(argv[optind], "clear"))
+		return cmd_clear();
+
    return ELOGTOOL_EXIT_SUCCESS;
 }
diff --git a/util/cbfstool/eventlog.c b/util/cbfstool/eventlog.c
index 2d99f92..ccec32b 100644
--- a/util/cbfstool/eventlog.c
+++ b/util/cbfstool/eventlog.c
@@ -634,3 +634,27 @@
    eventlog_printf_ignore_separator_once = 1;
    eventlog_printf("\n");
 }
+
+void eventlog_init_event(struct event_header* event, uint8_t type, const void* data, int data_size)
+{
+	time_t secs = time(NULL);
+	struct tm tm;
+
+	event->type = type;
+	gmtime_r(&secs, &tm);
+	elog_fill_timestamp(event, tm.tm_sec, tm.tm_min, tm.tm_hour, tm.tm_mday, tm.tm_mon, tm.tm_year);
+
+	if (data && data) {
+		void* ptr = (uint32_t*) &event[1];
+		memcpy(ptr, data, data_size);
+	}
+
+	/* Header + data + checksum */
+	event->length = sizeof(*event) + data_size + 1;
+
+	/* Zero the checksum byte and then compute checksum */
+	elog_update_checksum(event, 0);
+	elog_update_checksum(event, -(elog_checksum_event(event)));
+
+
+}
diff --git a/util/cbfstool/eventlog.h b/util/cbfstool/eventlog.h
index baecb21..e968e83 100644
--- a/util/cbfstool/eventlog.h
+++ b/util/cbfstool/eventlog.h
@@ -3,8 +3,11 @@
 #ifndef EVENTLOG_H_
 #define EVENTLOG_H_

+#include <stdint.h>
+
 struct event_header;

void eventlog_print_event(const struct event_header *event, int count);
+void eventlog_init_event(struct event_header* event, uint8_t type, const void* data, int data_size);

#endif // EVENTLOG_H_