s390/boot: Add timestamps to early boot messages

When CONFIG_PRINTK_TIME is enabled, add timestamps to boot messages in
the same format as regular printk. Timestamps appear only with earlyprintk
and are stored in the boot messages ring buffer, but are not propagated
to main kernel messages (if earlyprintk is not enabled). This prevents
double timestamps in the output.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

arch/s390/boot/printk.c

@@ -190,12 +190,29 @@ static void boot_console_earlyprintk(const char *buf)
 		return;
 	buf = printk_skip_level(buf);
 	/* print debug messages only when bootdebug is enabled */
-	if (level == LOGLEVEL_DEBUG && (!bootdebug || !bootdebug_filter_match(buf)))
+	if (level == LOGLEVEL_DEBUG && (!bootdebug || !bootdebug_filter_match(skip_timestamp(buf))))
 		return;
 	if (boot_ignore_loglevel || level < boot_console_loglevel)
 		sclp_early_printk(buf);
 }
 
+static char *add_timestamp(char *buf)
+{
+#ifdef CONFIG_PRINTK_TIME
+	union tod_clock *boot_clock = (union tod_clock *)&get_lowcore()->boot_clock;
+	unsigned long ns = tod_to_ns(get_tod_clock() - boot_clock->tod);
+	char ts[MAX_NUMLEN];
+
+	*buf++ = '[';
+	buf += strpad(buf, MAX_NUMLEN, as_dec(ts, ns / NSEC_PER_SEC, 0), 5, 0, 0);
+	*buf++ = '.';
+	buf += strpad(buf, MAX_NUMLEN, as_dec(ts, (ns % NSEC_PER_SEC) / NSEC_PER_USEC, 0), 6, 1, 0);
+	*buf++ = ']';
+	*buf++ = ' ';
+#endif
+	return buf;
+}
+
 #define va_arg_len_type(args, lenmod, typemod)				\
 	((lenmod == 'l') ? va_arg(args, typemod long) :			\
 	 (lenmod == 'h') ? (typemod short)va_arg(args, typemod int) :	\
@@ -215,10 +232,10 @@ int boot_printk(const char *fmt, ...)
 	ssize_t len;
 	int pad;
 
-	if (!printk_get_level(fmt)) {
-		*p++ = KERN_SOH_ASCII;
-		*p++ = '0' + MESSAGE_LOGLEVEL_DEFAULT;
-	}
+	*p++ = KERN_SOH_ASCII;
+	*p++ = printk_get_level(fmt) ?: '0' + MESSAGE_LOGLEVEL_DEFAULT;
+	p = add_timestamp(p);
+	fmt = printk_skip_level(fmt);
 
 	va_start(args, fmt);
 	for (; p < end && *fmt; fmt++) {

arch/s390/include/asm/boot_data.h

@@ -55,4 +55,15 @@ static inline bool bootdebug_filter_match(const char *buf)
 	return false;
 }
 
+static inline const char *skip_timestamp(const char *buf)
+{
+#ifdef CONFIG_PRINTK_TIME
+	const char *p = memchr(buf, ']', strlen(buf));
+
+	if (p && p[1] == ' ')
+		return p + 2;
+#endif
+	return buf;
+}
+
 #endif /* _ASM_S390_BOOT_DATA_H */

arch/s390/kernel/setup.c

@@ -892,7 +892,7 @@ static void __init print_rb_entry(const char *buf)
 	char fmt[] = KERN_SOH "0boot: %s";
 	int level = printk_get_level(buf);
 
-	buf = printk_skip_level(buf);
+	buf = skip_timestamp(printk_skip_level(buf));
 	if (level == KERN_DEBUG[1] && (!bootdebug || !bootdebug_filter_match(buf)))
 		return;