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Commit 3f738cb7 authored by Patrick Daly's avatar Patrick Daly Committed by Matt Wagantall
Browse files

printk: Add LOG_BUF_MAGIC 



Enable post-mortem ramdump analysis to retrieve the valid portions of the
log buffer in the event that portions are corrupted.

Change-Id: Icc47bdb5c030d8548509d14c8016892cc393dafa
Signed-off-by: default avatarPatrick Daly <pdaly@codeaurora.org>
[abhimany: resolve trivial merge conflicts]
Signed-off-by: default avatarAbhimanyu Kapur <abhimany@codeaurora.org>
parent 6672b849

kernel/printk/printk.c

+11 −0
Original line number Diff line number Diff line
@@ -227,6 +227,9 @@ struct printk_log { 
	u8 facility;		/* syslog facility */

	u8 flags:5;		/* internal record flags */

	u8 level:3;		/* syslog level */

#if defined(CONFIG_LOG_BUF_MAGIC)

	u32 magic;		/* handle for ramdump analysis tools */

#endif

};



/*
@@ -286,6 +289,12 @@ u32 log_buf_len_get(void) 
{

	return log_buf_len;

}

#if defined(CONFIG_LOG_BUF_MAGIC)

static u32 __log_align __used = LOG_ALIGN;

#define LOG_MAGIC(msg) ((msg)->magic = 0x5d7aefca)

#else

#define LOG_MAGIC(msg)

#endif



/* human readable text of the record */

static char *log_text(const struct printk_log *msg)
@@ -440,6 +449,7 @@ static int log_store(int facility, int level, 
		 * to signify a wrap around.

		 */

		memset(log_buf + log_next_idx, 0, sizeof(struct printk_log));

		LOG_MAGIC((struct printk_log *)(log_buf + log_next_idx));

		log_next_idx = 0;

	}
@@ -456,6 +466,7 @@ static int log_store(int facility, int level, 
	msg->facility = facility;

	msg->level = level & 7;

	msg->flags = flags & 0x1f;

	LOG_MAGIC(msg);

	if (ts_nsec > 0)

		msg->ts_nsec = ts_nsec;

	else

lib/Kconfig.debug

+9 −0
Original line number Diff line number Diff line
@@ -26,6 +26,15 @@ config MESSAGE_LOGLEVEL_DEFAULT 
	  that are auditing their logs closely may want to set it to a lower

	  priority.



config LOG_BUF_MAGIC

	bool "Recovery of partially corrupted dmesg from ramdumps"

	depends on PRINTK

	help

	  Select this option to add a magic number to the log buf record. In the

	  event that a log buf record is corrupted, post-mortem crash analysis

	  tools may use this magic number to search for the next noncorrupted

	  log record.



config BOOT_PRINTK_DELAY

	bool "Delay each boot printk message by N milliseconds"

	depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY