mtd: mtdoops: Add a timestamp to the mtdoops header.

On some systems, the oops only has relative time from boot.

Signed-off-by: Jean-Marc Eurin <jmeurin@google.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220425160927.3823016-1-jmeurin@google.com

diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index 186eeb0..3d4a2ff 100644 (file)
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -16,6 +16,7 @@
 #include <linux/wait.h>
 #include <linux/delay.h>
 #include <linux/interrupt.h>
+#include <linux/timekeeping.h>
 #include <linux/mtd/mtd.h>
 #include <linux/kmsg_dump.h>
 
@@ -37,11 +38,13 @@ module_param(dump_oops, int, 0600);
 MODULE_PARM_DESC(dump_oops,
                "set to 1 to dump oopses, 0 to only dump panics (default 1)");
 
-#define MTDOOPS_KERNMSG_MAGIC 0x5d005d00
+#define MTDOOPS_KERNMSG_MAGIC_v1 0x5d005d00  /* Original */
+#define MTDOOPS_KERNMSG_MAGIC_v2 0x5d005e00  /* Adds the timestamp */
 
 struct mtdoops_hdr {
        u32 seq;
        u32 magic;
+       ktime_t timestamp;
 } __packed;
 
 static struct mtdoops_context {
@@ -191,7 +194,8 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
        /* Add mtdoops header to the buffer */
        hdr = (struct mtdoops_hdr *)cxt->oops_buf;
        hdr->seq = cxt->nextcount;
-       hdr->magic = MTDOOPS_KERNMSG_MAGIC;
+       hdr->magic = MTDOOPS_KERNMSG_MAGIC_v2;
+       hdr->timestamp = ktime_get_real();
 
        if (panic) {
                ret = mtd_panic_write(mtd, cxt->nextpage * record_size,
@@ -247,7 +251,9 @@ static void find_next_position(struct mtdoops_context *cxt)
 
                if (hdr.seq == 0xffffffff && hdr.magic == 0xffffffff)
                        mark_page_unused(cxt, page);
-               if (hdr.seq == 0xffffffff || hdr.magic != MTDOOPS_KERNMSG_MAGIC)
+               if (hdr.seq == 0xffffffff ||
+                   (hdr.magic != MTDOOPS_KERNMSG_MAGIC_v1 &&
+                    hdr.magic != MTDOOPS_KERNMSG_MAGIC_v2))
                        continue;
                if (maxcount == 0xffffffff) {
                        maxcount = hdr.seq;