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Message-Id: <20220329225328.396209-1-jmeurin@google.com>
Date: Tue, 29 Mar 2022 15:53:28 -0700
From: Jean-Marc Eurin <jmeurin@...gle.com>
To: Miquel Raynal <miquel.raynal@...tlin.com>,
Richard Weinberger <richard@....at>,
Vignesh Raghavendra <vigneshr@...com>
Cc: linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
Jean-Marc Eurin <jmeurin@...gle.com>
Subject: [PATCH] Create a proper header for the saved mtdoops.
Avoid a panic if the header size changes.
Add a timestamp to the oops header.
Tested:
Triggered panic saved correctly:
xxd -l 0x20 -s 0x0000 /dev/mtdblock1
00000000: 0100 0000 005e 005d 935d 4117 c5bf df16 .....^.].]A.....
00000010: 3c36 3e5b 2020 3133 392e 3938 3039 3533 <6>[ 139.980953
Signed-off-by: Jean-Marc Eurin <jmeurin@...gle.com>
---
drivers/mtd/mtdoops.c | 57 +++++++++++++++++++++++++------------------
1 file changed, 33 insertions(+), 24 deletions(-)
diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index 227df24387df..6a51baa172ae 100644
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -16,15 +16,13 @@
#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>
/* Maximum MTD partition size */
#define MTDOOPS_MAX_MTD_SIZE (8 * 1024 * 1024)
-#define MTDOOPS_KERNMSG_MAGIC 0x5d005d00
-#define MTDOOPS_HEADER_SIZE 8
-
static unsigned long record_size = 4096;
module_param(record_size, ulong, 0400);
MODULE_PARM_DESC(record_size,
@@ -40,6 +38,14 @@ 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 0x5d005e00
+
+struct mtdoops_hdr {
+ u32 seq;
+ u32 magic;
+ ktime_t timestamp;
+} __packed;
+
static struct mtdoops_context {
struct kmsg_dumper dump;
@@ -178,16 +184,18 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
{
struct mtd_info *mtd = cxt->mtd;
size_t retlen;
- u32 *hdr;
+ struct mtdoops_hdr *hdr;
int ret;
+ ktime_t ktime = ktime_get_real();
if (test_and_set_bit(0, &cxt->oops_buf_busy))
return;
/* Add mtdoops header to the buffer */
- hdr = cxt->oops_buf;
- hdr[0] = cxt->nextcount;
- hdr[1] = MTDOOPS_KERNMSG_MAGIC;
+ hdr = (struct mtdoops_hdr *)cxt->oops_buf;
+ hdr->seq = cxt->nextcount;
+ hdr->magic = MTDOOPS_KERNMSG_MAGIC;
+ hdr->timestamp = ktime_get_real();
if (panic) {
ret = mtd_panic_write(mtd, cxt->nextpage * record_size,
@@ -222,8 +230,9 @@ static void mtdoops_workfunc_write(struct work_struct *work)
static void find_next_position(struct mtdoops_context *cxt)
{
struct mtd_info *mtd = cxt->mtd;
+ struct mtdoops_hdr hdr;
int ret, page, maxpos = 0;
- u32 count[2], maxcount = 0xffffffff;
+ u32 maxcount = 0xffffffff;
size_t retlen;
for (page = 0; page < cxt->oops_pages; page++) {
@@ -231,32 +240,31 @@ static void find_next_position(struct mtdoops_context *cxt)
continue;
/* Assume the page is used */
mark_page_used(cxt, page);
- ret = mtd_read(mtd, page * record_size, MTDOOPS_HEADER_SIZE,
- &retlen, (u_char *)&count[0]);
- if (retlen != MTDOOPS_HEADER_SIZE ||
+ ret = mtd_read(mtd, page * record_size, sizeof(hdr),
+ &retlen, (u_char *)&hdr);
+ if (retlen != sizeof(hdr) ||
(ret < 0 && !mtd_is_bitflip(ret))) {
printk(KERN_ERR "mtdoops: read failure at %ld (%td of %d read), err %d\n",
- page * record_size, retlen,
- MTDOOPS_HEADER_SIZE, ret);
+ page * record_size, retlen, sizeof(hdr), ret);
continue;
}
- if (count[0] == 0xffffffff && count[1] == 0xffffffff)
+ if (hdr.seq == 0xffffffff && hdr.magic == 0xffffffff)
mark_page_unused(cxt, page);
- if (count[0] == 0xffffffff || count[1] != MTDOOPS_KERNMSG_MAGIC)
+ if (hdr.seq == 0xffffffff || hdr.magic != MTDOOPS_KERNMSG_MAGIC)
continue;
if (maxcount == 0xffffffff) {
- maxcount = count[0];
+ maxcount = hdr.seq;
maxpos = page;
- } else if (count[0] < 0x40000000 && maxcount > 0xc0000000) {
- maxcount = count[0];
+ } else if (hdr.seq < 0x40000000 && maxcount > 0xc0000000) {
+ maxcount = hdr.seq;
maxpos = page;
- } else if (count[0] > maxcount && count[0] < 0xc0000000) {
- maxcount = count[0];
+ } else if (hdr.seq > maxcount && hdr.seq < 0xc0000000) {
+ maxcount = hdr.seq;
maxpos = page;
- } else if (count[0] > maxcount && count[0] > 0xc0000000
+ } else if (hdr.seq > maxcount && hdr.seq > 0xc0000000
&& maxcount > 0x80000000) {
- maxcount = count[0];
+ maxcount = hdr.seq;
maxpos = page;
}
}
@@ -287,8 +295,9 @@ static void mtdoops_do_dump(struct kmsg_dumper *dumper,
if (test_and_set_bit(0, &cxt->oops_buf_busy))
return;
- kmsg_dump_get_buffer(&iter, true, cxt->oops_buf + MTDOOPS_HEADER_SIZE,
- record_size - MTDOOPS_HEADER_SIZE, NULL);
+ kmsg_dump_get_buffer(&iter, true,
+ cxt->oops_buf + sizeof(struct mtdoops_hdr),
+ record_size - sizeof(struct mtdoops_hdr), NULL);
clear_bit(0, &cxt->oops_buf_busy);
if (reason != KMSG_DUMP_OOPS) {
--
2.35.1.1021.g381101b075-goog
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