Messages in this thread Patch in this message | | | Date | Tue, 29 Mar 2022 15:53:28 -0700 | Subject | [PATCH] Create a proper header for the saved mtdoops. | From | Jean-Marc Eurin <> |
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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@google.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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