https://github.com/torvalds/linux
Tip revision: 457391b0380335d5e9a5babdec90ac53928b23b4 authored by Linus Torvalds on 23 April 2023, 19:02:52 UTC
Linux 6.3
Linux 6.3
Tip revision: 457391b
mtdoops.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* MTD Oops/Panic logger
*
* Copyright © 2007 Nokia Corporation. All rights reserved.
*
* Author: Richard Purdie <rpurdie@openedhand.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/console.h>
#include <linux/vmalloc.h>
#include <linux/workqueue.h>
#include <linux/sched.h>
#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)
static unsigned long record_size = 4096;
module_param(record_size, ulong, 0400);
MODULE_PARM_DESC(record_size,
"record size for MTD OOPS pages in bytes (default 4096)");
static char mtddev[80];
module_param_string(mtddev, mtddev, 80, 0400);
MODULE_PARM_DESC(mtddev,
"name or index number of the MTD device to use");
static int dump_oops = 1;
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_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 {
struct kmsg_dumper dump;
int mtd_index;
struct work_struct work_erase;
struct work_struct work_write;
struct mtd_info *mtd;
int oops_pages;
int nextpage;
int nextcount;
unsigned long *oops_page_used;
unsigned long oops_buf_busy;
void *oops_buf;
} oops_cxt;
static void mark_page_used(struct mtdoops_context *cxt, int page)
{
set_bit(page, cxt->oops_page_used);
}
static void mark_page_unused(struct mtdoops_context *cxt, int page)
{
clear_bit(page, cxt->oops_page_used);
}
static int page_is_used(struct mtdoops_context *cxt, int page)
{
return test_bit(page, cxt->oops_page_used);
}
static int mtdoops_erase_block(struct mtdoops_context *cxt, int offset)
{
struct mtd_info *mtd = cxt->mtd;
u32 start_page_offset = mtd_div_by_eb(offset, mtd) * mtd->erasesize;
u32 start_page = start_page_offset / record_size;
u32 erase_pages = mtd->erasesize / record_size;
struct erase_info erase;
int ret;
int page;
erase.addr = offset;
erase.len = mtd->erasesize;
ret = mtd_erase(mtd, &erase);
if (ret) {
pr_warn("erase of region [0x%llx, 0x%llx] on \"%s\" failed\n",
(unsigned long long)erase.addr,
(unsigned long long)erase.len, mtddev);
return ret;
}
/* Mark pages as unused */
for (page = start_page; page < start_page + erase_pages; page++)
mark_page_unused(cxt, page);
return 0;
}
static void mtdoops_erase(struct mtdoops_context *cxt)
{
struct mtd_info *mtd = cxt->mtd;
int i = 0, j, ret, mod;
/* We were unregistered */
if (!mtd)
return;
mod = (cxt->nextpage * record_size) % mtd->erasesize;
if (mod != 0) {
cxt->nextpage = cxt->nextpage + ((mtd->erasesize - mod) / record_size);
if (cxt->nextpage >= cxt->oops_pages)
cxt->nextpage = 0;
}
while ((ret = mtd_block_isbad(mtd, cxt->nextpage * record_size)) > 0) {
badblock:
pr_warn("bad block at %08lx\n",
cxt->nextpage * record_size);
i++;
cxt->nextpage = cxt->nextpage + (mtd->erasesize / record_size);
if (cxt->nextpage >= cxt->oops_pages)
cxt->nextpage = 0;
if (i == cxt->oops_pages / (mtd->erasesize / record_size)) {
pr_err("all blocks bad!\n");
return;
}
}
if (ret < 0) {
pr_err("mtd_block_isbad failed, aborting\n");
return;
}
for (j = 0, ret = -1; (j < 3) && (ret < 0); j++)
ret = mtdoops_erase_block(cxt, cxt->nextpage * record_size);
if (ret >= 0) {
pr_debug("ready %d, %d\n",
cxt->nextpage, cxt->nextcount);
return;
}
if (ret == -EIO) {
ret = mtd_block_markbad(mtd, cxt->nextpage * record_size);
if (ret < 0 && ret != -EOPNOTSUPP) {
pr_err("block_markbad failed, aborting\n");
return;
}
}
goto badblock;
}
/* Scheduled work - when we can't proceed without erasing a block */
static void mtdoops_workfunc_erase(struct work_struct *work)
{
struct mtdoops_context *cxt =
container_of(work, struct mtdoops_context, work_erase);
mtdoops_erase(cxt);
}
static void mtdoops_inc_counter(struct mtdoops_context *cxt, int panic)
{
cxt->nextpage++;
if (cxt->nextpage >= cxt->oops_pages)
cxt->nextpage = 0;
cxt->nextcount++;
if (cxt->nextcount == 0xffffffff)
cxt->nextcount = 0;
if (page_is_used(cxt, cxt->nextpage)) {
pr_debug("not ready %d, %d (erase %s)\n",
cxt->nextpage, cxt->nextcount,
panic ? "immediately" : "scheduled");
if (panic) {
/* In case of panic, erase immediately */
mtdoops_erase(cxt);
} else {
/* Otherwise, schedule work to erase it "nicely" */
schedule_work(&cxt->work_erase);
}
} else {
pr_debug("ready %d, %d (no erase)\n",
cxt->nextpage, cxt->nextcount);
}
}
static void mtdoops_write(struct mtdoops_context *cxt, int panic)
{
struct mtd_info *mtd = cxt->mtd;
size_t retlen;
struct mtdoops_hdr *hdr;
int ret;
if (test_and_set_bit(0, &cxt->oops_buf_busy))
return;
/* Add mtdoops header to the buffer */
hdr = (struct mtdoops_hdr *)cxt->oops_buf;
hdr->seq = cxt->nextcount;
hdr->magic = MTDOOPS_KERNMSG_MAGIC_v2;
hdr->timestamp = ktime_get_real();
if (panic) {
ret = mtd_panic_write(mtd, cxt->nextpage * record_size,
record_size, &retlen, cxt->oops_buf);
if (ret == -EOPNOTSUPP) {
pr_err("Cannot write from panic without panic_write\n");
goto out;
}
} else
ret = mtd_write(mtd, cxt->nextpage * record_size,
record_size, &retlen, cxt->oops_buf);
if (retlen != record_size || ret < 0)
pr_err("write failure at %ld (%td of %ld written), error %d\n",
cxt->nextpage * record_size, retlen, record_size, ret);
mark_page_used(cxt, cxt->nextpage);
memset(cxt->oops_buf, 0xff, record_size);
mtdoops_inc_counter(cxt, panic);
out:
clear_bit(0, &cxt->oops_buf_busy);
}
static void mtdoops_workfunc_write(struct work_struct *work)
{
struct mtdoops_context *cxt =
container_of(work, struct mtdoops_context, work_write);
mtdoops_write(cxt, 0);
}
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 maxcount = 0xffffffff;
size_t retlen;
for (page = 0; page < cxt->oops_pages; page++) {
if (mtd_block_isbad(mtd, page * record_size))
continue;
/* Assume the page is used */
mark_page_used(cxt, page);
ret = mtd_read(mtd, page * record_size, sizeof(hdr),
&retlen, (u_char *)&hdr);
if (retlen != sizeof(hdr) ||
(ret < 0 && !mtd_is_bitflip(ret))) {
pr_err("read failure at %ld (%zu of %zu read), err %d\n",
page * record_size, retlen, sizeof(hdr), ret);
continue;
}
if (hdr.seq == 0xffffffff && hdr.magic == 0xffffffff)
mark_page_unused(cxt, page);
if (hdr.seq == 0xffffffff ||
(hdr.magic != MTDOOPS_KERNMSG_MAGIC_v1 &&
hdr.magic != MTDOOPS_KERNMSG_MAGIC_v2))
continue;
if (maxcount == 0xffffffff) {
maxcount = hdr.seq;
maxpos = page;
} else if (hdr.seq < 0x40000000 && maxcount > 0xc0000000) {
maxcount = hdr.seq;
maxpos = page;
} else if (hdr.seq > maxcount && hdr.seq < 0xc0000000) {
maxcount = hdr.seq;
maxpos = page;
} else if (hdr.seq > maxcount && hdr.seq > 0xc0000000
&& maxcount > 0x80000000) {
maxcount = hdr.seq;
maxpos = page;
}
}
if (maxcount == 0xffffffff) {
cxt->nextpage = cxt->oops_pages - 1;
cxt->nextcount = 0;
}
else {
cxt->nextpage = maxpos;
cxt->nextcount = maxcount;
}
mtdoops_inc_counter(cxt, 0);
}
static void mtdoops_do_dump(struct kmsg_dumper *dumper,
enum kmsg_dump_reason reason)
{
struct mtdoops_context *cxt = container_of(dumper,
struct mtdoops_context, dump);
struct kmsg_dump_iter iter;
/* Only dump oopses if dump_oops is set */
if (reason == KMSG_DUMP_OOPS && !dump_oops)
return;
kmsg_dump_rewind(&iter);
if (test_and_set_bit(0, &cxt->oops_buf_busy))
return;
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) {
/* Panics must be written immediately */
mtdoops_write(cxt, 1);
} else {
/* For other cases, schedule work to write it "nicely" */
schedule_work(&cxt->work_write);
}
}
static void mtdoops_notify_add(struct mtd_info *mtd)
{
struct mtdoops_context *cxt = &oops_cxt;
u64 mtdoops_pages = div_u64(mtd->size, record_size);
int err;
if (!strcmp(mtd->name, mtddev))
cxt->mtd_index = mtd->index;
if (mtd->index != cxt->mtd_index || cxt->mtd_index < 0)
return;
if (mtd->size < mtd->erasesize * 2) {
pr_err("MTD partition %d not big enough for mtdoops\n",
mtd->index);
return;
}
if (mtd->erasesize < record_size) {
pr_err("eraseblock size of MTD partition %d too small\n",
mtd->index);
return;
}
if (mtd->size > MTDOOPS_MAX_MTD_SIZE) {
pr_err("mtd%d is too large (limit is %d MiB)\n",
mtd->index, MTDOOPS_MAX_MTD_SIZE / 1024 / 1024);
return;
}
/* oops_page_used is a bit field */
cxt->oops_page_used =
vmalloc(array_size(sizeof(unsigned long),
DIV_ROUND_UP(mtdoops_pages,
BITS_PER_LONG)));
if (!cxt->oops_page_used) {
pr_err("could not allocate page array\n");
return;
}
cxt->dump.max_reason = KMSG_DUMP_OOPS;
cxt->dump.dump = mtdoops_do_dump;
err = kmsg_dump_register(&cxt->dump);
if (err) {
pr_err("registering kmsg dumper failed, error %d\n", err);
vfree(cxt->oops_page_used);
cxt->oops_page_used = NULL;
return;
}
cxt->mtd = mtd;
cxt->oops_pages = (int)mtd->size / record_size;
find_next_position(cxt);
pr_info("Attached to MTD device %d\n", mtd->index);
}
static void mtdoops_notify_remove(struct mtd_info *mtd)
{
struct mtdoops_context *cxt = &oops_cxt;
if (mtd->index != cxt->mtd_index || cxt->mtd_index < 0)
return;
if (kmsg_dump_unregister(&cxt->dump) < 0)
pr_warn("could not unregister kmsg_dumper\n");
cxt->mtd = NULL;
flush_work(&cxt->work_erase);
flush_work(&cxt->work_write);
}
static struct mtd_notifier mtdoops_notifier = {
.add = mtdoops_notify_add,
.remove = mtdoops_notify_remove,
};
static int __init mtdoops_init(void)
{
struct mtdoops_context *cxt = &oops_cxt;
int mtd_index;
char *endp;
if (strlen(mtddev) == 0) {
pr_err("mtd device (mtddev=name/number) must be supplied\n");
return -EINVAL;
}
if ((record_size & 4095) != 0) {
pr_err("record_size must be a multiple of 4096\n");
return -EINVAL;
}
if (record_size < 4096) {
pr_err("record_size must be over 4096 bytes\n");
return -EINVAL;
}
/* Setup the MTD device to use */
cxt->mtd_index = -1;
mtd_index = simple_strtoul(mtddev, &endp, 0);
if (*endp == '\0')
cxt->mtd_index = mtd_index;
cxt->oops_buf = vmalloc(record_size);
if (!cxt->oops_buf)
return -ENOMEM;
memset(cxt->oops_buf, 0xff, record_size);
cxt->oops_buf_busy = 0;
INIT_WORK(&cxt->work_erase, mtdoops_workfunc_erase);
INIT_WORK(&cxt->work_write, mtdoops_workfunc_write);
register_mtd_user(&mtdoops_notifier);
return 0;
}
static void __exit mtdoops_exit(void)
{
struct mtdoops_context *cxt = &oops_cxt;
unregister_mtd_user(&mtdoops_notifier);
vfree(cxt->oops_buf);
vfree(cxt->oops_page_used);
}
module_init(mtdoops_init);
module_exit(mtdoops_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Richard Purdie <rpurdie@openedhand.com>");
MODULE_DESCRIPTION("MTD Oops/Panic console logger/driver");