[MTD] oops and panic message logging to MTD device

Kernel oops and panic messages are invaluable when debugging crashes.
These messages often don't make it to flash based logging methods (say a
syslog on jffs2) due to the overheads involved in writing to flash.

This patch allows you to turn an MTD partition into a circular log
buffer where kernel oops and panic messages are written to. The messages
are obtained by registering a console driver and checking
oops_in_progress. Erases are performed in advance to maximise the
chances of a saving messages.

To activate it, add console=ttyMTDx to the kernel commandline (where x
is the mtd device number to use).

Signed-off-by: Richard Purdie <rpurdie@openedhand.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
This commit is contained in:
Richard Purdie 2007-05-29 13:31:42 +01:00 committed by David Woodhouse
parent 1100b47ea5
commit 4b23aff083
3 changed files with 374 additions and 0 deletions

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@ -278,6 +278,14 @@ config SSFDC
This enables read only access to SmartMedia formatted NAND
flash. You can mount it with FAT file system.
config MTD_OOPS
tristate "Log panic/oops to an MTD buffer"
depends on MTD
help
This enables panic and oops messages to be logged to a circular
buffer in a flash partition where it can be read back at some
later point.
source "drivers/mtd/chips/Kconfig"
source "drivers/mtd/maps/Kconfig"

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@ -22,6 +22,7 @@ obj-$(CONFIG_NFTL) += nftl.o
obj-$(CONFIG_INFTL) += inftl.o
obj-$(CONFIG_RFD_FTL) += rfd_ftl.o
obj-$(CONFIG_SSFDC) += ssfdc.o
obj-$(CONFIG_MTD_OOPS) += mtdoops.o
nftl-objs := nftlcore.o nftlmount.o
inftl-objs := inftlcore.o inftlmount.o

365
drivers/mtd/mtdoops.c Normal file
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@ -0,0 +1,365 @@
/*
* MTD Oops/Panic logger
*
* Copyright (C) 2007 Nokia Corporation. All rights reserved.
*
* Author: Richard Purdie <rpurdie@openedhand.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
*/
#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/mtd/mtd.h>
#define OOPS_PAGE_SIZE 4096
static struct mtdoops_context {
int mtd_index;
struct work_struct work;
struct mtd_info *mtd;
int oops_pages;
int nextpage;
int nextcount;
void *oops_buf;
int ready;
int writecount;
} oops_cxt;
static void mtdoops_erase_callback(struct erase_info *done)
{
wait_queue_head_t *wait_q = (wait_queue_head_t *)done->priv;
wake_up(wait_q);
}
static int mtdoops_erase_block(struct mtd_info *mtd, int offset)
{
struct erase_info erase;
DECLARE_WAITQUEUE(wait, current);
wait_queue_head_t wait_q;
int ret;
init_waitqueue_head(&wait_q);
erase.mtd = mtd;
erase.callback = mtdoops_erase_callback;
erase.addr = offset;
if (mtd->erasesize < OOPS_PAGE_SIZE)
erase.len = OOPS_PAGE_SIZE;
else
erase.len = mtd->erasesize;
erase.priv = (u_long)&wait_q;
set_current_state(TASK_INTERRUPTIBLE);
add_wait_queue(&wait_q, &wait);
ret = mtd->erase(mtd, &erase);
if (ret) {
set_current_state(TASK_RUNNING);
remove_wait_queue(&wait_q, &wait);
printk (KERN_WARNING "mtdoops: erase of region [0x%x, 0x%x] "
"on \"%s\" failed\n",
erase.addr, erase.len, mtd->name);
return ret;
}
schedule(); /* Wait for erase to finish. */
remove_wait_queue(&wait_q, &wait);
return 0;
}
static int mtdoops_inc_counter(struct mtdoops_context *cxt)
{
struct mtd_info *mtd = cxt->mtd;
size_t retlen;
u32 count;
int ret;
cxt->nextpage++;
if (cxt->nextpage > cxt->oops_pages)
cxt->nextpage = 0;
cxt->nextcount++;
if (cxt->nextcount == 0xffffffff)
cxt->nextcount = 0;
ret = mtd->read(mtd, cxt->nextpage * OOPS_PAGE_SIZE, 4,
&retlen, (u_char *) &count);
if ((retlen != 4) || (ret < 0)) {
printk(KERN_ERR "mtdoops: Read failure at %d (%d of 4 read)"
", err %d.\n", cxt->nextpage * OOPS_PAGE_SIZE,
retlen, ret);
return 1;
}
/* See if we need to erase the next block */
if (count != 0xffffffff)
return 1;
printk(KERN_DEBUG "mtdoops: Ready %d, %d (no erase)\n",
cxt->nextpage, cxt->nextcount);
cxt->ready = 1;
return 0;
}
static void mtdoops_prepare(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 * OOPS_PAGE_SIZE) % mtd->erasesize;
if (mod != 0) {
cxt->nextpage = cxt->nextpage + ((mtd->erasesize - mod) / OOPS_PAGE_SIZE);
if (cxt->nextpage > cxt->oops_pages)
cxt->nextpage = 0;
}
while (mtd->block_isbad &&
mtd->block_isbad(mtd, cxt->nextpage * OOPS_PAGE_SIZE)) {
badblock:
printk(KERN_WARNING "mtdoops: Bad block at %08x\n",
cxt->nextpage * OOPS_PAGE_SIZE);
i++;
cxt->nextpage = cxt->nextpage + (mtd->erasesize / OOPS_PAGE_SIZE);
if (cxt->nextpage > cxt->oops_pages)
cxt->nextpage = 0;
if (i == (cxt->oops_pages / (mtd->erasesize / OOPS_PAGE_SIZE))) {
printk(KERN_ERR "mtdoops: All blocks bad!\n");
return;
}
}
for (j = 0, ret = -1; (j < 3) && (ret < 0); j++)
ret = mtdoops_erase_block(mtd, cxt->nextpage * OOPS_PAGE_SIZE);
if (ret < 0) {
if (mtd->block_markbad)
mtd->block_markbad(mtd, cxt->nextpage * OOPS_PAGE_SIZE);
goto badblock;
}
printk(KERN_DEBUG "mtdoops: Ready %d, %d \n", cxt->nextpage, cxt->nextcount);
cxt->ready = 1;
}
static void mtdoops_workfunc(struct work_struct *work)
{
struct mtdoops_context *cxt =
container_of(work, struct mtdoops_context, work);
mtdoops_prepare(cxt);
}
static int find_next_position(struct mtdoops_context *cxt)
{
struct mtd_info *mtd = cxt->mtd;
int page, maxpos = 0;
u32 count, maxcount = 0xffffffff;
size_t retlen;
for (page = 0; page < cxt->oops_pages; page++) {
mtd->read(mtd, page * OOPS_PAGE_SIZE, 4, &retlen, (u_char *) &count);
if (count == 0xffffffff)
continue;
if (maxcount == 0xffffffff) {
maxcount = count;
maxpos = page;
} else if ((count < 0x40000000) && (maxcount > 0xc0000000)) {
maxcount = count;
maxpos = page;
} else if ((count > maxcount) && (count < 0xc0000000)) {
maxcount = count;
maxpos = page;
} else if ((count > maxcount) && (count > 0xc0000000)
&& (maxcount > 0x80000000)) {
maxcount = count;
maxpos = page;
}
}
if (maxcount == 0xffffffff) {
cxt->nextpage = 0;
cxt->nextcount = 1;
cxt->ready = 1;
printk(KERN_DEBUG "mtdoops: Ready %d, %d (first init)\n",
cxt->nextpage, cxt->nextcount);
return 0;
}
cxt->nextpage = maxpos;
cxt->nextcount = maxcount;
return mtdoops_inc_counter(cxt);
}
static void mtdoops_notify_add(struct mtd_info *mtd)
{
struct mtdoops_context *cxt = &oops_cxt;
int ret;
if ((mtd->index != cxt->mtd_index) || cxt->mtd_index < 0)
return;
if (mtd->size < (mtd->erasesize * 2)) {
printk(KERN_ERR "MTD partition %d not big enough for mtdoops\n",
mtd->index);
return;
}
cxt->mtd = mtd;
cxt->oops_pages = mtd->size / OOPS_PAGE_SIZE;
ret = find_next_position(cxt);
if (ret == 1)
mtdoops_prepare(cxt);
printk(KERN_DEBUG "mtdoops: 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;
cxt->mtd = NULL;
flush_scheduled_work();
}
static void
mtdoops_console_write(struct console *co, const char *s, unsigned int count)
{
struct mtdoops_context *cxt = co->data;
struct mtd_info *mtd = cxt->mtd;
int i, ret;
if (!cxt->ready || !mtd)
return;
if (!oops_in_progress && cxt->writecount != 0) {
size_t retlen;
if (cxt->writecount < OOPS_PAGE_SIZE)
memset(cxt->oops_buf + cxt->writecount, 0xff,
OOPS_PAGE_SIZE - cxt->writecount);
ret = mtd->write(mtd, cxt->nextpage * OOPS_PAGE_SIZE,
OOPS_PAGE_SIZE, &retlen, cxt->oops_buf);
cxt->ready = 0;
cxt->writecount = 0;
if ((retlen != OOPS_PAGE_SIZE) || (ret < 0))
printk(KERN_ERR "mtdoops: Write failure at %d (%d of %d"
" written), err %d.\n",
cxt->nextpage * OOPS_PAGE_SIZE, retlen,
OOPS_PAGE_SIZE, ret);
ret = mtdoops_inc_counter(cxt);
if (ret == 1)
schedule_work(&cxt->work);
}
if (!oops_in_progress)
return;
if (cxt->writecount == 0) {
u32 *stamp = cxt->oops_buf;
*stamp = cxt->nextcount;
cxt->writecount = 4;
}
if ((count + cxt->writecount) > OOPS_PAGE_SIZE)
count = OOPS_PAGE_SIZE - cxt->writecount;
for (i = 0; i < count; i++, s++)
*((char *)(cxt->oops_buf) + cxt->writecount + i) = *s;
cxt->writecount = cxt->writecount + count;
}
static int __init mtdoops_console_setup(struct console *co, char *options)
{
struct mtdoops_context *cxt = co->data;
if (cxt->mtd_index != -1)
return -EBUSY;
if (co->index == -1)
return -EINVAL;
cxt->mtd_index = co->index;
return 0;
}
static struct mtd_notifier mtdoops_notifier = {
.add = mtdoops_notify_add,
.remove = mtdoops_notify_remove,
};
static struct console mtdoops_console = {
.name = "ttyMTD",
.write = mtdoops_console_write,
.setup = mtdoops_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
.data = &oops_cxt,
};
static int __init mtdoops_console_init(void)
{
struct mtdoops_context *cxt = &oops_cxt;
cxt->mtd_index = -1;
cxt->oops_buf = vmalloc(OOPS_PAGE_SIZE);
if (!cxt->oops_buf) {
printk(KERN_ERR "Failed to allocate oops buffer workspace\n");
return -ENOMEM;
}
INIT_WORK(&cxt->work, mtdoops_workfunc);
register_console(&mtdoops_console);
register_mtd_user(&mtdoops_notifier);
return 0;
}
static void __exit mtdoops_console_exit(void)
{
struct mtdoops_context *cxt = &oops_cxt;
unregister_mtd_user(&mtdoops_notifier);
unregister_console(&mtdoops_console);
vfree(cxt->oops_buf);
}
subsys_initcall(mtdoops_console_init);
module_exit(mtdoops_console_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Richard Purdie <rpurdie@openedhand.com>");
MODULE_DESCRIPTION("MTD Oops/Panic console logger/driver");