Commit 4b23aff0 authored by Richard Purdie's avatar Richard Purdie Committed by David Woodhouse
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[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: default avatarRichard Purdie <rpurdie@openedhand.com>
Signed-off-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
parent 1100b47e

drivers/mtd/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -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"

drivers/mtd/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

drivers/mtd/mtdoops.c

0 → 100644
+365 −0
Original line number Diff line number Diff line 
/*

 * 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");

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