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). http://folks.o-hand.com/richard/oopslog.c is an example of extracting this information in userspace. It will work with an mtdblock device or a dump of an mtd partition. Signed-off-by: Richard Purdie <[EMAIL PROTECTED]> --- drivers/mtd/Kconfig | 8 + drivers/mtd/Makefile | 1 drivers/mtd/mtdoops.c | 365 ++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 374 insertions(+) Index: linux/drivers/mtd/Kconfig =================================================================== --- linux.orig/drivers/mtd/Kconfig 2007-05-13 12:30:39.000000000 +0100 +++ linux/drivers/mtd/Kconfig 2007-05-29 11:16:29.000000000 +0100 @@ -278,6 +278,15 @@ 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. Add console=ttyMTDx to the commandline to activate + (where x is the MTD partition number to use). + source "drivers/mtd/chips/Kconfig" source "drivers/mtd/maps/Kconfig" Index: linux/drivers/mtd/Makefile =================================================================== --- linux.orig/drivers/mtd/Makefile 2007-05-10 10:21:28.000000000 +0100 +++ linux/drivers/mtd/Makefile 2007-05-29 11:16:51.000000000 +0100 @@ -23,6 +23,7 @@ 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 Index: linux/drivers/mtd/mtdoops.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux/drivers/mtd/mtdoops.c 2007-05-29 11:16:29.000000000 +0100 @@ -0,0 +1,365 @@ +/* + * MTD Oops/Panic logger + * + * Copyright (C) 2007 Nokia Corporation. All rights reserved. + * + * Author: Richard Purdie <[EMAIL PROTECTED]> + * + * 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 <[EMAIL PROTECTED]>"); +MODULE_DESCRIPTION("MTD Oops/Panic console logger/driver"); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
