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Subject: Re: [PATCH v1 11/11] mtd: new support oops logger based on pstore/blk
To:     Vignesh Raghavendra <vigneshr@ti.com>,
        Kees Cook <keescook@chromium.org>,
        Anton Vorontsov <anton@enomsg.org>,
        Colin Cross <ccross@android.com>,
        Tony Luck <tony.luck@intel.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Rob Herring <robh@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc:     linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mtd@lists.infradead.org
References: <1579482233-2672-1-git-send-email-liaoweixiong@allwinnertech.com>
 <1579482233-2672-12-git-send-email-liaoweixiong@allwinnertech.com>
 <de3659ad-10bc-f14c-169d-d004c8726316@ti.com>
From:   liaoweixiong <liaoweixiong@allwinnertech.com>
Message-ID: <bee57965-6160-0979-68ee-d3841a585df9@allwinnertech.com>
Date:   Thu, 23 Jan 2020 15:03:25 +0800
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hi Vignesh Raghavendra,

On 2020/1/23 下午12:24, Vignesh Raghavendra wrote:
> Hi
> 
> On 20/01/20 6:33 am, WeiXiong Liao wrote:
> [...]
>> +static inline int mtdpstore_panic_block_isbad(struct mtdpstore_context *cxt,
>> +		loff_t off)
>> +{
>> +	struct mtd_info *mtd = cxt->mtd;
>> +	u64 blknum = div_u64(off, mtd->erasesize);
>> +
>> +	return test_bit(blknum, cxt->badmap);
>> +}
>> +
>> +static inline void mtdpstore_mark_used(struct mtdpstore_context *cxt,
>> +		loff_t off)
>> +{
>> +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
>> +
>> +	pr_debug("mark zone %llu used\n", zonenum);
> 
> Please replace pr_*() with dev_*() throughout the patch. Device pointer
> should be available via struct mtd_info
> 

OK. I will fix it later. Thank you.

> Regards
> Vignesh
> 
>> +	set_bit(zonenum, cxt->usedmap);
>> +}
>> +
>> +static inline void mtdpstore_mark_unused(struct mtdpstore_context *cxt,
>> +		loff_t off)
>> +{
>> +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
>> +
>> +	pr_debug("mark zone %llu unused\n", zonenum);
>> +	clear_bit(zonenum, cxt->usedmap);
>> +}
>> +
>> +static inline void mtdpstore_block_mark_unused(struct mtdpstore_context *cxt,
>> +		loff_t off)
>> +{
>> +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
>> +	u32 zonecnt = cxt->mtd->erasesize / cxt->bo_info.dmesg_size;
>> +
>> +	while (zonecnt > 0) {
>> +		pr_debug("mark zone %llu unused\n", zonenum);
>> +		clear_bit(zonenum, cxt->usedmap);
>> +		zonenum++;
>> +		zonecnt--;
>> +	}
>> +}
>> +
>> +static inline int mtdpstore_is_used(struct mtdpstore_context *cxt, loff_t off)
>> +{
>> +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
>> +	u64 blknum = div_u64(off, cxt->mtd->erasesize);
>> +
>> +	if (test_bit(blknum, cxt->badmap))
>> +		return true;
>> +	return test_bit(zonenum, cxt->usedmap);
>> +}
>> +
>> +static int mtdpstore_block_is_used(struct mtdpstore_context *cxt,
>> +		loff_t off)
>> +{
>> +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
>> +	u32 zonecnt = cxt->mtd->erasesize / cxt->bo_info.dmesg_size;
>> +
>> +	while (zonecnt > 0) {
>> +		if (test_bit(zonenum, cxt->usedmap))
>> +			return true;
>> +		zonenum++;
>> +		zonecnt--;
>> +	}
>> +	return false;
>> +}
>> +
>> +static int mtdpstore_is_empty(struct mtdpstore_context *cxt, char *buf,
>> +		size_t size)
>> +{
>> +	struct mtd_info *mtd = cxt->mtd;
>> +	size_t sz;
>> +	int i;
>> +
>> +	sz = min_t(uint32_t, size, mtd->writesize / 4);
>> +	for (i = 0; i < sz; i++) {
>> +		if (buf[i] != (char)0xFF)
>> +			return false;
>> +	}
>> +	return true;
>> +}
>> +
>> +static void mtdpstore_mark_removed(struct mtdpstore_context *cxt, loff_t off)
>> +{
>> +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
>> +
>> +	pr_debug("mark zone %llu removed\n", zonenum);
>> +	set_bit(zonenum, cxt->rmmap);
>> +}
>> +
>> +static void mtdpstore_block_clear_removed(struct mtdpstore_context *cxt,
>> +		loff_t off)
>> +{
>> +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
>> +	u32 zonecnt = cxt->mtd->erasesize / cxt->bo_info.dmesg_size;
>> +
>> +	while (zonecnt > 0) {
>> +		clear_bit(zonenum, cxt->rmmap);
>> +		zonenum++;
>> +		zonecnt--;
>> +	}
>> +}
>> +
>> +static int mtdpstore_block_is_removed(struct mtdpstore_context *cxt,
>> +		loff_t off)
>> +{
>> +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
>> +	u32 zonecnt = cxt->mtd->erasesize / cxt->bo_info.dmesg_size;
>> +
>> +	while (zonecnt > 0) {
>> +		if (test_bit(zonenum, cxt->rmmap))
>> +			return true;
>> +		zonenum++;
>> +		zonecnt--;
>> +	}
>> +	return false;
>> +}
>> +
>> +static int mtdpstore_erase_do(struct mtdpstore_context *cxt, loff_t off)
>> +{
>> +	struct erase_info erase;
>> +	int ret;
>> +
>> +	pr_debug("try to erase off 0x%llx\n", off);
>> +	erase.len = cxt->mtd->erasesize;
>> +	erase.addr = off;
>> +	ret = mtd_erase(cxt->mtd, &erase);
>> +	if (!ret)
>> +		mtdpstore_block_clear_removed(cxt, off);
>> +	else
>> +		pr_err("erase of region [0x%llx, 0x%llx] on \"%s\" failed\n",
>> +		       (unsigned long long)erase.addr,
>> +		       (unsigned long long)erase.len, cxt->bo_info.device);
>> +	return ret;
>> +}
>> +
>> +/*
>> + * called while removing file
>> + *
>> + * Avoiding over erasing, do erase only when all zones are removed or unused.
>> + * Ensure to remove when unregister by reading, erasing and wrtiing back.
>> + */
>> +static ssize_t mtdpstore_erase(size_t size, loff_t off)
>> +{
>> +	struct mtdpstore_context *cxt = &oops_cxt;
>> +
>> +	if (mtdpstore_block_isbad(cxt, off))
>> +		return -EIO;
>> +
>> +	mtdpstore_mark_unused(cxt, off);
>> +
>> +	if (likely(mtdpstore_block_is_used(cxt, off))) {
>> +		mtdpstore_mark_removed(cxt, off);
>> +		return 0;
>> +	}
>> +
>> +	/* all zones are unused, erase it */
>> +	off = ALIGN_DOWN(off, cxt->mtd->erasesize);
>> +	return mtdpstore_erase_do(cxt, off);
>> +}
>> +
>> +/*
>> + * What is securety for mtdpstore?
>> + * As there is no erase for panic case, we should ensure at least one zone
>> + * is writable. Otherwise, panic write will be failed.
>> + * If zone is used, write operation will return -ENEXT, which means that
>> + * pstore/blk will try one by one until get a empty zone. So, it's no need
>> + * to ensure next zone is empty, but at least one.
>> + */
>> +static int mtdpstore_security(struct mtdpstore_context *cxt, loff_t off)
>> +{
>> +	int ret = 0, i;
>> +	u32 zonenum = (u32)div_u64(off, cxt->bo_info.dmesg_size);
>> +	u32 zonecnt = (u32)div_u64(cxt->mtd->size, cxt->bo_info.dmesg_size);
>> +	u32 blkcnt = (u32)div_u64(cxt->mtd->size, cxt->mtd->erasesize);
>> +	u32 erasesize = cxt->mtd->erasesize;
>> +
>> +	for (i = 0; i < zonecnt; i++) {
>> +		u32 num = (zonenum + i) % zonecnt;
>> +
>> +		/* found empty zone */
>> +		if (!test_bit(num, cxt->usedmap))
>> +			return 0;
>> +	}
>> +
>> +	/* If there is no any empty zone, we have no way but to do erase */
>> +	off = ALIGN_DOWN(off, erasesize);
>> +	while (blkcnt--) {
>> +		div64_u64_rem(off + erasesize, cxt->mtd->size, (u64 *)&off);
>> +
>> +		if (mtdpstore_block_isbad(cxt, off))
>> +			continue;
>> +
>> +		ret = mtdpstore_erase_do(cxt, off);
>> +		if (!ret) {
>> +			mtdpstore_block_mark_unused(cxt, off);
>> +			break;
>> +		}
>> +	}
>> +
>> +	if (ret)
>> +		pr_err("all blocks bad!\n");
>> +	pr_debug("end security\n");
>> +	return ret;
>> +}
>> +
>> +static ssize_t mtdpstore_write(const char *buf, size_t size, loff_t off)
>> +{
>> +	struct mtdpstore_context *cxt = &oops_cxt;
>> +	size_t retlen;
>> +	int ret;
>> +
>> +	if (mtdpstore_block_isbad(cxt, off))
>> +		return -ENEXT;
>> +
>> +	/* zone is used, please try next one */
>> +	if (mtdpstore_is_used(cxt, off))
>> +		return -ENEXT;
>> +
>> +	pr_debug("try to write off 0x%llx size %zu\n", off, size);
>> +	ret = mtd_write(cxt->mtd, off, size, &retlen, (u_char *)buf);
>> +	if (ret < 0 || retlen != size) {
>> +		pr_err("write failure at %lld (%zu of %zu written), err %d\n",
>> +				off, retlen, size, ret);
>> +		return -EIO;
>> +	}
>> +	mtdpstore_mark_used(cxt, off);
>> +
>> +	mtdpstore_security(cxt, off);
>> +	return retlen;
>> +}
>> +
>> +/*
>> + * All zones will be read as pstore/blk will read zone one by one when do
>> + * recover.
>> + */
>> +static ssize_t mtdpstore_read(char *buf, size_t size, loff_t off)
>> +{
>> +	struct mtdpstore_context *cxt = &oops_cxt;
>> +	size_t retlen;
>> +	int ret;
>> +
>> +	if (mtdpstore_block_isbad(cxt, off))
>> +		return -ENEXT;
>> +
>> +	pr_debug("try to read off 0x%llx size %zu\n", off, size);
>> +	ret = mtd_read(cxt->mtd, off, size, &retlen, (u_char *)buf);
>> +	if ((ret < 0 && !mtd_is_bitflip(ret)) || size != retlen)  {
>> +		pr_err("read failure at %lld (%zu of %zu read), err %d\n",
>> +				off, retlen, size, ret);
>> +		return -EIO;
>> +	}
>> +
>> +	if (mtdpstore_is_empty(cxt, buf, size))
>> +		mtdpstore_mark_unused(cxt, off);
>> +	else
>> +		mtdpstore_mark_used(cxt, off);
>> +
>> +	mtdpstore_security(cxt, off);
>> +	return retlen;
>> +}
>> +
>> +static ssize_t mtdpstore_panic_write(const char *buf, size_t size, loff_t off)
>> +{
>> +	struct mtdpstore_context *cxt = &oops_cxt;
>> +	size_t retlen;
>> +	int ret;
>> +
>> +	if (mtdpstore_panic_block_isbad(cxt, off))
>> +		return -ENEXT;
>> +
>> +	/* zone is used, please try next one */
>> +	if (mtdpstore_is_used(cxt, off))
>> +		return -ENEXT;
>> +
>> +	ret = mtd_panic_write(cxt->mtd, off, size, &retlen, (u_char *)buf);
>> +	if (ret < 0 || size != retlen) {
>> +		pr_err("panic write failure at %lld (%zu of %zu read), err %d\n",
>> +				off, retlen, size, ret);
>> +		return -EIO;
>> +	}
>> +	mtdpstore_mark_used(cxt, off);
>> +
>> +	return retlen;
>> +}
>> +
>> +static void mtdpstore_notify_add(struct mtd_info *mtd)
>> +{
>> +	int ret;
>> +	struct mtdpstore_context *cxt = &oops_cxt;
>> +	struct blkoops_info *info = &cxt->bo_info;
>> +	unsigned long longcnt;
>> +
>> +	if (!strcmp(mtd->name, info->device))
>> +		cxt->index = mtd->index;
>> +
>> +	if (mtd->index != cxt->index || cxt->index < 0)
>> +		return;
>> +
>> +	pr_debug("found matching MTD device %s\n", mtd->name);
>> +
>> +	if (mtd->size < info->dmesg_size * 2) {
>> +		pr_err("MTD partition %d not big enough\n", mtd->index);
>> +		return;
>> +	}
>> +	if (mtd->erasesize < info->dmesg_size) {
>> +		pr_err("eraseblock size of MTD partition %d too small\n",
>> +				mtd->index);
>> +		return;
>> +	}
>> +	if (unlikely(info->dmesg_size % mtd->writesize)) {
>> +		pr_err("record size %lu KB must align to write size %d KB\n",
>> +				info->dmesg_size / 1024,
>> +				mtd->writesize / 1024);
>> +		return;
>> +	}
>> +	if (unlikely(mtd->size > MTDPSTORE_MAX_MTD_SIZE)) {
>> +		pr_err("mtd%d is too large (limit is %d MiB)\n",
>> +				mtd->index,
>> +				MTDPSTORE_MAX_MTD_SIZE / 1024 / 1024);
>> +		return;
>> +	}
>> +
>> +	longcnt = BITS_TO_LONGS(div_u64(mtd->size, info->dmesg_size));
>> +	cxt->rmmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
>> +	cxt->usedmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
>> +
>> +	longcnt = BITS_TO_LONGS(div_u64(mtd->size, mtd->erasesize));
>> +	cxt->badmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
>> +
>> +	cxt->bo_dev.total_size = mtd->size;
>> +	/* just support dmesg right now */
>> +	cxt->bo_dev.flags = BLKOOPS_DEV_SUPPORT_DMESG;
>> +	cxt->bo_dev.read = mtdpstore_read;
>> +	cxt->bo_dev.write = mtdpstore_write;
>> +	cxt->bo_dev.erase = mtdpstore_erase;
>> +	cxt->bo_dev.panic_write = mtdpstore_panic_write;
>> +
>> +	ret = blkoops_register_device(&cxt->bo_dev);
>> +	if (ret) {
>> +		pr_err("mtd%d register to blkoops failed\n", mtd->index);
>> +		return;
>> +	}
>> +	cxt->mtd = mtd;
>> +	pr_info("Attached to MTD device %d\n", mtd->index);
>> +}
>> +
>> +static int mtdpstore_flush_removed_do(struct mtdpstore_context *cxt,
>> +		loff_t off, size_t size)
>> +{
>> +	struct mtd_info *mtd = cxt->mtd;
>> +	u_char *buf;
>> +	int ret;
>> +	size_t retlen;
>> +	struct erase_info erase;
>> +
>> +	buf = kmalloc(mtd->erasesize, GFP_KERNEL);
>> +	if (!buf)
>> +		return -ENOMEM;
>> +
>> +	/* 1st. read to cache */
>> +	ret = mtd_read(mtd, off, mtd->erasesize, &retlen, buf);
>> +	if (ret || retlen != mtd->erasesize)
>> +		goto free;
>> +
>> +	/* 2nd. erase block */
>> +	erase.len = mtd->erasesize;
>> +	erase.addr = off;
>> +	ret = mtd_erase(mtd, &erase);
>> +	if (ret)
>> +		goto free;
>> +
>> +	/* 3rd. write back */
>> +	while (size) {
>> +		unsigned int zonesize = cxt->bo_info.dmesg_size;
>> +
>> +		/* remove must clear used bit */
>> +		if (mtdpstore_is_used(cxt, off))
>> +			mtd_write(mtd, off, zonesize, &retlen, buf);
>> +
>> +		off += zonesize;
>> +		size -= min_t(unsigned int, zonesize, size);
>> +	}
>> +
>> +free:
>> +	kfree(buf);
>> +	return ret;
>> +}
>> +
>> +static int mtdpstore_flush_removed(struct mtdpstore_context *cxt)
>> +{
>> +	struct mtd_info *mtd = cxt->mtd;
>> +	int ret;
>> +	loff_t off;
>> +	u32 blkcnt = (u32)div_u64(mtd->size, mtd->erasesize);
>> +
>> +	for (off = 0; blkcnt > 0; blkcnt--, off += mtd->erasesize) {
>> +		ret = mtdpstore_block_is_removed(cxt, off);
>> +		if (!ret) {
>> +			off += mtd->erasesize;
>> +			continue;
>> +		}
>> +
>> +		ret = mtdpstore_flush_removed_do(cxt, off, mtd->erasesize);
>> +		if (ret)
>> +			return ret;
>> +	}
>> +	return 0;
>> +}
>> +
>> +static void mtdpstore_notify_remove(struct mtd_info *mtd)
>> +{
>> +	struct mtdpstore_context *cxt = &oops_cxt;
>> +
>> +	if (mtd->index != cxt->index || cxt->index < 0)
>> +		return;
>> +
>> +	mtdpstore_flush_removed(cxt);
>> +
>> +	blkoops_unregister_device(&cxt->bo_dev);
>> +	kfree(cxt->badmap);
>> +	kfree(cxt->usedmap);
>> +	kfree(cxt->rmmap);
>> +	cxt->mtd = NULL;
>> +	cxt->index = -1;
>> +}
>> +
>> +static struct mtd_notifier mtdpstore_notifier = {
>> +	.add	= mtdpstore_notify_add,
>> +	.remove	= mtdpstore_notify_remove,
>> +};
>> +
>> +static int __init mtdpstore_init(void)
>> +{
>> +	int ret;
>> +	struct mtdpstore_context *cxt = &oops_cxt;
>> +	struct blkoops_info *info = &cxt->bo_info;
>> +
>> +	ret = blkoops_info(info);
>> +	if (unlikely(ret))
>> +		return ret;
>> +
>> +	if (strlen(info->device) == 0) {
>> +		pr_err("mtd device must be supplied\n");
>> +		return -EINVAL;
>> +	}
>> +	if (!info->dmesg_size) {
>> +		pr_err("no recorder enabled\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	/* Setup the MTD device to use */
>> +	ret = kstrtoint((char *)info->device, 0, &cxt->index);
>> +	if (ret)
>> +		cxt->index = -1;
>> +
>> +	register_mtd_user(&mtdpstore_notifier);
>> +	return 0;
>> +}
>> +module_init(mtdpstore_init);
>> +
>> +static void __exit mtdpstore_exit(void)
>> +{
>> +	unregister_mtd_user(&mtdpstore_notifier);
>> +}
>> +module_exit(mtdpstore_exit);
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("WeiXiong Liao <liaoweixiong@allwinnertech.com>");
>> +MODULE_DESCRIPTION("MTD Oops/Panic console logger/driver");
>>
>