+ 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@xxxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("MTD Oops/Panic console logger/driver");
