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From:   liaoweixiong <liaoweixiong@allwinnertech.com>
Subject: Re: [RFC v5 3/4] pstore/blk: support pmsg for pstore block
To:     Kees Cook <keescook@chromium.org>
Cc:     Anton Vorontsov <anton@enomsg.org>,
        Colin Cross <ccross@android.com>,
        Tony Luck <tony.luck@intel.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "David S. Miller" <davem@davemloft.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Nicolas Ferre <nicolas.ferre@microchip.com>,
        Arnd Bergmann <arnd@arndb.de>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
References: <1546862462-19640-1-git-send-email-liaoweixiong@allwinnertech.com>
 <1546862462-19640-4-git-send-email-liaoweixiong@allwinnertech.com>
 <CAGXu5jKeAAYDD-sBHmXCSJW3VNTb27AKpWpyCjP4i_g0MwSLDw@mail.gmail.com>
Message-ID: <06553995-8dda-93a2-b142-3ca7fcee60ce@allwinnertech.com>
Date:   Wed, 23 Jan 2019 19:11:53 +0800
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Resend this mail.

On 2019-01-18 08:17, Kees Cook wrote:
> On Mon, Jan 7, 2019 at 4:01 AM liaoweixiong
> <liaoweixiong@allwinnertech.com> wrote:
>>
>> To enable pmsg, just set pmsg_size when block device register blkzone.
> 
> At first pass, this looks like a reasonable extension of blkzone. Is
> it possible to add console, ftrace, etc, too?
> 

I plan to do that on other patch, because i am going to refine the
public codes for all extensions before add console, ftrace, etc. It
takes some time.

> -Kees
> 
>>
>> Signed-off-by: liaoweixiong <liaoweixiong@allwinnertech.com>
>> ---
>>  fs/pstore/blkzone.c        | 254 +++++++++++++++++++++++++++++++++++++++++----
>>  include/linux/pstore_blk.h |   1 +
>>  2 files changed, 233 insertions(+), 22 deletions(-)
>>
>> diff --git a/fs/pstore/blkzone.c b/fs/pstore/blkzone.c
>> index e1b7f26..157f1cfd 100644
>> --- a/fs/pstore/blkzone.c
>> +++ b/fs/pstore/blkzone.c
>> @@ -32,12 +32,14 @@
>>   *
>>   * @sig: signature to indicate header (BLK_SIG xor BLKZONE-type value)
>>   * @datalen: length of data in @data
>> + * @start: offset into @data where the beginning of the stored bytes begin
>>   * @data: zone data.
>>   */
>>  struct blkz_buffer {
>>  #define BLK_SIG (0x43474244) /* DBGC */
>>         uint32_t sig;
>>         atomic_t datalen;
>> +       atomic_t start;
>>         uint8_t data[0];
>>  };
>>
>> @@ -70,6 +72,9 @@ struct blkz_dmesg_header {
>>   *     frontent name for this zone
>>   * @buffer:
>>   *     pointer to data buffer managed by this zone
>> + * @oldbuf:
>> + *     pointer to old data buffer. It is used for single zone such as pmsg,
>> + *     saving the old buffer.
>>   * @buffer_size:
>>   *     bytes in @buffer->data
>>   * @should_recover:
>> @@ -83,6 +88,7 @@ struct blkz_zone {
>>         enum pstore_type_id type;
>>
>>         struct blkz_buffer *buffer;
>> +       struct blkz_buffer *oldbuf;
>>         size_t buffer_size;
>>         bool should_recover;
>>         atomic_t dirty;
>> @@ -90,8 +96,10 @@ struct blkz_zone {
>>
>>  struct blkoops_context {
>>         struct blkz_zone **dbzs;        /* dmesg block zones */
>> +       struct blkz_zone *pbz;          /* Pmsg block zone */
>>         unsigned int dmesg_max_cnt;
>>         unsigned int dmesg_read_cnt;
>> +       unsigned int pmsg_read_cnt;
>>         unsigned int dmesg_write_cnt;
>>         /**
>>          * the counter should be recovered when do recovery
>> @@ -125,6 +133,11 @@ static inline int buffer_datalen(struct blkz_zone *zone)
>>         return atomic_read(&zone->buffer->datalen);
>>  }
>>
>> +static inline int buffer_start(struct blkz_zone *zone)
>> +{
>> +       return atomic_read(&zone->buffer->start);
>> +}
>> +
>>  static inline bool is_on_panic(void)
>>  {
>>         struct blkoops_context *cxt = &blkz_cxt;
>> @@ -394,6 +407,72 @@ static int blkz_recover_dmesg(struct blkoops_context *cxt)
>>         return ret;
>>  }
>>
>> +static int blkz_recover_pmsg(struct blkoops_context *cxt)
>> +{
>> +       struct blkz_info *info = cxt->bzinfo;
>> +       struct blkz_buffer *oldbuf;
>> +       struct blkz_zone *zone = NULL;
>> +       ssize_t (*readop)(char *buf, size_t bytes, loff_t pos);
>> +       int ret = 0;
>> +       ssize_t rcnt, len;
>> +
>> +       zone = cxt->pbz;
>> +       if (!zone || zone->oldbuf)
>> +               return 0;
>> +
>> +       if (is_on_panic())
>> +               goto out;
>> +
>> +       readop = info->read;
>> +       if (unlikely(!readop))
>> +               return -EINVAL;
>> +
>> +       len = zone->buffer_size + sizeof(*oldbuf);
>> +       oldbuf = kzalloc(len, GFP_KERNEL);
>> +       if (!oldbuf)
>> +               return -ENOMEM;
>> +
>> +       rcnt = readop((char *)oldbuf, len, zone->off);
>> +       if (rcnt != len) {
>> +               pr_debug("recovery pmsg failed\n");
>> +               ret = (int)rcnt < 0 ? (int)rcnt : -EIO;
>> +               goto free_oldbuf;
>> +       }
>> +
>> +       if (oldbuf->sig != zone->buffer->sig) {
>> +               pr_debug("no valid data in zone %s\n", zone->name);
>> +               goto free_oldbuf;
>> +       }
>> +
>> +       if (zone->buffer_size < atomic_read(&oldbuf->datalen) ||
>> +               zone->buffer_size < atomic_read(&oldbuf->start)) {
>> +               pr_info("found overtop zone: %s: off %lu, size %zu\n",
>> +                               zone->name, zone->off, zone->buffer_size);
>> +               goto free_oldbuf;
>> +       }
>> +
>> +       if (!atomic_read(&oldbuf->datalen)) {
>> +               pr_debug("found erased zone: %s: id 0, off %lu, size %zu, datalen %d\n",
>> +                               zone->name, zone->off, zone->buffer_size,
>> +                               atomic_read(&oldbuf->datalen));
>> +               kfree(oldbuf);
>> +               goto out;
>> +       }
>> +
>> +       pr_debug("found nice zone: %s: id 0, off %lu, size %zu, datalen %d\n",
>> +                       zone->name, zone->off, zone->buffer_size,
>> +                       atomic_read(&oldbuf->datalen));
>> +       zone->oldbuf = oldbuf;
>> +out:
>> +       if (atomic_read(&zone->dirty))
>> +               blkz_zone_write(zone, FLUSH_ALL, NULL, buffer_datalen(zone), 0);
>> +       return 0;
>> +
>> +free_oldbuf:
>> +       kfree(oldbuf);
>> +       return ret;
>> +}
>> +
>>  static inline int blkz_recovery(struct blkoops_context *cxt)
>>  {
>>         int ret = -EBUSY;
>> @@ -408,6 +487,10 @@ static inline int blkz_recovery(struct blkoops_context *cxt)
>>         if (ret)
>>                 goto recover_fail;
>>
>> +       ret = blkz_recover_pmsg(cxt);
>> +       if (ret)
>> +               goto recover_fail;
>> +
>>         atomic_set(&cxt->recovery, 1);
>>         pr_debug("recover end!\n");
>>         return 0;
>> @@ -425,11 +508,18 @@ static int blkoops_pstore_open(struct pstore_info *psi)
>>         return 0;
>>  }
>>
>> +static inline bool blkz_old_ok(struct blkz_zone *zone)
>> +{
>> +       if (zone && zone->oldbuf && atomic_read(&zone->oldbuf->datalen))
>> +               return true;
>> +       return false;
>> +}
>> +
>>  static inline bool blkz_ok(struct blkz_zone *zone)
>>  {
>> -       if (!zone || !zone->buffer || !buffer_datalen(zone))
>> -               return false;
>> -       return true;
>> +       if (zone && zone->buffer && buffer_datalen(zone))
>> +               return true;
>> +       return false;
>>  }
>>
>>  static int blkoops_pstore_erase(struct pstore_record *record)
>> @@ -443,13 +533,29 @@ static int blkoops_pstore_erase(struct pstore_record *record)
>>          */
>>         blkz_recovery(cxt);
>>
>> -       if (record->type == PSTORE_TYPE_DMESG)
>> +       if (record->type == PSTORE_TYPE_DMESG) {
>>                 zone = cxt->dbzs[record->id];
>> -       if (!blkz_ok(zone))
>> -               return 0;
>> +               if (unlikely(!blkz_ok(zone)))
>> +                       return 0;
>>
>> -       atomic_set(&zone->buffer->datalen, 0);
>> -       return blkz_zone_write(zone, FLUSH_META, NULL, 0, 0);
>> +               atomic_set(&zone->buffer->datalen, 0);
>> +               return blkz_zone_write(zone, FLUSH_META, NULL, 0, 0);
>> +       } else if (record->type == PSTORE_TYPE_PMSG) {
>> +               zone = cxt->pbz;
>> +               if (unlikely(!blkz_old_ok(zone)))
>> +                       return 0;
>> +
>> +               kfree(zone->oldbuf);
>> +               zone->oldbuf = NULL;
>> +               /**
>> +                * if there is new data in zone buffer, there is no need to
>> +                * flush 0 (erase) to block device
>> +                */
>> +               if (buffer_datalen(zone))
>> +                       return 0;
>> +               return blkz_zone_write(zone, FLUSH_META, NULL, 0, 0);
>> +       }
>> +       return -EINVAL;
>>  }
>>
>>  static void blkoops_write_kmsg_hdr(struct blkz_zone *zone,
>> @@ -467,8 +573,10 @@ static void blkoops_write_kmsg_hdr(struct blkz_zone *zone,
>>         hdr->reason = record->reason;
>>         if (hdr->reason == KMSG_DUMP_OOPS)
>>                 hdr->counter = ++cxt->oops_counter;
>> -       else
>> +       else if (hdr->reason == KMSG_DUMP_PANIC)
>>                 hdr->counter = ++cxt->panic_counter;
>> +       else
>> +               hdr->counter = 0;
>>  }
>>
>>  static int notrace blkz_dmesg_write(struct blkoops_context *cxt,
>> @@ -518,6 +626,55 @@ static int notrace blkz_dmesg_write(struct blkoops_context *cxt,
>>         return 0;
>>  }
>>
>> +static int notrace blkz_pmsg_write(struct blkoops_context *cxt,
>> +               struct pstore_record *record)
>> +{
>> +       struct blkz_zone *zone;
>> +       size_t start, rem;
>> +       int cnt = record->size;
>> +       bool is_full_data = false;
>> +       char *buf = record->buf;
>> +
>> +       zone = cxt->pbz;
>> +       if (!zone)
>> +               return -ENOSPC;
>> +
>> +       if (atomic_read(&zone->buffer->datalen) >= zone->buffer_size)
>> +               is_full_data = true;
>> +
>> +       if (unlikely(cnt > zone->buffer_size)) {
>> +               buf += cnt - zone->buffer_size;
>> +               cnt = zone->buffer_size;
>> +       }
>> +
>> +       start = buffer_start(zone);
>> +       rem = zone->buffer_size - start;
>> +       if (unlikely(rem < cnt)) {
>> +               blkz_zone_write(zone, FLUSH_PART, buf, rem, start);
>> +               buf += rem;
>> +               cnt -= rem;
>> +               start = 0;
>> +               is_full_data = true;
>> +       }
>> +
>> +       atomic_set(&zone->buffer->start, cnt + start);
>> +       blkz_zone_write(zone, FLUSH_PART, buf, cnt, start);
>> +
>> +       /**
>> +        * blkz_zone_write will set datalen as start + cnt.
>> +        * It work if actual data length lesser than buffer size.
>> +        * If data length greater than buffer size, pmsg will rewrite to
>> +        * beginning of zone, which make buffer->datalen wrongly.
>> +        * So we should reset datalen as buffer size once actual data length
>> +        * greater than buffer size.
>> +        */
>> +       if (is_full_data) {
>> +               atomic_set(&zone->buffer->datalen, zone->buffer_size);
>> +               blkz_zone_write(zone, FLUSH_META, NULL, 0, 0);
>> +       }
>> +       return 0;
>> +}
>> +
>>  static int notrace blkoops_pstore_write(struct pstore_record *record)
>>  {
>>         struct blkoops_context *cxt = record->psi->data;
>> @@ -535,6 +692,8 @@ static int notrace blkoops_pstore_write(struct pstore_record *record)
>>         switch (record->type) {
>>         case PSTORE_TYPE_DMESG:
>>                 return blkz_dmesg_write(cxt, record);
>> +       case PSTORE_TYPE_PMSG:
>> +               return blkz_pmsg_write(cxt, record);
>>         default:
>>                 return -EINVAL;
>>         }
>> @@ -551,6 +710,13 @@ static struct blkz_zone *blkz_read_next_zone(struct blkoops_context *cxt)
>>                         return zone;
>>         }
>>
>> +       if (cxt->pmsg_read_cnt == 0) {
>> +               cxt->pmsg_read_cnt++;
>> +               zone = cxt->pbz;
>> +               if (blkz_old_ok(zone))
>> +                       return zone;
>> +       }
>> +
>>         return NULL;
>>  }
>>
>> @@ -589,7 +755,8 @@ static ssize_t blkz_dmesg_read(struct blkz_zone *zone,
>>                 char *buf = kasprintf(GFP_KERNEL,
>>                                 "blkoops: %s: Total %d times\n",
>>                                 record->reason == KMSG_DUMP_OOPS ? "Oops" :
>> -                               "Panic", record->count);
>> +                               record->reason == KMSG_DUMP_PANIC ? "Panic" :
>> +                               "Unknown", record->count);
>>                 hlen = strlen(buf);
>>                 record->buf = krealloc(buf, hlen + size, GFP_KERNEL);
>>                 if (!record->buf) {
>> @@ -611,6 +778,29 @@ static ssize_t blkz_dmesg_read(struct blkz_zone *zone,
>>         return size + hlen;
>>  }
>>
>> +static ssize_t blkz_pmsg_read(struct blkz_zone *zone,
>> +               struct pstore_record *record)
>> +{
>> +       size_t size, start;
>> +       struct blkz_buffer *buf;
>> +
>> +       buf = (struct blkz_buffer *)zone->oldbuf;
>> +       if (!buf)
>> +               return READ_NEXT_ZONE;
>> +
>> +       size = atomic_read(&buf->datalen);
>> +       start = atomic_read(&buf->start);
>> +
>> +       record->buf = kmalloc(size, GFP_KERNEL);
>> +       if (!record->buf)
>> +               return -ENOMEM;
>> +
>> +       memcpy(record->buf, buf->data + start, size - start);
>> +       memcpy(record->buf + size - start, buf->data, start);
>> +
>> +       return size;
>> +}
>> +
>>  static ssize_t blkoops_pstore_read(struct pstore_record *record)
>>  {
>>         struct blkoops_context *cxt = record->psi->data;
>> @@ -642,6 +832,9 @@ static ssize_t blkoops_pstore_read(struct pstore_record *record)
>>                 blkz_read = blkz_dmesg_read;
>>                 record->id = cxt->dmesg_read_cnt - 1;
>>                 break;
>> +       case PSTORE_TYPE_PMSG:
>> +               blkz_read = blkz_pmsg_read;
>> +               break;
>>         default:
>>                 goto next_zone;
>>         }
>> @@ -754,8 +947,10 @@ static struct blkz_zone *blkz_init_zone(enum pstore_type_id type,
>>         zone->type = type;
>>         zone->buffer_size = size - sizeof(struct blkz_buffer);
>>         zone->buffer->sig = type ^ BLK_SIG;
>> +       zone->oldbuf = NULL;
>>         atomic_set(&zone->dirty, 0);
>>         atomic_set(&zone->buffer->datalen, 0);
>> +       atomic_set(&zone->buffer->start, 0);
>>
>>         *off += size;
>>
>> @@ -837,7 +1032,7 @@ static int blkz_cut_zones(struct blkoops_context *cxt)
>>         int err;
>>         size_t size;
>>
>> -       size = info->part_size;
>> +       size = info->part_size - info->pmsg_size;
>>         cxt->dbzs = blkz_init_zones(PSTORE_TYPE_DMESG, &off, size,
>>                         info->dmesg_size, &cxt->dmesg_max_cnt);
>>         if (IS_ERR(cxt->dbzs)) {
>> @@ -845,7 +1040,16 @@ static int blkz_cut_zones(struct blkoops_context *cxt)
>>                 goto fail_out;
>>         }
>>
>> +       size = info->pmsg_size;
>> +       cxt->pbz = blkz_init_zone(PSTORE_TYPE_PMSG, &off, size);
>> +       if (IS_ERR(cxt->pbz)) {
>> +               err = PTR_ERR(cxt->pbz);
>> +               goto free_dmesg_zones;
>> +       }
>> +
>>         return 0;
>> +free_dmesg_zones:
>> +       blkz_free_zones(&cxt->dbzs, &cxt->dmesg_max_cnt);
>>  fail_out:
>>         return err;
>>  }
>> @@ -856,7 +1060,7 @@ int blkz_register(struct blkz_info *info)
>>         struct blkoops_context *cxt = &blkz_cxt;
>>         struct module *owner = info->owner;
>>
>> -       if (!info->part_size || !info->dmesg_size) {
>> +       if (!info->part_size || (!info->dmesg_size && !info->pmsg_size)) {
>>                 pr_warn("The memory size and the dmesg size must be non-zero\n");
>>                 return -EINVAL;
>>         }
>> @@ -876,6 +1080,7 @@ int blkz_register(struct blkz_info *info)
>>
>>         check_size(part_size, 4096 - 1);
>>         check_size(dmesg_size, SECTOR_SIZE - 1);
>> +       check_size(pmsg_size, SECTOR_SIZE - 1);
>>
>>  #undef check_size
>>
>> @@ -902,16 +1107,20 @@ int blkz_register(struct blkz_info *info)
>>                 goto fail_out;
>>         }
>>
>> -       cxt->pstore.bufsize = cxt->dbzs[0]->buffer_size -
>> +       if (info->dmesg_size) {
>> +               cxt->pstore.bufsize = cxt->dbzs[0]->buffer_size -
>>                         sizeof(struct blkz_dmesg_header);
>> -       cxt->pstore.buf = kzalloc(cxt->pstore.bufsize, GFP_KERNEL);
>> -       if (!cxt->pstore.buf) {
>> -               pr_err("cannot allocate pstore crash dump buffer\n");
>> -               err = -ENOMEM;
>> -               goto fail_out;
>> +               cxt->pstore.buf = kzalloc(cxt->pstore.bufsize, GFP_KERNEL);
>> +               if (!cxt->pstore.buf) {
>> +                       err = -ENOMEM;
>> +                       goto fail_out;
>> +               }
>>         }
>>         cxt->pstore.data = cxt;
>> -       cxt->pstore.flags = PSTORE_FLAGS_DMESG;
>> +       if (info->dmesg_size)
>> +               cxt->pstore.flags |= PSTORE_FLAGS_DMESG;
>> +       if (info->pmsg_size)
>> +               cxt->pstore.flags |= PSTORE_FLAGS_PMSG;
>>
>>         err = pstore_register(&cxt->pstore);
>>         if (err) {
>> @@ -919,9 +1128,10 @@ int blkz_register(struct blkz_info *info)
>>                 goto free_pstore_buf;
>>         }
>>
>> -       pr_info("Registered %s as blkzone backend for %s%s\n", info->name,
>> +       pr_info("Registered %s as blkzone backend for %s%s%s\n", info->name,
>>                         cxt->dbzs && cxt->bzinfo->dump_oops ? "Oops " : "",
>> -                       cxt->dbzs && cxt->bzinfo->panic_write ? "Panic " : "");
>> +                       cxt->dbzs && cxt->bzinfo->panic_write ? "Panic " : "",
>> +                       cxt->pbz ? "Pmsg" : "");
>>
>>         module_put(owner);
>>         return 0;
>> @@ -949,7 +1159,7 @@ void blkz_unregister(struct blkz_info *info)
>>         spin_unlock(&cxt->bzinfo_lock);
>>
>>         blkz_free_zones(&cxt->dbzs, &cxt->dmesg_max_cnt);
>> -
>> +       blkz_free_zone(&cxt->pbz);
>>  }
>>  EXPORT_SYMBOL_GPL(blkz_unregister);
>>
>> diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
>> index 426cae4..6c6b4eb 100644
>> --- a/include/linux/pstore_blk.h
>> +++ b/include/linux/pstore_blk.h
>> @@ -48,6 +48,7 @@ struct blkz_info {
>>         const char *part_path;
>>         unsigned long part_size;
>>         unsigned long dmesg_size;
>> +       unsigned long pmsg_size;
>>         int dump_oops;
>>         ssize_t (*read)(char *buf, size_t bytes, loff_t pos);
>>         ssize_t (*write)(const char *buf, size_t bytes, loff_t pos);
>> --
>> 1.9.1
>>
> 
>