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Date: Thu, 17 Jan 2019 16:17:31 -0800
From: Kees Cook <keescook@...omium.org>
To: liaoweixiong <liaoweixiong@...winnertech.com>
Cc: Anton Vorontsov <anton@...msg.org>,
Colin Cross <ccross@...roid.com>,
Tony Luck <tony.luck@...el.com>,
Jonathan Corbet <corbet@....net>,
Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"David S. Miller" <davem@...emloft.net>,
Andrew Morton <akpm@...ux-foundation.org>,
Nicolas Ferre <nicolas.ferre@...rochip.com>,
Arnd Bergmann <arnd@...db.de>,
"open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC v5 3/4] pstore/blk: support pmsg for pstore block
On Mon, Jan 7, 2019 at 4:01 AM liaoweixiong
<liaoweixiong@...winnertech.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?
-Kees
>
> Signed-off-by: liaoweixiong <liaoweixiong@...winnertech.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
>
--
Kees Cook
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