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SubjectRe: [PATCH v2 03/11] pstore/blk: blkoops: support pmsg recorder
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hi Kees Cook,

On 2020/3/19 AM 2:13, Kees Cook wrote:
> On Fri, Feb 07, 2020 at 08:25:47PM +0800, WeiXiong Liao wrote:
>> pmsg support recorder for userspace. To enable pmsg, just make pmsg_size
>> be greater than 0 and a multiple of 4096.
>>
>> Signed-off-by: WeiXiong Liao <liaoweixiong@allwinnertech.com>
>> ---
>> fs/pstore/Kconfig | 12 +++
>> fs/pstore/blkoops.c | 11 +++
>> fs/pstore/blkzone.c | 229 +++++++++++++++++++++++++++++++++++++++++++--
>> include/linux/pstore_blk.h | 4 +
>> 4 files changed, 246 insertions(+), 10 deletions(-)
>>
>> diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
>> index 7a57a8edb612..bbf1fdb5eaa7 100644
>> --- a/fs/pstore/Kconfig
>> +++ b/fs/pstore/Kconfig
>> @@ -186,6 +186,18 @@ config PSTORE_BLKOOPS_DMESG_SIZE
>> NOTE that, both kconfig and module parameters can configure blkoops,
>> but module parameters have priority over kconfig.
>>
>> +config PSTORE_BLKOOPS_PMSG_SIZE
>> + int "pmsg size in kbytes for blkoops"
>> + depends on PSTORE_BLKOOPS
>> + depends on PSTORE_PMSG
>> + default 64
>
> Instead of "depends on PSTORE_PMSG", you can do:
>
> default 64 if PSTORE_PMSG
> default 0
>

What happens if PSTORE_BLKOOPS_PMSG_SIZE is non-zero while
PSTORE_PMSG is disabled? The pmsg recorder do not work but pstore/blk
will always allocate zone for pmsg recorder since pmsg_size is non-zero.
It waste storage space.

I think "depends on PSTORE_PMSG" is batter than "default 64 if PSTORE_PMSG",
because PSTORE_BLKOOPS_PMSG_SIZE really depends on PSTORE_PMSG.

>> + help
>> + This just sets size of pmsg (pmsg_size) for pstore/blk. The size is
>> + in KB and must be a multiple of 4.
>> +
>> + NOTE that, both kconfig and module parameters can configure blkoops,
>> + but module parameters have priority over kconfig.
>> +
>> config PSTORE_BLKOOPS_BLKDEV
>> string "block device for blkoops"
>> depends on PSTORE_BLKOOPS
>> diff --git a/fs/pstore/blkoops.c b/fs/pstore/blkoops.c
>> index 8027c3af8c8d..02e6e4c1f965 100644
>> --- a/fs/pstore/blkoops.c
>> +++ b/fs/pstore/blkoops.c
>> @@ -16,6 +16,10 @@
>> module_param(dmesg_size, long, 0400);
>> MODULE_PARM_DESC(dmesg_size, "demsg size in kbytes");
>>
>> +static long pmsg_size = -1;
>
> Now PSTORE_BLKOOPS_PMSG_SIZE will always be available and you can set it
> here.
>

Note above.

>> +module_param(pmsg_size, long, 0400);
>> +MODULE_PARM_DESC(pmsg_size, "pmsg size in kbytes");
>> +
>> static int dump_oops = -1;
>> module_param(dump_oops, int, 0400);
>> MODULE_PARM_DESC(total_size, "whether dump oops");
>> @@ -60,6 +64,12 @@
>> #define DEFAULT_DMESG_SIZE 0
>> #endif
>>
>> +#ifdef CONFIG_PSTORE_BLKOOPS_PMSG_SIZE
>> +#define DEFAULT_PMSG_SIZE CONFIG_PSTORE_BLKOOPS_PMSG_SIZE
>> +#else
>> +#define DEFAULT_PMSG_SIZE 0
>> +#endif
>
> And drop this.
>

Note above.

>> +
>> #ifdef CONFIG_PSTORE_BLKOOPS_DUMP_OOPS
>> #define DEFAULT_DUMP_OOPS CONFIG_PSTORE_BLKOOPS_DUMP_OOPS
>> #else
>> @@ -113,6 +123,7 @@ int blkoops_register_device(struct blkoops_device *bo_dev)
>> }
>>
>> verify_size(dmesg_size, DEFAULT_DMESG_SIZE, 4096);
>> + verify_size(pmsg_size, DEFAULT_PMSG_SIZE, 4096);
>> #undef verify_size
>> dump_oops = !!(dump_oops < 0 ? DEFAULT_DUMP_OOPS : dump_oops);
>>
>> diff --git a/fs/pstore/blkzone.c b/fs/pstore/blkzone.c
>> index f77f612b50ba..a3464252d52e 100644
>> --- a/fs/pstore/blkzone.c
>> +++ b/fs/pstore/blkzone.c
>> @@ -24,12 +24,14 @@
>> *
>> * @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[];
>> };
>>
>> @@ -85,8 +87,10 @@ struct blkz_zone {
>>
>> struct blkz_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 recover.
>> @@ -119,6 +123,11 @@ 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 blkz_context *cxt = &blkz_cxt;
>> @@ -410,6 +419,69 @@ static int blkz_recover_dmesg(struct blkz_context *cxt)
>> return ret;
>> }
>>
>> +static int blkz_recover_pmsg(struct blkz_context *cxt)
>> +{
>> + struct blkz_info *info = cxt->bzinfo;
>> + struct blkz_buffer *oldbuf;
>> + struct blkz_zone *zone = NULL;
>> + int ret = 0;
>> + ssize_t rcnt, len;
>> +
>> + zone = cxt->pbz;
>> + if (!zone || zone->oldbuf)
>> + return 0;
>> +
>> + if (is_on_panic())
>> + goto out;
>> +
>> + if (unlikely(!info->read))
>> + return -EINVAL;
>> +
>> + len = zone->buffer_size + sizeof(*oldbuf);
>> + oldbuf = kzalloc(len, GFP_KERNEL);
>> + if (!oldbuf)
>> + return -ENOMEM;
>> +
>> + rcnt = info->read((char *)oldbuf, len, zone->off);
>> + if (rcnt != len) {
>> + pr_debug("recover 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:
>> + blkz_flush_dirty_zone(zone);
>> + return 0;
>> +
>> +free_oldbuf:
>> + kfree(oldbuf);
>> + return ret;
>> +}
>> +
>> static inline int blkz_recovery(struct blkz_context *cxt)
>> {
>> int ret = -EBUSY;
>> @@ -421,6 +493,10 @@ static inline int blkz_recovery(struct blkz_context *cxt)
>> if (ret)
>> goto recover_fail;
>>
>> + ret = blkz_recover_pmsg(cxt);
>> + if (ret)
>> + goto recover_fail;
>> +
>> pr_debug("recover end!\n");
>> atomic_set(&cxt->recovered, 1);
>> return 0;
>> @@ -435,9 +511,17 @@ static int blkz_pstore_open(struct pstore_info *psi)
>> struct blkz_context *cxt = psi->data;
>>
>> cxt->dmesg_read_cnt = 0;
>> + cxt->pmsg_read_cnt = 0;
>> 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))
>> @@ -455,6 +539,25 @@ static inline int blkz_dmesg_erase(struct blkz_context *cxt,
>> return blkz_zone_write(zone, FLUSH_META, NULL, 0, 0);
>> }
>>
>> +static inline int blkz_pmsg_erase(struct blkz_context *cxt,
>> + struct blkz_zone *zone)
>> +{
>> + if (unlikely(!blkz_old_ok(zone)))
>> + return 0;
>> +
>> + kfree(zone->oldbuf);
>> + zone->oldbuf = NULL;
>> + /*
>> + * if there are new data in zone buffer, that means the old data
>> + * are already invalid. It is no need to flush 0 (erase) to
>> + * block device.
>> + */
>> + if (!buffer_datalen(zone))
>> + return blkz_zone_write(zone, FLUSH_META, NULL, 0, 0);
>> + blkz_flush_dirty_zone(zone);
>> + return 0;
>> +}
>> +
>> static int blkz_pstore_erase(struct pstore_record *record)
>> {
>> struct blkz_context *cxt = record->psi->data;
>> @@ -462,6 +565,8 @@ static int blkz_pstore_erase(struct pstore_record *record)
>> switch (record->type) {
>> case PSTORE_TYPE_DMESG:
>> return blkz_dmesg_erase(cxt, cxt->dbzs[record->id]);
>> + case PSTORE_TYPE_PMSG:
>> + return blkz_pmsg_erase(cxt, cxt->pbz);
>> default:
>> return -EINVAL;
>> }
>> @@ -482,8 +587,10 @@ static void blkz_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 inline int notrace blkz_dmesg_write_do(struct blkz_context *cxt,
>> @@ -546,6 +653,55 @@ static int notrace blkz_dmesg_write(struct blkz_context *cxt,
>> return 0;
>> }
>>
>> +static int notrace blkz_pmsg_write(struct blkz_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 blkz_pstore_write(struct pstore_record *record)
>> {
>> struct blkz_context *cxt = record->psi->data;
>> @@ -557,6 +713,8 @@ static int notrace blkz_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;
>> }
>> @@ -573,6 +731,13 @@ static struct blkz_zone *blkz_read_next_zone(struct blkz_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;
>> }
>>
>> @@ -611,7 +776,8 @@ static ssize_t blkz_dmesg_read(struct blkz_zone *zone,
>> char *buf = kasprintf(GFP_KERNEL,
>> "%s: Total %d times\n",
>> record->reason == KMSG_DUMP_OOPS ? "Oops" :
>> - "Panic", record->count);
>> + record->reason == KMSG_DUMP_PANIC ? "Panic" :
>> + "Unknown", record->count);
>
> Please use get_reason_str() here.
>

get_reason_str() is marked 'static' on platform.c and pstore/blk only
support oops
and panic, it's no need to check more reason number.

>> hlen = strlen(buf);
>> record->buf = krealloc(buf, hlen + size, GFP_KERNEL);
>> if (!record->buf) {
>> @@ -633,6 +799,29 @@ 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 blkz_pstore_read(struct pstore_record *record)
>> {
>> struct blkz_context *cxt = record->psi->data;
>> @@ -657,6 +846,9 @@ static ssize_t blkz_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;
>> }
>> @@ -712,8 +904,10 @@ 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;
>>
>> @@ -798,17 +992,26 @@ static int blkz_cut_zones(struct blkz_context *cxt)
>> struct blkz_info *info = cxt->bzinfo;
>> unsigned long off = 0;
>> int err;
>> - size_t size;
>> + size_t off_size = 0;
>>
>> - size = info->total_size;
>> - cxt->dbzs = blkz_init_zones(PSTORE_TYPE_DMESG, &off, size,
>> + off_size += info->pmsg_size;
>> + cxt->pbz = blkz_init_zone(PSTORE_TYPE_PMSG, &off, info->pmsg_size);
>> + if (IS_ERR(cxt->pbz)) {
>> + err = PTR_ERR(cxt->pbz);
>> + goto fail_out;
>> + }
>> +
>> + cxt->dbzs = blkz_init_zones(PSTORE_TYPE_DMESG, &off,
>> + info->total_size - off_size,
>> info->dmesg_size, &cxt->dmesg_max_cnt);
>> if (IS_ERR(cxt->dbzs)) {
>> err = PTR_ERR(cxt->dbzs);
>> - goto fail_out;
>> + goto free_pmsg;
>> }
>>
>> return 0;
>> +free_pmsg:
>> + blkz_free_zone(&cxt->pbz);
>> fail_out:
>> return err;
>> }
>> @@ -824,7 +1027,7 @@ int blkz_register(struct blkz_info *info)
>> return -EINVAL;
>> }
>>
>> - if (!info->dmesg_size) {
>> + if (!info->dmesg_size && !info->pmsg_size) {
>> pr_warn("at least one of the records be non-zero\n");
>> return -EINVAL;
>> }
>> @@ -851,6 +1054,7 @@ int blkz_register(struct blkz_info *info)
>>
>> check_size(total_size, 4096);
>> check_size(dmesg_size, SECTOR_SIZE);
>> + check_size(pmsg_size, SECTOR_SIZE);
>>
>> #undef check_size
>>
>> @@ -882,6 +1086,7 @@ int blkz_register(struct blkz_info *info)
>> pr_debug("register %s with properties:\n", info->name);
>> pr_debug("\ttotal size : %ld Bytes\n", info->total_size);
>> pr_debug("\tdmesg size : %ld Bytes\n", info->dmesg_size);
>> + pr_debug("\tpmsg size : %ld Bytes\n", info->pmsg_size);
>>
>> err = blkz_cut_zones(cxt);
>> if (err) {
>> @@ -900,11 +1105,14 @@ int blkz_register(struct blkz_info *info)
>> }
>> cxt->pstore.data = cxt;
>> if (info->dmesg_size)
>> - cxt->pstore.flags = PSTORE_FLAGS_DMESG;
>> + cxt->pstore.flags |= PSTORE_FLAGS_DMESG;
>> + if (info->pmsg_size)
>> + cxt->pstore.flags |= PSTORE_FLAGS_PMSG;
>>
>> - 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" : "");
>
> I'd switch to leading spaces so can leave these strings unchanged as you
> add them:
>
> for%s%s%s\n", info->name,
> cxt->dbzs && cxt->bzinfo->dump_oops ? " Oops" : "",
> cxt->dbzs && cxt->bzinfo->panic_write ? " Panic" : "",
> cxt->pbz ? " Pmsg" : "");
>
> etc

That's a good idea.

>
>>
>> err = pstore_register(&cxt->pstore);
>> if (err) {
>> @@ -940,6 +1148,7 @@ 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 589d276fa4e4..af06be25bd01 100644
>> --- a/include/linux/pstore_blk.h
>> +++ b/include/linux/pstore_blk.h
>> @@ -19,6 +19,9 @@
>> * @dmesg_size:
>> * The size of each zones for dmesg (oops & panic). Zero means disabled,
>> * otherwise, it must be multiple of SECTOR_SIZE(512 Bytes).
>> + * @pmsg_size:
>> + * The size of zone for pmsg. Zero means disabled, othewise, it must be
>> + * multiple of SECTOR_SIZE(512).
>> * @dump_oops:
>> * Dump oops and panic log or only panic.
>> * @read, @write:
>> @@ -50,6 +53,7 @@ struct blkz_info {
>>
>> unsigned long total_size;
>> unsigned long dmesg_size;
>> + unsigned long pmsg_size;
>> int dump_oops;
>> blkz_read_op read;
>> blkz_write_op write;
>> --
>> 1.9.1
>>
>

--
WeiXiong Liao

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