[PATCH 03/11] pstore/blk: support pmsg recorder

From: WeiXiong Liao
Date: Thu Jan 16 2020 - 05:01:37 EST

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@xxxxxxxxxxxxxxxxx>
---
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 cd15f9322acd..656d63dc3f01 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
+ help
+ This just sets size of pmsg (pmsg_size) for pstore/blk. The value must
+ be a multiple of 4096.
+
+ 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 69904fdeab6b..846ba8bc930f 100644
--- a/fs/pstore/blkoops.c
+++ b/fs/pstore/blkoops.c
@@ -31,6 +31,10 @@
module_param(dmesg_size, long, 0400);
MODULE_PARM_DESC(dmesg_size, "demsg size in kbytes");

+static long pmsg_size = -1;
+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");
@@ -75,6 +79,12 @@
#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
+
#ifdef CONFIG_PSTORE_BLKOOPS_DUMP_OOPS
#define DEFAULT_DUMP_OOPS CONFIG_PSTORE_BLKOOPS_DUMP_OOPS
#else
@@ -128,6 +138,7 @@ 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 1eb681350612..8716c51d7f98 100644
--- a/fs/pstore/blkzone.c
+++ b/fs/pstore/blkzone.c
@@ -40,12 +40,14 @@
*
* @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[];
};

@@ -101,8 +103,10 @@ 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.
@@ -135,6 +139,11 @@ 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;
@@ -425,6 +434,69 @@ 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;
@@ -436,6 +508,10 @@ 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;
@@ -450,9 +526,17 @@ 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))
@@ -470,6 +554,25 @@ 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;
@@ -477,6 +580,8 @@ 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;
}
@@ -497,8 +602,10 @@ 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,
@@ -561,6 +668,55 @@ 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;
@@ -572,6 +728,8 @@ 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;
}
@@ -588,6 +746,13 @@ 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;
}

@@ -626,7 +791,8 @@ 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);
hlen = strlen(buf);
record->buf = krealloc(buf, hlen + size, GFP_KERNEL);
if (!record->buf) {
@@ -648,6 +814,29 @@ 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;
@@ -672,6 +861,9 @@ 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;
}
@@ -727,8 +919,10 @@ 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;

@@ -813,17 +1007,26 @@ 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;
}
@@ -839,7 +1042,7 @@ 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;
}
@@ -866,6 +1069,7 @@ 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

@@ -897,6 +1101,7 @@ 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) {
@@ -915,11 +1120,14 @@ 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" : "");

err = pstore_register(&cxt->pstore);
if (err) {
@@ -955,6 +1163,7 @@ 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