Re: [PATCH v2 03/11] pstore/blk: blkoops: support pmsg recorder
From: Kees Cook
Date: Wed Mar 18 2020 - 14:13:19 EST
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@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 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
> + 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.
> +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.
> +
> #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.
> 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
>
> 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
>
--
Kees Cook