Re: [PATCH v2 04/11] pstore/blk: blkoops: support console recorder

[Kees Cook <keescook@xxxxxxxxxxxx>]

On Fri, Feb 07, 2020 at 08:25:48PM +0800, WeiXiong Liao wrote:
> Support recorder for console. To enable console recorder, just make
> console_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        | 101 ++++++++++++++++++++++++++++++++++-----------
>  include/linux/blkoops.h    |   6 ++-
>  include/linux/pstore_blk.h |   8 +++-
>  5 files changed, 112 insertions(+), 26 deletions(-)
> 
> diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
> index bbf1fdb5eaa7..5f0a42823028 100644
> --- a/fs/pstore/Kconfig
> +++ b/fs/pstore/Kconfig
> @@ -198,6 +198,18 @@ config PSTORE_BLKOOPS_PMSG_SIZE
>  	  NOTE that, both kconfig and module parameters can configure blkoops,
>  	  but module parameters have priority over kconfig.
>  
> +config PSTORE_BLKOOPS_CONSOLE_SIZE
> +	int "console size in kbytes for blkoops"
> +	depends on PSTORE_BLKOOPS
> +	depends on PSTORE_CONSOLE
> +	default 64

Same tricks here as for the PMSG.

> +	help
> +	  This just sets size of console (console_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 02e6e4c1f965..05990bc3b168 100644
> --- a/fs/pstore/blkoops.c
> +++ b/fs/pstore/blkoops.c
> @@ -20,6 +20,10 @@
>  module_param(pmsg_size, long, 0400);
>  MODULE_PARM_DESC(pmsg_size, "pmsg size in kbytes");
>  
> +static long console_size = -1;
> +module_param(console_size, long, 0400);
> +MODULE_PARM_DESC(console_size, "console size in kbytes");
> +
>  static int dump_oops = -1;
>  module_param(dump_oops, int, 0400);
>  MODULE_PARM_DESC(total_size, "whether dump oops");
> @@ -70,6 +74,12 @@
>  #define DEFAULT_PMSG_SIZE 0
>  #endif
>  
> +#ifdef CONFIG_PSTORE_BLKOOPS_CONSOLE_SIZE
> +#define DEFAULT_CONSOLE_SIZE CONFIG_PSTORE_BLKOOPS_CONSOLE_SIZE
> +#else
> +#define DEFAULT_CONSOLE_SIZE 0
> +#endif
> +
>  #ifdef CONFIG_PSTORE_BLKOOPS_DUMP_OOPS
>  #define DEFAULT_DUMP_OOPS CONFIG_PSTORE_BLKOOPS_DUMP_OOPS
>  #else
> @@ -124,6 +134,7 @@ 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);
> +	verify_size(console_size, DEFAULT_CONSOLE_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 a3464252d52e..9a7e9b06ccf7 100644
> --- a/fs/pstore/blkzone.c
> +++ b/fs/pstore/blkzone.c
> @@ -88,9 +88,11 @@ struct blkz_zone {
>  struct blkz_context {
>  	struct blkz_zone **dbzs;	/* dmesg block zones */
>  	struct blkz_zone *pbz;		/* Pmsg block zone */
> +	struct blkz_zone *cbz;		/* console block zone */
>  	unsigned int dmesg_max_cnt;
>  	unsigned int dmesg_read_cnt;
>  	unsigned int pmsg_read_cnt;
> +	unsigned int console_read_cnt;
>  	unsigned int dmesg_write_cnt;
>  	/*
>  	 * the counter should be recovered when recover.
> @@ -111,6 +113,9 @@ struct blkz_context {
>  };
>  static struct blkz_context blkz_cxt;
>  
> +static void blkz_flush_all_dirty_zones(struct work_struct *);
> +static DECLARE_WORK(blkz_cleaner, blkz_flush_all_dirty_zones);
> +
>  enum blkz_flush_mode {
>  	FLUSH_NONE = 0,
>  	FLUSH_PART,
> @@ -200,6 +205,9 @@ static int blkz_zone_write(struct blkz_zone *zone,
>  	return 0;
>  set_dirty:
>  	atomic_set(&zone->dirty, true);
> +	/* flush dirty zones nicely */
> +	if (wcnt == -EBUSY && !is_on_panic())
> +		schedule_work(&blkz_cleaner);
>  	return -EBUSY;
>  }
>  
> @@ -266,6 +274,15 @@ static int blkz_move_zone(struct blkz_zone *old, struct blkz_zone *new)
>  	return 0;
>  }
>  
> +static void blkz_flush_all_dirty_zones(struct work_struct *work)
> +{
> +	struct blkz_context *cxt = &blkz_cxt;
> +
> +	blkz_flush_dirty_zone(cxt->pbz);
> +	blkz_flush_dirty_zone(cxt->cbz);
> +	blkz_flush_dirty_zones(cxt->dbzs, cxt->dmesg_max_cnt);
> +}
> +
>  static int blkz_recover_dmesg_data(struct blkz_context *cxt)
>  {
>  	struct blkz_info *info = cxt->bzinfo;
> @@ -419,15 +436,13 @@ static int blkz_recover_dmesg(struct blkz_context *cxt)
>  	return ret;
>  }
>  
> -static int blkz_recover_pmsg(struct blkz_context *cxt)
> +static int blkz_recover_zone(struct blkz_context *cxt, struct blkz_zone *zone)
>  {
>  	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;
>  
> @@ -493,7 +508,11 @@ static inline int blkz_recovery(struct blkz_context *cxt)
>  	if (ret)
>  		goto recover_fail;
>  
> -	ret = blkz_recover_pmsg(cxt);
> +	ret = blkz_recover_zone(cxt, cxt->pbz);
> +	if (ret)
> +		goto recover_fail;
> +
> +	ret = blkz_recover_zone(cxt, cxt->cbz);
>  	if (ret)
>  		goto recover_fail;
>  
> @@ -512,6 +531,7 @@ static int blkz_pstore_open(struct pstore_info *psi)
>  
>  	cxt->dmesg_read_cnt = 0;
>  	cxt->pmsg_read_cnt = 0;
> +	cxt->console_read_cnt = 0;
>  	return 0;
>  }
>  
> @@ -539,7 +559,7 @@ 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,
> +static inline int blkz_record_erase(struct blkz_context *cxt,
>  		struct blkz_zone *zone)
>  {
>  	if (unlikely(!blkz_old_ok(zone)))
> @@ -566,9 +586,10 @@ static int blkz_pstore_erase(struct pstore_record *record)
>  	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;
> +		return blkz_record_erase(cxt, cxt->pbz);
> +	case PSTORE_TYPE_CONSOLE:
> +		return blkz_record_erase(cxt, cxt->cbz);
> +	default: return -EINVAL;
>  	}
>  }
>  
> @@ -653,17 +674,15 @@ 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)
> +static int notrace blkz_record_write(struct blkz_context *cxt,
> +		struct blkz_zone *zone, struct pstore_record *record)

How about generalizing this earlier in the patch series instead of
mutating it here?

>  {
> -	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)
> +	if (!zone || !record)
>  		return -ENOSPC;
>  
>  	if (atomic_read(&zone->buffer->datalen) >= zone->buffer_size)
> @@ -710,11 +729,20 @@ static int notrace blkz_pstore_write(struct pstore_record *record)
>  			record->reason == KMSG_DUMP_PANIC)
>  		atomic_set(&cxt->on_panic, 1);
>  
> +	/*
> +	 * if on panic, do not write except dmesg records
> +	 * Fix case that panic_write prints log which wakes up console recorder.
> +	 */
> +	if (is_on_panic() && record->type != PSTORE_TYPE_DMESG)
> +		return -EBUSY;
> +
>  	switch (record->type) {
>  	case PSTORE_TYPE_DMESG:
>  		return blkz_dmesg_write(cxt, record);
> +	case PSTORE_TYPE_CONSOLE:
> +		return blkz_record_write(cxt, cxt->cbz, record);
>  	case PSTORE_TYPE_PMSG:
> -		return blkz_pmsg_write(cxt, record);
> +		return blkz_record_write(cxt, cxt->pbz, record);
>  	default:
>  		return -EINVAL;
>  	}
> @@ -738,6 +766,13 @@ static struct blkz_zone *blkz_read_next_zone(struct blkz_context *cxt)
>  			return zone;
>  	}
>  
> +	if (cxt->console_read_cnt == 0) {
> +		cxt->console_read_cnt++;
> +		zone = cxt->cbz;
> +		if (blkz_old_ok(zone))
> +			return zone;
> +	}
> +
>  	return NULL;
>  }
>  
> @@ -799,7 +834,7 @@ static ssize_t blkz_dmesg_read(struct blkz_zone *zone,
>  	return size + hlen;
>  }
>  
> -static ssize_t blkz_pmsg_read(struct blkz_zone *zone,
> +static ssize_t blkz_record_read(struct blkz_zone *zone,
>  		struct pstore_record *record)
>  {
>  	size_t size, start;
> @@ -825,7 +860,7 @@ static ssize_t blkz_pmsg_read(struct blkz_zone *zone,
>  static ssize_t blkz_pstore_read(struct pstore_record *record)
>  {
>  	struct blkz_context *cxt = record->psi->data;
> -	ssize_t (*blkz_read)(struct blkz_zone *zone,
> +	ssize_t (*readop)(struct blkz_zone *zone,
>  			struct pstore_record *record);
>  	struct blkz_zone *zone;
>  	ssize_t ret;
> @@ -843,17 +878,19 @@ static ssize_t blkz_pstore_read(struct pstore_record *record)
>  	record->type = zone->type;
>  	switch (record->type) {
>  	case PSTORE_TYPE_DMESG:
> -		blkz_read = blkz_dmesg_read;
> +		readop = blkz_dmesg_read;
>  		record->id = cxt->dmesg_read_cnt - 1;
>  		break;
> +	case PSTORE_TYPE_CONSOLE:
> +		/* fallthrough */

Since this case has no body, you can leave off the "fallthrough". (But
if you want to mark it anyway, please use "fallthrough;" instead of a
comment.)

>  	case PSTORE_TYPE_PMSG:
> -		blkz_read = blkz_pmsg_read;
> +		readop = blkz_record_read;
>  		break;
>  	default:
>  		goto next_zone;
>  	}
>  
> -	ret = blkz_read(zone, record);
> +	ret = readop(zone, record);
>  	if (ret == READ_NEXT_ZONE)
>  		goto next_zone;
>  	return ret;
> @@ -1001,15 +1038,25 @@ static int blkz_cut_zones(struct blkz_context *cxt)
>  		goto fail_out;
>  	}
>  
> +	off_size += info->console_size;
> +	cxt->cbz = blkz_init_zone(PSTORE_TYPE_CONSOLE, &off,
> +			info->console_size);
> +	if (IS_ERR(cxt->cbz)) {
> +		err = PTR_ERR(cxt->cbz);
> +		goto free_pmsg;
> +	}
> +
>  	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 free_pmsg;
> +		goto free_console;
>  	}
>  
>  	return 0;
> +free_console:
> +	blkz_free_zone(&cxt->cbz);
>  free_pmsg:
>  	blkz_free_zone(&cxt->pbz);
>  fail_out:
> @@ -1027,7 +1074,7 @@ int blkz_register(struct blkz_info *info)
>  		return -EINVAL;
>  	}
>  
> -	if (!info->dmesg_size && !info->pmsg_size) {
> +	if (!info->dmesg_size && !info->pmsg_size && !info->console_size) {
>  		pr_warn("at least one of the records be non-zero\n");
>  		return -EINVAL;
>  	}
> @@ -1055,6 +1102,7 @@ int blkz_register(struct blkz_info *info)
>  	check_size(total_size, 4096);
>  	check_size(dmesg_size, SECTOR_SIZE);
>  	check_size(pmsg_size, SECTOR_SIZE);
> +	check_size(console_size, SECTOR_SIZE);
>  
>  #undef check_size
>  
> @@ -1087,6 +1135,7 @@ int blkz_register(struct blkz_info *info)
>  	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);
> +	pr_debug("\tconsole size : %ld Bytes\n", info->console_size);
>  
>  	err = blkz_cut_zones(cxt);
>  	if (err) {
> @@ -1108,11 +1157,15 @@ int blkz_register(struct blkz_info *info)
>  		cxt->pstore.flags |= PSTORE_FLAGS_DMESG;
>  	if (info->pmsg_size)
>  		cxt->pstore.flags |= PSTORE_FLAGS_PMSG;
> +	if (info->console_size)
> +		cxt->pstore.flags |= PSTORE_FLAGS_CONSOLE;
>  
> -	pr_info("Registered %s as blkzone backend for %s%s%s\n", info->name,
> +	pr_info("Registered %s as blkzone backend for %s%s%s%s\n",
> +			info->name,
>  			cxt->dbzs && cxt->bzinfo->dump_oops ? "Oops " : "",
>  			cxt->dbzs && cxt->bzinfo->panic_write ? "Panic " : "",
> -			cxt->pbz ? "Pmsg" : "");
> +			cxt->pbz ? "Pmsg " : "",
> +			cxt->cbz ? "Console" : "");
>  
>  	err = pstore_register(&cxt->pstore);
>  	if (err) {
> @@ -1139,6 +1192,8 @@ void blkz_unregister(struct blkz_info *info)
>  {
>  	struct blkz_context *cxt = &blkz_cxt;
>  
> +	flush_work(&blkz_cleaner);
> +
>  	pstore_unregister(&cxt->pstore);
>  	kfree(cxt->pstore.buf);
>  	cxt->pstore.bufsize = 0;
> diff --git a/include/linux/blkoops.h b/include/linux/blkoops.h
> index fe63739309aa..8f40f225545d 100644
> --- a/include/linux/blkoops.h
> +++ b/include/linux/blkoops.h
> @@ -23,8 +23,10 @@
>   *	Both of the @size and @offset parameters on this interface are
>   *	the relative size of the space provided, not the whole disk/flash.
>   *
> - *	On success, the number of bytes read should be returned.
> - *	On error, negative number should be returned.
> + *	On success, the number of bytes read/write should be returned.
> + *	On error, negative number should be returned. The following returning
> + *	number means more:
> + *	  -EBUSY: pstore/blk should try again later.
>   * @panic_write:
>   *	The write operation only used for panic.
>   *
> diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
> index af06be25bd01..546375e04419 100644
> --- a/include/linux/pstore_blk.h
> +++ b/include/linux/pstore_blk.h
> @@ -22,6 +22,9 @@
>   * @pmsg_size:
>   *	The size of zone for pmsg. Zero means disabled, othewise, it must be
>   *	multiple of SECTOR_SIZE(512).
> + * @console_size:
> + *	The size of zone for console. Zero means disabled, othewise, it must
> + *	be multiple of SECTOR_SIZE(512).
>   * @dump_oops:
>   *	Dump oops and panic log or only panic.
>   * @read, @write:
> @@ -33,7 +36,9 @@
>   *	the relative size of the space provided, not the whole disk/flash.
>   *
>   *	On success, the number of bytes read/write should be returned.
> - *	On error, negative number should be returned.
> + *	On error, negative number should be returned. The following returning
> + *	number means more:
> + *	  -EBUSY: pstore/blk should try again later.
>   * @panic_write:
>   *	The write operation only used for panic. It's optional if you do not
>   *	care panic record. If panic occur but blkzone do not recover yet, the
> @@ -54,6 +59,7 @@ struct blkz_info {
>  	unsigned long total_size;
>  	unsigned long dmesg_size;
>  	unsigned long pmsg_size;
> +	unsigned long console_size;
>  	int dump_oops;
>  	blkz_read_op read;
>  	blkz_write_op write;
> -- 
> 1.9.1
> 

-- 
Kees Cook

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