[PATCH v4 06/12] pstore/blk: Add console frontend support

[Kees Cook <keescook@xxxxxxxxxxxx>]

From: WeiXiong Liao <liaoweixiong@xxxxxxxxxxxxxxxxx>

Support backend for console. To enable console backend, just make
console_size be greater than 0 and a multiple of 4096.

Signed-off-by: WeiXiong Liao <liaoweixiong@xxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/1585126506-18635-6-git-send-email-liaoweixiong@xxxxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 fs/pstore/Kconfig           | 12 +++++++
 fs/pstore/blk.c             | 12 ++++++-
 fs/pstore/zone.c            | 67 +++++++++++++++++++++++++++++++++++--
 include/linux/pstore_zone.h |  4 ++-
 4 files changed, 90 insertions(+), 5 deletions(-)

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index f18cd126d83f..f1484f751c5e 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -236,3 +236,15 @@ config PSTORE_BLK_PMSG_SIZE
 
 	  NOTE that, both Kconfig and module parameters can configure
 	  pstore/blk, but module parameters have priority over Kconfig.
+
+config PSTORE_BLK_CONSOLE_SIZE
+	int "Size in Kbytes of console to store"
+	depends on PSTORE_BLK
+	depends on PSTORE_CONSOLE
+	default 64
+	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
+	  pstore/blk, but module parameters have priority over Kconfig.
diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c
index 401e5ba66a5f..813025ea7edd 100644
--- a/fs/pstore/blk.c
+++ b/fs/pstore/blk.c
@@ -32,6 +32,14 @@ static long pmsg_size = -1;
 module_param(pmsg_size, long, 0400);
 MODULE_PARM_DESC(pmsg_size, "pmsg size in kbytes");
 
+#if IS_ENABLED(CONFIG_PSTORE_CONSOLE)
+static long console_size = CONFIG_PSTORE_BLK_CONSOLE_SIZE;
+#else
+static long console_size = -1;
+#endif
+module_param(console_size, long, 0400);
+MODULE_PARM_DESC(console_size, "console size in kbytes");
+
 /*
  * blkdev - The block device to use.
  *
@@ -83,7 +91,8 @@ static struct bdev_info {
  *		whole disk).
  *		On success, the number of bytes should be returned, others
  *		means error.
- * @write:	The same as @read.
+ * @write:	The same as @read, but the following error number:
+ *		-EBUSY means try to write again later.
  * @panic_write:The write operation only used for panic case. It's optional
  *		if you do not care panic log. The parameters and return value
  *		are the same as @read.
@@ -133,6 +142,7 @@ static int psblk_register_do(struct psblk_device *dev)
 
 	verify_size(kmsg_size, 4096, dev->flags & PSTORE_FLAGS_DMESG);
 	verify_size(pmsg_size, 4096, dev->flags & PSTORE_FLAGS_PMSG);
+	verify_size(console_size, 4096, dev->flags & PSTORE_FLAGS_CONSOLE);
 #undef verify_size
 
 	pstore_zone_info->total_size = dev->total_size;
diff --git a/fs/pstore/zone.c b/fs/pstore/zone.c
index f472b06a6c14..0b952eea39fe 100644
--- a/fs/pstore/zone.c
+++ b/fs/pstore/zone.c
@@ -87,10 +87,12 @@ struct pstore_zone {
  *
  * @opszs: oops/panic storage zones
  * @ppsz: pmsg storage zone
+ * @cpsz: console storage zone
  * @oops_max_cnt: max count of @opszs
  * @oops_read_cnt: counter to read oops zone
  * @oops_write_cnt: counter to write
  * @pmsg_read_cnt: counter to read pmsg zone
+ * @console_read_cnt: counter to read console zone
  * @oops_counter: counter to oops
  * @panic_counter: counter to panic
  * @recovered: whether finish recovering data from storage
@@ -102,10 +104,12 @@ struct pstore_zone {
 struct psz_context {
 	struct pstore_zone **opszs;
 	struct pstore_zone *ppsz;
+	struct pstore_zone *cpsz;
 	unsigned int oops_max_cnt;
 	unsigned int oops_read_cnt;
 	unsigned int oops_write_cnt;
 	unsigned int pmsg_read_cnt;
+	unsigned int console_read_cnt;
 	/*
 	 * the counter should be recovered when recover.
 	 * It records the oops/panic times after burning rather than booting.
@@ -125,6 +129,9 @@ struct psz_context {
 };
 static struct psz_context psz_cxt;
 
+static void psz_flush_all_dirty_zones(struct work_struct *);
+static DECLARE_WORK(psz_cleaner, psz_flush_all_dirty_zones);
+
 /**
  * enum psz_flush_mode - flush mode for psz_zone_write()
  *
@@ -235,6 +242,9 @@ static int psz_zone_write(struct pstore_zone *zone,
 	return 0;
 dirty:
 	atomic_set(&zone->dirty, true);
+	/* flush dirty zones nicely */
+	if (wcnt == -EBUSY && !is_on_panic())
+		schedule_work(&psz_cleaner);
 	return -EBUSY;
 }
 
@@ -291,6 +301,15 @@ static int psz_move_zone(struct pstore_zone *old, struct pstore_zone *new)
 	return 0;
 }
 
+static void psz_flush_all_dirty_zones(struct work_struct *work)
+{
+	struct psz_context *cxt = &psz_cxt;
+
+	psz_flush_dirty_zone(cxt->ppsz);
+	psz_flush_dirty_zone(cxt->cpsz);
+	psz_flush_dirty_zones(cxt->opszs, cxt->oops_max_cnt);
+}
+
 static int psz_recover_oops_data(struct psz_context *cxt)
 {
 	struct pstore_zone_info *info = cxt->pstore_zone_info;
@@ -546,6 +565,10 @@ static inline int psz_recovery(struct psz_context *cxt)
 	if (ret)
 		goto recover_fail;
 
+	ret = psz_recover_zone(cxt, cxt->cpsz);
+	if (ret)
+		goto recover_fail;
+
 	pr_debug("recover end!\n");
 	atomic_set(&cxt->recovered, 1);
 	return 0;
@@ -561,6 +584,7 @@ static int psz_pstore_open(struct pstore_info *psi)
 
 	cxt->oops_read_cnt = 0;
 	cxt->pmsg_read_cnt = 0;
+	cxt->console_read_cnt = 0;
 	return 0;
 }
 
@@ -625,8 +649,9 @@ static int psz_pstore_erase(struct pstore_record *record)
 		return psz_oops_erase(cxt, cxt->opszs[record->id], record);
 	case PSTORE_TYPE_PMSG:
 		return psz_record_erase(cxt, cxt->ppsz);
-	default:
-		return -EINVAL;
+	case PSTORE_TYPE_CONSOLE:
+		return psz_record_erase(cxt, cxt->cpsz);
+	default: return -EINVAL;
 	}
 }
 
@@ -753,9 +778,18 @@ static int notrace psz_pstore_write(struct pstore_record *record)
 			record->reason == KMSG_DUMP_PANIC)
 		atomic_set(&cxt->on_panic, 1);
 
+	/*
+	 * if on panic, do not write except panic records
+	 * Fix case that panic_write prints log which wakes up console backend.
+	 */
+	if (is_on_panic() && record->type != PSTORE_TYPE_DMESG)
+		return -EBUSY;
+
 	switch (record->type) {
 	case PSTORE_TYPE_DMESG:
 		return psz_oops_write(cxt, record);
+	case PSTORE_TYPE_CONSOLE:
+		return psz_record_write(cxt->cpsz, record);
 	case PSTORE_TYPE_PMSG:
 		return psz_record_write(cxt->ppsz, record);
 	default:
@@ -780,6 +814,13 @@ static struct pstore_zone *psz_read_next_zone(struct psz_context *cxt)
 			return zone;
 	}
 
+	if (cxt->console_read_cnt == 0) {
+		cxt->console_read_cnt++;
+		zone = cxt->cpsz;
+		if (psz_old_ok(zone))
+			return zone;
+	}
+
 	return NULL;
 }
 
@@ -890,6 +931,8 @@ static ssize_t psz_pstore_read(struct pstore_record *record)
 		readop = psz_oops_read;
 		record->id = cxt->oops_read_cnt - 1;
 		break;
+	case PSTORE_TYPE_CONSOLE:
+		fallthrough;
 	case PSTORE_TYPE_PMSG:
 		readop = psz_record_read;
 		break;
@@ -1037,6 +1080,8 @@ static void psz_free_all_zones(struct psz_context *cxt)
 		psz_free_zones(&cxt->opszs, &cxt->oops_max_cnt);
 	if (cxt->ppsz)
 		psz_free_zone(&cxt->ppsz);
+	if (cxt->cpsz)
+		psz_free_zone(&cxt->cpsz);
 }
 
 static int psz_alloc_zones(struct psz_context *cxt)
@@ -1053,6 +1098,14 @@ static int psz_alloc_zones(struct psz_context *cxt)
 		goto free_out;
 	}
 
+	off_size += info->console_size;
+	cxt->cpsz = psz_init_zone(PSTORE_TYPE_CONSOLE, &off,
+			info->console_size);
+	if (IS_ERR(cxt->cpsz)) {
+		err = PTR_ERR(cxt->cpsz);
+		goto free_out;
+	}
+
 	cxt->opszs = psz_init_zones(PSTORE_TYPE_DMESG, &off,
 			info->total_size - off_size,
 			info->kmsg_size, &cxt->oops_max_cnt);
@@ -1086,7 +1139,7 @@ int register_pstore_zone(struct pstore_zone_info *info)
 		return -EINVAL;
 	}
 
-	if (!info->kmsg_size && !info->pmsg_size) {
+	if (!info->kmsg_size && !info->pmsg_size && !info->console_size) {
 		pr_warn("at least one of the records be non-zero\n");
 		return -EINVAL;
 	}
@@ -1114,6 +1167,7 @@ int register_pstore_zone(struct pstore_zone_info *info)
 	check_size(total_size, 4096);
 	check_size(kmsg_size, SECTOR_SIZE);
 	check_size(pmsg_size, SECTOR_SIZE);
+	check_size(console_size, SECTOR_SIZE);
 
 #undef check_size
 
@@ -1141,6 +1195,7 @@ int register_pstore_zone(struct pstore_zone_info *info)
 	pr_debug("\ttotal size : %ld Bytes\n", info->total_size);
 	pr_debug("\toops size : %ld Bytes\n", info->kmsg_size);
 	pr_debug("\tpmsg size : %ld Bytes\n", info->pmsg_size);
+	pr_debug("\tconsole size : %ld Bytes\n", info->console_size);
 
 	err = psz_alloc_zones(cxt);
 	if (err) {
@@ -1173,6 +1228,10 @@ int register_pstore_zone(struct pstore_zone_info *info)
 		cxt->pstore.flags |= PSTORE_FLAGS_PMSG;
 		pr_cont(" pmsg");
 	}
+	if (info->console_size) {
+		cxt->pstore.flags |= PSTORE_FLAGS_CONSOLE;
+		pr_cont(" console");
+	}
 	pr_cont("\n");
 
 	err = pstore_register(&cxt->pstore);
@@ -1204,6 +1263,8 @@ void unregister_pstore_zone(struct pstore_zone_info *info)
 {
 	struct psz_context *cxt = &psz_cxt;
 
+	flush_work(&psz_cleaner);
+
 	pstore_unregister(&cxt->pstore);
 	kfree(cxt->pstore.buf);
 	cxt->pstore.bufsize = 0;
diff --git a/include/linux/pstore_zone.h b/include/linux/pstore_zone.h
index 39c2cb944123..da294e6d7661 100644
--- a/include/linux/pstore_zone.h
+++ b/include/linux/pstore_zone.h
@@ -18,11 +18,12 @@ typedef ssize_t (*psz_write_op)(const char *, size_t, loff_t);
  *		it must be multiple of SECTOR_SIZE(512 Bytes).
  * @max_reason: Maximum kmsg dump reason to store.
  * @pmsg_size:	The size of pmsg zone which is the same as @kmsg_size.
+ * @console_size:The size of console zone which is the same as @kmsg_size.
  * @read:	The general read operation. Both of the function parameters
  *		@size and @offset are relative value to storage.
  *		On success, the number of bytes should be returned, others
  *		means error.
- * @write:	The same as @read.
+ * @write:	The same as @read, but -EBUSY means try to write again later.
  * @panic_write:The write operation only used for panic case. It's optional
  *		if you do not care panic log. The parameters and return value
  *		are the same as @read.
@@ -35,6 +36,7 @@ struct pstore_zone_info {
 	unsigned long kmsg_size;
 	int max_reason;
 	unsigned long pmsg_size;
+	unsigned long console_size;
 	psz_read_op read;
 	psz_write_op write;
 	psz_write_op panic_write;
-- 
2.20.1


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