[PATCH v8 04/11] pstore/zone,blk: Add console frontend support

From: Kees Cook
Date: Mon May 11 2020 - 19:33:24 EST

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 | 18 +++++++--
fs/pstore/blk.c | 12 +++++-
fs/pstore/zone.c | 81 ++++++++++++++++++++++++++++++++++---
include/linux/pstore_zone.h | 4 +-
4 files changed, 105 insertions(+), 10 deletions(-)

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index ef01c48f0ff7..126aa6c3ecf2 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -180,11 +180,11 @@ config PSTORE_BLK_BLKDEV
help
Which block device should be used for pstore/blk.

- It accept the following variants:
+ It accepts the following variants:
1) <hex_major><hex_minor> device number in hexadecimal representation,
with no leading 0x, for example b302.
- 2) /dev/<disk_name> represents the device number of disk
- 3) /dev/<disk_name><decimal> represents the device number
+ 2) /dev/<disk_name> represents the device name of disk
+ 3) /dev/<disk_name><decimal> represents the device name and number
of partition - device number of disk plus the partition number
4) /dev/<disk_name>p<decimal> - same as the above, this form is
used when disk name of partitioned disk ends with a digit.
@@ -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 log to store"
+ depends on PSTORE_BLK
+ depends on PSTORE_CONSOLE
+ default 64
+ help
+ This just sets size of console log (console_size) to store via
+ 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 e3fa29988b0f..0b88c0bcd36c 100644
--- a/fs/pstore/blk.c
+++ b/fs/pstore/blk.c
@@ -35,6 +35,14 @@ 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 for pstore storage
*
@@ -91,7 +99,8 @@ 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.
@@ -142,6 +151,7 @@ static int psblk_register_do(struct pstore_device_info *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 fe6fde96d722..33c99dc5f980 100644
--- a/fs/pstore/zone.c
+++ b/fs/pstore/zone.c
@@ -91,10 +91,12 @@ struct pstore_zone {
*
* @kpszs: kmsg dump storage zones
* @ppsz: pmsg storage zone
+ * @cpsz: console storage zone
* @kmsg_max_cnt: max count of @kpszs
* @kmsg_read_cnt: counter of total read kmsg dumps
* @kmsg_write_cnt: counter of total kmsg dump writes
* @pmsg_read_cnt: counter of total read pmsg zone
+ * @console_read_cnt: counter of total read console zone
* @oops_counter: counter of oops dumps
* @panic_counter: counter of panic dumps
* @recovered: whether finished recovering data from storage
@@ -106,10 +108,12 @@ struct pstore_zone {
struct psz_context {
struct pstore_zone **kpszs;
struct pstore_zone *ppsz;
+ struct pstore_zone *cpsz;
unsigned int kmsg_max_cnt;
unsigned int kmsg_read_cnt;
unsigned int kmsg_write_cnt;
unsigned int pmsg_read_cnt;
+ unsigned int console_read_cnt;
/*
* These counters should be calculated during recovery.
* It records the oops/panic times after crashes rather than boots.
@@ -129,6 +133,9 @@ struct psz_context {
};
static struct psz_context pstore_zone_cxt;

+static void psz_flush_all_dirty_zones(struct work_struct *);
+static DECLARE_DELAYED_WORK(psz_cleaner, psz_flush_all_dirty_zones);
+
/**
* enum psz_flush_mode - flush mode for psz_zone_write()
*
@@ -237,6 +244,9 @@ 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_delayed_work(&psz_cleaner, msecs_to_jiffies(500));
return -EBUSY;
}

@@ -293,6 +303,21 @@ 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 = &pstore_zone_cxt;
+ int ret = 0;
+
+ if (cxt->ppsz)
+ ret |= psz_flush_dirty_zone(cxt->ppsz);
+ if (cxt->cpsz)
+ ret |= psz_flush_dirty_zone(cxt->cpsz);
+ if (cxt->kpszs)
+ ret |= psz_flush_dirty_zones(cxt->kpszs, cxt->kmsg_max_cnt);
+ if (ret && cxt->pstore_zone_info)
+ schedule_delayed_work(&psz_cleaner, msecs_to_jiffies(1000));
+}
+
static int psz_kmsg_recover_data(struct psz_context *cxt)
{
struct pstore_zone_info *info = cxt->pstore_zone_info;
@@ -548,6 +573,10 @@ 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;
@@ -563,6 +592,7 @@ static int psz_pstore_open(struct pstore_info *psi)

cxt->kmsg_read_cnt = 0;
cxt->pmsg_read_cnt = 0;
+ cxt->console_read_cnt = 0;
return 0;
}

@@ -627,8 +657,9 @@ static int psz_pstore_erase(struct pstore_record *record)
return psz_kmsg_erase(cxt, cxt->kpszs[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;
}
}

@@ -691,9 +722,10 @@ static int notrace psz_kmsg_write(struct psz_context *cxt,
return -ENOSPC;

ret = psz_kmsg_write_record(cxt, record);
- if (!ret) {
+ if (!ret && is_on_panic()) {
+ /* ensure all data are flushed to storage when panic */
pr_debug("try to flush other dirty zones\n");
- psz_flush_dirty_zones(cxt->kpszs, cxt->kmsg_max_cnt);
+ psz_flush_all_dirty_zones(NULL);
}

/* always return 0 as we had handled it on buffer */
@@ -755,9 +787,18 @@ 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_kmsg_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:
@@ -782,6 +823,13 @@ 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;
}

@@ -892,6 +940,8 @@ static ssize_t psz_pstore_read(struct pstore_record *record)
readop = psz_kmsg_read;
record->id = cxt->kmsg_read_cnt - 1;
break;
+ case PSTORE_TYPE_CONSOLE:
+ fallthrough;
case PSTORE_TYPE_PMSG:
readop = psz_record_read;
break;
@@ -952,6 +1002,8 @@ static void psz_free_all_zones(struct psz_context *cxt)
psz_free_zones(&cxt->kpszs, &cxt->kmsg_max_cnt);
if (cxt->ppsz)
psz_free_zone(&cxt->ppsz);
+ if (cxt->cpsz)
+ psz_free_zone(&cxt->cpsz);
}

static struct pstore_zone *psz_init_zone(enum pstore_type_id type,
@@ -1053,6 +1105,15 @@ 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);
+ cxt->cpsz = NULL;
+ goto free_out;
+ }
+
cxt->kpszs = psz_init_zones(PSTORE_TYPE_DMESG, &off,
info->total_size - off_size,
info->kmsg_size, &cxt->kmsg_max_cnt);
@@ -1087,7 +1148,7 @@ 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 record size must be non-zero\n");
return -EINVAL;
}
@@ -1110,6 +1171,7 @@ 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

@@ -1136,6 +1198,7 @@ int register_pstore_zone(struct pstore_zone_info *info)
pr_debug("\ttotal size : %ld Bytes\n", info->total_size);
pr_debug("\tkmsg 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) {
@@ -1169,6 +1232,10 @@ 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);
@@ -1210,6 +1277,10 @@ void unregister_pstore_zone(struct pstore_zone_info *info)
/* Stop incoming writes from pstore. */
pstore_unregister(&cxt->pstore);

+ /* Flush any pending writes. */
+ psz_flush_all_dirty_zones(NULL);
+ flush_delayed_work(&psz_cleaner);
+
/* Clean up allocations. */
kfree(cxt->pstore.buf);
cxt->pstore.buf = NULL;
diff --git a/include/linux/pstore_zone.h b/include/linux/pstore_zone.h
index 29c367a3bd80..904ee67f4ba2 100644
--- a/include/linux/pstore_zone.h
+++ b/include/linux/pstore_zone.h
@@ -18,11 +18,12 @@ typedef ssize_t (*pstore_zone_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;
pstore_zone_read_op read;
pstore_zone_write_op write;
pstore_zone_write_op panic_write;
--
2.20.1