pstore/zone,blk: Add console frontend support

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@allwinnertech.com>
Link: https://lore.kernel.org/lkml/20200511233229.27745-5-keescook@chromium.org/
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index ef01c48..126aa6c 100644 (file)
--- 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 a9e7078..082f6cd 100644 (file)
--- 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 2f8e3b3..ee0b64d 100644 (file)
--- 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;
@@ -545,6 +570,10 @@ static inline int psz_recovery(struct psz_context *cxt)
                goto out;
 
        ret = psz_recover_zone(cxt, cxt->ppsz);
+       if (ret)
+               goto out;
+
+       ret = psz_recover_zone(cxt, cxt->cpsz);
 
 out:
        if (unlikely(ret))
@@ -562,6 +591,7 @@ 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;
 }
 
@@ -626,8 +656,9 @@ 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;
        }
 }
 
@@ -690,9 +721,10 @@ 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 */
@@ -756,9 +788,18 @@ 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:
@@ -783,6 +824,13 @@ 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;
 }
 
@@ -893,6 +941,8 @@ next_zone:
                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;
@@ -953,6 +1003,8 @@ 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,
@@ -1054,6 +1106,15 @@ 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);
@@ -1088,7 +1149,7 @@ 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;
        }
@@ -1111,6 +1172,7 @@ 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
 
@@ -1137,6 +1199,7 @@ 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) {
@@ -1170,6 +1233,10 @@ 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);
@@ -1211,6 +1278,10 @@ 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 29c367a..904ee67 100644 (file)
--- 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;