[PATCH v6 12/18] pstore/zone,blk: Add ftrace frontend support

From: Kees Cook
Date: Sat May 09 2020 - 19:41:58 EST

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From: WeiXiong Liao <liaoweixiong@xxxxxxxxxxxxxxxxx>

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

Signed-off-by: WeiXiong Liao <liaoweixiong@xxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/1585126506-18635-7-git-send-email-liaoweixiong@xxxxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
fs/pstore/Kconfig | 12 ++++
fs/pstore/blk.c | 9 +++
fs/pstore/zone.c | 113 +++++++++++++++++++++++++++++++++++-
include/linux/pstore_zone.h | 2 +
4 files changed, 135 insertions(+), 1 deletion(-)

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index f1484f751c5e..16a0440d8d5a 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -248,3 +248,15 @@ config PSTORE_BLK_CONSOLE_SIZE

NOTE that, both Kconfig and module parameters can configure
pstore/blk, but module parameters have priority over Kconfig.
+
+config PSTORE_BLK_FTRACE_SIZE
+ int "Size in Kbytes of ftarce to store"
+ depends on PSTORE_BLK
+ depends on PSTORE_FTRACE
+ default 64
+ help
+ This just sets size of ftrace (ftrace_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 317e7ea9e2de..04930b971c22 100644
--- a/fs/pstore/blk.c
+++ b/fs/pstore/blk.c
@@ -43,6 +43,14 @@ static long console_size = -1;
module_param(console_size, long, 0400);
MODULE_PARM_DESC(console_size, "console size in kbytes");

+#if IS_ENABLED(CONFIG_PSTORE_FTRACE)
+static long ftrace_size = CONFIG_PSTORE_BLK_FTRACE_SIZE;
+#else
+static long ftrace_size = -1;
+#endif
+module_param(ftrace_size, long, 0400);
+MODULE_PARM_DESC(ftrace_size, "ftrace size in kbytes");
+
/*
* blkdev - the block device to use for pstore storage
*
@@ -151,6 +159,7 @@ 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);
+ verify_size(ftrace_size, 4096, dev->flags & PSTORE_FLAGS_FTRACE);
#undef verify_size

pstore_zone_info->total_size = dev->total_size;
diff --git a/fs/pstore/zone.c b/fs/pstore/zone.c
index f3bd6a7dc06d..45c0a422f1de 100644
--- a/fs/pstore/zone.c
+++ b/fs/pstore/zone.c
@@ -92,11 +92,14 @@ struct pstore_zone {
* @opszs: oops/panic storage zones
* @ppsz: pmsg storage zone
* @cpsz: console storage zone
+ * @fpszs: ftrace storage zones
* @kmsg_max_cnt: max count of @opszs
* @kmsg_read_cnt: counter to read oops zone
* @kmsg_write_cnt: counter to write
* @pmsg_read_cnt: counter to read pmsg zone
* @console_read_cnt: counter to read console zone
+ * @ftrace_max_cnt: max count of @fpszs
+ * @ftrace_read_cnt: counter to read ftrace zone
* @oops_counter: counter to oops
* @panic_counter: counter to panic
* @recovered: whether finish recovering data from storage
@@ -109,11 +112,14 @@ struct psz_context {
struct pstore_zone **opszs;
struct pstore_zone *ppsz;
struct pstore_zone *cpsz;
+ struct pstore_zone **fpszs;
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;
+ unsigned int ftrace_max_cnt;
+ unsigned int ftrace_read_cnt;
/*
* the counter should be recovered when recover.
* It records the oops/panic times after burning rather than booting.
@@ -314,6 +320,8 @@ static void psz_flush_all_dirty_zones(struct work_struct *work)
ret |= psz_flush_dirty_zone(cxt->cpsz);
if (cxt->opszs)
ret |= psz_flush_dirty_zones(cxt->opszs, cxt->kmsg_max_cnt);
+ if (cxt->fpszs)
+ ret |= psz_flush_dirty_zones(cxt->fpszs, cxt->ftrace_max_cnt);
if (ret && cxt->pstore_zone_info)
schedule_delayed_work(&psz_cleaner, msecs_to_jiffies(1000));
}
@@ -550,6 +558,31 @@ static int psz_recover_zone(struct psz_context *cxt, struct pstore_zone *zone)
return ret;
}

+static int psz_recover_zones(struct psz_context *cxt,
+ struct pstore_zone **zones, unsigned int cnt)
+{
+ int ret;
+ unsigned int i;
+ struct pstore_zone *zone;
+
+ if (!zones)
+ return 0;
+
+ for (i = 0; i < cnt; i++) {
+ zone = zones[i];
+ if (unlikely(!zone))
+ continue;
+ ret = psz_recover_zone(cxt, zone);
+ if (ret)
+ goto recover_fail;
+ }
+
+ return 0;
+recover_fail:
+ pr_debug("recover %s[%u] failed\n", zone->name, i);
+ return ret;
+}
+
/**
* psz_recovery() - recover data from storage
* @cxt: the context of pstore/zone
@@ -577,6 +610,10 @@ static inline int psz_recovery(struct psz_context *cxt)
if (ret)
goto recover_fail;

+ ret = psz_recover_zones(cxt, cxt->fpszs, cxt->ftrace_max_cnt);
+ if (ret)
+ goto recover_fail;
+
pr_debug("recover end!\n");
atomic_set(&cxt->recovered, 1);
return 0;
@@ -593,6 +630,7 @@ static int psz_pstore_open(struct pstore_info *psi)
cxt->kmsg_read_cnt = 0;
cxt->pmsg_read_cnt = 0;
cxt->console_read_cnt = 0;
+ cxt->ftrace_read_cnt = 0;
return 0;
}

@@ -659,6 +697,10 @@ static int psz_pstore_erase(struct pstore_record *record)
return psz_record_erase(cxt, cxt->ppsz);
case PSTORE_TYPE_CONSOLE:
return psz_record_erase(cxt, cxt->cpsz);
+ case PSTORE_TYPE_FTRACE:
+ if (record->id >= cxt->ftrace_max_cnt)
+ return -EINVAL;
+ return psz_record_erase(cxt, cxt->fpszs[record->id]);
default: return -EINVAL;
}
}
@@ -801,6 +843,13 @@ static int notrace psz_pstore_write(struct pstore_record *record)
return psz_record_write(cxt->cpsz, record);
case PSTORE_TYPE_PMSG:
return psz_record_write(cxt->ppsz, record);
+ case PSTORE_TYPE_FTRACE: {
+ int zonenum = smp_processor_id();
+
+ if (!cxt->fpszs)
+ return -ENOSPC;
+ return psz_record_write(cxt->fpszs[zonenum], record);
+ }
default:
return -EINVAL;
}
@@ -816,6 +865,14 @@ static struct pstore_zone *psz_read_next_zone(struct psz_context *cxt)
return zone;
}

+ if (cxt->ftrace_read_cnt < cxt->ftrace_max_cnt)
+ /*
+ * No need psz_old_ok(). Let psz_ftrace_read() do so for
+ * combination. psz_ftrace_read() should traverse over
+ * all zones in case of some zone without data.
+ */
+ return cxt->fpszs[cxt->ftrace_read_cnt++];
+
if (cxt->pmsg_read_cnt == 0) {
cxt->pmsg_read_cnt++;
zone = cxt->ppsz;
@@ -890,6 +947,37 @@ static ssize_t psz_kmsg_read(struct pstore_zone *zone,
return size + hlen;
}

+/* try to combine all ftrace zones */
+static ssize_t psz_ftrace_read(struct pstore_zone *zone,
+ struct pstore_record *record)
+{
+ struct psz_context *cxt = record->psi->data;
+ struct psz_buffer *buf;
+ int ret;
+
+ if (!zone || !record)
+ return -ENOSPC;
+
+ if (!psz_old_ok(zone))
+ goto out;
+
+ buf = (struct psz_buffer *)zone->oldbuf;
+ if (!buf)
+ return -ENOMSG;
+
+ ret = pstore_ftrace_combine_log(&record->buf, &record->size,
+ (char *)buf->data, atomic_read(&buf->datalen));
+ if (unlikely(ret))
+ return ret;
+
+out:
+ if (cxt->ftrace_read_cnt < cxt->ftrace_max_cnt)
+ /* then, read next ftrace zone */
+ return -ENOMSG;
+ record->id = 0;
+ return record->size ? record->size : -ENOMSG;
+}
+
static ssize_t psz_record_read(struct pstore_zone *zone,
struct pstore_record *record)
{
@@ -940,6 +1028,9 @@ 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_FTRACE:
+ readop = psz_ftrace_read;
+ break;
case PSTORE_TYPE_CONSOLE:
fallthrough;
case PSTORE_TYPE_PMSG:
@@ -1004,6 +1095,8 @@ static void psz_free_all_zones(struct psz_context *cxt)
psz_free_zone(&cxt->ppsz);
if (cxt->cpsz)
psz_free_zone(&cxt->cpsz);
+ if (cxt->fpszs)
+ psz_free_zones(&cxt->fpszs, &cxt->ftrace_max_cnt);
}

static struct pstore_zone *psz_init_zone(enum pstore_type_id type,
@@ -1114,6 +1207,17 @@ static int psz_alloc_zones(struct psz_context *cxt)
goto free_out;
}

+ off_size += info->ftrace_size;
+ cxt->fpszs = psz_init_zones(PSTORE_TYPE_FTRACE, &off,
+ info->ftrace_size,
+ info->ftrace_size / nr_cpu_ids,
+ &cxt->ftrace_max_cnt);
+ if (IS_ERR(cxt->fpszs)) {
+ err = PTR_ERR(cxt->fpszs);
+ cxt->fpszs = NULL;
+ goto free_out;
+ }
+
cxt->opszs = psz_init_zones(PSTORE_TYPE_DMESG, &off,
info->total_size - off_size,
info->kmsg_size, &cxt->kmsg_max_cnt);
@@ -1148,7 +1252,8 @@ int register_pstore_zone(struct pstore_zone_info *info)
return -EINVAL;
}

- if (!info->kmsg_size && !info->pmsg_size && !info->console_size) {
+ if (!info->kmsg_size && !info->pmsg_size && !info->console_size &&
+ !info->ftrace_size) {
pr_warn("at least one record size must be non-zero\n");
return -EINVAL;
}
@@ -1172,6 +1277,7 @@ int register_pstore_zone(struct pstore_zone_info *info)
check_size(kmsg_size, SECTOR_SIZE);
check_size(pmsg_size, SECTOR_SIZE);
check_size(console_size, SECTOR_SIZE);
+ check_size(ftrace_size, SECTOR_SIZE);

#undef check_size

@@ -1199,6 +1305,7 @@ int register_pstore_zone(struct pstore_zone_info *info)
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);
+ pr_debug("\tftrace size : %ld Bytes\n", info->ftrace_size);

err = psz_alloc_zones(cxt);
if (err) {
@@ -1236,6 +1343,10 @@ int register_pstore_zone(struct pstore_zone_info *info)
cxt->pstore.flags |= PSTORE_FLAGS_CONSOLE;
pr_cont(" console");
}
+ if (info->ftrace_size) {
+ cxt->pstore.flags |= PSTORE_FLAGS_FTRACE;
+ pr_cont(" ftrace");
+ }
pr_cont("\n");

err = pstore_register(&cxt->pstore);
diff --git a/include/linux/pstore_zone.h b/include/linux/pstore_zone.h
index da294e6d7661..94f441b8b616 100644
--- a/include/linux/pstore_zone.h
+++ b/include/linux/pstore_zone.h
@@ -19,6 +19,7 @@ typedef ssize_t (*psz_write_op)(const char *, size_t, loff_t);
* @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.
+ * @ftrace_size:The size of ftrace 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
@@ -37,6 +38,7 @@ struct pstore_zone_info {
int max_reason;
unsigned long pmsg_size;
unsigned long console_size;
+ unsigned long ftrace_size;
psz_read_op read;
psz_write_op write;
psz_write_op panic_write;
--
2.20.1

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Next in thread: Kees Cook: "[PATCH v6 09/18] pstore/blk: Introduce backend for block devices"
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