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Date: Mon, 6 Feb 2023 14:18:13 +0800
From: Victor Hassan <victor@...winnertech.com>
To: keescook@...omium.org
Cc: tony.luck@...el.com, gpiccoli@...lia.com,
linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] pstore/blk: Export a method to implemente panic_write()
The panic_write() is necessary to write the pstore frontend message
to blk devices when panic. Here is a way to register panic_write when
we use "best_effort" way to register the pstore blk-backend.
Usage:
xx_register_pstore_panic_write(pstore_blk_notifier_type type,
struct pstore_device_info *pdi)
{
switch (type) {
case PSTORE_BLK_BACKEND_REGISTER:
case PSTORE_BLK_BACKEND_PANIC_DRV_REGISTER:
...
pid->zone.panic_write = xxx;
...
break;
case PSTORE_BLK_BACKEND_UNREGISTER:
case PSTORE_BLK_BACKEND_PANIC_DRV_UNREGISTER:
...
pdi->zone.panic_write = NULL;
...
break;
default:
break;
}
}
static struct pstore_blk_notifier pbn = {
.notitifer_call = xx_register_pstore_panic_write;
}
use {un,}register_pstore_blk_panic_notifier() to register/unregister
pstore_blk_notifier
Signed-off-by: Victor Hassan <victor@...winnertech.com>
---
fs/pstore/blk.c | 101 +++++++++++++++++++++++++++++++++++--
include/linux/pstore_blk.h | 19 +++++++
2 files changed, 116 insertions(+), 4 deletions(-)
diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c
index 4ae0cfcd15f2..2c70a3bff1ae 100644
--- a/fs/pstore/blk.c
+++ b/fs/pstore/blk.c
@@ -18,6 +18,7 @@
#include <linux/file.h>
#include <linux/init_syscalls.h>
#include <linux/mount.h>
+#include <linux/notifier.h>
static long kmsg_size = CONFIG_PSTORE_BLK_KMSG_SIZE;
module_param(kmsg_size, long, 0400);
@@ -72,6 +73,14 @@ static DEFINE_MUTEX(pstore_blk_lock);
static struct file *psblk_file;
static struct pstore_device_info *pstore_device_info;
+static struct {
+ struct raw_notifier_head chain;
+ struct pstore_blk_notifier *pbn;
+ bool notifier;
+} pstore_blk_panic_notifier = {
+ .chain = RAW_NOTIFIER_INIT(pstore_blk_panic_notifier.chain),
+};
+
#define check_size(name, alignsize) ({ \
long _##name_ = (name); \
_##name_ = _##name_ <= 0 ? 0 : (_##name_ * 1024); \
@@ -94,6 +103,82 @@ static struct pstore_device_info *pstore_device_info;
dev->zone.name = _##name_; \
}
+static int pstore_blk_panic_notifier_call(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ int ret = 0;
+ struct pstore_blk_notifier *pbn =
+ container_of(nb, struct pstore_blk_notifier, nb);
+
+ if (pbn)
+ ret = pbn->notifier_call(action, data);
+
+ return ret;
+}
+
+int register_pstore_blk_panic_notifier(struct pstore_blk_notifier *pbn)
+{
+ int err = 0;
+ struct notifier_block *nb;
+
+ mutex_lock(&pstore_blk_lock);
+
+ if (pstore_blk_panic_notifier.notifier) {
+ pr_info("had register panic\n");
+ goto unlock;
+ }
+
+ nb = &pbn->nb;
+ nb->notifier_call = pstore_blk_panic_notifier_call;
+
+ err = raw_notifier_chain_register(&pstore_blk_panic_notifier.chain, nb);
+ if (err)
+ goto unlock;
+
+ if (pstore_device_info)
+ err = nb->notifier_call(nb, PSTORE_BLK_BACKEND_PANIC_DRV_REGISTER,
+ pstore_device_info);
+
+ if (!err)
+ pstore_blk_panic_notifier.notifier = true;
+
+unlock:
+ mutex_unlock(&pstore_blk_lock);
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(register_pstore_blk_panic_notifier);
+
+void unregister_pstore_blk_panic_notifier(struct pstore_blk_notifier *pbn)
+{
+ struct notifier_block *nb = &pbn->nb;
+
+ mutex_lock(&pstore_blk_lock);
+
+ raw_notifier_chain_unregister(&pstore_blk_panic_notifier.chain, nb);
+
+ if (pstore_device_info)
+ nb->notifier_call(nb, PSTORE_BLK_BACKEND_PANIC_DRV_UNREGISTER,
+ pstore_device_info);
+
+ pstore_blk_panic_notifier.notifier = false;
+
+ mutex_unlock(&pstore_blk_lock);
+}
+EXPORT_SYMBOL_GPL(unregister_pstore_blk_panic_notifier);
+
+static int pstore_blk_panic_notifier_init_call(struct pstore_device_info *pdi)
+{
+ return raw_notifier_call_chain(&pstore_blk_panic_notifier.chain,
+ PSTORE_BLK_BACKEND_REGISTER, pdi);
+}
+
+static int pstore_blk_panic_notifier_exit_call(struct pstore_device_info *pdi)
+{
+ return raw_notifier_call_chain(&pstore_blk_panic_notifier.chain,
+ PSTORE_BLK_BACKEND_UNREGISTER, pdi);
+}
+
static int __register_pstore_device(struct pstore_device_info *dev)
{
int ret;
@@ -301,16 +386,22 @@ static int __init __best_effort_init(void)
if (!best_effort_dev)
return -ENOMEM;
+ strcpy(best_effort_dev->path, blkdev);
best_effort_dev->zone.read = psblk_generic_blk_read;
best_effort_dev->zone.write = psblk_generic_blk_write;
ret = __register_pstore_blk(best_effort_dev,
early_boot_devpath(blkdev));
- if (ret)
+ if (ret) {
kfree(best_effort_dev);
- else
- pr_info("attached %s (%lu) (no dedicated panic_write!)\n",
- blkdev, best_effort_dev->zone.total_size);
+ } else {
+ if (pstore_blk_panic_notifier_init_call(best_effort_dev) == NOTIFY_OK)
+ pr_info("attached %s (%lu) (dedicated panic_write!)\n",
+ blkdev, best_effort_dev->zone.total_size);
+ else
+ pr_info("attached %s (%lu) (no dedicated panic_write!)\n",
+ blkdev, best_effort_dev->zone.total_size);
+ }
return ret;
}
@@ -326,6 +417,8 @@ static void __exit __best_effort_exit(void)
if (psblk_file) {
struct pstore_device_info *dev = pstore_device_info;
+ pstore_blk_panic_notifier_exit_call(dev);
+
__unregister_pstore_device(dev);
kfree(dev);
fput(psblk_file);
diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
index 924ca07aafbd..fd2eb927c2c5 100644
--- a/include/linux/pstore_blk.h
+++ b/include/linux/pstore_blk.h
@@ -17,13 +17,32 @@
*
*/
struct pstore_device_info {
+ char path[80];
unsigned int flags;
struct pstore_zone_info zone;
};
+enum pstore_blk_notifier_type {
+ PSTORE_BLK_BACKEND_REGISTER = 1,
+ PSTORE_BLK_BACKEND_PANIC_DRV_REGISTER,
+ PSTORE_BLK_BACKEND_UNREGISTER,
+ PSTORE_BLK_BACKEND_PANIC_DRV_UNREGISTER,
+};
+
+typedef int (*pstore_blk_notifier_fn_t)(enum pstore_blk_notifier_type type,
+ struct pstore_device_info *dev);
+
+struct pstore_blk_notifier {
+ struct notifier_block nb;
+ pstore_blk_notifier_fn_t notifier_call;
+};
+
int register_pstore_device(struct pstore_device_info *dev);
void unregister_pstore_device(struct pstore_device_info *dev);
+int register_pstore_blk_panic_notifier(struct pstore_blk_notifier *pbn);
+void unregister_pstore_blk_panic_notifier(struct pstore_blk_notifier *nb);
+
/**
* struct pstore_blk_config - the pstore_blk backend configuration
*
--
2.29.0
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