[PATCH 2/2] fs:regfs: add panic notifier callback for saving regs

From: Zou Cao
Date: Tue Oct 20 2020 - 02:30:22 EST


register panic notifier callback for saveing regs, add a module
param regfs_panic to enable the show reg info when panic.

Signed-off-by: Zou Cao <zoucao@xxxxxxxxxxxxxxxxx>
---
fs/regfs/inode.c | 39 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/fs/regfs/inode.c b/fs/regfs/inode.c
index 1643fcd..6c79f73 100644
--- a/fs/regfs/inode.c
+++ b/fs/regfs/inode.c
@@ -46,10 +46,41 @@
static LIST_HEAD(regfs_head);

static const struct inode_operations regfs_dir_inode_operations;
-int regfs_debug;
+int regfs_debug = 1;
module_param(regfs_debug, int, S_IRUGO);
MODULE_PARM_DESC(regfs_debug, "enable regfs debug mode");

+static int regfs_panic = 1;
+module_param(regfs_panic, int, S_IRUGO);
+MODULE_PARM_DESC(regfs_debug, "printk the register when panic");
+
+//save all register val when panic
+static int regfs_panic_event(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ struct regfs_fs_info *fsi;
+ struct inode *inode, *next;
+
+
+ list_for_each_entry(fsi, &regfs_head, regfs_head) {
+ list_for_each_entry_safe(inode, next, &fsi->sb->s_inodes, i_sb_list) {
+ struct regfs_inode_info *info = REGFS_I(inode);;
+ //save the regs val
+ if (info->type == RES_TYPE_ITEM) {
+ info->val = readl_relaxed(info->base + info->offset);
+ if (regfs_panic)
+ printk("%llx:%llx\n", (u64)(info->base + info->offset), info->val);
+ }
+ }
+ }
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block regfs_panic_event_nb = {
+ .notifier_call = regfs_panic_event,
+};
+
struct inode *regfs_get_inode(struct super_block *sb, const struct inode *dir, umode_t mode, dev_t dev)
{
struct inode *inode = new_inode(sb);
@@ -328,6 +359,7 @@ static void init_once(void *foo)

static int __init init_regfs_fs(void)
{
+ int ret;

regfs_inode_cachep = kmem_cache_create_usercopy("regfs_inode_cache",
sizeof(struct regfs_inode_info), 0,
@@ -337,11 +369,16 @@ static int __init init_regfs_fs(void)
if (!regfs_inode_cachep)
return -ENOMEM;

+ ret = atomic_notifier_chain_register(&panic_notifier_list, &regfs_panic_event_nb);
+ if (ret)
+ pr_warn("regfs regiter panic notifier failed\n");
+
return register_filesystem(&regfs_fs_type);
}

static void __exit exit_regfs_fs(void)
{
+ atomic_notifier_chain_unregister(&panic_notifier_list, &regfs_panic_event_nb);
unregister_filesystem(&regfs_fs_type);
rcu_barrier();
kmem_cache_destroy(regfs_inode_cachep);
--
1.8.3.1