Provide the debugfs config file to read or update the configuration. Only a single process can open this file at a time, enforced using atomic config_file_busy, to prevent concurrent access.
ksw_get_config() exposes the configuration pointer as const. Signed-off-by: Jinchao Wang <[email protected]> --- mm/kstackwatch/kernel.c | 104 +++++++++++++++++++++++++++++++++-- mm/kstackwatch/kstackwatch.h | 3 + 2 files changed, 103 insertions(+), 4 deletions(-) diff --git a/mm/kstackwatch/kernel.c b/mm/kstackwatch/kernel.c index 3b7009033dd4..898ebb2966fe 100644 --- a/mm/kstackwatch/kernel.c +++ b/mm/kstackwatch/kernel.c @@ -1,13 +1,18 @@ // SPDX-License-Identifier: GPL-2.0 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/debugfs.h> #include <linux/kstrtox.h> #include <linux/module.h> #include <linux/string.h> +#include <linux/uaccess.h> #include "kstackwatch.h" +static atomic_t dbgfs_config_busy = ATOMIC_INIT(0); static struct ksw_config *ksw_config; +static struct dentry *dbgfs_config; +static struct dentry *dbgfs_dir; struct param_map { const char *name; /* long name */ @@ -74,7 +79,7 @@ static int ksw_parse_param(struct ksw_config *config, const char *key, * - sp_offset |so (u16) : offset from stack pointer at func_offset * - watch_len |wl (u16) : watch length (1,2,4,8) */ -static int __maybe_unused ksw_parse_config(char *buf, struct ksw_config *config) +static int ksw_parse_config(char *buf, struct ksw_config *config) { char *part, *key, *val; int ret; @@ -109,20 +114,111 @@ static int __maybe_unused ksw_parse_config(char *buf, struct ksw_config *config) return 0; } +static ssize_t ksw_dbgfs_read(struct file *file, char __user *buf, size_t count, + loff_t *ppos) +{ + return simple_read_from_buffer(buf, count, ppos, ksw_config->user_input, + ksw_config->user_input ? strlen(ksw_config->user_input) : 0); +} + +static ssize_t ksw_dbgfs_write(struct file *file, const char __user *buffer, + size_t count, loff_t *ppos) +{ + char input[MAX_CONFIG_STR_LEN]; + int ret; + + if (count == 0 || count >= sizeof(input)) + return -EINVAL; + + if (copy_from_user(input, buffer, count)) + return -EFAULT; + + input[count] = '\0'; + strim(input); + + if (!strlen(input)) { + pr_info("config cleared\n"); + return count; + } + + ret = ksw_parse_config(input, ksw_config); + if (ret) { + pr_err("Failed to parse config %d\n", ret); + return ret; + } + + return count; +} + +static int ksw_dbgfs_open(struct inode *inode, struct file *file) +{ + if (atomic_cmpxchg(&dbgfs_config_busy, 0, 1)) + return -EBUSY; + return 0; +} + +static int ksw_dbgfs_release(struct inode *inode, struct file *file) +{ + atomic_set(&dbgfs_config_busy, 0); + return 0; +} + +static const struct file_operations kstackwatch_fops = { + .owner = THIS_MODULE, + .open = ksw_dbgfs_open, + .read = ksw_dbgfs_read, + .write = ksw_dbgfs_write, + .release = ksw_dbgfs_release, + .llseek = default_llseek, +}; + +const struct ksw_config *ksw_get_config(void) +{ + return ksw_config; +} + static int __init kstackwatch_init(void) { + int ret = 0; + ksw_config = kzalloc(sizeof(*ksw_config), GFP_KERNEL); - if (!ksw_config) - return -ENOMEM; + if (!ksw_config) { + ret = -ENOMEM; + goto err_alloc; + } + + dbgfs_dir = debugfs_create_dir("kstackwatch", NULL); + if (!dbgfs_dir) { + ret = -ENOMEM; + goto err_dir; + } + + dbgfs_config = debugfs_create_file("config", 0600, dbgfs_dir, NULL, + &kstackwatch_fops); + if (!dbgfs_config) { + ret = -ENOMEM; + goto err_file; + } pr_info("module loaded\n"); return 0; + +err_file: + debugfs_remove_recursive(dbgfs_dir); + dbgfs_dir = NULL; +err_dir: + kfree(ksw_config); + ksw_config = NULL; +err_alloc: + return ret; } static void __exit kstackwatch_exit(void) { + debugfs_remove_recursive(dbgfs_dir); + kfree(ksw_config->func_name); + kfree(ksw_config->user_input); kfree(ksw_config); - pr_info("module unloaded\n"); } diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h index a7bad207f863..983125d5cf18 100644 --- a/mm/kstackwatch/kstackwatch.h +++ b/mm/kstackwatch/kstackwatch.h @@ -29,4 +29,7 @@ struct ksw_config { char *user_input; }; +// singleton, only modified in kernel.c +const struct ksw_config *ksw_get_config(void); + #endif /* _KSTACKWATCH_H */ -- 2.43.0
