On Wed, 24 Sept 2025 at 13:51, Jinchao Wang <[email protected]> wrote: > > Provide the /proc/kstackwatch 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.
Why is this in /proc and not debugfs? > ksw_get_config() exposes the configuration pointer as const. > > Signed-off-by: Jinchao Wang <[email protected]> > --- > mm/kstackwatch/kernel.c | 77 +++++++++++++++++++++++++++++++++++- > mm/kstackwatch/kstackwatch.h | 3 ++ > 2 files changed, 79 insertions(+), 1 deletion(-) > > diff --git a/mm/kstackwatch/kernel.c b/mm/kstackwatch/kernel.c > index 3b7009033dd4..4a06ddadd9c7 100644 > --- a/mm/kstackwatch/kernel.c > +++ b/mm/kstackwatch/kernel.c > @@ -3,11 +3,15 @@ > > #include <linux/kstrtox.h> > #include <linux/module.h> > +#include <linux/proc_fs.h> > +#include <linux/seq_file.h> > #include <linux/string.h> > +#include <linux/uaccess.h> > > #include "kstackwatch.h" > > static struct ksw_config *ksw_config; > +static atomic_t config_file_busy = ATOMIC_INIT(0); > > struct param_map { > const char *name; /* long name */ > @@ -74,7 +78,7 @@ 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; > @@ -109,18 +113,89 @@ static int __maybe_unused ksw_parse_config(char *buf, > struct ksw_config *config) > return 0; > } > > +static ssize_t kstackwatch_proc_write(struct file *file, > + const char __user *buffer, size_t count, > + loff_t *pos) > +{ > + 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 kstackwatch_proc_show(struct seq_file *m, void *v) > +{ > + seq_printf(m, "%s\n", ksw_config->user_input); > + return 0; > +} > + > +static int kstackwatch_proc_open(struct inode *inode, struct file *file) > +{ > + if (atomic_cmpxchg(&config_file_busy, 0, 1)) > + return -EBUSY; > + > + return single_open(file, kstackwatch_proc_show, NULL); > +} > + > +static int kstackwatch_proc_release(struct inode *inode, struct file *file) > +{ > + atomic_set(&config_file_busy, 0); > + return single_release(inode, file); > +} > + > +static const struct proc_ops kstackwatch_proc_ops = { > + .proc_open = kstackwatch_proc_open, > + .proc_read = seq_read, > + .proc_write = kstackwatch_proc_write, > + .proc_lseek = seq_lseek, > + .proc_release = kstackwatch_proc_release, > +}; > + > +const struct ksw_config *ksw_get_config(void) > +{ > + return ksw_config; > +} > static int __init kstackwatch_init(void) > { > ksw_config = kzalloc(sizeof(*ksw_config), GFP_KERNEL); > if (!ksw_config) > return -ENOMEM; > > + if (!proc_create("kstackwatch", 0600, NULL, &kstackwatch_proc_ops)) { > + pr_err("create proc kstackwatch fail"); > + kfree(ksw_config); > + return -ENOMEM; > + } > + > pr_info("module loaded\n"); > return 0; > } > > static void __exit kstackwatch_exit(void) > { > + remove_proc_entry("kstackwatch", NULL); > + 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 > > -- > You received this message because you are subscribed to the Google Groups > "kasan-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/kasan-dev/20250924115124.194940-7-wangjinchao600%40gmail.com.
