From 0d4cbc5e83baccd73ebcb0ac975980d66347d5a8 Mon Sep 17 00:00:00 2001 From: Bradley Morgan Date: Wed, 30 Sep 2026 00:09:42 +0900 Subject: [PATCH] kprobes: use DEFINE_DEBUGFS_ATTRIBUTE for the enabled knob This enabled knob is a disgusting terrible hack. It has rolled its own read/write pair since 2007, writing '1' or '0' into a three byte buffer by hand just to print a single character, with an XXX comment begging debugfs for write callbacks on bool files. DEFINE_DEBUGFS_ATTRIBUTE showed up in 2016 and does exactly that, so the disgusting terrible hack has outlived its excuse for nine years. Kill it, and the stale comment with it. The behavior does not change, except the write only accepts 0/1 now instead of y/n/on/off, and nothing uses anything else. Link: https://lore.kernel.org/all/20260818015318.24103-1-include@grrlz.net/ Signed-off-by: Bradley Morgan Signed-off-by: Masami Hiramatsu (Google) --- kernel/kprobes.c | 43 +++++++++---------------------------------- 1 file changed, 9 insertions(+), 34 deletions(-) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 4edd8ca5c657..7b6baa4c6fda 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -3025,47 +3025,22 @@ static int disarm_all_kprobes(void) return ret; } -/* - * XXX: The debugfs bool file interface doesn't allow for callbacks - * when the bool state is switched. We can reuse that facility when - * available - */ -static ssize_t read_enabled_file_bool(struct file *file, - char __user *user_buf, size_t count, loff_t *ppos) +static int kprobes_enabled_set(void *data, u64 val) { - char buf[3]; + if (val) + return arm_all_kprobes(); - if (!kprobes_all_disarmed) - buf[0] = '1'; - else - buf[0] = '0'; - buf[1] = '\n'; - buf[2] = 0x00; - return simple_read_from_buffer(user_buf, count, ppos, buf, 2); + return disarm_all_kprobes(); } -static ssize_t write_enabled_file_bool(struct file *file, - const char __user *user_buf, size_t count, loff_t *ppos) +static int kprobes_enabled_get(void *data, u64 *val) { - bool enable; - int ret; - - ret = kstrtobool_from_user(user_buf, count, &enable); - if (ret) - return ret; - - ret = enable ? arm_all_kprobes() : disarm_all_kprobes(); - if (ret) - return ret; - - return count; + *val = !kprobes_all_disarmed; + return 0; } -static const struct file_operations fops_kp = { - .read = read_enabled_file_bool, - .write = write_enabled_file_bool, - .llseek = default_llseek, -}; +DEFINE_DEBUGFS_ATTRIBUTE(fops_kp, kprobes_enabled_get, + kprobes_enabled_set, "%llu\n"); static int __init debugfs_kprobe_init(void) {