Re: [RFC] [PATCH] To list all active probes in the system

[Srinivasa Ds <srinivasa@in.ibm.com>]

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Srinivasa Ds wrote:
> Christoph Hellwig wrote:
>> On Tue, Feb 06, 2007 at 03:25:35PM +0530, Srinivasa Ds wrote:
>>> Hi folks
>>>
>>>         I have developed a patch, that lists all active probes in the
>>> system. I have done this through /proc interface. Currently list is
>>> available under /proc/kprobes/list. Any suggestions for better place and
>>> name??
>> /debug/kprobes/list? :)
>>
> Good Idea, I will update my patch to use debugfs.
Patch that uses debugfs.

Signed-off-by: Srinivasa DS <srinivasa@in.ibm.com>






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 fs/debugfs/inode.c      |    4 ++
 include/linux/kprobes.h |    4 ++
 kernel/kprobes.c        |   92 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 100 insertions(+)

Index: linux-2.6.20/fs/debugfs/inode.c
===================================================================
--- linux-2.6.20.orig/fs/debugfs/inode.c
+++ linux-2.6.20/fs/debugfs/inode.c
@@ -25,6 +25,7 @@
 #include <linux/namei.h>
 #include <linux/debugfs.h>
 #include <linux/fsnotify.h>
+#include <linux/kprobes.h>
 
 #define DEBUGFS_MAGIC	0x64626720
 
@@ -320,6 +321,9 @@ static int __init debugfs_init(void)
 	retval = register_filesystem(&debug_fs_type);
 	if (retval)
 		subsystem_unregister(&debug_subsys);
+#ifdef CONFIG_KPROBES
+	debugfs_kprobe_init();
+#endif
 	return retval;
 }
 
Index: linux-2.6.20/kernel/kprobes.c
===================================================================
--- linux-2.6.20.orig/kernel/kprobes.c
+++ linux-2.6.20/kernel/kprobes.c
@@ -39,6 +39,8 @@
 #include <linux/moduleloader.h>
 #include <linux/kallsyms.h>
 #include <linux/freezer.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
 #include <asm-generic/sections.h>
 #include <asm/cacheflush.h>
 #include <asm/errno.h>
@@ -815,6 +817,96 @@ static int __init init_kprobes(void)
 	return err;
 }
 
+static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
+               const char *sym, int offset,char *modname)
+{
+	char *kprobe_type;
+
+	if (p->pre_handler == pre_handler_kretprobe)
+		kprobe_type = "r";
+	else if (p->pre_handler == setjmp_pre_handler)
+		kprobe_type = "j";
+	else
+		kprobe_type = "k";
+	if (sym)
+		seq_printf(pi, "%p  %s  %s+0x%x  %s\n", p->addr, kprobe_type,
+			sym, offset, (modname ? modname : " "));
+	else
+		seq_printf(pi, "%p  %s  %p\n", p->addr, kprobe_type, p->addr);
+}
+
+void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
+{
+	return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
+}
+
+void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
+{
+	(*pos)++;
+	if (*pos >= KPROBE_TABLE_SIZE)
+		return NULL;
+	return pos;
+}
+
+void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
+{
+	/* Nothing to do */
+}
+
+int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
+{
+	struct hlist_head *head;
+	struct hlist_node *node;
+	struct kprobe *p, *kp;
+	unsigned int i = *(loff_t *) v;
+	unsigned long size, offset = 0;
+	char *modname, namebuf[128];
+	const char *sym = NULL;
+
+	head = &kprobe_table[i];
+	preempt_disable();
+	hlist_for_each_entry_rcu(p, node, head, hlist) {
+		sym = kallsyms_lookup((unsigned long)p->addr, &size,
+					&offset, &modname, namebuf);
+		if (p->pre_handler == aggr_pre_handler) {
+			list_for_each_entry_rcu(kp, &p->list, list)
+				report_probe(pi, kp, sym, offset, modname);
+		} else
+			report_probe(pi, p, sym, offset, modname);
+	}
+	preempt_enable();
+	return 0;
+}
+
+struct seq_operations kprobes_seq_ops = {
+	.start = kprobe_seq_start,
+	.next  = kprobe_seq_next,
+	.stop  = kprobe_seq_stop,
+	.show  = show_kprobe_addr
+};
+
+static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
+{
+	return seq_open(filp, &kprobes_seq_ops);
+}
+
+static struct file_operations proc_kprobes_operations = {
+	.open           = kprobes_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = seq_release,
+};
+
+void __kprobes debugfs_kprobe_init(void)
+{
+	struct dentry *dir;
+	
+	dir = debugfs_create_dir("kprobes", NULL);
+	if (dir == NULL)
+		return;
+	debugfs_create_file("list", 0444, dir , 0 , &proc_kprobes_operations);
+}
+
 __initcall(init_kprobes);
 
 EXPORT_SYMBOL_GPL(register_kprobe);
Index: linux-2.6.20/include/linux/kprobes.h
===================================================================
--- linux-2.6.20.orig/include/linux/kprobes.h
+++ linux-2.6.20/include/linux/kprobes.h
@@ -203,6 +203,7 @@ struct kretprobe_instance *get_free_rp_i
 void add_rp_inst(struct kretprobe_instance *ri);
 void kprobe_flush_task(struct task_struct *tk);
 void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head);
+void debugfs_kprobe_init(void);
 #else /* CONFIG_KPROBES */
 
 #define __kprobes	/**/
@@ -240,5 +241,8 @@ static inline void unregister_kretprobe(
 static inline void kprobe_flush_task(struct task_struct *tk)
 {
 }
+static inline void proc_kprobe_init(void)
+{
+}
 #endif				/* CONFIG_KPROBES */
 #endif				/* _LINUX_KPROBES_H */