[PATCH] uprobes: list all active uprobes in the system
From: luolongjun
Date: Wed Jan 11 2023 - 05:49:52 EST
From: Longjun Luo <luolongjun@xxxxxxxxxx>
Since uprobes will replace instructions in the process
memory, it is necessary to provide one way to list
all active uprobes. One can access this file through
/sys/kernel/debug/uprobes/list.
Output looks like this
=====================
inode+offset/ref_ctr_offset 4160760670+0x30a10/0x0
ref 1
register_rwsem (unlocked)
consumer_rwsem (unlocked)
consumers-1
handler 0xffffffffc03ee02e(handler) uprobe
ret_handler 0x0000000000000000( )
filter 0xffffffffc03ee010(filter) uprobe
consumers-2
handler 0xffffffffc03e902e(handler_1) uprobe_1
ret_handler 0x0000000000000000( )
filter 0xffffffffc03e9010(filter_1) uprobe_1
Signed-off-by: Longjun Luo <luolongjun@xxxxxxxxxx>
---
kernel/events/uprobes.c | 120 ++++++++++++++++++++++++++++++++++++----
1 file changed, 109 insertions(+), 11 deletions(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index d9e357b7e17c..2fa9b910abc7 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -27,6 +27,9 @@
#include <linux/task_work.h>
#include <linux/shmem_fs.h>
#include <linux/khugepaged.h>
+#include <linux/rbtree.h>
+#include <linux/debugfs.h>
+#include <linux/kallsyms.h>
#include <linux/uprobes.h>
@@ -40,7 +43,7 @@ static struct rb_root uprobes_tree = RB_ROOT;
*/
#define no_uprobe_events() RB_EMPTY_ROOT(&uprobes_tree)
-static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */
+static DECLARE_RWSEM(uprobes_treelock); /* serialize rbtree access */
#define UPROBES_HASH_SZ 13
/* serialize uprobe->pending_list */
@@ -672,9 +675,9 @@ static struct uprobe *find_uprobe(struct inode *inode, loff_t offset)
{
struct uprobe *uprobe;
- spin_lock(&uprobes_treelock);
+ down_read(&uprobes_treelock);
uprobe = __find_uprobe(inode, offset);
- spin_unlock(&uprobes_treelock);
+ up_read(&uprobes_treelock);
return uprobe;
}
@@ -704,9 +707,9 @@ static struct uprobe *insert_uprobe(struct uprobe *uprobe)
{
struct uprobe *u;
- spin_lock(&uprobes_treelock);
+ down_write(&uprobes_treelock);
u = __insert_uprobe(uprobe);
- spin_unlock(&uprobes_treelock);
+ up_write(&uprobes_treelock);
return u;
}
@@ -938,9 +941,9 @@ static void delete_uprobe(struct uprobe *uprobe)
if (WARN_ON(!uprobe_is_active(uprobe)))
return;
- spin_lock(&uprobes_treelock);
+ down_write(&uprobes_treelock);
rb_erase(&uprobe->rb_node, &uprobes_tree);
- spin_unlock(&uprobes_treelock);
+ up_write(&uprobes_treelock);
RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */
put_uprobe(uprobe);
}
@@ -1301,7 +1304,7 @@ static void build_probe_list(struct inode *inode,
min = vaddr_to_offset(vma, start);
max = min + (end - start) - 1;
- spin_lock(&uprobes_treelock);
+ down_read(&uprobes_treelock);
n = find_node_in_range(inode, min, max);
if (n) {
for (t = n; t; t = rb_prev(t)) {
@@ -1319,7 +1322,7 @@ static void build_probe_list(struct inode *inode,
get_uprobe(u);
}
}
- spin_unlock(&uprobes_treelock);
+ up_read(&uprobes_treelock);
}
/* @vma contains reference counter, not the probed instruction. */
@@ -1410,9 +1413,9 @@ vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long e
min = vaddr_to_offset(vma, start);
max = min + (end - start) - 1;
- spin_lock(&uprobes_treelock);
+ down_read(&uprobes_treelock);
n = find_node_in_range(inode, min, max);
- spin_unlock(&uprobes_treelock);
+ up_read(&uprobes_treelock);
return !!n;
}
@@ -2357,3 +2360,98 @@ void __init uprobes_init(void)
BUG_ON(register_die_notifier(&uprobe_exception_nb));
}
+
+#ifdef CONFIG_DEBUG_FS
+
+static void *uprobe_seq_start(struct seq_file *m, loff_t *pos)
+{
+ loff_t num = *pos;
+ struct rb_node *rbp;
+
+ down_read(&uprobes_treelock);
+ for (rbp = rb_first(&uprobes_tree); rbp; rbp = rb_next(rbp)) {
+ if (num-- == 0)
+ return rbp;
+ }
+
+ return NULL;
+}
+
+static void *uprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
+{
+ ++*pos;
+ return (void *)rb_next(v);
+}
+
+static void uprobe_seq_stop(struct seq_file *f, void *v)
+{
+ up_read(&uprobes_treelock);
+}
+
+static int show_uprobe(struct seq_file *m, void *v)
+{
+ struct uprobe *uprobe = rb_entry_safe(v, struct uprobe, rb_node);
+ struct uprobe_consumer *con;
+ char *modname, namebuf[KSYM_NAME_LEN];
+ const char *sym;
+ unsigned int cnt = 1;
+
+ seq_printf(m, "inode+offset/ref_ctr_offset %lu+0x%llx/0x%llx\n",
+ uprobe->inode->i_ino, uprobe->offset, uprobe->ref_ctr_offset);
+ seq_printf(m, " ref %u\n",
+ refcount_read(&uprobe->ref));
+ seq_printf(m, " register_rwsem %s\n",
+ rwsem_is_locked(&uprobe->register_rwsem)?"(locked)":"(unlocked)");
+ seq_printf(m, " consumer_rwsem %s\n",
+ rwsem_is_locked(&uprobe->consumer_rwsem)?"(locked)":"(unlocked)");
+
+ /* lock consumer_rwsem when hold uprobes_treelock */
+ down_read(&uprobe->consumer_rwsem);
+ for (con = uprobe->consumers; con; con = con->next, cnt++) {
+ seq_printf(m, " consumers-%u\n", cnt);
+
+ modname = NULL;
+ sym = kallsyms_lookup((unsigned long)con->handler, NULL, NULL,
+ &modname, namebuf);
+ seq_printf(m, " handler 0x%px(%s) %s\n",
+ con->handler, (sym ? sym : " "), (modname ? modname : " "));
+
+ modname = NULL;
+ sym = kallsyms_lookup((unsigned long)con->ret_handler, NULL, NULL,
+ &modname, namebuf);
+ seq_printf(m, " ret_handler 0x%px(%s) %s\n",
+ con->ret_handler, (sym ? sym : " "), (modname ? modname : " "));
+
+ modname = NULL;
+ sym = kallsyms_lookup((unsigned long)con->filter, NULL, NULL,
+ &modname, namebuf);
+ seq_printf(m, " filter 0x%px(%s) %s\n",
+ con->filter, (sym ? sym : " "), (modname ? modname : " "));
+ }
+ up_read(&uprobe->consumer_rwsem);
+
+ return 0;
+}
+
+static const struct seq_operations uprobes_sops = {
+ .start = uprobe_seq_start,
+ .next = uprobe_seq_next,
+ .stop = uprobe_seq_stop,
+ .show = show_uprobe,
+};
+
+DEFINE_SEQ_ATTRIBUTE(uprobes);
+
+static int __init debugfs_uprobe_init(void)
+{
+ struct dentry *dir;
+
+ dir = debugfs_create_dir("uprobes", NULL);
+
+ debugfs_create_file("list", 0400, dir, NULL, &uprobes_fops);
+
+ return 0;
+}
+late_initcall(debugfs_uprobe_init);
+
+#endif /* CONFIG_DEBUG_FS */
--
2.38.1