[PATCH 06/13] samples/kprobes: Add support for multi kprobe interface

Jiri Olsa
2022-01-04T08:10:33Z

Adding support to test multi kprobe interface. It's now possible
to register multiple functions for the module handler, like:

# modprobe kprobe_example symbol='sched_fork,kernel_clone'

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
samples/kprobes/kprobe_example.c | 47 +++++++++++++++++++++++++++++---
1 file changed, 43 insertions(+), 4 deletions(-)

diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
index f991a66b5b02..4ae31184f098 100644
--- a/samples/kprobes/kprobe_example.c
+++ b/samples/kprobes/kprobe_example.c
@@ -15,8 +15,10 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/kprobes.h>
+#include <linux/slab.h>
+#include <linux/string.h>

-#define MAX_SYMBOL_LEN 64
+#define MAX_SYMBOL_LEN 4096
static char symbol[MAX_SYMBOL_LEN] = "kernel_clone";
module_param_string(symbol, symbol, sizeof(symbol), 0644);

@@ -97,17 +99,54 @@ static void __kprobes handler_post(struct kprobe *p, struct pt_regs *regs,

static int __init kprobe_init(void)
{
+ char **symbols = NULL;
int ret;
+
kp.pre_handler = handler_pre;
kp.post_handler = handler_post;

+#ifdef CONFIG_HAVE_KPROBES_MULTI_ON_FTRACE
+ if (strchr(symbol, ',')) {
+ char *p, *tmp;
+ int cnt;
+
+ tmp = kstrdup(symbol, GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;
+
+ p = strchr(tmp, ',');
+ while (p) {
+ *p = ' ';
+ p = strchr(p + 1, ',');
+ }
+
+ symbols = argv_split(GFP_KERNEL, tmp, &cnt);
+ kfree(tmp);
+ if (!symbols) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ kp.multi.symbols = (const char **) symbols;
+ kp.multi.cnt = cnt;
+ }
+#endif
+
ret = register_kprobe(&kp);
if (ret < 0) {
pr_err("register_kprobe failed, returned %d\n", ret);
- return ret;
+ goto out;
}
- pr_info("Planted kprobe at %p\n", kp.addr);
- return 0;
+
+ if (symbols)
+ pr_info("Planted multi kprobe to %s\n", symbol);
+ else
+ pr_info("Planted kprobe at %p\n", kp.addr);
+
+out:
+ if (symbols)
+ argv_free(symbols);
+ return ret;
}

static void __exit kprobe_exit(void)
--
2.33.1