This patch shows a very rough usage of arly kprobes. By adding
kernel cmdline options such as 'ekprobe=__alloc_pages_nodemask' or
'ekprobe=0xc00f3c2c', early kprobes are installed. When the probed
instructions get hit, a message is printed.
This patch is only a sample. I'll drop it in future.
Signed-off-by: Wang Nan <wangn...@huawei.com>
---
kernel/kprobes.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 84 insertions(+)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 95754f6..56fb8c8 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2224,9 +2224,12 @@ static struct notifier_block kprobe_module_nb = {
.priority = 0
};
+static LIST_HEAD(cmdline_early_kprobes_list);
+
void init_kprobes_early(void)
{
int i, err = 0;
+ struct kprobe *early_kp, *tmp;
/* FIXME allocate the probe table, currently defined statically */
/* initialize all list heads */
@@ -2270,6 +2273,16 @@ void init_kprobes_early(void)
if (!err)
init_test_probes();
#endif
+
+ list_for_each_entry_safe(early_kp, tmp, &cmdline_early_kprobes_list,
list) {
+ int ret;
+
+ list_del(&early_kp->list);
+ INIT_LIST_HEAD(&early_kp->list);
+ ret = register_kprobe(early_kp);
+ printk("early kprobe: register early kprobe at %p: result =
%d\n",
+ early_kp->addr, ret);
+ }
}
static int __init init_kprobes(void)
@@ -2724,3 +2737,74 @@ void init_kprobes_on_ftrace(void)
convert_early_kprobes_on_ftrace();
}
#endif
+
+#ifdef CONFIG_EARLY_KPROBES
+static int early_kprobe_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ const char *sym = NULL;
+ char *modname, namebuf[KSYM_NAME_LEN];
+ unsigned long offset = 0;
+
+ sym = kallsyms_lookup((unsigned long)p->addr, NULL,
+ &offset, &modname, namebuf);
+ if (sym)
+ pr_info("Hit early kprobe at %s+0x%lx%s%s\n",
+ sym, offset,
+ (modname ? " " : ""),
+ (modname ? modname : ""));
+ else
+ pr_info("Hit early kprobe at %p\n", p->addr);
+ return 0;
+}
+
+DEFINE_EKPROBE_ALLOC_OPS(struct kprobe, early_kprobe_setup, static);
+static int __init early_kprobe_setup(char *p)
+{
+ unsigned long long addr;
+ struct kprobe *kp;
+ int len = strlen(p);
+ int err;
+
+ if (len <= 0) {
+ pr_err("early kprobe: wrong param: %s\n", p);
+ return 0;
+ }
+
+ if ((p[0] == '0') && (p[1] == 'x')) {
+ err = kstrtoull(p, 16, &addr);
+ if (err) {
+ pr_err("early kprobe: wrong address: %p\n", p);
+ return 0;
+ }
+ } else {
+ addr = kallsyms_lookup_name(p);
+ if (!addr) {
+ pr_err("early kprobe: wrong symbol: %s\n", p);
+ return 0;
+ }
+ }
+
+ if ((addr < (unsigned long)_text) ||
+ (addr >= (unsigned long)_etext))
+ pr_err("early kprobe: address of %p out of range\n", p);
+
+ kp = ek_alloc_early_kprobe_setup();
+ if (kp == NULL) {
+ pr_err("early kprobe: no enough early kprobe slot\n");
+ return 0;
+ }
+ kp->addr = (void *)(unsigned long)(addr);
+ kp->pre_handler = early_kprobe_pre_handler;
+
+ list_add(&kp->list, &cmdline_early_kprobes_list);
+
+ return 0;
+}
+#else
+static int __init early_kprobe_setup(char *p)
+{
+ return 0;
+}
+#endif
+
+early_param("ekprobe", early_kprobe_setup);
--
1.8.4
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