Newly introduced function kprobe_on_ftrace_get_old_insn() will be
called by ftrace when ftrace generating call instruction. It is for
retriving probed instructions which original nops are replaced by
kprobe. FTRACE_FL_EARLY_KPROBES bit in rec->flags is cleared, so after
calling kprobe_on_ftrace_get_old_insn() an ftrace record will not be
treated as early kprobed.
Signed-off-by: Wang Nan <wangn...@huawei.com>
---
include/linux/kprobes.h | 9 +++++++++
kernel/kprobes.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 43 insertions(+)
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 5a5290f..2d78bbb 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -289,6 +289,8 @@ extern const unsigned char
*arch_kprobe_on_ftrace_get_old_insn(struct kprobe *kp
extern void init_kprobes_on_ftrace(void);
extern bool kprobe_fix_ftrace_make_nop(struct dyn_ftrace *rec);
+extern const unsigned char *kprobe_on_ftrace_get_old_insn(struct dyn_ftrace
*rec,
+ const unsigned char *ftrace_nop, unsigned char *dest, size_t
insn_size);
#else
static inline void init_kprobes_on_ftrace(void)
{
@@ -299,6 +301,13 @@ static inline bool kprobe_fix_ftrace_make_nop(struct
dyn_ftrace *_unused)
return false;
}
+
+static inline const unsigned char *
+kprobe_on_ftrace_get_old_insn(struct dyn_ftrace *_unused,
+ const unsigned char *ftrace_nop, unsigned char *_unused2,
size_t _unused3)
+{
+ return ftrace_nop;
+}
#endif // CONFIG_EARLY_KPROBES && CONFIG_KPROBES_ON_FTRACE
#ifdef CONFIG_EARLY_KPROBES
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 20b6ab8..c504c1c 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2623,6 +2623,40 @@ bool kprobe_fix_ftrace_make_nop(struct dyn_ftrace *rec)
return true;
}
+/* NOTE: caller must ensure holding kprobe_mutex */
+const unsigned char *
+kprobe_on_ftrace_get_old_insn(struct dyn_ftrace *rec,
+ const unsigned char *ftrace_nop,
+ unsigned char *dest, size_t insn_size)
+{
+ const unsigned char *ret;
+ struct kprobe *kp;
+ void *addr;
+
+ if (!(rec->flags & FTRACE_FL_EARLY_KPROBES))
+ return ftrace_nop;
+
+ addr = (void *)rec->ip;
+
+ /*
+ * Note that get_kprobe always get the kprobe on table, for it
+ * KPROBE_FLAG_OPTIMIZED is reliable.
+ */
+ kp = get_kprobe(addr);
+
+ if (!kp || !(kp->flags & KPROBE_FLAG_FTRACE_EARLY)) {
+ mutex_unlock(&kprobe_mutex);
+ return ftrace_nop;
+ }
+
+ ret = arch_kprobe_on_ftrace_get_old_insn(kp, ftrace_nop,
+ dest, insn_size);
+
+ /* Only give one chance for kprobe to retrive old insn. */
+ rec->flags &= ~FTRACE_FL_EARLY_KPROBES;
+ return ret;
+}
+
void init_kprobes_on_ftrace(void)
{
kprobes_on_ftrace_initialized = true;
--
1.8.4
--
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