kprobes: Add new KPROBE_FLAG_ON_FUNC_ENTRY kprobe flag

Adding KPROBE_FLAG_ON_FUNC_ENTRY kprobe flag to indicate that
attach address is on function entry. This is used in following
changes in get_func_ip helper to return correct function address.

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20220926153340.1621984-2-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 55041d2..a0b92be 100644 (file)
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -103,6 +103,7 @@ struct kprobe {
                                   * this flag is only for optimized_kprobe.
                                   */
 #define KPROBE_FLAG_FTRACE     8 /* probe is using ftrace */
+#define KPROBE_FLAG_ON_FUNC_ENTRY      16 /* probe is on the function entry */
 
 /* Has this kprobe gone ? */
 static inline bool kprobe_gone(struct kprobe *p)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 08350e3..51adc3c 100644 (file)
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1606,9 +1606,10 @@ int register_kprobe(struct kprobe *p)
        struct kprobe *old_p;
        struct module *probed_mod;
        kprobe_opcode_t *addr;
+       bool on_func_entry;
 
        /* Adjust probe address from symbol */
-       addr = kprobe_addr(p);
+       addr = _kprobe_addr(p->addr, p->symbol_name, p->offset, &on_func_entry);
        if (IS_ERR(addr))
                return PTR_ERR(addr);
        p->addr = addr;
@@ -1628,6 +1629,9 @@ int register_kprobe(struct kprobe *p)
 
        mutex_lock(&kprobe_mutex);
 
+       if (on_func_entry)
+               p->flags |= KPROBE_FLAG_ON_FUNC_ENTRY;
+
        old_p = get_kprobe(p->addr);
        if (old_p) {
                /* Since this may unoptimize 'old_p', locking 'text_mutex'. */