1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Static locals of three kinds, in one patched function.
4 *
5 * Most static locals must be correlated, so the patched code keeps using the
6 * running kernel's copy. Two kinds must not:
7 *
8 * - anything in .data..once, the flag behind WARN_ONCE and friends. Sharing
9 * it would mean a patch inherits "already warned" from before the patch.
10 * - the well-known names the kernel generates for such things (__warned,
11 * __key, __func__, ...), which are per-instance by nature. gcc names them
12 * <var>.<id> and Clang <func>.<var>, so both spellings have to be caught.
13 */
14
15 static const char __modinfo[]
16 __attribute__((section(".modinfo"), used, aligned(1))) = "\0name=vmlinux";
17
target(int x)18 int target(int x)
19 {
20 /*
21 * A .data..once variable whose name is *not* on the list below, so
22 * only the section can disqualify it. Naming it __warned would let
23 * the name rule catch it and the section rule go untested.
24 */
25 static int once_flag __attribute__((section(".data..once")));
26 /* a never-correlate name, in an ordinary section */
27 static int __key;
28 /* and one that must be correlated */
29 static int ordinary;
30
31 if (!once_flag)
32 once_flag = 1;
33 __key += x;
34 ordinary += x;
35
36 #ifdef PATCHED
37 return __key + ordinary + once_flag + 2;
38 #else
39 return __key + ordinary + once_flag + 1;
40 #endif
41 }
42