1 /* SPDX-License-Identifier: GPL-2.0 */ 1
2 #ifndef __LINUX_INSTRUMENTATION_H
3 #define __LINUX_INSTRUMENTATION_H
4
5 #ifdef CONFIG_NOINSTR_VALIDATION
6
7 #include <linux/stringify.h>
8
9 /* Begin/end of an instrumentation safe region
10 #define __instrumentation_begin(c) ({
11 asm volatile(__stringify(c) ": nop\n\t
12 ".pushsection .discard.in
13 ".long " __stringify(c) "
14 ".popsection\n\t" : : "i"
15 })
16 #define instrumentation_begin() __instrumentat
17
18 /*
19 * Because instrumentation_{begin,end}() can n
20 * _begin() a +1 and _end() a -1 and computes
21 * When the value is greater than 0, we consid
22 *
23 * There is a problem with code like:
24 *
25 * noinstr void foo()
26 * {
27 * instrumentation_begin();
28 * ...
29 * if (cond) {
30 * instrumentation_begin();
31 * ...
32 * instrumentation_end();
33 * }
34 * bar();
35 * instrumentation_end();
36 * }
37 *
38 * If instrumentation_end() would be an empty
39 * annotations, the inner _end(), which is at
40 * would land on the instruction after the blo
41 *
42 * If we then consider the sum of the !cond pa
43 * bar() is with a 0-value, even though, we me
44 * value.
45 *
46 * To avoid this, have _end() be a NOP instruc
47 * part of the condition block and does not es
48 */
49 #define __instrumentation_end(c) ({
50 asm volatile(__stringify(c) ": nop\n\t
51 ".pushsection .discard.in
52 ".long " __stringify(c) "
53 ".popsection\n\t" : : "i"
54 })
55 #define instrumentation_end() __instrumentatio
56 #else /* !CONFIG_NOINSTR_VALIDATION */
57 # define instrumentation_begin() do { }
58 # define instrumentation_end() do { }
59 #endif /* CONFIG_NOINSTR_VALIDATION */
60
61 #endif /* __LINUX_INSTRUMENTATION_H */
62
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