Linux kernel mirror (for testing)
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linux
1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_RUNTIME_CONST_H
3#define _ASM_RUNTIME_CONST_H
4
5#ifdef MODULE
6 #error "Cannot use runtime-const infrastructure from modules"
7#endif
8
9#ifdef __ASSEMBLY__
10
11.macro RUNTIME_CONST_PTR sym reg
12 movq $0x0123456789abcdef, %\reg
13 1:
14 .pushsection runtime_ptr_\sym, "a"
15 .long 1b - 8 - .
16 .popsection
17.endm
18
19#else /* __ASSEMBLY__ */
20
21#define runtime_const_ptr(sym) ({ \
22 typeof(sym) __ret; \
23 asm_inline("mov %1,%0\n1:\n" \
24 ".pushsection runtime_ptr_" #sym ",\"a\"\n\t" \
25 ".long 1b - %c2 - .\n" \
26 ".popsection" \
27 :"=r" (__ret) \
28 :"i" ((unsigned long)0x0123456789abcdefull), \
29 "i" (sizeof(long))); \
30 __ret; })
31
32// The 'typeof' will create at _least_ a 32-bit type, but
33// will happily also take a bigger type and the 'shrl' will
34// clear the upper bits
35#define runtime_const_shift_right_32(val, sym) ({ \
36 typeof(0u+(val)) __ret = (val); \
37 asm_inline("shrl $12,%k0\n1:\n" \
38 ".pushsection runtime_shift_" #sym ",\"a\"\n\t" \
39 ".long 1b - 1 - .\n" \
40 ".popsection" \
41 :"+r" (__ret)); \
42 __ret; })
43
44#define runtime_const_init(type, sym) do { \
45 extern s32 __start_runtime_##type##_##sym[]; \
46 extern s32 __stop_runtime_##type##_##sym[]; \
47 runtime_const_fixup(__runtime_fixup_##type, \
48 (unsigned long)(sym), \
49 __start_runtime_##type##_##sym, \
50 __stop_runtime_##type##_##sym); \
51} while (0)
52
53/*
54 * The text patching is trivial - you can only do this at init time,
55 * when the text section hasn't been marked RO, and before the text
56 * has ever been executed.
57 */
58static inline void __runtime_fixup_ptr(void *where, unsigned long val)
59{
60 *(unsigned long *)where = val;
61}
62
63static inline void __runtime_fixup_shift(void *where, unsigned long val)
64{
65 *(unsigned char *)where = val;
66}
67
68static inline void runtime_const_fixup(void (*fn)(void *, unsigned long),
69 unsigned long val, s32 *start, s32 *end)
70{
71 while (start < end) {
72 fn(*start + (void *)start, val);
73 start++;
74 }
75}
76
77#endif /* __ASSEMBLY__ */
78#endif