1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
|
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_STATIC_CALL_H
#define _ASM_STATIC_CALL_H
#include <asm/text-patching.h>
/*
* For CONFIG_HAVE_STATIC_CALL_INLINE, this is a temporary trampoline which
* uses the current value of the key->func pointer to do an indirect jump to
* the function. This trampoline is only used during boot, before the call
* sites get patched by static_call_update(). The name of this trampoline has
* a magical aspect: objtool uses it to find static call sites so it can create
* the .static_call_sites section.
*
* For CONFIG_HAVE_STATIC_CALL, this is a permanent trampoline which
* does a direct jump to the function. The direct jump gets patched by
* static_call_update().
*
* Having the trampoline in a special section forces GCC to emit a JMP.d32 when
* it does tail-call optimization on the call; since you cannot compute the
* relative displacement across sections.
*/
#define __ARCH_DEFINE_STATIC_CALL_TRAMP(name, insns) \
asm(".pushsection .static_call.text, \"ax\" \n" \
".align 4 \n" \
".globl " STATIC_CALL_TRAMP_STR(name) " \n" \
STATIC_CALL_TRAMP_STR(name) ": \n" \
insns " \n" \
".byte 0x53, 0x43, 0x54 \n" \
".type " STATIC_CALL_TRAMP_STR(name) ", @function \n" \
".size " STATIC_CALL_TRAMP_STR(name) ", . - " STATIC_CALL_TRAMP_STR(name) " \n" \
".popsection \n")
#define ARCH_DEFINE_STATIC_CALL_TRAMP(name, func) \
__ARCH_DEFINE_STATIC_CALL_TRAMP(name, ".byte 0xe9; .long " #func " - (. + 4)")
#define ARCH_DEFINE_STATIC_CALL_NULL_TRAMP(name) \
__ARCH_DEFINE_STATIC_CALL_TRAMP(name, "ret; int3; nop; nop; nop")
#define ARCH_DEFINE_STATIC_CALL_RET0_TRAMP(name) \
ARCH_DEFINE_STATIC_CALL_TRAMP(name, __static_call_return0)
#define ARCH_ADD_TRAMP_KEY(name) \
asm(".pushsection .static_call_tramp_key, \"a\" \n" \
".long " STATIC_CALL_TRAMP_STR(name) " - . \n" \
".long " STATIC_CALL_KEY_STR(name) " - . \n" \
".popsection \n")
#endif /* _ASM_STATIC_CALL_H */
|
