Merge branch 'etnaviv/next' of https://git.pengutronix.de/git/lst/linux into drm...
[linux-2.6-microblaze.git] / arch / x86 / include / asm / static_call.h
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_STATIC_CALL_H
3 #define _ASM_STATIC_CALL_H
4
5 #include <asm/text-patching.h>
6
7 /*
8  * For CONFIG_HAVE_STATIC_CALL_INLINE, this is a temporary trampoline which
9  * uses the current value of the key->func pointer to do an indirect jump to
10  * the function.  This trampoline is only used during boot, before the call
11  * sites get patched by static_call_update().  The name of this trampoline has
12  * a magical aspect: objtool uses it to find static call sites so it can create
13  * the .static_call_sites section.
14  *
15  * For CONFIG_HAVE_STATIC_CALL, this is a permanent trampoline which
16  * does a direct jump to the function.  The direct jump gets patched by
17  * static_call_update().
18  *
19  * Having the trampoline in a special section forces GCC to emit a JMP.d32 when
20  * it does tail-call optimization on the call; since you cannot compute the
21  * relative displacement across sections.
22  */
23
24 #define __ARCH_DEFINE_STATIC_CALL_TRAMP(name, insns)                    \
25         asm(".pushsection .static_call.text, \"ax\"             \n"     \
26             ".align 4                                           \n"     \
27             ".globl " STATIC_CALL_TRAMP_STR(name) "             \n"     \
28             STATIC_CALL_TRAMP_STR(name) ":                      \n"     \
29             insns "                                             \n"     \
30             ".type " STATIC_CALL_TRAMP_STR(name) ", @function   \n"     \
31             ".size " STATIC_CALL_TRAMP_STR(name) ", . - " STATIC_CALL_TRAMP_STR(name) " \n" \
32             ".popsection                                        \n")
33
34 #define ARCH_DEFINE_STATIC_CALL_TRAMP(name, func)                       \
35         __ARCH_DEFINE_STATIC_CALL_TRAMP(name, ".byte 0xe9; .long " #func " - (. + 4)")
36
37 #define ARCH_DEFINE_STATIC_CALL_NULL_TRAMP(name)                        \
38         __ARCH_DEFINE_STATIC_CALL_TRAMP(name, "ret; nop; nop; nop; nop")
39
40
41 #define ARCH_ADD_TRAMP_KEY(name)                                        \
42         asm(".pushsection .static_call_tramp_key, \"a\"         \n"     \
43             ".long " STATIC_CALL_TRAMP_STR(name) " - .          \n"     \
44             ".long " STATIC_CALL_KEY_STR(name) " - .            \n"     \
45             ".popsection                                        \n")
46
47 #endif /* _ASM_STATIC_CALL_H */