/* 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. */ /* * The trampoline is 8 bytes and of the general form: * * jmp.d32 \func * ud1 %esp, %ecx * * That trailing #UD provides both a speculation stop and serves as a unique * 3 byte signature identifying static call trampolines. Also see tramp_ud[] * and __static_call_fixup(). */ #define __ARCH_DEFINE_STATIC_CALL_TRAMP(name, insns) … #define ARCH_DEFINE_STATIC_CALL_TRAMP(name, func) … #ifdef CONFIG_MITIGATION_RETHUNK #define ARCH_DEFINE_STATIC_CALL_NULL_TRAMP(name) … #else #define ARCH_DEFINE_STATIC_CALL_NULL_TRAMP … #endif #define ARCH_DEFINE_STATIC_CALL_RET0_TRAMP(name) … #define ARCH_ADD_TRAMP_KEY(name) … extern bool __static_call_fixup(void *tramp, u8 op, void *dest); #endif /* _ASM_STATIC_CALL_H */
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