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path: root/arch/x86/lib/retpoline.S
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/* SPDX-License-Identifier: GPL-2.0 */

#include <linux/stringify.h>
#include <linux/linkage.h>
#include <asm/dwarf2.h>
#include <asm/cpufeatures.h>
#include <asm/alternative-asm.h>
#include <asm/export.h>
#include <asm/nospec-branch.h>

.macro THUNK reg
	.section .text.__x86.indirect_thunk

SYM_FUNC_START(__x86_indirect_thunk_\reg)
	CFI_STARTPROC
	JMP_NOSPEC %\reg
	CFI_ENDPROC
SYM_FUNC_END(__x86_indirect_thunk_\reg)
.endm

/*
 * Despite being an assembler file we can't just use .irp here
 * because __KSYM_DEPS__ only uses the C preprocessor and would
 * only see one instance of "__x86_indirect_thunk_\reg" rather
 * than one per register with the correct names. So we do it
 * the simple and nasty way...
 */
#define __EXPORT_THUNK(sym) _ASM_NOKPROBE(sym); EXPORT_SYMBOL(sym)
#define EXPORT_THUNK(reg) __EXPORT_THUNK(__x86_indirect_thunk_ ## reg)
#define GENERATE_THUNK(reg) THUNK reg ; EXPORT_THUNK(reg)

GENERATE_THUNK(_ASM_AX)
GENERATE_THUNK(_ASM_BX)
GENERATE_THUNK(_ASM_CX)
GENERATE_THUNK(_ASM_DX)
GENERATE_THUNK(_ASM_SI)
GENERATE_THUNK(_ASM_DI)
GENERATE_THUNK(_ASM_BP)
#ifdef CONFIG_64BIT
GENERATE_THUNK(r8)
GENERATE_THUNK(r9)
GENERATE_THUNK(r10)
GENERATE_THUNK(r11)
GENERATE_THUNK(r12)
GENERATE_THUNK(r13)
GENERATE_THUNK(r14)
GENERATE_THUNK(r15)
#endif