1/* SPDX-License-Identifier: GPL-2.0-only */
2#ifndef _ASM_X86_GSSEG_H
3#define _ASM_X86_GSSEG_H
4
5#include <linux/types.h>
6
7#include <asm/asm.h>
8#include <asm/cpufeature.h>
9#include <asm/alternative.h>
10#include <asm/processor.h>
11#include <asm/nops.h>
12
13#ifdef CONFIG_X86_64
14
15extern asmlinkage void asm_load_gs_index(u16 selector);
16
17/* Replace with "lkgs %di" once binutils support LKGS instruction */
18#define LKGS_DI _ASM_BYTES(0xf2,0x0f,0x00,0xf7)
19
20static inline void native_lkgs(unsigned int selector)
21{
22 u16 sel = selector;
23 asm_inline volatile("1: " LKGS_DI
24 _ASM_EXTABLE_TYPE_REG(1b, 1b, EX_TYPE_ZERO_REG, %k[sel])
25 : [sel] "+D" (sel));
26}
27
28static inline void native_load_gs_index(unsigned int selector)
29{
30 if (cpu_feature_enabled(X86_FEATURE_LKGS)) {
31 native_lkgs(selector);
32 } else {
33 unsigned long flags;
34
35 local_irq_save(flags);
36 asm_load_gs_index(selector);
37 local_irq_restore(flags);
38 }
39}
40
41#endif /* CONFIG_X86_64 */
42
43static inline void __init lkgs_init(void)
44{
45#ifdef CONFIG_PARAVIRT_XXL
46#ifdef CONFIG_X86_64
47 if (cpu_feature_enabled(X86_FEATURE_LKGS))
48 pv_ops.cpu.load_gs_index = native_lkgs;
49#endif
50#endif
51}
52
53#ifndef CONFIG_PARAVIRT_XXL
54
55static inline void load_gs_index(unsigned int selector)
56{
57#ifdef CONFIG_X86_64
58 native_load_gs_index(selector);
59#else
60 loadsegment(gs, selector);
61#endif
62}
63
64#endif /* CONFIG_PARAVIRT_XXL */
65
66#endif /* _ASM_X86_GSSEG_H */
67