1// SPDX-License-Identifier: GPL-2.0
2#include <linux/types.h>
3#include "bitops.h"
4
5#include <asm/processor-flags.h>
6#include <asm/required-features.h>
7#include <asm/msr-index.h>
8#include "cpuflags.h"
9
10struct cpu_features cpu;
11u32 cpu_vendor[3];
12
13static bool loaded_flags;
14
15static int has_fpu(void)
16{
17 u16 fcw = -1, fsw = -1;
18 unsigned long cr0;
19
20 asm volatile("mov %%cr0,%0" : "=r" (cr0));
21 if (cr0 & (X86_CR0_EM|X86_CR0_TS)) {
22 cr0 &= ~(X86_CR0_EM|X86_CR0_TS);
23 asm volatile("mov %0,%%cr0" : : "r" (cr0));
24 }
25
26 asm volatile("fninit ; fnstsw %0 ; fnstcw %1"
27 : "+m" (fsw), "+m" (fcw));
28
29 return fsw == 0 && (fcw & 0x103f) == 0x003f;
30}
31
32/*
33 * For building the 16-bit code we want to explicitly specify 32-bit
34 * push/pop operations, rather than just saying 'pushf' or 'popf' and
35 * letting the compiler choose. But this is also included from the
36 * compressed/ directory where it may be 64-bit code, and thus needs
37 * to be 'pushfq' or 'popfq' in that case.
38 */
39#ifdef __x86_64__
40#define PUSHF "pushfq"
41#define POPF "popfq"
42#else
43#define PUSHF "pushfl"
44#define POPF "popfl"
45#endif
46
47int has_eflag(unsigned long mask)
48{
49 unsigned long f0, f1;
50
51 asm volatile(PUSHF " \n\t"
52 PUSHF " \n\t"
53 "pop %0 \n\t"
54 "mov %0,%1 \n\t"
55 "xor %2,%1 \n\t"
56 "push %1 \n\t"
57 POPF " \n\t"
58 PUSHF " \n\t"
59 "pop %1 \n\t"
60 POPF
61 : "=&r" (f0), "=&r" (f1)
62 : "ri" (mask));
63
64 return !!((f0^f1) & mask);
65}
66
67/* Handle x86_32 PIC using ebx. */
68#if defined(__i386__) && defined(__PIC__)
69# define EBX_REG "=r"
70#else
71# define EBX_REG "=b"
72#endif
73
74static inline void cpuid_count(u32 id, u32 count,
75 u32 *a, u32 *b, u32 *c, u32 *d)
76{
77 asm volatile(".ifnc %%ebx,%3 ; movl %%ebx,%3 ; .endif \n\t"
78 "cpuid \n\t"
79 ".ifnc %%ebx,%3 ; xchgl %%ebx,%3 ; .endif \n\t"
80 : "=a" (*a), "=c" (*c), "=d" (*d), EBX_REG (*b)
81 : "a" (id), "c" (count)
82 );
83}
84
85#define cpuid(id, a, b, c, d) cpuid_count(id, 0, a, b, c, d)
86
87void get_cpuflags(void)
88{
89 u32 max_intel_level, max_amd_level;
90 u32 tfms;
91 u32 ignored;
92
93 if (loaded_flags)
94 return;
95 loaded_flags = true;
96
97 if (has_fpu())
98 set_bit(X86_FEATURE_FPU, cpu.flags);
99
100 if (has_eflag(X86_EFLAGS_ID)) {
101 cpuid(0x0, &max_intel_level, &cpu_vendor[0], &cpu_vendor[2],
102 &cpu_vendor[1]);
103
104 if (max_intel_level >= 0x00000001 &&
105 max_intel_level <= 0x0000ffff) {
106 cpuid(0x1, &tfms, &ignored, &cpu.flags[4],
107 &cpu.flags[0]);
108 cpu.level = (tfms >> 8) & 15;
109 cpu.family = cpu.level;
110 cpu.model = (tfms >> 4) & 15;
111 if (cpu.level >= 6)
112 cpu.model += ((tfms >> 16) & 0xf) << 4;
113 }
114
115 if (max_intel_level >= 0x00000007) {
116 cpuid_count(0x00000007, 0, &ignored, &ignored,
117 &cpu.flags[16], &ignored);
118 }
119
120 cpuid(0x80000000, &max_amd_level, &ignored, &ignored,
121 &ignored);
122
123 if (max_amd_level >= 0x80000001 &&
124 max_amd_level <= 0x8000ffff) {
125 cpuid(0x80000001, &ignored, &ignored, &cpu.flags[6],
126 &cpu.flags[1]);
127 }
128 }
129}
130