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
10 struct cpu_features cpu;
11 u32 cpu_vendor[3];
12
13 static bool loaded_flags;
14
15 static 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
47 int 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 void cpuid_count(u32 id, u32 count, u32 *a, u32 *b, u32 *c, u32 *d)
68 {
69 asm volatile("cpuid"
70 : "=a" (*a), "=b" (*b), "=c" (*c), "=d" (*d)
71 : "" (id), "2" (count)
72 );
73 }
74
75 #define cpuid(id, a, b, c, d) cpuid_count(id, 0, a, b, c, d)
76
77 void get_cpuflags(void)
78 {
79 u32 max_intel_level, max_amd_level;
80 u32 tfms;
81 u32 ignored;
82
83 if (loaded_flags)
84 return;
85 loaded_flags = true;
86
87 if (has_fpu())
88 set_bit(X86_FEATURE_FPU, cpu.flags);
89
90 if (has_eflag(X86_EFLAGS_ID)) {
91 cpuid(0x0, &max_intel_level, &cpu_vendor[0], &cpu_vendor[2],
92 &cpu_vendor[1]);
93
94 if (max_intel_level >= 0x00000001 &&
95 max_intel_level <= 0x0000ffff) {
96 cpuid(0x1, &tfms, &ignored, &cpu.flags[4],
97 &cpu.flags[0]);
98 cpu.level = (tfms >> 8) & 15;
99 cpu.family = cpu.level;
100 cpu.model = (tfms >> 4) & 15;
101 if (cpu.level >= 6)
102 cpu.model += ((tfms >> 16) & 0xf) << 4;
103 }
104
105 if (max_intel_level >= 0x00000007) {
106 cpuid_count(0x00000007, 0, &ignored, &ignored,
107 &cpu.flags[16], &ignored);
108 }
109
110 cpuid(0x80000000, &max_amd_level, &ignored, &ignored,
111 &ignored);
112
113 if (max_amd_level >= 0x80000001 &&
114 max_amd_level <= 0x8000ffff) {
115 cpuid(0x80000001, &ignored, &ignored, &cpu.flags[6],
116 &cpu.flags[1]);
117 }
118 }
119 }
120
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