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 | : "0" (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, addr: 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(id: 0x00000007, count: 0, a: &ignored, b: &ignored, |
107 | c: &cpu.flags[16], d: &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 | |