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 
has_fpu(void)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 
has_eflag(unsigned long mask)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 
cpuid_count(u32 id,u32 count,u32 * a,u32 * b,u32 * c,u32 * d)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 
get_cpuflags(void)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