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
67void 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
77void 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