xref: /PHP-8.3/Zend/zend_cpuinfo.c (revision 3a843f95)
1 /*
2    +----------------------------------------------------------------------+
3    | Zend Engine                                                          |
4    +----------------------------------------------------------------------+
5    | Copyright (c) Zend Technologies Ltd. (http://www.zend.com)           |
6    +----------------------------------------------------------------------+
7    | This source file is subject to version 2.00 of the Zend license,     |
8    | that is bundled with this package in the file LICENSE, and is        |
9    | available through the world-wide-web at the following url:           |
10    | http://www.zend.com/license/2_00.txt.                                |
11    | If you did not receive a copy of the Zend license and are unable to  |
12    | obtain it through the world-wide-web, please send a note to          |
13    | license@zend.com so we can mail you a copy immediately.              |
14    +----------------------------------------------------------------------+
15    | Authors: Xinchen Hui <xinchen.h@zend.com>                            |
16    +----------------------------------------------------------------------+
17 */
18 
19 #include "zend_cpuinfo.h"
20 
21 typedef struct _zend_cpu_info {
22 	uint32_t eax;
23 	uint32_t ebx;
24 	uint32_t ecx;
25 	uint32_t edx;
26 	uint32_t initialized;
27 } zend_cpu_info;
28 
29 static zend_cpu_info cpuinfo = {0};
30 
31 #if (defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__))
32 # if defined(HAVE_CPUID_H) && defined(HAVE_CPUID_COUNT) /* use cpuid.h functions */
33 #  include <cpuid.h>
__zend_cpuid(uint32_t func,uint32_t subfunc,zend_cpu_info * cpuinfo)34 static void __zend_cpuid(uint32_t func, uint32_t subfunc, zend_cpu_info *cpuinfo) {
35 	__cpuid_count(func, subfunc, cpuinfo->eax, cpuinfo->ebx, cpuinfo->ecx, cpuinfo->edx);
36 }
37 # else /* use inline asm */
__zend_cpuid(uint32_t func,uint32_t subfunc,zend_cpu_info * cpuinfo)38 static void __zend_cpuid(uint32_t func, uint32_t subfunc, zend_cpu_info *cpuinfo) {
39 #  if defined(__i386__) && (defined(__pic__) || defined(__PIC__))
40 	/* PIC on i386 uses %ebx, so preserve it. */
41 	__asm__ __volatile__ (
42 		"pushl  %%ebx\n"
43 		"cpuid\n"
44 		"mov    %%ebx,%1\n"
45 		"popl   %%ebx"
46 		: "=a"(cpuinfo->eax), "=r"(cpuinfo->ebx), "=c"(cpuinfo->ecx), "=d"(cpuinfo->edx)
47 		: "a"(func), "c"(subfunc)
48 	);
49 #  else
50 	__asm__ __volatile__ (
51 		"cpuid"
52 		: "=a"(cpuinfo->eax), "=b"(cpuinfo->ebx), "=c"(cpuinfo->ecx), "=d"(cpuinfo->edx)
53 		: "a"(func), "c"(subfunc)
54 	);
55 #  endif
56 }
57 # endif
58 #elif defined(_MSC_VER) && !defined(__clang__) && (defined(_M_X64) || defined(_M_IX86)) /* use MSVC __cpuidex intrin */
59 # include <intrin.h>
__zend_cpuid(uint32_t func,uint32_t subfunc,zend_cpu_info * cpuinfo)60 static void __zend_cpuid(uint32_t func, uint32_t subfunc, zend_cpu_info *cpuinfo) {
61 	int regs[4];
62 
63 	__cpuidex(regs, func, subfunc);
64 
65 	cpuinfo->eax = regs[0];
66 	cpuinfo->ebx = regs[1];
67 	cpuinfo->ecx = regs[2];
68 	cpuinfo->edx = regs[3];
69 }
70 #else /* fall back to zero */
__zend_cpuid(uint32_t func,uint32_t subfunc,zend_cpu_info * cpuinfo)71 static void __zend_cpuid(uint32_t func, uint32_t subfunc, zend_cpu_info *cpuinfo) {
72 	cpuinfo->eax = 0;
73 }
74 #endif
75 
76 #if defined(__i386__) || defined(__x86_64__)
77 /* Function based on compiler-rt implementation. */
get_xcr0_eax(void)78 static unsigned get_xcr0_eax(void) {
79 # if defined(__GNUC__) || defined(__clang__)
80 	// Check xgetbv; this uses a .byte sequence instead of the instruction
81 	// directly because older assemblers do not include support for xgetbv and
82 	// there is no easy way to conditionally compile based on the assembler used.
83 	unsigned eax, edx;
84 	__asm__(".byte 0x0f, 0x01, 0xd0" : "=a"(eax), "=d"(edx) : "c"(0));
85 	return eax;
86 # elif defined(ZEND_WIN32) && defined(_XCR_XFEATURE_ENABLED_MASK)
87 	return _xgetbv(_XCR_XFEATURE_ENABLED_MASK);
88 # else
89 	return 0;
90 # endif
91 }
92 
is_avx_supported(void)93 static bool is_avx_supported(void) {
94 	if (!(cpuinfo.ecx & ZEND_CPU_FEATURE_AVX)) {
95 		/* No support for AVX */
96 		return 0;
97 	}
98 	if (!(cpuinfo.ecx & ZEND_CPU_FEATURE_OSXSAVE)) {
99 		/* The operating system does not support XSAVE. */
100 		return 0;
101 	}
102 	if ((get_xcr0_eax() & 0x6) != 0x6) {
103 		/* XCR0 SSE and AVX bits must be set. */
104 		return 0;
105 	}
106 	return 1;
107 }
108 #else
is_avx_supported(void)109 static bool is_avx_supported(void) {
110 	return 0;
111 }
112 #endif
113 
zend_cpu_startup(void)114 void zend_cpu_startup(void)
115 {
116 	if (!cpuinfo.initialized) {
117 		zend_cpu_info ebx;
118 		int max_feature;
119 
120 		cpuinfo.initialized = 1;
121 		__zend_cpuid(0, 0, &cpuinfo);
122 		max_feature = cpuinfo.eax;
123 		if (max_feature == 0) {
124 			return;
125 		}
126 
127 		__zend_cpuid(1, 0, &cpuinfo);
128 
129 		/* for avx2 */
130 		if (max_feature >= 7) {
131 			__zend_cpuid(7, 0, &ebx);
132 			cpuinfo.ebx = ebx.ebx;
133 		} else {
134 			cpuinfo.ebx = 0;
135 		}
136 
137 		if (!is_avx_supported()) {
138 			cpuinfo.edx &= ~ZEND_CPU_FEATURE_AVX;
139 			cpuinfo.ebx &= ~(ZEND_CPU_FEATURE_AVX2 & ~ZEND_CPU_EBX_MASK);
140 		}
141 	}
142 }
143 
zend_cpu_supports(zend_cpu_feature feature)144 ZEND_API int zend_cpu_supports(zend_cpu_feature feature) {
145 	ZEND_ASSERT(cpuinfo.initialized);
146 	if (feature & ZEND_CPU_EDX_MASK) {
147 		return (cpuinfo.edx & (feature & ~ZEND_CPU_EDX_MASK));
148 	} else if (feature & ZEND_CPU_EBX_MASK) {
149 		return (cpuinfo.ebx & (feature & ~ZEND_CPU_EBX_MASK));
150 	} else {
151 		return (cpuinfo.ecx & feature);
152 	}
153 }
154