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1 | /* -*-c-*- |
2 | * | |
3 | * CPU-specific dispatch | |
4 | * | |
5 | * (c) 2015 Straylight/Edgeware | |
6 | */ | |
7 | ||
8 | /*----- Licensing notice --------------------------------------------------* | |
9 | * | |
10 | * This file is part of Catacomb. | |
11 | * | |
12 | * Catacomb is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU Library General Public License as | |
14 | * published by the Free Software Foundation; either version 2 of the | |
15 | * License, or (at your option) any later version. | |
16 | * | |
17 | * Catacomb is distributed in the hope that it will be useful, | |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU Library General Public License for more details. | |
21 | * | |
22 | * You should have received a copy of the GNU Library General Public | |
23 | * License along with Catacomb; if not, write to the Free | |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, | |
25 | * MA 02111-1307, USA. | |
26 | */ | |
27 | ||
28 | /*----- Header files ------------------------------------------------------*/ | |
29 | ||
30 | #include "config.h" | |
31 | ||
32 | #include <ctype.h> | |
33 | #include <stdlib.h> | |
34 | #include <string.h> | |
35 | ||
36 | #include <mLib/macros.h> | |
37 | ||
38 | #include "dispatch.h" | |
39 | ||
40 | /*----- Main code ---------------------------------------------------------*/ | |
41 | ||
42 | #ifdef CPUFAM_X86 | |
43 | ||
44 | #define EFLAGS_ID (1u << 21) | |
45 | #define CPUID1D_SSE2 (1u << 26) | |
acbe16df | 46 | #define CPUID1D_FXSR (1u << 24) |
08e2be29 MW |
47 | |
48 | struct cpuid { unsigned a, b, c, d; }; | |
49 | ||
50 | /* --- @cpuid@ --- * | |
51 | * | |
52 | * Arguments: @struct cpuid *cc@ = where to write the result | |
53 | * @unsigned a, c@ = EAX and ECX registers to set | |
54 | * | |
55 | * Returns: --- | |
56 | * | |
57 | * Use: Minimal C wrapper around the x86 `CPUID' instruction. Checks | |
58 | * that the instruction is actually available before invoking | |
59 | * it; fills the output structure with zero if it's not going to | |
60 | * work. | |
61 | */ | |
62 | ||
63 | #ifdef __GNUC__ | |
64 | static __inline__ unsigned getflags(void) | |
65 | { unsigned f; __asm__ ("pushf; popl %0" : "=g" (f)); return (f); } | |
66 | static __inline__ unsigned setflags(unsigned f) | |
67 | { | |
68 | unsigned ff; | |
69 | __asm__ ("pushf; pushl %1; popf; pushf; popl %0; popf" | |
70 | : "=g" (ff) | |
71 | : "g" (f)); | |
72 | return (ff); | |
73 | } | |
74 | #endif | |
75 | ||
76 | static void cpuid(struct cpuid *cc, unsigned a, unsigned c) | |
77 | { | |
78 | #ifdef __GNUC__ | |
79 | unsigned f; | |
80 | #endif | |
81 | ||
82 | cc->a = cc->b = cc->c = cc->d = 0; | |
83 | ||
84 | #ifdef __GNUC__ | |
85 | /* Stupid dance to detect whether the CPUID instruction is available. */ | |
86 | f = getflags(); | |
87 | if (!(setflags(f | EFLAGS_ID) & EFLAGS_ID)) return; | |
88 | if ( setflags(f & ~EFLAGS_ID) & EFLAGS_ID ) return; | |
89 | setflags(f); | |
90 | ||
91 | /* Alas, EBX is magical in PIC code, so abuse ESI instead. This isn't | |
92 | * pretty, but it works. | |
93 | */ | |
94 | __asm__ ("pushl %%ebx; cpuid; movl %%ebx, %%esi; popl %%ebx" | |
95 | : "=a" (cc->a), "=S" (cc->b), "=c" (cc->c), "=d" (cc->d) | |
96 | : "a" (a) , "c" (c)); | |
97 | #endif | |
98 | } | |
99 | ||
100 | static unsigned cpuid_maxleaf(void) | |
101 | { struct cpuid c; cpuid(&c, 0, 0); return (c.a); } | |
102 | ||
103 | static int cpuid_features_p(unsigned dbits, unsigned cbits) | |
104 | { | |
105 | struct cpuid c; | |
106 | if (cpuid_maxleaf() < 1) return (0); | |
107 | cpuid(&c, 1, 0); | |
108 | return ((c.d & dbits) == dbits && (c.c & cbits) == cbits); | |
109 | } | |
110 | ||
acbe16df MW |
111 | static int xmm_registers_available_p(void) |
112 | { | |
113 | #ifdef __GNUC__ | |
114 | unsigned f; | |
115 | /* This hack is by Agner Fog. Use FXSAVE/FXRSTOR to figure out whether the | |
116 | * XMM registers are actually alive. | |
117 | */ | |
118 | if (!cpuid_features_p(CPUID1D_FXSR, 0)) return (0); | |
119 | __asm__ ("movl %%esp, %%edx; subl $512, %%esp; andl $~15, %%esp\n" | |
120 | "fxsave (%%esp)\n" | |
121 | "movl 160(%%esp), %%eax; xorl $0xaaaa5555, 160(%%esp)\n" | |
122 | "fxrstor (%%esp); fxsave (%%esp)\n" | |
123 | "movl 160(%%esp), %%ecx; movl %%eax, 160(%%esp)\n" | |
124 | "fxrstor (%%esp); movl %%edx, %%esp\n" | |
125 | "xorl %%ecx, %%eax" | |
126 | : "=a" (f) | |
127 | : /* no inputs */ | |
128 | : "%ecx", "%edx"); | |
129 | return (f); | |
130 | #else | |
131 | return (0); | |
132 | #endif | |
133 | } | |
134 | ||
08e2be29 MW |
135 | #endif |
136 | ||
137 | /* --- @check_env@ --- * | |
138 | * | |
139 | * Arguments: @const char *ftok@ = feature token | |
140 | * | |
141 | * Returns: Zero if the feature is forced off; positive if it's forced | |
142 | * on; negative if the user hasn't decided. | |
143 | * | |
144 | * Use: Checks the environment variable `CATACOMB_CPUFEAT' for the | |
145 | * feature token @ftok@. The variable, if it exists, should be | |
146 | * a space-separated sequence of `+tok' and `-tok' items. These | |
147 | * tokens may end in `*', which matches any suffix. | |
148 | */ | |
149 | ||
150 | static int IGNORABLE check_env(const char *ftok) | |
151 | { | |
152 | const char *p, *q, *pp; | |
153 | int d; | |
154 | ||
155 | p = getenv("CATACOMB_CPUFEAT"); | |
156 | if (!p) return (-1); | |
157 | ||
158 | for (;;) { | |
159 | while (isspace((unsigned char)*p)) p++; | |
160 | if (!*p) return (-1); | |
161 | switch (*p) { | |
162 | case '+': d = +1; p++; break; | |
163 | case '-': d = 0; p++; break; | |
164 | default: d = -1; break; | |
165 | } | |
166 | for (q = p; *q && !isspace((unsigned char)*q); q++); | |
167 | if (d >= 0) { | |
168 | for (pp = ftok; p < q && *pp && *p == *pp; p++, pp++); | |
169 | if ((p == q && !*pp) || (*p == '*' && p + 1 == q)) return (d); | |
170 | } | |
171 | p = q; | |
172 | } | |
173 | return (-1); | |
174 | } | |
175 | ||
176 | /* --- @cpu_feature_p@ --- * | |
177 | * | |
178 | * Arguments: @unsigned feat@ = a @CPUFEAT_...@ code | |
179 | * | |
180 | * Returns: Nonzero if the feature is available. | |
181 | */ | |
182 | ||
183 | #include <stdio.h> | |
184 | ||
185 | int cpu_feature_p(int feat) | |
186 | { | |
187 | int IGNORABLE f; | |
188 | IGNORE(f); | |
189 | #define CHECK_ENV(ftok) \ | |
190 | do { if ((f = check_env(ftok)) >= 0) return (f); } while (0) | |
191 | ||
192 | switch (feat) { | |
193 | #ifdef CPUFAM_X86 | |
194 | case CPUFEAT_X86_SSE2: { | |
195 | CHECK_ENV("x86:sse2"); | |
acbe16df MW |
196 | return (xmm_registers_available_p() && |
197 | cpuid_features_p(CPUID1D_SSE2, 0)); | |
08e2be29 MW |
198 | } |
199 | #endif | |
200 | default: | |
201 | return (0); | |
202 | } | |
203 | #undef CHECK_ENV | |
204 | } | |
205 | ||
206 | /*----- That's all, folks -------------------------------------------------*/ |