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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> | |
fac645f7 MW |
33 | #include <stdarg.h> |
34 | #include <stdio.h> | |
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35 | #include <stdlib.h> |
36 | #include <string.h> | |
37 | ||
38 | #include <mLib/macros.h> | |
39 | ||
40 | #include "dispatch.h" | |
41 | ||
d26ad211 | 42 | /*----- Intel x86/AMD64 feature probing -----------------------------------*/ |
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43 | |
44 | #ifdef CPUFAM_X86 | |
45 | ||
7680f863 MW |
46 | # define EFLAGS_ID (1u << 21) |
47 | # define CPUID1D_SSE2 (1u << 26) | |
48 | # define CPUID1D_FXSR (1u << 24) | |
49 | # define CPUID1C_AESNI (1u << 25) | |
08e2be29 MW |
50 | |
51 | struct cpuid { unsigned a, b, c, d; }; | |
52 | ||
53 | /* --- @cpuid@ --- * | |
54 | * | |
55 | * Arguments: @struct cpuid *cc@ = where to write the result | |
56 | * @unsigned a, c@ = EAX and ECX registers to set | |
57 | * | |
58 | * Returns: --- | |
59 | * | |
60 | * Use: Minimal C wrapper around the x86 `CPUID' instruction. Checks | |
61 | * that the instruction is actually available before invoking | |
62 | * it; fills the output structure with zero if it's not going to | |
63 | * work. | |
64 | */ | |
65 | ||
66 | #ifdef __GNUC__ | |
67 | static __inline__ unsigned getflags(void) | |
68 | { unsigned f; __asm__ ("pushf; popl %0" : "=g" (f)); return (f); } | |
69 | static __inline__ unsigned setflags(unsigned f) | |
70 | { | |
71 | unsigned ff; | |
72 | __asm__ ("pushf; pushl %1; popf; pushf; popl %0; popf" | |
73 | : "=g" (ff) | |
74 | : "g" (f)); | |
75 | return (ff); | |
76 | } | |
77 | #endif | |
78 | ||
79 | static void cpuid(struct cpuid *cc, unsigned a, unsigned c) | |
80 | { | |
81 | #ifdef __GNUC__ | |
82 | unsigned f; | |
83 | #endif | |
84 | ||
85 | cc->a = cc->b = cc->c = cc->d = 0; | |
86 | ||
87 | #ifdef __GNUC__ | |
88 | /* Stupid dance to detect whether the CPUID instruction is available. */ | |
89 | f = getflags(); | |
fac645f7 MW |
90 | if (!(setflags(f | EFLAGS_ID) & EFLAGS_ID) || |
91 | setflags(f & ~EFLAGS_ID) & EFLAGS_ID) { | |
92 | dispatch_debug("CPUID instruction not available"); | |
93 | return; | |
94 | } | |
08e2be29 MW |
95 | setflags(f); |
96 | ||
97 | /* Alas, EBX is magical in PIC code, so abuse ESI instead. This isn't | |
98 | * pretty, but it works. | |
99 | */ | |
100 | __asm__ ("pushl %%ebx; cpuid; movl %%ebx, %%esi; popl %%ebx" | |
101 | : "=a" (cc->a), "=S" (cc->b), "=c" (cc->c), "=d" (cc->d) | |
102 | : "a" (a) , "c" (c)); | |
fac645f7 MW |
103 | #else |
104 | dispatch_debug("GNU inline assembler not available; can't CPUID"); | |
08e2be29 MW |
105 | #endif |
106 | } | |
107 | ||
108 | static unsigned cpuid_maxleaf(void) | |
109 | { struct cpuid c; cpuid(&c, 0, 0); return (c.a); } | |
110 | ||
11b17977 MW |
111 | /* --- @cpuid_features_p@ --- * |
112 | * | |
113 | * Arguments: @unsigned dbits@ = bits to check in EDX | |
114 | * @unsigned cbits@ = bits to check in ECX | |
115 | * | |
116 | * Returns: Nonzero if all the requested bits are set in the CPUID result | |
117 | * on leaf 1. | |
118 | */ | |
119 | ||
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120 | static int cpuid_features_p(unsigned dbits, unsigned cbits) |
121 | { | |
122 | struct cpuid c; | |
123 | if (cpuid_maxleaf() < 1) return (0); | |
124 | cpuid(&c, 1, 0); | |
125 | return ((c.d & dbits) == dbits && (c.c & cbits) == cbits); | |
126 | } | |
127 | ||
11b17977 MW |
128 | /* --- @xmm_registers_available_p@ --- * |
129 | * | |
130 | * Arguments: --- | |
131 | * | |
132 | * Returns: Nonzero if the operating system has made the XMM registers | |
133 | * available for use. | |
134 | */ | |
135 | ||
acbe16df MW |
136 | static int xmm_registers_available_p(void) |
137 | { | |
138 | #ifdef __GNUC__ | |
139 | unsigned f; | |
140 | /* This hack is by Agner Fog. Use FXSAVE/FXRSTOR to figure out whether the | |
141 | * XMM registers are actually alive. | |
142 | */ | |
143 | if (!cpuid_features_p(CPUID1D_FXSR, 0)) return (0); | |
144 | __asm__ ("movl %%esp, %%edx; subl $512, %%esp; andl $~15, %%esp\n" | |
145 | "fxsave (%%esp)\n" | |
146 | "movl 160(%%esp), %%eax; xorl $0xaaaa5555, 160(%%esp)\n" | |
147 | "fxrstor (%%esp); fxsave (%%esp)\n" | |
148 | "movl 160(%%esp), %%ecx; movl %%eax, 160(%%esp)\n" | |
149 | "fxrstor (%%esp); movl %%edx, %%esp\n" | |
150 | "xorl %%ecx, %%eax" | |
151 | : "=a" (f) | |
152 | : /* no inputs */ | |
153 | : "%ecx", "%edx"); | |
154 | return (f); | |
155 | #else | |
fac645f7 | 156 | dispatch_debug("GNU inline assembler not available; can't check for XMM"); |
acbe16df MW |
157 | return (0); |
158 | #endif | |
159 | } | |
160 | ||
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161 | #endif |
162 | ||
d26ad211 MW |
163 | /*----- External interface ------------------------------------------------*/ |
164 | ||
fac645f7 MW |
165 | /* --- @dispatch_debug@ --- * |
166 | * | |
167 | * Arguments: @const char *fmt@ = a format string | |
168 | * @...@ = additional arguments | |
169 | * | |
170 | * Returns: --- | |
171 | * | |
172 | * Use: Writes a formatted message to standard output if dispatch | |
173 | * debugging is enabled. | |
174 | */ | |
175 | ||
176 | void dispatch_debug(const char *fmt, ...) | |
177 | { | |
178 | va_list ap; | |
179 | const char *e = getenv("CATACOMB_CPUDISPATCH_DEBUG"); | |
180 | ||
181 | if (e && *e != 'n' && *e != '0') { | |
182 | va_start(ap, fmt); | |
183 | fputs("Catacomb CPUDISPATCH: ", stderr); | |
184 | vfprintf(stderr, fmt, ap); | |
185 | fputc('\n', stderr); | |
186 | va_end(ap); | |
187 | } | |
188 | } | |
189 | ||
08e2be29 MW |
190 | /* --- @check_env@ --- * |
191 | * | |
192 | * Arguments: @const char *ftok@ = feature token | |
193 | * | |
194 | * Returns: Zero if the feature is forced off; positive if it's forced | |
195 | * on; negative if the user hasn't decided. | |
196 | * | |
197 | * Use: Checks the environment variable `CATACOMB_CPUFEAT' for the | |
198 | * feature token @ftok@. The variable, if it exists, should be | |
199 | * a space-separated sequence of `+tok' and `-tok' items. These | |
200 | * tokens may end in `*', which matches any suffix. | |
201 | */ | |
202 | ||
203 | static int IGNORABLE check_env(const char *ftok) | |
204 | { | |
205 | const char *p, *q, *pp; | |
206 | int d; | |
207 | ||
208 | p = getenv("CATACOMB_CPUFEAT"); | |
209 | if (!p) return (-1); | |
210 | ||
211 | for (;;) { | |
212 | while (isspace((unsigned char)*p)) p++; | |
213 | if (!*p) return (-1); | |
214 | switch (*p) { | |
215 | case '+': d = +1; p++; break; | |
216 | case '-': d = 0; p++; break; | |
217 | default: d = -1; break; | |
218 | } | |
219 | for (q = p; *q && !isspace((unsigned char)*q); q++); | |
220 | if (d >= 0) { | |
221 | for (pp = ftok; p < q && *pp && *p == *pp; p++, pp++); | |
222 | if ((p == q && !*pp) || (*p == '*' && p + 1 == q)) return (d); | |
223 | } | |
224 | p = q; | |
225 | } | |
226 | return (-1); | |
227 | } | |
228 | ||
229 | /* --- @cpu_feature_p@ --- * | |
230 | * | |
231 | * Arguments: @unsigned feat@ = a @CPUFEAT_...@ code | |
232 | * | |
233 | * Returns: Nonzero if the feature is available. | |
234 | */ | |
235 | ||
236 | #include <stdio.h> | |
237 | ||
fac645f7 MW |
238 | static int IGNORABLE |
239 | feat_debug(const char *ftok, const char *check, int verdict) | |
240 | { | |
241 | if (verdict >= 0) { | |
242 | dispatch_debug("feature `%s': %s -> %s", ftok, check, | |
243 | verdict ? "available" : "absent"); | |
244 | } | |
245 | return (verdict); | |
246 | } | |
247 | ||
08e2be29 MW |
248 | int cpu_feature_p(int feat) |
249 | { | |
250 | int IGNORABLE f; | |
251 | IGNORE(f); | |
fac645f7 MW |
252 | #define CASE_CPUFEAT(feat, ftok, cond) case CPUFEAT_##feat: \ |
253 | if ((f = feat_debug(ftok, "environment override", \ | |
254 | check_env(ftok))) >= 0) \ | |
255 | return (f); \ | |
256 | else \ | |
257 | return (feat_debug(ftok, "runtime probe", cond)); | |
08e2be29 MW |
258 | |
259 | switch (feat) { | |
260 | #ifdef CPUFAM_X86 | |
fac645f7 MW |
261 | CASE_CPUFEAT(X86_SSE2, "x86:sse2", |
262 | xmm_registers_available_p() && | |
263 | cpuid_features_p(CPUID1D_SSE2, 0)); | |
264 | CASE_CPUFEAT(X86_AESNI, "x86:aesni", | |
265 | xmm_registers_available_p() && | |
266 | cpuid_features_p(CPUID1D_SSE2, CPUID1C_AESNI)); | |
08e2be29 MW |
267 | #endif |
268 | default: | |
fac645f7 | 269 | dispatch_debug("denying unknown feature %d", feat); |
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270 | return (0); |
271 | } | |
fac645f7 | 272 | #undef CASE_CPUFEAT |
08e2be29 MW |
273 | } |
274 | ||
275 | /*----- That's all, folks -------------------------------------------------*/ |