1 /**
2 * \file
3 * \brief CPU related functions
4 *
5 * \author Frank Mehnert <fm3@os.inf.tu-dresden.de> */
6
7 /*
8 * (c) 2004-2009 Author(s)
9 * economic rights: Technische Universität Dresden (Germany)
10 * This file is part of TUD:OS and distributed under the terms of the
11 * GNU Lesser General Public License 2.1.
12 * Please see the COPYING-LGPL-2.1 file for details.
13 */
14
15 #ifndef __L4_UTIL_CPU_H
16 #define __L4_UTIL_CPU_H
17
18 #include <l4/sys/compiler.h>
19
20 EXTERN_C_BEGIN
21
22 /**
23 * \defgroup l4util_cpu CPU related functions
24 * \ingroup l4util_api
25 */
26 /*@{*/
27
28 /**
29 * Check whether the CPU supports the "cpuid" instruction.
30 *
31 * \return 1 if it has, 0 if it has not
32 */
33 L4_INLINE int l4util_cpu_has_cpuid(void);
34
35 /**
36 * Returns the CPU capabilities if the "cpuid" instruction is available.
37 *
38 * \return CPU capabilities if the "cpuid" instruction is available,
39 * 0 if the "cpuid" instruction is not supported.
40 */
41 L4_INLINE unsigned int l4util_cpu_capabilities(void);
42
43 /**
44 * Returns the CPU capabilities.
45 *
46 * \return CPU capabilities.
47 */
48 L4_INLINE unsigned int l4util_cpu_capabilities_nocheck(void);
49
50 /**
51 * Generic CPUID access function.
52 */
53 L4_INLINE void
54 l4util_cpu_cpuid(unsigned long mode,
55 unsigned long *eax, unsigned long *ebx,
56 unsigned long *ecx, unsigned long *edx);
57
58 /*@}*/
59 static inline void
l4util_cpu_pause(void)60 l4util_cpu_pause(void)
61 {
62 __asm__ __volatile__ ("rep; nop");
63 }
64
65 L4_INLINE int
l4util_cpu_has_cpuid(void)66 l4util_cpu_has_cpuid(void)
67 {
68 unsigned long eax;
69
70 asm volatile("pushl %%ebx \t\n"
71 "pushfl \t\n"
72 "popl %%eax \t\n" /* get eflags */
73 "movl %%eax, %%ebx \t\n" /* save it */
74 "xorl $0x200000, %%eax \t\n" /* toggle ID bit */
75 "pushl %%eax \t\n"
76 "popfl \t\n" /* set again */
77 "pushfl \t\n"
78 "popl %%eax \t\n" /* get it again */
79 "xorl %%ebx, %%eax \t\n"
80 "pushl %%ebx \t\n"
81 "popfl \t\n" /* restore saved flags */
82 "popl %%ebx \t\n"
83 : "=a" (eax)
84 : /* no input */
85 );
86
87 return eax & 0x200000;
88 }
89
90 L4_INLINE void
l4util_cpu_cpuid(unsigned long mode,unsigned long * eax,unsigned long * ebx,unsigned long * ecx,unsigned long * edx)91 l4util_cpu_cpuid(unsigned long mode,
92 unsigned long *eax, unsigned long *ebx,
93 unsigned long *ecx, unsigned long *edx)
94 {
95 asm volatile("pushl %%ebx \t\n"
96 "cpuid \t\n"
97 "mov %%ebx, %%esi \t\n"
98 "popl %%ebx \t\n"
99 : "=a" (*eax),
100 "=S" (*ebx),
101 "=c" (*ecx),
102 "=d" (*edx)
103 : "a" (mode));
104 }
105
106 L4_INLINE unsigned int
l4util_cpu_capabilities_nocheck(void)107 l4util_cpu_capabilities_nocheck(void)
108 {
109 unsigned long dummy, capability;
110
111 /* get CPU capabilities */
112 l4util_cpu_cpuid(1, &dummy, &dummy, &dummy, &capability);
113
114 return capability;
115 }
116
117 L4_INLINE unsigned int
l4util_cpu_capabilities(void)118 l4util_cpu_capabilities(void)
119 {
120 if (!l4util_cpu_has_cpuid())
121 return 0; /* CPU has not cpuid instruction */
122
123 return l4util_cpu_capabilities_nocheck();
124 }
125
126 EXTERN_C_END
127
128 #endif
129
130