1 /* SPDX-License-Identifier: BSD-3-Clause
2 * Copyright 2018 Red Hat, Inc.
3 */
4
5 #include <elf.h>
6 #include <fcntl.h>
7 #include <string.h>
8 #include <unistd.h>
9
10 #if defined(__GLIBC__) && defined(__GLIBC_PREREQ)
11 #if __GLIBC_PREREQ(2, 16)
12 #include <sys/auxv.h>
13 #define HAS_AUXV 1
14 #endif
15 #endif
16
17 #include <rte_cpuflags.h>
18
19 #ifndef HAS_AUXV
20 static unsigned long
getauxval(unsigned long type __rte_unused)21 getauxval(unsigned long type __rte_unused)
22 {
23 errno = ENOTSUP;
24 return 0;
25 }
26 #endif
27
28 #ifdef RTE_ARCH_64
29 typedef Elf64_auxv_t Internal_Elfx_auxv_t;
30 #else
31 typedef Elf32_auxv_t Internal_Elfx_auxv_t;
32 #endif
33
34 /**
35 * Provides a method for retrieving values from the auxiliary vector and
36 * possibly running a string comparison.
37 *
38 * @return Always returns a result. When the result is 0, check errno
39 * to see if an error occurred during processing.
40 */
41 static unsigned long
_rte_cpu_getauxval(unsigned long type,const char * str)42 _rte_cpu_getauxval(unsigned long type, const char *str)
43 {
44 unsigned long val;
45
46 errno = 0;
47 val = getauxval(type);
48
49 if (!val && (errno == ENOTSUP || errno == ENOENT)) {
50 int auxv_fd = open("/proc/self/auxv", O_RDONLY);
51 Internal_Elfx_auxv_t auxv;
52
53 if (auxv_fd == -1)
54 return 0;
55
56 errno = ENOENT;
57 while (read(auxv_fd, &auxv, sizeof(auxv)) == sizeof(auxv)) {
58 if (auxv.a_type == type) {
59 errno = 0;
60 val = auxv.a_un.a_val;
61 if (str)
62 val = strcmp((const char *)val, str);
63 break;
64 }
65 }
66 close(auxv_fd);
67 }
68
69 return val;
70 }
71
72 unsigned long
rte_cpu_getauxval(unsigned long type)73 rte_cpu_getauxval(unsigned long type)
74 {
75 return _rte_cpu_getauxval(type, NULL);
76 }
77
78 int
rte_cpu_strcmp_auxval(unsigned long type,const char * str)79 rte_cpu_strcmp_auxval(unsigned long type, const char *str)
80 {
81 return _rte_cpu_getauxval(type, str);
82 }
83