mem: fix undefined behavior in NUMA-aware mapping
[dpdk.git] / lib / librte_eal / linuxapp / eal / eal_cpuflags.c
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 <sys/stat.h>
9 #include <sys/types.h>
10 #include <unistd.h>
11
12 #if defined(__GLIBC__) && defined(__GLIBC_PREREQ)
13 #if __GLIBC_PREREQ(2, 16)
14 #include <sys/auxv.h>
15 #define HAS_AUXV 1
16 #endif
17 #endif
18
19 #include <rte_cpuflags.h>
20
21 #ifndef HAS_AUXV
22 static unsigned long
23 getauxval(unsigned long type __rte_unused)
24 {
25         errno = ENOTSUP;
26         return 0;
27 }
28 #endif
29
30 #ifdef RTE_ARCH_64
31 typedef Elf64_auxv_t Internal_Elfx_auxv_t;
32 #else
33 typedef Elf32_auxv_t Internal_Elfx_auxv_t;
34 #endif
35
36 /**
37  * Provides a method for retrieving values from the auxiliary vector and
38  * possibly running a string comparison.
39  *
40  * @return Always returns a result.  When the result is 0, check errno
41  * to see if an error occurred during processing.
42  */
43 static unsigned long
44 _rte_cpu_getauxval(unsigned long type, const char *str)
45 {
46         unsigned long val;
47
48         errno = 0;
49         val = getauxval(type);
50
51         if (!val && (errno == ENOTSUP || errno == ENOENT)) {
52                 int auxv_fd = open("/proc/self/auxv", O_RDONLY);
53                 Internal_Elfx_auxv_t auxv;
54
55                 if (auxv_fd == -1)
56                         return 0;
57
58                 errno = ENOENT;
59                 while (read(auxv_fd, &auxv, sizeof(auxv)) == sizeof(auxv)) {
60                         if (auxv.a_type == type) {
61                                 errno = 0;
62                                 val = auxv.a_un.a_val;
63                                 if (str)
64                                         val = strcmp((const char *)val, str);
65                                 break;
66                         }
67                 }
68                 close(auxv_fd);
69         }
70
71         return val;
72 }
73
74 unsigned long
75 rte_cpu_getauxval(unsigned long type)
76 {
77         return _rte_cpu_getauxval(type, NULL);
78 }
79
80 int
81 rte_cpu_strcmp_auxval(unsigned long type, const char *str)
82 {
83         return _rte_cpu_getauxval(type, str);
84 }