lib/eal/linux/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 <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
  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
  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
  73 rte_cpu_getauxval(unsigned long type)
  74 {
  75         return _rte_cpu_getauxval(type, NULL);
  76 }
  77
  78 int
  79 rte_cpu_strcmp_auxval(unsigned long type, const char *str)
  80 {
  81         return _rte_cpu_getauxval(type, str);
  82 }