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 }