LXR linux/arch/x86/um/os-Linux/tls.c

   1// SPDX-License-Identifier: GPL-2.0
   2#include <errno.h>
   3#include <linux/unistd.h>
   4
   5#include <sys/ptrace.h>
   6#include <sys/syscall.h>
   7#include <unistd.h>
   8
   9#include <sysdep/tls.h>
  10
  11#ifndef PTRACE_GET_THREAD_AREA
  12#define PTRACE_GET_THREAD_AREA 25
  13#endif
  14
  15#ifndef PTRACE_SET_THREAD_AREA
  16#define PTRACE_SET_THREAD_AREA 26
  17#endif
  18
  19/* Checks whether host supports TLS, and sets *tls_min according to the value
  20 * valid on the host.
  21 * i386 host have it == 6; x86_64 host have it == 12, for i386 emulation. */
  22void check_host_supports_tls(int *supports_tls, int *tls_min)
  23{
  24        /* Values for x86 and x86_64.*/
  25        int val[] = {GDT_ENTRY_TLS_MIN_I386, GDT_ENTRY_TLS_MIN_X86_64};
  26        int i;
  27
  28        for (i = 0; i < ARRAY_SIZE(val); i++) {
  29                user_desc_t info;
  30                info.entry_number = val[i];
  31
  32                if (syscall(__NR_get_thread_area, &info) == 0) {
  33                        *tls_min = val[i];
  34                        *supports_tls = 1;
  35                        return;
  36                } else {
  37                        if (errno == EINVAL)
  38                                continue;
  39                        else if (errno == ENOSYS)
  40                                *supports_tls = 0;
  41                        return;
  42                }
  43        }
  44
  45        *supports_tls = 0;
  46}
  47
  48int os_set_thread_area(user_desc_t *info, int pid)
  49{
  50        int ret;
  51
  52        ret = ptrace(PTRACE_SET_THREAD_AREA, pid, info->entry_number,
  53                     (unsigned long) info);
  54        if (ret < 0)
  55                ret = -errno;
  56        return ret;
  57}
  58
  59int os_get_thread_area(user_desc_t *info, int pid)
  60{
  61        int ret;
  62
  63        ret = ptrace(PTRACE_GET_THREAD_AREA, pid, info->entry_number,
  64                     (unsigned long) info);
  65        if (ret < 0)
  66                ret = -errno;
  67        return ret;
  68}
  69