1#include <errno.h> 2#include <linux/unistd.h> 3 4#include <sys/syscall.h> 5#include <unistd.h> 6 7#include "sysdep/tls.h" 8#include "user.h" 9 10/* Checks whether host supports TLS, and sets *tls_min according to the value 11 * valid on the host. 12 * i386 host have it == 6; x86_64 host have it == 12, for i386 emulation. */ 13void check_host_supports_tls(int *supports_tls, int *tls_min) { 14 /* Values for x86 and x86_64.*/ 15 int val[] = {GDT_ENTRY_TLS_MIN_I386, GDT_ENTRY_TLS_MIN_X86_64}; 16 int i; 17 18 for (i = 0; i < ARRAY_SIZE(val); i++) { 19 user_desc_t info; 20 info.entry_number = val[i]; 21 22 if (syscall(__NR_get_thread_area, &info) == 0) { 23 *tls_min = val[i]; 24 *supports_tls = 1; 25 return; 26 } else { 27 if (errno == EINVAL) 28 continue; 29 else if (errno == ENOSYS) 30 *supports_tls = 0; 31 return; 32 } 33 } 34 35 *supports_tls = 0; 36} 37