static void
clear_ldt_entry(uint index)
{
our_modify_ldt_t array;
int ret;
clear_ldt_struct(&array, index);
ret = modify_ldt_syscall(1, (void *)&array, sizeof(array));
ASSERT(ret >= 0);
}
void
tls_thread_free(tls_type_t tls_type, int index)
{
if (tls_type == TLS_TYPE_LDT)
clear_ldt_entry(index);
else if (tls_type == TLS_TYPE_GDT) {
our_modify_ldt_t desc;
clear_ldt_struct(&desc, index);
DEBUG_DECLARE(int res = )
dynamorio_syscall(SYS_set_thread_area, 1, &desc);
ASSERT(res >= 0);
}
/* i#2089: we skip this for non-detach */
void
tls_thread_free(tls_type_t tls_type, int index)
{
/* XXX i#107 (and i#2088): We need to restore the segment base the
* app was using when we detach, instead of just clearing.
*/
if (tls_type == TLS_TYPE_LDT)
clear_ldt_entry(index);
else if (tls_type == TLS_TYPE_GDT) {
our_modify_ldt_t desc;
clear_ldt_struct(&desc, index);
DEBUG_DECLARE(int res =)
dynamorio_syscall(SYS_set_thread_area, 1, &desc);
ASSERT(res >= 0);
}
/* Queries the set of available GDT slots, and initializes:
* - tls_gdt_index
* - gdt_entry_tls_min on ia32
* - lib_tls_gdt_index if using private loader
* GDT slots are initialized with a base and limit of zero. The caller is
* responsible for setting them to a real base.
*/
static void
choose_gdt_slots(os_local_state_t *os_tls)
{
our_modify_ldt_t desc;
int i;
int avail_index[GDT_NUM_TLS_SLOTS];
our_modify_ldt_t clear_desc;
int res;
/* using local static b/c dynamo_initialized is not set for a client thread
* when created in client's dr_init routine
*/
/* FIXME: Could be racy if we have multiple threads initializing during
* startup.
*/
if (tls_global_init)
return;
tls_global_init = true;
/* We don't want to break the assumptions of pthreads or wine,
* so we try to take the last slot. We don't want to hardcode
* the index b/c the kernel will let us clobber entries so we want
* to only pass in -1.
*/
ASSERT(!dynamo_initialized);
ASSERT(tls_gdt_index == -1);
for (i = 0; i < GDT_NUM_TLS_SLOTS; i++)
avail_index[i] = -1;
for (i = 0; i < GDT_NUM_TLS_SLOTS; i++) {
/* We use a base and limit of 0 for testing what's available. */
initialize_ldt_struct(&desc, NULL, 0, -1);
res = dynamorio_syscall(SYS_set_thread_area, 1, &desc);
LOG(GLOBAL, LOG_THREADS, 4,
"%s: set_thread_area -1 => %d res, %d index\n",
__FUNCTION__, res, desc.entry_number);
if (res >= 0) {
/* We assume monotonic increases */
avail_index[i] = desc.entry_number;
ASSERT(avail_index[i] > tls_gdt_index);
tls_gdt_index = desc.entry_number;
} else
break;
}
#ifndef X64
/* In x86-64's ia32 emulation,
* set_thread_area(6 <= entry_number && entry_number <= 8) fails
* with EINVAL (22) because x86-64 only accepts GDT indices 12 to 14
* for TLS entries.
*/
if (tls_gdt_index > (gdt_entry_tls_min + GDT_NUM_TLS_SLOTS))
gdt_entry_tls_min = GDT_ENTRY_TLS_MIN_64; /* The kernel is x64. */
#endif
/* Now give up the earlier slots */
for (i = 0; i < GDT_NUM_TLS_SLOTS; i++) {
if (avail_index[i] > -1 &&
avail_index[i] != tls_gdt_index) {
LOG(GLOBAL, LOG_THREADS, 4,
"clearing set_thread_area index %d\n", avail_index[i]);
clear_ldt_struct(&clear_desc, avail_index[i]);
res = dynamorio_syscall(SYS_set_thread_area, 1, &clear_desc);
ASSERT(res >= 0);
}
}
#ifndef VMX86_SERVER
ASSERT_CURIOSITY(tls_gdt_index ==
(kernel_is_64bit() ? GDT_64BIT : GDT_32BIT));
#endif
#ifdef CLIENT_INTERFACE
if (INTERNAL_OPTION(private_loader) && tls_gdt_index != -1) {
/* Use the app's selector with our own TLS base for libraries. app_fs
* and app_gs are initialized by the caller in os_tls_app_seg_init().
*/
int index = SELECTOR_INDEX(os_tls->app_lib_tls_reg);
if (index == 0) {
/* An index of zero means the app has no TLS (yet), and happens
* during early injection. We use -1 to grab a new entry. When the
* app asks for its first table entry with set_thread_area, we give
* it this one and emulate its usage of the segment.
*/
ASSERT_CURIOSITY(DYNAMO_OPTION(early_inject) && "app has "
"no TLS, but we used non-early injection");
initialize_ldt_struct(&desc, NULL, 0, -1);
res = dynamorio_syscall(SYS_set_thread_area, 1, &desc);
LOG(GLOBAL, LOG_THREADS, 4,
"%s: set_thread_area -1 => %d res, %d index\n",
__FUNCTION__, res, desc.entry_number);
ASSERT(res >= 0);
if (res >= 0) {
return_stolen_lib_tls_gdt = true;
index = desc.entry_number;
}
}
lib_tls_gdt_index = index;
}
#endif
}
