1 /* 2 * Copyright (c) 2020 Intel Corporation. 3 * 4 * SPDX-License-Identifier: Apache-2.0 5 */ 6 7 #include <kernel_internal.h> 8 #include <zephyr/arch/x86/ia32/arch.h> 9 #include <zephyr/arch/x86/ia32/segmentation.h> 10 11 #define ENTRY_NUM (GS_TLS_SEG >> 3) 12 z_x86_tls_update_gdt(struct k_thread * thread)13void z_x86_tls_update_gdt(struct k_thread *thread) 14 { 15 /* 16 * GS is used for thread local storage to pointer to 17 * the TLS storage area in stack. Here we update one 18 * of the descriptor so GS has the new address. 19 * 20 * The re-loading of descriptor into GS is taken care 21 * of inside the assembly swap code just before 22 * swapping into the new thread. 23 */ 24 25 struct segment_descriptor *sd = &_gdt.entries[ENTRY_NUM]; 26 27 sd->base_low = thread->tls & 0xFFFFU; 28 sd->base_mid = (thread->tls >> 16) & 0xFFU; 29 sd->base_hi = (thread->tls >> 24) & 0xFFU; 30 } 31 32 FUNC_NO_STACK_PROTECTOR z_x86_early_tls_update_gdt(char * stack_ptr)33void z_x86_early_tls_update_gdt(char *stack_ptr) 34 { 35 uintptr_t *self_ptr; 36 uintptr_t tls_seg = GS_TLS_SEG; 37 struct segment_descriptor *sd = &_gdt.entries[ENTRY_NUM]; 38 39 /* 40 * Since we are populating things backwards, store 41 * the pointer to the TLS area at top of stack. 42 */ 43 stack_ptr -= sizeof(uintptr_t); 44 self_ptr = (void *)stack_ptr; 45 *self_ptr = POINTER_TO_UINT(stack_ptr); 46 47 sd->base_low = POINTER_TO_UINT(self_ptr) & 0xFFFFU; 48 sd->base_mid = (POINTER_TO_UINT(self_ptr) >> 16) & 0xFFU; 49 sd->base_hi = (POINTER_TO_UINT(self_ptr) >> 24) & 0xFFU; 50 51 __asm__ volatile( 52 "movl %0, %%eax;\n\t" 53 "movl %%eax, %%gs;\n\t" 54 : 55 : "r"(tls_seg)); 56 } 57
