zephyr/arch/x86/core/tls.c

46 lines
1.1 KiB
C

/*
* Copyright (c) 2020 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <kernel.h>
#include <kernel_structs.h>
#include <kernel_internal.h>
#include <kernel_tls.h>
#include <sys/util.h>
size_t arch_tls_stack_setup(struct k_thread *new_thread, char *stack_ptr)
{
/*
* TLS area for x86 and x86_64 has the data/bss first,
* then a pointer pointing to itself. The address to
* this pointer needs to be stored in register GS (x86)
* or FS (x86_64). GCC generates code which reads this
* pointer and offsets from this pointer are used to
* access data.
*/
uintptr_t *self_ptr;
/*
* Since we are populating things backwards, store
* the pointer to the TLS area at top of stack.
*/
stack_ptr -= sizeof(uintptr_t);
self_ptr = (void *)stack_ptr;
*self_ptr = POINTER_TO_UINT(stack_ptr);
/*
* Set thread TLS pointer as this is used to populate
* FS/GS at context switch.
*/
new_thread->tls = POINTER_TO_UINT(self_ptr);
/* Setup the TLS data */
stack_ptr -= z_tls_data_size();
z_tls_copy(stack_ptr);
return (z_tls_data_size() + sizeof(uintptr_t));
}