| // Copyright 2016 The Fuchsia Authors |
| // Copyright (c) 2016 Travis Geiselbrecht |
| // |
| // Use of this source code is governed by a MIT-style |
| // license that can be found in the LICENSE file or at |
| // https://opensource.org/licenses/MIT |
| |
| #include <arch/x86/mp.h> |
| |
| #pragma once |
| |
| __BEGIN_CDECLS |
| |
| static inline struct thread *get_current_thread(void) |
| { |
| /* Read directly from gs, rather than via x86_get_percpu()->current_thread, |
| * so that this is atomic. Otherwise, we could context switch between the |
| * read of percpu from gs and the read of the current_thread pointer, and |
| * discover the current thread on a different CPU */ |
| return (struct thread *)x86_read_gs_offset64(PERCPU_CURRENT_THREAD_OFFSET); |
| } |
| |
| static inline void set_current_thread(struct thread *t) |
| { |
| /* See above for why this is a direct gs write */ |
| x86_write_gs_offset64(PERCPU_CURRENT_THREAD_OFFSET, (uint64_t)t); |
| } |
| |
| __END_CDECLS |
