source: mainline/kernel/arch/amd64/src/proc/scheduler.c@ 525c5ac

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since 525c5ac was 1a5eca4, checked in by Jakub Jermar <jakub@…>, 9 years ago

amd64: Make TLS settable from uspace

The TLS document[1] mandates that %fs[0] is the thread pointer on amd64.
That is good as it allows userspace-only TLS management for fibrils:
fibril_save/restore() simply manipulate the thread pointer in %fs:0 and
don't need to ask the kernel to modify %fs's base. The kernel treats
%fs:0 as another preserved register and preserves it across context
switches. GCC gets in the way a little bit because it by default assumes
that TLS is accessible from negative %fs offsets (which would
necessitate a kernel-assisted solution). Fortunately, there is a GCC
option to suppress this assumption.

  • Introduce the concept of virtual registers, with VREG_TP (thread pointer) being the first of them
  • Preserve VREG_TP in context_save/restore()
  • Stop using sys_tls_set() in favour of using %fs:0 as the thread pointer
  • Make GCC generate code that always goes through %gs:0 to access TLS
  • Introduce kseg: a per-CPU area accessible from GS_KERNEL that holds the kernel stack, kernel FS base and a scratch space for syscall and int handlers to use

[1] Drepper, U.: ELF Handling For Thread-Local Storage
  • Property mode set to 100644
File size: 2.2 KB
Line 
1/*
2 * Copyright (c) 2005 Ondrej Palkovsky
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/** @addtogroup amd64proc
30 * @{
31 */
32/** @file
33 */
34
35#include <proc/scheduler.h>
36#include <cpu.h>
37#include <proc/task.h>
38#include <proc/thread.h>
39#include <arch.h>
40#include <arch/asm.h>
41#include <print.h>
42#include <arch/pm.h>
43#include <arch/ddi/ddi.h>
44#include <arch/kseg_struct.h>
45
46/** Perform amd64 specific tasks needed before the new task is run.
47 *
48 * Interrupts are disabled.
49 */
50void before_task_runs_arch(void)
51{
52 io_perm_bitmap_install();
53}
54
55/** Perform amd64 specific tasks needed before the new thread is scheduled. */
56void before_thread_runs_arch(void)
57{
58 CPU->arch.tss->rsp0 = (uintptr_t) &THREAD->kstack[STACK_SIZE];
59
60 kseg_t *kseg = (kseg_t *) read_msr(AMD_MSR_GS_KERNEL);
61 kseg->kstack_rsp = THREAD->arch.kstack_rsp;
62}
63
64void after_thread_ran_arch(void)
65{
66}
67
68/** @}
69 */
Note: See TracBrowser for help on using the repository browser.