source: mainline/uspace/lib/c/arch/amd64/Makefile.common@ 58563585

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since 58563585 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: 1.6 KB
Line 
1#
2# Copyright (c) 2005 Martin Decky
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
29GCC_CFLAGS += -mno-tls-direct-seg-refs -fno-omit-frame-pointer
30CLANG_CFLAGS += -fno-omit-frame-pointer
31
32ENDIANESS = LE
33
34BFD_NAME = elf64-x86-64
35BFD_ARCH = i386:x86-64
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