From 086df229eef36041cae4a633c6fde6150f18d75e Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Tue, 8 Aug 2017 08:41:08 -0700 Subject: i386: Add [BZ #21913] On Linux/i386, there are 3 ways to make a system call: 1. call *%gs:SYSINFO_OFFSET. This requires TLS initialization. 2. call *_dl_sysinfo. This requires relocation of _dl_sysinfo. 3. int $0x80. This is slower than #2 and #3, but works everywhere. When an object file is compiled with PIC, #1 is prefered since it is faster than #3 and doesn't require relocation of _dl_sysinfo. For dynamic executables, ld.so initializes TLS. However, for static executables, before TLS is initialized by __libc_setup_tls, #3 should be used for system calls. This patch adds which defines _startup_fatal and defaults it to __libc_fatal. It replaces __libc_fatal with _startup_fatal in static executables where it is called before __libc_setup_tls is called. This header file is included in all files containing functions which are called before __libc_setup_tls is called. On Linux/i386, when PIE is enabled by default, _startup_fatal is turned into ABORT_INSTRUCTION and I386_USE_SYSENTER is defined to 0 so that "int $0x80" is used for system calls before __libc_setup_tls is called. Tested on i686 and x86-64. Without this patch, all statically-linked tests will fail on i686 when the compiler defaults to -fPIE. [BZ #21913] * csu/libc-tls.c: Include first. (__libc_setup_tls): Call _startup_fatal instead of __libc_fatal. * elf/dl-tunables.c: Include first. * include/libc-symbols.h (BUILD_PIE_DEFAULT): New. * sysdeps/generic/startup.h: New file. * sysdeps/unix/sysv/linux/i386/startup.h: Likewise. * sysdeps/unix/sysv/linux/i386/brk.c [BUILD_PIE_DEFAULT != 0] (I386_USE_SYSENTER): New. Defined to 0. --- sysdeps/generic/startup.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) create mode 100644 sysdeps/generic/startup.h (limited to 'sysdeps/generic/startup.h') diff --git a/sysdeps/generic/startup.h b/sysdeps/generic/startup.h new file mode 100644 index 0000000..a961e27 --- /dev/null +++ b/sysdeps/generic/startup.h @@ -0,0 +1,23 @@ +/* Generic definitions of functions used by static libc main startup. + Copyright (C) 2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +/* Targets should override this file if the default definitions below + will not work correctly very early before TLS is initialized. */ + +/* Use macro instead of inline function to avoid including . */ +#define _startup_fatal(message) __libc_fatal ((message)) -- cgit v1.1