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| author | H.J. Lu <hjl.tools@gmail.com> | 2017-08-08 08:41:08 -0700 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2017-08-08 08:43:15 -0700 |
| commit | 086df229eef36041cae4a633c6fde6150f18d75e (patch) | |
| tree | 47dff30e27b32d6a0b472bfe76e36aa08bf7baa7 /elf | |
| parent | fc5ad7024c620cdfe9b76e94638aac83b99c5bf8 (diff) | |
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i386: Add <startup.h> [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 <startup.h> 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 <startup.h> first.
(__libc_setup_tls): Call _startup_fatal instead of __libc_fatal.
* elf/dl-tunables.c: Include <startup.h> 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.
Diffstat (limited to 'elf')
| -rw-r--r-- | elf/dl-tunables.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c index 231fb8ca93..b964a09413 100644 --- a/elf/dl-tunables.c +++ b/elf/dl-tunables.c @@ -18,6 +18,7 @@ License along with the GNU C Library; if not, see <http://www.gnu.org/licenses/>. */ +#include <startup.h> #include <stdint.h> #include <stdbool.h> #include <unistd.h> |