The syscall wrappers had to save and restore the syscall parameter
values and return value when calling the functions to enable/disable
cancellation were called. Not anymore. The called functions are
special and don't modify any unexpected registers.
SSE registers are used for passing parameters and must be preserved
in runtime relocations. This is inside ld.so enforced through the
tests in tst-xmmymm.sh. But the malloc routines used after startup
come from libc.so and can be arbitrarily complex. It's overkill
to save the SSE registers all the time because of that. These calls
are rare. Instead we save them on demand. The new infrastructure
put in place in this patch makes this possible and efficient.
private futexes are available.
* allocatestack.c (allocate_stack): Copy private_futex field from
current thread into the new stack.
* sysdeps/unix/sysv/linux/x86_64/libc-lowlevellock.S: Use private
futexes if they are available.
* sysdeps/unix/sysv/linux/i386/i486/libc-lowlevellock.S: Likewise
* sysdeps/unix/sysv/linux/x86_64/lowlevellock.S: Adjust so that change
in libc-lowlevellock.S allow using private futexes.
* sysdeps/unix/sysv/linux/i386/i486/lowlevellock.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Define
FUTEX_PRIVATE_FLAG.
* sysdeps/unix/sysv/linux/i386/lowlevellock.h: Likewise.
* sysdeps/unix/sysv/linux/x86_64/pthread_once.S: Use private futexes
if they are available.
* sysdeps/unix/sysv/linux/i386/pthread_once.S: Likewise.
* sysdeps/x86_64/tcb-offsets.sym: Add PRIVATE_FUTEX.
* sysdeps/i386/tcb-offsets.sym: Likewise.
* sysdeps/x86_64/tls.h (tcbhead_t): Add private_futex field.
* sysdeps/i386/tls.h (tcbhead_t): Likewise.
* sysdeps/unix/sysv/linux/sched_getcpu.c: New file.
* sysdeps/unix/sysv/linux/x86_64/sched_getcpu.S: New file.
* sysdeps/unix/sysv/linux/Versions: Export sched_getcpu for
GLIBC_2.6.
* elf/rtld.c: Define __pointer_chk_guard_local and if necessary
__pointer_chk_guard.
(_rtld_global_ro): Initialize _dl_pointer_guard.
(dl_main): Initialize __pointer_chk_guard_local and either
__pointer_chk_guard or TLS value if necessary.
(process_envvars): Recognize and handle LD_POINTER_GUARD.
* sysdeps/generic/ldsodefs.h (rtld_global_ro): Add _dl_pointer_guard.
* sysdeps/i386/__longjmp.S: Use PTR_DEMANGLE for PC if defined.
* sysdeps/x86_64/__longjmp.S: Likewise.
* sysdeps/i386/bsd-_setjmp.S: Use PTR_MANGLE for PC if defined.
* sysdeps/i386/bsd-_setjmp.S: Likewise.
* sysdeps/i386/setjmp.S: Likewise.
[IS_IN_rtld]: Avoid call to __sigjmp_save.
* sysdeps/i386/setjmp.S: Likewise.
* sysdeps/unix/sysv/linux/i386/sysdep.h: Define PTR_MANGLE and
PTR_DEMANGLE.
* sysdeps/unix/sysv/linux/x86_64/sysdep.h: Likewise.
* sysdeps/i386/elf/setjmp.S: Removed.
* sysdeps/i386/elf/bsd-setjmp.S: Removed.
