glibc/sysdeps/powerpc/dl-tls.c

/* Thread-local storage handling in the ELF dynamic linker.  PowerPC version.
   Copyright (C) 2009-2015 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include "elf/dl-tls.c"

#ifdef SHARED
strong_alias(__tls_get_addr, __tls_get_addr_opt)
#endif
powerpc __tls_get_addr call optimization This patch is glibc support for a PowerPC TLS optimization, inspired by Alexandre Oliva's TLS optimization for other processors, http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt In essence, this optimization uses a zero module id in the tls_index GOT entry to indicate that a TLS variable is allocated space in the static TLS area. A special plt call linker stub for __tls_get_addr checks for such a tls_index and if found, returns the offset immediately. The linker communicates the fact that the special __tls_get_addr stub is used by setting a bit in the dynamic tag DT_PPC64_OPT/DT_PPC_OPT. glibc communicates to the linker that this optimization is available by the presence of __tls_get_addr_opt. tst-tlsmod2.so is built with -Wl,--no-tls-get-addr-optimize for tst-tls-dlinfo, which otherwise would fail since it tests that no static tls is allocated. The ld option --no-tls-get-addr-optimize has been available since binutils-2.20 so doesn't need a configure test. * NEWS: Advertise TLS optimization. * elf/elf.h (R_PPC_TLSGD, R_PPC_TLSLD, DT_PPC_OPT, PPC_OPT_TLS): Define. (DT_PPC_NUM): Increment. * elf/dynamic-link.h (HAVE_STATIC_TLS): Define. (CHECK_STATIC_TLS): Use here. * sysdeps/powerpc/powerpc32/dl-machine.h (elf_machine_rela): Optimize TLS descriptors. * sysdeps/powerpc/powerpc64/dl-machine.h (elf_machine_rela): Likewise. * sysdeps/powerpc/dl-tls.c: New file. * sysdeps/powerpc/Versions: Add __tls_get_addr_opt. * sysdeps/powerpc/tst-tlsopt-powerpc.c: New tls test. * sysdeps/unix/sysv/linux/powerpc/Makefile: Add new test. Build tst-tlsmod2.so with --no-tls-get-addr-optimize. * sysdeps/unix/sysv/linux/powerpc/powerpc32/ld.abilist: Update. * sysdeps/unix/sysv/linux/powerpc/powerpc64/ld.abilist: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/ld-le.abilist: Likewise. 2015-03-25 05:23:47 +00:00			`/* Thread-local storage handling in the ELF dynamic linker. PowerPC version.`
			`Copyright (C) 2009-2015 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, write to the Free`
			`Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA`
			`02111-1307 USA. */`

			`#include "elf/dl-tls.c"`

			`#ifdef SHARED`
			`strong_alias(__tls_get_addr, __tls_get_addr_opt)`
			`#endif`