Patchwork [3/3] arm-linux: Add libitm support.

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Submitter Richard Henderson
Date Dec. 10, 2011, 11:21 p.m.
Message ID <1323559283-8049-4-git-send-email-rth@redhat.com>
Download mbox | patch
Permalink /patch/130588/
State New
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Comments

Richard Henderson - Dec. 10, 2011, 11:21 p.m.
---
 libitm/Makefile.am                   |    3 +
 libitm/Makefile.in                   |   20 +++--
 libitm/config/arm/hwcap.cc           |   67 +++++++++++++++++
 libitm/config/arm/hwcap.h            |   41 ++++++++++
 libitm/config/arm/sjlj.S             |  135 ++++++++++++++++++++++++++++++++++
 libitm/config/arm/target.h           |   62 ++++++++++++++++
 libitm/config/generic/asmcfi.h       |   13 ++-
 libitm/config/linux/arm/futex_bits.h |   48 ++++++++++++
 libitm/configure                     |   18 ++++-
 libitm/configure.ac                  |    1 +
 libitm/configure.tgt                 |    2 +
 11 files changed, 395 insertions(+), 15 deletions(-)
 create mode 100644 libitm/config/arm/hwcap.cc
 create mode 100644 libitm/config/arm/hwcap.h
 create mode 100644 libitm/config/arm/sjlj.S
 create mode 100644 libitm/config/arm/target.h
 create mode 100644 libitm/config/linux/arm/futex_bits.h
Ramana Radhakrishnan - Dec. 12, 2011, 3:20 p.m.
Hi Richard,

Comments inline below..


On Sat, Dec 10, 2011 at 03:21:23PM -0800, Richard Henderson wrote:
> ---
>  libitm/Makefile.am                   |    3 +
>  libitm/Makefile.in                   |   20 +++--
>  libitm/config/arm/hwcap.cc           |   67 +++++++++++++++++
>  libitm/config/arm/hwcap.h            |   41 ++++++++++
>  libitm/config/arm/sjlj.S             |  135 ++++++++++++++++++++++++++++++++++
>  libitm/config/arm/target.h           |   62 ++++++++++++++++
>  libitm/config/generic/asmcfi.h       |   13 ++-
>  libitm/config/linux/arm/futex_bits.h |   48 ++++++++++++
>  libitm/configure                     |   18 ++++-
>  libitm/configure.ac                  |    1 +
>  libitm/configure.tgt                 |    2 +
>  11 files changed, 395 insertions(+), 15 deletions(-)
>  create mode 100644 libitm/config/arm/hwcap.cc
>  create mode 100644 libitm/config/arm/hwcap.h
>  create mode 100644 libitm/config/arm/sjlj.S
>  create mode 100644 libitm/config/arm/target.h
>  create mode 100644 libitm/config/linux/arm/futex_bits.h



>
> diff --git a/libitm/Makefile.am b/libitm/Makefile.am
> index 26e1ebc..d417026 100644
> --- a/libitm/Makefile.am
> +++ b/libitm/Makefile.am
> @@ -62,6 +62,9 @@ libitm_la_SOURCES = \
>  	query.cc retry.cc rwlock.cc useraction.cc util.cc \
>  	sjlj.S tls.cc method-serial.cc method-gl.cc
>
> +if ARCH_ARM
> +libitm_la_SOURCES += hwcap.cc
> +endif
>  if ARCH_X86
>  libitm_la_SOURCES += x86_sse.cc x86_avx.cc
>  x86_sse.lo : XCFLAGS += -msse
> diff --git a/libitm/Makefile.in b/libitm/Makefile.in
> index dc77382..5305f4c 100644
> --- a/libitm/Makefile.in
> +++ b/libitm/Makefile.in
> @@ -36,8 +36,9 @@ POST_UNINSTALL = :
>  build_triplet = @build@
>  host_triplet = @host@
>  target_triplet = @target@
> -@ARCH_X86_TRUE@am__append_1 = x86_sse.cc x86_avx.cc
> -@ARCH_FUTEX_TRUE@am__append_2 = futex.cc
> +@ARCH_ARM_TRUE@am__append_1 = hwcap.cc
> +@ARCH_X86_TRUE@am__append_2 = x86_sse.cc x86_avx.cc
> +@ARCH_FUTEX_TRUE@am__append_3 = futex.cc
>  subdir = .
>  DIST_COMMON = $(am__configure_deps) $(srcdir)/../config.guess \
>  	$(srcdir)/../config.sub $(srcdir)/../depcomp \
> @@ -99,15 +100,16 @@ libitm_la_LIBADD =
>  am__libitm_la_SOURCES_DIST = aatree.cc alloc.cc alloc_c.cc \
>  	alloc_cpp.cc barrier.cc beginend.cc clone.cc eh_cpp.cc \
>  	local.cc query.cc retry.cc rwlock.cc useraction.cc util.cc \
> -	sjlj.S tls.cc method-serial.cc method-gl.cc x86_sse.cc \
> -	x86_avx.cc futex.cc
> -@ARCH_X86_TRUE@am__objects_1 = x86_sse.lo x86_avx.lo
> -@ARCH_FUTEX_TRUE@am__objects_2 = futex.lo
> +	sjlj.S tls.cc method-serial.cc method-gl.cc hwcap.cc \
> +	x86_sse.cc x86_avx.cc futex.cc
> +@ARCH_ARM_TRUE@am__objects_1 = hwcap.lo
> +@ARCH_X86_TRUE@am__objects_2 = x86_sse.lo x86_avx.lo
> +@ARCH_FUTEX_TRUE@am__objects_3 = futex.lo
>  am_libitm_la_OBJECTS = aatree.lo alloc.lo alloc_c.lo alloc_cpp.lo \
>  	barrier.lo beginend.lo clone.lo eh_cpp.lo local.lo query.lo \
>  	retry.lo rwlock.lo useraction.lo util.lo sjlj.lo tls.lo \
>  	method-serial.lo method-gl.lo $(am__objects_1) \
> -	$(am__objects_2)
> +	$(am__objects_2) $(am__objects_3)
>  libitm_la_OBJECTS = $(am_libitm_la_OBJECTS)
>  DEFAULT_INCLUDES = -I.@am__isrc@
>  depcomp = $(SHELL) $(top_srcdir)/../depcomp
> @@ -376,7 +378,8 @@ libitm_la_LDFLAGS = $(libitm_version_info) $(libitm_version_script)
>  libitm_la_SOURCES = aatree.cc alloc.cc alloc_c.cc alloc_cpp.cc \
>  	barrier.cc beginend.cc clone.cc eh_cpp.cc local.cc query.cc \
>  	retry.cc rwlock.cc useraction.cc util.cc sjlj.S tls.cc \
> -	method-serial.cc method-gl.cc $(am__append_1) $(am__append_2)
> +	method-serial.cc method-gl.cc $(am__append_1) $(am__append_2) \
> +	$(am__append_3)
>
>  # Automake Documentation:
>  # If your package has Texinfo files in many directories, you can use the
> @@ -505,6 +508,7 @@ distclean-compile:
>  @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/clone.Plo@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/eh_cpp.Plo@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/futex.Plo@am__quote@
> +@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/hwcap.Plo@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/local.Plo@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/method-gl.Plo@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/method-serial.Plo@am__quote@
> diff --git a/libitm/config/arm/hwcap.cc b/libitm/config/arm/hwcap.cc
> new file mode 100644
> index 0000000..007c10e
> --- /dev/null
> +++ b/libitm/config/arm/hwcap.cc
> @@ -0,0 +1,67 @@
> +/* Copyright (C) 2011 Free Software Foundation, Inc.
> +   Contributed by Richard Henderson <rth@redhat.com>.
> +
> +   This file is part of the GNU Transactional Memory Library (libitm).
> +
> +   Libitm is free software; you can redistribute it and/or modify it
> +   under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   Libitm 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 General Public License for
> +   more details.
> +
> +   Under Section 7 of GPL version 3, you are granted additional
> +   permissions described in the GCC Runtime Library Exception, version
> +   3.1, as published by the Free Software Foundation.
> +
> +   You should have received a copy of the GNU General Public License and
> +   a copy of the GCC Runtime Library Exception along with this program;
> +   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* This file initializes GTM_hwcap in some os-specific way to indicate
> +   what ISA extensions are present for ARM.  */
> +
> +#include "libitm_i.h"
> +#include "hwcap.h"
> +
> +/* Begin by defaulting to whatever options were given to the compiler.  */
> +int GTM_hwcap HIDDEN = 0
> +#ifdef __VFP_FP__
> +  | HWCAP_ARM_VFP
> +#endif
> +#ifdef __IWMMXT__
> +  | HWCAP_ARM_IWMMXT
> +#endif
> +  ;
> +
> +#ifdef __linux__
> +#include <unistd.h>
> +#include <sys/fcntl.h>
> +#include <elf.h>
> +
> +static void __attribute__((constructor))
> +init_gtm_hwcap(void)
> +{
> +  int fd = open ("/proc/self/auxv", O_RDONLY);
> +  if (fd < 0)
> +    return;
> +
> +  Elf32_auxv_t pairs[512];
> +  ssize_t rlen = read (fd, pairs, sizeof(pairs));
> +  close (fd);
> +  if (rlen < 0)
> +    return;
> +
> +  size_t n = (size_t)rlen / sizeof(pairs[0]);
> +  for (size_t i = 0; i < n; ++i)
> +    if (pairs[i].a_type == AT_HWCAP)
> +      {
> +	GTM_hwcap = pairs[i].a_un.a_val;
> +	return;
> +      }
> +}
> +#endif
> diff --git a/libitm/config/arm/hwcap.h b/libitm/config/arm/hwcap.h
> new file mode 100644
> index 0000000..16e4034
> --- /dev/null
> +++ b/libitm/config/arm/hwcap.h
> @@ -0,0 +1,41 @@
> +/* Copyright (C) 2011 Free Software Foundation, Inc.
> +   Contributed by Richard Henderson <rth@redhat.com>.
> +
> +   This file is part of the GNU Transactional Memory Library (libitm).
> +
> +   Libitm is free software; you can redistribute it and/or modify it
> +   under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   Libitm 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 General Public License for
> +   more details.
> +
> +   Under Section 7 of GPL version 3, you are granted additional
> +   permissions described in the GCC Runtime Library Exception, version
> +   3.1, as published by the Free Software Foundation.
> +
> +   You should have received a copy of the GNU General Public License and
> +   a copy of the GCC Runtime Library Exception along with this program;
> +   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* The following must match the kernel's <asm/procinfo.h>.  */
> +#define HWCAP_ARM_SWP           1
> +#define HWCAP_ARM_HALF          2
> +#define HWCAP_ARM_THUMB         4
> +#define HWCAP_ARM_26BIT         8
> +#define HWCAP_ARM_FAST_MULT     16
> +#define HWCAP_ARM_FPA           32
> +#define HWCAP_ARM_VFP           64
> +#define HWCAP_ARM_EDSP          128
> +#define HWCAP_ARM_JAVA          256
> +#define HWCAP_ARM_IWMMXT        512
> +#define HWCAP_ARM_CRUNCH        1024
> +#define HWCAP_ARM_THUMBEE       2048
> +#define HWCAP_ARM_NEON          4096
> +#define HWCAP_ARM_VFPv3         8192
> +#define HWCAP_ARM_VFPv3D16      16384


> +
> diff --git a/libitm/config/arm/sjlj.S b/libitm/config/arm/sjlj.S
> new file mode 100644
> index 0000000..cf2ae4b
> --- /dev/null
> +++ b/libitm/config/arm/sjlj.S
> @@ -0,0 +1,135 @@
> +/* Copyright (C) 2011 Free Software Foundation, Inc.
> +   Contributed by Richard Henderson <rth@redhat.com>.
> +
> +   This file is part of the GNU Transactional Memory Library (libitm).
> +
> +   Libitm is free software; you can redistribute it and/or modify it
> +   under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   Libitm 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 General Public License for
> +   more details.
> +
> +   Under Section 7 of GPL version 3, you are granted additional
> +   permissions described in the GCC Runtime Library Exception, version
> +   3.1, as published by the Free Software Foundation.
> +
> +   You should have received a copy of the GNU General Public License and
> +   a copy of the GCC Runtime Library Exception along with this program;
> +   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include "hwcap.h"
> +#include "asmcfi.h"
> +
> +	.syntax	unified
> +
> +#if defined(__thumb__)
> +        .thumb
> +        .thumb_func
> +#endif

This ain't gonna cut it for Thumb1 - Thus
replace that with if defined(__thumb2)

.syntax unified and Thumb1 don't cut it together
unfortunately . Also the ldc instructions wouldn't work
at Thumb1.




> +
> +/* ??? Use movw/movt when possible.  */

You can use movw/movt with this complex condition I think

#if (defined (thumb) && defined(__ARM_ARCH_6T2__)) || defined (__ARM_ARCH_7A__)
|| defined (__ARM_ARCH_7R__) || defined (__ARM_ARCH_7M__)

> +#if defined(PIC)
> +.macro ldaddr reg, addr
> +	ldr	\reg, 99f
> +	ldr	\reg, [\reg]
> +98:	add	\reg, \reg, pc
> +.subsection 1
> +99:	.word	\addr - (98b + 8)

This can't be right for Thumb2 state . PC is PC + 4 for Thumb2
unless I'm missing something right now.

> +.subsection 0
> +.endm
> +#else
> +.macro ldaddr reg, addr
> +	ldr	\reg, =\addr
> +.endm
> +#endif
> +
> +	.text
> +	.align	2
> +	.global	_ITM_beginTransaction
> +	.type	_ITM_beginTransaction, %function
> +
> +_ITM_beginTransaction:
> +	.fnstart
> +	cfi_startproc
> +#ifdef __thumb__
> +	mov	ip, sp
> +	push	{ r4-r11, ip, lr }
> +#else
> +	push	{ r4-r11, sp, lr }

The assembler should have warned this case as well
since this really is an UNPREDICTABLE instruction.
SP can't really be in the register list for a push.
Thus you shouldn't need a __thumb__ case.

> +#endif
> +	.save	{ lr }
> +	.pad	#(9*4)
> +	cfi_adjust_cfa_offset(40)
> +	cfi_rel_offset(lr, 36)
> +	sub	sp, sp, #(14*8)
> +	.pad	#(14*8)
> +	cfi_adjust_cfa_offset(14*8)
> +
> +	ldaddr	r2, GTM_hwcap
> +
> +	/* Store the VFP registers.  Don't use VFP instructions directly
> +	   because this code is used in non-VFP multilibs.  */
> +	tst	r2, #HWCAP_ARM_VFP
> +	it	ne
> +	stcne	p11, cr8, [sp], {16}	/* vstmne sp, {d8-d15} */
> +
> +	/* Save the call-preserved iWMMXt registers.  */
> +	tst	r2, #HWCAP_ARM_IWMMXT
> +	beq	1f
> +	stcl	p1, cr10, [sp, #64]	/* wstrd wr10, [sp, #64] */
> +	stcl	p1, cr11, [sp, #72]
> +	stcl	p1, cr12, [sp, #80]
> +	stcl	p1, cr13, [sp, #88]
> +	stcl	p1, cr14, [sp, #96]
> +	stcl	p1, cr15, [sp, #104]
> +1:
> +	/* Invoke GTM_begin_transaction with the struct we just built.  */
> +	mov	r1, sp
> +	bl	GTM_begin_transaction
> +
> +	/* Return; we don't need to restore any of the call-saved regs.  */
> +	add     sp, sp, #(14*8 + 9*4)
> +	cfi_adjust_cfa_offset(-(14*8 + 9*4))
> +	pop	{ pc }
> +	.fnend
> +	cfi_endproc
> +	.size	_ITM_beginTransaction, . - _ITM_beginTransaction
> +
> +	.global	GTM_longjmp
> +	.hidden	GTM_longjmp
> +	.type	GTM_longjmp, %function
> +
> +GTM_longjmp:
> +	ldaddr	r2, GTM_hwcap
> +
> +	tst	r2, #HWCAP_ARM_VFP
> +	it	ne
> +	ldcne	p11, cr8, [r1], {16}	/* vldmiane r1, {d8-d15} */
> +
> +	tst	r2, #HWCAP_ARM_IWMMXT
> +	beq	1f
> +	ldcl	p1, cr10, [r1, #64]	/* wldrd wr10, [r1, #64] */
> +	ldcl	p1, cr11, [r1, #72]
> +	ldcl	p1, cr12, [r1, #80]
> +	ldcl	p1, cr13, [r1, #88]
> +	ldcl	p1, cr14, [r1, #96]
> +	ldcl	p1, cr15, [r1, #104]
> +1:
> +	add	r1, r1, #(14*8)		/* Skip both VFP and iWMMXt blocks */
> +#ifdef __thumb__
> +	ldm	r1, { r4-r11, ip, lr }
> +	mov	sp, ip
> +	bx	lr
> +#else
> +	ldm	r1, { r4-r11, sp, pc }
> +#endif
> +	.size	GTM_longjmp, . - GTM_longjmp
> +
> +#ifdef __linux__
> +.section .note.GNU-stack, "", %progbits
> +#endif
> diff --git a/libitm/config/arm/target.h b/libitm/config/arm/target.h
> new file mode 100644
> index 0000000..99dd99a
> --- /dev/null
> +++ b/libitm/config/arm/target.h
> @@ -0,0 +1,62 @@
> +/* Copyright (C) 2011 Free Software Foundation, Inc.
> +   Contributed by Richard Henderson <rth@redhat.com>.
> +
> +   This file is part of the GNU Transactional Memory Library (libitm).
> +
> +   Libitm is free software; you can redistribute it and/or modify it
> +   under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   Libitm 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 General Public License for
> +   more details.
> +
> +   Under Section 7 of GPL version 3, you are granted additional
> +   permissions described in the GCC Runtime Library Exception, version
> +   3.1, as published by the Free Software Foundation.
> +
> +   You should have received a copy of the GNU General Public License and
> +   a copy of the GCC Runtime Library Exception along with this program;
> +   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +namespace GTM HIDDEN {
> +
> +typedef struct gtm_jmpbuf
> +{
> +  unsigned long long vfp[8];	/* d8-d15 */
> +  unsigned long long iwmmxt[6];	/* cr10-cr15 */
> +  unsigned long gr[8];		/* r4-r11 */
> +  void *cfa;
> +  unsigned long pc;
> +} gtm_jmpbuf;
> +
> +/* ARM generally uses a fixed page size of 4K.  */<
> +#define PAGE_SIZE	4096
> +#define FIXED_PAGE_SIZE	1
> +
> +/* ??? The size of one line in hardware caches (in bytes). */
> +#define HW_CACHELINE_SIZE 64
> +
> +static inline void
> +cpu_relax (void)
> +{
> +  /* ??? Maybe use WFE.  */
> +  __asm volatile ("" : : : "memory");
> +}

Should this be similar to cpu_relax
in the kernel ? On some cores I
thought we'd end up having to do
have to use __sync_synchronize.

> +
> +static inline void
> +atomic_read_barrier (void)
> +{
> +  __sync_synchronize ();
> +}
> +
> +static inline void
> +atomic_write_barrier (void)
> +{
> +  __sync_synchronize ();
> +}
> +
> +} // namespace GTM
> diff --git a/libitm/config/generic/asmcfi.h b/libitm/config/generic/asmcfi.h
> index 4344d6f..bb7f98f 100644
> --- a/libitm/config/generic/asmcfi.h
> +++ b/libitm/config/generic/asmcfi.h
> @@ -27,16 +27,19 @@
>
>  #ifdef HAVE_AS_CFI_PSEUDO_OP
>
> -#define cfi_startproc		.cfi_startproc
> -#define cfi_endproc		.cfi_endproc
> -#define cfi_def_cfa_offset(n)	.cfi_def_cfa_offset n
> -#define cfi_def_cfa(r,n)	.cfi_def_cfa r, n
> -#define cfi_register(o,n)	.cfi_register o, n
> +#define cfi_startproc			.cfi_startproc
> +#define cfi_endproc			.cfi_endproc
> +#define cfi_adjust_cfa_offset(n)	.cfi_adjust_cfa_offset n
> +#define cfi_def_cfa_offset(n)		.cfi_def_cfa_offset n
> +#define cfi_def_cfa(r,n)		.cfi_def_cfa r, n
> +#define cfi_rel_offset(r,o)		.cfi_rel_offset r, o
> +#define cfi_register(o,n)		.cfi_register o, n
>
>  #else
>
>  #define cfi_startproc
>  #define cfi_endproc
> +#define cfi_adjust_cfa_offset(n)
>  #define cfi_def_cfa_offset(n)
>  #define cfi_def_cfa(r,n)
>  #define cfi_register(o,n)
> diff --git a/libitm/config/linux/arm/futex_bits.h b/libitm/config/linux/arm/futex_bits.h
> new file mode 100644
> index 0000000..7e1b52f
> --- /dev/null
> +++ b/libitm/config/linux/arm/futex_bits.h
> @@ -0,0 +1,48 @@
> +/* Copyright (C) 2011 Free Software Foundation, Inc.
> +   Contributed by Richard Henderson <rth@redhat.com>.
> +
> +   This file is part of the GNU Transactional Memory Library (libitm).
> +
> +   Libitm is free software; you can redistribute it and/or modify it
> +   under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   Libitm 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 General Public License for
> +   more details.
> +
> +   Under Section 7 of GPL version 3, you are granted additional
> +   permissions described in the GCC Runtime Library Exception, version
> +   3.1, as published by the Free Software Foundation.
> +
> +   You should have received a copy of the GNU General Public License and
> +   a copy of the GCC Runtime Library Exception along with this program;
ou> +   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* Provide target-specific access to the futex system call.  */
> +
> +#include <sys/syscall.h>
> +
> +static inline long
> +sys_futex0 (int *addr, long op, long val)
> +{
> +  register long sc_0 __asm__("r0");
> +  register long sc_1 __asm__("r1");
> +  register long sc_2 __asm__("r2");
> +  register long sc_3 __asm__("r3");
> +
> +  sc_0 = (long) addr;
> +  sc_1 = op;
> +  sc_2 = val;
> +  sc_3 = 0;
> +
> +  __asm volatile ("swi %1"
> +		  : "+r"(sc_0)
> +		  : "i"(SYS_futex), "r"(sc_1), "r"(sc_2), "r"(sc_3)
> +		  : "memory");
> +
> +  return sc_0;
> +}

Hmmm why is this still using the old syscall interface ? I see that
Joseph commented on this in a previous review.

Thus I don't think this is right as it stands today.

cheers
Ramana
Richard Earnshaw - Dec. 14, 2011, 6:25 p.m.
On 10/12/11 23:21, Richard Henderson wrote:
> diff --git a/libitm/config/arm/hwcap.h b/libitm/config/arm/hwcap.h
> new file mode 100644
> index 0000000..16e4034
> --- /dev/null
> +++ b/libitm/config/arm/hwcap.h
> +
> +/* The following must match the kernel's <asm/procinfo.h>.  */
> +#define HWCAP_ARM_SWP           1

All of these defines are linux-specific.  Shouldn't they be wrapped as such?


> diff --git a/libitm/config/arm/sjlj.S b/libitm/config/arm/sjlj.S
> new file mode 100644
> index 0000000..cf2ae4b
> --- /dev/null
> +++ b/libitm/config/arm/sjlj.S

> +/* ??? Use movw/movt when possible.  */
> +#if defined(PIC)
> +.macro ldaddr reg, addr
> +       ldr     \reg, 99f
> +       ldr     \reg, [\reg]
> +98:    add     \reg, \reg, pc
> +.subsection 1
> +99:    .word   \addr - (98b + 8)
> +.subsection 0
> +.endm

That can't be right.  The first instruction loads from your literal
block an address difference, then your second instruction tries to use
that as an address.

Why don't you just write

.macro ldaddr	reg, addr
	ldr	\reg, =(\addr - 99b + PC_OFFS)
99:	add	\reg, \reg, pc
.endm


> +       /* Store the VFP registers.  Don't use VFP instructions directly
> +          because this code is used in non-VFP multilibs.  */
> +       tst     r2, #HWCAP_ARM_VFP
> +       it      ne
> +       stcne   p11, cr8, [sp], {16}    /* vstmne sp, {d8-d15} */

You shouldn't rely on the conditional STC instruction not trapping if
the condition test fails.  Conditionally NOT executing an instruction is
implementation defined if the instruction itself is undefined.  Just
branch round it as you've done for the other instructions below.

> +
> +GTM_longjmp:
> +       ldaddr  r2, GTM_hwcap
> +
> +       tst     r2, #HWCAP_ARM_VFP
> +       it      ne
> +       ldcne   p11, cr8, [r1], {16}    /* vldmiane r1, {d8-d15} */

As above.

> +
> +       tst     r2, #HWCAP_ARM_IWMMXT
> +       beq     1f
> +       ldcl    p1, cr10, [r1, #64]     /* wldrd wr10, [r1, #64] */
> +       ldcl    p1, cr11, [r1, #72]
> +       ldcl    p1, cr12, [r1, #80]
> +       ldcl    p1, cr13, [r1, #88]
> +       ldcl    p1, cr14, [r1, #96]
> +       ldcl    p1, cr15, [r1, #104]
> +1:
> +       add     r1, r1, #(14*8)         /* Skip both VFP and iWMMXt blocks */
> +#ifdef __thumb__
> +       ldm     r1, { r4-r11, ip, lr }
> +       mov     sp, ip
> +       bx      lr
> +#else
> +       ldm     r1, { r4-r11, sp, pc }

Isn't this buffer on the stack?  And won't loading SP cause the buffer
to become deallocated?  If so, then you need to use the same code as
Thumb to avoid undefined behaviour if the instruction is interrupted
before completion (since SP won't be restored).

Otherwise, with the changes for Ramana's comments, this is OK.

R.
Richard Henderson - Dec. 14, 2011, 7:48 p.m.
On 12/14/2011 10:25 AM, Richard Earnshaw wrote:
> On 10/12/11 23:21, Richard Henderson wrote:
>> diff --git a/libitm/config/arm/hwcap.h b/libitm/config/arm/hwcap.h
>> new file mode 100644
>> index 0000000..16e4034
>> --- /dev/null
>> +++ b/libitm/config/arm/hwcap.h
>> +
>> +/* The following must match the kernel's <asm/procinfo.h>.  */
>> +#define HWCAP_ARM_SWP           1
> 
> All of these defines are linux-specific.  Shouldn't they be wrapped as such?

Well, we need *some* values for other targets.  Shouldn't they match, failing some other useful value  to put in?

> That can't be right.  The first instruction loads from your literal
> block an address difference, then your second instruction tries to use
> that as an address.

Yes, that's fixed in the followup that's been posed, wrt movw+movt.

> Why don't you just write
> 
> .macro ldaddr	reg, addr
> 	ldr	\reg, =(\addr - 99b + PC_OFFS)
> 99:	add	\reg, \reg, pc
> .endm

That was the first thing I tried.  Unfortunately, the assembler doesn't accept arbitrary expressions.  That's arguably a bug...

>> +       /* Store the VFP registers.  Don't use VFP instructions directly
>> +          because this code is used in non-VFP multilibs.  */
>> +       tst     r2, #HWCAP_ARM_VFP
>> +       it      ne
>> +       stcne   p11, cr8, [sp], {16}    /* vstmne sp, {d8-d15} */
> 
> You shouldn't rely on the conditional STC instruction not trapping if
> the condition test fails.  Conditionally NOT executing an instruction is
> implementation defined if the instruction itself is undefined.  Just
> branch round it as you've done for the other instructions below.

Fair enough.

>> +       ldm     r1, { r4-r11, sp, pc }
> 
> Isn't this buffer on the stack?

No.  We passed the buffer in on the stack, but we subsequently copied it elsewhere.


r~
Joseph S. Myers - Dec. 16, 2011, 9:45 p.m.
On Sat, 10 Dec 2011, Richard Henderson wrote:

> +/* Begin by defaulting to whatever options were given to the compiler.  */
> +int GTM_hwcap HIDDEN = 0
> +#ifdef __VFP_FP__
> +  | HWCAP_ARM_VFP
> +#endif
> +#ifdef __IWMMXT__
> +  | HWCAP_ARM_IWMMXT
> +#endif
> +  ;

It doesn't matter much since this value should be overridden at runtime 
from /proc/self/auxv, but I think the relevant VFP test is defined 
(__VFP_FP__) && !defined (__SOFTFP__), since __VFP_FP__ just tests the 
floating-point format and not whether VFP instructions are enabled.

Patch

diff --git a/libitm/Makefile.am b/libitm/Makefile.am
index 26e1ebc..d417026 100644
--- a/libitm/Makefile.am
+++ b/libitm/Makefile.am
@@ -62,6 +62,9 @@  libitm_la_SOURCES = \
 	query.cc retry.cc rwlock.cc useraction.cc util.cc \
 	sjlj.S tls.cc method-serial.cc method-gl.cc
 
+if ARCH_ARM
+libitm_la_SOURCES += hwcap.cc
+endif
 if ARCH_X86
 libitm_la_SOURCES += x86_sse.cc x86_avx.cc
 x86_sse.lo : XCFLAGS += -msse
diff --git a/libitm/Makefile.in b/libitm/Makefile.in
index dc77382..5305f4c 100644
--- a/libitm/Makefile.in
+++ b/libitm/Makefile.in
@@ -36,8 +36,9 @@  POST_UNINSTALL = :
 build_triplet = @build@
 host_triplet = @host@
 target_triplet = @target@
-@ARCH_X86_TRUE@am__append_1 = x86_sse.cc x86_avx.cc
-@ARCH_FUTEX_TRUE@am__append_2 = futex.cc
+@ARCH_ARM_TRUE@am__append_1 = hwcap.cc
+@ARCH_X86_TRUE@am__append_2 = x86_sse.cc x86_avx.cc
+@ARCH_FUTEX_TRUE@am__append_3 = futex.cc
 subdir = .
 DIST_COMMON = $(am__configure_deps) $(srcdir)/../config.guess \
 	$(srcdir)/../config.sub $(srcdir)/../depcomp \
@@ -99,15 +100,16 @@  libitm_la_LIBADD =
 am__libitm_la_SOURCES_DIST = aatree.cc alloc.cc alloc_c.cc \
 	alloc_cpp.cc barrier.cc beginend.cc clone.cc eh_cpp.cc \
 	local.cc query.cc retry.cc rwlock.cc useraction.cc util.cc \
-	sjlj.S tls.cc method-serial.cc method-gl.cc x86_sse.cc \
-	x86_avx.cc futex.cc
-@ARCH_X86_TRUE@am__objects_1 = x86_sse.lo x86_avx.lo
-@ARCH_FUTEX_TRUE@am__objects_2 = futex.lo
+	sjlj.S tls.cc method-serial.cc method-gl.cc hwcap.cc \
+	x86_sse.cc x86_avx.cc futex.cc
+@ARCH_ARM_TRUE@am__objects_1 = hwcap.lo
+@ARCH_X86_TRUE@am__objects_2 = x86_sse.lo x86_avx.lo
+@ARCH_FUTEX_TRUE@am__objects_3 = futex.lo
 am_libitm_la_OBJECTS = aatree.lo alloc.lo alloc_c.lo alloc_cpp.lo \
 	barrier.lo beginend.lo clone.lo eh_cpp.lo local.lo query.lo \
 	retry.lo rwlock.lo useraction.lo util.lo sjlj.lo tls.lo \
 	method-serial.lo method-gl.lo $(am__objects_1) \
-	$(am__objects_2)
+	$(am__objects_2) $(am__objects_3)
 libitm_la_OBJECTS = $(am_libitm_la_OBJECTS)
 DEFAULT_INCLUDES = -I.@am__isrc@
 depcomp = $(SHELL) $(top_srcdir)/../depcomp
@@ -376,7 +378,8 @@  libitm_la_LDFLAGS = $(libitm_version_info) $(libitm_version_script)
 libitm_la_SOURCES = aatree.cc alloc.cc alloc_c.cc alloc_cpp.cc \
 	barrier.cc beginend.cc clone.cc eh_cpp.cc local.cc query.cc \
 	retry.cc rwlock.cc useraction.cc util.cc sjlj.S tls.cc \
-	method-serial.cc method-gl.cc $(am__append_1) $(am__append_2)
+	method-serial.cc method-gl.cc $(am__append_1) $(am__append_2) \
+	$(am__append_3)
 
 # Automake Documentation:
 # If your package has Texinfo files in many directories, you can use the
@@ -505,6 +508,7 @@  distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/clone.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/eh_cpp.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/futex.Plo@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/hwcap.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/local.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/method-gl.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/method-serial.Plo@am__quote@
diff --git a/libitm/config/arm/hwcap.cc b/libitm/config/arm/hwcap.cc
new file mode 100644
index 0000000..007c10e
--- /dev/null
+++ b/libitm/config/arm/hwcap.cc
@@ -0,0 +1,67 @@ 
+/* Copyright (C) 2011 Free Software Foundation, Inc.
+   Contributed by Richard Henderson <rth@redhat.com>.
+
+   This file is part of the GNU Transactional Memory Library (libitm).
+
+   Libitm is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   Libitm 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 General Public License for
+   more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* This file initializes GTM_hwcap in some os-specific way to indicate
+   what ISA extensions are present for ARM.  */
+
+#include "libitm_i.h"
+#include "hwcap.h"
+
+/* Begin by defaulting to whatever options were given to the compiler.  */
+int GTM_hwcap HIDDEN = 0
+#ifdef __VFP_FP__
+  | HWCAP_ARM_VFP
+#endif
+#ifdef __IWMMXT__
+  | HWCAP_ARM_IWMMXT
+#endif
+  ;
+
+#ifdef __linux__
+#include <unistd.h>
+#include <sys/fcntl.h>
+#include <elf.h>
+
+static void __attribute__((constructor))
+init_gtm_hwcap(void)
+{
+  int fd = open ("/proc/self/auxv", O_RDONLY);
+  if (fd < 0)
+    return;
+
+  Elf32_auxv_t pairs[512];
+  ssize_t rlen = read (fd, pairs, sizeof(pairs));
+  close (fd);
+  if (rlen < 0)
+    return;
+
+  size_t n = (size_t)rlen / sizeof(pairs[0]);
+  for (size_t i = 0; i < n; ++i)
+    if (pairs[i].a_type == AT_HWCAP)
+      {
+	GTM_hwcap = pairs[i].a_un.a_val;
+	return;
+      }
+}
+#endif
diff --git a/libitm/config/arm/hwcap.h b/libitm/config/arm/hwcap.h
new file mode 100644
index 0000000..16e4034
--- /dev/null
+++ b/libitm/config/arm/hwcap.h
@@ -0,0 +1,41 @@ 
+/* Copyright (C) 2011 Free Software Foundation, Inc.
+   Contributed by Richard Henderson <rth@redhat.com>.
+
+   This file is part of the GNU Transactional Memory Library (libitm).
+
+   Libitm is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   Libitm 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 General Public License for
+   more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* The following must match the kernel's <asm/procinfo.h>.  */
+#define HWCAP_ARM_SWP           1
+#define HWCAP_ARM_HALF          2
+#define HWCAP_ARM_THUMB         4
+#define HWCAP_ARM_26BIT         8
+#define HWCAP_ARM_FAST_MULT     16
+#define HWCAP_ARM_FPA           32
+#define HWCAP_ARM_VFP           64
+#define HWCAP_ARM_EDSP          128
+#define HWCAP_ARM_JAVA          256
+#define HWCAP_ARM_IWMMXT        512
+#define HWCAP_ARM_CRUNCH        1024
+#define HWCAP_ARM_THUMBEE       2048
+#define HWCAP_ARM_NEON          4096
+#define HWCAP_ARM_VFPv3         8192
+#define HWCAP_ARM_VFPv3D16      16384
+
diff --git a/libitm/config/arm/sjlj.S b/libitm/config/arm/sjlj.S
new file mode 100644
index 0000000..cf2ae4b
--- /dev/null
+++ b/libitm/config/arm/sjlj.S
@@ -0,0 +1,135 @@ 
+/* Copyright (C) 2011 Free Software Foundation, Inc.
+   Contributed by Richard Henderson <rth@redhat.com>.
+
+   This file is part of the GNU Transactional Memory Library (libitm).
+
+   Libitm is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   Libitm 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 General Public License for
+   more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include "hwcap.h"
+#include "asmcfi.h"
+
+	.syntax	unified
+
+#if defined(__thumb__)
+        .thumb
+        .thumb_func
+#endif
+
+/* ??? Use movw/movt when possible.  */
+#if defined(PIC)
+.macro ldaddr reg, addr
+	ldr	\reg, 99f
+	ldr	\reg, [\reg]
+98:	add	\reg, \reg, pc
+.subsection 1
+99:	.word	\addr - (98b + 8)
+.subsection 0
+.endm
+#else
+.macro ldaddr reg, addr
+	ldr	\reg, =\addr
+.endm
+#endif
+
+	.text
+	.align	2
+	.global	_ITM_beginTransaction
+	.type	_ITM_beginTransaction, %function
+
+_ITM_beginTransaction:
+	.fnstart
+	cfi_startproc
+#ifdef __thumb__
+	mov	ip, sp
+	push	{ r4-r11, ip, lr }
+#else
+	push	{ r4-r11, sp, lr }
+#endif
+	.save	{ lr }
+	.pad	#(9*4)
+	cfi_adjust_cfa_offset(40)
+	cfi_rel_offset(lr, 36)
+	sub	sp, sp, #(14*8)
+	.pad	#(14*8)
+	cfi_adjust_cfa_offset(14*8)
+
+	ldaddr	r2, GTM_hwcap
+
+	/* Store the VFP registers.  Don't use VFP instructions directly
+	   because this code is used in non-VFP multilibs.  */
+	tst	r2, #HWCAP_ARM_VFP
+	it	ne
+	stcne	p11, cr8, [sp], {16}	/* vstmne sp, {d8-d15} */
+
+	/* Save the call-preserved iWMMXt registers.  */
+	tst	r2, #HWCAP_ARM_IWMMXT
+	beq	1f
+	stcl	p1, cr10, [sp, #64]	/* wstrd wr10, [sp, #64] */
+	stcl	p1, cr11, [sp, #72]
+	stcl	p1, cr12, [sp, #80]
+	stcl	p1, cr13, [sp, #88]
+	stcl	p1, cr14, [sp, #96]
+	stcl	p1, cr15, [sp, #104]
+1:
+	/* Invoke GTM_begin_transaction with the struct we just built.  */
+	mov	r1, sp
+	bl	GTM_begin_transaction
+
+	/* Return; we don't need to restore any of the call-saved regs.  */
+	add     sp, sp, #(14*8 + 9*4)
+	cfi_adjust_cfa_offset(-(14*8 + 9*4))
+	pop	{ pc }
+	.fnend
+	cfi_endproc
+	.size	_ITM_beginTransaction, . - _ITM_beginTransaction
+
+	.global	GTM_longjmp
+	.hidden	GTM_longjmp
+	.type	GTM_longjmp, %function
+
+GTM_longjmp:
+	ldaddr	r2, GTM_hwcap
+
+	tst	r2, #HWCAP_ARM_VFP
+	it	ne
+	ldcne	p11, cr8, [r1], {16}	/* vldmiane r1, {d8-d15} */
+
+	tst	r2, #HWCAP_ARM_IWMMXT
+	beq	1f
+	ldcl	p1, cr10, [r1, #64]	/* wldrd wr10, [r1, #64] */
+	ldcl	p1, cr11, [r1, #72]
+	ldcl	p1, cr12, [r1, #80]
+	ldcl	p1, cr13, [r1, #88]
+	ldcl	p1, cr14, [r1, #96]
+	ldcl	p1, cr15, [r1, #104]
+1:
+	add	r1, r1, #(14*8)		/* Skip both VFP and iWMMXt blocks */
+#ifdef __thumb__
+	ldm	r1, { r4-r11, ip, lr }
+	mov	sp, ip
+	bx	lr
+#else
+	ldm	r1, { r4-r11, sp, pc }
+#endif
+	.size	GTM_longjmp, . - GTM_longjmp
+
+#ifdef __linux__
+.section .note.GNU-stack, "", %progbits
+#endif
diff --git a/libitm/config/arm/target.h b/libitm/config/arm/target.h
new file mode 100644
index 0000000..99dd99a
--- /dev/null
+++ b/libitm/config/arm/target.h
@@ -0,0 +1,62 @@ 
+/* Copyright (C) 2011 Free Software Foundation, Inc.
+   Contributed by Richard Henderson <rth@redhat.com>.
+
+   This file is part of the GNU Transactional Memory Library (libitm).
+
+   Libitm is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   Libitm 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 General Public License for
+   more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+namespace GTM HIDDEN {
+
+typedef struct gtm_jmpbuf
+{
+  unsigned long long vfp[8];	/* d8-d15 */
+  unsigned long long iwmmxt[6];	/* cr10-cr15 */
+  unsigned long gr[8];		/* r4-r11 */
+  void *cfa;
+  unsigned long pc;
+} gtm_jmpbuf;
+
+/* ARM generally uses a fixed page size of 4K.  */
+#define PAGE_SIZE	4096
+#define FIXED_PAGE_SIZE	1
+
+/* ??? The size of one line in hardware caches (in bytes). */
+#define HW_CACHELINE_SIZE 64
+
+static inline void
+cpu_relax (void)
+{
+  /* ??? Maybe use WFE.  */
+  __asm volatile ("" : : : "memory");
+}
+
+static inline void
+atomic_read_barrier (void)
+{
+  __sync_synchronize ();
+}
+
+static inline void
+atomic_write_barrier (void)
+{
+  __sync_synchronize ();
+}
+
+} // namespace GTM
diff --git a/libitm/config/generic/asmcfi.h b/libitm/config/generic/asmcfi.h
index 4344d6f..bb7f98f 100644
--- a/libitm/config/generic/asmcfi.h
+++ b/libitm/config/generic/asmcfi.h
@@ -27,16 +27,19 @@ 
 
 #ifdef HAVE_AS_CFI_PSEUDO_OP
 
-#define cfi_startproc		.cfi_startproc
-#define cfi_endproc		.cfi_endproc
-#define cfi_def_cfa_offset(n)	.cfi_def_cfa_offset n
-#define cfi_def_cfa(r,n)	.cfi_def_cfa r, n
-#define cfi_register(o,n)	.cfi_register o, n
+#define cfi_startproc			.cfi_startproc
+#define cfi_endproc			.cfi_endproc
+#define cfi_adjust_cfa_offset(n)	.cfi_adjust_cfa_offset n
+#define cfi_def_cfa_offset(n)		.cfi_def_cfa_offset n
+#define cfi_def_cfa(r,n)		.cfi_def_cfa r, n
+#define cfi_rel_offset(r,o)		.cfi_rel_offset r, o
+#define cfi_register(o,n)		.cfi_register o, n
 
 #else
 
 #define cfi_startproc
 #define cfi_endproc
+#define cfi_adjust_cfa_offset(n)
 #define cfi_def_cfa_offset(n)
 #define cfi_def_cfa(r,n)
 #define cfi_register(o,n)
diff --git a/libitm/config/linux/arm/futex_bits.h b/libitm/config/linux/arm/futex_bits.h
new file mode 100644
index 0000000..7e1b52f
--- /dev/null
+++ b/libitm/config/linux/arm/futex_bits.h
@@ -0,0 +1,48 @@ 
+/* Copyright (C) 2011 Free Software Foundation, Inc.
+   Contributed by Richard Henderson <rth@redhat.com>.
+
+   This file is part of the GNU Transactional Memory Library (libitm).
+
+   Libitm is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   Libitm 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 General Public License for
+   more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Provide target-specific access to the futex system call.  */
+
+#include <sys/syscall.h>
+
+static inline long
+sys_futex0 (int *addr, long op, long val)
+{
+  register long sc_0 __asm__("r0");
+  register long sc_1 __asm__("r1");
+  register long sc_2 __asm__("r2");
+  register long sc_3 __asm__("r3");
+
+  sc_0 = (long) addr;
+  sc_1 = op;
+  sc_2 = val;
+  sc_3 = 0;
+
+  __asm volatile ("swi %1"
+		  : "+r"(sc_0)
+		  : "i"(SYS_futex), "r"(sc_1), "r"(sc_2), "r"(sc_3)
+		  : "memory");
+
+  return sc_0;
+}
diff --git a/libitm/configure b/libitm/configure
index 9b06359..3abc793 100644
--- a/libitm/configure
+++ b/libitm/configure
@@ -607,6 +607,8 @@  ARCH_X86_AVX_FALSE
 ARCH_X86_AVX_TRUE
 ARCH_X86_FALSE
 ARCH_X86_TRUE
+ARCH_ARM_FALSE
+ARCH_ARM_TRUE
 link_itm
 XLDFLAGS
 XCFLAGS
@@ -11720,7 +11722,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11723 "configure"
+#line 11725 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11826,7 +11828,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11829 "configure"
+#line 11831 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -17369,6 +17371,14 @@  else
 fi
 
 
+ if test "$ARCH" = arm; then
+  ARCH_ARM_TRUE=
+  ARCH_ARM_FALSE='#'
+else
+  ARCH_ARM_TRUE='#'
+  ARCH_ARM_FALSE=
+fi
+
  if test "$ARCH" = x86; then
   ARCH_X86_TRUE=
   ARCH_X86_FALSE='#'
@@ -17542,6 +17552,10 @@  if test -z "${LIBITM_BUILD_VERSIONED_SHLIB_SUN_TRUE}" && test -z "${LIBITM_BUILD
   as_fn_error "conditional \"LIBITM_BUILD_VERSIONED_SHLIB_SUN\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
 fi
+if test -z "${ARCH_ARM_TRUE}" && test -z "${ARCH_ARM_FALSE}"; then
+  as_fn_error "conditional \"ARCH_ARM\" was never defined.
+Usually this means the macro was only invoked conditionally." "$LINENO" 5
+fi
 if test -z "${ARCH_X86_TRUE}" && test -z "${ARCH_X86_FALSE}"; then
   as_fn_error "conditional \"ARCH_X86\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
diff --git a/libitm/configure.ac b/libitm/configure.ac
index 45ee870..ab2a90b 100644
--- a/libitm/configure.ac
+++ b/libitm/configure.ac
@@ -273,6 +273,7 @@  else
 fi
 AC_SUBST(link_itm)
 
+AM_CONDITIONAL([ARCH_ARM], [test "$ARCH" = arm])
 AM_CONDITIONAL([ARCH_X86], [test "$ARCH" = x86])
 AM_CONDITIONAL([ARCH_X86_AVX], [test "$libitm_cv_as_avx" = yes])
 AM_CONDITIONAL([ARCH_FUTEX], [test $enable_linux_futex = yes])
diff --git a/libitm/configure.tgt b/libitm/configure.tgt
index eac6f50..a17f3fc 100644
--- a/libitm/configure.tgt
+++ b/libitm/configure.tgt
@@ -48,6 +48,8 @@  fi
 case "${target_cpu}" in
   alpha*)	ARCH=alpha ;;
 
+  arm*)		ARCH=arm ;;
+
   i[3456]86)
 	case " ${CC} ${CFLAGS} " in
 	  *" -m64 "*)