5035b7819c
Since libatomic_ops does not implement real atomic operations for ARMv4 and ARMv5, libunwind must define AO_REQUIRE_CAS do indicate it requires compare-and-swap operations, even if not available as real atomic operations for the current architecture. In this case, libatomic_ops will rely on emulated atomic operations, which also require linking against libatomic_ops, which was until now not done by libunwind. This fixes the mysterious ltrace build issue: http://autobuild.buildroot.org/results/e1b/e1b330abfa2d80f3f30bc3359428ea429c690eb8/ Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Cc: Baruch Siach <baruch@tkos.co.il> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
57 lines
2.1 KiB
Diff
57 lines
2.1 KiB
Diff
From 24484e80b3e329c9edee1995e102f8612eedb79c Mon Sep 17 00:00:00 2001
|
|
From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
|
|
Date: Tue, 13 May 2014 23:32:27 +0200
|
|
Subject: [PATCH] Add AO_REQUIRE_CAS to fix build on ARM < v6
|
|
|
|
ARM earlier than ARMv6, such as ARMv4 and ARMv5 do not provide
|
|
optimize atomic operations in libatomic_ops. Since libunwind is using
|
|
such operations, it should define AO_REQUIRE_CAS before including
|
|
<atomic_ops.h> so that libatomic_ops knows it should use emulated
|
|
atomic operations instead (even though they are obviously a lot more
|
|
expensive).
|
|
|
|
Also, while real atomic operations are all inline functions and
|
|
therefore linking against libatomic_ops was not required, the emulated
|
|
atomic operations actually require linking against libatomic_ops, so
|
|
the commented AC_CHECK_LIB test in acinclude.m4 is uncommented to make
|
|
sure we link against libatomic_ops.
|
|
|
|
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
|
|
---
|
|
acinclude.m4 | 8 +-------
|
|
include/libunwind_i.h | 1 +
|
|
2 files changed, 2 insertions(+), 7 deletions(-)
|
|
|
|
diff --git a/acinclude.m4 b/acinclude.m4
|
|
index 497f7c2..9c15af1 100644
|
|
--- a/acinclude.m4
|
|
+++ b/acinclude.m4
|
|
@@ -22,11 +22,5 @@ fi])
|
|
AC_DEFUN([CHECK_ATOMIC_OPS],
|
|
[dnl Check whether the system has the atomic_ops package installed.
|
|
AC_CHECK_HEADERS(atomic_ops.h)
|
|
-#
|
|
-# Don't link against libatomic_ops for now. We don't want libunwind
|
|
-# to depend on libatomic_ops.so. Fortunately, none of the platforms
|
|
-# we care about so far need libatomic_ops.a (everything is done via
|
|
-# inline macros).
|
|
-#
|
|
-# AC_CHECK_LIB(atomic_ops, main)
|
|
+ AC_CHECK_LIB(atomic_ops, main)
|
|
])
|
|
diff --git a/include/libunwind_i.h b/include/libunwind_i.h
|
|
index 23f615e..deabdfd 100644
|
|
--- a/include/libunwind_i.h
|
|
+++ b/include/libunwind_i.h
|
|
@@ -95,6 +95,7 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
|
|
(pthread_mutex_unlock != NULL ? pthread_mutex_unlock (l) : 0)
|
|
|
|
#ifdef HAVE_ATOMIC_OPS_H
|
|
+# define AO_REQUIRE_CAS
|
|
# include <atomic_ops.h>
|
|
static inline int
|
|
cmpxchg_ptr (void *addr, void *old, void *new)
|
|
--
|
|
1.9.2
|
|
|