| Patrick Williams | f1e5d69 | 2016-03-30 15:21:19 -0500 | [diff] [blame] | 1 | From 24484e80b3e329c9edee1995e102f8612eedb79c Mon Sep 17 00:00:00 2001 |
| 2 | From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> |
| 3 | Date: Tue, 13 May 2014 23:32:27 +0200 |
| 4 | Subject: [PATCH] Add AO_REQUIRE_CAS to fix build on ARM < v6 |
| 5 | |
| 6 | ARM earlier than ARMv6, such as ARMv4 and ARMv5 do not provide |
| 7 | optimize atomic operations in libatomic_ops. Since libunwind is using |
| 8 | such operations, it should define AO_REQUIRE_CAS before including |
| 9 | <atomic_ops.h> so that libatomic_ops knows it should use emulated |
| 10 | atomic operations instead (even though they are obviously a lot more |
| 11 | expensive). |
| 12 | |
| 13 | Also, while real atomic operations are all inline functions and |
| 14 | therefore linking against libatomic_ops was not required, the emulated |
| 15 | atomic operations actually require linking against libatomic_ops, so |
| 16 | the commented AC_CHECK_LIB test in acinclude.m4 is uncommented to make |
| 17 | sure we link against libatomic_ops. |
| 18 | |
| 19 | Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> |
| Patrick Williams | d8c66bc | 2016-06-20 12:57:21 -0500 | [diff] [blame] | 20 | Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com> |
| Patrick Williams | f1e5d69 | 2016-03-30 15:21:19 -0500 | [diff] [blame] | 21 | |
| 22 | Upstream-Status: Pending |
| 23 | Taken from: |
| 24 | https://raw.githubusercontent.com/rdnetto/teapot-buildroot/master/package/libunwind/libunwind-02-Add-AO_REQUIRE_CAS-to-fix-build-on-ARM-v6.patch |
| 25 | |
| 26 | --- |
| 27 | acinclude.m4 | 8 +------- |
| 28 | include/libunwind_i.h | 1 + |
| 29 | 2 files changed, 2 insertions(+), 7 deletions(-) |
| 30 | |
| 31 | diff --git a/acinclude.m4 b/acinclude.m4 |
| 32 | index 497f7c2..9c15af1 100644 |
| 33 | --- a/acinclude.m4 |
| 34 | +++ b/acinclude.m4 |
| 35 | @@ -22,11 +22,5 @@ fi]) |
| 36 | AC_DEFUN([CHECK_ATOMIC_OPS], |
| 37 | [dnl Check whether the system has the atomic_ops package installed. |
| 38 | AC_CHECK_HEADERS(atomic_ops.h) |
| 39 | -# |
| 40 | -# Don't link against libatomic_ops for now. We don't want libunwind |
| 41 | -# to depend on libatomic_ops.so. Fortunately, none of the platforms |
| 42 | -# we care about so far need libatomic_ops.a (everything is done via |
| 43 | -# inline macros). |
| 44 | -# |
| 45 | -# AC_CHECK_LIB(atomic_ops, main) |
| 46 | + AC_CHECK_LIB(atomic_ops, main) |
| 47 | ]) |
| 48 | diff --git a/include/libunwind_i.h b/include/libunwind_i.h |
| 49 | index 23f615e..deabdfd 100644 |
| 50 | --- a/include/libunwind_i.h |
| 51 | +++ b/include/libunwind_i.h |
| 52 | @@ -95,6 +95,7 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ |
| 53 | (pthread_mutex_unlock != NULL ? pthread_mutex_unlock (l) : 0) |
| 54 | |
| 55 | #ifdef HAVE_ATOMIC_OPS_H |
| 56 | +# define AO_REQUIRE_CAS |
| 57 | # include <atomic_ops.h> |
| 58 | static inline int |
| 59 | cmpxchg_ptr (void *addr, void *old, void *new) |
| 60 | -- |
| 61 | 1.9.2 |
| 62 | |