This is an automated email from the git hooks/post-receive script. It was generated because a ref change was pushed to the repository containing the project "uClibc-ng - small C library for embedded systems". The branch, master has been updated via 3ac3d4e61a1de0c2d0e0d2bebf0d1b111f153f12 (commit) from 95174cb69c523a1544e5f6f20e47f7d60007e569 (commit) Those revisions listed above that are new to this repository have not appeared on any other notification email; so we list those revisions in full, below. - Log ----------------------------------------------------------------- commit 3ac3d4e61a1de0c2d0e0d2bebf0d1b111f153f12 Author: Waldemar Brodkorb <wbx@openadk.org> Date: Tue May 31 20:51:29 2016 +0200 arm: add non-assembly versions of pthread_spin_lock/pthread_spin_trylock Sync pthread_spin_lock/pthread_spin_trylock with GNU libc as it avoids any usage of deprecated SWP instruction. This allows to build uClibc-ng for ARMv8 Cortex-A53 CPU in 32 Bit mode. ----------------------------------------------------------------------- Summary of changes: libpthread/nptl/sysdeps/arm/pthread_spin_lock.S | 30 ---------- libpthread/nptl/sysdeps/arm/pthread_spin_lock.c | 66 ++++++++++++++++++++++ libpthread/nptl/sysdeps/arm/pthread_spin_trylock.S | 33 ----------- .../sysdeps/{sparc => arm}/pthread_spin_trylock.c | 9 ++- 4 files changed, 70 insertions(+), 68 deletions(-) delete mode 100644 libpthread/nptl/sysdeps/arm/pthread_spin_lock.S create mode 100644 libpthread/nptl/sysdeps/arm/pthread_spin_lock.c delete mode 100644 libpthread/nptl/sysdeps/arm/pthread_spin_trylock.S copy libpthread/nptl/sysdeps/{sparc => arm}/pthread_spin_trylock.c (77%) diff --git a/libpthread/nptl/sysdeps/arm/pthread_spin_lock.S b/libpthread/nptl/sysdeps/arm/pthread_spin_lock.S deleted file mode 100644 index a9c07c8..0000000 --- a/libpthread/nptl/sysdeps/arm/pthread_spin_lock.S +++ /dev/null @@ -1,30 +0,0 @@ -/* Copyright (C) 2005 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, see - <http://www.gnu.org/licenses/>. */ - -#include <sysdep.h> - - .text - .align 4 - -ENTRY (pthread_spin_lock) - mov r1, #1 -1: swp r2, r1, [r0] - teq r2, #0 - bne 1b - mov r0, #0 - PSEUDO_RET_NOERRNO -END (pthread_spin_lock) diff --git a/libpthread/nptl/sysdeps/arm/pthread_spin_lock.c b/libpthread/nptl/sysdeps/arm/pthread_spin_lock.c new file mode 100644 index 0000000..77f5f50 --- /dev/null +++ b/libpthread/nptl/sysdeps/arm/pthread_spin_lock.c @@ -0,0 +1,66 @@ +/* pthread_spin_lock -- lock a spin lock. Generic version. + Copyright (C) 2012-2016 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, see + <http://www.gnu.org/licenses/>. */ + +#include <atomic.h> +#include "pthreadP.h" + +/* A machine-specific version can define SPIN_LOCK_READS_BETWEEN_CMPXCHG + to the number of plain reads that it's optimal to spin on between uses + of atomic_compare_and_exchange_val_acq. If spinning forever is optimal + then use -1. If no plain reads here would ever be optimal, use 0. */ +#define SPIN_LOCK_READS_BETWEEN_CMPXCHG 1000 + +int +pthread_spin_lock (pthread_spinlock_t *lock) +{ + /* atomic_exchange usually takes less instructions than + atomic_compare_and_exchange. On the other hand, + atomic_compare_and_exchange potentially generates less bus traffic + when the lock is locked. + We assume that the first try mostly will be successful, and we use + atomic_exchange. For the subsequent tries we use + atomic_compare_and_exchange. */ + if (atomic_exchange_acq (lock, 1) == 0) + return 0; + + do + { + /* The lock is contended and we need to wait. Going straight back + to cmpxchg is not a good idea on many targets as that will force + expensive memory synchronizations among processors and penalize other + running threads. + On the other hand, we do want to update memory state on the local core + once in a while to avoid spinning indefinitely until some event that + will happen to update local memory as a side-effect. */ + if (SPIN_LOCK_READS_BETWEEN_CMPXCHG >= 0) + { + int wait = SPIN_LOCK_READS_BETWEEN_CMPXCHG; + + while (*lock != 0 && wait > 0) + --wait; + } + else + { + while (*lock != 0) + ; + } + } + while (atomic_compare_and_exchange_val_acq (lock, 1, 0) != 0); + + return 0; +} diff --git a/libpthread/nptl/sysdeps/arm/pthread_spin_trylock.S b/libpthread/nptl/sysdeps/arm/pthread_spin_trylock.S deleted file mode 100644 index 8ccaffd..0000000 --- a/libpthread/nptl/sysdeps/arm/pthread_spin_trylock.S +++ /dev/null @@ -1,33 +0,0 @@ -/* Copyright (C) 2005 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, see - <http://www.gnu.org/licenses/>. */ - -#define _ERRNO_H 1 -#include <bits/errno.h> - -#include <sysdep.h> - - .text - .align 4 - -ENTRY (pthread_spin_trylock) - mov r1, #1 - swp r2, r1, [r0] - teq r2, #0 - moveq r0, #0 - movne r0, #EBUSY - PSEUDO_RET_NOERRNO -END (pthread_spin_trylock) diff --git a/libpthread/nptl/sysdeps/sparc/pthread_spin_trylock.c b/libpthread/nptl/sysdeps/arm/pthread_spin_trylock.c similarity index 77% copy from libpthread/nptl/sysdeps/sparc/pthread_spin_trylock.c copy to libpthread/nptl/sysdeps/arm/pthread_spin_trylock.c index c1b7b23..4e1a96c 100644 --- a/libpthread/nptl/sysdeps/sparc/pthread_spin_trylock.c +++ b/libpthread/nptl/sysdeps/arm/pthread_spin_trylock.c @@ -1,6 +1,6 @@ -/* Copyright (C) 2003 Free Software Foundation, Inc. +/* pthread_spin_trylock -- trylock a spin lock. Generic version. + Copyright (C) 2012-2016 Free Software Foundation, Inc. This file is part of the GNU C Library. - Contributed by Jakub Jelinek <jakub@redhat.com>, 2003. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public @@ -17,12 +17,11 @@ <http://www.gnu.org/licenses/>. */ #include <errno.h> +#include <atomic.h> #include "pthreadP.h" int pthread_spin_trylock (pthread_spinlock_t *lock) { - int res; - __asm__ __volatile__ ("ldstub [%1], %0" : "=r" (res) : "r" (lock) : "memory"); - return res == 0 ? 0 : EBUSY; + return atomic_exchange_acq (lock, 1) ? EBUSY : 0; } hooks/post-receive -- uClibc-ng - small C library for embedded systems