[PATCH v2] m68k: Enforce 4-byte alignment on internal locks (BZ #29537)

[Andreas K. Huettel]

Works fine for me too.

Tested-by: Andreas K. Huettel <dilfridge@gentoo.org>

Am Montag, 5. September 2022, 19:10:43 CEST schrieb Adhemerval Zanella:
> A new internal definition, __LIBC_LOCK_ALIGNMENT, is used to force
> the 4-byte alignment only for m68k, other architecture keep the
> natural alignment of the type used internally (and hppa does not
> require 16-byte alignment for kernel-assisted CAS).
> ---
>  sysdeps/generic/libc-lock-arch.h              | 25 +++++++++++++++++++
>  sysdeps/nptl/libc-lock.h                      |  8 +++++-
>  sysdeps/nptl/libc-lockP.h                     |  3 ++-
>  sysdeps/unix/sysv/linux/m68k/libc-lock-arch.h | 25 +++++++++++++++++++
>  4 files changed, 59 insertions(+), 2 deletions(-)
>  create mode 100644 sysdeps/generic/libc-lock-arch.h
>  create mode 100644 sysdeps/unix/sysv/linux/m68k/libc-lock-arch.h
> 
> diff --git a/sysdeps/generic/libc-lock-arch.h b/sysdeps/generic/libc-lock-arch.h
> new file mode 100644
> index 0000000000..4713b30a8a
> --- /dev/null
> +++ b/sysdeps/generic/libc-lock-arch.h
> @@ -0,0 +1,25 @@
> +/* Private libc-internal arch-specific definitions.  Generic version.
> +   Copyright (C) 2022 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; see the file COPYING.LIB.  If
> +   not, see <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef _LIBC_LOCK_ARCH_H
> +#define _LIBC_LOCK_ARCH_H
> +
> +/* The default definition uses the natural alignment from the lock type.  */
> +#define __LIBC_LOCK_ALIGNMENT
> +
> +#endif
> diff --git a/sysdeps/nptl/libc-lock.h b/sysdeps/nptl/libc-lock.h
> index 5af476c48b..63b3f3d75c 100644
> --- a/sysdeps/nptl/libc-lock.h
> +++ b/sysdeps/nptl/libc-lock.h
> @@ -22,6 +22,7 @@
>  #include <pthread.h>
>  #define __need_NULL
>  #include <stddef.h>
> +#include <libc-lock-arch.h>
>  
>  
>  /* Mutex type.  */
> @@ -29,7 +30,12 @@
>  # if (!IS_IN (libc) && !IS_IN (libpthread)) || !defined _LIBC
>  typedef struct { pthread_mutex_t mutex; } __libc_lock_recursive_t;
>  # else
> -typedef struct { int lock; int cnt; void *owner; } __libc_lock_recursive_t;
> +typedef struct
> +{
> +  int lock __LIBC_LOCK_ALIGNMENT;
> +  int cnt;
> +  void *owner;
> +} __libc_lock_recursive_t;
>  # endif
>  #else
>  typedef struct __libc_lock_recursive_opaque__ __libc_lock_recursive_t;
> diff --git a/sysdeps/nptl/libc-lockP.h b/sysdeps/nptl/libc-lockP.h
> index d3a6837fd2..425f514c5c 100644
> --- a/sysdeps/nptl/libc-lockP.h
> +++ b/sysdeps/nptl/libc-lockP.h
> @@ -32,9 +32,10 @@
>     ld.so might be used on old kernels with a different libc.so.  */
>  #include <lowlevellock.h>
>  #include <tls.h>
> +#include <libc-lock-arch.h>
>  
>  /* Mutex type.  */
> -typedef int __libc_lock_t;
> +typedef int __libc_lock_t __LIBC_LOCK_ALIGNMENT;
>  typedef struct { pthread_mutex_t mutex; } __rtld_lock_recursive_t;
>  typedef pthread_rwlock_t __libc_rwlock_t;
>  
> diff --git a/sysdeps/unix/sysv/linux/m68k/libc-lock-arch.h b/sysdeps/unix/sysv/linux/m68k/libc-lock-arch.h
> new file mode 100644
> index 0000000000..1844bbaf6f
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/m68k/libc-lock-arch.h
> @@ -0,0 +1,25 @@
> +/* Private libc-internal arch-specific definitions.  m68k version.
> +   Copyright (C) 2022 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; see the file COPYING.LIB.  If
> +   not, see <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef _LIBC_LOCK_ARCH_H
> +#define _LIBC_LOCK_ARCH_H
> +
> +/* Linux enforces 4-bytes alignment on futex inputs.  */
> +#define __LIBC_LOCK_ALIGNMENT __attribute__ ((__aligned__ (4)))
> +
> +#endif
> 


-- 
Andreas K. Hüttel
dilfridge@gentoo.org
Gentoo Linux developer 
(council, qa, toolchain, base-system, perl, libreoffice)
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