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Consolidate off_t/off64_t syscall argument passing

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This patch add three new macros (SYSCALL_LL, SYSCALL_LL64, and
__ASSUME_WORDSIZE64_ILP32) to use along with off_t and off64_t argument
syscalls.  The rationale for this change is:

1. Remove multiple implementations for the same syscall for different
   architectures (for instance, pread have 6 different implementations).

2. Also remove the requirement to use syscall wrappers for cancellable
   entrypoints.

The macro usage should be used along __ALIGNMENT_ARG to follow ABI constrains
for architecture where it applies.  For instance, pread can be rewritten as:

  return SYSCALL_CANCEL (pread, fd, buf, count,
                         __ALIGNMENT_ARG SYSCALL_LL (offset));

Another macro, SYSCALL_LL64, is provided for off64_t.  The macro
__ASSUME_WORDSIZE64_ILP32 is used by the ABI to define is uses 64-bit register
even if ABI is ILP32 (for instance x32 and mips64-n32).

The changes itself are not currently used in any implementation, so no
code change is expected.

	* sysdeps/unix/sysv/linux/generic/sysdep.h (__ALIGNMENT_ARG): Move
	definition.
	(__ALIGNMENT_COUNT): Likewise.
	* sysdeps/unix/sysv/linux/sysdep.h (__ALIGNMENT_ARG): To here.
	(__ALIGNMENT_COUNT): Likewise.
	(SYSCALL_LL): New define.
	(SYSCALL_LL64): Likewise.
	* sysdeps/unix/sysv/linux/mips/kernel-features.h:
	[_MIPS_SIM == _ABIO32] (__ASSUME_WORDSIZE64_ILP32): Define.
	* sysdeps/unix/sysv/linux/x86_64/kernel-features.h:
	[ILP32] (__ASUME_WORDSIZE64_ILP32): Likewise.
This commit is contained in:
Adhemerval Zanella
2015-10-21 10:04:07 -02:00
committed by Adhemerval Zanella
parent 482b2f87a8
commit eeddfa91cb
5 changed files with 47 additions and 10 deletions
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23
sysdeps/unix/sysv/linux/sysdep.h
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@ -15,6 +15,8 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <bits/wordsize.h>
/* Set error number and return -1. A target may choose to return the
internal function, __syscall_error, which sets errno and returns -1.
We use -1l, instead of -1, so that it can be casted to (void *). */
@ -23,3 +25,24 @@
__set_errno (err); \
-1l; \
})
/* Provide a dummy argument that can be used to force register
alignment for register pairs if required by the syscall ABI. */
#ifdef __ASSUME_ALIGNED_REGISTER_PAIRS
#define __ALIGNMENT_ARG 0,
#define __ALIGNMENT_COUNT(a,b) b
#else
#define __ALIGNMENT_ARG
#define __ALIGNMENT_COUNT(a,b) a
#endif
/* Provide a common macro to pass 64-bit value on syscalls. */
#if __WORDSIZE == 64 || defined __ASSUME_WORDSIZE64_ILP32
# define SYSCALL_LL(val) (val)
# define SYSCALL_LL64(val) (val)
#else
#define SYSCALL_LL(val) \
__LONG_LONG_PAIR ((val) >> 31, (val))
#define SYSCALL_LL64(val) \
__LONG_LONG_PAIR ((long) ((val) >> 32), (long) ((val) & 0xffffffff))
#endif