diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/alpha/syscall.S')
| -rw-r--r-- | sysdeps/unix/sysv/linux/alpha/syscall.S | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/alpha/syscall.S b/sysdeps/unix/sysv/linux/alpha/syscall.S new file mode 100644 index 0000000000..b0088e5eca --- /dev/null +++ b/sysdeps/unix/sysv/linux/alpha/syscall.S @@ -0,0 +1,70 @@ +/* Copyright (C) 1996-2014 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by David Mosberger <davidm@azstarnet.com>, 1996. + + 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> + +/* + * This is for COMPATIBILITY with Linux/x86 only. Linux/Alpha system + * calls return an error indication in a3. This allows arbitrary 64bit + * values to be returned in v0 (because negative values are not + * mistaken as error numbers). However, C allows only one value to + * be returned, so the interface below folds the error indication passed in + * a3 back into v0: it sets v0 to -errno if an error occurs. Thus, + * no negative 64bit numbers can be returned. To avoid this problem, + * use assembly stubs wherever possible/convenient. + * + * Usage: + * + * long syscall(syscall_number, arg1, arg2, arg3, arg4, arg5, arg6) + * + * syscall_number = the index of the system call we're invoking + * arg1-arg6 = up to 6 integer arguments to the system call + * + * We need to do some arg shifting: the kernel expects the + * syscall number in v0 and the first six args in a0-a5. + * + */ + + +LEAF(__syscall, 0) +#ifdef PROF + ldgp gp, 0(pv) + .set noat + lda AT, _mcount + jsr AT, (AT), _mcount + .set at + .prologue 1 +#else + .prologue 0 +#endif + + mov a0, v0 /* Syscall number -> v0 */ + mov a1, a0 /* arg1-arg5 -> a0-a4 */ + mov a2, a1 + mov a3, a2 + mov a4, a3 + mov a5, a4 + ldq a5,0(sp) /* arg6 -> a5 */ + + call_pal PAL_callsys /* Invoke system call */ + bne a3, SYSCALL_ERROR_LABEL + ret + +PSEUDO_END(__syscall) + +weak_alias (__syscall, syscall) |