/* Copyright (C) 1996 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 <features.h> #include <sys/regdef.h> #include <asm/pal.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) * * syscall_number = the index of the system call we're invoking * arg1-arg5 = up to 5 integer arguments to the system call * * We need to do some arg shifting: the kernel expects the * syscall number in v0 and the first five args in a0-a4. * */ .globl __syscall; .align 4; .ent __syscall, 0; __syscall: .frame sp, 0, ra .prologue 0 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 call_pal PAL_callsys /* Invoke system call */ bne a3, $error ret $error: br gp, 2f 2: ldgp gp, 0(gp) jmp zero,__syscall_error .end __syscall weak_alias (__syscall, syscall)