1 /* SPDX-License-Identifier: LGPL-2.1 OR MIT */
4  * Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu>
18  *   - WARNING! there's always a delayed slot!
19  *   - WARNING again, the syntax is different, registers take a '$' and numbers
21  *   - registers are 32-bit
22  *   - stack is 8-byte aligned
23  *   - syscall number is passed in v0 (starts at 0xfa0).
24  *   - arguments are in a0, a1, a2, a3, then the stack. The caller needs to
26  *   - Many registers are clobbered, in fact only a0..a2 and s0..s8 are
27  *     preserved. See: https://www.linux-mips.org/wiki/Syscall as well as
28  *     scall32-o32.S in the kernel sources.
29  *   - the system call is performed by calling "syscall"
30  *   - syscall return comes in v0, and register a3 needs to be checked to know
32  *   - the arguments are cast to long and assigned into the target registers
41 #define my_syscall0(num)                                                      \  argument
43 	register long _num __asm__ ("v0") = (num);                            \
47 		"addiu $sp, $sp, -32\n"                                       \
54 	_arg4 ? -_num : _num;                                                 \
57 #define my_syscall1(num, arg1)                                                \  argument
59 	register long _num __asm__ ("v0") = (num);                            \
64 		"addiu $sp, $sp, -32\n"                                       \
72 	_arg4 ? -_num : _num;                                                 \
75 #define my_syscall2(num, arg1, arg2)                                          \  argument
77 	register long _num __asm__ ("v0") = (num);                            \
83 		"addiu $sp, $sp, -32\n"                                       \
91 	_arg4 ? -_num : _num;                                                 \
94 #define my_syscall3(num, arg1, arg2, arg3)                                    \  argument
96 	register long _num __asm__ ("v0")  = (num);                           \
103 		"addiu $sp, $sp, -32\n"                                       \
111 	_arg4 ? -_num : _num;                                                 \
114 #define my_syscall4(num, arg1, arg2, arg3, arg4)                              \  argument
116 	register long _num __asm__ ("v0") = (num);                            \
123 		"addiu $sp, $sp, -32\n"                                       \
131 	_arg4 ? -_num : _num;                                                 \
134 #define my_syscall5(num, arg1, arg2, arg3, arg4, arg5)                        \  argument
136 	register long _num __asm__ ("v0") = (num);                            \
144 		"addiu $sp, $sp, -32\n"                                       \
153 	_arg4 ? -_num : _num;                                                 \
156 #define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6)                  \  argument
158 	register long _num __asm__ ("v0")  = (num);                           \
167 		"addiu $sp, $sp, -32\n"                                       \
178 	_arg4 ? -_num : _num;                                                 \
192 		"addiu $sp, $sp, -4\n"   /* space for .cprestore to store $gp              */  in __start()
194 		"li    $t0, -8\n"  in __start()
195 		"and   $sp, $sp, $t0\n"  /* $sp must be 8-byte aligned                     */  in __start()
196 		"addiu $sp, $sp, -16\n"  /* the callee expects to save a0..a3 there        */  in __start()