1 /* SPDX-License-Identifier: LGPL-2.1 OR MIT */
2 /*
3  * RISCV (32 and 64) specific definitions for NOLIBC
4  * Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu>
5  */
6 
7 #ifndef _NOLIBC_ARCH_RISCV_H
8 #define _NOLIBC_ARCH_RISCV_H
9 
10 /* O_* macros for fcntl/open are architecture-specific */
11 #define O_RDONLY            0
12 #define O_WRONLY            1
13 #define O_RDWR              2
14 #define O_CREAT         0x100
15 #define O_EXCL          0x200
16 #define O_NOCTTY        0x400
17 #define O_TRUNC        0x1000
18 #define O_APPEND       0x2000
19 #define O_NONBLOCK     0x4000
20 #define O_DIRECTORY  0x200000
21 
22 struct sys_stat_struct {
23 	unsigned long	st_dev;		/* Device.  */
24 	unsigned long	st_ino;		/* File serial number.  */
25 	unsigned int	st_mode;	/* File mode.  */
26 	unsigned int	st_nlink;	/* Link count.  */
27 	unsigned int	st_uid;		/* User ID of the file's owner.  */
28 	unsigned int	st_gid;		/* Group ID of the file's group. */
29 	unsigned long	st_rdev;	/* Device number, if device.  */
30 	unsigned long	__pad1;
31 	long		st_size;	/* Size of file, in bytes.  */
32 	int		st_blksize;	/* Optimal block size for I/O.  */
33 	int		__pad2;
34 	long		st_blocks;	/* Number 512-byte blocks allocated. */
35 	long		st_atime;	/* Time of last access.  */
36 	unsigned long	st_atime_nsec;
37 	long		st_mtime;	/* Time of last modification.  */
38 	unsigned long	st_mtime_nsec;
39 	long		st_ctime;	/* Time of last status change.  */
40 	unsigned long	st_ctime_nsec;
41 	unsigned int	__unused4;
42 	unsigned int	__unused5;
43 };
44 
45 #if   __riscv_xlen == 64
46 #define PTRLOG "3"
47 #define SZREG  "8"
48 #elif __riscv_xlen == 32
49 #define PTRLOG "2"
50 #define SZREG  "4"
51 #endif
52 
53 /* Syscalls for RISCV :
54  *   - stack is 16-byte aligned
55  *   - syscall number is passed in a7
56  *   - arguments are in a0, a1, a2, a3, a4, a5
57  *   - the system call is performed by calling ecall
58  *   - syscall return comes in a0
59  *   - the arguments are cast to long and assigned into the target
60  *     registers which are then simply passed as registers to the asm code,
61  *     so that we don't have to experience issues with register constraints.
62  *
63  * On riscv, select() is not implemented so we have to use pselect6().
64  */
65 #define __ARCH_WANT_SYS_PSELECT6
66 
67 #define my_syscall0(num)                                                      \
68 ({                                                                            \
69 	register long _num  __asm__ ("a7") = (num);                           \
70 	register long _arg1 __asm__ ("a0");                                   \
71 									      \
72 	__asm__  volatile (                                                   \
73 		"ecall\n\t"                                                   \
74 		: "=r"(_arg1)                                                 \
75 		: "r"(_num)                                                   \
76 		: "memory", "cc"                                              \
77 	);                                                                    \
78 	_arg1;                                                                \
79 })
80 
81 #define my_syscall1(num, arg1)                                                \
82 ({                                                                            \
83 	register long _num  __asm__ ("a7") = (num);                           \
84 	register long _arg1 __asm__ ("a0") = (long)(arg1);		      \
85 									      \
86 	__asm__  volatile (                                                   \
87 		"ecall\n"                                                     \
88 		: "+r"(_arg1)                                                 \
89 		: "r"(_num)                                                   \
90 		: "memory", "cc"                                              \
91 	);                                                                    \
92 	_arg1;                                                                \
93 })
94 
95 #define my_syscall2(num, arg1, arg2)                                          \
96 ({                                                                            \
97 	register long _num  __asm__ ("a7") = (num);                           \
98 	register long _arg1 __asm__ ("a0") = (long)(arg1);                    \
99 	register long _arg2 __asm__ ("a1") = (long)(arg2);                    \
100 									      \
101 	__asm__  volatile (                                                   \
102 		"ecall\n"                                                     \
103 		: "+r"(_arg1)                                                 \
104 		: "r"(_arg2),                                                 \
105 		  "r"(_num)                                                   \
106 		: "memory", "cc"                                              \
107 	);                                                                    \
108 	_arg1;                                                                \
109 })
110 
111 #define my_syscall3(num, arg1, arg2, arg3)                                    \
112 ({                                                                            \
113 	register long _num  __asm__ ("a7") = (num);                           \
114 	register long _arg1 __asm__ ("a0") = (long)(arg1);                    \
115 	register long _arg2 __asm__ ("a1") = (long)(arg2);                    \
116 	register long _arg3 __asm__ ("a2") = (long)(arg3);                    \
117 									      \
118 	__asm__  volatile (                                                   \
119 		"ecall\n\t"                                                   \
120 		: "+r"(_arg1)                                                 \
121 		: "r"(_arg2), "r"(_arg3),                                     \
122 		  "r"(_num)                                                   \
123 		: "memory", "cc"                                              \
124 	);                                                                    \
125 	_arg1;                                                                \
126 })
127 
128 #define my_syscall4(num, arg1, arg2, arg3, arg4)                              \
129 ({                                                                            \
130 	register long _num  __asm__ ("a7") = (num);                           \
131 	register long _arg1 __asm__ ("a0") = (long)(arg1);                    \
132 	register long _arg2 __asm__ ("a1") = (long)(arg2);                    \
133 	register long _arg3 __asm__ ("a2") = (long)(arg3);                    \
134 	register long _arg4 __asm__ ("a3") = (long)(arg4);                    \
135 									      \
136 	__asm__  volatile (                                                   \
137 		"ecall\n"                                                     \
138 		: "+r"(_arg1)                                                 \
139 		: "r"(_arg2), "r"(_arg3), "r"(_arg4),                         \
140 		  "r"(_num)                                                   \
141 		: "memory", "cc"                                              \
142 	);                                                                    \
143 	_arg1;                                                                \
144 })
145 
146 #define my_syscall5(num, arg1, arg2, arg3, arg4, arg5)                        \
147 ({                                                                            \
148 	register long _num  __asm__ ("a7") = (num);                           \
149 	register long _arg1 __asm__ ("a0") = (long)(arg1);                    \
150 	register long _arg2 __asm__ ("a1") = (long)(arg2);                    \
151 	register long _arg3 __asm__ ("a2") = (long)(arg3);                    \
152 	register long _arg4 __asm__ ("a3") = (long)(arg4);                    \
153 	register long _arg5 __asm__ ("a4") = (long)(arg5);                    \
154 									      \
155 	__asm__  volatile (                                                   \
156 		"ecall\n"                                                     \
157 		: "+r"(_arg1)                                                 \
158 		: "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5),             \
159 		  "r"(_num)                                                   \
160 		: "memory", "cc"                                              \
161 	);                                                                    \
162 	_arg1;                                                                \
163 })
164 
165 #define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6)                  \
166 ({                                                                            \
167 	register long _num  __asm__ ("a7") = (num);                           \
168 	register long _arg1 __asm__ ("a0") = (long)(arg1);                    \
169 	register long _arg2 __asm__ ("a1") = (long)(arg2);                    \
170 	register long _arg3 __asm__ ("a2") = (long)(arg3);                    \
171 	register long _arg4 __asm__ ("a3") = (long)(arg4);                    \
172 	register long _arg5 __asm__ ("a4") = (long)(arg5);                    \
173 	register long _arg6 __asm__ ("a5") = (long)(arg6);                    \
174 									      \
175 	__asm__  volatile (                                                   \
176 		"ecall\n"                                                     \
177 		: "+r"(_arg1)                                                 \
178 		: "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), "r"(_arg6), \
179 		  "r"(_num)                                                   \
180 		: "memory", "cc"                                              \
181 	);                                                                    \
182 	_arg1;                                                                \
183 })
184 
185 /* startup code */
186 __asm__ (".section .text\n"
187     ".weak _start\n"
188     "_start:\n"
189     ".option push\n"
190     ".option norelax\n"
191     "lla   gp, __global_pointer$\n"
192     ".option pop\n"
193     "lw    a0, 0(sp)\n"          // argc (a0) was in the stack
194     "add   a1, sp, "SZREG"\n"    // argv (a1) = sp
195     "slli  a2, a0, "PTRLOG"\n"   // envp (a2) = SZREG*argc ...
196     "add   a2, a2, "SZREG"\n"    //             + SZREG (skip null)
197     "add   a2,a2,a1\n"           //             + argv
198     "andi  sp,a1,-16\n"          // sp must be 16-byte aligned
199     "call  main\n"               // main() returns the status code, we'll exit with it.
200     "li a7, 93\n"                // NR_exit == 93
201     "ecall\n"
202     "");
203 
204 #endif // _NOLIBC_ARCH_RISCV_H
205