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 struct sys_stat_struct {
11 unsigned long st_dev; /* Device. */
12 unsigned long st_ino; /* File serial number. */
13 unsigned int st_mode; /* File mode. */
14 unsigned int st_nlink; /* Link count. */
15 unsigned int st_uid; /* User ID of the file's owner. */
16 unsigned int st_gid; /* Group ID of the file's group. */
17 unsigned long st_rdev; /* Device number, if device. */
18 unsigned long __pad1;
19 long st_size; /* Size of file, in bytes. */
20 int st_blksize; /* Optimal block size for I/O. */
21 int __pad2;
22 long st_blocks; /* Number 512-byte blocks allocated. */
23 long st_atime; /* Time of last access. */
24 unsigned long st_atime_nsec;
25 long st_mtime; /* Time of last modification. */
26 unsigned long st_mtime_nsec;
27 long st_ctime; /* Time of last status change. */
28 unsigned long st_ctime_nsec;
29 unsigned int __unused4;
30 unsigned int __unused5;
31 };
32
33 #if __riscv_xlen == 64
34 #define PTRLOG "3"
35 #define SZREG "8"
36 #elif __riscv_xlen == 32
37 #define PTRLOG "2"
38 #define SZREG "4"
39 #endif
40
41 /* Syscalls for RISCV :
42 * - stack is 16-byte aligned
43 * - syscall number is passed in a7
44 * - arguments are in a0, a1, a2, a3, a4, a5
45 * - the system call is performed by calling ecall
46 * - syscall return comes in a0
47 * - the arguments are cast to long and assigned into the target
48 * registers which are then simply passed as registers to the asm code,
49 * so that we don't have to experience issues with register constraints.
50 *
51 * On riscv, select() is not implemented so we have to use pselect6().
52 */
53 #define __ARCH_WANT_SYS_PSELECT6
54
55 #define my_syscall0(num) \
56 ({ \
57 register long _num __asm__ ("a7") = (num); \
58 register long _arg1 __asm__ ("a0"); \
59 \
60 __asm__ volatile ( \
61 "ecall\n\t" \
62 : "=r"(_arg1) \
63 : "r"(_num) \
64 : "memory", "cc" \
65 ); \
66 _arg1; \
67 })
68
69 #define my_syscall1(num, arg1) \
70 ({ \
71 register long _num __asm__ ("a7") = (num); \
72 register long _arg1 __asm__ ("a0") = (long)(arg1); \
73 \
74 __asm__ volatile ( \
75 "ecall\n" \
76 : "+r"(_arg1) \
77 : "r"(_num) \
78 : "memory", "cc" \
79 ); \
80 _arg1; \
81 })
82
83 #define my_syscall2(num, arg1, arg2) \
84 ({ \
85 register long _num __asm__ ("a7") = (num); \
86 register long _arg1 __asm__ ("a0") = (long)(arg1); \
87 register long _arg2 __asm__ ("a1") = (long)(arg2); \
88 \
89 __asm__ volatile ( \
90 "ecall\n" \
91 : "+r"(_arg1) \
92 : "r"(_arg2), \
93 "r"(_num) \
94 : "memory", "cc" \
95 ); \
96 _arg1; \
97 })
98
99 #define my_syscall3(num, arg1, arg2, arg3) \
100 ({ \
101 register long _num __asm__ ("a7") = (num); \
102 register long _arg1 __asm__ ("a0") = (long)(arg1); \
103 register long _arg2 __asm__ ("a1") = (long)(arg2); \
104 register long _arg3 __asm__ ("a2") = (long)(arg3); \
105 \
106 __asm__ volatile ( \
107 "ecall\n\t" \
108 : "+r"(_arg1) \
109 : "r"(_arg2), "r"(_arg3), \
110 "r"(_num) \
111 : "memory", "cc" \
112 ); \
113 _arg1; \
114 })
115
116 #define my_syscall4(num, arg1, arg2, arg3, arg4) \
117 ({ \
118 register long _num __asm__ ("a7") = (num); \
119 register long _arg1 __asm__ ("a0") = (long)(arg1); \
120 register long _arg2 __asm__ ("a1") = (long)(arg2); \
121 register long _arg3 __asm__ ("a2") = (long)(arg3); \
122 register long _arg4 __asm__ ("a3") = (long)(arg4); \
123 \
124 __asm__ volatile ( \
125 "ecall\n" \
126 : "+r"(_arg1) \
127 : "r"(_arg2), "r"(_arg3), "r"(_arg4), \
128 "r"(_num) \
129 : "memory", "cc" \
130 ); \
131 _arg1; \
132 })
133
134 #define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
135 ({ \
136 register long _num __asm__ ("a7") = (num); \
137 register long _arg1 __asm__ ("a0") = (long)(arg1); \
138 register long _arg2 __asm__ ("a1") = (long)(arg2); \
139 register long _arg3 __asm__ ("a2") = (long)(arg3); \
140 register long _arg4 __asm__ ("a3") = (long)(arg4); \
141 register long _arg5 __asm__ ("a4") = (long)(arg5); \
142 \
143 __asm__ volatile ( \
144 "ecall\n" \
145 : "+r"(_arg1) \
146 : "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
147 "r"(_num) \
148 : "memory", "cc" \
149 ); \
150 _arg1; \
151 })
152
153 #define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
154 ({ \
155 register long _num __asm__ ("a7") = (num); \
156 register long _arg1 __asm__ ("a0") = (long)(arg1); \
157 register long _arg2 __asm__ ("a1") = (long)(arg2); \
158 register long _arg3 __asm__ ("a2") = (long)(arg3); \
159 register long _arg4 __asm__ ("a3") = (long)(arg4); \
160 register long _arg5 __asm__ ("a4") = (long)(arg5); \
161 register long _arg6 __asm__ ("a5") = (long)(arg6); \
162 \
163 __asm__ volatile ( \
164 "ecall\n" \
165 : "+r"(_arg1) \
166 : "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), "r"(_arg6), \
167 "r"(_num) \
168 : "memory", "cc" \
169 ); \
170 _arg1; \
171 })
172
173 char **environ __attribute__((weak));
174 const unsigned long *_auxv __attribute__((weak));
175
176 /* startup code */
_start(void)177 void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void)
178 {
179 __asm__ volatile (
180 ".option push\n"
181 ".option norelax\n"
182 "lla gp, __global_pointer$\n"
183 ".option pop\n"
184 "lw a0, 0(sp)\n" // argc (a0) was in the stack
185 "add a1, sp, "SZREG"\n" // argv (a1) = sp
186 "slli a2, a0, "PTRLOG"\n" // envp (a2) = SZREG*argc ...
187 "add a2, a2, "SZREG"\n" // + SZREG (skip null)
188 "add a2,a2,a1\n" // + argv
189
190 "add a3, a2, zero\n" // iterate a3 over envp to find auxv (after NULL)
191 "0:\n" // do {
192 "ld a4, 0(a3)\n" // a4 = *a3;
193 "add a3, a3, "SZREG"\n" // a3 += sizeof(void*);
194 "bne a4, zero, 0b\n" // } while (a4);
195 "lui a4, %hi(_auxv)\n" // a4 = &_auxv (high bits)
196 "sd a3, %lo(_auxv)(a4)\n" // store a3 into _auxv
197
198 "lui a3, %hi(environ)\n" // a3 = &environ (high bits)
199 "sd a2,%lo(environ)(a3)\n" // store envp(a2) into environ
200 "andi sp,a1,-16\n" // sp must be 16-byte aligned
201 "call main\n" // main() returns the status code, we'll exit with it.
202 "li a7, 93\n" // NR_exit == 93
203 "ecall\n"
204 );
205 __builtin_unreachable();
206 }
207
208 #endif // _NOLIBC_ARCH_RISCV_H
209