execregs.c revision 1.1.4.2 1 /* $NetBSD: execregs.c,v 1.1.4.2 2025/08/02 05:58:02 perseant Exp $ */
2
3 /*-
4 * Copyright (c) 2025 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __RCSID("$NetBSD: execregs.c,v 1.1.4.2 2025/08/02 05:58:02 perseant Exp $");
31
32 #include "execregs.h"
33
34 #include <errno.h>
35 #include <spawn.h>
36 #include <stddef.h>
37 #include <unistd.h>
38
39 extern char **environ;
40
41 static unsigned long
42 nonnull(unsigned long x)
43 {
44
45 x |= x << 8;
46 x |= x << 16;
47 x |= x << 32;
48 return x;
49 }
50
51 int
52 execregschild(char *path)
53 {
54 /* x0: used to pass exec arg0, nonnull anyway (path) */
55 /* x1: used to pass exec arg1, nonnull anyway (argv) */
56 /* x2: used to pass exec arg2, nonnull anyway (environ) */
57 register long x3 __asm("x3") = nonnull(3);
58 register long x4 __asm("x4") = nonnull(4);
59 register long x5 __asm("x5") = nonnull(5);
60 register long x6 __asm("x6") = nonnull(6);
61 register long x7 __asm("x7") = nonnull(7);
62 register long x8 __asm("x8") = nonnull(8);
63 register long x9 __asm("x9") = nonnull(9);
64 register long x10 __asm("x10") = nonnull(10);
65 register long x11 __asm("x11") = nonnull(11);
66 register long x12 __asm("x12") = nonnull(12);
67 register long x13 __asm("x13") = nonnull(13);
68 register long x14 __asm("x14") = nonnull(14);
69 register long x15 __asm("x15") = nonnull(15);
70 register long x16 __asm("x16") = nonnull(16);
71 register long x17 __asm("x17") = nonnull(17);
72 register long x18 __asm("x18") = nonnull(18);
73 register long x19 __asm("x19") = nonnull(19);
74 register long x20 __asm("x20") = nonnull(20);
75 register long x21 __asm("x21") = nonnull(21);
76 register long x22 __asm("x22") = nonnull(22);
77 register long x23 __asm("x23") = nonnull(23);
78 register long x24 __asm("x24") = nonnull(24);
79 register long x25 __asm("x25") = nonnull(25);
80 register long x26 __asm("x26") = nonnull(26);
81 register long x27 __asm("x27") = nonnull(27);
82 register long x28 __asm("x28") = nonnull(28);
83 /* x29: frame pointer, nonnull anyway */
84 /* x30: link register, nonnull anyway */
85
86 char *argv[] = {path, NULL};
87 char **envp = environ;
88
89 /*
90 * Not perfect -- compiler might use some registers for
91 * stack/argument transfers, but all the arguments are nonnull
92 * so this is probably a good test anyway.
93 */
94 __asm volatile("" :
95 "+r"(x3),
96 "+r"(x4),
97 "+r"(x5),
98 "+r"(x6),
99 "+r"(x7),
100 "+r"(x8),
101 "+r"(x9),
102 "+r"(x10),
103 "+r"(x11),
104 "+r"(x12),
105 "+r"(x13),
106 "+r"(x14),
107 "+r"(x15),
108 "+r"(x16),
109 "+r"(x17)
110 :: "memory");
111 /* pacify gcc error: more than 30 operands in 'asm' */
112 __asm volatile("" :
113 "+r"(x18),
114 "+r"(x19),
115 "+r"(x20),
116 "+r"(x21),
117 "+r"(x22),
118 "+r"(x23),
119 "+r"(x24),
120 "+r"(x25),
121 "+r"(x26),
122 "+r"(x27),
123 "+r"(x28)
124 :: "memory");
125
126 return execve(path, argv, envp);
127 }
128
129 pid_t
130 spawnregschild(char *path, int fd)
131 {
132 /* x0: used to pass posix_spawn arg0, nonnull anyway (&pid) */
133 /* x1: used to pass posix_spawn arg1, nonnull anyway (path) */
134 /* x2: used to pass posix_spawn arg2, nonnull anyway (&fileacts) */
135 /* x3: used to pass posix_spawn arg3, nonnull anyway (&attr) */
136 /* x4: used to pass posix_spawn arg3, nonnull anyway (argv) */
137 /* x5: used to pass posix_spawn arg3, nonnull anyway (environ) */
138 register long x6 __asm("x6") = nonnull(6);
139 register long x7 __asm("x7") = nonnull(7);
140 register long x8 __asm("x8") = nonnull(8);
141 register long x9 __asm("x9") = nonnull(9);
142 register long x10 __asm("x10") = nonnull(10);
143 register long x11 __asm("x11") = nonnull(11);
144 register long x12 __asm("x12") = nonnull(12);
145 register long x13 __asm("x13") = nonnull(13);
146 register long x14 __asm("x14") = nonnull(14);
147 register long x15 __asm("x15") = nonnull(15);
148 register long x16 __asm("x16") = nonnull(16);
149 register long x17 __asm("x17") = nonnull(17);
150 register long x18 __asm("x18") = nonnull(18);
151 register long x19 __asm("x19") = nonnull(19);
152 register long x20 __asm("x20") = nonnull(20);
153 register long x21 __asm("x21") = nonnull(21);
154 register long x22 __asm("x22") = nonnull(22);
155 register long x23 __asm("x23") = nonnull(23);
156 register long x24 __asm("x24") = nonnull(24);
157 register long x25 __asm("x25") = nonnull(25);
158 register long x26 __asm("x26") = nonnull(26);
159 register long x27 __asm("x27") = nonnull(27);
160 register long x28 __asm("x28") = nonnull(28);
161 /* x29: frame pointer, nonnull anyway */
162 /* x30: link register, nonnull anyway */
163
164 char *argv[] = {path, NULL};
165 char **envp = environ;
166 posix_spawn_file_actions_t fileacts;
167 posix_spawnattr_t attr;
168 pid_t pid;
169 int error;
170
171 error = posix_spawn_file_actions_init(&fileacts);
172 if (error)
173 goto out;
174 error = posix_spawn_file_actions_adddup2(&fileacts, fd, STDOUT_FILENO);
175 if (error)
176 goto out;
177 error = posix_spawnattr_init(&attr);
178 if (error)
179 goto out;
180
181 /*
182 * Not perfect -- compiler might use some registers for
183 * stack/argument transfers, but all the arguments are nonnull
184 * so this is probably a good test anyway.
185 */
186 __asm volatile("" :
187 "+r"(x6),
188 "+r"(x7),
189 "+r"(x8),
190 "+r"(x9),
191 "+r"(x10),
192 "+r"(x11),
193 "+r"(x12),
194 "+r"(x13),
195 "+r"(x14),
196 "+r"(x15),
197 "+r"(x16),
198 "+r"(x17),
199 "+r"(x18),
200 "+r"(x19),
201 "+r"(x20)
202 :: "memory");
203 /* pacify gcc error: more than 30 operands in 'asm' */
204 __asm volatile("" :
205 "+r"(x21),
206 "+r"(x22),
207 "+r"(x23),
208 "+r"(x24),
209 "+r"(x25),
210 "+r"(x26),
211 "+r"(x27),
212 "+r"(x28)
213 :: "memory");
214
215 error = posix_spawn(&pid, path, &fileacts, &attr, argv, envp);
216 if (error)
217 goto out;
218
219 out: posix_spawnattr_destroy(&attr);
220 posix_spawn_file_actions_destroy(&fileacts);
221 if (error) {
222 errno = error;
223 return -1;
224 }
225 return 0;
226 }
227