1 /* $NetBSD: syscall.c,v 1.26 2023/04/03 17:58:41 gutteridge Exp $ */
2
3 /*-
4 * Copyright (c) 2007 Jared D. McNeill <jmcneill@invisible.ca>
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 __KERNEL_RCSID(0, "$NetBSD: syscall.c,v 1.26 2023/04/03 17:58:41 gutteridge Exp $");
31
32 #include <sys/types.h>
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/proc.h>
36 #include <sys/lwp.h>
37 #include <sys/sched.h>
38 #include <sys/ktrace.h>
39 #include <sys/syscall.h>
40 #include <sys/syscallvar.h>
41 #include <sys/syscallargs.h>
42
43 #include <sys/userret.h>
44 #include <machine/pcb.h>
45 #include <machine/thunk.h>
46 #include <machine/machdep.h>
47
48 void
md_child_return(struct lwp * l)49 md_child_return(struct lwp *l)
50 {
51 register_t rval[2];
52 struct pcb *pcb = lwp_getpcb(l);
53 ucontext_t *ucp = &pcb->pcb_userret_ucp;
54
55 /* return value zero */
56 rval[0] = 0;
57 rval[1] = 0;
58 md_syscall_set_returnargs(l, ucp, 0, rval);
59
60 aprint_debug("child return! lwp %p\n", l);
61 userret(l);
62 }
63
64 /*
65 * Process the tail end of a posix_spawn() for the child.
66 */
67 void
cpu_spawn_return(struct lwp * l)68 cpu_spawn_return(struct lwp *l)
69 {
70
71 userret(l);
72 }
73
74 extern const char *const syscallnames[];
75
76 static void syscall_args_print(lwp_t *l, int code, int nargs, int argsize,
77 register_t *args);
78 static void syscall_retvals_print(lwp_t *l, lwp_t *clwp,
79 int code, int nargs, register_t *args, int error, register_t *rval);
80
81
82 void
syscall(void)83 syscall(void)
84 {
85 lwp_t *l = curlwp;
86 const struct proc * const p = l->l_proc;
87 const struct sysent *callp;
88 struct pcb *pcb = lwp_getpcb(l);
89 ucontext_t *ucp = &pcb->pcb_userret_ucp;
90 register_t copyargs[2+SYS_MAXSYSARGS];
91 register_t *args;
92 register_t rval[2];
93 uint32_t code, opcode;
94 uint nargs, argsize;
95 int error;
96
97 /* system call accounting */
98 curcpu()->ci_data.cpu_nsyscall++;
99 LWP_CACHE_CREDS(l, l->l_proc);
100
101 /* XXX do we want do do emulation? */
102 md_syscall_get_opcode(ucp, &opcode);
103 md_syscall_get_syscallnumber(ucp, &code);
104 code &= (SYS_NSYSENT -1);
105
106 callp = p->p_emul->e_sysent + code;
107 nargs = callp->sy_narg;
108 argsize = callp->sy_argsize;
109
110 args = copyargs;
111 rval[0] = rval[1] = 0;
112 error = md_syscall_getargs(l, ucp, nargs, argsize, args);
113
114 #if 0
115 aprint_debug("syscall no. %d, ", code);
116 aprint_debug("nargs %d, argsize %d => ", nargs, argsize);
117 thunk_printf_debug("syscall no. %d, ", code);
118 thunk_printf_debug("nargs %d, argsize %d => ", nargs, argsize);
119 #endif
120
121 /*
122 * TODO change the pre and post printing into functions so they can be
123 * easily adjusted and dont clobber up this space
124 */
125
126 if (!error)
127 syscall_args_print(l, code, nargs, argsize, args);
128
129 md_syscall_inc_pc(ucp, opcode);
130
131 if (!error) {
132 error = sy_invoke(callp, l, args, rval, code);
133 }
134
135 syscall_retvals_print(l, curlwp, code, nargs, args, error, rval);
136
137 //out:
138 switch (error) {
139 default:
140 /* FALLTHROUGH */
141 case 0:
142 md_syscall_set_returnargs(l, ucp, error, rval);
143 /* FALLTHROUGH */
144 case EJUSTRETURN:
145 break;
146 case ERESTART:
147 md_syscall_dec_pc(ucp, opcode);
148 /* nothing to do */
149 break;
150 }
151 //thunk_printf_debug("end of syscall : return to userland\n");
152 //if (code != 4) thunk_printf("userret() code %d\n", code);
153 }
154
155
156 static void
syscall_args_print(lwp_t * l,int code,int nargs,int argsize,register_t * args)157 syscall_args_print(lwp_t *l, int code, int nargs, int argsize, register_t *args)
158 {
159 char **argv, **envp;
160
161 return;
162 if (code != 4) {
163 thunk_printf("lwp %p, code %3d, nargs %d, argsize %3d\t%s(",
164 l, code, nargs, argsize, syscallnames[code]);
165 switch (code) {
166 case 5:
167 thunk_printf("\"%s\", %"PRIx32", %"PRIx32"", (char *) (args[0]), (uint) args[1], (uint) args[2]);
168 break;
169 case 33:
170 thunk_printf("\"%s\", %"PRIx32"", (char *) (args[0]), (uint) args[1]);
171 break;
172 case 50:
173 thunk_printf("\"%s\"", (char *) (args[0]));
174 break;
175 case 58:
176 thunk_printf("\"%s\", %"PRIx32", %"PRIx32"", (char *) (args[0]), (uint) (args[1]), (uint) args[2]);
177 break;
178 case 59:
179 thunk_printf("\"%s\", [", (char *) (args[0]));
180 argv = (char **) (args[1]);
181 if (*argv) {
182 while (*argv) {
183 thunk_printf("\"%s\", ", *argv);
184 argv++;
185 }
186 thunk_printf("\b\b");
187 }
188 thunk_printf("], [");
189 envp = (char **) (args[2]);
190 if (*envp) {
191 while (*envp) {
192 thunk_printf("\"%s\", ", *envp);
193 envp++;
194 }
195 thunk_printf("\b\b");
196 }
197 thunk_printf("]");
198 break;
199 default:
200 for (int i = 0; i < nargs; i++)
201 thunk_printf("%"PRIx32", ", (uint) args[i]);
202 if (nargs)
203 thunk_printf("\b\b");
204 }
205 thunk_printf(") ");
206 }
207 #if 0
208 if ((code == 4)) {
209 // thunk_printf_debug("[us] %s", (char *) args[1]);
210 thunk_printf("[us] %s", (char *) args[1]);
211 }
212 #endif
213 }
214
215
216 static void
syscall_retvals_print(lwp_t * l,lwp_t * clwp,int code,int nargs,register_t * args,int error,register_t * rval)217 syscall_retvals_print(lwp_t *l, lwp_t *clwp, int code, int nargs, register_t *args, int error, register_t *rval)
218 {
219 char const *errstr;
220
221 return;
222 switch (error) {
223 case EJUSTRETURN:
224 errstr = "EJUSTRETURN";
225 break;
226 case EAGAIN:
227 errstr = "EGAIN";
228 break;
229 default:
230 errstr = "OK";
231 }
232 if (code != 4)
233 thunk_printf("=> %s: %d, (%"PRIx32", %"PRIx32")\n",
234 errstr, error, (uint) (rval[0]), (uint) (rval[1]));
235 }
236