1 /* $NetBSD: syscall.c,v 1.51 2023/10/05 19:41:04 ad Exp $ */
2
3 /*-
4 * Copyright (c) 2001 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe and by Charles M. Hannum.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 /*
33 * Copyright (c) 1988 University of Utah.
34 * Copyright (c) 1992, 1993
35 * The Regents of the University of California. All rights reserved.
36 *
37 * This code is derived from software contributed to Berkeley by
38 * the Systems Programming Group of the University of Utah Computer
39 * Science Department and Ralph Campbell.
40 *
41 * Redistribution and use in source and binary forms, with or without
42 * modification, are permitted provided that the following conditions
43 * are met:
44 * 1. Redistributions of source code must retain the above copyright
45 * notice, this list of conditions and the following disclaimer.
46 * 2. Redistributions in binary form must reproduce the above copyright
47 * notice, this list of conditions and the following disclaimer in the
48 * documentation and/or other materials provided with the distribution.
49 * 3. Neither the name of the University nor the names of its contributors
50 * may be used to endorse or promote products derived from this software
51 * without specific prior written permission.
52 *
53 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
54 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
55 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
56 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
57 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
58 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
59 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
60 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
61 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
62 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
63 * SUCH DAMAGE.
64 *
65 * from: Utah Hdr: trap.c 1.32 91/04/06
66 *
67 * @(#)trap.c 8.5 (Berkeley) 1/11/94
68 */
69
70 #include <sys/cdefs.h>
71 __KERNEL_RCSID(0, "$NetBSD: syscall.c,v 1.51 2023/10/05 19:41:04 ad Exp $");
72
73 #include <sys/param.h>
74 #include <sys/cpu.h>
75 #include <sys/endian.h>
76 #include <sys/proc.h>
77 #include <sys/signal.h>
78 #include <sys/syscall.h>
79 #include <sys/syscallvar.h>
80 #include <sys/systm.h>
81
82 #include <uvm/uvm_extern.h>
83
84 #include <mips/locore.h>
85 #include <mips/trap.h>
86 #include <mips/reg.h>
87 #include <mips/regnum.h> /* symbolic register indices */
88 #include <mips/userret.h>
89
90 #ifndef EMULNAME
91 #define EMULNAME(x) (x)
92 #endif
93
94 #ifndef SYSCALL_SHIFT
95 #define SYSCALL_SHIFT 0
96 #endif
97
98 void EMULNAME(syscall_intern)(struct proc *);
99 static void EMULNAME(syscall)(struct lwp *, uint32_t, uint32_t, vaddr_t);
100
101 void
EMULNAME(syscall_intern)102 EMULNAME(syscall_intern)(struct proc *p)
103 {
104 p->p_md.md_syscall = EMULNAME(syscall);
105 }
106
107 /*
108 * Process a system call.
109 *
110 * System calls are strange beasts. They are passed the syscall number
111 * in v0, and the arguments in the registers (as normal). They return
112 * an error flag in a3 (if a3 != 0 on return, the syscall had an error),
113 * and the return value (if any) in v0 and possibly v1.
114 */
115
116 void
EMULNAME(syscall)117 EMULNAME(syscall)(struct lwp *l, u_int status, u_int cause, vaddr_t pc)
118 {
119 struct proc *p = l->l_proc;
120 struct trapframe *tf = l->l_md.md_utf;
121 struct reg *reg = &tf->tf_registers;
122 mips_reg_t *fargs = ®->r_regs[_R_A0];
123 register_t *args = NULL;
124 register_t copyargs[2+SYS_MAXSYSARGS];
125 vaddr_t usp;
126 size_t nargs;
127 const struct sysent *callp;
128 int code, error;
129 #if defined(__mips_o32)
130 const int abi = _MIPS_BSD_API_O32;
131 KASSERTMSG(p->p_md.md_abi == abi,
132 "pid %d(%p): md_abi(%d) != abi(%d)",
133 p->p_pid, p, p->p_md.md_abi, abi);
134 size_t nregs = 4;
135 #else
136 const int abi = p->p_md.md_abi;
137 size_t nregs = _MIPS_SIM_NEWABI_P(abi) ? 8 : 4;
138 size_t i;
139 #endif
140
141 curcpu()->ci_data.cpu_nsyscall++;
142
143 if (cause & MIPS_CR_BR_DELAY)
144 reg->r_regs[_R_PC] = mips_emul_branch(tf, pc, 0, false);
145 else
146 reg->r_regs[_R_PC] = pc + sizeof(uint32_t);
147
148 callp = p->p_emul->e_sysent;
149 const mips_reg_t saved_v0 = reg->r_regs[_R_V0];
150 code = saved_v0 - SYSCALL_SHIFT;
151
152 if (code == SYS_syscall
153 || (code == SYS___syscall && abi != _MIPS_BSD_API_O32)) {
154 /*
155 * Code is first argument, followed by actual args.
156 */
157 code = *fargs++ - SYSCALL_SHIFT;
158 nregs--;
159 } else if (code == SYS___syscall) {
160 /*
161 * Like syscall, but code is a quad, so as to maintain
162 * quad alignment for the rest of the arguments.
163 */
164 code = fargs[_QUAD_LOWWORD] - SYSCALL_SHIFT;
165 fargs += 2;
166 nregs -= 2;
167 }
168
169 if (code >= p->p_emul->e_nsysent)
170 callp += p->p_emul->e_nosys;
171 else
172 callp += code;
173
174 nargs = callp->sy_narg;
175 #if !defined(__mips_o32)
176 if (abi != _MIPS_BSD_API_O32) {
177 #endif
178 CTASSERT(sizeof(copyargs[0]) == sizeof(fargs[0]));
179 if (nargs <= nregs) {
180 /*
181 * Just use the trapframe for the source of arguments
182 */
183 args = fargs;
184 } else {
185 const size_t nsaved = _MIPS_SIM_NEWABI_P(abi) ? 0 : 4;
186 KASSERT(nargs <= __arraycount(copyargs));
187 args = copyargs;
188 /*
189 * Copy the arguments passed via register from the
190 * trapframe to our argument array
191 */
192 memcpy(copyargs, fargs, nregs * sizeof(register_t));
193 /*
194 * Start copying args skipping the register slots
195 * slots on the stack.
196 */
197 usp = reg->r_regs[_R_SP] + nsaved * sizeof(register_t);
198 error = copyin((register_t *)usp, ©args[nregs],
199 (nargs - nregs) * sizeof(copyargs[0]));
200 if (error)
201 goto bad;
202 }
203 #if !defined(__mips_o32)
204 } else do {
205 /*
206 * The only difference between O32 and N32 is the calling
207 * sequence. If you make O32
208 */
209 int32_t copy32args[SYS_MAXSYSARGS];
210 int32_t *cargs = copy32args;
211 unsigned int arg64mask = SYCALL_ARG_64_MASK(callp);
212 bool doing_arg64;
213 size_t narg64 = SYCALL_NARGS64(callp);
214 /*
215 * All arguments are 32bits wide and 64bit arguments use
216 * two 32bit registers or stack slots. We need to remarshall
217 * them into 64bit slots
218 */
219 args = copyargs;
220 CTASSERT(sizeof(copy32args[0]) != sizeof(fargs[0]));
221
222 /*
223 * If there are no 64bit arguments and all arguments were in
224 * registers, just use the trapframe for the source of arguments
225 */
226 if (nargs <= nregs && narg64 == 0) {
227 args = fargs;
228 break;
229 }
230
231 if (nregs <= nargs + narg64) {
232 /*
233 * Grab the non-register arguments from the stack
234 * after skipping the slots for the 4 register passed
235 * arguments.
236 */
237 usp = reg->r_regs[_R_SP] + 4 * sizeof(int32_t);
238 error = copyin((int32_t *)usp, copy32args,
239 (nargs + narg64 - nregs) * sizeof(copy32args[0]));
240 if (error)
241 goto bad;
242 }
243 /*
244 * Copy all the arguments to copyargs, starting with the ones
245 * in registers. Using the hints in the 64bit argmask,
246 * we marshall the passed 32bit values into 64bit slots. If we
247 * encounter a 64 bit argument, we grab two adjacent 32bit
248 * values and synthesize the 64bit argument.
249 */
250 for (i = 0, doing_arg64 = false; i < nargs + narg64;) {
251 register_t arg;
252 if (nregs > 0) {
253 arg = (int32_t) *fargs++;
254 nregs--;
255 } else {
256 arg = *cargs++;
257 }
258 if (__predict_true((arg64mask & 1) == 0)) {
259 /*
260 * Just copy it with sign extension on
261 */
262 copyargs[i++] = (int32_t) arg;
263 arg64mask >>= 1;
264 continue;
265 }
266 /*
267 * 64bit arg. grab the low 32 bits, discard the high.
268 */
269 arg = (uint32_t)arg;
270 if (!doing_arg64) {
271 /*
272 * Pick up the 1st word of a 64bit arg.
273 * If lowword == 1 then highword == 0,
274 * so this is the highword and thus
275 * shifted left by 32, otherwise
276 * lowword == 0 and highword == 1 so
277 * it isn't shifted at all. Remember
278 * we still need another word.
279 */
280 doing_arg64 = true;
281 copyargs[i] = arg << (_QUAD_LOWWORD*32);
282 narg64--; /* one less 64bit arg */
283 } else {
284 /*
285 * Pick up the 2nd word of a 64bit arg.
286 * if highword == 1, it's shifted left
287 * by 32, otherwise lowword == 1 and
288 * highword == 0 so it isn't shifted at
289 * all. And now head to the next argument.
290 */
291 doing_arg64 = false;
292 copyargs[i++] |= arg << (_QUAD_HIGHWORD*32);
293 arg64mask >>= 1;
294 }
295 }
296 } while (/*CONSTCOND*/ 0); /* avoid a goto */
297 #endif
298
299 #ifdef MIPS_SYSCALL_DEBUG
300 if (p->p_emul->e_syscallnames)
301 printf("syscall %s:", p->p_emul->e_syscallnames[code]);
302 else
303 printf("syscall %u:", code);
304 if (nargs == 0)
305 printf(" <no args>");
306 else for (size_t j = 0; j < nargs; j++) {
307 if (j == nregs) printf(" *");
308 printf(" [%s%zu]=%#"PRIxREGISTER,
309 SYCALL_ARG_64_P(callp, j) ? "+" : "",
310 j, args[j]);
311 }
312 printf("\n");
313 #endif
314
315 error = sy_invoke(callp, l, args, ®->r_regs[_R_V0], code);
316
317 switch (error) {
318 case 0:
319 #if !defined(__mips_o32)
320 if (abi == _MIPS_BSD_API_O32 && SYCALL_RET_64_P(callp)) {
321 /*
322 * If this is from O32 and it's a 64bit quantity,
323 * split it into 2 32bit values in adjacent registers.
324 */
325 mips_reg_t tmp = reg->r_regs[_R_V0];
326 reg->r_regs[_R_V0 + _QUAD_LOWWORD] = (int32_t) tmp;
327 reg->r_regs[_R_V0 + _QUAD_HIGHWORD] = tmp >> 32;
328 }
329 #endif
330 #ifdef MIPS_SYSCALL_DEBUG
331 if (p->p_emul->e_syscallnames)
332 printf("syscall %s:", p->p_emul->e_syscallnames[code]);
333 else
334 printf("syscall %u:", code);
335 printf(" return v0=%#"PRIxREGISTER" v1=%#"PRIxREGISTER"\n",
336 reg->r_regs[_R_V0], reg->r_regs[_R_V1]);
337 #endif
338 reg->r_regs[_R_A3] = 0;
339 break;
340 case ERESTART:
341 reg->r_regs[_R_V0] = saved_v0; /* restore syscall code */
342 reg->r_regs[_R_PC] = pc;
343 break;
344 case EJUSTRETURN:
345 break; /* nothing to do */
346 default:
347 bad:
348 if (p->p_emul->e_errno)
349 error = p->p_emul->e_errno[error];
350 reg->r_regs[_R_V0] = error;
351 reg->r_regs[_R_A3] = 1;
352 #ifdef MIPS_SYSCALL_DEBUG
353 if (p->p_emul->e_syscallnames)
354 printf("syscall %s:", p->p_emul->e_syscallnames[code]);
355 else
356 printf("syscall %u:", code);
357 printf(" return error=%d\n", error);
358 #endif
359 break;
360 }
361
362 KASSERT(l->l_blcnt == 0);
363 KASSERT(curcpu()->ci_biglock_count == 0);
364
365 userret(l);
366 }
367