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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/arch/alpha/kernel/signal.c
4 *
5 * Copyright (C) 1995 Linus Torvalds
6 *
7 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 */
9
10#include <linux/sched/signal.h>
11#include <linux/sched/task_stack.h>
12#include <linux/kernel.h>
13#include <linux/signal.h>
14#include <linux/errno.h>
15#include <linux/wait.h>
16#include <linux/ptrace.h>
17#include <linux/unistd.h>
18#include <linux/mm.h>
19#include <linux/smp.h>
20#include <linux/stddef.h>
21#include <linux/tty.h>
22#include <linux/binfmts.h>
23#include <linux/bitops.h>
24#include <linux/syscalls.h>
25#include <linux/resume_user_mode.h>
26
27#include <linux/uaccess.h>
28#include <asm/sigcontext.h>
29#include <asm/ucontext.h>
30#include <linux/entry-common.h>
31#include "proto.h"
32
33#define DEBUG_SIG 0
34
35#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
36
37asmlinkage void ret_from_sys_call(void);
38
39/*
40 * The OSF/1 sigprocmask calling sequence is different from the
41 * C sigprocmask() sequence..
42 */
43SYSCALL_DEFINE2(osf_sigprocmask, int, how, unsigned long, newmask)
44{
45 sigset_t oldmask;
46 sigset_t mask;
47 unsigned long res;
48
49 siginitset(&mask, newmask & _BLOCKABLE);
50 res = sigprocmask(how, &mask, &oldmask);
51 if (!res) {
52 force_successful_syscall_return();
53 res = oldmask.sig[0];
54 }
55 return res;
56}
57
58SYSCALL_DEFINE3(osf_sigaction, int, sig,
59 const struct osf_sigaction __user *, act,
60 struct osf_sigaction __user *, oact)
61{
62 struct k_sigaction new_ka, old_ka;
63 int ret;
64
65 if (act) {
66 old_sigset_t mask;
67 if (!access_ok(act, sizeof(*act)) ||
68 __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
69 __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
70 __get_user(mask, &act->sa_mask))
71 return -EFAULT;
72 siginitset(&new_ka.sa.sa_mask, mask);
73 new_ka.ka_restorer = NULL;
74 }
75
76 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
77
78 if (!ret && oact) {
79 if (!access_ok(oact, sizeof(*oact)) ||
80 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
81 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
82 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
83 return -EFAULT;
84 }
85
86 return ret;
87}
88
89SYSCALL_DEFINE5(rt_sigaction, int, sig, const struct sigaction __user *, act,
90 struct sigaction __user *, oact,
91 size_t, sigsetsize, void __user *, restorer)
92{
93 struct k_sigaction new_ka, old_ka;
94 int ret;
95
96 /* XXX: Don't preclude handling different sized sigset_t's. */
97 if (sigsetsize != sizeof(sigset_t))
98 return -EINVAL;
99
100 if (act) {
101 new_ka.ka_restorer = restorer;
102 if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
103 return -EFAULT;
104 }
105
106 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
107
108 if (!ret && oact) {
109 if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
110 return -EFAULT;
111 }
112
113 return ret;
114}
115
116/*
117 * Do a signal return; undo the signal stack.
118 */
119
120#if _NSIG_WORDS > 1
121# error "Non SA_SIGINFO frame needs rearranging"
122#endif
123
124struct sigframe
125{
126 struct sigcontext sc;
127 unsigned int retcode[3];
128};
129
130struct rt_sigframe
131{
132 struct siginfo info;
133 struct ucontext uc;
134 unsigned int retcode[3];
135};
136
137/* If this changes, userland unwinders that Know Things about our signal
138 frame will break. Do not undertake lightly. It also implies an ABI
139 change wrt the size of siginfo_t, which may cause some pain. */
140extern char compile_time_assert
141 [offsetof(struct rt_sigframe, uc.uc_mcontext) == 176 ? 1 : -1];
142
143#define INSN_MOV_R30_R16 0x47fe0410
144#define INSN_LDI_R0 0x201f0000
145#define INSN_CALLSYS 0x00000083
146
147static long
148restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
149{
150 unsigned long usp;
151 struct switch_stack *sw = (struct switch_stack *)regs - 1;
152 long err = __get_user(regs->pc, &sc->sc_pc);
153
154 current->restart_block.fn = do_no_restart_syscall;
155 current_thread_info()->status |= TS_SAVED_FP | TS_RESTORE_FP;
156
157 sw->r26 = (unsigned long) ret_from_sys_call;
158
159 err |= __get_user(regs->r0, sc->sc_regs+0);
160 err |= __get_user(regs->r1, sc->sc_regs+1);
161 err |= __get_user(regs->r2, sc->sc_regs+2);
162 err |= __get_user(regs->r3, sc->sc_regs+3);
163 err |= __get_user(regs->r4, sc->sc_regs+4);
164 err |= __get_user(regs->r5, sc->sc_regs+5);
165 err |= __get_user(regs->r6, sc->sc_regs+6);
166 err |= __get_user(regs->r7, sc->sc_regs+7);
167 err |= __get_user(regs->r8, sc->sc_regs+8);
168 err |= __get_user(sw->r9, sc->sc_regs+9);
169 err |= __get_user(sw->r10, sc->sc_regs+10);
170 err |= __get_user(sw->r11, sc->sc_regs+11);
171 err |= __get_user(sw->r12, sc->sc_regs+12);
172 err |= __get_user(sw->r13, sc->sc_regs+13);
173 err |= __get_user(sw->r14, sc->sc_regs+14);
174 err |= __get_user(sw->r15, sc->sc_regs+15);
175 err |= __get_user(regs->r16, sc->sc_regs+16);
176 err |= __get_user(regs->r17, sc->sc_regs+17);
177 err |= __get_user(regs->r18, sc->sc_regs+18);
178 err |= __get_user(regs->r19, sc->sc_regs+19);
179 err |= __get_user(regs->r20, sc->sc_regs+20);
180 err |= __get_user(regs->r21, sc->sc_regs+21);
181 err |= __get_user(regs->r22, sc->sc_regs+22);
182 err |= __get_user(regs->r23, sc->sc_regs+23);
183 err |= __get_user(regs->r24, sc->sc_regs+24);
184 err |= __get_user(regs->r25, sc->sc_regs+25);
185 err |= __get_user(regs->r26, sc->sc_regs+26);
186 err |= __get_user(regs->r27, sc->sc_regs+27);
187 err |= __get_user(regs->r28, sc->sc_regs+28);
188 err |= __get_user(regs->gp, sc->sc_regs+29);
189 err |= __get_user(usp, sc->sc_regs+30);
190 wrusp(usp);
191
192 err |= __copy_from_user(current_thread_info()->fp,
193 sc->sc_fpregs, 31 * 8);
194 err |= __get_user(current_thread_info()->fp[31], &sc->sc_fpcr);
195
196 return err;
197}
198
199/* Note that this syscall is also used by setcontext(3) to install
200 a given sigcontext. This because it's impossible to set *all*
201 registers and transfer control from userland. */
202
203asmlinkage void
204do_sigreturn(struct sigcontext __user *sc)
205{
206 struct pt_regs *regs = current_pt_regs();
207 sigset_t set;
208
209 /* Verify that it's a good sigcontext before using it */
210 if (!access_ok(sc, sizeof(*sc)))
211 goto give_sigsegv;
212 if (__get_user(set.sig[0], &sc->sc_mask))
213 goto give_sigsegv;
214
215 set_current_blocked(&set);
216
217 if (restore_sigcontext(sc, regs))
218 goto give_sigsegv;
219
220 /* Send SIGTRAP if we're single-stepping: */
221 if (ptrace_cancel_bpt (current)) {
222 send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
223 current);
224 }
225 return;
226
227give_sigsegv:
228 force_sig(SIGSEGV);
229}
230
231asmlinkage void
232do_rt_sigreturn(struct rt_sigframe __user *frame)
233{
234 struct pt_regs *regs = current_pt_regs();
235 sigset_t set;
236
237 /* Verify that it's a good ucontext_t before using it */
238 if (!access_ok(&frame->uc, sizeof(frame->uc)))
239 goto give_sigsegv;
240 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
241 goto give_sigsegv;
242
243 set_current_blocked(&set);
244
245 if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
246 goto give_sigsegv;
247
248 /* Send SIGTRAP if we're single-stepping: */
249 if (ptrace_cancel_bpt (current)) {
250 send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc,
251 current);
252 }
253 return;
254
255give_sigsegv:
256 force_sig(SIGSEGV);
257}
258
259
260/*
261 * Set up a signal frame.
262 */
263
264static inline void __user *
265get_sigframe(struct ksignal *ksig, unsigned long sp, size_t frame_size)
266{
267 return (void __user *)((sigsp(sp, ksig) - frame_size) & -32ul);
268}
269
270static long
271setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
272 unsigned long mask, unsigned long sp)
273{
274 struct switch_stack *sw = (struct switch_stack *)regs - 1;
275 long err = 0;
276
277 err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack);
278 err |= __put_user(mask, &sc->sc_mask);
279 err |= __put_user(regs->pc, &sc->sc_pc);
280 err |= __put_user(8, &sc->sc_ps);
281
282 err |= __put_user(regs->r0 , sc->sc_regs+0);
283 err |= __put_user(regs->r1 , sc->sc_regs+1);
284 err |= __put_user(regs->r2 , sc->sc_regs+2);
285 err |= __put_user(regs->r3 , sc->sc_regs+3);
286 err |= __put_user(regs->r4 , sc->sc_regs+4);
287 err |= __put_user(regs->r5 , sc->sc_regs+5);
288 err |= __put_user(regs->r6 , sc->sc_regs+6);
289 err |= __put_user(regs->r7 , sc->sc_regs+7);
290 err |= __put_user(regs->r8 , sc->sc_regs+8);
291 err |= __put_user(sw->r9 , sc->sc_regs+9);
292 err |= __put_user(sw->r10 , sc->sc_regs+10);
293 err |= __put_user(sw->r11 , sc->sc_regs+11);
294 err |= __put_user(sw->r12 , sc->sc_regs+12);
295 err |= __put_user(sw->r13 , sc->sc_regs+13);
296 err |= __put_user(sw->r14 , sc->sc_regs+14);
297 err |= __put_user(sw->r15 , sc->sc_regs+15);
298 err |= __put_user(regs->r16, sc->sc_regs+16);
299 err |= __put_user(regs->r17, sc->sc_regs+17);
300 err |= __put_user(regs->r18, sc->sc_regs+18);
301 err |= __put_user(regs->r19, sc->sc_regs+19);
302 err |= __put_user(regs->r20, sc->sc_regs+20);
303 err |= __put_user(regs->r21, sc->sc_regs+21);
304 err |= __put_user(regs->r22, sc->sc_regs+22);
305 err |= __put_user(regs->r23, sc->sc_regs+23);
306 err |= __put_user(regs->r24, sc->sc_regs+24);
307 err |= __put_user(regs->r25, sc->sc_regs+25);
308 err |= __put_user(regs->r26, sc->sc_regs+26);
309 err |= __put_user(regs->r27, sc->sc_regs+27);
310 err |= __put_user(regs->r28, sc->sc_regs+28);
311 err |= __put_user(regs->gp , sc->sc_regs+29);
312 err |= __put_user(sp, sc->sc_regs+30);
313 err |= __put_user(0, sc->sc_regs+31);
314
315 err |= __copy_to_user(sc->sc_fpregs,
316 current_thread_info()->fp, 31 * 8);
317 err |= __put_user(0, sc->sc_fpregs+31);
318 err |= __put_user(current_thread_info()->fp[31], &sc->sc_fpcr);
319
320 err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0);
321 err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1);
322 err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2);
323
324 return err;
325}
326
327static int
328setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
329{
330 unsigned long oldsp, r26, err = 0;
331 struct sigframe __user *frame;
332
333 oldsp = rdusp();
334 frame = get_sigframe(ksig, oldsp, sizeof(*frame));
335 if (!access_ok(frame, sizeof(*frame)))
336 return -EFAULT;
337
338 err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp);
339 if (err)
340 return -EFAULT;
341
342 /* Set up to return from userspace. If provided, use a stub
343 already in userspace. */
344 r26 = (unsigned long) ksig->ka.ka_restorer;
345 if (!r26) {
346 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
347 err |= __put_user(INSN_LDI_R0+__NR_sigreturn, frame->retcode+1);
348 err |= __put_user(INSN_CALLSYS, frame->retcode+2);
349 imb();
350 r26 = (unsigned long) frame->retcode;
351 }
352
353 /* Check that everything was written properly. */
354 if (err)
355 return err;
356
357 /* "Return" to the handler */
358 regs->r26 = r26;
359 regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
360 regs->r16 = ksig->sig; /* a0: signal number */
361 regs->r17 = 0; /* a1: exception code */
362 regs->r18 = (unsigned long) &frame->sc; /* a2: sigcontext pointer */
363 wrusp((unsigned long) frame);
364
365#if DEBUG_SIG
366 printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
367 current->comm, current->pid, frame, regs->pc, regs->r26);
368#endif
369 return 0;
370}
371
372static int
373setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
374{
375 unsigned long oldsp, r26, err = 0;
376 struct rt_sigframe __user *frame;
377
378 oldsp = rdusp();
379 frame = get_sigframe(ksig, oldsp, sizeof(*frame));
380 if (!access_ok(frame, sizeof(*frame)))
381 return -EFAULT;
382
383 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
384
385 /* Create the ucontext. */
386 err |= __put_user(0, &frame->uc.uc_flags);
387 err |= __put_user(0, &frame->uc.uc_link);
388 err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask);
389 err |= __save_altstack(&frame->uc.uc_stack, oldsp);
390 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs,
391 set->sig[0], oldsp);
392 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
393 if (err)
394 return -EFAULT;
395
396 /* Set up to return from userspace. If provided, use a stub
397 already in userspace. */
398 r26 = (unsigned long) ksig->ka.ka_restorer;
399 if (!r26) {
400 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
401 err |= __put_user(INSN_LDI_R0+__NR_rt_sigreturn,
402 frame->retcode+1);
403 err |= __put_user(INSN_CALLSYS, frame->retcode+2);
404 imb();
405 r26 = (unsigned long) frame->retcode;
406 }
407
408 if (err)
409 return -EFAULT;
410
411 /* "Return" to the handler */
412 regs->r26 = r26;
413 regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
414 regs->r16 = ksig->sig; /* a0: signal number */
415 regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */
416 regs->r18 = (unsigned long) &frame->uc; /* a2: ucontext pointer */
417 wrusp((unsigned long) frame);
418
419#if DEBUG_SIG
420 printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
421 current->comm, current->pid, frame, regs->pc, regs->r26);
422#endif
423
424 return 0;
425}
426
427
428/*
429 * OK, we're invoking a handler.
430 */
431static inline void
432handle_signal(struct ksignal *ksig, struct pt_regs *regs)
433{
434 sigset_t *oldset = sigmask_to_save();
435 int ret;
436
437 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
438 ret = setup_rt_frame(ksig, oldset, regs);
439 else
440 ret = setup_frame(ksig, oldset, regs);
441
442 signal_setup_done(ret, ksig, 0);
443}
444
445static inline void
446syscall_restart(unsigned long r0, unsigned long r19,
447 struct pt_regs *regs, struct k_sigaction *ka)
448{
449 switch (regs->r0) {
450 case ERESTARTSYS:
451 if (!(ka->sa.sa_flags & SA_RESTART)) {
452 case ERESTARTNOHAND:
453 regs->r0 = EINTR;
454 break;
455 }
456 fallthrough;
457 case ERESTARTNOINTR:
458 regs->r0 = r0; /* reset v0 and a3 and replay syscall */
459 regs->r1 = r0;
460 regs->r19 = r19;
461 regs->pc -= 4;
462 break;
463 case ERESTART_RESTARTBLOCK:
464 regs->r0 = EINTR;
465 break;
466 }
467}
468
469
470/*
471 * Note that 'init' is a special process: it doesn't get signals it doesn't
472 * want to handle. Thus you cannot kill init even with a SIGKILL even by
473 * mistake.
474 *
475 * Note that we go through the signals twice: once to check the signals that
476 * the kernel can handle, and then we build all the user-level signal handling
477 * stack-frames in one go after that.
478 *
479 * "r0" and "r19" are the registers we need to restore for system call
480 * restart. "r0" is also used as an indicator whether we can restart at
481 * all (if we get here from anything but a syscall return, it will be 0)
482 */
483void
484do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
485{
486 unsigned long single_stepping = ptrace_cancel_bpt(current);
487 struct ksignal ksig;
488
489 /* This lets the debugger run, ... */
490 if (get_signal(&ksig)) {
491 /* ... so re-check the single stepping. */
492 single_stepping |= ptrace_cancel_bpt(current);
493 /* Whee! Actually deliver the signal. */
494 if (r0)
495 syscall_restart(r0, r19, regs, &ksig.ka);
496 handle_signal(&ksig, regs);
497 } else {
498 single_stepping |= ptrace_cancel_bpt(current);
499 if (r0) {
500 switch (regs->r0) {
501 case ERESTARTNOHAND:
502 case ERESTARTSYS:
503 case ERESTARTNOINTR:
504 /* Reset v0 and a3 and replay syscall. */
505 regs->r0 = r0;
506 regs->r1 = r0;
507 regs->r19 = r19;
508 regs->pc -= 4;
509 break;
510 case ERESTART_RESTARTBLOCK:
511 /* Set v0 to the restart_syscall and replay */
512 regs->r0 = __NR_restart_syscall;
513 regs->r1 = __NR_restart_syscall;
514 regs->pc -= 4;
515 break;
516 }
517 }
518 restore_saved_sigmask();
519 }
520 if (single_stepping)
521 ptrace_set_bpt(current); /* re-set breakpoint */
522}
523
524asmlinkage void alpha_exit_to_user_mode(struct pt_regs *regs)
525{
526 local_irq_disable();
527 irqentry_exit_to_user_mode_prepare(regs);
528 exit_to_user_mode();
529}
530
531/*
532 * Syscall return reaches here after Alpha-specific r0/a3 result encoding.
533 * Delegate syscall-exit work and final exit-to-user handling to generic
534 * entry code; low-level PAL restore remains in assembly.
535 */
536asmlinkage void alpha_syscall_exit_to_user_mode(struct pt_regs *regs)
537{
538 syscall_exit_to_user_mode(regs);
539}
540
541void arch_do_signal_or_restart(struct pt_regs *regs)
542{
543 struct thread_info *ti = current_thread_info();
544
545 preempt_disable();
546 save_fpu();
547 preempt_enable();
548 do_signal(regs, ti->syscall_saved_nr, ti->syscall_saved_r19);
549}
550
551asmlinkage unsigned long
552alpha_syscall_enter_select(struct pt_regs *regs, long syscall)
553{
554 struct thread_info *ti = current_thread_info();
555 unsigned long saved_r0 = regs->r0;
556 unsigned long saved_r19 = regs->r19;
557 unsigned long fn = (unsigned long)sys_ni_syscall;
558 long nr = syscall;
559 bool permit;
560
561 ti->syscall_meta = 0;
562 ti->syscall_saved_nr = syscall;
563
564 if (!(ti->status & TS_SAVED_FP)) {
565 ti->status |= TS_SAVED_FP;
566 __save_fpu();
567 }
568
569 permit = syscall_enter_from_user_mode_randomize_stack(regs, &nr);
570
571 /*
572 * Alpha cannot preset the full -ENOSYS return state before generic
573 * entry handling, because r19 is still syscall argument 4 on the
574 * normal dispatch path. So provide the default -ENOSYS result only
575 * here, after we know no real syscall will be invoked, and only if
576 * entry work did not already change the return state.
577 */
578 if (unlikely(!permit || (unsigned long)nr >= NR_syscalls)) {
579 if (regs->r0 == saved_r0 && regs->r19 == saved_r19)
580 syscall_set_return_value(current, regs, -ENOSYS, 0);
581
582 ti->syscall_meta = ALPHA_SYSCALL_META_SKIP;
583 return fn; /* ignored by asm when SKIP is set */
584 }
585
586 instrumentation_begin();
587 {
588 unsigned long index;
589
590 index = array_index_nospec((unsigned long)nr, NR_syscalls);
591 fn = (unsigned long)sys_call_table[index];
592 }
593 instrumentation_end();
594
595 return fn;
596}
597
598asmlinkage noinstr void
599alpha_finish_syscall_to_user_mode(struct pt_regs *regs, long ret)
600{
601 struct thread_info *ti = current_thread_info();
602 unsigned long meta = ti->syscall_meta;
603
604 ti->syscall_meta = 0;
605 ti->syscall_saved_r19 = regs->r19;
606
607 instrumentation_begin();
608
609 if (meta & ALPHA_SYSCALL_META_SKIP) {
610 /*
611 * Skip-dispatch path: ptrace/seccomp may already have installed
612 * the return state in r0/r19. Preserve it unless the syscall was
613 * skipped with no explicit return value.
614 *
615 * Generic PTRACE_SET_SYSCALL_INFO changes only the syscall-number
616 * shadow, so r1 == -1 while r0 still contains the original Alpha
617 * syscall number. Legacy PTRACE_POKEUSR based skipping can leave
618 * r0 == -1 with a3/r19 still indicating success. Both represent
619 * an unhandled skipped syscall and should become ENOSYS/a3=1.
620 */
621 if (regs->r1 == (unsigned long)-1 &&
622 (regs->r0 == ti->syscall_saved_nr ||
623 regs->r0 == (unsigned long)-1)) {
624 regs->r0 = ENOSYS;
625 regs->r19 = 1;
626 }
627
628 instrumentation_end();
629
630 syscall_exit_to_user_mode(regs);
631 return;
632 }
633
634 /*
635 * Some successful syscalls, notably legacy ptrace PEEK requests,
636 * return arbitrary data in r0. That data may have the bit pattern
637 * of a negative errno, so do not infer failure from ret < 0 when
638 * arch code explicitly requested a successful Alpha return.
639 */
640 if (meta & ALPHA_SYSCALL_META_FORCE_SUCCESS) {
641 regs->r0 = ret;
642 regs->r19 = 0;
643 } else if (ret < 0) {
644 regs->r0 = -ret;
645 regs->r19 = 1;
646 } else {
647 regs->r0 = ret;
648 regs->r19 = 0;
649 }
650
651 instrumentation_end();
652 syscall_exit_to_user_mode(regs);
653}