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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Architecture-specific signal handling support.
4 *
5 * Copyright (C) 1999-2004 Hewlett-Packard Co
6 * David Mosberger-Tang <davidm@hpl.hp.com>
7 *
8 * Derived from i386 and Alpha versions.
9 */
10
11#include <linux/errno.h>
12#include <linux/kernel.h>
13#include <linux/mm.h>
14#include <linux/ptrace.h>
15#include <linux/tracehook.h>
16#include <linux/sched.h>
17#include <linux/signal.h>
18#include <linux/smp.h>
19#include <linux/stddef.h>
20#include <linux/tty.h>
21#include <linux/binfmts.h>
22#include <linux/unistd.h>
23#include <linux/wait.h>
24
25#include <asm/intrinsics.h>
26#include <linux/uaccess.h>
27#include <asm/rse.h>
28#include <asm/sigcontext.h>
29
30#include "sigframe.h"
31
32#define DEBUG_SIG 0
33#define STACK_ALIGN 16 /* minimal alignment for stack pointer */
34
35#if _NSIG_WORDS > 1
36# define PUT_SIGSET(k,u) __copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t))
37# define GET_SIGSET(k,u) __copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t))
38#else
39# define PUT_SIGSET(k,u) __put_user((k)->sig[0], &(u)->sig[0])
40# define GET_SIGSET(k,u) __get_user((k)->sig[0], &(u)->sig[0])
41#endif
42
43static long
44restore_sigcontext (struct sigcontext __user *sc, struct sigscratch *scr)
45{
46 unsigned long ip, flags, nat, um, cfm, rsc;
47 long err;
48
49 /* Always make any pending restarted system calls return -EINTR */
50 current->restart_block.fn = do_no_restart_syscall;
51
52 /* restore scratch that always needs gets updated during signal delivery: */
53 err = __get_user(flags, &sc->sc_flags);
54 err |= __get_user(nat, &sc->sc_nat);
55 err |= __get_user(ip, &sc->sc_ip); /* instruction pointer */
56 err |= __get_user(cfm, &sc->sc_cfm);
57 err |= __get_user(um, &sc->sc_um); /* user mask */
58 err |= __get_user(rsc, &sc->sc_ar_rsc);
59 err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat);
60 err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);
61 err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
62 err |= __get_user(scr->pt.pr, &sc->sc_pr); /* predicates */
63 err |= __get_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */
64 err |= __get_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */
65 err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 8); /* r1 */
66 err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8); /* r8-r11 */
67 err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 2*8); /* r12-r13 */
68 err |= __copy_from_user(&scr->pt.r15, &sc->sc_gr[15], 8); /* r15 */
69
70 scr->pt.cr_ifs = cfm | (1UL << 63);
71 scr->pt.ar_rsc = rsc | (3 << 2); /* force PL3 */
72
73 /* establish new instruction pointer: */
74 scr->pt.cr_iip = ip & ~0x3UL;
75 ia64_psr(&scr->pt)->ri = ip & 0x3;
76 scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM);
77
78 scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat);
79
80 if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
81 /* Restore most scratch-state only when not in syscall. */
82 err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */
83 err |= __get_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */
84 err |= __get_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */
85 err |= __copy_from_user(&scr->pt.ar_csd, &sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */
86 err |= __copy_from_user(&scr->pt.r2, &sc->sc_gr[2], 2*8); /* r2-r3 */
87 err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8); /* r16-r31 */
88 }
89
90 if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) {
91 struct ia64_psr *psr = ia64_psr(&scr->pt);
92
93 err |= __copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16);
94 psr->mfh = 0; /* drop signal handler's fph contents... */
95 preempt_disable();
96 if (psr->dfh)
97 ia64_drop_fpu(current);
98 else {
99 /* We already own the local fph, otherwise psr->dfh wouldn't be 0. */
100 __ia64_load_fpu(current->thread.fph);
101 ia64_set_local_fpu_owner(current);
102 }
103 preempt_enable();
104 }
105 return err;
106}
107
108long
109ia64_rt_sigreturn (struct sigscratch *scr)
110{
111 extern char ia64_strace_leave_kernel, ia64_leave_kernel;
112 struct sigcontext __user *sc;
113 struct siginfo si;
114 sigset_t set;
115 long retval;
116
117 sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc;
118
119 /*
120 * When we return to the previously executing context, r8 and r10 have already
121 * been setup the way we want them. Indeed, if the signal wasn't delivered while
122 * in a system call, we must not touch r8 or r10 as otherwise user-level state
123 * could be corrupted.
124 */
125 retval = (long) &ia64_leave_kernel;
126 if (test_thread_flag(TIF_SYSCALL_TRACE)
127 || test_thread_flag(TIF_SYSCALL_AUDIT))
128 /*
129 * strace expects to be notified after sigreturn returns even though the
130 * context to which we return may not be in the middle of a syscall.
131 * Thus, the return-value that strace displays for sigreturn is
132 * meaningless.
133 */
134 retval = (long) &ia64_strace_leave_kernel;
135
136 if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
137 goto give_sigsegv;
138
139 if (GET_SIGSET(&set, &sc->sc_mask))
140 goto give_sigsegv;
141
142 set_current_blocked(&set);
143
144 if (restore_sigcontext(sc, scr))
145 goto give_sigsegv;
146
147#if DEBUG_SIG
148 printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
149 current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip);
150#endif
151 if (restore_altstack(&sc->sc_stack))
152 goto give_sigsegv;
153 return retval;
154
155 give_sigsegv:
156 si.si_signo = SIGSEGV;
157 si.si_errno = 0;
158 si.si_code = SI_KERNEL;
159 si.si_pid = task_pid_vnr(current);
160 si.si_uid = from_kuid_munged(current_user_ns(), current_uid());
161 si.si_addr = sc;
162 force_sig_info(SIGSEGV, &si, current);
163 return retval;
164}
165
166/*
167 * This does just the minimum required setup of sigcontext.
168 * Specifically, it only installs data that is either not knowable at
169 * the user-level or that gets modified before execution in the
170 * trampoline starts. Everything else is done at the user-level.
171 */
172static long
173setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr)
174{
175 unsigned long flags = 0, ifs, cfm, nat;
176 long err = 0;
177
178 ifs = scr->pt.cr_ifs;
179
180 if (on_sig_stack((unsigned long) sc))
181 flags |= IA64_SC_FLAG_ONSTACK;
182 if ((ifs & (1UL << 63)) == 0)
183 /* if cr_ifs doesn't have the valid bit set, we got here through a syscall */
184 flags |= IA64_SC_FLAG_IN_SYSCALL;
185 cfm = ifs & ((1UL << 38) - 1);
186 ia64_flush_fph(current);
187 if ((current->thread.flags & IA64_THREAD_FPH_VALID)) {
188 flags |= IA64_SC_FLAG_FPH_VALID;
189 err = __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
190 }
191
192 nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat);
193
194 err |= __put_user(flags, &sc->sc_flags);
195 err |= __put_user(nat, &sc->sc_nat);
196 err |= PUT_SIGSET(mask, &sc->sc_mask);
197 err |= __put_user(cfm, &sc->sc_cfm);
198 err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um);
199 err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
200 err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat); /* ar.unat */
201 err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr); /* ar.fpsr */
202 err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
203 err |= __put_user(scr->pt.pr, &sc->sc_pr); /* predicates */
204 err |= __put_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */
205 err |= __put_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */
206 err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8); /* r1 */
207 err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8); /* r8-r11 */
208 err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8); /* r12-r13 */
209 err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8); /* r15 */
210 err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip);
211
212 if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
213 /* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */
214 err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */
215 err |= __put_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */
216 err |= __put_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */
217 err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */
218 err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8); /* r2-r3 */
219 err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8); /* r16-r31 */
220 }
221 return err;
222}
223
224/*
225 * Check whether the register-backing store is already on the signal stack.
226 */
227static inline int
228rbs_on_sig_stack (unsigned long bsp)
229{
230 return (bsp - current->sas_ss_sp < current->sas_ss_size);
231}
232
233static long
234force_sigsegv_info (int sig, void __user *addr)
235{
236 unsigned long flags;
237 struct siginfo si;
238
239 if (sig == SIGSEGV) {
240 /*
241 * Acquiring siglock around the sa_handler-update is almost
242 * certainly overkill, but this isn't a
243 * performance-critical path and I'd rather play it safe
244 * here than having to debug a nasty race if and when
245 * something changes in kernel/signal.c that would make it
246 * no longer safe to modify sa_handler without holding the
247 * lock.
248 */
249 spin_lock_irqsave(¤t->sighand->siglock, flags);
250 current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
251 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
252 }
253 si.si_signo = SIGSEGV;
254 si.si_errno = 0;
255 si.si_code = SI_KERNEL;
256 si.si_pid = task_pid_vnr(current);
257 si.si_uid = from_kuid_munged(current_user_ns(), current_uid());
258 si.si_addr = addr;
259 force_sig_info(SIGSEGV, &si, current);
260 return 1;
261}
262
263static long
264setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
265{
266 extern char __kernel_sigtramp[];
267 unsigned long tramp_addr, new_rbs = 0, new_sp;
268 struct sigframe __user *frame;
269 long err;
270
271 new_sp = scr->pt.r12;
272 tramp_addr = (unsigned long) __kernel_sigtramp;
273 if (ksig->ka.sa.sa_flags & SA_ONSTACK) {
274 int onstack = sas_ss_flags(new_sp);
275
276 if (onstack == 0) {
277 new_sp = current->sas_ss_sp + current->sas_ss_size;
278 /*
279 * We need to check for the register stack being on the
280 * signal stack separately, because it's switched
281 * separately (memory stack is switched in the kernel,
282 * register stack is switched in the signal trampoline).
283 */
284 if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
285 new_rbs = ALIGN(current->sas_ss_sp,
286 sizeof(long));
287 } else if (onstack == SS_ONSTACK) {
288 unsigned long check_sp;
289
290 /*
291 * If we are on the alternate signal stack and would
292 * overflow it, don't. Return an always-bogus address
293 * instead so we will die with SIGSEGV.
294 */
295 check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;
296 if (!likely(on_sig_stack(check_sp)))
297 return force_sigsegv_info(ksig->sig, (void __user *)
298 check_sp);
299 }
300 }
301 frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
302
303 if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
304 return force_sigsegv_info(ksig->sig, frame);
305
306 err = __put_user(ksig->sig, &frame->arg0);
307 err |= __put_user(&frame->info, &frame->arg1);
308 err |= __put_user(&frame->sc, &frame->arg2);
309 err |= __put_user(new_rbs, &frame->sc.sc_rbs_base);
310 err |= __put_user(0, &frame->sc.sc_loadrs); /* initialize to zero */
311 err |= __put_user(ksig->ka.sa.sa_handler, &frame->handler);
312
313 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
314
315 err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12);
316 err |= setup_sigcontext(&frame->sc, set, scr);
317
318 if (unlikely(err))
319 return force_sigsegv_info(ksig->sig, frame);
320
321 scr->pt.r12 = (unsigned long) frame - 16; /* new stack pointer */
322 scr->pt.ar_fpsr = FPSR_DEFAULT; /* reset fpsr for signal handler */
323 scr->pt.cr_iip = tramp_addr;
324 ia64_psr(&scr->pt)->ri = 0; /* start executing in first slot */
325 ia64_psr(&scr->pt)->be = 0; /* force little-endian byte-order */
326 /*
327 * Force the interruption function mask to zero. This has no effect when a
328 * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is
329 * ignored), but it has the desirable effect of making it possible to deliver a
330 * signal with an incomplete register frame (which happens when a mandatory RSE
331 * load faults). Furthermore, it has no negative effect on the getting the user's
332 * dirty partition preserved, because that's governed by scr->pt.loadrs.
333 */
334 scr->pt.cr_ifs = (1UL << 63);
335
336 /*
337 * Note: this affects only the NaT bits of the scratch regs (the ones saved in
338 * pt_regs), which is exactly what we want.
339 */
340 scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */
341
342#if DEBUG_SIG
343 printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n",
344 current->comm, current->pid, ksig->sig, scr->pt.r12, frame->sc.sc_ip, frame->handler);
345#endif
346 return 0;
347}
348
349static long
350handle_signal (struct ksignal *ksig, struct sigscratch *scr)
351{
352 int ret = setup_frame(ksig, sigmask_to_save(), scr);
353
354 if (!ret)
355 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
356
357 return ret;
358}
359
360/*
361 * Note that `init' is a special process: it doesn't get signals it doesn't want to
362 * handle. Thus you cannot kill init even with a SIGKILL even by mistake.
363 */
364void
365ia64_do_signal (struct sigscratch *scr, long in_syscall)
366{
367 long restart = in_syscall;
368 long errno = scr->pt.r8;
369 struct ksignal ksig;
370
371 /*
372 * This only loops in the rare cases of handle_signal() failing, in which case we
373 * need to push through a forced SIGSEGV.
374 */
375 while (1) {
376 get_signal(&ksig);
377
378 /*
379 * get_signal_to_deliver() may have run a debugger (via notify_parent())
380 * and the debugger may have modified the state (e.g., to arrange for an
381 * inferior call), thus it's important to check for restarting _after_
382 * get_signal_to_deliver().
383 */
384 if ((long) scr->pt.r10 != -1)
385 /*
386 * A system calls has to be restarted only if one of the error codes
387 * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned. If r10
388 * isn't -1 then r8 doesn't hold an error code and we don't need to
389 * restart the syscall, so we can clear the "restart" flag here.
390 */
391 restart = 0;
392
393 if (ksig.sig <= 0)
394 break;
395
396 if (unlikely(restart)) {
397 switch (errno) {
398 case ERESTART_RESTARTBLOCK:
399 case ERESTARTNOHAND:
400 scr->pt.r8 = EINTR;
401 /* note: scr->pt.r10 is already -1 */
402 break;
403
404 case ERESTARTSYS:
405 if ((ksig.ka.sa.sa_flags & SA_RESTART) == 0) {
406 scr->pt.r8 = EINTR;
407 /* note: scr->pt.r10 is already -1 */
408 break;
409 }
410 case ERESTARTNOINTR:
411 ia64_decrement_ip(&scr->pt);
412 restart = 0; /* don't restart twice if handle_signal() fails... */
413 }
414 }
415
416 /*
417 * Whee! Actually deliver the signal. If the delivery failed, we need to
418 * continue to iterate in this loop so we can deliver the SIGSEGV...
419 */
420 if (handle_signal(&ksig, scr))
421 return;
422 }
423
424 /* Did we come from a system call? */
425 if (restart) {
426 /* Restart the system call - no handlers present */
427 if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR
428 || errno == ERESTART_RESTARTBLOCK)
429 {
430 /*
431 * Note: the syscall number is in r15 which is saved in
432 * pt_regs so all we need to do here is adjust ip so that
433 * the "break" instruction gets re-executed.
434 */
435 ia64_decrement_ip(&scr->pt);
436 if (errno == ERESTART_RESTARTBLOCK)
437 scr->pt.r15 = __NR_restart_syscall;
438 }
439 }
440
441 /* if there's no signal to deliver, we just put the saved sigmask
442 * back */
443 restore_saved_sigmask();
444}