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
43 static long
restore_sigcontext(struct sigcontext __user * sc,struct sigscratch * scr)44 restore_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
108 long
ia64_rt_sigreturn(struct sigscratch * scr)109 ia64_rt_sigreturn (struct sigscratch *scr)
110 {
111 extern char ia64_strace_leave_kernel, ia64_leave_kernel;
112 struct sigcontext __user *sc;
113 sigset_t set;
114 long retval;
115
116 sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc;
117
118 /*
119 * When we return to the previously executing context, r8 and r10 have already
120 * been setup the way we want them. Indeed, if the signal wasn't delivered while
121 * in a system call, we must not touch r8 or r10 as otherwise user-level state
122 * could be corrupted.
123 */
124 retval = (long) &ia64_leave_kernel;
125 if (test_thread_flag(TIF_SYSCALL_TRACE)
126 || test_thread_flag(TIF_SYSCALL_AUDIT))
127 /*
128 * strace expects to be notified after sigreturn returns even though the
129 * context to which we return may not be in the middle of a syscall.
130 * Thus, the return-value that strace displays for sigreturn is
131 * meaningless.
132 */
133 retval = (long) &ia64_strace_leave_kernel;
134
135 if (!access_ok(sc, sizeof(*sc)))
136 goto give_sigsegv;
137
138 if (GET_SIGSET(&set, &sc->sc_mask))
139 goto give_sigsegv;
140
141 set_current_blocked(&set);
142
143 if (restore_sigcontext(sc, scr))
144 goto give_sigsegv;
145
146 #if DEBUG_SIG
147 printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
148 current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip);
149 #endif
150 if (restore_altstack(&sc->sc_stack))
151 goto give_sigsegv;
152 return retval;
153
154 give_sigsegv:
155 force_sig(SIGSEGV);
156 return retval;
157 }
158
159 /*
160 * This does just the minimum required setup of sigcontext.
161 * Specifically, it only installs data that is either not knowable at
162 * the user-level or that gets modified before execution in the
163 * trampoline starts. Everything else is done at the user-level.
164 */
165 static long
setup_sigcontext(struct sigcontext __user * sc,sigset_t * mask,struct sigscratch * scr)166 setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr)
167 {
168 unsigned long flags = 0, ifs, cfm, nat;
169 long err = 0;
170
171 ifs = scr->pt.cr_ifs;
172
173 if (on_sig_stack((unsigned long) sc))
174 flags |= IA64_SC_FLAG_ONSTACK;
175 if ((ifs & (1UL << 63)) == 0)
176 /* if cr_ifs doesn't have the valid bit set, we got here through a syscall */
177 flags |= IA64_SC_FLAG_IN_SYSCALL;
178 cfm = ifs & ((1UL << 38) - 1);
179 ia64_flush_fph(current);
180 if ((current->thread.flags & IA64_THREAD_FPH_VALID)) {
181 flags |= IA64_SC_FLAG_FPH_VALID;
182 err = __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
183 }
184
185 nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat);
186
187 err |= __put_user(flags, &sc->sc_flags);
188 err |= __put_user(nat, &sc->sc_nat);
189 err |= PUT_SIGSET(mask, &sc->sc_mask);
190 err |= __put_user(cfm, &sc->sc_cfm);
191 err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um);
192 err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
193 err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat); /* ar.unat */
194 err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr); /* ar.fpsr */
195 err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
196 err |= __put_user(scr->pt.pr, &sc->sc_pr); /* predicates */
197 err |= __put_user(scr->pt.b0, &sc->sc_br[0]); /* b0 (rp) */
198 err |= __put_user(scr->pt.b6, &sc->sc_br[6]); /* b6 */
199 err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8); /* r1 */
200 err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8); /* r8-r11 */
201 err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8); /* r12-r13 */
202 err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8); /* r15 */
203 err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip);
204
205 if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
206 /* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */
207 err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv); /* ar.ccv */
208 err |= __put_user(scr->pt.b7, &sc->sc_br[7]); /* b7 */
209 err |= __put_user(scr->pt.r14, &sc->sc_gr[14]); /* r14 */
210 err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */
211 err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8); /* r2-r3 */
212 err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8); /* r16-r31 */
213 }
214 return err;
215 }
216
217 /*
218 * Check whether the register-backing store is already on the signal stack.
219 */
220 static inline int
rbs_on_sig_stack(unsigned long bsp)221 rbs_on_sig_stack (unsigned long bsp)
222 {
223 return (bsp - current->sas_ss_sp < current->sas_ss_size);
224 }
225
226 static long
setup_frame(struct ksignal * ksig,sigset_t * set,struct sigscratch * scr)227 setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
228 {
229 extern char __kernel_sigtramp[];
230 unsigned long tramp_addr, new_rbs = 0, new_sp;
231 struct sigframe __user *frame;
232 long err;
233
234 new_sp = scr->pt.r12;
235 tramp_addr = (unsigned long) __kernel_sigtramp;
236 if (ksig->ka.sa.sa_flags & SA_ONSTACK) {
237 int onstack = sas_ss_flags(new_sp);
238
239 if (onstack == 0) {
240 new_sp = current->sas_ss_sp + current->sas_ss_size;
241 /*
242 * We need to check for the register stack being on the
243 * signal stack separately, because it's switched
244 * separately (memory stack is switched in the kernel,
245 * register stack is switched in the signal trampoline).
246 */
247 if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
248 new_rbs = ALIGN(current->sas_ss_sp,
249 sizeof(long));
250 } else if (onstack == SS_ONSTACK) {
251 unsigned long check_sp;
252
253 /*
254 * If we are on the alternate signal stack and would
255 * overflow it, don't. Return an always-bogus address
256 * instead so we will die with SIGSEGV.
257 */
258 check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;
259 if (!likely(on_sig_stack(check_sp))) {
260 force_sigsegv(ksig->sig);
261 return 1;
262 }
263 }
264 }
265 frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
266
267 if (!access_ok(frame, sizeof(*frame))) {
268 force_sigsegv(ksig->sig);
269 return 1;
270 }
271
272 err = __put_user(ksig->sig, &frame->arg0);
273 err |= __put_user(&frame->info, &frame->arg1);
274 err |= __put_user(&frame->sc, &frame->arg2);
275 err |= __put_user(new_rbs, &frame->sc.sc_rbs_base);
276 err |= __put_user(0, &frame->sc.sc_loadrs); /* initialize to zero */
277 err |= __put_user(ksig->ka.sa.sa_handler, &frame->handler);
278
279 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
280
281 err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12);
282 err |= setup_sigcontext(&frame->sc, set, scr);
283
284 if (unlikely(err)) {
285 force_sigsegv(ksig->sig);
286 return 1;
287 }
288
289 scr->pt.r12 = (unsigned long) frame - 16; /* new stack pointer */
290 scr->pt.ar_fpsr = FPSR_DEFAULT; /* reset fpsr for signal handler */
291 scr->pt.cr_iip = tramp_addr;
292 ia64_psr(&scr->pt)->ri = 0; /* start executing in first slot */
293 ia64_psr(&scr->pt)->be = 0; /* force little-endian byte-order */
294 /*
295 * Force the interruption function mask to zero. This has no effect when a
296 * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is
297 * ignored), but it has the desirable effect of making it possible to deliver a
298 * signal with an incomplete register frame (which happens when a mandatory RSE
299 * load faults). Furthermore, it has no negative effect on the getting the user's
300 * dirty partition preserved, because that's governed by scr->pt.loadrs.
301 */
302 scr->pt.cr_ifs = (1UL << 63);
303
304 /*
305 * Note: this affects only the NaT bits of the scratch regs (the ones saved in
306 * pt_regs), which is exactly what we want.
307 */
308 scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */
309
310 #if DEBUG_SIG
311 printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n",
312 current->comm, current->pid, ksig->sig, scr->pt.r12, frame->sc.sc_ip, frame->handler);
313 #endif
314 return 0;
315 }
316
317 static long
handle_signal(struct ksignal * ksig,struct sigscratch * scr)318 handle_signal (struct ksignal *ksig, struct sigscratch *scr)
319 {
320 int ret = setup_frame(ksig, sigmask_to_save(), scr);
321
322 if (!ret)
323 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
324
325 return ret;
326 }
327
328 /*
329 * Note that `init' is a special process: it doesn't get signals it doesn't want to
330 * handle. Thus you cannot kill init even with a SIGKILL even by mistake.
331 */
332 void
ia64_do_signal(struct sigscratch * scr,long in_syscall)333 ia64_do_signal (struct sigscratch *scr, long in_syscall)
334 {
335 long restart = in_syscall;
336 long errno = scr->pt.r8;
337 struct ksignal ksig;
338
339 /*
340 * This only loops in the rare cases of handle_signal() failing, in which case we
341 * need to push through a forced SIGSEGV.
342 */
343 while (1) {
344 if (!get_signal(&ksig))
345 break;
346
347 /*
348 * get_signal() may have run a debugger (via notify_parent())
349 * and the debugger may have modified the state (e.g., to arrange for an
350 * inferior call), thus it's important to check for restarting _after_
351 * get_signal().
352 */
353 if ((long) scr->pt.r10 != -1)
354 /*
355 * A system calls has to be restarted only if one of the error codes
356 * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned. If r10
357 * isn't -1 then r8 doesn't hold an error code and we don't need to
358 * restart the syscall, so we can clear the "restart" flag here.
359 */
360 restart = 0;
361
362 if (ksig.sig <= 0)
363 break;
364
365 if (unlikely(restart)) {
366 switch (errno) {
367 case ERESTART_RESTARTBLOCK:
368 case ERESTARTNOHAND:
369 scr->pt.r8 = EINTR;
370 /* note: scr->pt.r10 is already -1 */
371 break;
372 case ERESTARTSYS:
373 if ((ksig.ka.sa.sa_flags & SA_RESTART) == 0) {
374 scr->pt.r8 = EINTR;
375 /* note: scr->pt.r10 is already -1 */
376 break;
377 }
378 fallthrough;
379 case ERESTARTNOINTR:
380 ia64_decrement_ip(&scr->pt);
381 restart = 0; /* don't restart twice if handle_signal() fails... */
382 }
383 }
384
385 /*
386 * Whee! Actually deliver the signal. If the delivery failed, we need to
387 * continue to iterate in this loop so we can deliver the SIGSEGV...
388 */
389 if (handle_signal(&ksig, scr))
390 return;
391 }
392
393 /* Did we come from a system call? */
394 if (restart) {
395 /* Restart the system call - no handlers present */
396 if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR
397 || errno == ERESTART_RESTARTBLOCK)
398 {
399 /*
400 * Note: the syscall number is in r15 which is saved in
401 * pt_regs so all we need to do here is adjust ip so that
402 * the "break" instruction gets re-executed.
403 */
404 ia64_decrement_ip(&scr->pt);
405 if (errno == ERESTART_RESTARTBLOCK)
406 scr->pt.r15 = __NR_restart_syscall;
407 }
408 }
409
410 /* if there's no signal to deliver, we just put the saved sigmask
411 * back */
412 restore_saved_sigmask();
413 }
414