Loading...
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/arch/parisc/kernel/signal.c: Architecture-specific signal
4 * handling support.
5 *
6 * Copyright (C) 2000 David Huggins-Daines <dhd@debian.org>
7 * Copyright (C) 2000 Linuxcare, Inc.
8 *
9 * Based on the ia64, i386, and alpha versions.
10 *
11 * Like the IA-64, we are a recent enough port (we are *starting*
12 * with glibc2.2) that we do not need to support the old non-realtime
13 * Linux signals. Therefore we don't.
14 */
15
16#include <linux/sched.h>
17#include <linux/sched/debug.h>
18#include <linux/mm.h>
19#include <linux/smp.h>
20#include <linux/kernel.h>
21#include <linux/signal.h>
22#include <linux/errno.h>
23#include <linux/wait.h>
24#include <linux/ptrace.h>
25#include <linux/tracehook.h>
26#include <linux/unistd.h>
27#include <linux/stddef.h>
28#include <linux/compat.h>
29#include <linux/elf.h>
30#include <asm/ucontext.h>
31#include <asm/rt_sigframe.h>
32#include <linux/uaccess.h>
33#include <asm/pgalloc.h>
34#include <asm/cacheflush.h>
35#include <asm/asm-offsets.h>
36
37#ifdef CONFIG_COMPAT
38#include "signal32.h"
39#endif
40
41#define DEBUG_SIG 0
42#define DEBUG_SIG_LEVEL 2
43
44#if DEBUG_SIG
45#define DBG(LEVEL, ...) \
46 ((DEBUG_SIG_LEVEL >= LEVEL) \
47 ? printk(__VA_ARGS__) : (void) 0)
48#else
49#define DBG(LEVEL, ...)
50#endif
51
52/* gcc will complain if a pointer is cast to an integer of different
53 * size. If you really need to do this (and we do for an ELF32 user
54 * application in an ELF64 kernel) then you have to do a cast to an
55 * integer of the same size first. The A() macro accomplishes
56 * this. */
57#define A(__x) ((unsigned long)(__x))
58
59/*
60 * Do a signal return - restore sigcontext.
61 */
62
63/* Trampoline for calling rt_sigreturn() */
64#define INSN_LDI_R25_0 0x34190000 /* ldi 0,%r25 (in_syscall=0) */
65#define INSN_LDI_R25_1 0x34190002 /* ldi 1,%r25 (in_syscall=1) */
66#define INSN_LDI_R20 0x3414015a /* ldi __NR_rt_sigreturn,%r20 */
67#define INSN_BLE_SR2_R0 0xe4008200 /* be,l 0x100(%sr2,%r0),%sr0,%r31 */
68/* For debugging */
69#define INSN_DIE_HORRIBLY 0x68000ccc /* stw %r0,0x666(%sr0,%r0) */
70
71static long
72restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
73{
74 long err = 0;
75
76 err |= __copy_from_user(regs->gr, sc->sc_gr, sizeof(regs->gr));
77 err |= __copy_from_user(regs->fr, sc->sc_fr, sizeof(regs->fr));
78 err |= __copy_from_user(regs->iaoq, sc->sc_iaoq, sizeof(regs->iaoq));
79 err |= __copy_from_user(regs->iasq, sc->sc_iasq, sizeof(regs->iasq));
80 err |= __get_user(regs->sar, &sc->sc_sar);
81 DBG(2,"restore_sigcontext: iaoq is %#lx / %#lx\n",
82 regs->iaoq[0],regs->iaoq[1]);
83 DBG(2,"restore_sigcontext: r28 is %ld\n", regs->gr[28]);
84 return err;
85}
86
87void
88sys_rt_sigreturn(struct pt_regs *regs, int in_syscall)
89{
90 struct rt_sigframe __user *frame;
91 sigset_t set;
92 unsigned long usp = (regs->gr[30] & ~(0x01UL));
93 unsigned long sigframe_size = PARISC_RT_SIGFRAME_SIZE;
94#ifdef CONFIG_64BIT
95 struct compat_rt_sigframe __user * compat_frame;
96
97 if (is_compat_task())
98 sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
99#endif
100
101 current->restart_block.fn = do_no_restart_syscall;
102
103 /* Unwind the user stack to get the rt_sigframe structure. */
104 frame = (struct rt_sigframe __user *)
105 (usp - sigframe_size);
106 DBG(2,"sys_rt_sigreturn: frame is %p\n", frame);
107
108 regs->orig_r28 = 1; /* no restarts for sigreturn */
109
110#ifdef CONFIG_64BIT
111 compat_frame = (struct compat_rt_sigframe __user *)frame;
112
113 if (is_compat_task()) {
114 DBG(2,"sys_rt_sigreturn: ELF32 process.\n");
115 if (get_compat_sigset(&set, &compat_frame->uc.uc_sigmask))
116 goto give_sigsegv;
117 } else
118#endif
119 {
120 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
121 goto give_sigsegv;
122 }
123
124 set_current_blocked(&set);
125
126 /* Good thing we saved the old gr[30], eh? */
127#ifdef CONFIG_64BIT
128 if (is_compat_task()) {
129 DBG(1,"sys_rt_sigreturn: compat_frame->uc.uc_mcontext 0x%p\n",
130 &compat_frame->uc.uc_mcontext);
131// FIXME: Load upper half from register file
132 if (restore_sigcontext32(&compat_frame->uc.uc_mcontext,
133 &compat_frame->regs, regs))
134 goto give_sigsegv;
135 DBG(1,"sys_rt_sigreturn: usp %#08lx stack 0x%p\n",
136 usp, &compat_frame->uc.uc_stack);
137 if (compat_restore_altstack(&compat_frame->uc.uc_stack))
138 goto give_sigsegv;
139 } else
140#endif
141 {
142 DBG(1,"sys_rt_sigreturn: frame->uc.uc_mcontext 0x%p\n",
143 &frame->uc.uc_mcontext);
144 if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
145 goto give_sigsegv;
146 DBG(1,"sys_rt_sigreturn: usp %#08lx stack 0x%p\n",
147 usp, &frame->uc.uc_stack);
148 if (restore_altstack(&frame->uc.uc_stack))
149 goto give_sigsegv;
150 }
151
152
153
154 /* If we are on the syscall path IAOQ will not be restored, and
155 * if we are on the interrupt path we must not corrupt gr31.
156 */
157 if (in_syscall)
158 regs->gr[31] = regs->iaoq[0];
159#if DEBUG_SIG
160 DBG(1,"sys_rt_sigreturn: returning to %#lx, DUMPING REGS:\n", regs->iaoq[0]);
161 show_regs(regs);
162#endif
163 return;
164
165give_sigsegv:
166 DBG(1,"sys_rt_sigreturn: Sending SIGSEGV\n");
167 force_sig(SIGSEGV);
168 return;
169}
170
171/*
172 * Set up a signal frame.
173 */
174
175static inline void __user *
176get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
177{
178 /*FIXME: ELF32 vs. ELF64 has different frame_size, but since we
179 don't use the parameter it doesn't matter */
180
181 DBG(1,"get_sigframe: ka = %#lx, sp = %#lx, frame_size = %#lx\n",
182 (unsigned long)ka, sp, frame_size);
183
184 /* Align alternate stack and reserve 64 bytes for the signal
185 handler's frame marker. */
186 if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
187 sp = (current->sas_ss_sp + 0x7f) & ~0x3f; /* Stacks grow up! */
188
189 DBG(1,"get_sigframe: Returning sp = %#lx\n", (unsigned long)sp);
190 return (void __user *) sp; /* Stacks grow up. Fun. */
191}
192
193static long
194setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, int in_syscall)
195
196{
197 unsigned long flags = 0;
198 long err = 0;
199
200 if (on_sig_stack((unsigned long) sc))
201 flags |= PARISC_SC_FLAG_ONSTACK;
202 if (in_syscall) {
203 flags |= PARISC_SC_FLAG_IN_SYSCALL;
204 /* regs->iaoq is undefined in the syscall return path */
205 err |= __put_user(regs->gr[31], &sc->sc_iaoq[0]);
206 err |= __put_user(regs->gr[31]+4, &sc->sc_iaoq[1]);
207 err |= __put_user(regs->sr[3], &sc->sc_iasq[0]);
208 err |= __put_user(regs->sr[3], &sc->sc_iasq[1]);
209 DBG(1,"setup_sigcontext: iaoq %#lx / %#lx (in syscall)\n",
210 regs->gr[31], regs->gr[31]+4);
211 } else {
212 err |= __copy_to_user(sc->sc_iaoq, regs->iaoq, sizeof(regs->iaoq));
213 err |= __copy_to_user(sc->sc_iasq, regs->iasq, sizeof(regs->iasq));
214 DBG(1,"setup_sigcontext: iaoq %#lx / %#lx (not in syscall)\n",
215 regs->iaoq[0], regs->iaoq[1]);
216 }
217
218 err |= __put_user(flags, &sc->sc_flags);
219 err |= __copy_to_user(sc->sc_gr, regs->gr, sizeof(regs->gr));
220 err |= __copy_to_user(sc->sc_fr, regs->fr, sizeof(regs->fr));
221 err |= __put_user(regs->sar, &sc->sc_sar);
222 DBG(1,"setup_sigcontext: r28 is %ld\n", regs->gr[28]);
223
224 return err;
225}
226
227static long
228setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs,
229 int in_syscall)
230{
231 struct rt_sigframe __user *frame;
232 unsigned long rp, usp;
233 unsigned long haddr, sigframe_size;
234 unsigned long start, end;
235 int err = 0;
236#ifdef CONFIG_64BIT
237 struct compat_rt_sigframe __user * compat_frame;
238#endif
239
240 usp = (regs->gr[30] & ~(0x01UL));
241 /*FIXME: frame_size parameter is unused, remove it. */
242 frame = get_sigframe(&ksig->ka, usp, sizeof(*frame));
243
244 DBG(1,"SETUP_RT_FRAME: START\n");
245 DBG(1,"setup_rt_frame: frame %p info %p\n", frame, ksig->info);
246
247
248#ifdef CONFIG_64BIT
249
250 compat_frame = (struct compat_rt_sigframe __user *)frame;
251
252 if (is_compat_task()) {
253 DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &compat_frame->info);
254 err |= copy_siginfo_to_user32(&compat_frame->info, &ksig->info);
255 err |= __compat_save_altstack( &compat_frame->uc.uc_stack, regs->gr[30]);
256 DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &compat_frame->uc);
257 DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &compat_frame->uc.uc_mcontext);
258 err |= setup_sigcontext32(&compat_frame->uc.uc_mcontext,
259 &compat_frame->regs, regs, in_syscall);
260 err |= put_compat_sigset(&compat_frame->uc.uc_sigmask, set,
261 sizeof(compat_sigset_t));
262 } else
263#endif
264 {
265 DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &frame->info);
266 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
267 err |= __save_altstack(&frame->uc.uc_stack, regs->gr[30]);
268 DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &frame->uc);
269 DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &frame->uc.uc_mcontext);
270 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, in_syscall);
271 /* FIXME: Should probably be converted as well for the compat case */
272 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
273 }
274
275 if (err)
276 return -EFAULT;
277
278 /* Set up to return from userspace. If provided, use a stub
279 already in userspace. The first words of tramp are used to
280 save the previous sigrestartblock trampoline that might be
281 on the stack. We start the sigreturn trampoline at
282 SIGRESTARTBLOCK_TRAMP+X. */
283 err |= __put_user(in_syscall ? INSN_LDI_R25_1 : INSN_LDI_R25_0,
284 &frame->tramp[SIGRESTARTBLOCK_TRAMP+0]);
285 err |= __put_user(INSN_LDI_R20,
286 &frame->tramp[SIGRESTARTBLOCK_TRAMP+1]);
287 err |= __put_user(INSN_BLE_SR2_R0,
288 &frame->tramp[SIGRESTARTBLOCK_TRAMP+2]);
289 err |= __put_user(INSN_NOP, &frame->tramp[SIGRESTARTBLOCK_TRAMP+3]);
290
291#if DEBUG_SIG
292 /* Assert that we're flushing in the correct space... */
293 {
294 unsigned long sid;
295 asm ("mfsp %%sr3,%0" : "=r" (sid));
296 DBG(1,"setup_rt_frame: Flushing 64 bytes at space %#x offset %p\n",
297 sid, frame->tramp);
298 }
299#endif
300
301 start = (unsigned long) &frame->tramp[0];
302 end = (unsigned long) &frame->tramp[TRAMP_SIZE];
303 flush_user_dcache_range_asm(start, end);
304 flush_user_icache_range_asm(start, end);
305
306 /* TRAMP Words 0-4, Length 5 = SIGRESTARTBLOCK_TRAMP
307 * TRAMP Words 5-9, Length 4 = SIGRETURN_TRAMP
308 * So the SIGRETURN_TRAMP is at the end of SIGRESTARTBLOCK_TRAMP
309 */
310 rp = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP];
311
312 if (err)
313 return -EFAULT;
314
315 haddr = A(ksig->ka.sa.sa_handler);
316 /* The sa_handler may be a pointer to a function descriptor */
317#ifdef CONFIG_64BIT
318 if (is_compat_task()) {
319#endif
320 if (haddr & PA_PLABEL_FDESC) {
321 Elf32_Fdesc fdesc;
322 Elf32_Fdesc __user *ufdesc = (Elf32_Fdesc __user *)A(haddr & ~3);
323
324 err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
325
326 if (err)
327 return -EFAULT;
328
329 haddr = fdesc.addr;
330 regs->gr[19] = fdesc.gp;
331 }
332#ifdef CONFIG_64BIT
333 } else {
334 Elf64_Fdesc fdesc;
335 Elf64_Fdesc __user *ufdesc = (Elf64_Fdesc __user *)A(haddr & ~3);
336
337 err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
338
339 if (err)
340 return -EFAULT;
341
342 haddr = fdesc.addr;
343 regs->gr[19] = fdesc.gp;
344 DBG(1,"setup_rt_frame: 64 bit signal, exe=%#lx, r19=%#lx, in_syscall=%d\n",
345 haddr, regs->gr[19], in_syscall);
346 }
347#endif
348
349 /* The syscall return path will create IAOQ values from r31.
350 */
351 sigframe_size = PARISC_RT_SIGFRAME_SIZE;
352#ifdef CONFIG_64BIT
353 if (is_compat_task())
354 sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
355#endif
356 if (in_syscall) {
357 regs->gr[31] = haddr;
358#ifdef CONFIG_64BIT
359 if (!test_thread_flag(TIF_32BIT))
360 sigframe_size |= 1;
361#endif
362 } else {
363 unsigned long psw = USER_PSW;
364#ifdef CONFIG_64BIT
365 if (!test_thread_flag(TIF_32BIT))
366 psw |= PSW_W;
367#endif
368
369 /* If we are singlestepping, arrange a trap to be delivered
370 when we return to userspace. Note the semantics -- we
371 should trap before the first insn in the handler is
372 executed. Ref:
373 http://sources.redhat.com/ml/gdb/2004-11/msg00245.html
374 */
375 if (pa_psw(current)->r) {
376 pa_psw(current)->r = 0;
377 psw |= PSW_R;
378 mtctl(-1, 0);
379 }
380
381 regs->gr[0] = psw;
382 regs->iaoq[0] = haddr | 3;
383 regs->iaoq[1] = regs->iaoq[0] + 4;
384 }
385
386 regs->gr[2] = rp; /* userland return pointer */
387 regs->gr[26] = ksig->sig; /* signal number */
388
389#ifdef CONFIG_64BIT
390 if (is_compat_task()) {
391 regs->gr[25] = A(&compat_frame->info); /* siginfo pointer */
392 regs->gr[24] = A(&compat_frame->uc); /* ucontext pointer */
393 } else
394#endif
395 {
396 regs->gr[25] = A(&frame->info); /* siginfo pointer */
397 regs->gr[24] = A(&frame->uc); /* ucontext pointer */
398 }
399
400 DBG(1,"setup_rt_frame: making sigreturn frame: %#lx + %#lx = %#lx\n",
401 regs->gr[30], sigframe_size,
402 regs->gr[30] + sigframe_size);
403 /* Raise the user stack pointer to make a proper call frame. */
404 regs->gr[30] = (A(frame) + sigframe_size);
405
406
407 DBG(1,"setup_rt_frame: sig deliver (%s,%d) frame=0x%p sp=%#lx iaoq=%#lx/%#lx rp=%#lx\n",
408 current->comm, current->pid, frame, regs->gr[30],
409 regs->iaoq[0], regs->iaoq[1], rp);
410
411 return 0;
412}
413
414/*
415 * OK, we're invoking a handler.
416 */
417
418static void
419handle_signal(struct ksignal *ksig, struct pt_regs *regs, int in_syscall)
420{
421 int ret;
422 sigset_t *oldset = sigmask_to_save();
423
424 DBG(1,"handle_signal: sig=%ld, ka=%p, info=%p, oldset=%p, regs=%p\n",
425 ksig->sig, ksig->ka, ksig->info, oldset, regs);
426
427 /* Set up the stack frame */
428 ret = setup_rt_frame(ksig, oldset, regs, in_syscall);
429
430 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP) ||
431 test_thread_flag(TIF_BLOCKSTEP));
432
433 DBG(1,KERN_DEBUG "do_signal: Exit (success), regs->gr[28] = %ld\n",
434 regs->gr[28]);
435}
436
437/*
438 * Check how the syscall number gets loaded into %r20 within
439 * the delay branch in userspace and adjust as needed.
440 */
441
442static void check_syscallno_in_delay_branch(struct pt_regs *regs)
443{
444 u32 opcode, source_reg;
445 u32 __user *uaddr;
446 int err;
447
448 /* Usually we don't have to restore %r20 (the system call number)
449 * because it gets loaded in the delay slot of the branch external
450 * instruction via the ldi instruction.
451 * In some cases a register-to-register copy instruction might have
452 * been used instead, in which case we need to copy the syscall
453 * number into the source register before returning to userspace.
454 */
455
456 /* A syscall is just a branch, so all we have to do is fiddle the
457 * return pointer so that the ble instruction gets executed again.
458 */
459 regs->gr[31] -= 8; /* delayed branching */
460
461 /* Get assembler opcode of code in delay branch */
462 uaddr = (unsigned int *) ((regs->gr[31] & ~3) + 4);
463 err = get_user(opcode, uaddr);
464 if (err)
465 return;
466
467 /* Check if delay branch uses "ldi int,%r20" */
468 if ((opcode & 0xffff0000) == 0x34140000)
469 return; /* everything ok, just return */
470
471 /* Check if delay branch uses "nop" */
472 if (opcode == INSN_NOP)
473 return;
474
475 /* Check if delay branch uses "copy %rX,%r20" */
476 if ((opcode & 0xffe0ffff) == 0x08000254) {
477 source_reg = (opcode >> 16) & 31;
478 regs->gr[source_reg] = regs->gr[20];
479 return;
480 }
481
482 pr_warn("syscall restart: %s (pid %d): unexpected opcode 0x%08x\n",
483 current->comm, task_pid_nr(current), opcode);
484}
485
486static inline void
487syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
488{
489 if (regs->orig_r28)
490 return;
491 regs->orig_r28 = 1; /* no more restarts */
492 /* Check the return code */
493 switch (regs->gr[28]) {
494 case -ERESTART_RESTARTBLOCK:
495 case -ERESTARTNOHAND:
496 DBG(1,"ERESTARTNOHAND: returning -EINTR\n");
497 regs->gr[28] = -EINTR;
498 break;
499
500 case -ERESTARTSYS:
501 if (!(ka->sa.sa_flags & SA_RESTART)) {
502 DBG(1,"ERESTARTSYS: putting -EINTR\n");
503 regs->gr[28] = -EINTR;
504 break;
505 }
506 /* fallthrough */
507 case -ERESTARTNOINTR:
508 check_syscallno_in_delay_branch(regs);
509 break;
510 }
511}
512
513static inline void
514insert_restart_trampoline(struct pt_regs *regs)
515{
516 if (regs->orig_r28)
517 return;
518 regs->orig_r28 = 1; /* no more restarts */
519 switch(regs->gr[28]) {
520 case -ERESTART_RESTARTBLOCK: {
521 /* Restart the system call - no handlers present */
522 unsigned int *usp = (unsigned int *)regs->gr[30];
523 unsigned long start = (unsigned long) &usp[2];
524 unsigned long end = (unsigned long) &usp[5];
525 long err = 0;
526
527 /* Setup a trampoline to restart the syscall
528 * with __NR_restart_syscall
529 *
530 * 0: <return address (orig r31)>
531 * 4: <2nd half for 64-bit>
532 * 8: ldw 0(%sp), %r31
533 * 12: be 0x100(%sr2, %r0)
534 * 16: ldi __NR_restart_syscall, %r20
535 */
536#ifdef CONFIG_64BIT
537 err |= put_user(regs->gr[31] >> 32, &usp[0]);
538 err |= put_user(regs->gr[31] & 0xffffffff, &usp[1]);
539 err |= put_user(0x0fc010df, &usp[2]);
540#else
541 err |= put_user(regs->gr[31], &usp[0]);
542 err |= put_user(0x0fc0109f, &usp[2]);
543#endif
544 err |= put_user(0xe0008200, &usp[3]);
545 err |= put_user(0x34140000, &usp[4]);
546
547 WARN_ON(err);
548
549 /* flush data/instruction cache for new insns */
550 flush_user_dcache_range_asm(start, end);
551 flush_user_icache_range_asm(start, end);
552
553 regs->gr[31] = regs->gr[30] + 8;
554 return;
555 }
556 case -ERESTARTNOHAND:
557 case -ERESTARTSYS:
558 case -ERESTARTNOINTR:
559 check_syscallno_in_delay_branch(regs);
560 return;
561 default:
562 break;
563 }
564}
565
566/*
567 * Note that 'init' is a special process: it doesn't get signals it doesn't
568 * want to handle. Thus you cannot kill init even with a SIGKILL even by
569 * mistake.
570 *
571 * We need to be able to restore the syscall arguments (r21-r26) to
572 * restart syscalls. Thus, the syscall path should save them in the
573 * pt_regs structure (it's okay to do so since they are caller-save
574 * registers). As noted below, the syscall number gets restored for
575 * us due to the magic of delayed branching.
576 */
577asmlinkage void
578do_signal(struct pt_regs *regs, long in_syscall)
579{
580 struct ksignal ksig;
581
582 DBG(1,"\ndo_signal: regs=0x%p, sr7 %#lx, in_syscall=%d\n",
583 regs, regs->sr[7], in_syscall);
584
585 if (get_signal(&ksig)) {
586 DBG(3,"do_signal: signr = %d, regs->gr[28] = %ld\n", signr, regs->gr[28]);
587 /* Restart a system call if necessary. */
588 if (in_syscall)
589 syscall_restart(regs, &ksig.ka);
590
591 handle_signal(&ksig, regs, in_syscall);
592 return;
593 }
594
595 /* Did we come from a system call? */
596 if (in_syscall)
597 insert_restart_trampoline(regs);
598
599 DBG(1,"do_signal: Exit (not delivered), regs->gr[28] = %ld\n",
600 regs->gr[28]);
601
602 restore_saved_sigmask();
603}
604
605void do_notify_resume(struct pt_regs *regs, long in_syscall)
606{
607 if (test_thread_flag(TIF_SIGPENDING))
608 do_signal(regs, in_syscall);
609
610 if (test_thread_flag(TIF_NOTIFY_RESUME)) {
611 clear_thread_flag(TIF_NOTIFY_RESUME);
612 tracehook_notify_resume(regs);
613 }
614}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * PA-RISC architecture-specific signal handling support.
4 *
5 * Copyright (C) 2000 David Huggins-Daines <dhd@debian.org>
6 * Copyright (C) 2000 Linuxcare, Inc.
7 * Copyright (C) 2000-2022 Helge Deller <deller@gmx.de>
8 * Copyright (C) 2022 John David Anglin <dave.anglin@bell.net>
9 *
10 * Based on the ia64, i386, and alpha versions.
11 */
12
13#include <linux/sched.h>
14#include <linux/sched/debug.h>
15#include <linux/mm.h>
16#include <linux/smp.h>
17#include <linux/kernel.h>
18#include <linux/signal.h>
19#include <linux/errno.h>
20#include <linux/wait.h>
21#include <linux/ptrace.h>
22#include <linux/resume_user_mode.h>
23#include <linux/unistd.h>
24#include <linux/stddef.h>
25#include <linux/compat.h>
26#include <linux/elf.h>
27#include <asm/ucontext.h>
28#include <asm/rt_sigframe.h>
29#include <linux/uaccess.h>
30#include <asm/cacheflush.h>
31#include <asm/asm-offsets.h>
32#include <asm/vdso.h>
33
34#ifdef CONFIG_COMPAT
35#include "signal32.h"
36#endif
37
38#define DEBUG_SIG 0
39#define DEBUG_SIG_LEVEL 2
40
41#if DEBUG_SIG
42#define DBG(LEVEL, ...) \
43 ((DEBUG_SIG_LEVEL >= LEVEL) \
44 ? printk(__VA_ARGS__) : (void) 0)
45#else
46#define DBG(LEVEL, ...)
47#endif
48
49/* gcc will complain if a pointer is cast to an integer of different
50 * size. If you really need to do this (and we do for an ELF32 user
51 * application in an ELF64 kernel) then you have to do a cast to an
52 * integer of the same size first. The A() macro accomplishes
53 * this. */
54#define A(__x) ((unsigned long)(__x))
55
56/*
57 * Do a signal return - restore sigcontext.
58 */
59
60static long
61restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
62{
63 long err = 0;
64
65 err |= __copy_from_user(regs->gr, sc->sc_gr, sizeof(regs->gr));
66 err |= __copy_from_user(regs->fr, sc->sc_fr, sizeof(regs->fr));
67 err |= __copy_from_user(regs->iaoq, sc->sc_iaoq, sizeof(regs->iaoq));
68 err |= __copy_from_user(regs->iasq, sc->sc_iasq, sizeof(regs->iasq));
69 err |= __get_user(regs->sar, &sc->sc_sar);
70 DBG(2, "%s: iaoq is %#lx / %#lx\n",
71 __func__, regs->iaoq[0], regs->iaoq[1]);
72 DBG(2, "%s: r28 is %ld\n", __func__, regs->gr[28]);
73 return err;
74}
75
76asmlinkage void
77sys_rt_sigreturn(struct pt_regs *regs, int in_syscall)
78{
79 struct rt_sigframe __user *frame;
80 sigset_t set;
81 unsigned long usp = (regs->gr[30] & ~(0x01UL));
82 unsigned long sigframe_size = PARISC_RT_SIGFRAME_SIZE;
83#ifdef CONFIG_64BIT
84 struct compat_rt_sigframe __user * compat_frame;
85
86 if (is_compat_task())
87 sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
88#endif
89
90 current->restart_block.fn = do_no_restart_syscall;
91
92 /* Unwind the user stack to get the rt_sigframe structure. */
93 frame = (struct rt_sigframe __user *)
94 (usp - sigframe_size);
95 DBG(2, "%s: frame is %p pid %d\n", __func__, frame, task_pid_nr(current));
96
97 regs->orig_r28 = 1; /* no restarts for sigreturn */
98
99#ifdef CONFIG_64BIT
100 compat_frame = (struct compat_rt_sigframe __user *)frame;
101
102 if (is_compat_task()) {
103 if (get_compat_sigset(&set, &compat_frame->uc.uc_sigmask))
104 goto give_sigsegv;
105 } else
106#endif
107 {
108 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
109 goto give_sigsegv;
110 }
111
112 set_current_blocked(&set);
113
114 /* Good thing we saved the old gr[30], eh? */
115#ifdef CONFIG_64BIT
116 if (is_compat_task()) {
117 DBG(1, "%s: compat_frame->uc.uc_mcontext 0x%p\n",
118 __func__, &compat_frame->uc.uc_mcontext);
119// FIXME: Load upper half from register file
120 if (restore_sigcontext32(&compat_frame->uc.uc_mcontext,
121 &compat_frame->regs, regs))
122 goto give_sigsegv;
123 DBG(1, "%s: usp %#08lx stack 0x%p\n",
124 __func__, usp, &compat_frame->uc.uc_stack);
125 if (compat_restore_altstack(&compat_frame->uc.uc_stack))
126 goto give_sigsegv;
127 } else
128#endif
129 {
130 DBG(1, "%s: frame->uc.uc_mcontext 0x%p\n",
131 __func__, &frame->uc.uc_mcontext);
132 if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
133 goto give_sigsegv;
134 DBG(1, "%s: usp %#08lx stack 0x%p\n",
135 __func__, usp, &frame->uc.uc_stack);
136 if (restore_altstack(&frame->uc.uc_stack))
137 goto give_sigsegv;
138 }
139
140
141
142 /* If we are on the syscall path IAOQ will not be restored, and
143 * if we are on the interrupt path we must not corrupt gr31.
144 */
145 if (in_syscall)
146 regs->gr[31] = regs->iaoq[0];
147
148 return;
149
150give_sigsegv:
151 DBG(1, "%s: Sending SIGSEGV\n", __func__);
152 force_sig(SIGSEGV);
153 return;
154}
155
156/*
157 * Set up a signal frame.
158 */
159
160static inline void __user *
161get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
162{
163 /*FIXME: ELF32 vs. ELF64 has different frame_size, but since we
164 don't use the parameter it doesn't matter */
165
166 DBG(1, "%s: ka = %#lx, sp = %#lx, frame_size = %zu\n",
167 __func__, (unsigned long)ka, sp, frame_size);
168
169 /* Align alternate stack and reserve 64 bytes for the signal
170 handler's frame marker. */
171 if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
172 sp = (current->sas_ss_sp + 0x7f) & ~0x3f; /* Stacks grow up! */
173
174 DBG(1, "%s: Returning sp = %#lx\n", __func__, (unsigned long)sp);
175 return (void __user *) sp; /* Stacks grow up. Fun. */
176}
177
178static long
179setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, long in_syscall)
180
181{
182 unsigned long flags = 0;
183 long err = 0;
184
185 if (on_sig_stack((unsigned long) sc))
186 flags |= PARISC_SC_FLAG_ONSTACK;
187 if (in_syscall) {
188 flags |= PARISC_SC_FLAG_IN_SYSCALL;
189 /* regs->iaoq is undefined in the syscall return path */
190 err |= __put_user(regs->gr[31], &sc->sc_iaoq[0]);
191 err |= __put_user(regs->gr[31]+4, &sc->sc_iaoq[1]);
192 err |= __put_user(regs->sr[3], &sc->sc_iasq[0]);
193 err |= __put_user(regs->sr[3], &sc->sc_iasq[1]);
194 DBG(1, "%s: iaoq %#lx / %#lx (in syscall)\n",
195 __func__, regs->gr[31], regs->gr[31]+4);
196 } else {
197 err |= __copy_to_user(sc->sc_iaoq, regs->iaoq, sizeof(regs->iaoq));
198 err |= __copy_to_user(sc->sc_iasq, regs->iasq, sizeof(regs->iasq));
199 DBG(1, "%s: iaoq %#lx / %#lx (not in syscall)\n",
200 __func__, regs->iaoq[0], regs->iaoq[1]);
201 }
202
203 err |= __put_user(flags, &sc->sc_flags);
204 err |= __copy_to_user(sc->sc_gr, regs->gr, sizeof(regs->gr));
205 err |= __copy_to_user(sc->sc_fr, regs->fr, sizeof(regs->fr));
206 err |= __put_user(regs->sar, &sc->sc_sar);
207 DBG(1, "%s: r28 is %ld\n", __func__, regs->gr[28]);
208
209 return err;
210}
211
212static long
213setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs,
214 long in_syscall)
215{
216 struct rt_sigframe __user *frame;
217 unsigned long rp, usp;
218 unsigned long haddr, sigframe_size;
219 unsigned long start;
220 int err = 0;
221#ifdef CONFIG_64BIT
222 struct compat_rt_sigframe __user * compat_frame;
223#endif
224
225 usp = (regs->gr[30] & ~(0x01UL));
226 sigframe_size = PARISC_RT_SIGFRAME_SIZE;
227#ifdef CONFIG_64BIT
228 if (is_compat_task()) {
229 /* The gcc alloca implementation leaves garbage in the upper 32 bits of sp */
230 usp = (compat_uint_t)usp;
231 sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
232 }
233#endif
234 frame = get_sigframe(&ksig->ka, usp, sigframe_size);
235
236 DBG(1, "%s: frame %p info %p\n", __func__, frame, &ksig->info);
237
238 start = (unsigned long) frame;
239 if (start >= TASK_SIZE_MAX - sigframe_size)
240 return -EFAULT;
241
242#ifdef CONFIG_64BIT
243
244 compat_frame = (struct compat_rt_sigframe __user *)frame;
245
246 if (is_compat_task()) {
247 DBG(1, "%s: frame->info = 0x%p\n", __func__, &compat_frame->info);
248 err |= copy_siginfo_to_user32(&compat_frame->info, &ksig->info);
249 err |= __compat_save_altstack( &compat_frame->uc.uc_stack, regs->gr[30]);
250 DBG(1, "%s: frame->uc = 0x%p\n", __func__, &compat_frame->uc);
251 DBG(1, "%s: frame->uc.uc_mcontext = 0x%p\n",
252 __func__, &compat_frame->uc.uc_mcontext);
253 err |= setup_sigcontext32(&compat_frame->uc.uc_mcontext,
254 &compat_frame->regs, regs, in_syscall);
255 err |= put_compat_sigset(&compat_frame->uc.uc_sigmask, set,
256 sizeof(compat_sigset_t));
257 } else
258#endif
259 {
260 DBG(1, "%s: frame->info = 0x%p\n", __func__, &frame->info);
261 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
262 err |= __save_altstack(&frame->uc.uc_stack, regs->gr[30]);
263 DBG(1, "%s: frame->uc = 0x%p\n", __func__, &frame->uc);
264 DBG(1, "%s: frame->uc.uc_mcontext = 0x%p\n",
265 __func__, &frame->uc.uc_mcontext);
266 err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, in_syscall);
267 /* FIXME: Should probably be converted as well for the compat case */
268 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
269 }
270
271 if (err)
272 return -EFAULT;
273
274#ifdef CONFIG_64BIT
275 if (!is_compat_task())
276 rp = VDSO64_SYMBOL(current, sigtramp_rt);
277 else
278#endif
279 rp = VDSO32_SYMBOL(current, sigtramp_rt);
280
281 if (in_syscall)
282 rp += 4*4; /* skip 4 instructions and start at ldi 1,%r25 */
283
284 haddr = A(ksig->ka.sa.sa_handler);
285 /* The sa_handler may be a pointer to a function descriptor */
286#ifdef CONFIG_64BIT
287 if (is_compat_task()) {
288#endif
289 if (haddr & PA_PLABEL_FDESC) {
290 Elf32_Fdesc fdesc;
291 Elf32_Fdesc __user *ufdesc = (Elf32_Fdesc __user *)A(haddr & ~3);
292
293 err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
294
295 if (err)
296 return -EFAULT;
297
298 haddr = fdesc.addr;
299 regs->gr[19] = fdesc.gp;
300 }
301#ifdef CONFIG_64BIT
302 } else {
303 Elf64_Fdesc fdesc;
304 Elf64_Fdesc __user *ufdesc = (Elf64_Fdesc __user *)A(haddr & ~3);
305
306 err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
307
308 if (err)
309 return -EFAULT;
310
311 haddr = fdesc.addr;
312 regs->gr[19] = fdesc.gp;
313 DBG(1, "%s: 64 bit signal, exe=%#lx, r19=%#lx, in_syscall=%d\n",
314 __func__, haddr, regs->gr[19], in_syscall);
315 }
316#endif
317
318 /* The syscall return path will create IAOQ values from r31.
319 */
320 if (in_syscall) {
321 regs->gr[31] = haddr;
322#ifdef CONFIG_64BIT
323 if (!test_thread_flag(TIF_32BIT))
324 sigframe_size |= 1; /* XXX ???? */
325#endif
326 } else {
327 unsigned long psw = USER_PSW;
328#ifdef CONFIG_64BIT
329 if (!test_thread_flag(TIF_32BIT))
330 psw |= PSW_W;
331#endif
332
333 /* If we are singlestepping, arrange a trap to be delivered
334 when we return to userspace. Note the semantics -- we
335 should trap before the first insn in the handler is
336 executed. Ref:
337 http://sources.redhat.com/ml/gdb/2004-11/msg00245.html
338 */
339 if (pa_psw(current)->r) {
340 pa_psw(current)->r = 0;
341 psw |= PSW_R;
342 mtctl(-1, 0);
343 }
344
345 regs->gr[0] = psw;
346 regs->iaoq[0] = haddr | PRIV_USER;
347 regs->iaoq[1] = regs->iaoq[0] + 4;
348 }
349
350 regs->gr[2] = rp; /* userland return pointer */
351 regs->gr[26] = ksig->sig; /* signal number */
352
353#ifdef CONFIG_64BIT
354 if (is_compat_task()) {
355 regs->gr[25] = A(&compat_frame->info); /* siginfo pointer */
356 regs->gr[24] = A(&compat_frame->uc); /* ucontext pointer */
357 } else
358#endif
359 {
360 regs->gr[25] = A(&frame->info); /* siginfo pointer */
361 regs->gr[24] = A(&frame->uc); /* ucontext pointer */
362 }
363
364 DBG(1, "%s: making sigreturn frame: %#lx + %#lx = %#lx\n", __func__,
365 regs->gr[30], sigframe_size,
366 regs->gr[30] + sigframe_size);
367 /* Raise the user stack pointer to make a proper call frame. */
368 regs->gr[30] = (A(frame) + sigframe_size);
369
370
371 DBG(1, "%s: sig deliver (%s,%d) frame=0x%p sp=%#lx iaoq=%#lx/%#lx rp=%#lx\n",
372 __func__, current->comm, current->pid, frame, regs->gr[30],
373 regs->iaoq[0], regs->iaoq[1], rp);
374
375 return 0;
376}
377
378/*
379 * OK, we're invoking a handler.
380 */
381
382static void
383handle_signal(struct ksignal *ksig, struct pt_regs *regs, long in_syscall)
384{
385 int ret;
386 sigset_t *oldset = sigmask_to_save();
387
388 DBG(1, "%s: sig=%d, ka=%p, info=%p, oldset=%p, regs=%p\n",
389 __func__, ksig->sig, &ksig->ka, &ksig->info, oldset, regs);
390
391 /* Set up the stack frame */
392 ret = setup_rt_frame(ksig, oldset, regs, in_syscall);
393
394 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP) ||
395 test_thread_flag(TIF_BLOCKSTEP));
396
397 DBG(1, "%s: Exit (success), regs->gr[28] = %ld\n",
398 __func__, regs->gr[28]);
399}
400
401/*
402 * Check how the syscall number gets loaded into %r20 within
403 * the delay branch in userspace and adjust as needed.
404 */
405
406static void check_syscallno_in_delay_branch(struct pt_regs *regs)
407{
408 u32 opcode, source_reg;
409 u32 __user *uaddr;
410 int err;
411
412 /* Usually we don't have to restore %r20 (the system call number)
413 * because it gets loaded in the delay slot of the branch external
414 * instruction via the ldi instruction.
415 * In some cases a register-to-register copy instruction might have
416 * been used instead, in which case we need to copy the syscall
417 * number into the source register before returning to userspace.
418 */
419
420 /* A syscall is just a branch, so all we have to do is fiddle the
421 * return pointer so that the ble instruction gets executed again.
422 */
423 regs->gr[31] -= 8; /* delayed branching */
424
425 /* Get assembler opcode of code in delay branch */
426 uaddr = (u32 __user *) ((regs->gr[31] & ~3) + 4);
427 err = get_user(opcode, uaddr);
428 if (err)
429 return;
430
431 /* Check if delay branch uses "ldi int,%r20" */
432 if ((opcode & 0xffff0000) == 0x34140000)
433 return; /* everything ok, just return */
434
435 /* Check if delay branch uses "nop" */
436 if (opcode == INSN_NOP)
437 return;
438
439 /* Check if delay branch uses "copy %rX,%r20" */
440 if ((opcode & 0xffe0ffff) == 0x08000254) {
441 source_reg = (opcode >> 16) & 31;
442 regs->gr[source_reg] = regs->gr[20];
443 return;
444 }
445
446 pr_warn("syscall restart: %s (pid %d): unexpected opcode 0x%08x\n",
447 current->comm, task_pid_nr(current), opcode);
448}
449
450static inline void
451syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
452{
453 if (regs->orig_r28)
454 return;
455 regs->orig_r28 = 1; /* no more restarts */
456
457 DBG(1, "%s: orig_r28 = %ld pid %d r20 %ld\n",
458 __func__, regs->orig_r28, task_pid_nr(current), regs->gr[20]);
459
460 /* Check the return code */
461 switch (regs->gr[28]) {
462 case -ERESTART_RESTARTBLOCK:
463 case -ERESTARTNOHAND:
464 DBG(1, "%s: ERESTARTNOHAND: returning -EINTR\n", __func__);
465 regs->gr[28] = -EINTR;
466 break;
467 case -ERESTARTSYS:
468 if (!(ka->sa.sa_flags & SA_RESTART)) {
469 DBG(1, "%s: ERESTARTSYS: putting -EINTR pid %d\n",
470 __func__, task_pid_nr(current));
471 regs->gr[28] = -EINTR;
472 break;
473 }
474 fallthrough;
475 case -ERESTARTNOINTR:
476 DBG(1, "%s: %ld\n", __func__, regs->gr[28]);
477 check_syscallno_in_delay_branch(regs);
478 break;
479 }
480}
481
482static inline void
483insert_restart_trampoline(struct pt_regs *regs)
484{
485 if (regs->orig_r28)
486 return;
487 regs->orig_r28 = 1; /* no more restarts */
488
489 DBG(2, "%s: gr28 = %ld pid %d\n",
490 __func__, regs->gr[28], task_pid_nr(current));
491
492 switch (regs->gr[28]) {
493 case -ERESTART_RESTARTBLOCK: {
494 /* Restart the system call - no handlers present */
495 unsigned int *usp = (unsigned int *)regs->gr[30];
496 unsigned long rp;
497 long err = 0;
498
499 /* check that we don't exceed the stack */
500 if (A(&usp[0]) >= TASK_SIZE_MAX - 5 * sizeof(int))
501 return;
502
503 /* Call trampoline in vdso to restart the syscall
504 * with __NR_restart_syscall.
505 * Original return addresses are on stack like this:
506 *
507 * 0: <return address (orig r31)>
508 * 4: <2nd half for 64-bit>
509 */
510#ifdef CONFIG_64BIT
511 if (!is_compat_task()) {
512 err |= put_user(regs->gr[31] >> 32, &usp[0]);
513 err |= put_user(regs->gr[31] & 0xffffffff, &usp[1]);
514 rp = VDSO64_SYMBOL(current, restart_syscall);
515 } else
516#endif
517 {
518 err |= put_user(regs->gr[31], &usp[0]);
519 rp = VDSO32_SYMBOL(current, restart_syscall);
520 }
521 WARN_ON(err);
522
523 regs->gr[31] = rp;
524 DBG(1, "%s: ERESTART_RESTARTBLOCK\n", __func__);
525 return;
526 }
527 case -EINTR:
528 /* ok, was handled before and should be returned. */
529 break;
530 case -ERESTARTNOHAND:
531 case -ERESTARTSYS:
532 case -ERESTARTNOINTR:
533 DBG(1, "%s: Type %ld\n", __func__, regs->gr[28]);
534 check_syscallno_in_delay_branch(regs);
535 return;
536 default:
537 break;
538 }
539}
540
541/*
542 * We need to be able to restore the syscall arguments (r21-r26) to
543 * restart syscalls. Thus, the syscall path should save them in the
544 * pt_regs structure (it's okay to do so since they are caller-save
545 * registers). As noted below, the syscall number gets restored for
546 * us due to the magic of delayed branching.
547 */
548static void do_signal(struct pt_regs *regs, long in_syscall)
549{
550 struct ksignal ksig;
551 int restart_syscall;
552 bool has_handler;
553
554 has_handler = get_signal(&ksig);
555
556 restart_syscall = 0;
557 if (in_syscall)
558 restart_syscall = 1;
559
560 if (has_handler) {
561 /* Restart a system call if necessary. */
562 if (restart_syscall)
563 syscall_restart(regs, &ksig.ka);
564
565 handle_signal(&ksig, regs, in_syscall);
566 DBG(1, "%s: Handled signal pid %d\n",
567 __func__, task_pid_nr(current));
568 return;
569 }
570
571 /* Do we need to restart the system call? */
572 if (restart_syscall)
573 insert_restart_trampoline(regs);
574
575 DBG(1, "%s: Exit (not delivered), regs->gr[28] = %ld orig_r28 = %ld pid %d\n",
576 __func__, regs->gr[28], regs->orig_r28, task_pid_nr(current));
577
578 restore_saved_sigmask();
579}
580
581asmlinkage void do_notify_resume(struct pt_regs *regs, long in_syscall)
582{
583 if (test_thread_flag(TIF_SIGPENDING) ||
584 test_thread_flag(TIF_NOTIFY_SIGNAL))
585 do_signal(regs, in_syscall);
586
587 if (test_thread_flag(TIF_NOTIFY_RESUME))
588 resume_user_mode_work(regs);
589}