xref: /openbmc/linux/arch/parisc/kernel/signal.c (revision 63705da3)
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/cacheflush.h>
34 #include <asm/asm-offsets.h>
35 
36 #ifdef CONFIG_COMPAT
37 #include "signal32.h"
38 #endif
39 
40 #define DEBUG_SIG 0
41 #define DEBUG_SIG_LEVEL 2
42 
43 #if DEBUG_SIG
44 #define DBG(LEVEL, ...) \
45         ((DEBUG_SIG_LEVEL >= LEVEL) \
46 	? printk(__VA_ARGS__) : (void) 0)
47 #else
48 #define DBG(LEVEL, ...)
49 #endif
50 
51 /* gcc will complain if a pointer is cast to an integer of different
52  * size.  If you really need to do this (and we do for an ELF32 user
53  * application in an ELF64 kernel) then you have to do a cast to an
54  * integer of the same size first.  The A() macro accomplishes
55  * this. */
56 #define A(__x)	((unsigned long)(__x))
57 
58 /*
59  * Do a signal return - restore sigcontext.
60  */
61 
62 /* Trampoline for calling rt_sigreturn() */
63 #define INSN_LDI_R25_0	 0x34190000 /* ldi  0,%r25 (in_syscall=0) */
64 #define INSN_LDI_R25_1	 0x34190002 /* ldi  1,%r25 (in_syscall=1) */
65 #define INSN_LDI_R20	 0x3414015a /* ldi  __NR_rt_sigreturn,%r20 */
66 #define INSN_BLE_SR2_R0  0xe4008200 /* be,l 0x100(%sr2,%r0),%sr0,%r31 */
67 /* For debugging */
68 #define INSN_DIE_HORRIBLY 0x68000ccc /* stw %r0,0x666(%sr0,%r0) */
69 
70 static long
71 restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
72 {
73 	long err = 0;
74 
75 	err |= __copy_from_user(regs->gr, sc->sc_gr, sizeof(regs->gr));
76 	err |= __copy_from_user(regs->fr, sc->sc_fr, sizeof(regs->fr));
77 	err |= __copy_from_user(regs->iaoq, sc->sc_iaoq, sizeof(regs->iaoq));
78 	err |= __copy_from_user(regs->iasq, sc->sc_iasq, sizeof(regs->iasq));
79 	err |= __get_user(regs->sar, &sc->sc_sar);
80 	DBG(2,"restore_sigcontext: iaoq is %#lx / %#lx\n",
81 			regs->iaoq[0],regs->iaoq[1]);
82 	DBG(2,"restore_sigcontext: r28 is %ld\n", regs->gr[28]);
83 	return err;
84 }
85 
86 void
87 sys_rt_sigreturn(struct pt_regs *regs, int in_syscall)
88 {
89 	struct rt_sigframe __user *frame;
90 	sigset_t set;
91 	unsigned long usp = (regs->gr[30] & ~(0x01UL));
92 	unsigned long sigframe_size = PARISC_RT_SIGFRAME_SIZE;
93 #ifdef CONFIG_64BIT
94 	struct compat_rt_sigframe __user * compat_frame;
95 
96 	if (is_compat_task())
97 		sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
98 #endif
99 
100 	current->restart_block.fn = do_no_restart_syscall;
101 
102 	/* Unwind the user stack to get the rt_sigframe structure. */
103 	frame = (struct rt_sigframe __user *)
104 		(usp - sigframe_size);
105 	DBG(2,"sys_rt_sigreturn: frame is %p\n", frame);
106 
107 	regs->orig_r28 = 1; /* no restarts for sigreturn */
108 
109 #ifdef CONFIG_64BIT
110 	compat_frame = (struct compat_rt_sigframe __user *)frame;
111 
112 	if (is_compat_task()) {
113 		DBG(2,"sys_rt_sigreturn: ELF32 process.\n");
114 		if (get_compat_sigset(&set, &compat_frame->uc.uc_sigmask))
115 			goto give_sigsegv;
116 	} else
117 #endif
118 	{
119 		if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
120 			goto give_sigsegv;
121 	}
122 
123 	set_current_blocked(&set);
124 
125 	/* Good thing we saved the old gr[30], eh? */
126 #ifdef CONFIG_64BIT
127 	if (is_compat_task()) {
128 		DBG(1,"sys_rt_sigreturn: compat_frame->uc.uc_mcontext 0x%p\n",
129 				&compat_frame->uc.uc_mcontext);
130 // FIXME: Load upper half from register file
131 		if (restore_sigcontext32(&compat_frame->uc.uc_mcontext,
132 					&compat_frame->regs, regs))
133 			goto give_sigsegv;
134 		DBG(1,"sys_rt_sigreturn: usp %#08lx stack 0x%p\n",
135 				usp, &compat_frame->uc.uc_stack);
136 		if (compat_restore_altstack(&compat_frame->uc.uc_stack))
137 			goto give_sigsegv;
138 	} else
139 #endif
140 	{
141 		DBG(1,"sys_rt_sigreturn: frame->uc.uc_mcontext 0x%p\n",
142 				&frame->uc.uc_mcontext);
143 		if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
144 			goto give_sigsegv;
145 		DBG(1,"sys_rt_sigreturn: usp %#08lx stack 0x%p\n",
146 				usp, &frame->uc.uc_stack);
147 		if (restore_altstack(&frame->uc.uc_stack))
148 			goto give_sigsegv;
149 	}
150 
151 
152 
153 	/* If we are on the syscall path IAOQ will not be restored, and
154 	 * if we are on the interrupt path we must not corrupt gr31.
155 	 */
156 	if (in_syscall)
157 		regs->gr[31] = regs->iaoq[0];
158 #if DEBUG_SIG
159 	DBG(1,"sys_rt_sigreturn: returning to %#lx, DUMPING REGS:\n", regs->iaoq[0]);
160 	show_regs(regs);
161 #endif
162 	return;
163 
164 give_sigsegv:
165 	DBG(1,"sys_rt_sigreturn: Sending SIGSEGV\n");
166 	force_sig(SIGSEGV);
167 	return;
168 }
169 
170 /*
171  * Set up a signal frame.
172  */
173 
174 static inline void __user *
175 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
176 {
177 	/*FIXME: ELF32 vs. ELF64 has different frame_size, but since we
178 	  don't use the parameter it doesn't matter */
179 
180 	DBG(1,"get_sigframe: ka = %#lx, sp = %#lx, frame_size = %#lx\n",
181 			(unsigned long)ka, sp, frame_size);
182 
183 	/* Align alternate stack and reserve 64 bytes for the signal
184 	   handler's frame marker.  */
185 	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
186 		sp = (current->sas_ss_sp + 0x7f) & ~0x3f; /* Stacks grow up! */
187 
188 	DBG(1,"get_sigframe: Returning sp = %#lx\n", (unsigned long)sp);
189 	return (void __user *) sp; /* Stacks grow up.  Fun. */
190 }
191 
192 static long
193 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, int in_syscall)
194 
195 {
196 	unsigned long flags = 0;
197 	long err = 0;
198 
199 	if (on_sig_stack((unsigned long) sc))
200 		flags |= PARISC_SC_FLAG_ONSTACK;
201 	if (in_syscall) {
202 		flags |= PARISC_SC_FLAG_IN_SYSCALL;
203 		/* regs->iaoq is undefined in the syscall return path */
204 		err |= __put_user(regs->gr[31], &sc->sc_iaoq[0]);
205 		err |= __put_user(regs->gr[31]+4, &sc->sc_iaoq[1]);
206 		err |= __put_user(regs->sr[3], &sc->sc_iasq[0]);
207 		err |= __put_user(regs->sr[3], &sc->sc_iasq[1]);
208 		DBG(1,"setup_sigcontext: iaoq %#lx / %#lx (in syscall)\n",
209 			regs->gr[31], regs->gr[31]+4);
210 	} else {
211 		err |= __copy_to_user(sc->sc_iaoq, regs->iaoq, sizeof(regs->iaoq));
212 		err |= __copy_to_user(sc->sc_iasq, regs->iasq, sizeof(regs->iasq));
213 		DBG(1,"setup_sigcontext: iaoq %#lx / %#lx (not in syscall)\n",
214 			regs->iaoq[0], regs->iaoq[1]);
215 	}
216 
217 	err |= __put_user(flags, &sc->sc_flags);
218 	err |= __copy_to_user(sc->sc_gr, regs->gr, sizeof(regs->gr));
219 	err |= __copy_to_user(sc->sc_fr, regs->fr, sizeof(regs->fr));
220 	err |= __put_user(regs->sar, &sc->sc_sar);
221 	DBG(1,"setup_sigcontext: r28 is %ld\n", regs->gr[28]);
222 
223 	return err;
224 }
225 
226 static long
227 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs,
228 	       int in_syscall)
229 {
230 	struct rt_sigframe __user *frame;
231 	unsigned long rp, usp;
232 	unsigned long haddr, sigframe_size;
233 	unsigned long start, end;
234 	int err = 0;
235 #ifdef CONFIG_64BIT
236 	struct compat_rt_sigframe __user * compat_frame;
237 #endif
238 
239 	usp = (regs->gr[30] & ~(0x01UL));
240 	sigframe_size = PARISC_RT_SIGFRAME_SIZE;
241 #ifdef CONFIG_64BIT
242 	if (is_compat_task()) {
243 		/* The gcc alloca implementation leaves garbage in the upper 32 bits of sp */
244 		usp = (compat_uint_t)usp;
245 		sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
246 	}
247 #endif
248 	frame = get_sigframe(&ksig->ka, usp, sigframe_size);
249 
250 	DBG(1,"SETUP_RT_FRAME: START\n");
251 	DBG(1,"setup_rt_frame: frame %p info %p\n", frame, ksig->info);
252 
253 	start = (unsigned long) frame;
254 	if (start >= user_addr_max() - sigframe_size)
255 		return -EFAULT;
256 
257 #ifdef CONFIG_64BIT
258 
259 	compat_frame = (struct compat_rt_sigframe __user *)frame;
260 
261 	if (is_compat_task()) {
262 		DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &compat_frame->info);
263 		err |= copy_siginfo_to_user32(&compat_frame->info, &ksig->info);
264 		err |= __compat_save_altstack( &compat_frame->uc.uc_stack, regs->gr[30]);
265 		DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &compat_frame->uc);
266 		DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &compat_frame->uc.uc_mcontext);
267 		err |= setup_sigcontext32(&compat_frame->uc.uc_mcontext,
268 					&compat_frame->regs, regs, in_syscall);
269 		err |= put_compat_sigset(&compat_frame->uc.uc_sigmask, set,
270 					 sizeof(compat_sigset_t));
271 	} else
272 #endif
273 	{
274 		DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &frame->info);
275 		err |= copy_siginfo_to_user(&frame->info, &ksig->info);
276 		err |= __save_altstack(&frame->uc.uc_stack, regs->gr[30]);
277 		DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &frame->uc);
278 		DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &frame->uc.uc_mcontext);
279 		err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, in_syscall);
280 		/* FIXME: Should probably be converted as well for the compat case */
281 		err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
282 	}
283 
284 	if (err)
285 		return -EFAULT;
286 
287 	/* Set up to return from userspace.  If provided, use a stub
288 	   already in userspace. The first words of tramp are used to
289 	   save the previous sigrestartblock trampoline that might be
290 	   on the stack. We start the sigreturn trampoline at
291 	   SIGRESTARTBLOCK_TRAMP. */
292 	err |= __put_user(in_syscall ? INSN_LDI_R25_1 : INSN_LDI_R25_0,
293 			&frame->tramp[SIGRESTARTBLOCK_TRAMP+0]);
294 	err |= __put_user(INSN_BLE_SR2_R0,
295 			&frame->tramp[SIGRESTARTBLOCK_TRAMP+1]);
296 	err |= __put_user(INSN_LDI_R20,
297 			&frame->tramp[SIGRESTARTBLOCK_TRAMP+2]);
298 
299 	start = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP+0];
300 	end = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP+3];
301 	flush_user_dcache_range_asm(start, end);
302 	flush_user_icache_range_asm(start, end);
303 
304 	/* TRAMP Words 0-4, Length 5 = SIGRESTARTBLOCK_TRAMP
305 	 * TRAMP Words 5-7, Length 3 = SIGRETURN_TRAMP
306 	 * So the SIGRETURN_TRAMP is at the end of SIGRESTARTBLOCK_TRAMP
307 	 */
308 	rp = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP];
309 
310 	if (err)
311 		return -EFAULT;
312 
313 	haddr = A(ksig->ka.sa.sa_handler);
314 	/* The sa_handler may be a pointer to a function descriptor */
315 #ifdef CONFIG_64BIT
316 	if (is_compat_task()) {
317 #endif
318 		if (haddr & PA_PLABEL_FDESC) {
319 			Elf32_Fdesc fdesc;
320 			Elf32_Fdesc __user *ufdesc = (Elf32_Fdesc __user *)A(haddr & ~3);
321 
322 			err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
323 
324 			if (err)
325 				return -EFAULT;
326 
327 			haddr = fdesc.addr;
328 			regs->gr[19] = fdesc.gp;
329 		}
330 #ifdef CONFIG_64BIT
331 	} else {
332 		Elf64_Fdesc fdesc;
333 		Elf64_Fdesc __user *ufdesc = (Elf64_Fdesc __user *)A(haddr & ~3);
334 
335 		err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
336 
337 		if (err)
338 			return -EFAULT;
339 
340 		haddr = fdesc.addr;
341 		regs->gr[19] = fdesc.gp;
342 		DBG(1,"setup_rt_frame: 64 bit signal, exe=%#lx, r19=%#lx, in_syscall=%d\n",
343 		     haddr, regs->gr[19], in_syscall);
344 	}
345 #endif
346 
347 	/* The syscall return path will create IAOQ values from r31.
348 	 */
349 	if (in_syscall) {
350 		regs->gr[31] = haddr;
351 #ifdef CONFIG_64BIT
352 		if (!test_thread_flag(TIF_32BIT))
353 			sigframe_size |= 1;
354 #endif
355 	} else {
356 		unsigned long psw = USER_PSW;
357 #ifdef CONFIG_64BIT
358 		if (!test_thread_flag(TIF_32BIT))
359 			psw |= PSW_W;
360 #endif
361 
362 		/* If we are singlestepping, arrange a trap to be delivered
363 		   when we return to userspace. Note the semantics -- we
364 		   should trap before the first insn in the handler is
365 		   executed. Ref:
366 			http://sources.redhat.com/ml/gdb/2004-11/msg00245.html
367 		 */
368 		if (pa_psw(current)->r) {
369 			pa_psw(current)->r = 0;
370 			psw |= PSW_R;
371 			mtctl(-1, 0);
372 		}
373 
374 		regs->gr[0] = psw;
375 		regs->iaoq[0] = haddr | 3;
376 		regs->iaoq[1] = regs->iaoq[0] + 4;
377 	}
378 
379 	regs->gr[2]  = rp;                /* userland return pointer */
380 	regs->gr[26] = ksig->sig;               /* signal number */
381 
382 #ifdef CONFIG_64BIT
383 	if (is_compat_task()) {
384 		regs->gr[25] = A(&compat_frame->info); /* siginfo pointer */
385 		regs->gr[24] = A(&compat_frame->uc);   /* ucontext pointer */
386 	} else
387 #endif
388 	{
389 		regs->gr[25] = A(&frame->info); /* siginfo pointer */
390 		regs->gr[24] = A(&frame->uc);   /* ucontext pointer */
391 	}
392 
393 	DBG(1,"setup_rt_frame: making sigreturn frame: %#lx + %#lx = %#lx\n",
394 	       regs->gr[30], sigframe_size,
395 	       regs->gr[30] + sigframe_size);
396 	/* Raise the user stack pointer to make a proper call frame. */
397 	regs->gr[30] = (A(frame) + sigframe_size);
398 
399 
400 	DBG(1,"setup_rt_frame: sig deliver (%s,%d) frame=0x%p sp=%#lx iaoq=%#lx/%#lx rp=%#lx\n",
401 	       current->comm, current->pid, frame, regs->gr[30],
402 	       regs->iaoq[0], regs->iaoq[1], rp);
403 
404 	return 0;
405 }
406 
407 /*
408  * OK, we're invoking a handler.
409  */
410 
411 static void
412 handle_signal(struct ksignal *ksig, struct pt_regs *regs, int in_syscall)
413 {
414 	int ret;
415 	sigset_t *oldset = sigmask_to_save();
416 
417 	DBG(1,"handle_signal: sig=%ld, ka=%p, info=%p, oldset=%p, regs=%p\n",
418 	       ksig->sig, ksig->ka, ksig->info, oldset, regs);
419 
420 	/* Set up the stack frame */
421 	ret = setup_rt_frame(ksig, oldset, regs, in_syscall);
422 
423 	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP) ||
424 			  test_thread_flag(TIF_BLOCKSTEP));
425 
426 	DBG(1,KERN_DEBUG "do_signal: Exit (success), regs->gr[28] = %ld\n",
427 		regs->gr[28]);
428 }
429 
430 /*
431  * Check how the syscall number gets loaded into %r20 within
432  * the delay branch in userspace and adjust as needed.
433  */
434 
435 static void check_syscallno_in_delay_branch(struct pt_regs *regs)
436 {
437 	u32 opcode, source_reg;
438 	u32 __user *uaddr;
439 	int err;
440 
441 	/* Usually we don't have to restore %r20 (the system call number)
442 	 * because it gets loaded in the delay slot of the branch external
443 	 * instruction via the ldi instruction.
444 	 * In some cases a register-to-register copy instruction might have
445 	 * been used instead, in which case we need to copy the syscall
446 	 * number into the source register before returning to userspace.
447 	 */
448 
449 	/* A syscall is just a branch, so all we have to do is fiddle the
450 	 * return pointer so that the ble instruction gets executed again.
451 	 */
452 	regs->gr[31] -= 8; /* delayed branching */
453 
454 	/* Get assembler opcode of code in delay branch */
455 	uaddr = (unsigned int *) ((regs->gr[31] & ~3) + 4);
456 	err = get_user(opcode, uaddr);
457 	if (err)
458 		return;
459 
460 	/* Check if delay branch uses "ldi int,%r20" */
461 	if ((opcode & 0xffff0000) == 0x34140000)
462 		return;	/* everything ok, just return */
463 
464 	/* Check if delay branch uses "nop" */
465 	if (opcode == INSN_NOP)
466 		return;
467 
468 	/* Check if delay branch uses "copy %rX,%r20" */
469 	if ((opcode & 0xffe0ffff) == 0x08000254) {
470 		source_reg = (opcode >> 16) & 31;
471 		regs->gr[source_reg] = regs->gr[20];
472 		return;
473 	}
474 
475 	pr_warn("syscall restart: %s (pid %d): unexpected opcode 0x%08x\n",
476 		current->comm, task_pid_nr(current), opcode);
477 }
478 
479 static inline void
480 syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
481 {
482 	if (regs->orig_r28)
483 		return;
484 	regs->orig_r28 = 1; /* no more restarts */
485 	/* Check the return code */
486 	switch (regs->gr[28]) {
487 	case -ERESTART_RESTARTBLOCK:
488 	case -ERESTARTNOHAND:
489 		DBG(1,"ERESTARTNOHAND: returning -EINTR\n");
490 		regs->gr[28] = -EINTR;
491 		break;
492 	case -ERESTARTSYS:
493 		if (!(ka->sa.sa_flags & SA_RESTART)) {
494 			DBG(1,"ERESTARTSYS: putting -EINTR\n");
495 			regs->gr[28] = -EINTR;
496 			break;
497 		}
498 		fallthrough;
499 	case -ERESTARTNOINTR:
500 		check_syscallno_in_delay_branch(regs);
501 		break;
502 	}
503 }
504 
505 static inline void
506 insert_restart_trampoline(struct pt_regs *regs)
507 {
508 	if (regs->orig_r28)
509 		return;
510 	regs->orig_r28 = 1; /* no more restarts */
511 	switch(regs->gr[28]) {
512 	case -ERESTART_RESTARTBLOCK: {
513 		/* Restart the system call - no handlers present */
514 		unsigned int *usp = (unsigned int *)regs->gr[30];
515 		unsigned long start = (unsigned long) &usp[2];
516 		unsigned long end  = (unsigned long) &usp[5];
517 		long err = 0;
518 
519 		/* check that we don't exceed the stack */
520 		if (A(&usp[0]) >= user_addr_max() - 5 * sizeof(int))
521 			return;
522 
523 		/* Setup a trampoline to restart the syscall
524 		 * with __NR_restart_syscall
525 		 *
526 		 *  0: <return address (orig r31)>
527 		 *  4: <2nd half for 64-bit>
528 		 *  8: ldw 0(%sp), %r31
529 		 * 12: be 0x100(%sr2, %r0)
530 		 * 16: ldi __NR_restart_syscall, %r20
531 		 */
532 #ifdef CONFIG_64BIT
533 		err |= put_user(regs->gr[31] >> 32, &usp[0]);
534 		err |= put_user(regs->gr[31] & 0xffffffff, &usp[1]);
535 		err |= put_user(0x0fc010df, &usp[2]);
536 #else
537 		err |= put_user(regs->gr[31], &usp[0]);
538 		err |= put_user(0x0fc0109f, &usp[2]);
539 #endif
540 		err |= put_user(0xe0008200, &usp[3]);
541 		err |= put_user(0x34140000, &usp[4]);
542 
543 		WARN_ON(err);
544 
545 		/* flush data/instruction cache for new insns */
546 		flush_user_dcache_range_asm(start, end);
547 		flush_user_icache_range_asm(start, end);
548 
549 		regs->gr[31] = regs->gr[30] + 8;
550 		return;
551 	}
552 	case -ERESTARTNOHAND:
553 	case -ERESTARTSYS:
554 	case -ERESTARTNOINTR:
555 		check_syscallno_in_delay_branch(regs);
556 		return;
557 	default:
558 		break;
559 	}
560 }
561 
562 /*
563  * We need to be able to restore the syscall arguments (r21-r26) to
564  * restart syscalls.  Thus, the syscall path should save them in the
565  * pt_regs structure (it's okay to do so since they are caller-save
566  * registers).  As noted below, the syscall number gets restored for
567  * us due to the magic of delayed branching.
568  */
569 asmlinkage void
570 do_signal(struct pt_regs *regs, long in_syscall)
571 {
572 	struct ksignal ksig;
573 
574 	DBG(1,"\ndo_signal: regs=0x%p, sr7 %#lx, in_syscall=%d\n",
575 	       regs, regs->sr[7], in_syscall);
576 
577 	if (get_signal(&ksig)) {
578 		DBG(3,"do_signal: signr = %d, regs->gr[28] = %ld\n", signr, regs->gr[28]);
579 		/* Restart a system call if necessary. */
580 		if (in_syscall)
581 			syscall_restart(regs, &ksig.ka);
582 
583 		handle_signal(&ksig, regs, in_syscall);
584 		return;
585 	}
586 
587 	/* Did we come from a system call? */
588 	if (in_syscall)
589 		insert_restart_trampoline(regs);
590 
591 	DBG(1,"do_signal: Exit (not delivered), regs->gr[28] = %ld\n",
592 		regs->gr[28]);
593 
594 	restore_saved_sigmask();
595 }
596 
597 void do_notify_resume(struct pt_regs *regs, long in_syscall)
598 {
599 	if (test_thread_flag(TIF_SIGPENDING) ||
600 	    test_thread_flag(TIF_NOTIFY_SIGNAL))
601 		do_signal(regs, in_syscall);
602 
603 	if (test_thread_flag(TIF_NOTIFY_RESUME))
604 		tracehook_notify_resume(regs);
605 }
606