xref: /openbmc/linux/arch/parisc/kernel/signal.c (revision 1c2dd16a)
1 /*
2  *  linux/arch/parisc/kernel/signal.c: Architecture-specific signal
3  *  handling support.
4  *
5  *  Copyright (C) 2000 David Huggins-Daines <dhd@debian.org>
6  *  Copyright (C) 2000 Linuxcare, Inc.
7  *
8  *  Based on the ia64, i386, and alpha versions.
9  *
10  *  Like the IA-64, we are a recent enough port (we are *starting*
11  *  with glibc2.2) that we do not need to support the old non-realtime
12  *  Linux signals.  Therefore we don't.
13  */
14 
15 #include <linux/sched.h>
16 #include <linux/sched/debug.h>
17 #include <linux/mm.h>
18 #include <linux/smp.h>
19 #include <linux/kernel.h>
20 #include <linux/signal.h>
21 #include <linux/errno.h>
22 #include <linux/wait.h>
23 #include <linux/ptrace.h>
24 #include <linux/tracehook.h>
25 #include <linux/unistd.h>
26 #include <linux/stddef.h>
27 #include <linux/compat.h>
28 #include <linux/elf.h>
29 #include <asm/ucontext.h>
30 #include <asm/rt_sigframe.h>
31 #include <linux/uaccess.h>
32 #include <asm/pgalloc.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 #define INSN_NOP	 0x08000240 /* nop */
68 /* For debugging */
69 #define INSN_DIE_HORRIBLY 0x68000ccc /* stw %r0,0x666(%sr0,%r0) */
70 
71 static long
72 restore_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 
87 void
88 sys_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 	compat_sigset_t compat_set;
96 	struct compat_rt_sigframe __user * compat_frame;
97 
98 	if (is_compat_task())
99 		sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
100 #endif
101 
102 	current->restart_block.fn = do_no_restart_syscall;
103 
104 	/* Unwind the user stack to get the rt_sigframe structure. */
105 	frame = (struct rt_sigframe __user *)
106 		(usp - sigframe_size);
107 	DBG(2,"sys_rt_sigreturn: frame is %p\n", frame);
108 
109 	regs->orig_r28 = 1; /* no restarts for sigreturn */
110 
111 #ifdef CONFIG_64BIT
112 	compat_frame = (struct compat_rt_sigframe __user *)frame;
113 
114 	if (is_compat_task()) {
115 		DBG(2,"sys_rt_sigreturn: ELF32 process.\n");
116 		if (__copy_from_user(&compat_set, &compat_frame->uc.uc_sigmask, sizeof(compat_set)))
117 			goto give_sigsegv;
118 		sigset_32to64(&set,&compat_set);
119 	} else
120 #endif
121 	{
122 		if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
123 			goto give_sigsegv;
124 	}
125 
126 	set_current_blocked(&set);
127 
128 	/* Good thing we saved the old gr[30], eh? */
129 #ifdef CONFIG_64BIT
130 	if (is_compat_task()) {
131 		DBG(1,"sys_rt_sigreturn: compat_frame->uc.uc_mcontext 0x%p\n",
132 				&compat_frame->uc.uc_mcontext);
133 // FIXME: Load upper half from register file
134 		if (restore_sigcontext32(&compat_frame->uc.uc_mcontext,
135 					&compat_frame->regs, regs))
136 			goto give_sigsegv;
137 		DBG(1,"sys_rt_sigreturn: usp %#08lx stack 0x%p\n",
138 				usp, &compat_frame->uc.uc_stack);
139 		if (compat_restore_altstack(&compat_frame->uc.uc_stack))
140 			goto give_sigsegv;
141 	} else
142 #endif
143 	{
144 		DBG(1,"sys_rt_sigreturn: frame->uc.uc_mcontext 0x%p\n",
145 				&frame->uc.uc_mcontext);
146 		if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
147 			goto give_sigsegv;
148 		DBG(1,"sys_rt_sigreturn: usp %#08lx stack 0x%p\n",
149 				usp, &frame->uc.uc_stack);
150 		if (restore_altstack(&frame->uc.uc_stack))
151 			goto give_sigsegv;
152 	}
153 
154 
155 
156 	/* If we are on the syscall path IAOQ will not be restored, and
157 	 * if we are on the interrupt path we must not corrupt gr31.
158 	 */
159 	if (in_syscall)
160 		regs->gr[31] = regs->iaoq[0];
161 #if DEBUG_SIG
162 	DBG(1,"sys_rt_sigreturn: returning to %#lx, DUMPING REGS:\n", regs->iaoq[0]);
163 	show_regs(regs);
164 #endif
165 	return;
166 
167 give_sigsegv:
168 	DBG(1,"sys_rt_sigreturn: Sending SIGSEGV\n");
169 	force_sig(SIGSEGV, current);
170 	return;
171 }
172 
173 /*
174  * Set up a signal frame.
175  */
176 
177 static inline void __user *
178 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
179 {
180 	/*FIXME: ELF32 vs. ELF64 has different frame_size, but since we
181 	  don't use the parameter it doesn't matter */
182 
183 	DBG(1,"get_sigframe: ka = %#lx, sp = %#lx, frame_size = %#lx\n",
184 			(unsigned long)ka, sp, frame_size);
185 
186 	/* Align alternate stack and reserve 64 bytes for the signal
187 	   handler's frame marker.  */
188 	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
189 		sp = (current->sas_ss_sp + 0x7f) & ~0x3f; /* Stacks grow up! */
190 
191 	DBG(1,"get_sigframe: Returning sp = %#lx\n", (unsigned long)sp);
192 	return (void __user *) sp; /* Stacks grow up.  Fun. */
193 }
194 
195 static long
196 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, int in_syscall)
197 
198 {
199 	unsigned long flags = 0;
200 	long err = 0;
201 
202 	if (on_sig_stack((unsigned long) sc))
203 		flags |= PARISC_SC_FLAG_ONSTACK;
204 	if (in_syscall) {
205 		flags |= PARISC_SC_FLAG_IN_SYSCALL;
206 		/* regs->iaoq is undefined in the syscall return path */
207 		err |= __put_user(regs->gr[31], &sc->sc_iaoq[0]);
208 		err |= __put_user(regs->gr[31]+4, &sc->sc_iaoq[1]);
209 		err |= __put_user(regs->sr[3], &sc->sc_iasq[0]);
210 		err |= __put_user(regs->sr[3], &sc->sc_iasq[1]);
211 		DBG(1,"setup_sigcontext: iaoq %#lx / %#lx (in syscall)\n",
212 			regs->gr[31], regs->gr[31]+4);
213 	} else {
214 		err |= __copy_to_user(sc->sc_iaoq, regs->iaoq, sizeof(regs->iaoq));
215 		err |= __copy_to_user(sc->sc_iasq, regs->iasq, sizeof(regs->iasq));
216 		DBG(1,"setup_sigcontext: iaoq %#lx / %#lx (not in syscall)\n",
217 			regs->iaoq[0], regs->iaoq[1]);
218 	}
219 
220 	err |= __put_user(flags, &sc->sc_flags);
221 	err |= __copy_to_user(sc->sc_gr, regs->gr, sizeof(regs->gr));
222 	err |= __copy_to_user(sc->sc_fr, regs->fr, sizeof(regs->fr));
223 	err |= __put_user(regs->sar, &sc->sc_sar);
224 	DBG(1,"setup_sigcontext: r28 is %ld\n", regs->gr[28]);
225 
226 	return err;
227 }
228 
229 static long
230 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs,
231 	       int in_syscall)
232 {
233 	struct rt_sigframe __user *frame;
234 	unsigned long rp, usp;
235 	unsigned long haddr, sigframe_size;
236 	unsigned long start, end;
237 	int err = 0;
238 #ifdef CONFIG_64BIT
239 	struct compat_rt_sigframe __user * compat_frame;
240 	compat_sigset_t compat_set;
241 #endif
242 
243 	usp = (regs->gr[30] & ~(0x01UL));
244 	/*FIXME: frame_size parameter is unused, remove it. */
245 	frame = get_sigframe(&ksig->ka, usp, sizeof(*frame));
246 
247 	DBG(1,"SETUP_RT_FRAME: START\n");
248 	DBG(1,"setup_rt_frame: frame %p info %p\n", frame, ksig->info);
249 
250 
251 #ifdef CONFIG_64BIT
252 
253 	compat_frame = (struct compat_rt_sigframe __user *)frame;
254 
255 	if (is_compat_task()) {
256 		DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &compat_frame->info);
257 		err |= copy_siginfo_to_user32(&compat_frame->info, &ksig->info);
258 		err |= __compat_save_altstack( &compat_frame->uc.uc_stack, regs->gr[30]);
259 		DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &compat_frame->uc);
260 		DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &compat_frame->uc.uc_mcontext);
261 		err |= setup_sigcontext32(&compat_frame->uc.uc_mcontext,
262 					&compat_frame->regs, regs, in_syscall);
263 		sigset_64to32(&compat_set,set);
264 		err |= __copy_to_user(&compat_frame->uc.uc_sigmask, &compat_set, sizeof(compat_set));
265 	} else
266 #endif
267 	{
268 		DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &frame->info);
269 		err |= copy_siginfo_to_user(&frame->info, &ksig->info);
270 		err |= __save_altstack(&frame->uc.uc_stack, regs->gr[30]);
271 		DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &frame->uc);
272 		DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &frame->uc.uc_mcontext);
273 		err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, in_syscall);
274 		/* FIXME: Should probably be converted as well for the compat case */
275 		err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
276 	}
277 
278 	if (err)
279 		return -EFAULT;
280 
281 	/* Set up to return from userspace.  If provided, use a stub
282 	   already in userspace. The first words of tramp are used to
283 	   save the previous sigrestartblock trampoline that might be
284 	   on the stack. We start the sigreturn trampoline at
285 	   SIGRESTARTBLOCK_TRAMP+X. */
286 	err |= __put_user(in_syscall ? INSN_LDI_R25_1 : INSN_LDI_R25_0,
287 			&frame->tramp[SIGRESTARTBLOCK_TRAMP+0]);
288 	err |= __put_user(INSN_LDI_R20,
289 			&frame->tramp[SIGRESTARTBLOCK_TRAMP+1]);
290 	err |= __put_user(INSN_BLE_SR2_R0,
291 			&frame->tramp[SIGRESTARTBLOCK_TRAMP+2]);
292 	err |= __put_user(INSN_NOP, &frame->tramp[SIGRESTARTBLOCK_TRAMP+3]);
293 
294 #if DEBUG_SIG
295 	/* Assert that we're flushing in the correct space... */
296 	{
297 		unsigned long sid;
298 		asm ("mfsp %%sr3,%0" : "=r" (sid));
299 		DBG(1,"setup_rt_frame: Flushing 64 bytes at space %#x offset %p\n",
300 		       sid, frame->tramp);
301 	}
302 #endif
303 
304 	start = (unsigned long) &frame->tramp[0];
305 	end = (unsigned long) &frame->tramp[TRAMP_SIZE];
306 	flush_user_dcache_range_asm(start, end);
307 	flush_user_icache_range_asm(start, end);
308 
309 	/* TRAMP Words 0-4, Length 5 = SIGRESTARTBLOCK_TRAMP
310 	 * TRAMP Words 5-9, Length 4 = SIGRETURN_TRAMP
311 	 * So the SIGRETURN_TRAMP is at the end of SIGRESTARTBLOCK_TRAMP
312 	 */
313 	rp = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP];
314 
315 	if (err)
316 		return -EFAULT;
317 
318 	haddr = A(ksig->ka.sa.sa_handler);
319 	/* The sa_handler may be a pointer to a function descriptor */
320 #ifdef CONFIG_64BIT
321 	if (is_compat_task()) {
322 #endif
323 		if (haddr & PA_PLABEL_FDESC) {
324 			Elf32_Fdesc fdesc;
325 			Elf32_Fdesc __user *ufdesc = (Elf32_Fdesc __user *)A(haddr & ~3);
326 
327 			err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
328 
329 			if (err)
330 				return -EFAULT;
331 
332 			haddr = fdesc.addr;
333 			regs->gr[19] = fdesc.gp;
334 		}
335 #ifdef CONFIG_64BIT
336 	} else {
337 		Elf64_Fdesc fdesc;
338 		Elf64_Fdesc __user *ufdesc = (Elf64_Fdesc __user *)A(haddr & ~3);
339 
340 		err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
341 
342 		if (err)
343 			return -EFAULT;
344 
345 		haddr = fdesc.addr;
346 		regs->gr[19] = fdesc.gp;
347 		DBG(1,"setup_rt_frame: 64 bit signal, exe=%#lx, r19=%#lx, in_syscall=%d\n",
348 		     haddr, regs->gr[19], in_syscall);
349 	}
350 #endif
351 
352 	/* The syscall return path will create IAOQ values from r31.
353 	 */
354 	sigframe_size = PARISC_RT_SIGFRAME_SIZE;
355 #ifdef CONFIG_64BIT
356 	if (is_compat_task())
357 		sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
358 #endif
359 	if (in_syscall) {
360 		regs->gr[31] = haddr;
361 #ifdef CONFIG_64BIT
362 		if (!test_thread_flag(TIF_32BIT))
363 			sigframe_size |= 1;
364 #endif
365 	} else {
366 		unsigned long psw = USER_PSW;
367 #ifdef CONFIG_64BIT
368 		if (!test_thread_flag(TIF_32BIT))
369 			psw |= PSW_W;
370 #endif
371 
372 		/* If we are singlestepping, arrange a trap to be delivered
373 		   when we return to userspace. Note the semantics -- we
374 		   should trap before the first insn in the handler is
375 		   executed. Ref:
376 			http://sources.redhat.com/ml/gdb/2004-11/msg00245.html
377 		 */
378 		if (pa_psw(current)->r) {
379 			pa_psw(current)->r = 0;
380 			psw |= PSW_R;
381 			mtctl(-1, 0);
382 		}
383 
384 		regs->gr[0] = psw;
385 		regs->iaoq[0] = haddr | 3;
386 		regs->iaoq[1] = regs->iaoq[0] + 4;
387 	}
388 
389 	regs->gr[2]  = rp;                /* userland return pointer */
390 	regs->gr[26] = ksig->sig;               /* signal number */
391 
392 #ifdef CONFIG_64BIT
393 	if (is_compat_task()) {
394 		regs->gr[25] = A(&compat_frame->info); /* siginfo pointer */
395 		regs->gr[24] = A(&compat_frame->uc);   /* ucontext pointer */
396 	} else
397 #endif
398 	{
399 		regs->gr[25] = A(&frame->info); /* siginfo pointer */
400 		regs->gr[24] = A(&frame->uc);   /* ucontext pointer */
401 	}
402 
403 	DBG(1,"setup_rt_frame: making sigreturn frame: %#lx + %#lx = %#lx\n",
404 	       regs->gr[30], sigframe_size,
405 	       regs->gr[30] + sigframe_size);
406 	/* Raise the user stack pointer to make a proper call frame. */
407 	regs->gr[30] = (A(frame) + sigframe_size);
408 
409 
410 	DBG(1,"setup_rt_frame: sig deliver (%s,%d) frame=0x%p sp=%#lx iaoq=%#lx/%#lx rp=%#lx\n",
411 	       current->comm, current->pid, frame, regs->gr[30],
412 	       regs->iaoq[0], regs->iaoq[1], rp);
413 
414 	return 0;
415 }
416 
417 /*
418  * OK, we're invoking a handler.
419  */
420 
421 static void
422 handle_signal(struct ksignal *ksig, struct pt_regs *regs, int in_syscall)
423 {
424 	int ret;
425 	sigset_t *oldset = sigmask_to_save();
426 
427 	DBG(1,"handle_signal: sig=%ld, ka=%p, info=%p, oldset=%p, regs=%p\n",
428 	       ksig->sig, ksig->ka, ksig->info, oldset, regs);
429 
430 	/* Set up the stack frame */
431 	ret = setup_rt_frame(ksig, oldset, regs, in_syscall);
432 
433 	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP) ||
434 			  test_thread_flag(TIF_BLOCKSTEP));
435 
436 	DBG(1,KERN_DEBUG "do_signal: Exit (success), regs->gr[28] = %ld\n",
437 		regs->gr[28]);
438 }
439 
440 /*
441  * Check how the syscall number gets loaded into %r20 within
442  * the delay branch in userspace and adjust as needed.
443  */
444 
445 static void check_syscallno_in_delay_branch(struct pt_regs *regs)
446 {
447 	u32 opcode, source_reg;
448 	u32 __user *uaddr;
449 	int err;
450 
451 	/* Usually we don't have to restore %r20 (the system call number)
452 	 * because it gets loaded in the delay slot of the branch external
453 	 * instruction via the ldi instruction.
454 	 * In some cases a register-to-register copy instruction might have
455 	 * been used instead, in which case we need to copy the syscall
456 	 * number into the source register before returning to userspace.
457 	 */
458 
459 	/* A syscall is just a branch, so all we have to do is fiddle the
460 	 * return pointer so that the ble instruction gets executed again.
461 	 */
462 	regs->gr[31] -= 8; /* delayed branching */
463 
464 	/* Get assembler opcode of code in delay branch */
465 	uaddr = (unsigned int *) ((regs->gr[31] & ~3) + 4);
466 	err = get_user(opcode, uaddr);
467 	if (err)
468 		return;
469 
470 	/* Check if delay branch uses "ldi int,%r20" */
471 	if ((opcode & 0xffff0000) == 0x34140000)
472 		return;	/* everything ok, just return */
473 
474 	/* Check if delay branch uses "nop" */
475 	if (opcode == INSN_NOP)
476 		return;
477 
478 	/* Check if delay branch uses "copy %rX,%r20" */
479 	if ((opcode & 0xffe0ffff) == 0x08000254) {
480 		source_reg = (opcode >> 16) & 31;
481 		regs->gr[source_reg] = regs->gr[20];
482 		return;
483 	}
484 
485 	pr_warn("syscall restart: %s (pid %d): unexpected opcode 0x%08x\n",
486 		current->comm, task_pid_nr(current), opcode);
487 }
488 
489 static inline void
490 syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
491 {
492 	if (regs->orig_r28)
493 		return;
494 	regs->orig_r28 = 1; /* no more restarts */
495 	/* Check the return code */
496 	switch (regs->gr[28]) {
497 	case -ERESTART_RESTARTBLOCK:
498 	case -ERESTARTNOHAND:
499 		DBG(1,"ERESTARTNOHAND: returning -EINTR\n");
500 		regs->gr[28] = -EINTR;
501 		break;
502 
503 	case -ERESTARTSYS:
504 		if (!(ka->sa.sa_flags & SA_RESTART)) {
505 			DBG(1,"ERESTARTSYS: putting -EINTR\n");
506 			regs->gr[28] = -EINTR;
507 			break;
508 		}
509 		/* fallthrough */
510 	case -ERESTARTNOINTR:
511 		check_syscallno_in_delay_branch(regs);
512 		break;
513 	}
514 }
515 
516 static inline void
517 insert_restart_trampoline(struct pt_regs *regs)
518 {
519 	if (regs->orig_r28)
520 		return;
521 	regs->orig_r28 = 1; /* no more restarts */
522 	switch(regs->gr[28]) {
523 	case -ERESTART_RESTARTBLOCK: {
524 		/* Restart the system call - no handlers present */
525 		unsigned int *usp = (unsigned int *)regs->gr[30];
526 		unsigned long start = (unsigned long) &usp[2];
527 		unsigned long end  = (unsigned long) &usp[5];
528 		long err = 0;
529 
530 		/* Setup a trampoline to restart the syscall
531 		 * with __NR_restart_syscall
532 		 *
533 		 *  0: <return address (orig r31)>
534 		 *  4: <2nd half for 64-bit>
535 		 *  8: ldw 0(%sp), %r31
536 		 * 12: be 0x100(%sr2, %r0)
537 		 * 16: ldi __NR_restart_syscall, %r20
538 		 */
539 #ifdef CONFIG_64BIT
540 		err |= put_user(regs->gr[31] >> 32, &usp[0]);
541 		err |= put_user(regs->gr[31] & 0xffffffff, &usp[1]);
542 		err |= put_user(0x0fc010df, &usp[2]);
543 #else
544 		err |= put_user(regs->gr[31], &usp[0]);
545 		err |= put_user(0x0fc0109f, &usp[2]);
546 #endif
547 		err |= put_user(0xe0008200, &usp[3]);
548 		err |= put_user(0x34140000, &usp[4]);
549 
550 		WARN_ON(err);
551 
552 		/* flush data/instruction cache for new insns */
553 		flush_user_dcache_range_asm(start, end);
554 		flush_user_icache_range_asm(start, end);
555 
556 		regs->gr[31] = regs->gr[30] + 8;
557 		return;
558 	}
559 	case -ERESTARTNOHAND:
560 	case -ERESTARTSYS:
561 	case -ERESTARTNOINTR:
562 		check_syscallno_in_delay_branch(regs);
563 		return;
564 	default:
565 		break;
566 	}
567 }
568 
569 /*
570  * Note that 'init' is a special process: it doesn't get signals it doesn't
571  * want to handle. Thus you cannot kill init even with a SIGKILL even by
572  * mistake.
573  *
574  * We need to be able to restore the syscall arguments (r21-r26) to
575  * restart syscalls.  Thus, the syscall path should save them in the
576  * pt_regs structure (it's okay to do so since they are caller-save
577  * registers).  As noted below, the syscall number gets restored for
578  * us due to the magic of delayed branching.
579  */
580 asmlinkage void
581 do_signal(struct pt_regs *regs, long in_syscall)
582 {
583 	struct ksignal ksig;
584 
585 	DBG(1,"\ndo_signal: regs=0x%p, sr7 %#lx, in_syscall=%d\n",
586 	       regs, regs->sr[7], in_syscall);
587 
588 	if (get_signal(&ksig)) {
589 		DBG(3,"do_signal: signr = %d, regs->gr[28] = %ld\n", signr, regs->gr[28]);
590 		/* Restart a system call if necessary. */
591 		if (in_syscall)
592 			syscall_restart(regs, &ksig.ka);
593 
594 		handle_signal(&ksig, regs, in_syscall);
595 		return;
596 	}
597 
598 	/* Did we come from a system call? */
599 	if (in_syscall)
600 		insert_restart_trampoline(regs);
601 
602 	DBG(1,"do_signal: Exit (not delivered), regs->gr[28] = %ld\n",
603 		regs->gr[28]);
604 
605 	restore_saved_sigmask();
606 }
607 
608 void do_notify_resume(struct pt_regs *regs, long in_syscall)
609 {
610 	if (test_thread_flag(TIF_SIGPENDING))
611 		do_signal(regs, in_syscall);
612 
613 	if (test_thread_flag(TIF_NOTIFY_RESUME)) {
614 		clear_thread_flag(TIF_NOTIFY_RESUME);
615 		tracehook_notify_resume(regs);
616 	}
617 }
618