1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright IBM Corp. 1999, 2006
4 * Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
6 * Based on Intel version
8 * Copyright (C) 1991, 1992 Linus Torvalds
10 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
13 #include <linux/sched.h>
14 #include <linux/sched/task_stack.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/unistd.h>
23 #include <linux/stddef.h>
24 #include <linux/tty.h>
25 #include <linux/personality.h>
26 #include <linux/binfmts.h>
27 #include <linux/tracehook.h>
28 #include <linux/syscalls.h>
29 #include <linux/compat.h>
30 #include <asm/ucontext.h>
31 #include <linux/uaccess.h>
32 #include <asm/lowcore.h>
33 #include <asm/switch_to.h>
37 * Layout of an old-style signal-frame:
38 * -----------------------------------------
39 * | save area (_SIGNAL_FRAMESIZE) |
40 * -----------------------------------------
41 * | struct sigcontext |
44 * -----------------------------------------
46 * | _s390_regs_common |
48 * -----------------------------------------
50 * -----------------------------------------
51 * | _sigregs_ext with |
52 * | gprs_high 64 byte (opt) |
53 * | vxrs_low 128 byte (opt) |
54 * | vxrs_high 256 byte (opt) |
55 * | reserved 128 byte (opt) |
56 * -----------------------------------------
58 * -----------------------------------------
59 * The svc_insn entry with the sigreturn system call opcode does not
60 * have a fixed position and moves if gprs_high or vxrs exist.
61 * Future extensions will be added to _sigregs_ext.
65 __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
69 _sigregs_ext sregs_ext;
70 __u16 svc_insn; /* Offset of svc_insn is NOT fixed! */
74 * Layout of an rt signal-frame:
75 * -----------------------------------------
76 * | save area (_SIGNAL_FRAMESIZE) |
77 * -----------------------------------------
78 * | svc __NR_rt_sigreturn 2 byte |
79 * -----------------------------------------
81 * -----------------------------------------
82 * | struct ucontext_extended with |
83 * | unsigned long uc_flags |
84 * | struct ucontext *uc_link |
85 * | stack_t uc_stack |
86 * | _sigregs uc_mcontext with |
87 * | _s390_regs_common |
89 * | sigset_t uc_sigmask |
90 * | _sigregs_ext uc_mcontext_ext |
91 * | gprs_high 64 byte (opt) |
92 * | vxrs_low 128 byte (opt) |
93 * | vxrs_high 256 byte (opt)|
94 * | reserved 128 byte (opt) |
95 * -----------------------------------------
96 * Future extensions will be added to _sigregs_ext.
100 __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
103 struct ucontext_extended uc;
106 /* Store registers needed to create the signal frame */
107 static void store_sigregs(void)
109 save_access_regs(current->thread.acrs);
113 /* Load registers after signal return */
114 static void load_sigregs(void)
116 restore_access_regs(current->thread.acrs);
119 /* Returns non-zero on fault. */
120 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
124 /* Copy a 'clean' PSW mask to the user to avoid leaking
125 information about whether PER is currently on. */
126 user_sregs.regs.psw.mask = PSW_USER_BITS |
127 (regs->psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
128 user_sregs.regs.psw.addr = regs->psw.addr;
129 memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs));
130 memcpy(&user_sregs.regs.acrs, current->thread.acrs,
131 sizeof(user_sregs.regs.acrs));
132 fpregs_store(&user_sregs.fpregs, ¤t->thread.fpu);
133 if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs)))
138 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
142 /* Alwys make any pending restarted system call return -EINTR */
143 current->restart_block.fn = do_no_restart_syscall;
145 if (__copy_from_user(&user_sregs, sregs, sizeof(user_sregs)))
148 if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI))
151 /* Test the floating-point-control word. */
152 if (test_fp_ctl(user_sregs.fpregs.fpc))
155 /* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
156 regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) |
157 (user_sregs.regs.psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
158 /* Check for invalid user address space control. */
159 if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
160 regs->psw.mask = PSW_ASC_PRIMARY |
161 (regs->psw.mask & ~PSW_MASK_ASC);
162 /* Check for invalid amode */
163 if (regs->psw.mask & PSW_MASK_EA)
164 regs->psw.mask |= PSW_MASK_BA;
165 regs->psw.addr = user_sregs.regs.psw.addr;
166 memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
167 memcpy(¤t->thread.acrs, &user_sregs.regs.acrs,
168 sizeof(current->thread.acrs));
170 fpregs_load(&user_sregs.fpregs, ¤t->thread.fpu);
172 clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
173 clear_pt_regs_flag(regs, PIF_SYSCALL_RESTART);
177 /* Returns non-zero on fault. */
178 static int save_sigregs_ext(struct pt_regs *regs,
179 _sigregs_ext __user *sregs_ext)
181 __u64 vxrs[__NUM_VXRS_LOW];
184 /* Save vector registers to signal stack */
185 if (MACHINE_HAS_VX) {
186 for (i = 0; i < __NUM_VXRS_LOW; i++)
187 vxrs[i] = *((__u64 *)(current->thread.fpu.vxrs + i) + 1);
188 if (__copy_to_user(&sregs_ext->vxrs_low, vxrs,
189 sizeof(sregs_ext->vxrs_low)) ||
190 __copy_to_user(&sregs_ext->vxrs_high,
191 current->thread.fpu.vxrs + __NUM_VXRS_LOW,
192 sizeof(sregs_ext->vxrs_high)))
198 static int restore_sigregs_ext(struct pt_regs *regs,
199 _sigregs_ext __user *sregs_ext)
201 __u64 vxrs[__NUM_VXRS_LOW];
204 /* Restore vector registers from signal stack */
205 if (MACHINE_HAS_VX) {
206 if (__copy_from_user(vxrs, &sregs_ext->vxrs_low,
207 sizeof(sregs_ext->vxrs_low)) ||
208 __copy_from_user(current->thread.fpu.vxrs + __NUM_VXRS_LOW,
209 &sregs_ext->vxrs_high,
210 sizeof(sregs_ext->vxrs_high)))
212 for (i = 0; i < __NUM_VXRS_LOW; i++)
213 *((__u64 *)(current->thread.fpu.vxrs + i) + 1) = vxrs[i];
218 SYSCALL_DEFINE0(sigreturn)
220 struct pt_regs *regs = task_pt_regs(current);
221 struct sigframe __user *frame =
222 (struct sigframe __user *) regs->gprs[15];
225 if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
227 set_current_blocked(&set);
229 if (restore_sigregs(regs, &frame->sregs))
231 if (restore_sigregs_ext(regs, &frame->sregs_ext))
234 return regs->gprs[2];
240 SYSCALL_DEFINE0(rt_sigreturn)
242 struct pt_regs *regs = task_pt_regs(current);
243 struct rt_sigframe __user *frame =
244 (struct rt_sigframe __user *)regs->gprs[15];
247 if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
249 set_current_blocked(&set);
250 if (restore_altstack(&frame->uc.uc_stack))
253 if (restore_sigregs(regs, &frame->uc.uc_mcontext))
255 if (restore_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
258 return regs->gprs[2];
265 * Determine which stack to use..
267 static inline void __user *
268 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
272 /* Default to using normal stack */
275 /* Overflow on alternate signal stack gives SIGSEGV. */
276 if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
277 return (void __user *) -1UL;
279 /* This is the X/Open sanctioned signal stack switching. */
280 if (ka->sa.sa_flags & SA_ONSTACK) {
281 if (! sas_ss_flags(sp))
282 sp = current->sas_ss_sp + current->sas_ss_size;
285 return (void __user *)((sp - frame_size) & -8ul);
288 static int setup_frame(int sig, struct k_sigaction *ka,
289 sigset_t *set, struct pt_regs * regs)
291 struct sigframe __user *frame;
292 struct sigcontext sc;
293 unsigned long restorer;
297 * gprs_high are only present for a 31-bit task running on
298 * a 64-bit kernel (see compat_signal.c) but the space for
299 * gprs_high need to be allocated if vector registers are
300 * included in the signal frame on a 31-bit system.
302 frame_size = sizeof(*frame) - sizeof(frame->sregs_ext);
304 frame_size += sizeof(frame->sregs_ext);
305 frame = get_sigframe(ka, regs, frame_size);
306 if (frame == (void __user *) -1UL)
309 /* Set up backchain. */
310 if (__put_user(regs->gprs[15], (addr_t __user *) frame))
313 /* Create struct sigcontext on the signal stack */
314 memcpy(&sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE);
315 sc.sregs = (_sigregs __user __force *) &frame->sregs;
316 if (__copy_to_user(&frame->sc, &sc, sizeof(frame->sc)))
319 /* Store registers needed to create the signal frame */
322 /* Create _sigregs on the signal stack */
323 if (save_sigregs(regs, &frame->sregs))
326 /* Place signal number on stack to allow backtrace from handler. */
327 if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
330 /* Create _sigregs_ext on the signal stack */
331 if (save_sigregs_ext(regs, &frame->sregs_ext))
334 /* Set up to return from userspace. If provided, use a stub
335 already in userspace. */
336 if (ka->sa.sa_flags & SA_RESTORER) {
337 restorer = (unsigned long) ka->sa.sa_restorer;
339 /* Signal frame without vector registers are short ! */
340 __u16 __user *svc = (void __user *) frame + frame_size - 2;
341 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc))
343 restorer = (unsigned long) svc;
346 /* Set up registers for signal handler */
347 regs->gprs[14] = restorer;
348 regs->gprs[15] = (unsigned long) frame;
349 /* Force default amode and default user address space control. */
350 regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
351 (PSW_USER_BITS & PSW_MASK_ASC) |
352 (regs->psw.mask & ~PSW_MASK_ASC);
353 regs->psw.addr = (unsigned long) ka->sa.sa_handler;
356 regs->gprs[3] = (unsigned long) &frame->sc;
358 /* We forgot to include these in the sigcontext.
359 To avoid breaking binary compatibility, they are passed as args. */
360 if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
361 sig == SIGTRAP || sig == SIGFPE) {
362 /* set extra registers only for synchronous signals */
363 regs->gprs[4] = regs->int_code & 127;
364 regs->gprs[5] = regs->int_parm_long;
365 regs->gprs[6] = current->thread.last_break;
370 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
371 struct pt_regs *regs)
373 struct rt_sigframe __user *frame;
374 unsigned long uc_flags, restorer;
377 frame_size = sizeof(struct rt_sigframe) - sizeof(_sigregs_ext);
379 * gprs_high are only present for a 31-bit task running on
380 * a 64-bit kernel (see compat_signal.c) but the space for
381 * gprs_high need to be allocated if vector registers are
382 * included in the signal frame on a 31-bit system.
385 if (MACHINE_HAS_VX) {
386 frame_size += sizeof(_sigregs_ext);
389 frame = get_sigframe(&ksig->ka, regs, frame_size);
390 if (frame == (void __user *) -1UL)
393 /* Set up backchain. */
394 if (__put_user(regs->gprs[15], (addr_t __user *) frame))
397 /* Set up to return from userspace. If provided, use a stub
398 already in userspace. */
399 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
400 restorer = (unsigned long) ksig->ka.sa.sa_restorer;
402 __u16 __user *svc = &frame->svc_insn;
403 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, svc))
405 restorer = (unsigned long) svc;
408 /* Create siginfo on the signal stack */
409 if (copy_siginfo_to_user(&frame->info, &ksig->info))
412 /* Store registers needed to create the signal frame */
415 /* Create ucontext on the signal stack. */
416 if (__put_user(uc_flags, &frame->uc.uc_flags) ||
417 __put_user(NULL, &frame->uc.uc_link) ||
418 __save_altstack(&frame->uc.uc_stack, regs->gprs[15]) ||
419 save_sigregs(regs, &frame->uc.uc_mcontext) ||
420 __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)) ||
421 save_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
424 /* Set up registers for signal handler */
425 regs->gprs[14] = restorer;
426 regs->gprs[15] = (unsigned long) frame;
427 /* Force default amode and default user address space control. */
428 regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
429 (PSW_USER_BITS & PSW_MASK_ASC) |
430 (regs->psw.mask & ~PSW_MASK_ASC);
431 regs->psw.addr = (unsigned long) ksig->ka.sa.sa_handler;
433 regs->gprs[2] = ksig->sig;
434 regs->gprs[3] = (unsigned long) &frame->info;
435 regs->gprs[4] = (unsigned long) &frame->uc;
436 regs->gprs[5] = current->thread.last_break;
440 static void handle_signal(struct ksignal *ksig, sigset_t *oldset,
441 struct pt_regs *regs)
445 /* Set up the stack frame */
446 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
447 ret = setup_rt_frame(ksig, oldset, regs);
449 ret = setup_frame(ksig->sig, &ksig->ka, oldset, regs);
451 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP));
455 * Note that 'init' is a special process: it doesn't get signals it doesn't
456 * want to handle. Thus you cannot kill init even with a SIGKILL even by
459 * Note that we go through the signals twice: once to check the signals that
460 * the kernel can handle, and then we build all the user-level signal handling
461 * stack-frames in one go after that.
464 void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal)
467 sigset_t *oldset = sigmask_to_save();
470 * Get signal to deliver. When running under ptrace, at this point
471 * the debugger may change all our registers, including the system
474 current->thread.system_call =
475 test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;
477 if (has_signal && get_signal(&ksig)) {
478 /* Whee! Actually deliver the signal. */
479 if (current->thread.system_call) {
480 regs->int_code = current->thread.system_call;
481 /* Check for system call restarting. */
482 switch (regs->gprs[2]) {
483 case -ERESTART_RESTARTBLOCK:
484 case -ERESTARTNOHAND:
485 regs->gprs[2] = -EINTR;
488 if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
489 regs->gprs[2] = -EINTR;
493 case -ERESTARTNOINTR:
494 regs->gprs[2] = regs->orig_gpr2;
496 __rewind_psw(regs->psw,
497 regs->int_code >> 16);
501 /* No longer in a system call */
502 clear_pt_regs_flag(regs, PIF_SYSCALL);
503 clear_pt_regs_flag(regs, PIF_SYSCALL_RESTART);
504 rseq_signal_deliver(&ksig, regs);
505 if (is_compat_task())
506 handle_signal32(&ksig, oldset, regs);
508 handle_signal(&ksig, oldset, regs);
512 /* No handlers present - check for system call restart */
513 clear_pt_regs_flag(regs, PIF_SYSCALL);
514 clear_pt_regs_flag(regs, PIF_SYSCALL_RESTART);
515 if (current->thread.system_call) {
516 regs->int_code = current->thread.system_call;
517 switch (regs->gprs[2]) {
518 case -ERESTART_RESTARTBLOCK:
519 /* Restart with sys_restart_syscall */
520 regs->int_code = __NR_restart_syscall;
522 case -ERESTARTNOHAND:
524 case -ERESTARTNOINTR:
525 /* Restart system call with magic TIF bit. */
526 regs->gprs[2] = regs->orig_gpr2;
527 set_pt_regs_flag(regs, PIF_SYSCALL_RESTART);
528 if (test_thread_flag(TIF_SINGLE_STEP))
529 clear_thread_flag(TIF_PER_TRAP);
535 * If there's no signal to deliver, we just put the saved sigmask back.
537 restore_saved_sigmask();
540 void do_notify_resume(struct pt_regs *regs)
542 tracehook_notify_resume(regs);
543 rseq_handle_notify_resume(NULL, regs);