arch/s390/kernel/signal.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  *    Copyright IBM Corp. 1999, 2006
  *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
  *
  *    Based on Intel version
  *
  *  Copyright (C) 1991, 1992  Linus Torvalds
  *
  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
  */

 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
 #include <linux/kernel.h>
 #include <linux/signal.h>
 #include <linux/entry-common.h>
 #include <linux/errno.h>
 #include <linux/wait.h>
 #include <linux/ptrace.h>
 #include <linux/unistd.h>
 #include <linux/stddef.h>
 #include <linux/tty.h>
 #include <linux/personality.h>
 #include <linux/binfmts.h>
 #include <linux/syscalls.h>
 #include <linux/compat.h>
 #include <asm/ucontext.h>
 #include <linux/uaccess.h>
 #include <asm/lowcore.h>
 #include <asm/switch_to.h>
 #include <asm/vdso.h>
 #include "entry.h"

 /*
  * Layout of an old-style signal-frame:
  *	-----------------------------------------
  *	| save area (_SIGNAL_FRAMESIZE)		|
  *	-----------------------------------------
  *	| struct sigcontext			|
  *	|	oldmask				|
  *	|	_sigregs *			|
  *	-----------------------------------------
  *	| _sigregs with				|
  *	|	_s390_regs_common		|
  *	|	_s390_fp_regs			|
  *	-----------------------------------------
  *	| int signo				|
  *	-----------------------------------------
  *	| _sigregs_ext with			|
  *	|	gprs_high 64 byte (opt)		|
  *	|	vxrs_low 128 byte (opt)		|
  *	|	vxrs_high 256 byte (opt)	|
  *	|	reserved 128 byte (opt)		|
  *	-----------------------------------------
  *	| __u16 svc_insn			|
  *	-----------------------------------------
  * The svc_insn entry with the sigreturn system call opcode does not
  * have a fixed position and moves if gprs_high or vxrs exist.
  * Future extensions will be added to _sigregs_ext.
  */
 struct sigframe
 {
 	__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
 	struct sigcontext sc;
 	_sigregs sregs;
 	int signo;
 	_sigregs_ext sregs_ext;
 	__u16 svc_insn;		/* Offset of svc_insn is NOT fixed! */
 };

 /*
  * Layout of an rt signal-frame:
  *	-----------------------------------------
  *	| save area (_SIGNAL_FRAMESIZE)		|
  *	-----------------------------------------
  *	| svc __NR_rt_sigreturn 2 byte		|
  *	-----------------------------------------
  *	| struct siginfo			|
  *	-----------------------------------------
  *	| struct ucontext_extended with		|
  *	|	unsigned long uc_flags		|
  *	|	struct ucontext *uc_link	|
  *	|	stack_t uc_stack		|
  *	|	_sigregs uc_mcontext with	|
  *	|		_s390_regs_common	|
  *	|		_s390_fp_regs		|
  *	|	sigset_t uc_sigmask		|
  *	|	_sigregs_ext uc_mcontext_ext	|
  *	|		gprs_high 64 byte (opt)	|
  *	|		vxrs_low 128 byte (opt)	|
  *	|		vxrs_high 256 byte (opt)|
  *	|		reserved 128 byte (opt)	|
  *	-----------------------------------------
  * Future extensions will be added to _sigregs_ext.
  */
 struct rt_sigframe
 {
 	__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
 	__u16 svc_insn;
 	struct siginfo info;
 	struct ucontext_extended uc;
 };

 /* Store registers needed to create the signal frame */
 static void store_sigregs(void)
 {
 	save_access_regs(current->thread.acrs);
 	save_fpu_regs();
 }

 /* Load registers after signal return */
 static void load_sigregs(void)
 {
 	restore_access_regs(current->thread.acrs);
 }

 /* Returns non-zero on fault. */
 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 {
 	_sigregs user_sregs;

 	/* Copy a 'clean' PSW mask to the user to avoid leaking
 	   information about whether PER is currently on.  */
 	user_sregs.regs.psw.mask = PSW_USER_BITS |
 		(regs->psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
 	user_sregs.regs.psw.addr = regs->psw.addr;
 	memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
 	memcpy(&user_sregs.regs.acrs, current->thread.acrs,
 	       sizeof(user_sregs.regs.acrs));
 	fpregs_store(&user_sregs.fpregs, &current->thread.fpu);
 	if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs)))
 		return -EFAULT;
 	return 0;
 }

 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 {
 	_sigregs user_sregs;

 	/* Always make any pending restarted system call return -EINTR */
 	current->restart_block.fn = do_no_restart_syscall;

 	if (__copy_from_user(&user_sregs, sregs, sizeof(user_sregs)))
 		return -EFAULT;

 	if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI))
 		return -EINVAL;

 	/* Test the floating-point-control word. */
 	if (test_fp_ctl(user_sregs.fpregs.fpc))
 		return -EINVAL;

 	/* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
 	regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) |
 		(user_sregs.regs.psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
 	/* Check for invalid user address space control. */
 	if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
 		regs->psw.mask = PSW_ASC_PRIMARY |
 			(regs->psw.mask & ~PSW_MASK_ASC);
 	/* Check for invalid amode */
 	if (regs->psw.mask & PSW_MASK_EA)
 		regs->psw.mask |= PSW_MASK_BA;
 	regs->psw.addr = user_sregs.regs.psw.addr;
 	memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
 	memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 	       sizeof(current->thread.acrs));

 	fpregs_load(&user_sregs.fpregs, &current->thread.fpu);

 	clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
 	return 0;
 }

 /* Returns non-zero on fault. */
 static int save_sigregs_ext(struct pt_regs *regs,
 			    _sigregs_ext __user *sregs_ext)
 {
 	__u64 vxrs[__NUM_VXRS_LOW];
 	int i;

 	/* Save vector registers to signal stack */
 	if (MACHINE_HAS_VX) {
 		for (i = 0; i < __NUM_VXRS_LOW; i++)
 			vxrs[i] = current->thread.fpu.vxrs[i].low;
 		if (__copy_to_user(&sregs_ext->vxrs_low, vxrs,
 				   sizeof(sregs_ext->vxrs_low)) ||
 		    __copy_to_user(&sregs_ext->vxrs_high,
 				   current->thread.fpu.vxrs + __NUM_VXRS_LOW,
 				   sizeof(sregs_ext->vxrs_high)))
 			return -EFAULT;
 	}
 	return 0;
 }

 static int restore_sigregs_ext(struct pt_regs *regs,
 			       _sigregs_ext __user *sregs_ext)
 {
 	__u64 vxrs[__NUM_VXRS_LOW];
 	int i;

 	/* Restore vector registers from signal stack */
 	if (MACHINE_HAS_VX) {
 		if (__copy_from_user(vxrs, &sregs_ext->vxrs_low,
 				     sizeof(sregs_ext->vxrs_low)) ||
 		    __copy_from_user(current->thread.fpu.vxrs + __NUM_VXRS_LOW,
 				     &sregs_ext->vxrs_high,
 				     sizeof(sregs_ext->vxrs_high)))
 			return -EFAULT;
 		for (i = 0; i < __NUM_VXRS_LOW; i++)
 			current->thread.fpu.vxrs[i].low = vxrs[i];
 	}
 	return 0;
 }

 SYSCALL_DEFINE0(sigreturn)
 {
 	struct pt_regs *regs = task_pt_regs(current);
 	struct sigframe __user *frame =
 		(struct sigframe __user *) regs->gprs[15];
 	sigset_t set;

 	if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 		goto badframe;
 	set_current_blocked(&set);
 	save_fpu_regs();
 	if (restore_sigregs(regs, &frame->sregs))
 		goto badframe;
 	if (restore_sigregs_ext(regs, &frame->sregs_ext))
 		goto badframe;
 	load_sigregs();
 	return regs->gprs[2];
 badframe:
 	force_sig(SIGSEGV);
 	return 0;
 }

 SYSCALL_DEFINE0(rt_sigreturn)
 {
 	struct pt_regs *regs = task_pt_regs(current);
 	struct rt_sigframe __user *frame =
 		(struct rt_sigframe __user *)regs->gprs[15];
 	sigset_t set;

 	if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 		goto badframe;
 	set_current_blocked(&set);
 	if (restore_altstack(&frame->uc.uc_stack))
 		goto badframe;
 	save_fpu_regs();
 	if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 		goto badframe;
 	if (restore_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
 		goto badframe;
 	load_sigregs();
 	return regs->gprs[2];
 badframe:
 	force_sig(SIGSEGV);
 	return 0;
 }

 /*
  * Determine which stack to use..
  */
 static inline void __user *
 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 {
 	unsigned long sp;

 	/* Default to using normal stack */
 	sp = regs->gprs[15];

 	/* Overflow on alternate signal stack gives SIGSEGV. */
 	if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 		return (void __user *) -1UL;

 	/* This is the X/Open sanctioned signal stack switching.  */
 	if (ka->sa.sa_flags & SA_ONSTACK) {
 		if (! sas_ss_flags(sp))
 			sp = current->sas_ss_sp + current->sas_ss_size;
 	}

 	return (void __user *)((sp - frame_size) & -8ul);
 }

 static int setup_frame(int sig, struct k_sigaction *ka,
 		       sigset_t *set, struct pt_regs * regs)
 {
 	struct sigframe __user *frame;
 	struct sigcontext sc;
 	unsigned long restorer;
 	size_t frame_size;

 	/*
 	 * gprs_high are only present for a 31-bit task running on
 	 * a 64-bit kernel (see compat_signal.c) but the space for
 	 * gprs_high need to be allocated if vector registers are
 	 * included in the signal frame on a 31-bit system.
 	 */
 	frame_size = sizeof(*frame) - sizeof(frame->sregs_ext);
 	if (MACHINE_HAS_VX)
 		frame_size += sizeof(frame->sregs_ext);
 	frame = get_sigframe(ka, regs, frame_size);
 	if (frame == (void __user *) -1UL)
 		return -EFAULT;

 	/* Set up backchain. */
 	if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 		return -EFAULT;

 	/* Create struct sigcontext on the signal stack */
 	memcpy(&sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE);
 	sc.sregs = (_sigregs __user __force *) &frame->sregs;
 	if (__copy_to_user(&frame->sc, &sc, sizeof(frame->sc)))
 		return -EFAULT;

 	/* Store registers needed to create the signal frame */
 	store_sigregs();

 	/* Create _sigregs on the signal stack */
 	if (save_sigregs(regs, &frame->sregs))
 		return -EFAULT;

 	/* Place signal number on stack to allow backtrace from handler.  */
 	if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 		return -EFAULT;

 	/* Create _sigregs_ext on the signal stack */
 	if (save_sigregs_ext(regs, &frame->sregs_ext))
 		return -EFAULT;

 	/* Set up to return from userspace.  If provided, use a stub
 	   already in userspace.  */
 	if (ka->sa.sa_flags & SA_RESTORER)
 		restorer = (unsigned long) ka->sa.sa_restorer;
 	else
 		restorer = VDSO64_SYMBOL(current, sigreturn);

 	/* Set up registers for signal handler */
 	regs->gprs[14] = restorer;
 	regs->gprs[15] = (unsigned long) frame;
 	/* Force default amode and default user address space control. */
 	regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
 		(PSW_USER_BITS & PSW_MASK_ASC) |
 		(regs->psw.mask & ~PSW_MASK_ASC);
 	regs->psw.addr = (unsigned long) ka->sa.sa_handler;

 	regs->gprs[2] = sig;
 	regs->gprs[3] = (unsigned long) &frame->sc;

 	/* We forgot to include these in the sigcontext.
 	   To avoid breaking binary compatibility, they are passed as args. */
 	if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
 	    sig == SIGTRAP || sig == SIGFPE) {
 		/* set extra registers only for synchronous signals */
 		regs->gprs[4] = regs->int_code & 127;
 		regs->gprs[5] = regs->int_parm_long;
 		regs->gprs[6] = current->thread.last_break;
 	}
 	return 0;
 }

 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 			  struct pt_regs *regs)
 {
 	struct rt_sigframe __user *frame;
 	unsigned long uc_flags, restorer;
 	size_t frame_size;

 	frame_size = sizeof(struct rt_sigframe) - sizeof(_sigregs_ext);
 	/*
 	 * gprs_high are only present for a 31-bit task running on
 	 * a 64-bit kernel (see compat_signal.c) but the space for
 	 * gprs_high need to be allocated if vector registers are
 	 * included in the signal frame on a 31-bit system.
 	 */
 	uc_flags = 0;
 	if (MACHINE_HAS_VX) {
 		frame_size += sizeof(_sigregs_ext);
 		uc_flags |= UC_VXRS;
 	}
 	frame = get_sigframe(&ksig->ka, regs, frame_size);
 	if (frame == (void __user *) -1UL)
 		return -EFAULT;

 	/* Set up backchain. */
 	if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 		return -EFAULT;

 	/* Set up to return from userspace.  If provided, use a stub
 	   already in userspace.  */
 	if (ksig->ka.sa.sa_flags & SA_RESTORER)
 		restorer = (unsigned long) ksig->ka.sa.sa_restorer;
 	else
 		restorer = VDSO64_SYMBOL(current, rt_sigreturn);

 	/* Create siginfo on the signal stack */
 	if (copy_siginfo_to_user(&frame->info, &ksig->info))
 		return -EFAULT;

 	/* Store registers needed to create the signal frame */
 	store_sigregs();

 	/* Create ucontext on the signal stack. */
 	if (__put_user(uc_flags, &frame->uc.uc_flags) ||
 	    __put_user(NULL, &frame->uc.uc_link) ||
 	    __save_altstack(&frame->uc.uc_stack, regs->gprs[15]) ||
 	    save_sigregs(regs, &frame->uc.uc_mcontext) ||
 	    __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)) ||
 	    save_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
 		return -EFAULT;

 	/* Set up registers for signal handler */
 	regs->gprs[14] = restorer;
 	regs->gprs[15] = (unsigned long) frame;
 	/* Force default amode and default user address space control. */
 	regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
 		(PSW_USER_BITS & PSW_MASK_ASC) |
 		(regs->psw.mask & ~PSW_MASK_ASC);
 	regs->psw.addr = (unsigned long) ksig->ka.sa.sa_handler;

 	regs->gprs[2] = ksig->sig;
 	regs->gprs[3] = (unsigned long) &frame->info;
 	regs->gprs[4] = (unsigned long) &frame->uc;
 	regs->gprs[5] = current->thread.last_break;
 	return 0;
 }

 static void handle_signal(struct ksignal *ksig, sigset_t *oldset,
 			  struct pt_regs *regs)
 {
 	int ret;

 	/* Set up the stack frame */
 	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 		ret = setup_rt_frame(ksig, oldset, regs);
 	else
 		ret = setup_frame(ksig->sig, &ksig->ka, oldset, regs);

 	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP));
 }

 /*
  * Note that 'init' is a special process: it doesn't get signals it doesn't
  * want to handle. Thus you cannot kill init even with a SIGKILL even by
  * mistake.
  *
  * Note that we go through the signals twice: once to check the signals that
  * the kernel can handle, and then we build all the user-level signal handling
  * stack-frames in one go after that.
  */

 void arch_do_signal_or_restart(struct pt_regs *regs)
 {
 	struct ksignal ksig;
 	sigset_t *oldset = sigmask_to_save();

 	/*
 	 * Get signal to deliver. When running under ptrace, at this point
 	 * the debugger may change all our registers, including the system
 	 * call information.
 	 */
 	current->thread.system_call =
 		test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;

 	if (get_signal(&ksig)) {
 		/* Whee!  Actually deliver the signal.  */
 		if (current->thread.system_call) {
 			regs->int_code = current->thread.system_call;
 			/* Check for system call restarting. */
 			switch (regs->gprs[2]) {
 			case -ERESTART_RESTARTBLOCK:
 			case -ERESTARTNOHAND:
 				regs->gprs[2] = -EINTR;
 				break;
 			case -ERESTARTSYS:
 				if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
 					regs->gprs[2] = -EINTR;
 					break;
 				}
 				fallthrough;
 			case -ERESTARTNOINTR:
 				regs->gprs[2] = regs->orig_gpr2;
 				regs->psw.addr =
 					__rewind_psw(regs->psw,
 						     regs->int_code >> 16);
 				break;
 			}
 		}
 		/* No longer in a system call */
 		clear_pt_regs_flag(regs, PIF_SYSCALL);

 		rseq_signal_deliver(&ksig, regs);
 		if (is_compat_task())
 			handle_signal32(&ksig, oldset, regs);
 		else
 			handle_signal(&ksig, oldset, regs);
 		return;
 	}

 	/* No handlers present - check for system call restart */
 	clear_pt_regs_flag(regs, PIF_SYSCALL);
 	if (current->thread.system_call) {
 		regs->int_code = current->thread.system_call;
 		switch (regs->gprs[2]) {
 		case -ERESTART_RESTARTBLOCK:
 			/* Restart with sys_restart_syscall */
 			regs->gprs[2] = regs->orig_gpr2;
 			current->restart_block.arch_data = regs->psw.addr;
 			if (is_compat_task())
 				regs->psw.addr = VDSO32_SYMBOL(current, restart_syscall);
 			else
 				regs->psw.addr = VDSO64_SYMBOL(current, restart_syscall);
 			if (test_thread_flag(TIF_SINGLE_STEP))
 				clear_thread_flag(TIF_PER_TRAP);
 			break;
 		case -ERESTARTNOHAND:
 		case -ERESTARTSYS:
 		case -ERESTARTNOINTR:
 			regs->gprs[2] = regs->orig_gpr2;
 			regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
 			if (test_thread_flag(TIF_SINGLE_STEP))
 				clear_thread_flag(TIF_PER_TRAP);
 			break;
 		}
 	}

 	/*
 	 * If there's no signal to deliver, we just put the saved sigmask back.
 	 */
 	restore_saved_sigmask();
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright IBM Corp. 1999, 2006
	* Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
	*
	* Based on Intel version
	*
	* Copyright (C) 1991, 1992 Linus Torvalds
	*
	* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
	*/

	#include <linux/sched.h>
	#include <linux/sched/task_stack.h>
	#include <linux/mm.h>
	#include <linux/smp.h>
	#include <linux/kernel.h>
	#include <linux/signal.h>
	#include <linux/entry-common.h>
	#include <linux/errno.h>
	#include <linux/wait.h>
	#include <linux/ptrace.h>
	#include <linux/unistd.h>
	#include <linux/stddef.h>
	#include <linux/tty.h>
	#include <linux/personality.h>
	#include <linux/binfmts.h>
	#include <linux/syscalls.h>
	#include <linux/compat.h>
	#include <asm/ucontext.h>
	#include <linux/uaccess.h>
	#include <asm/lowcore.h>
	#include <asm/switch_to.h>
	#include <asm/vdso.h>
	#include "entry.h"

	/*
	* Layout of an old-style signal-frame:
	* -----------------------------------------
	* \| save area (_SIGNAL_FRAMESIZE) \|
	* -----------------------------------------
	* \| struct sigcontext \|
	* \| oldmask \|
	* \| _sigregs * \|
	* -----------------------------------------
	* \| _sigregs with \|
	* \| _s390_regs_common \|
	* \| _s390_fp_regs \|
	* -----------------------------------------
	* \| int signo \|
	* -----------------------------------------
	* \| _sigregs_ext with \|
	* \| gprs_high 64 byte (opt) \|
	* \| vxrs_low 128 byte (opt) \|
	* \| vxrs_high 256 byte (opt) \|
	* \| reserved 128 byte (opt) \|
	* -----------------------------------------
	* \| __u16 svc_insn \|
	* -----------------------------------------
	* The svc_insn entry with the sigreturn system call opcode does not
	* have a fixed position and moves if gprs_high or vxrs exist.
	* Future extensions will be added to _sigregs_ext.
	*/
	struct sigframe
	{
	__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
	struct sigcontext sc;
	_sigregs sregs;
	int signo;
	_sigregs_ext sregs_ext;
	__u16 svc_insn; /* Offset of svc_insn is NOT fixed! */
	};

	/*
	* Layout of an rt signal-frame:
	* -----------------------------------------
	* \| save area (_SIGNAL_FRAMESIZE) \|
	* -----------------------------------------
	* \| svc __NR_rt_sigreturn 2 byte \|
	* -----------------------------------------
	* \| struct siginfo \|
	* -----------------------------------------
	* \| struct ucontext_extended with \|
	* \| unsigned long uc_flags \|
	* \| struct ucontext *uc_link \|
	* \| stack_t uc_stack \|
	* \| _sigregs uc_mcontext with \|
	* \| _s390_regs_common \|
	* \| _s390_fp_regs \|
	* \| sigset_t uc_sigmask \|
	* \| _sigregs_ext uc_mcontext_ext \|
	* \| gprs_high 64 byte (opt) \|
	* \| vxrs_low 128 byte (opt) \|
	* \| vxrs_high 256 byte (opt)\|
	* \| reserved 128 byte (opt) \|
	* -----------------------------------------
	* Future extensions will be added to _sigregs_ext.
	*/
	struct rt_sigframe
	{
	__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
	__u16 svc_insn;
	struct siginfo info;
	struct ucontext_extended uc;
	};

	/* Store registers needed to create the signal frame */
	static void store_sigregs(void)
	{
	save_access_regs(current->thread.acrs);
	save_fpu_regs();
	}

	/* Load registers after signal return */
	static void load_sigregs(void)
	{
	restore_access_regs(current->thread.acrs);
	}

	/* Returns non-zero on fault. */
	static int save_sigregs(struct pt_regs regs, _sigregs __user sregs)
	{
	_sigregs user_sregs;

	/* Copy a 'clean' PSW mask to the user to avoid leaking
	information about whether PER is currently on. */
	user_sregs.regs.psw.mask = PSW_USER_BITS \|
	(regs->psw.mask & (PSW_MASK_USER \| PSW_MASK_RI));
	user_sregs.regs.psw.addr = regs->psw.addr;
	memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
	memcpy(&user_sregs.regs.acrs, current->thread.acrs,
	sizeof(user_sregs.regs.acrs));
	fpregs_store(&user_sregs.fpregs, &current->thread.fpu);
	if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs)))
	return -EFAULT;
	return 0;
	}

	static int restore_sigregs(struct pt_regs regs, _sigregs __user sregs)
	{
	_sigregs user_sregs;

	/* Always make any pending restarted system call return -EINTR */
	current->restart_block.fn = do_no_restart_syscall;

	if (__copy_from_user(&user_sregs, sregs, sizeof(user_sregs)))
	return -EFAULT;

	if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI))
	return -EINVAL;

	/* Test the floating-point-control word. */
	if (test_fp_ctl(user_sregs.fpregs.fpc))
	return -EINVAL;

	/* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
	regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER \| PSW_MASK_RI)) \|
	(user_sregs.regs.psw.mask & (PSW_MASK_USER \| PSW_MASK_RI));
	/* Check for invalid user address space control. */
	if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
	regs->psw.mask = PSW_ASC_PRIMARY \|
	(regs->psw.mask & ~PSW_MASK_ASC);
	/* Check for invalid amode */
	if (regs->psw.mask & PSW_MASK_EA)
	regs->psw.mask \|= PSW_MASK_BA;
	regs->psw.addr = user_sregs.regs.psw.addr;
	memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
	memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
	sizeof(current->thread.acrs));

	fpregs_load(&user_sregs.fpregs, &current->thread.fpu);

	clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
	return 0;
	}

	/* Returns non-zero on fault. */
	static int save_sigregs_ext(struct pt_regs *regs,
	_sigregs_ext __user *sregs_ext)
	{
	__u64 vxrs[__NUM_VXRS_LOW];
	int i;

	/* Save vector registers to signal stack */
	if (MACHINE_HAS_VX) {
	for (i = 0; i < __NUM_VXRS_LOW; i++)
	vxrs[i] = current->thread.fpu.vxrs[i].low;
	if (__copy_to_user(&sregs_ext->vxrs_low, vxrs,
	sizeof(sregs_ext->vxrs_low)) \|\|
	__copy_to_user(&sregs_ext->vxrs_high,
	current->thread.fpu.vxrs + __NUM_VXRS_LOW,
	sizeof(sregs_ext->vxrs_high)))
	return -EFAULT;
	}
	return 0;
	}

	static int restore_sigregs_ext(struct pt_regs *regs,
	_sigregs_ext __user *sregs_ext)
	{
	__u64 vxrs[__NUM_VXRS_LOW];
	int i;

	/* Restore vector registers from signal stack */
	if (MACHINE_HAS_VX) {
	if (__copy_from_user(vxrs, &sregs_ext->vxrs_low,
	sizeof(sregs_ext->vxrs_low)) \|\|
	__copy_from_user(current->thread.fpu.vxrs + __NUM_VXRS_LOW,
	&sregs_ext->vxrs_high,
	sizeof(sregs_ext->vxrs_high)))
	return -EFAULT;
	for (i = 0; i < __NUM_VXRS_LOW; i++)
	current->thread.fpu.vxrs[i].low = vxrs[i];
	}
	return 0;
	}

	SYSCALL_DEFINE0(sigreturn)
	{
	struct pt_regs *regs = task_pt_regs(current);
	struct sigframe __user *frame =
	(struct sigframe __user *) regs->gprs[15];
	sigset_t set;

	if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
	goto badframe;
	set_current_blocked(&set);
	save_fpu_regs();
	if (restore_sigregs(regs, &frame->sregs))
	goto badframe;
	if (restore_sigregs_ext(regs, &frame->sregs_ext))
	goto badframe;
	load_sigregs();
	return regs->gprs[2];
	badframe:
	force_sig(SIGSEGV);
	return 0;
	}

	SYSCALL_DEFINE0(rt_sigreturn)
	{
	struct pt_regs *regs = task_pt_regs(current);
	struct rt_sigframe __user *frame =
	(struct rt_sigframe __user *)regs->gprs[15];
	sigset_t set;

	if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
	goto badframe;
	set_current_blocked(&set);
	if (restore_altstack(&frame->uc.uc_stack))
	goto badframe;
	save_fpu_regs();
	if (restore_sigregs(regs, &frame->uc.uc_mcontext))
	goto badframe;
	if (restore_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
	goto badframe;
	load_sigregs();
	return regs->gprs[2];
	badframe:
	force_sig(SIGSEGV);
	return 0;
	}

	/*
	* Determine which stack to use..
	*/
	static inline void __user *
	get_sigframe(struct k_sigaction ka, struct pt_regs regs, size_t frame_size)
	{
	unsigned long sp;

	/* Default to using normal stack */
	sp = regs->gprs[15];

	/* Overflow on alternate signal stack gives SIGSEGV. */
	if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
	return (void __user *) -1UL;

	/* This is the X/Open sanctioned signal stack switching. */
	if (ka->sa.sa_flags & SA_ONSTACK) {
	if (! sas_ss_flags(sp))
	sp = current->sas_ss_sp + current->sas_ss_size;
	}

	return (void __user *)((sp - frame_size) & -8ul);
	}

	static int setup_frame(int sig, struct k_sigaction *ka,
	sigset_t set, struct pt_regs regs)
	{
	struct sigframe __user *frame;
	struct sigcontext sc;
	unsigned long restorer;
	size_t frame_size;

	/*
	* gprs_high are only present for a 31-bit task running on
	* a 64-bit kernel (see compat_signal.c) but the space for
	* gprs_high need to be allocated if vector registers are
	* included in the signal frame on a 31-bit system.
	*/
	frame_size = sizeof(*frame) - sizeof(frame->sregs_ext);
	if (MACHINE_HAS_VX)
	frame_size += sizeof(frame->sregs_ext);
	frame = get_sigframe(ka, regs, frame_size);
	if (frame == (void __user *) -1UL)
	return -EFAULT;

	/* Set up backchain. */
	if (__put_user(regs->gprs[15], (addr_t __user *) frame))
	return -EFAULT;

	/* Create struct sigcontext on the signal stack */
	memcpy(&sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE);
	sc.sregs = (_sigregs __user __force *) &frame->sregs;
	if (__copy_to_user(&frame->sc, &sc, sizeof(frame->sc)))
	return -EFAULT;

	/* Store registers needed to create the signal frame */
	store_sigregs();

	/* Create _sigregs on the signal stack */
	if (save_sigregs(regs, &frame->sregs))
	return -EFAULT;

	/* Place signal number on stack to allow backtrace from handler. */
	if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
	return -EFAULT;

	/* Create _sigregs_ext on the signal stack */
	if (save_sigregs_ext(regs, &frame->sregs_ext))
	return -EFAULT;

	/* Set up to return from userspace. If provided, use a stub
	already in userspace. */
	if (ka->sa.sa_flags & SA_RESTORER)
	restorer = (unsigned long) ka->sa.sa_restorer;
	else
	restorer = VDSO64_SYMBOL(current, sigreturn);

	/* Set up registers for signal handler */
	regs->gprs[14] = restorer;
	regs->gprs[15] = (unsigned long) frame;
	/* Force default amode and default user address space control. */
	regs->psw.mask = PSW_MASK_EA \| PSW_MASK_BA \|
	(PSW_USER_BITS & PSW_MASK_ASC) \|
	(regs->psw.mask & ~PSW_MASK_ASC);
	regs->psw.addr = (unsigned long) ka->sa.sa_handler;

	regs->gprs[2] = sig;
	regs->gprs[3] = (unsigned long) &frame->sc;

	/* We forgot to include these in the sigcontext.
	To avoid breaking binary compatibility, they are passed as args. */
	if (sig == SIGSEGV \|\| sig == SIGBUS \|\| sig == SIGILL \|\|
	sig == SIGTRAP \|\| sig == SIGFPE) {
	/* set extra registers only for synchronous signals */
	regs->gprs[4] = regs->int_code & 127;
	regs->gprs[5] = regs->int_parm_long;
	regs->gprs[6] = current->thread.last_break;
	}
	return 0;
	}

	static int setup_rt_frame(struct ksignal ksig, sigset_t set,
	struct pt_regs *regs)
	{
	struct rt_sigframe __user *frame;
	unsigned long uc_flags, restorer;
	size_t frame_size;

	frame_size = sizeof(struct rt_sigframe) - sizeof(_sigregs_ext);
	/*
	* gprs_high are only present for a 31-bit task running on
	* a 64-bit kernel (see compat_signal.c) but the space for
	* gprs_high need to be allocated if vector registers are
	* included in the signal frame on a 31-bit system.
	*/
	uc_flags = 0;
	if (MACHINE_HAS_VX) {
	frame_size += sizeof(_sigregs_ext);
	uc_flags \|= UC_VXRS;
	}
	frame = get_sigframe(&ksig->ka, regs, frame_size);
	if (frame == (void __user *) -1UL)
	return -EFAULT;

	/* Set up backchain. */
	if (__put_user(regs->gprs[15], (addr_t __user *) frame))
	return -EFAULT;

	/* Set up to return from userspace. If provided, use a stub
	already in userspace. */
	if (ksig->ka.sa.sa_flags & SA_RESTORER)
	restorer = (unsigned long) ksig->ka.sa.sa_restorer;
	else
	restorer = VDSO64_SYMBOL(current, rt_sigreturn);

	/* Create siginfo on the signal stack */
	if (copy_siginfo_to_user(&frame->info, &ksig->info))
	return -EFAULT;

	/* Store registers needed to create the signal frame */
	store_sigregs();

	/* Create ucontext on the signal stack. */
	if (__put_user(uc_flags, &frame->uc.uc_flags) \|\|
	__put_user(NULL, &frame->uc.uc_link) \|\|
	__save_altstack(&frame->uc.uc_stack, regs->gprs[15]) \|\|
	save_sigregs(regs, &frame->uc.uc_mcontext) \|\|
	__copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)) \|\|
	save_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
	return -EFAULT;

	/* Set up registers for signal handler */
	regs->gprs[14] = restorer;
	regs->gprs[15] = (unsigned long) frame;
	/* Force default amode and default user address space control. */
	regs->psw.mask = PSW_MASK_EA \| PSW_MASK_BA \|
	(PSW_USER_BITS & PSW_MASK_ASC) \|
	(regs->psw.mask & ~PSW_MASK_ASC);
	regs->psw.addr = (unsigned long) ksig->ka.sa.sa_handler;

	regs->gprs[2] = ksig->sig;
	regs->gprs[3] = (unsigned long) &frame->info;
	regs->gprs[4] = (unsigned long) &frame->uc;
	regs->gprs[5] = current->thread.last_break;
	return 0;
	}

	static void handle_signal(struct ksignal ksig, sigset_t oldset,
	struct pt_regs *regs)
	{
	int ret;

	/* Set up the stack frame */
	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
	ret = setup_rt_frame(ksig, oldset, regs);
	else
	ret = setup_frame(ksig->sig, &ksig->ka, oldset, regs);

	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP));
	}

	/*
	* Note that 'init' is a special process: it doesn't get signals it doesn't
	* want to handle. Thus you cannot kill init even with a SIGKILL even by
	* mistake.
	*
	* Note that we go through the signals twice: once to check the signals that
	* the kernel can handle, and then we build all the user-level signal handling
	* stack-frames in one go after that.
	*/

	void arch_do_signal_or_restart(struct pt_regs *regs)
	{
	struct ksignal ksig;
	sigset_t *oldset = sigmask_to_save();

	/*
	* Get signal to deliver. When running under ptrace, at this point
	* the debugger may change all our registers, including the system
	* call information.
	*/
	current->thread.system_call =
	test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;

	if (get_signal(&ksig)) {
	/* Whee! Actually deliver the signal. */
	if (current->thread.system_call) {
	regs->int_code = current->thread.system_call;
	/* Check for system call restarting. */
	switch (regs->gprs[2]) {
	case -ERESTART_RESTARTBLOCK:
	case -ERESTARTNOHAND:
	regs->gprs[2] = -EINTR;
	break;
	case -ERESTARTSYS:
	if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
	regs->gprs[2] = -EINTR;
	break;
	}
	fallthrough;
	case -ERESTARTNOINTR:
	regs->gprs[2] = regs->orig_gpr2;
	regs->psw.addr =
	__rewind_psw(regs->psw,
	regs->int_code >> 16);
	break;
	}
	}
	/* No longer in a system call */
	clear_pt_regs_flag(regs, PIF_SYSCALL);

	rseq_signal_deliver(&ksig, regs);
	if (is_compat_task())
	handle_signal32(&ksig, oldset, regs);
	else
	handle_signal(&ksig, oldset, regs);
	return;
	}

	/* No handlers present - check for system call restart */
	clear_pt_regs_flag(regs, PIF_SYSCALL);
	if (current->thread.system_call) {
	regs->int_code = current->thread.system_call;
	switch (regs->gprs[2]) {
	case -ERESTART_RESTARTBLOCK:
	/* Restart with sys_restart_syscall */
	regs->gprs[2] = regs->orig_gpr2;
	current->restart_block.arch_data = regs->psw.addr;
	if (is_compat_task())
	regs->psw.addr = VDSO32_SYMBOL(current, restart_syscall);
	else
	regs->psw.addr = VDSO64_SYMBOL(current, restart_syscall);
	if (test_thread_flag(TIF_SINGLE_STEP))
	clear_thread_flag(TIF_PER_TRAP);
	break;
	case -ERESTARTNOHAND:
	case -ERESTARTSYS:
	case -ERESTARTNOINTR:
	regs->gprs[2] = regs->orig_gpr2;
	regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
	if (test_thread_flag(TIF_SINGLE_STEP))
	clear_thread_flag(TIF_PER_TRAP);
	break;
	}
	}

	/*
	* If there's no signal to deliver, we just put the saved sigmask back.
	*/
	restore_saved_sigmask();
	}