s390/kernel/ptrace.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  Ptrace user space interface.
 *
 *    Copyright IBM Corp. 1999, 2010
 *    Author(s): Denis Joseph Barrow
 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/cpufeature.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/audit.h>
#include <linux/signal.h>
#include <linux/elf.h>
#include <linux/regset.h>
#include <linux/seccomp.h>
#include <trace/syscall.h>
#include <asm/guarded_storage.h>
#include <asm/access-regs.h>
#include <asm/page.h>
#include <linux/uaccess.h>
#include <asm/unistd.h>
#include <asm/runtime_instr.h>
#include <asm/facility.h>
#include <asm/machine.h>
#include <asm/ptrace.h>
#include <asm/rwonce.h>
#include <asm/fpu.h>

#include "entry.h"

void update_cr_regs(struct task_struct *task)
{
	struct pt_regs *regs = task_pt_regs(task);
	struct thread_struct *thread = &task->thread;
	union ctlreg0 cr0_old, cr0_new;
	union ctlreg2 cr2_old, cr2_new;
	int cr0_changed, cr2_changed;
	union {
		struct ctlreg regs[3];
		struct {
			struct ctlreg control;
			struct ctlreg start;
			struct ctlreg end;
		};
	} old, new;

	local_ctl_store(0, &cr0_old.reg);
	local_ctl_store(2, &cr2_old.reg);
	cr0_new = cr0_old;
	cr2_new = cr2_old;
	/* Take care of the enable/disable of transactional execution. */
	if (machine_has_tx()) {
		/* Set or clear transaction execution TXC bit 8. */
		cr0_new.tcx = 1;
		if (task->thread.per_flags & PER_FLAG_NO_TE)
			cr0_new.tcx = 0;
		/* Set or clear transaction execution TDC bits 62 and 63. */
		cr2_new.tdc = 0;
		if (task->thread.per_flags & PER_FLAG_TE_ABORT_RAND) {
			if (task->thread.per_flags & PER_FLAG_TE_ABORT_RAND_TEND)
				cr2_new.tdc = 1;
			else
				cr2_new.tdc = 2;
		}
	}
	/* Take care of enable/disable of guarded storage. */
	if (cpu_has_gs()) {
		cr2_new.gse = 0;
		if (task->thread.gs_cb)
			cr2_new.gse = 1;
	}
	/* Load control register 0/2 iff changed */
	cr0_changed = cr0_new.val != cr0_old.val;
	cr2_changed = cr2_new.val != cr2_old.val;
	if (cr0_changed)
		local_ctl_load(0, &cr0_new.reg);
	if (cr2_changed)
		local_ctl_load(2, &cr2_new.reg);
	/* Copy user specified PER registers */
	new.control.val = thread->per_user.control;
	new.start.val = thread->per_user.start;
	new.end.val = thread->per_user.end;

	/* merge TIF_SINGLE_STEP into user specified PER registers. */
	if (test_tsk_thread_flag(task, TIF_SINGLE_STEP) ||
	    test_tsk_thread_flag(task, TIF_UPROBE_SINGLESTEP)) {
		if (test_tsk_thread_flag(task, TIF_BLOCK_STEP))
			new.control.val |= PER_EVENT_BRANCH;
		else
			new.control.val |= PER_EVENT_IFETCH;
		new.control.val |= PER_CONTROL_SUSPENSION;
		new.control.val |= PER_EVENT_TRANSACTION_END;
		if (test_tsk_thread_flag(task, TIF_UPROBE_SINGLESTEP))
			new.control.val |= PER_EVENT_IFETCH;
		new.start.val = 0;
		new.end.val = -1UL;
	}

	/* Take care of the PER enablement bit in the PSW. */
	if (!(new.control.val & PER_EVENT_MASK)) {
		regs->psw.mask &= ~PSW_MASK_PER;
		return;
	}
	regs->psw.mask |= PSW_MASK_PER;
	__local_ctl_store(9, 11, old.regs);
	if (memcmp(&new, &old, sizeof(struct per_regs)) != 0)
		__local_ctl_load(9, 11, new.regs);
}

void user_enable_single_step(struct task_struct *task)
{
	clear_tsk_thread_flag(task, TIF_BLOCK_STEP);
	set_tsk_thread_flag(task, TIF_SINGLE_STEP);
}

void user_disable_single_step(struct task_struct *task)
{
	clear_tsk_thread_flag(task, TIF_BLOCK_STEP);
	clear_tsk_thread_flag(task, TIF_SINGLE_STEP);
}

void user_enable_block_step(struct task_struct *task)
{
	set_tsk_thread_flag(task, TIF_SINGLE_STEP);
	set_tsk_thread_flag(task, TIF_BLOCK_STEP);
}

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Clear all debugging related fields.
 */
void ptrace_disable(struct task_struct *task)
{
	memset(&task->thread.per_user, 0, sizeof(task->thread.per_user));
	memset(&task->thread.per_event, 0, sizeof(task->thread.per_event));
	clear_tsk_thread_flag(task, TIF_SINGLE_STEP);
	clear_tsk_thread_flag(task, TIF_PER_TRAP);
	task->thread.per_flags = 0;
}

#define __ADDR_MASK 7

static inline unsigned long __peek_user_per(struct task_struct *child,
					    addr_t addr)
{
	if (addr == offsetof(struct per_struct_kernel, cr9))
		/* Control bits of the active per set. */
		return test_thread_flag(TIF_SINGLE_STEP) ?
			PER_EVENT_IFETCH : child->thread.per_user.control;
	else if (addr == offsetof(struct per_struct_kernel, cr10))
		/* Start address of the active per set. */
		return test_thread_flag(TIF_SINGLE_STEP) ?
			0 : child->thread.per_user.start;
	else if (addr == offsetof(struct per_struct_kernel, cr11))
		/* End address of the active per set. */
		return test_thread_flag(TIF_SINGLE_STEP) ?
			-1UL : child->thread.per_user.end;
	else if (addr == offsetof(struct per_struct_kernel, bits))
		/* Single-step bit. */
		return test_thread_flag(TIF_SINGLE_STEP) ?
			(1UL << (BITS_PER_LONG - 1)) : 0;
	else if (addr == offsetof(struct per_struct_kernel, starting_addr))
		/* Start address of the user specified per set. */
		return child->thread.per_user.start;
	else if (addr == offsetof(struct per_struct_kernel, ending_addr))
		/* End address of the user specified per set. */
		return child->thread.per_user.end;
	else if (addr == offsetof(struct per_struct_kernel, perc_atmid))
		/* PER code, ATMID and AI of the last PER trap */
		return (unsigned long)
			child->thread.per_event.cause << (BITS_PER_LONG - 16);
	else if (addr == offsetof(struct per_struct_kernel, address))
		/* Address of the last PER trap */
		return child->thread.per_event.address;
	else if (addr == offsetof(struct per_struct_kernel, access_id))
		/* Access id of the last PER trap */
		return (unsigned long)
			child->thread.per_event.paid << (BITS_PER_LONG - 8);
	return 0;
}

/*
 * Read the word at offset addr from the user area of a process. The
 * trouble here is that the information is littered over different
 * locations. The process registers are found on the kernel stack,
 * the floating point stuff and the trace settings are stored in
 * the task structure. In addition the different structures in
 * struct user contain pad bytes that should be read as zeroes.
 * Lovely...
 */
static unsigned long __peek_user(struct task_struct *child, addr_t addr)
{
	addr_t offset, tmp;

	if (addr < offsetof(struct user, regs.acrs)) {
		/*
		 * psw and gprs are stored on the stack
		 */
		tmp = *(addr_t *)((addr_t) &task_pt_regs(child)->psw + addr);
		if (addr == offsetof(struct user, regs.psw.mask)) {
			/* Return a clean psw mask. */
			tmp &= PSW_MASK_USER | PSW_MASK_RI;
			tmp |= PSW_USER_BITS;
		}

	} else if (addr < offsetof(struct user, regs.orig_gpr2)) {
		/*
		 * access registers are stored in the thread structure
		 */
		offset = addr - offsetof(struct user, regs.acrs);
		/*
		 * Very special case: old & broken 64 bit gdb reading
		 * from acrs[15]. Result is a 64 bit value. Read the
		 * 32 bit acrs[15] value and shift it by 32. Sick...
		 */
		if (addr == offsetof(struct user, regs.acrs[15]))
			tmp = ((unsigned long) child->thread.acrs[15]) << 32;
		else
			tmp = *(addr_t *)((addr_t) &child->thread.acrs + offset);

	} else if (addr == offsetof(struct user, regs.orig_gpr2)) {
		/*
		 * orig_gpr2 is stored on the kernel stack
		 */
		tmp = (addr_t) task_pt_regs(child)->orig_gpr2;

	} else if (addr < offsetof(struct user, regs.fp_regs)) {
		/*
		 * prevent reads of padding hole between
		 * orig_gpr2 and fp_regs on s390.
		 */
		tmp = 0;

	} else if (addr == offsetof(struct user, regs.fp_regs.fpc)) {
		/*
		 * floating point control reg. is in the thread structure
		 */
		tmp = child->thread.ufpu.fpc;
		tmp <<= BITS_PER_LONG - 32;

	} else if (addr < offsetof(struct user, regs.fp_regs) + sizeof(s390_fp_regs)) {
		/*
		 * floating point regs. are in the child->thread.ufpu.vxrs array
		 */
		offset = addr - offsetof(struct user, regs.fp_regs.fprs);
		tmp = *(addr_t *)((addr_t)child->thread.ufpu.vxrs + 2 * offset);
	} else if (addr < offsetof(struct user, regs.per_info) + sizeof(per_struct)) {
		/*
		 * Handle access to the per_info structure.
		 */
		addr -= offsetof(struct user, regs.per_info);
		tmp = __peek_user_per(child, addr);

	} else
		tmp = 0;

	return tmp;
}

static int
peek_user(struct task_struct *child, addr_t addr, addr_t data)
{
	addr_t tmp, mask;

	/*
	 * Stupid gdb peeks/pokes the access registers in 64 bit with
	 * an alignment of 4. Programmers from hell...
	 */
	mask = __ADDR_MASK;
	if (addr >= offsetof(struct user, regs.acrs) &&
	    addr < offsetof(struct user, regs.orig_gpr2))
		mask = 3;
	if ((addr & mask) || addr > sizeof(struct user) - __ADDR_MASK)
		return -EIO;

	tmp = __peek_user(child, addr);
	return put_user(tmp, (addr_t __user *) data);
}

static inline void __poke_user_per(struct task_struct *child,
				   addr_t addr, addr_t data)
{
	/*
	 * There are only three fields in the per_info struct that the
	 * debugger user can write to.
	 * 1) cr9: the debugger wants to set a new PER event mask
	 * 2) starting_addr: the debugger wants to set a new starting
	 *    address to use with the PER event mask.
	 * 3) ending_addr: the debugger wants to set a new ending
	 *    address to use with the PER event mask.
	 * The user specified PER event mask and the start and end
	 * addresses are used only if single stepping is not in effect.
	 * Writes to any other field in per_info are ignored.
	 */
	if (addr == offsetof(struct per_struct_kernel, cr9))
		/* PER event mask of the user specified per set. */
		child->thread.per_user.control =
			data & (PER_EVENT_MASK | PER_CONTROL_MASK);
	else if (addr == offsetof(struct per_struct_kernel, starting_addr))
		/* Starting address of the user specified per set. */
		child->thread.per_user.start = data;
	else if (addr == offsetof(struct per_struct_kernel, ending_addr))
		/* Ending address of the user specified per set. */
		child->thread.per_user.end = data;
}

/*
 * Write a word to the user area of a process at location addr. This
 * operation does have an additional problem compared to peek_user.
 * Stores to the program status word and on the floating point
 * control register needs to get checked for validity.
 */
static int __poke_user(struct task_struct *child, addr_t addr, addr_t data)
{
	addr_t offset;


	if (addr < offsetof(struct user, regs.acrs)) {
		struct pt_regs *regs = task_pt_regs(child);
		/*
		 * psw and gprs are stored on the stack
		 */
		if (addr == offsetof(struct user, regs.psw.mask)) {
			unsigned long mask = PSW_MASK_USER;

			mask |= is_ri_task(child) ? PSW_MASK_RI : 0;
			if ((data ^ PSW_USER_BITS) & ~mask)
				/* Invalid psw mask. */
				return -EINVAL;
			if ((data & PSW_MASK_ASC) == PSW_ASC_HOME)
				/* Invalid address-space-control bits */
				return -EINVAL;
			if ((data & PSW_MASK_EA) && !(data & PSW_MASK_BA))
				/* Invalid addressing mode bits */
				return -EINVAL;
		}

		if (test_pt_regs_flag(regs, PIF_SYSCALL) &&
			addr == offsetof(struct user, regs.gprs[2])) {
			struct pt_regs *regs = task_pt_regs(child);

			regs->int_code = 0x20000 | (data & 0xffff);
		}
		*(addr_t *)((addr_t) &regs->psw + addr) = data;
	} else if (addr < offsetof(struct user, regs.orig_gpr2)) {
		/*
		 * access registers are stored in the thread structure
		 */
		offset = addr - offsetof(struct user, regs.acrs);
		/*
		 * Very special case: old & broken 64 bit gdb writing
		 * to acrs[15] with a 64 bit value. Ignore the lower
		 * half of the value and write the upper 32 bit to
		 * acrs[15]. Sick...
		 */
		if (addr == offsetof(struct user, regs.acrs[15]))
			child->thread.acrs[15] = (unsigned int) (data >> 32);
		else
			*(addr_t *)((addr_t) &child->thread.acrs + offset) = data;

	} else if (addr == offsetof(struct user, regs.orig_gpr2)) {
		/*
		 * orig_gpr2 is stored on the kernel stack
		 */
		task_pt_regs(child)->orig_gpr2 = data;

	} else if (addr < offsetof(struct user, regs.fp_regs)) {
		/*
		 * prevent writes of padding hole between
		 * orig_gpr2 and fp_regs on s390.
		 */
		return 0;

	} else if (addr == offsetof(struct user, regs.fp_regs.fpc)) {
		/*
		 * floating point control reg. is in the thread structure
		 */
		if ((unsigned int)data != 0)
			return -EINVAL;
		child->thread.ufpu.fpc = data >> (BITS_PER_LONG - 32);

	} else if (addr < offsetof(struct user, regs.fp_regs) + sizeof(s390_fp_regs)) {
		/*
		 * floating point regs. are in the child->thread.ufpu.vxrs array
		 */
		offset = addr - offsetof(struct user, regs.fp_regs.fprs);
		*(addr_t *)((addr_t)child->thread.ufpu.vxrs + 2 * offset) = data;
	} else if (addr < offsetof(struct user, regs.per_info) + sizeof(per_struct)) {
		/*
		 * Handle access to the per_info structure.
		 */
		addr -= offsetof(struct user, regs.per_info);
		__poke_user_per(child, addr, data);

	}

	return 0;
}

static int poke_user(struct task_struct *child, addr_t addr, addr_t data)
{
	addr_t mask;

	/*
	 * Stupid gdb peeks/pokes the access registers in 64 bit with
	 * an alignment of 4. Programmers from hell indeed...
	 */
	mask = __ADDR_MASK;
	if (addr >= offsetof(struct user, regs.acrs) &&
	    addr < offsetof(struct user, regs.orig_gpr2))
		mask = 3;
	if ((addr & mask) || addr > sizeof(struct user) - __ADDR_MASK)
		return -EIO;

	return __poke_user(child, addr, data);
}

long arch_ptrace(struct task_struct *child, long request,
		 unsigned long addr, unsigned long data)
{
	ptrace_area parea;
	int copied, ret;

	switch (request) {
	case PTRACE_PEEKUSR:
		/* read the word at location addr in the USER area. */
		return peek_user(child, addr, data);

	case PTRACE_POKEUSR:
		/* write the word at location addr in the USER area */
		return poke_user(child, addr, data);

	case PTRACE_PEEKUSR_AREA:
	case PTRACE_POKEUSR_AREA:
		if (copy_from_user(&parea, (void __force __user *) addr,
							sizeof(parea)))
			return -EFAULT;
		addr = parea.kernel_addr;
		data = parea.process_addr;
		copied = 0;
		while (copied < parea.len) {
			if (request == PTRACE_PEEKUSR_AREA)
				ret = peek_user(child, addr, data);
			else {
				addr_t utmp;
				if (get_user(utmp,
					     (addr_t __force __user *) data))
					return -EFAULT;
				ret = poke_user(child, addr, utmp);
			}
			if (ret)
				return ret;
			addr += sizeof(unsigned long);
			data += sizeof(unsigned long);
			copied += sizeof(unsigned long);
		}
		return 0;
	case PTRACE_GET_LAST_BREAK:
		return put_user(child->thread.last_break, (unsigned long __user *)data);
	case PTRACE_ENABLE_TE:
		if (!machine_has_tx())
			return -EIO;
		child->thread.per_flags &= ~PER_FLAG_NO_TE;
		return 0;
	case PTRACE_DISABLE_TE:
		if (!machine_has_tx())
			return -EIO;
		child->thread.per_flags |= PER_FLAG_NO_TE;
		child->thread.per_flags &= ~PER_FLAG_TE_ABORT_RAND;
		return 0;
	case PTRACE_TE_ABORT_RAND:
		if (!machine_has_tx() || (child->thread.per_flags & PER_FLAG_NO_TE))
			return -EIO;
		switch (data) {
		case 0UL:
			child->thread.per_flags &= ~PER_FLAG_TE_ABORT_RAND;
			break;
		case 1UL:
			child->thread.per_flags |= PER_FLAG_TE_ABORT_RAND;
			child->thread.per_flags |= PER_FLAG_TE_ABORT_RAND_TEND;
			break;
		case 2UL:
			child->thread.per_flags |= PER_FLAG_TE_ABORT_RAND;
			child->thread.per_flags &= ~PER_FLAG_TE_ABORT_RAND_TEND;
			break;
		default:
			return -EINVAL;
		}
		return 0;
	default:
		return ptrace_request(child, request, addr, data);
	}
}

/*
 * user_regset definitions.
 */

static int s390_regs_get(struct task_struct *target,
			 const struct user_regset *regset,
			 struct membuf to)
{
	unsigned pos;
	if (target == current)
		save_access_regs(target->thread.acrs);

	for (pos = 0; pos < sizeof(s390_regs); pos += sizeof(long))
		membuf_store(&to, __peek_user(target, pos));
	return 0;
}

static int s390_regs_set(struct task_struct *target,
			 const struct user_regset *regset,
			 unsigned int pos, unsigned int count,
			 const void *kbuf, const void __user *ubuf)
{
	int rc = 0;

	if (target == current)
		save_access_regs(target->thread.acrs);

	if (kbuf) {
		const unsigned long *k = kbuf;
		while (count > 0 && !rc) {
			rc = __poke_user(target, pos, *k++);
			count -= sizeof(*k);
			pos += sizeof(*k);
		}
	} else {
		const unsigned long  __user *u = ubuf;
		while (count > 0 && !rc) {
			unsigned long word;
			rc = __get_user(word, u++);
			if (rc)
				break;
			rc = __poke_user(target, pos, word);
			count -= sizeof(*u);
			pos += sizeof(*u);
		}
	}

	if (rc == 0 && target == current)
		restore_access_regs(target->thread.acrs);

	return rc;
}

static int s390_fpregs_get(struct task_struct *target,
			   const struct user_regset *regset,
			   struct membuf to)
{
	_s390_fp_regs fp_regs;

	if (target == current)
		save_user_fpu_regs();

	fp_regs.fpc = target->thread.ufpu.fpc;
	fpregs_store(&fp_regs, &target->thread.ufpu);

	return membuf_write(&to, &fp_regs, sizeof(fp_regs));
}

static int s390_fpregs_set(struct task_struct *target,
			   const struct user_regset *regset, unsigned int pos,
			   unsigned int count, const void *kbuf,
			   const void __user *ubuf)
{
	int rc = 0;
	freg_t fprs[__NUM_FPRS];

	if (target == current)
		save_user_fpu_regs();
	convert_vx_to_fp(fprs, target->thread.ufpu.vxrs);
	if (count > 0 && pos < offsetof(s390_fp_regs, fprs)) {
		u32 ufpc[2] = { target->thread.ufpu.fpc, 0 };
		rc = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &ufpc,
					0, offsetof(s390_fp_regs, fprs));
		if (rc)
			return rc;
		if (ufpc[1] != 0)
			return -EINVAL;
		target->thread.ufpu.fpc = ufpc[0];
	}

	if (rc == 0 && count > 0)
		rc = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
					fprs, offsetof(s390_fp_regs, fprs), -1);
	if (rc)
		return rc;
	convert_fp_to_vx(target->thread.ufpu.vxrs, fprs);
	return rc;
}

static int s390_last_break_get(struct task_struct *target,
			       const struct user_regset *regset,
			       struct membuf to)
{
	return membuf_store(&to, target->thread.last_break);
}

static int s390_last_break_set(struct task_struct *target,
			       const struct user_regset *regset,
			       unsigned int pos, unsigned int count,
			       const void *kbuf, const void __user *ubuf)
{
	return 0;
}

static int s390_tdb_get(struct task_struct *target,
			const struct user_regset *regset,
			struct membuf to)
{
	struct pt_regs *regs = task_pt_regs(target);
	size_t size;

	if (!(regs->int_code & 0x200))
		return -ENODATA;
	size = sizeof(target->thread.trap_tdb.data);
	return membuf_write(&to, target->thread.trap_tdb.data, size);
}

static int s390_tdb_set(struct task_struct *target,
			const struct user_regset *regset,
			unsigned int pos, unsigned int count,
			const void *kbuf, const void __user *ubuf)
{
	return 0;
}

static int s390_vxrs_low_get(struct task_struct *target,
			     const struct user_regset *regset,
			     struct membuf to)
{
	__u64 vxrs[__NUM_VXRS_LOW];
	int i;

	if (!cpu_has_vx())
		return -ENODEV;
	if (target == current)
		save_user_fpu_regs();
	for (i = 0; i < __NUM_VXRS_LOW; i++)
		vxrs[i] = target->thread.ufpu.vxrs[i].low;
	return membuf_write(&to, vxrs, sizeof(vxrs));
}

static int s390_vxrs_low_set(struct task_struct *target,
			     const struct user_regset *regset,
			     unsigned int pos, unsigned int count,
			     const void *kbuf, const void __user *ubuf)
{
	__u64 vxrs[__NUM_VXRS_LOW];
	int i, rc;

	if (!cpu_has_vx())
		return -ENODEV;
	if (target == current)
		save_user_fpu_regs();

	for (i = 0; i < __NUM_VXRS_LOW; i++)
		vxrs[i] = target->thread.ufpu.vxrs[i].low;

	rc = user_regset_copyin(&pos, &count, &kbuf, &ubuf, vxrs, 0, -1);
	if (rc == 0)
		for (i = 0; i < __NUM_VXRS_LOW; i++)
			target->thread.ufpu.vxrs[i].low = vxrs[i];

	return rc;
}

static int s390_vxrs_high_get(struct task_struct *target,
			      const struct user_regset *regset,
			      struct membuf to)
{
	if (!cpu_has_vx())
		return -ENODEV;
	if (target == current)
		save_user_fpu_regs();
	return membuf_write(&to, target->thread.ufpu.vxrs + __NUM_VXRS_LOW,
			    __NUM_VXRS_HIGH * sizeof(__vector128));
}

static int s390_vxrs_high_set(struct task_struct *target,
			      const struct user_regset *regset,
			      unsigned int pos, unsigned int count,
			      const void *kbuf, const void __user *ubuf)
{
	int rc;

	if (!cpu_has_vx())
		return -ENODEV;
	if (target == current)
		save_user_fpu_regs();

	rc = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
				target->thread.ufpu.vxrs + __NUM_VXRS_LOW, 0, -1);
	return rc;
}

static int s390_system_call_get(struct task_struct *target,
				const struct user_regset *regset,
				struct membuf to)
{
	return membuf_store(&to, target->thread.system_call);
}

static int s390_system_call_set(struct task_struct *target,
				const struct user_regset *regset,
				unsigned int pos, unsigned int count,
				const void *kbuf, const void __user *ubuf)
{
	unsigned int *data = &target->thread.system_call;
	return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
				  data, 0, sizeof(unsigned int));
}

static int s390_gs_cb_get(struct task_struct *target,
			  const struct user_regset *regset,
			  struct membuf to)
{
	struct gs_cb *data = target->thread.gs_cb;

	if (!cpu_has_gs())
		return -ENODEV;
	if (!data)
		return -ENODATA;
	if (target == current)
		save_gs_cb(data);
	return membuf_write(&to, data, sizeof(struct gs_cb));
}

static int s390_gs_cb_set(struct task_struct *target,
			  const struct user_regset *regset,
			  unsigned int pos, unsigned int count,
			  const void *kbuf, const void __user *ubuf)
{
	struct gs_cb gs_cb = { }, *data = NULL;
	int rc;

	if (!cpu_has_gs())
		return -ENODEV;
	if (!target->thread.gs_cb) {
		data = kzalloc_obj(*data);
		if (!data)
			return -ENOMEM;
	}
	if (!target->thread.gs_cb)
		gs_cb.gsd = 25;
	else if (target == current)
		save_gs_cb(&gs_cb);
	else
		gs_cb = *target->thread.gs_cb;
	rc = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
				&gs_cb, 0, sizeof(gs_cb));
	if (rc) {
		kfree(data);
		return -EFAULT;
	}
	preempt_disable();
	if (!target->thread.gs_cb)
		target->thread.gs_cb = data;
	*target->thread.gs_cb = gs_cb;
	if (target == current) {
		local_ctl_set_bit(2, CR2_GUARDED_STORAGE_BIT);
		restore_gs_cb(target->thread.gs_cb);
	}
	preempt_enable();
	return rc;
}

static int s390_gs_bc_get(struct task_struct *target,
			  const struct user_regset *regset,
			  struct membuf to)
{
	struct gs_cb *data = target->thread.gs_bc_cb;

	if (!cpu_has_gs())
		return -ENODEV;
	if (!data)
		return -ENODATA;
	return membuf_write(&to, data, sizeof(struct gs_cb));
}

static int s390_gs_bc_set(struct task_struct *target,
			  const struct user_regset *regset,
			  unsigned int pos, unsigned int count,
			  const void *kbuf, const void __user *ubuf)
{
	struct gs_cb *data = target->thread.gs_bc_cb;

	if (!cpu_has_gs())
		return -ENODEV;
	if (!data) {
		data = kzalloc_obj(*data);
		if (!data)
			return -ENOMEM;
		target->thread.gs_bc_cb = data;
	}
	return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
				  data, 0, sizeof(struct gs_cb));
}

static bool is_ri_cb_valid(struct runtime_instr_cb *cb)
{
	return (cb->rca & 0x1f) == 0 &&
		(cb->roa & 0xfff) == 0 &&
		(cb->rla & 0xfff) == 0xfff &&
		cb->s == 1 &&
		cb->k == 1 &&
		cb->h == 0 &&
		cb->reserved1 == 0 &&
		cb->ps == 1 &&
		cb->qs == 0 &&
		cb->pc == 1 &&
		cb->qc == 0 &&
		cb->reserved2 == 0 &&
		cb->reserved3 == 0 &&
		cb->reserved4 == 0 &&
		cb->reserved5 == 0 &&
		cb->reserved6 == 0 &&
		cb->reserved7 == 0 &&
		cb->reserved8 == 0 &&
		cb->rla >= cb->roa &&
		cb->rca >= cb->roa &&
		cb->rca <= cb->rla+1 &&
		cb->m < 3;
}

static int s390_runtime_instr_get(struct task_struct *target,
				const struct user_regset *regset,
				struct membuf to)
{
	struct runtime_instr_cb *data = target->thread.ri_cb;

	if (!test_facility(64))
		return -ENODEV;
	if (!data)
		return -ENODATA;

	return membuf_write(&to, data, sizeof(struct runtime_instr_cb));
}

static int s390_runtime_instr_set(struct task_struct *target,
				  const struct user_regset *regset,
				  unsigned int pos, unsigned int count,
				  const void *kbuf, const void __user *ubuf)
{
	struct runtime_instr_cb ri_cb = { }, *data = NULL;
	int rc;

	if (!test_facility(64))
		return -ENODEV;

	if (!target->thread.ri_cb) {
		data = kzalloc_obj(*data);
		if (!data)
			return -ENOMEM;
	}

	if (target->thread.ri_cb) {
		if (target == current)
			store_runtime_instr_cb(&ri_cb);
		else
			ri_cb = *target->thread.ri_cb;
	}

	rc = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
				&ri_cb, 0, sizeof(struct runtime_instr_cb));
	if (rc) {
		kfree(data);
		return -EFAULT;
	}

	if (!is_ri_cb_valid(&ri_cb)) {
		kfree(data);
		return -EINVAL;
	}
	/*
	 * Override access key in any case, since user space should
	 * not be able to set it, nor should it care about it.
	 */
	ri_cb.key = PAGE_DEFAULT_KEY >> 4;
	preempt_disable();
	if (!target->thread.ri_cb)
		target->thread.ri_cb = data;
	*target->thread.ri_cb = ri_cb;
	if (target == current)
		load_runtime_instr_cb(target->thread.ri_cb);
	preempt_enable();

	return 0;
}

static const struct user_regset s390_regsets[] = {
	{
		USER_REGSET_NOTE_TYPE(PRSTATUS),
		.n = sizeof(s390_regs) / sizeof(long),
		.size = sizeof(long),
		.align = sizeof(long),
		.regset_get = s390_regs_get,
		.set = s390_regs_set,
	},
	{
		USER_REGSET_NOTE_TYPE(PRFPREG),
		.n = sizeof(s390_fp_regs) / sizeof(long),
		.size = sizeof(long),
		.align = sizeof(long),
		.regset_get = s390_fpregs_get,
		.set = s390_fpregs_set,
	},
	{
		USER_REGSET_NOTE_TYPE(S390_SYSTEM_CALL),
		.n = 1,
		.size = sizeof(unsigned int),
		.align = sizeof(unsigned int),
		.regset_get = s390_system_call_get,
		.set = s390_system_call_set,
	},
	{
		USER_REGSET_NOTE_TYPE(S390_LAST_BREAK),
		.n = 1,
		.size = sizeof(long),
		.align = sizeof(long),
		.regset_get = s390_last_break_get,
		.set = s390_last_break_set,
	},
	{
		USER_REGSET_NOTE_TYPE(S390_TDB),
		.n = 1,
		.size = 256,
		.align = 1,
		.regset_get = s390_tdb_get,
		.set = s390_tdb_set,
	},
	{
		USER_REGSET_NOTE_TYPE(S390_VXRS_LOW),
		.n = __NUM_VXRS_LOW,
		.size = sizeof(__u64),
		.align = sizeof(__u64),
		.regset_get = s390_vxrs_low_get,
		.set = s390_vxrs_low_set,
	},
	{
		USER_REGSET_NOTE_TYPE(S390_VXRS_HIGH),
		.n = __NUM_VXRS_HIGH,
		.size = sizeof(__vector128),
		.align = sizeof(__vector128),
		.regset_get = s390_vxrs_high_get,
		.set = s390_vxrs_high_set,
	},
	{
		USER_REGSET_NOTE_TYPE(S390_GS_CB),
		.n = sizeof(struct gs_cb) / sizeof(__u64),
		.size = sizeof(__u64),
		.align = sizeof(__u64),
		.regset_get = s390_gs_cb_get,
		.set = s390_gs_cb_set,
	},
	{
		USER_REGSET_NOTE_TYPE(S390_GS_BC),
		.n = sizeof(struct gs_cb) / sizeof(__u64),
		.size = sizeof(__u64),
		.align = sizeof(__u64),
		.regset_get = s390_gs_bc_get,
		.set = s390_gs_bc_set,
	},
	{
		USER_REGSET_NOTE_TYPE(S390_RI_CB),
		.n = sizeof(struct runtime_instr_cb) / sizeof(__u64),
		.size = sizeof(__u64),
		.align = sizeof(__u64),
		.regset_get = s390_runtime_instr_get,
		.set = s390_runtime_instr_set,
	},
};

static const struct user_regset_view user_s390_view = {
	.name = "s390x",
	.e_machine = EM_S390,
	.regsets = s390_regsets,
	.n = ARRAY_SIZE(s390_regsets)
};

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
	return &user_s390_view;
}

static const char *gpr_names[NUM_GPRS] = {
	"r0", "r1",  "r2",  "r3",  "r4",  "r5",  "r6",  "r7",
	"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
};

int regs_query_register_offset(const char *name)
{
	unsigned long offset;

	if (!name || *name != 'r')
		return -EINVAL;
	if (kstrtoul(name + 1, 10, &offset))
		return -EINVAL;
	if (offset >= NUM_GPRS)
		return -EINVAL;
	return offset;
}

const char *regs_query_register_name(unsigned int offset)
{
	if (offset >= NUM_GPRS)
		return NULL;
	return gpr_names[offset];
}