path: root/arch/s390/kernel/ptrace.c

/*
 *  arch/s390/kernel/ptrace.c
 *
 *  S390 version
 *    Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
 *
 *  Based on PowerPC version 
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Derived from "arch/m68k/kernel/ptrace.c"
 *  Copyright (C) 1994 by Hamish Macdonald
 *  Taken from linux/kernel/ptrace.c and modified for M680x0.
 *  linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
 *
 * Modified by Cort Dougan (cort@cs.nmt.edu) 
 *
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file README.legal in the main directory of
 * this archive for more details.
 */

#include <linux/kernel.h>
#include <linux/sched.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/tracehook.h>
#include <linux/seccomp.h>
#include <trace/syscall.h>
#include <asm/compat.h>
#include <asm/segment.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include "entry.h"

#ifdef CONFIG_COMPAT
#include "compat_ptrace.h"
#endif

#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>

enum s390_regset {
	REGSET_GENERAL,
	REGSET_FP,
	REGSET_LAST_BREAK,
	REGSET_GENERAL_EXTENDED,
};

static void
FixPerRegisters(struct task_struct *task)
{
	struct pt_regs *regs;
	per_struct *per_info;
	per_cr_words cr_words;

	regs = task_pt_regs(task);
	per_info = (per_struct *) &task->thread.per_info;
	per_info->control_regs.bits.em_instruction_fetch =
		per_info->single_step | per_info->instruction_fetch;
	
	if (per_info->single_step) {
		per_info->control_regs.bits.starting_addr = 0;
#ifdef CONFIG_COMPAT
		if (is_compat_task())
			per_info->control_regs.bits.ending_addr = 0x7fffffffUL;
		else
#endif
			per_info->control_regs.bits.ending_addr = PSW_ADDR_INSN;
	} else {
		per_info->control_regs.bits.starting_addr =
			per_info->starting_addr;
		per_info->control_regs.bits.ending_addr =
			per_info->ending_addr;
	}
	/*
	 * if any of the control reg tracing bits are on 
	 * we switch on per in the psw
	 */
	if (per_info->control_regs.words.cr[0] & PER_EM_MASK)
		regs->psw.mask |= PSW_MASK_PER;
	else
		regs->psw.mask &= ~PSW_MASK_PER;

	if (per_info->control_regs.bits.em_storage_alteration)
		per_info->control_regs.bits.storage_alt_space_ctl = 1;
	else
		per_info->control_regs.bits.storage_alt_space_ctl = 0;

	if (task == current) {
		__ctl_store(cr_words, 9, 11);
		if (memcmp(&cr_words, &per_info->control_regs.words,
			   sizeof(cr_words)) != 0)
			__ctl_load(per_info->control_regs.words, 9, 11);
	}
}

void user_enable_single_step(struct task_struct *task)
{
	task->thread.per_info.single_step = 1;
	FixPerRegisters(task);
}

void user_disable_single_step(struct task_struct *task)
{
	task->thread.per_info.single_step = 0;
	FixPerRegisters(task);
}

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure single step bits etc are not set.
 */
void
ptrace_disable(struct task_struct *child)
{
	/* make sure the single step bit is not set. */
	user_disable_single_step(child);
}

#ifndef CONFIG_64BIT
# define __ADDR_MASK 3
#else
# define __ADDR_MASK 7
#endif

/*
 * 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)
{
	struct user *dummy = NULL;
	addr_t offset, tmp;

	if (addr < (addr_t) &dummy->regs.acrs