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

/*
 *  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/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,
};

void update_per_regs(struct task_struct *task)
{
	static const struct per_regs per_single_step = {
		.control = PER_EVENT_IFETCH,
		.start = 0,
		.end = PSW_ADDR_INSN,
	};
	struct pt_regs *regs = task_pt_regs(task);
	struct thread_struct *thread = &task->thread;
	const struct per_regs *new;
	struct per_regs old;

	/* TIF_SINGLE_STEP overrides the user specified PER registers. */
	new = test_tsk_thread_flag(task, TIF_SINGLE_STEP) ?
		&per_single_step : &thread->per_user;

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

void user_enable_single_step(struct task_struct *task)
{
	set_tsk_thread_flag(task, TIF_SINGLE_STEP);
	if (task == current)
		update_per_regs(task);
}

void user_disable_single_step(struct task_struct *task)
{
	clear_tsk_thread_flag(task, TIF_SINGLE_STEP);
	if (task == current)
		update_per_regs(task);
}

/*
 * 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);
}

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

static inline unsigned long __peek_user_per(struct task_struct *child,
					    addr_t addr)
{
	struct per_struct_kernel *dummy = NULL;

	if (addr == (addr_t) &dummy->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