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 <linux/compat.h>
#include <trace/syscall.h>
#include <asm/segment.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/switch_to.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_SYSTEM_CALL,
	REGSET_GENERAL_EXTENDED,
};

void update_per_regs(struct task_struct *task)
{
	struct pt_regs *regs = task_pt_regs(task);
	struct thread_struct *thread = &task->thread;
	struct per_regs old, new;

	/* Copy user specified PER registers */
	new.control = thread->per_user.control;
	new.start = thread->per_user.start;
	new.end = thread->per_user.end;

	/* merge TIF_SINGLE_STEP into user specified PER registers. */
	if (test_tsk_thread_flag(task, TIF_SINGLE_STEP)) {
		new.control |= PER_EVENT_IFETCH;
		new.start = 0;
		new.end = PSW_ADDR_INSN;
	}

	/* 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 == (addr_t) &dummy->cr10)
		/* Start address of the active per set. */
		return test_thread_flag(TIF_SINGLE_STEP) ?
			0 : child->thread.per_user.start;
	else if (addr == (addr_t) &dummy->cr11)
		/* End address of the active per set. */
		return test_thread_flag(TIF_SINGLE_STEP) ?
			PSW_ADDR_INSN : child->thread.per_user.end;
	else if (addr == (addr_t) &dummy->bits)
		/* Single-step bit. */
		return test_thread_flag(TIF_SINGLE_STEP) ?
			(1UL << (BITS_PER_LONG - 1)) : 0;
	else if (addr == (addr_t) &dummy->starting_addr)
		/* Start address of the user specified per set. */
		return child->thread.per_user.start;
	else if (addr == (addr_t) &dummy->ending_addr)
		/* End address of the user specified per set. */
		return child->thread.per_user.end;
	else if (addr == (addr_t) &dummy->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 == (addr_t) &dummy->address)
		/* Address of the last PER trap */
		return child->thread.per_event.address;
	else if (addr == (addr_t) &dummy->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)
{
	struct user *dummy = NULL;
	addr_t offset, tmp;

	if (addr < (addr_t) &dummy->regs.acrs) {
		/*
		 * psw and gprs are stored on the stack
		 */
		tmp = *(addr_t *)((addr_t) &task_pt_regs(child)->psw + addr);
		if (addr == (addr_t) &dummy->regs.psw.mask)
			/* Return a clean psw mask. */
			tmp = psw_user_bits | (tmp & PSW_MASK_USER);

	} else if (addr < (addr_t) &dummy->regs.orig_gpr2) {
		/*