path: root/arch/arm64/kernel/ptrace.c

/*
 * Based on arch/arm/kernel/ptrace.c
 *
 * By Ross Biro 1/23/92
 * edited by Linus Torvalds
 * ARM modifications Copyright (C) 2000 Russell King
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/compat.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/uaccess.h>
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>
#include <linux/regset.h>
#include <linux/tracehook.h>
#include <linux/elf.h>

#include <asm/compat.h>
#include <asm/debug-monitors.h>
#include <asm/pgtable.h>
#include <asm/traps.h>
#include <asm/system_misc.h>

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

/*
 * TODO: does not yet catch signals sent when the child dies.
 * in exit.c or in signal.c.
 */

/*
 * Called by kernel/ptrace.c when detaching..
 */
void ptrace_disable(struct task_struct *child)
{
}

#ifdef CONFIG_HAVE_HW_BREAKPOINT
/*
 * Handle hitting a HW-breakpoint.
 */
static void ptrace_hbptriggered(struct perf_event *bp,
				struct perf_sample_data *data,
				struct pt_regs *regs)
{
	struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);
	siginfo_t info = {
		.si_signo	= SIGTRAP,
		.si_errno	= 0,
		.si_code	= TRAP_HWBKPT,
		.si_addr	= (void __user *)(bkpt->trigger),
	};

#ifdef CONFIG_COMPAT
	int i;

	if (!is_compat_task())
		goto send_sig;

	for (i = 0; i < ARM_MAX_BRP; ++i) {
		if (current->thread.debug.hbp_break[i] == bp) {
			info.si_errno = (i << 1) + 1;
			break;
		}
	}
	for (i = ARM_MAX_BRP; i < ARM_MAX_HBP_SLOTS && !bp; ++i) {
		if (current->thread.debug.hbp_watch[i] == bp) {
			info.si_errno = -((i << 1) + 1);
			break;
		}
	}

send_sig:
#endif
	force_sig_info(SIGTRAP, &info, current);
}

/*
 * Unregister breakpoints from this task and reset the pointers in
 * the thread_struct.
 */
void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
{
	int i;
	struct thread_struct *t = &tsk->thread;

	for (i = 0; i < ARM_MAX_BRP; i++) {
		if (t->debug.hbp_break[i]) {
			unregister_hw_breakpoint(t->debug.hbp_break[i]);
			t->debug.hbp_break[i] = NULL;
		}
	}

	for (i = 0; i < ARM_MAX_WRP; i++) {
		if (t->debug.hbp_watch[i]) {
			unregister_hw_breakpoint(t->debug.hbp_watch[i]);
			t->debug.hbp_watch[i] = NULL;
		}
	}
}

void ptrace_hw_copy_thread(struct task_struct *tsk)
{
	memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
}

static struct perf_event *ptrace_hbp_get_event(unsigned int note_type,
					       struct task_struct *tsk,
					       unsigned long idx)
{
	struct perf_event *bp = ERR_PTR(-EINVAL);

	switch (note_type) {
	case NT_ARM_HW_BREAK:
		if (idx < ARM_MAX_BRP)
			bp = tsk->thread.debug.hbp_break[idx];
		break;