ptrace.c

/*
 *  linux/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
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file COPYING in the main directory of
 * this archive for more details.
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/signal.h>
#include <linux/regset.h>
#include <linux/elf.h>
#include <linux/seccomp.h>
#include <linux/uaccess.h>
#include <asm/page.h>
#include <asm/processor.h>

#include "ptrace.h"

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

/* determines which bits in the SR the user has access to. */
/* 1 = access 0 = no access */
#define SR_MASK 0x001f

/* sets the trace bits. */
#define TRACE_BITS 0xC000
#define T1_BIT 0x8000
#define T0_BIT 0x4000

/* Find the stack offset for a register, relative to thread.esp0. */
#define PT_REG(reg)	((long)&((struct pt_regs *)0)->reg)
#define SW_REG(reg)	((long)&((struct switch_stack *)0)->reg \
			 - sizeof(struct switch_stack))
/* Mapping from PT_xxx to the stack offset at which the register is
   saved.  Notice that usp has no stack-slot and needs to be treated
   specially (see get_reg/put_reg below). */
static const int regoff[] = {
	[0]	= PT_REG(d1),
	[1]	= PT_REG(d2),
	[2]	= PT_REG(d3),
	[3]	= PT_REG(d4),
	[4]	= PT_REG(d5),
	[5]	= SW_REG(d6),
	[6]	= SW_REG(d7),
	[7]	= PT_REG(a0),
	[8]	= PT_REG(a1),
	[9]	= PT_REG(a2),
	[10]	= SW_REG(a3),
	[11]	= SW_REG(a4),
	[12]	= SW_REG(a5),
	[13]	= SW_REG(a6),
	[14]	= PT_REG(d0),
	[15]	= -1,
	[16]	= PT_REG(orig_d0),
	[17]	= PT_REG(sr),
	[18]	= PT_REG(pc),
};

/*
 * Get contents of register REGNO in task TASK.
 */
static inline long get_reg(struct task_struct *task, int regno)
{
	unsigned long *addr;

	if (regno == PT_USP)
		addr = &task->thread.usp;
	else if (regno < ARRAY_SIZE(regoff))
		addr = (unsigned long *)(task->thread.esp0 + regoff[regno]);
	else
		return 0;
	/* Need to take stkadj into account. */
	if (regno == PT_SR || regno == PT_PC) {
		long stkadj = *(long *)(task->thread.esp0 + PT_REG(stkadj));
		addr = (unsigned long *) ((unsigned long)addr + stkadj);
		/* The sr is actually a 16 bit register.  */
		if (regno == PT_SR)
			return *(unsigned short *)addr;
	}
	return *addr;
}

/*
 * Write contents of register REGNO in task TASK.
 */
static inline int put_reg(struct task_struct *task, int regno,
			  unsigned long data)
{
	unsigned long *addr;

	if (regno == PT_USP)
		addr = &task->thread.usp;
	else if (regno < ARRAY_SIZE(regoff))
		addr = (unsigned long *)(task->thread.esp0 + regoff[regno]);
	else
		return -1;
	/* Need to take stkadj into account. */
	if (regno == PT_SR || regno == PT_PC) {
		long stkadj = *(long *)(task->thread.esp0 + PT_REG(stkadj));
		addr = (unsigned long *) ((unsigned long)addr + stkadj);
		/* The sr is actually a 16 bit register.  */
		if (regno == PT_SR) {
			*(unsigned short *)addr = data;
			return 0;
		}
	}
	*addr = data;
	return 0;
}

/*
 * Make sure the single step bit is not set.
 */
static inline void singlestep_disable(struct task_struct *child)
{
	unsigned long tmp = get_reg(child, PT_SR) & ~TRACE_BITS;
	put_reg(child, PT_SR, tmp);
	clear_tsk_thread_flag(child, TIF_DELAYED_TRACE);
}

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

void user_enable_single_step(struct task_struct *child)
{
	unsigned long tmp = get_reg(child, PT_SR) & ~TRACE_BITS;
	put_reg(child, PT_SR, tmp | T1_BIT);
	set_tsk_thread_flag(child, TIF_DELAYED_TRACE);
}

#ifdef CONFIG_MMU
void user_enable_block_step(struct task_struct *child)
{
	unsigned long tmp = get_reg(child, PT_SR) & ~TRACE_BITS;
	put_reg(child, PT_SR, tmp | T0_BIT);
}
#endif

void user_disable_single_step(struct task_struct *child)
{
	singlestep_disable(child);
}

long arch_ptrace(struct task_struct *child, long request,
		 unsigned long addr, unsigned long data)
{
	unsigned long tmp;
	int i, ret = 0;
	int regno = addr >> 2; /* temporary hack. */
	unsigned long __user *datap = (unsigned long __user *) data;

	switch (request) {
	/* read the word at location addr in the USER area. */
	case PTRACE_PEEKUSR:
		if (addr & 3)
			goto out_eio;

		if (regno >= 0 && regno < 19) {
			tmp = get_reg(child, regno);
		} else if (regno >= 21 && regno < 49) {
			tmp = child->thread.fp[regno - 21];
			/* Convert internal fpu reg representation
			 * into long double format
			 */
			if (FPU_IS_EMU && (regno < 45) && !(regno % 3))
				tmp = ((tmp & 0xffff0000) << 15) |
				      ((tmp & 0x0000ffff) << 16);
#ifndef CONFIG_MMU
		} else if (regno == 49) {
			tmp = child->mm->start_code;
		} else if (regno == 50) {
			tmp = child->mm->start_data;
		} else if (regno == 51) {
			tmp = child->mm->end_code;
#endif
		} else
			goto out_eio;
		ret = put_user(tmp, datap);
		break;

	case PTRACE_POKEUSR:
	/* write the word at location addr in the USER area */
		if (addr & 3)
			goto out_eio;

		if (regno == PT_SR) {
			data &= SR_MASK;
			data |= get_reg(child, PT_SR) & ~SR_MASK;
		}
		if (regno >= 0 && regno < 19) {
			if (put_reg(child, regno, data))
				goto out_eio;
		} else if (regno >= 21 && regno < 48) {
			/* Convert long double format
			 * into internal fpu reg representation
			 */
			if (FPU_IS_EMU && (regno < 45) && !(regno % 3)) {
				data <<= 15;
				data = (data & 0xffff0000) |
				       ((data & 0x0000ffff) >> 1);
			}
			child->thread.fp[regno - 21] = data;
		} else
			goto out_eio;
		break;

	case PTRACE_GETREGS:	/* Get all gp regs from the child. */
		for (i = 0; i < 19; i++) {
			tmp = get_reg(child, i);
			ret = put_user(tmp, datap);
			if (ret)
				break;
			datap++;
		}
		break;

	case PTRACE_SETREGS:	/* Set all gp regs in the child. */
		for (i = 0; i < 19; i++) {
			ret = get_user(tmp, datap);
			if (ret)
				break;
			if (i == PT_SR) {
				tmp &= SR_MASK;
				tmp |= get_reg(child, PT_SR) & ~SR_MASK;
			}
			put_reg(child, i, tmp);
			datap++;
		}
		break;

	case PTRACE_GETFPREGS:	/* Get the child FPU state. */
		if (copy_to_user(datap, &child->thread.fp,
				 sizeof(struct user_m68kfp_struct)))
			ret = -EFAULT;
		break;

	case PTRACE_SETFPREGS:	/* Set the child FPU state. */
		if (copy_from_user(&child->thread.fp, datap,
				   sizeof(struct user_m68kfp_struct)))
			ret = -EFAULT;
		break;

	case PTRACE_GET_THREAD_AREA:
		ret = put_user(task_thread_info(child)->tp_value, datap);
		break;

	default:
		ret = ptrace_request(child, request, addr, data);
		break;
	}

	return ret;
out_eio:
	return -EIO;
}

asmlinkage int syscall_trace_enter(void)
{
	int ret = 0;

	if (test_thread_flag(TIF_SYSCALL_TRACE))
		ret = ptrace_report_syscall_entry(task_pt_regs(current));

	if (secure_computing() == -1)
		return -1;

	return ret;
}

asmlinkage void syscall_trace_leave(void)
{
	if (test_thread_flag(TIF_SYSCALL_TRACE))
		ptrace_report_syscall_exit(task_pt_regs(current), 0);
}

#if defined(CONFIG_BINFMT_ELF_FDPIC) && defined(CONFIG_ELF_CORE)
/*
 * Currently the only thing that needs to use regsets for m68k is the
 * coredump support of the elf_fdpic loader. Implement the minimum
 * definitions required for that.
 */
static int m68k_regset_get(struct task_struct *target,
			   const struct user_regset *regset,
			   struct membuf to)
{
	struct pt_regs *ptregs = task_pt_regs(target);
	u32 uregs[ELF_NGREG];

	ELF_CORE_COPY_REGS(uregs, ptregs);
	return membuf_write(&to, uregs, sizeof(uregs));
}

enum m68k_regset {
	REGSET_GPR,
#ifdef CONFIG_FPU
	REGSET_FPU,
#endif
};

static const struct user_regset m68k_user_regsets[] = {
	[REGSET_GPR] = {
		USER_REGSET_NOTE_TYPE(PRSTATUS),
		.n = ELF_NGREG,
		.size = sizeof(u32),
		.align = sizeof(u16),
		.regset_get = m68k_regset_get,
	},
#ifdef CONFIG_FPU
	[REGSET_FPU] = {
		USER_REGSET_NOTE_TYPE(PRFPREG),
		.n = sizeof(struct user_m68kfp_struct) / sizeof(u32),
		.size = sizeof(u32),
		.align = sizeof(u32),
	}
#endif /* CONFIG_FPU */
};

static const struct user_regset_view user_m68k_view = {
	.name = "m68k",
	.e_machine = EM_68K,
	.ei_osabi = ELF_OSABI,
	.regsets = m68k_user_regsets,
	.n = ARRAY_SIZE(m68k_user_regsets)
};

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
	return &user_m68k_view;
}
#endif /* CONFIG_BINFMT_ELF_FDPIC && CONFIG_ELF_CORE */