ptrace.c

linux-2.6.15.6

/*
 * linux/arch/m32r/kernel/ptrace.c
 *
 * Copyright (C) 2002  Hirokazu Takata, Takeo Takahashi
 * Copyright (C) 2004  Hirokazu Takata, Kei Sakamoto
 *
 * Original x86 implementation:
 *	By Ross Biro 1/23/92
 *	edited by Linus Torvalds
 *
 * Some code taken from sh version:
 *   Copyright (C) 1999, 2000  Kaz Kojima & Niibe Yutaka
 * Some code taken from arm version:
 *   Copyright (C) 2000 Russell King
 */

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/string.h>
#include <linux/signal.h>

#include <asm/cacheflush.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/mmu_context.h>

/*
 * Get the address of the live pt_regs for the specified task.
 * These are saved onto the top kernel stack when the process
 * is not running.
 *
 * Note: if a user thread is execve'd from kernel space, the
 * kernel stack will not be empty on entry to the kernel, so
 * ptracing these tasks will fail.
 */
static inline struct pt_regs *
get_user_regs(struct task_struct *task)
{
        return (struct pt_regs *)
                ((unsigned long)task->thread_info + THREAD_SIZE
                 - sizeof(struct pt_regs));
}

/*
 * This routine will get a word off of the process kernel stack.
 */
static inline unsigned long int
get_stack_long(struct task_struct *task, int offset)
{
	unsigned long *stack;

	stack = (unsigned long *)get_user_regs(task);

	return stack[offset];
}

/*
 * This routine will put a word on the process kernel stack.
 */
static inline int
put_stack_long(struct task_struct *task, int offset, unsigned long data)
{
	unsigned long *stack;

	stack = (unsigned long *)get_user_regs(task);
	stack[offset] = data;

	return 0;
}

static int reg_offset[] = {
	PT_R0, PT_R1, PT_R2, PT_R3, PT_R4, PT_R5, PT_R6, PT_R7,
	PT_R8, PT_R9, PT_R10, PT_R11, PT_R12, PT_FP, PT_LR, PT_SPU,
};

/*
 * Read the word at offset "off" into the "struct user".  We
 * actually access the pt_regs stored on the kernel stack.
 */
static int ptrace_read_user(struct task_struct *tsk, unsigned long off,
			    unsigned long __user *data)
{
	unsigned long tmp;
#ifndef NO_FPU
	struct user * dummy = NULL;
#endif

	if ((off & 3) || (off < 0) || (off > sizeof(struct user) - 3))
		return -EIO;

	off >>= 2;
	switch (off) {
	case PT_EVB:
		__asm__ __volatile__ (
			"mvfc	%0, cr5 \n\t"
	 		: "=r" (tmp)
		);
		break;
	case PT_CBR: {
			unsigned long psw;
			psw = get_stack_long(tsk, PT_PSW);
			tmp = ((psw >> 8) & 1);
		}
		break;
	case PT_PSW: {
			unsigned long psw, bbpsw;
			psw = get_stack_long(tsk, PT_PSW);
			bbpsw = get_stack_long(tsk, PT_BBPSW);
			tmp = ((psw >> 8) & 0xff) | ((bbpsw & 0xff) << 8);
		}
		break;
	case PT_PC:
		tmp = get_stack_long(tsk, PT_BPC);
		break;
	case PT_BPC:
		off = PT_BBPC;
		/* fall through */
	default:
		if (off < (sizeof(struct pt_regs) >> 2))
			tmp = get_stack_long(tsk, off);
#ifndef NO_FPU
		else if (off >= (long)(&dummy->fpu >> 2) &&
			 off < (long)(&dummy->u_fpvalid >> 2)) {
			if (!tsk_used_math(tsk)) {
				if (off == (long)(&dummy->fpu.fpscr >> 2))
					tmp = FPSCR_INIT;
				else
					tmp = 0;
			} else
				tmp = ((long *)(&tsk->thread.fpu >> 2))
					[off - (long)&dummy->fpu];
		} else if (off == (long)(&dummy->u_fpvalid >> 2))
			tmp = !!tsk_used_math(tsk);
#endif /* not NO_FPU */
		else
			tmp = 0;
	}

	return put_user(tmp, data);
}

static int ptrace_write_user(struct task_struct *tsk, unsigned long off,
			     unsigned long data)
{
	int ret = -EIO;
#ifndef NO_FPU
	struct user * dummy = NULL;
#endif

	if ((off & 3) || off < 0 ||
	    off > sizeof(struct user) - 3)
		return -EIO;

	off >>= 2;
	switch (off) {
	case PT_EVB:
	case PT_BPC:
	case PT_SPI:
		/* We don't allow to modify evb. */
		ret = 0;
		break;
	case PT_PSW:
	case PT_CBR: {
			/* We allow to modify only cbr in psw */
			unsigned long psw;
			psw = get_stack_long(tsk, PT_PSW);
			psw = (psw & ~0x100) | ((data & 1) << 8);
			ret = put_stack_long(tsk, PT_PSW, psw);
		}
		break;
	case PT_PC:
		off = PT_BPC;
		data &= ~1;
		/* fall through */
	default:
		if (off < (sizeof(struct pt_regs) >> 2))
			ret = put_stack_long(tsk, off, data);
#ifndef NO_FPU
		else if (off >= (long)(&dummy->fpu >> 2) &&
			 off < (long)(&dummy->u_fpvalid >> 2)) {
			set_stopped_child_used_math(tsk);
			((long *)&tsk->thread.fpu)
				[off - (long)&dummy->fpu] = data;
			ret = 0;
		} else if (off == (long)(&dummy->u_fpvalid >> 2)) {
			conditional_stopped_child_used_math(data, tsk);
			ret = 0;
		}
#endif /* not NO_FPU */
		break;
	}

	return ret;
}

/*
 * Get all user integer registers.
 */
static int ptrace_getregs(struct task_struct *tsk, void __user *uregs)
{
	struct pt_regs *regs = get_user_regs(tsk);

	return copy_to_user(uregs, regs, sizeof(struct pt_regs)) ? -EFAULT : 0;
}

/*
 * Set all user integer registers.
 */
static int ptrace_setregs(struct task_struct *tsk, void __user *uregs)
{
	struct pt_regs newregs;
	int ret;

	ret = -EFAULT;
	if (copy_from_user(&newregs, uregs, sizeof(struct pt_regs)) == 0) {
		struct pt_regs *regs = get_user_regs(tsk);
		*regs = newregs;
		ret = 0;
	}

	return ret;
}


static inline int
check_condition_bit(struct task_struct *child)
{
	return (int)((get_stack_long(child, PT_PSW) >> 8) & 1);
}

static int
check_condition_src(unsigned long op, unsigned long regno1,
		    unsigned long regno2, struct task_struct *child)
{
	unsigned long reg1, reg2;

	reg2 = get_stack_long(child, reg_offset[regno2]);

	switch (op) {
	case 0x0: /* BEQ */
		reg1 = get_stack_long(child, reg_offset[regno1]);
		return reg1 == reg2;
	case 0x1: /* BNE */
		reg1 = get_stack_long(child, reg_offset[regno1]);
		return reg1 != reg2;
	case 0x8: /* BEQZ */
		return reg2 == 0;
	case 0x9: /* BNEZ */
		return reg2 != 0;
	case 0xa: /* BLTZ */
		return (int)reg2 < 0;
	case 0xb: /* BGEZ */
		return (int)reg2 >= 0;
	case 0xc: /* BLEZ */
		return (int)reg2 <= 0;
	case 0xd: /* BGTZ */
		return (int)reg2 > 0;
	default:
		/* never reached */
		return 0;
	}
}

static void
compute_next_pc_for_16bit_insn(unsigned long insn, unsigned long pc,
			       unsigned long *next_pc,
			       struct task_struct *child)
{
	unsigned long op, op2, op3;
	unsigned long disp;
	unsigned long regno;
	int parallel = 0;

	if (insn & 0x00008000)
		parallel = 1;
	if (pc & 3)
		insn &= 0x7fff;	/* right slot */
	else
		insn >>= 16;	/* left slot */

	op = (insn >> 12) & 0xf;
	op2 = (insn >> 8) & 0xf;
	op3 = (insn >> 4) & 0xf;

	if (op == 0x7) {
		switch (op2) {
		case 0xd: /* BNC */
		case 0x9: /* BNCL */
			if (!check_condition_bit(child)) {
				disp = (long)(insn << 24) >> 22;
				*next_pc = (pc & ~0x3) + disp;
				return;
			}
			break;
		case 0x8: /* BCL */
		case 0xc: /* BC */
			if (check_condition_bit(child)) {
				disp = (long)(insn << 24) >> 22;
				*next_pc = (pc & ~0x3) + disp;
				return;
			}
			break;
		case 0xe: /* BL */
		case 0xf: /* BRA */
			disp = (long)(insn << 24) >> 22;
			*next_pc = (pc & ~0x3) + disp;
			return;
			break;
		}
	} else if (op == 0x1) {
		switch (op2) {
		case 0x0:
			if (op3 == 0xf) { /* TRAP */
#if 1
				/* pass through */
#else
 				/* kernel space is not allowed as next_pc */
				unsigned long evb;
				unsigned long trapno;
				trapno = insn & 0xf;
				__asm__ __volatile__ (
					"mvfc %0, cr5\n"
		 			:"=r"(evb)
		 			:
				);
				*next_pc = evb + (trapno << 2);
				return;
#endif
			} else if (op3 == 0xd) { /* RTE */
				*next_pc = get_stack_long(child, PT_BPC);
				return;
			}
			break;
		case 0xc: /* JC */
			if (op3 == 0xc && check_condition_bit(child)) {
				regno = insn & 0xf;
				*next_pc = get_stack_long(child,
							  reg_offset[regno]);
				return;
			}
			break;
		case 0xd: /* JNC */
			if (op3 == 0xc && !check_condition_bit(child)) {
				regno = insn & 0xf;
				*next_pc = get_stack_long(child,
							  reg_offset[regno]);
				return;
			}
			break;
		case 0xe: /* JL */
		case 0xf: /* JMP */
			if (op3 == 0xc) { /* JMP */
				regno = insn & 0xf;
				*next_pc = get_stack_long(child,
							  reg_offset[regno]);
				return;
			}
			break;
		}
	}
	if (parallel)
		*next_pc = pc + 4;
	else
		*next_pc = pc + 2;
}

static void
compute_next_pc_for_32bit_insn(unsigned long insn, unsigned long pc,
			       unsigned long *next_pc,
			       struct task_struct *child)
{
	unsigned long op;
	unsigned long op2;
	unsigned long disp;
	unsigned long regno1, regno2;

	op = (insn >> 28) & 0xf;
	if (op == 0xf) { 	/* branch 24-bit relative */
		op2 = (insn >> 24) & 0xf;
		switch (op2) {
		case 0xd:	/* BNC */
		case 0x9:	/* BNCL */
			if (!check_condition_bit(child)) {
				disp = (long)(insn << 8) >> 6;
				*next_pc = (pc & ~0x3) + disp;
				return;
			}
			break;
		case 0x8:	/* BCL */
		case 0xc:	/* BC */
			if (check_condition_bit(child)) {
				disp = (long)(insn << 8) >> 6;
				*next_pc = (pc & ~0x3) + disp;
				return;
			}
			break;
		case 0xe:	/* BL */
		case 0xf:	/* BRA */
			disp = (long)(insn << 8) >> 6;
			*next_pc = (pc & ~0x3) + disp;
			return;
		}
	} else if (op == 0xb) { /* branch 16-bit relative */
		op2 = (insn >> 20) & 0xf;
		switch (op2) {
		case 0x0: /* BEQ */