ptrace.c

/*
 * 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/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/err.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>

/*
 * 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 *)task_pt_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 *)task_pt_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 = task_pt_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 = task_pt_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 */
		case 0x1: /* BNE */
		case 0x8: /* BEQZ */
		case 0x9: /* BNEZ */
		case 0xa: /* BLTZ */
		case 0xb: /* BGEZ */
		case 0xc: /* BLEZ */
		case 0xd: /* BGTZ */
			regno1 = ((insn >> 24) & 0xf);
			regno2 = ((insn >> 16) & 0xf);
			if (check_condition_src(op2, regno1, regno2, child)) {
				disp = (long)(insn << 16) >> 14;
				*next_pc = (pc & ~0x3) + disp;
				return;
			}
			break;
		}
	}
	*next_pc = pc + 4;
}

static inline void
compute_next_pc(unsigned long insn, unsigned long pc,
		unsigned long *next_pc, struct task_struct *child)
{
	if (insn & 0x80000000)
		compute_next_pc_for_32bit_insn(insn, pc, next_pc, child);
	else
		compute_next_pc_for_16bit_insn(insn, pc, next_pc, child);
}

static int
register_debug_trap(struct task_struct *child, unsigned long next_pc,
	unsigned long next_insn, unsigned long *code)
{
	struct debug_trap *p = &child->thread.debug_trap;
	unsigned long addr = next_pc & ~3;

	if (p->nr_trap == MAX_TRAPS) {
		printk("kernel BUG at %s %d: p->nr_trap = %d\n",
					__FILE__, __LINE__, p->nr_trap);
		return -1;
	}
	p->addr[p->nr_trap] = addr;
	p->insn[p->nr_trap] = next_insn;
	p->nr_trap++;
	if (next_pc & 3) {
		*code = (next_insn & 0xffff0000) | 0x10f1;
		/* xxx --> TRAP1 */
	} else {
		if ((next_insn & 0x80000000) || (next_insn & 0x8000)) {
			*code = 0x10f17000;
			/* TRAP1 --> NOP */
		} else {
			*code = (next_insn & 0xffff) | 0x10f10000;
			/* TRAP1 --> xxx */
		}
	}
	return 0;
}

static int
unregister_debug_trap(struct task_struct *child, unsigned long addr,
		      unsigned long *code)
{
	struct debug_trap *p = &child->thread.debug_trap;
        int i;

	/* Search debug trap entry. */
	for (i = 0; i < p->nr_trap; i++) {
		if (p->addr[i] == addr)
			break;
	}
	if (i >= p->nr_trap) {
		/* The trap may be requested from debugger.
		 * ptrace should do nothing in this case.
		 */
		return 0;
	}

	/* Recover original instruction code. */
	*code = p->insn[i];

	/* Shift debug trap entries. */
	while (i < p->nr_trap - 1) {
		p->insn[i] = p->insn[i + 1];
		p->addr[i] = p->addr[i + 1];
		i++;
	}
	p->nr_trap--;
	return 1;
}

static void
unregister_all_debug_traps(struct task_struct *child)
{
	struct debug_trap *p = &child->thread.debug_trap;
	int i;

	for (i = 0; i < p->nr_trap; i++)
		access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]), 1);
	p->nr_trap = 0;
}

static inline void
invalidate_cache(void)
{
#if defined(CONFIG_CHIP_M32700) || defined(CONFIG_CHIP_OPSP)

	_flush_cache_copyback_all();

#else	/* ! CONFIG_CHIP_M32700 */

	/* Invalidate cache */
	__asm__ __volatile__ (
                "ldi    r0, #-1					\n\t"
                "ldi    r1, #0					\n\t"
                "stb    r1, @r0		; cache off		\n\t"
                ";						\n\t"
                "ldi    r0, #-2					\n\t"
                "ldi    r1, #1					\n\t"
                "stb    r1, @r0		; cache invalidate	\n\t"
                ".fillinsn					\n"
                "0:						\n\t"
                "ldb    r1, @r0		; invalidate check	\n\t"
                "bnez   r1, 0b					\n\t"
                ";						\n\t"
                "ldi    r0, #-1					\n\t"
                "ldi    r1, #1					\n\t"
                "stb    r1, @r0		; cache on		\n\t"
		: : : "r0", "r1", "memory"
	);
	/* FIXME: copying-back d-cache and invalidating i-cache are needed.
	 */
#endif	/* CONFIG_CHIP_M32700 */
}

/* Embed a debug trap (TRAP1) code */
static int
embed_debug_trap(struct task_struct *child, unsigned long next_pc)
{
	unsigned long next_insn, code;
	unsigned long addr = next_pc & ~3;

	if (access_process_vm(child, addr, &next_insn, sizeof(next_insn), 0)
	    != sizeof(next_insn)) {
		return -1; /* error */
	}

	/* Set a trap code. */
	if (register_debug_trap(child, next_pc, next_insn, &code)) {
		return -1; /* error */
	}
	if (access_process_vm(child, addr, &code, sizeof(code), 1)
	    != sizeof(code)) {
		return -1; /* error */
	}
	return 0; /* success */
}

void
withdraw_debug_trap(struct pt_regs *regs)
{
	unsigned long addr;
	unsigned long code;

 	addr = (regs->bpc - 2) & ~3;
	regs->bpc -= 2;
	if (unregister_debug_trap(current, addr, &code)) {
	    access_process_vm(current, addr, &code, sizeof(code), 1);
	    invalidate_cache();
	}
}

void
init_debug_traps(struct task_struct *child)
{
	struct debug_trap *p = &child->thread.debug_trap;
	int i;
	p->nr_trap = 0;
	for (i = 0; i < MAX_TRAPS; i++) {
		p->addr[i] = 0;
		p->insn[i] = 0;
	}
}


/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure single step bits etc are not set.
 */
void ptrace_disable(struct task_struct *child)
{
	/* nothing to do.. */
}

long
arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
	int ret;

	switch (request) {
	/*
	 * read word at location "addr" in the child process.
	 */
	case PTRACE_PEEKTEXT:
	case PTRACE_PEEKDATA:
		ret = generic_ptrace_peekdata(child, addr, data);
		break;

	/*
	 * read the word at location addr in the USER area.
	 */
	case PTRACE_PEEKUSR:
		ret = ptrace_read_user(child, addr,
				       (unsigned long __user *)data);
		break;

	/*
	 * write the word at location addr.
	 */
	case PTRACE_POKETEXT:
	case PTRACE_POKEDATA:
		ret = generic_ptrace_pokedata(child, addr, data);
		if (ret == 0 && request == PTRACE_POKETEXT)
			invalidate_cache();
		break;

	/*
	 * write the word at location addr in the USER area.
	 */
	case PTRACE_POKEUSR:
		ret = ptrace_write_user(child, addr, data);
		break;

	/*
	 * continue/restart and stop at next (return from) syscall
	 */
	case PTRACE_SYSCALL:
	case PTRACE_CONT:
		ret = -EIO;
		if (!valid_signal(data))
			break;
		if (request == PTRACE_SYSCALL)
			set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
		else
			clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
		child->exit_code = data;
		wake_up_process(child);
		ret = 0;
		break;

	/*
	 * make the child exit.  Best I can do is send it a sigkill.
	 * perhaps it should be put in the status that it wants to
	 * exit.
	 */
	case PTRACE_KILL: {
		ret = 0;
		unregister_all_debug_traps(child);
		invalidate_cache();
		if (child->exit_state == EXIT_ZOMBIE)	/* already dead */
			break;
		child->exit_code = SIGKILL;
		wake_up_process(child);
		break;
	}

	/*
	 * execute single instruction.
	 */
	case PTRACE_SINGLESTEP: {
		unsigned long next_pc;
		unsigned long pc, insn;

		ret = -EIO;
		if (!valid_signal(data))
			break;
		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

		/* Compute next pc.  */
		pc = get_stack_long(child, PT_BPC);

		if (access_process_vm(child, pc&~3, &insn, sizeof(insn), 0)
		    != sizeof(insn))
			break;

		compute_next_pc(insn, pc, &next_pc, child);
		if (next_pc & 0x80000000)
			break;

		if (embed_debug_trap(child, next_pc))
			break;

		invalidate_cache();
		child->exit_code = data;

		/* give it a chance to run. */
		wake_up_process(child);
		ret = 0;
		break;
	}

	case PTRACE_GETREGS:
		ret = ptrace_getregs(child, (void __user *)data);
		break;

	case PTRACE_SETREGS:
		ret = ptrace_setregs(child, (void __user *)data);
		break;

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

	return ret;
}

/* notification of system call entry/exit
 * - triggered by current->work.syscall_trace
 */
void do_syscall_trace(void)
{
	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		return;
	if (!(current->ptrace & PT_PTRACED))
		return;
	/* the 0x80 provides a way for the tracing parent to distinguish
	   between a syscall stop and SIGTRAP delivery */
	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
				 ? 0x80 : 0));

	/*
	 * this isn't the same as continuing with a signal, but it will do
	 * for normal use.  strace only continues with a signal if the
	 * stopping signal is not SIGTRAP.  -brl
	 */
	if (current->exit_code) {
		send_sig(current->exit_code, current, 1);
		current->exit_code = 0;
	}
}