step.cpp

linux下的jtag调试软件

/*
 *  linux/arch/arm/kernel/ptrace.c
 *
 *  By Ross Biro 1/23/92
 * edited by Linus Torvalds
 * ARM modifications Copyright (C) 2000 Russell King
 *
 * 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.
 */

/* Modified for use in jelie by [e-mail] (2003)
 */

#include "jtagpxa250.h"
#include "stdio.h"

extern JTAGpxa250 *pxa250Ptr;



#define REG_PC	15
#define REG_PSR	16
//#define BREAKINST_ARM	0xef9f0001
#define BREAKINST_ARM   0xe1200070	/*bkpt #0*/
/* fill this in later */
#define BREAKINST_THUMB	0xdf00

#define predicate(x)    (x & 0xf0000000)
#define PREDICATE_ALWAYS        0xe0000000

#define PCMASK (0x3)

#define pc_pointer(v)  ((v) & ~PCMASK)

#define CC_C_BIT        (1 << 29)

typedef unsigned int u32;
typedef unsigned short u16;


union debug_insn {
        u32     arm;
        u16     thumb;
};

struct debug_entry {
        u32                     address;
        union debug_insn        insn;
};

struct debug_info {
        int                     nsaved;
        struct debug_entry      bp[2];
};


static inline unsigned int hweight16(unsigned int w)
{
unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555);
        res = (res & 0x3333) + ((res >> 2) & 0x3333);
        res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F);
        return (res & 0x00FF) + ((res >> 8) & 0x00FF);
}


/*
 * this routine will get a word off of the processes privileged stack.
 * the offset is how far from the base addr as stored in the THREAD.
 * this routine assumes that all the privileged stacks are in our
 * data space.
 */
static inline long get_user_reg(int offset)
{
	return pxa250Ptr->getSavePlace(offset);
}

/*
 * this routine will put a word on the processes privileged stack.
 * the offset is how far from the base addr as stored in the THREAD.
 * this routine assumes that all the privileged stacks are in our
 * data space.
 */
static inline int
put_user_reg(int offset, long data)
{
	pxa250Ptr->setSavePlace(offset,data);
	return 0;
}

static inline int
read_u32(unsigned long addr, u32 *res)
{
	int ret;

	if (addr & 0x3) {
		printf("FIXME: unalligned access not performed - returning crap\n");
	} else {
		pxa250Ptr->getData(addr, 1, res);
	}
	
	return 0;
}

static inline int
read_instr(unsigned long addr, u32 *res)
{
	int ret;
	u32 val;
	pxa250Ptr->getData(addr, 1, res);

	return 0;
}

/*
 * Get value of register `rn' (in the instruction)
 */
static unsigned long
jelie_getrn(unsigned long insn)
{
	unsigned int reg = (insn >> 16) & 15;
	unsigned long val;

	val = get_user_reg(reg);
	if (reg == 15)
		val = pc_pointer(val + 8);

	return val;
}

/*
 * Get value of operand 2 (in an ALU instruction)
 */
static unsigned long
jelie_getaluop2(unsigned long insn)
{
	unsigned long val;
	int shift;
	int type;

	if (insn & 1 << 25) {
		val = insn & 255;
		shift = (insn >> 8) & 15;
		type = 3;
	} else {
		val = get_user_reg (insn & 15);

		if (insn & (1 << 4))
			shift = (int)get_user_reg ((insn >> 8) & 15);
		else
			shift = (insn >> 7) & 31;

		type = (insn >> 5) & 3;
	}

	switch (type) {
	case 0:	val <<= shift;	break;
	case 1:	val >>= shift;	break;
	case 2:
		val = (((signed long)val) >> shift);
		break;
	case 3:
 		val = (val >> shift) | (val << (32 - shift));
		break;
	}
	return val;
}

/*
 * Get value of operand 2 (in a LDR instruction)
 */
static unsigned long
jelie_getldrop2(unsigned long insn)
{
	unsigned long val;
	int shift;
	int type;

	val = get_user_reg(insn & 15);
	shift = (insn >> 7) & 31;
	type = (insn >> 5) & 3;

	switch (type) {
	case 0:	val <<= shift;	break;
	case 1:	val >>= shift;	break;
	case 2:
		val = (((signed long)val) >> shift);
		break;
	case 3:
 		val = (val >> shift) | (val << (32 - shift));
		break;
	}
	return val;
}

#define OP_MASK	0x01e00000
#define OP_AND	0x00000000
#define OP_EOR	0x00200000
#define OP_SUB	0x00400000
#define OP_RSB	0x00600000
#define OP_ADD	0x00800000
#define OP_ADC	0x00a00000
#define OP_SBC	0x00c00000
#define OP_RSC	0x00e00000
#define OP_ORR	0x01800000
#define OP_MOV	0x01a00000
#define OP_BIC	0x01c00000
#define OP_MVN	0x01e00000

static unsigned long
get_branch_address(unsigned long pc, unsigned long insn)
{
	u32 alt = 0;

	switch (insn & 0x0e000000) {
	case 0x00000000:
	case 0x02000000: {
		/*
		 * data processing
		 */
		long aluop1, aluop2, ccbit;

		if ((insn & 0xf000) != 0xf000)
			break;

		aluop1 = jelie_getrn(insn);
		aluop2 = jelie_getaluop2(insn);
		ccbit  = get_user_reg(REG_PSR) & CC_C_BIT ? 1 : 0;

		switch (insn & OP_MASK) {
		case OP_AND: alt = aluop1 & aluop2;		break;
		case OP_EOR: alt = aluop1 ^ aluop2;		break;
		case OP_SUB: alt = aluop1 - aluop2;		break;
		case OP_RSB: alt = aluop2 - aluop1;		break;
		case OP_ADD: alt = aluop1 + aluop2;		break;
		case OP_ADC: alt = aluop1 + aluop2 + ccbit;	break;
		case OP_SBC: alt = aluop1 - aluop2 + ccbit;	break;
		case OP_RSC: alt = aluop2 - aluop1 + ccbit;	break;
		case OP_ORR: alt = aluop1 | aluop2;		break;
		case OP_MOV: alt = aluop2;			break;
		case OP_BIC: alt = aluop1 & ~aluop2;		break;
		case OP_MVN: alt = ~aluop2;			break;
		}
		break;
	}

	case 0x04000000:
	case 0x06000000:
		/*
		 * ldr
		 */
		if ((insn & 0x0010f000) == 0x0010f000) {
			unsigned long base;

			base = jelie_getrn(insn);
			if (insn & 1 << 24) {
				long aluop2;

				if (insn & 0x02000000)
					aluop2 = jelie_getldrop2( insn);
				else
					aluop2 = insn & 0xfff;

				if (insn & 1 << 23)
					base += aluop2;
				else
					base -= aluop2;
			}
			if (read_u32(base, &alt) == 0)
				alt = pc_pointer(alt);
		}
		break;

	case 0x08000000:
		/*
		 * ldm
		 */
		if ((insn & 0x00108000) == 0x00108000) {
			unsigned long base;
			int nr_regs;

			if (insn & (1 << 23)) {
				nr_regs = hweight16(insn & 65535) << 2;

				if (!(insn & (1 << 24)))
					nr_regs -= 4;
			} else {
				if (insn & (1 << 24))
					nr_regs = -4;
				else
					nr_regs = 0;
			}

			base = jelie_getrn(insn);

			if (read_u32(base + nr_regs, &alt) == 0)
				alt = pc_pointer(alt);
			break;
		}
		break;

	case 0x0a000000: {
		/*
		 * bl or b
		 */
		signed long displ;
		/* It's a branch/branch link: instead of trying to
		 * figure out whether the branch will be taken or not,
		 * we'll put a breakpoint at both locations.  This is
		 * simpler, more reliable, and probably not a whole lot
		 * slower than the alternative approach of emulating the
		 * branch.
		 */
		displ = (insn & 0x00ffffff) << 8;
		displ = (displ >> 6) + 8;
		if (displ != 0 && displ != 4)
			alt = pc + displ;
	    }
	    break;
	}

	return alt;
}

static int
swap_insn(unsigned long addr, void *old_insn, void *new_insn, int size)
{

	pxa250Ptr->getData(addr,1,(unsigned int *)old_insn);
	pxa250Ptr->putData(addr,1,(unsigned int *)new_insn);
	
	return 4;
}

static void
add_breakpoint(struct debug_info *dbg, unsigned long addr)
{
	int nr = dbg->nsaved;

	if (nr < 2) {
		u32 new_insn = BREAKINST_ARM;
		int res;

		res = swap_insn(addr, &dbg->bp[nr].insn, &new_insn, 4);

		if (res == 4) {
			dbg->bp[nr].address = addr;
			dbg->nsaved += 1;
			printf("software breakpoint on at %x\n",addr);
		}
	} else
		printf("too many breakpoints\n");
}

/*
 * Clear one breakpoint in the user program.  We copy what the hardware
 * does and use bit 0 of the address to indicate whether this is a Thumb
 * breakpoint or an ARM breakpoint.
 */
static void clear_breakpoint(struct debug_entry *bp)
{
	unsigned long addr = bp->address;
	union debug_insn old_insn;
	int ret;

	printf("software breakpoint off at %x\n",addr);
	ret = swap_insn(addr, &old_insn.arm,
				&bp->insn.arm, 4);

	if (ret != 4 || old_insn.arm != BREAKINST_ARM) {
		printf("corrupted ARM breakpoint at "
				"0x%08lx (0x%08x)\n",addr, old_insn.arm);
	}
}

struct debug_info dbg_s, *dbg=&dbg_s;

void jelie_set_bpt()
{
	struct pt_regs *regs;
	unsigned long pc;
	u32 insn;
	int res;

	pc=get_user_reg(REG_PC);

	res = read_instr(pc, &insn);
	if (!res) {
		unsigned long alt;

		dbg->nsaved = 0;

		alt = get_branch_address(pc, insn);
		if (alt)
			add_breakpoint(dbg, alt);

		/*
		 * Note that we ignore the result of setting the above
		 * breakpoint since it may fail.  When it does, this is
		 * not so much an error, but a forewarning that we may
		 * be receiving a prefetch abort shortly.
		 *
		 * If we don't set this breakpoint here, then we can
		 * loose control of the thread during single stepping.
		 */
		if (!alt || predicate(insn) != PREDICATE_ALWAYS)
			add_breakpoint(dbg, pc + 4);
	}
}

/*
 * Ensure no single-step breakpoint is pending.  Returns non-zero
 * value if child was being single-stepped.
 */
void jelie_cancel_bpt()
{
	int i, nsaved = dbg->nsaved;

	dbg->nsaved = 0;

	if (nsaved > 2) {
		printf("jelie_cancel_bpt: bogus nsaved: %d!\n", nsaved);
		nsaved = 2;
	}

	for (i = 0; i < nsaved; i++)
		clear_breakpoint(dbg->bp+i);
}