kdb.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include <u.h>
#include <libc.h>
#include <bio.h>
#include <mach.h>

/*
 * Sparc-specific debugger interface
 */

static	char	*sparcexcep(Map*, Rgetter);
static	int	sparcfoll(Map*, uvlong, Rgetter, uvlong*);
static	int	sparcinst(Map*, uvlong, char, char*, int);
static	int	sparcdas(Map*, uvlong, char*, int);
static	int	sparcinstlen(Map*, uvlong);

Machdata sparcmach =
{
	{0x91, 0xd0, 0x20, 0x01},	/* breakpoint: TA $1 */
	4,			/* break point size */

	beswab,			/* convert short to local byte order */
	beswal,			/* convert long to local byte order */
	beswav,			/* convert vlong to local byte order */
	risctrace,		/* C traceback */
	riscframe,		/* frame finder */
	sparcexcep,		/* print exception */
	0,			/* breakpoint fixup */
	beieeesftos,		/* single precision float printer */
	beieeedftos,		/* double precision float printer */
	sparcfoll,		/* following addresses */
	sparcinst,		/* print instruction */
	sparcdas,		/* dissembler */
	sparcinstlen,		/* instruction size */
};

static char *trapname[] =
{
	"reset",
	"instruction access exception",
	"illegal instruction",
	"privileged instruction",
	"fp disabled",
	"window overflow",
	"window underflow",
	"unaligned address",
	"fp exception",
	"data access exception",
	"tag overflow",
};

static char*
excname(ulong tbr)
{
	static char buf[32];

	if(tbr < sizeof trapname/sizeof(char*))
		return trapname[tbr];
	if(tbr >= 130)
		sprint(buf, "trap instruction %ld", tbr-128);
	else if(17<=tbr && tbr<=31)
		sprint(buf, "interrupt level %ld", tbr-16);
	else switch(tbr){
	case 36:
		return "cp disabled";
	case 40:
		return "cp exception";
	case 128:
		return "syscall";
	case 129:
		return "breakpoint";
	default:
		sprint(buf, "unknown trap %ld", tbr);
	}
	return buf;
}

static char*
sparcexcep(Map *map, Rgetter rget)
{
	long tbr;

	tbr = (*rget)(map, "TBR");
	tbr = (tbr&0xFFF)>>4;
	return excname(tbr);
}

	/* Sparc disassembler and related functions */

struct opcode {
	char	*mnemonic;
	void	(*f)(struct instr*, char*);
	int	flag;
};

static	char FRAMENAME[] = ".frame";

typedef struct instr Instr;

struct instr {
	uchar	op;		/* bits 31-30 */
	uchar	rd;		/* bits 29-25 */
	uchar	op2;		/* bits 24-22 */
	uchar	a;		/* bit  29    */
	uchar	cond;		/* bits 28-25 */
	uchar	op3;		/* bits 24-19 */
	uchar	rs1;		/* bits 18-14 */
	uchar	i;		/* bit  13    */
	uchar	asi;		/* bits 12-05 */
	uchar	rs2;		/* bits 04-00 */
	short	simm13;		/* bits 12-00, signed */
	ushort	opf;		/* bits 13-05 */
	ulong	immdisp22;	/* bits 21-00 */
	ulong	simmdisp22;	/* bits 21-00, signed */
	ulong	disp30;		/* bits 30-00 */
	ulong	imm32;		/* SETHI+ADD constant */
	int	target;		/* SETHI+ADD dest reg */
	long	w0;
	long	w1;
	uvlong	addr;		/* pc of instruction */
	char	*curr;		/* current fill level in output buffer */
	char	*end;		/* end of buffer */
	int 	size;		/* number of longs in instr */
	char	*err;		/* errmsg */
};

static	Map	*mymap;		/* disassembler context */
static	int	dascase;

static int	mkinstr(uvlong, Instr*);
static void	bra1(Instr*, char*, char*[]);
static void	bra(Instr*, char*);
static void	fbra(Instr*, char*);
static void	cbra(Instr*, char*);
static void	unimp(Instr*, char*);
static void	fpop(Instr*, char*);
static void	shift(Instr*, char*);
static void	sethi(Instr*, char*);
static void	load(Instr*, char*);
static void	loada(Instr*, char*);
static void	store(Instr*, char*);
static void	storea(Instr*, char*);
static void	add(Instr*, char*);
static void	cmp(Instr*, char*);
static void	wr(Instr*, char*);
static void	jmpl(Instr*, char*);
static void	rd(Instr*, char*);
static void	loadf(Instr*, char*);
static void	storef(Instr*, char*);
static void	loadc(Instr*, char*);
static void	loadcsr(Instr*, char*);
static void	trap(Instr*, char*);

static struct opcode sparcop0[8] = {
	[0]	"UNIMP",	unimp,	0,	/* page 137 */
	[2]	"B",		bra,	0,	/* page 119 */
	[4]	"SETHI",	sethi,	0,	/* page 104 */
	[6]	"FB",		fbra,	0,	/* page 121 */
	[7]	"CB",		cbra,	0,	/* page 123 */
};

static struct opcode sparcop2[64] = {
	[0x00]	"ADD",		add,	0,	/* page 108 */
	[0x10]	"ADDCC",	add,	0,
	[0x08]	"ADDX",		add,	0,
	[0x18]	"ADDXCC",	add,	0,

	[0x20]	"TADD",		add,	0,	/* page 109 */
	[0x22]	"TADDCCTV",	add,	0,

	[0x04]	"SUB",		add,	0,	/* page 110 */
	[0x14]	"SUBCC",	cmp,	0,
	[0x0C]	"SUBX",		add,	0,
	[0x1C]	"SUBXCC",	add,	0,

	[0x21]	"TSUB",		add,	0,	/* page 111 */
	[0x23]	"TSUBCCTV",	add,	0,

	[0x24]	"MULSCC",	add,	0,	/* page 112 */

	[0x0A]	"UMUL",		add,	0,	/* page 113 */
	[0x0B]	"SMUL",		add,	0,
	[0x1A]	"UMULCC",	add,	0,
	[0x1B]	"SMULCC",	add,	0,

	[0x0E]	"UDIV",		add,	0,	/* page 115 */
	[0x0F]	"SDIV",		add,	0,
	[0x1E]	"UDIVCC",	add,	0,
	[0x1F]	"SDIVCC",	add,	0,

	[0x01]	"AND",		add,	0,	/* page 106 */
	[0x11]	"ANDCC",	add,	0,
	[0x05]	"ANDN",		add,	0,
	[0x15]	"ANDNCC",	add,	0,
	[0x02]	"OR",		add,	0,
	[0x12]	"ORCC",		add,	0,
	[0x06]	"ORN",		add,	0,
	[0x16]	"ORNCC",	add,	0,
	[0x03]	"XOR",		add,	0,
	[0x13]	"XORCC",	add,	0,
	[0x07]	"XORN",		add,	0,
	[0x17]	"XORNCC",	add,	0,

	[0x25]	"SLL",		shift,	0,	/* page 107 */
	[0x26]	"SRL",		shift,	0,
	[0x27]	"SRA",		shift,	0,

	[0x3C]	"SAVE",		add,	0,	/* page 117 */
	[0x3D]	"RESTORE",	add,	0,

	[0x38]	"JMPL",		jmpl,	0,	/* page 126 */

	[0x39]	"RETT",		add,	0,	/* page 127 */

	[0x3A]	"T",		trap,	0,	/* page 129 */

	[0x28]	"rdy",		rd,	0,	/* page 131 */
	[0x29]	"rdpsr",	rd,	0,
	[0x2A]	"rdwim",	rd,	0,
	[0x2B]	"rdtbr",	rd,	0,

	[0x30]	"wry",		wr,	0,	/* page 133 */
	[0x31]	"wrpsr",	wr,	0,
	[0x32]	"wrwim",	wr,	0,
	[0x33]	"wrtbr",	wr,	0,

	[0x3B]	"flush",	add,	0,	/* page 138 */

	[0x34]	"FPOP",		fpop,	0,	/* page 140 */
	[0x35]	"FPOP",		fpop,	0,
};

static struct opcode sparcop3[64]={
	[0x09]	"ldsb",		load,	0,	/* page 90 */
	[0x19]	"ldsba",	loada,	0,
	[0x0A]	"ldsh",		load,	0,
	[0x1A]	"ldsha",	loada,	0,
	[0x01]	"ldub",		load,	0,
	[0x11]	"lduba",	loada,	0,
	[0x02]	"lduh",		load,	0,
	[0x12]	"lduha",	loada,	0,
	[0x00]	"ld",		load,	0,
	[0x10]	"lda",		loada,	0,
	[0x03]	"ldd",		load,	0,
	[0x13]	"ldda",		loada,	0,

	[0x20]	"ldf",		loadf,	0,	/* page 92 */
	[0x23]	"lddf",		loadf,	0,
	[0x21]	"ldfsr",	loadf,0,

	[0x30]	"ldc",		loadc,	0,	/* page 94 */
	[0x33]	"lddc",		loadc,	0,
	[0x31]	"ldcsr",	loadcsr,0,

	[0x05]	"stb",		store,	0,	/* page 95 */
	[0x15]	"stba",		storea,	0,
	[0x06]	"sth",		store,	0,
	[0x16]	"stha",		storea,	0,
	[0x04]	"st",		store,	0,
	[0x14]	"sta",		storea,	0,
	[0x07]	"std",		store,	0,
	[0x17]	"stda",		storea,	0,

	[0x24]	"stf",		storef,	0,	/* page 97 */
	[0x27]	"stdf",		storef,	0,
	[0x25]	"stfsr",	storef,0,
	[0x26]	"stdfq",	storef,0,

	[0x34]	"stc",		loadc,	0,	/* page 99 */
	[0x37]	"stdc",		loadc,	0,
	[0x35]	"stcsr",	loadcsr,0,
	[0x36]	"stdcq",	loadcsr,0,

	[0x0D]	"ldstub",	store,	0,	/* page 101 */
	[0x1D]	"ldstuba",	storea,	0,

	[0x0F]	"swap",		load,	0,	/* page 102 */
	[0x1F]	"swapa",	loada,	0,
};

#pragma	varargck	argpos	bprint	2
#pragma	varargck	type	"T"	char*

/* convert to lower case from upper, according to dascase */
static int
Tfmt(Fmt *f)
{
	char buf[128];
	char *s, *t, *oa;

	oa = va_arg(f->args, char*);
	if(dascase){
		for(s=oa,t=buf; *t = *s; s++,t++)
			if('A'<=*t && *t<='Z')
				*t += 'a'-'A';
		return fmtstrcpy(f, buf);
	}
	return fmtstrcpy(f, oa);
}

static void
bprint(Instr *i, char *fmt, ...)
{
	va_list arg;

	va_start(arg, fmt);
	i->curr = vseprint(i->curr, i->end, fmt, arg);
	va_end(arg);
}

static int
decode(uvlong pc, Instr *i)
{
	ulong w;

	if (get4(mymap, pc, &w) < 0) {
		werrstr("can't read instruction: %r");
		return -1;
	}
	i->op = (w >> 30) & 0x03;
	i->rd = (w >> 25) & 0x1F;
	i->op2 = (w >> 22) & 0x07;
	i->a = (w >> 29) & 0x01;
	i->cond = (w >> 25) & 0x0F;
	i->op3 = (w >> 19) & 0x3F;
	i->rs1 = (w >> 14) & 0x1F;
	i->i = (w >> 13) & 0x01;
	i->asi = (w >> 5) & 0xFF;
	i->rs2 = (w >> 0) & 0x1F;
	i->simm13 = (w >> 0) & 0x1FFF;
	if(i->simm13 & (1<<12))
		i->simm13 |= ~((1<<13)-1);
	i->opf = (w >> 5) & 0x1FF;
	i->immdisp22 = (w >> 0) & 0x3FFFFF;
	i->simmdisp22 = i->immdisp22;
	if(i->simmdisp22 & (1<<21))
		i->simmdisp22 |= ~((1<<22)-1);
	i->disp30 = (w >> 0) & 0x3FFFFFFF;
	i->w0 = w;
	i->target = -1;
	i->addr = pc;
	i->size = 1;
	return 1;
}

static int
mkinstr(uvlong pc, Instr *i)
{
	Instr xi;

	if (decode(pc, i) < 0)
		return -1;
	if(i->op==0 && i->op2==4 && !dascase){	/* SETHI */
		if (decode(pc+4, &xi) < 0)
			return -1;
		if(xi.op==2 && xi.op3==0)		/* ADD */
		if(xi.i == 1 && xi.rs1 == i->rd){	/* immediate to same reg */
			i->imm32 = xi.simm13 + (i->immdisp22<<10);
			i->target = xi.rd;
			i->w1 = xi.w0;
			i->size++;
			return 1;
		}
	}
	if(i->op==2 && i->opf==1 && !dascase){	/* FMOVS */
		if (decode(pc+4, &xi) < 0)
			return -1;
		if(i->op==2 && i->opf==1)		/* FMOVS */
		if(xi.rd==i->rd+1 && xi.rs2==i->rs2+1){	/* next pair */
			i->w1 = xi.w0;
			i->size++;
		}
	}
	return 1;
}

static int
printins(Map *map, uvlong pc, char *buf, int n)
{
	Instr instr;
	void (*f)(Instr*, char*);

	mymap = map;
	memset(&instr, 0, sizeof(instr));
	instr.curr = buf;
	instr.end = buf+n-1;
	if (mkinstr(pc, &instr) < 0)
		return -1;
	switch(instr.op){
	case 0:
		f = sparcop0[instr.op2].f;
		if(f)
			(*f)(&instr, sparcop0[instr.op2].mnemonic);
		else
			bprint(&instr, "unknown %lux", instr.w0);
		break;

	case 1:
		bprint(&instr, "%T", "CALL\t");
		instr.curr += symoff(instr.curr, instr.end-instr.curr,
					pc+instr.disp30*4, CTEXT);
		if (!dascase)
			bprint(&instr, "(SB)");
		break;

	case 2:
		f = sparcop2[instr.op3].f;
		if(f)
			(*f)(&instr, sparcop2[instr.op3].mnemonic);
		else
			bprint(&instr, "unknown %lux", instr.w0);
		break;

	case 3:
		f = sparcop3[instr.op3].f;
		if(f)
			(*f)(&instr, sparcop3[instr.op3].mnemonic);
		else
			bprint(&instr, "unknown %lux", instr.w0);
		break;
	}
	if (instr.err) {
		if (instr.curr != buf)
			bprint(&instr, "\t\t;");
		bprint(&instr, instr.err);
	}
	return instr.size*4;
}

static int
sparcinst(Map *map, uvlong pc, char modifier, char *buf, int n)
{
	static int fmtinstalled = 0;

		/* a modifier of 'I' toggles the dissassembler type */
	if (!fmtinstalled) {
		fmtinstalled = 1;
		fmtinstall('T', Tfmt);
	}
	if ((asstype == ASUNSPARC && modifier == 'i')
		|| (asstype == ASPARC && modifier == 'I'))
		dascase = 'a'-'A';
	else
		dascase = 0;
	return printins(map, pc, buf, n);
}

static int
sparcdas(Map *map, uvlong pc, char *buf, int n)
{
	Instr instr;

	mymap = map;
	memset(&instr, 0, sizeof(instr));
	instr.curr = buf;
	instr.end = buf+n-1;
	if (mkinstr(pc, &instr) < 0)
		return -1;
	if (instr.end-instr.curr > 8)
		instr.curr = _hexify(instr.curr, instr.w0, 7);
	if (instr.end-instr.curr > 9 && instr.size == 2) {
		*instr.curr++ = ' ';
		instr.curr = _hexify(instr.curr, instr.w1, 7);
	}
	*instr.curr = 0;
	return instr.size*4;
}

static int
sparcinstlen(Map *map, uvlong pc)
{
	Instr i;

	mymap = map;
	if (mkinstr(pc, &i) < 0)
		return -1;
	return i.size*4;
}

static int
plocal(Instr *i)
{
	int offset;
	Symbol s;

	if (!findsym(i->addr, CTEXT, &s) || !findlocal(&s, FRAMENAME, &s))
		return -1;
	if (s.value > i->simm13) {
		if(getauto(&s, s.value-i->simm13, CAUTO, &s)) {
			bprint(i, "%s+%lld(SP)", s.name, s.value);
			return 1;
		}
	} else {
		offset = i->simm13-s.value;
		if (getauto(&s, offset-4, CPARAM, &s)) {
			bprint(i, "%s+%d(FP)", s.name, offset);
			return 1;
		}
	}
	return -1;
}

static void
address(Instr *i)
{
	Symbol s, s2;
	uvlong off, off1;

	if (i->rs1 == 1 && plocal(i) >= 0)
		return;
	off = mach->sb+i->simm13;
	if(i->rs1 == 2	&& findsym(off, CANY, &s)
			&& s.value-off < 4096
			&& (s.class == CDATA || s.class == CTEXT)) {
		if(off==s.value && s.name[0]=='$'){
			off1 = 0;
			geta(mymap, s.value, &off1);
			if(off1 && findsym(off1, CANY, &s2) && s2.value == off1){
				bprint(i, "$%s(SB)", s2.name);
				return;
			}
		}
		bprint(i, "%s", s.name);
		if (s.value != off)
			bprint(i, "+%llux", s.value-off);
		bprint(i, "(SB)");
		return;