8db.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>

/*
 * i386-specific debugger interface
 * also amd64 extensions
 */

static	char	*i386excep(Map*, Rgetter);

static	int	i386trace(Map*, uvlong, uvlong, uvlong, Tracer);
static	uvlong	i386frame(Map*, uvlong, uvlong, uvlong, uvlong);
static	int	i386foll(Map*, uvlong, Rgetter, uvlong*);
static	int	i386inst(Map*, uvlong, char, char*, int);
static	int	i386das(Map*, uvlong, char*, int);
static	int	i386instlen(Map*, uvlong);

static	char	STARTSYM[] =	"_main";
static	char	PROFSYM[] =	"_mainp";
static	char	FRAMENAME[] =	".frame";
static char *excname[] =
{
[0]	"divide error",
[1]	"debug exception",
[4]	"overflow",
[5]	"bounds check",
[6]	"invalid opcode",
[7]	"math coprocessor emulation",
[8]	"double fault",
[9]	"math coprocessor overrun",
[10]	"invalid TSS",
[11]	"segment not present",
[12]	"stack exception",
[13]	"general protection violation",
[14]	"page fault",
[16]	"math coprocessor error",
[17]	"alignment check",
[18]	"machine check",
[19]	"floating-point exception",
[24]	"clock",
[25]	"keyboard",
[27]	"modem status",
[28]	"serial line status",
[30]	"floppy disk",
[36]	"mouse",
[37]	"math coprocessor",
[38]	"hard disk",
[64]	"system call",
};

Machdata i386mach =
{
	{0xCC, 0, 0, 0},	/* break point: INT 3 */
	1,			/* break point size */

	leswab,			/* convert short to local byte order */
	leswal,			/* convert long to local byte order */
	leswav,			/* convert vlong to local byte order */
	i386trace,		/* C traceback */
	i386frame,		/* frame finder */
	i386excep,		/* print exception */
	0,			/* breakpoint fixup */
	leieeesftos,		/* single precision float printer */
	leieeedftos,		/* double precision float printer */
	i386foll,		/* following addresses */
	i386inst,		/* print instruction */
	i386das,		/* dissembler */
	i386instlen,		/* instruction size calculation */
};

static char*
i386excep(Map *map, Rgetter rget)
{
	ulong c;
	uvlong pc;
	static char buf[16];

	c = (*rget)(map, "TRAP");
	if(c > 64 || excname[c] == 0) {
		if (c == 3) {
			pc = (*rget)(map, "PC");
			if (get1(map, pc, (uchar*)buf, machdata->bpsize) > 0)
			if (memcmp(buf, machdata->bpinst, machdata->bpsize) == 0)
				return "breakpoint";
		}
		snprint(buf, sizeof(buf), "exception %ld", c);
		return buf;
	} else
		return excname[c];
}

static int
i386trace(Map *map, uvlong pc, uvlong sp, uvlong link, Tracer trace)
{
	int i;
	uvlong osp;
	Symbol s, f;

	USED(link);
	i = 0;
	osp = 0;
	while(findsym(pc, CTEXT, &s)) {
		if (osp == sp)
			break;
		osp = sp;

		if(strcmp(STARTSYM, s.name) == 0 || strcmp(PROFSYM, s.name) == 0)
			break;

		if(pc != s.value) {	/* not at first instruction */
			if(findlocal(&s, FRAMENAME, &f) == 0)
				break;
			sp += f.value-mach->szaddr;
		}

		if (geta(map, sp, &pc) < 0)
			break;

		if(pc == 0)
			break;

		(*trace)(map, pc, sp, &s);
		sp += mach->szaddr;

		if(++i > 1000)
			break;
	}
	return i;
}

static uvlong
i386frame(Map *map, uvlong addr, uvlong pc, uvlong sp, uvlong link)
{
	Symbol s, f;

	USED(link);
	while (findsym(pc, CTEXT, &s)) {
		if(strcmp(STARTSYM, s.name) == 0 || strcmp(PROFSYM, s.name) == 0)
			break;

		if(pc != s.value) {	/* not first instruction */
			if(findlocal(&s, FRAMENAME, &f) == 0)
				break;
			sp += f.value-mach->szaddr;
		}

		if (s.value == addr)
			return sp;

		if (geta(map, sp, &pc) < 0)
			break;
		sp += mach->szaddr;
	}
	return 0;
}

	/* I386/486 - Disassembler and related functions */

/*
 *  an instruction
 */
typedef struct Instr Instr;
struct	Instr
{
	uchar	mem[1+1+1+1+2+1+1+4+4];		/* raw instruction */
	uvlong	addr;		/* address of start of instruction */
	int	n;		/* number of bytes in instruction */
	char	*prefix;	/* instr prefix */
	char	*segment;	/* segment override */
	uchar	jumptype;	/* set to the operand type for jump/ret/call */
	uchar	amd64;
	uchar	rex;		/* REX prefix (or zero) */
	char	osize;		/* 'W' or 'L' (or 'Q' on amd64) */
	char	asize;		/* address size 'W' or 'L' (or 'Q' or amd64) */
	uchar	mod;		/* bits 6-7 of mod r/m field */
	uchar	reg;		/* bits 3-5 of mod r/m field */
	char	ss;		/* bits 6-7 of SIB */
	char	index;		/* bits 3-5 of SIB */
	char	base;		/* bits 0-2 of SIB */
	char	rip;		/* RIP-relative in amd64 mode */
	uchar	opre;		/* f2/f3 could introduce media */
	short	seg;		/* segment of far address */
	ulong	disp;		/* displacement */
	ulong 	imm;		/* immediate */
	ulong 	imm2;		/* second immediate operand */
	uvlong	imm64;		/* big immediate */
	char	*curr;		/* fill level in output buffer */
	char	*end;		/* end of output buffer */
	char	*err;		/* error message */
};

	/* 386 register (ha!) set */
enum{
	AX=0,
	CX,
	DX,
	BX,
	SP,
	BP,
	SI,
	DI,

	/* amd64 */
	R8,
	R9,
	R10,
	R11,
	R12,
	R13,
	R14,
	R15
};

	/* amd64 rex extension byte */
enum{
	REXW		= 1<<3,	/* =1, 64-bit operand size */
	REXR		= 1<<2,	/* extend modrm reg */
	REXX		= 1<<1,	/* extend sib index */
	REXB		= 1<<0	/* extend modrm r/m, sib base, or opcode reg */
};
	
	/* Operand Format codes */
/*
%A	-	address size register modifier (!asize -> 'E')
%C	-	Control register CR0/CR1/CR2
%D	-	Debug register DR0/DR1/DR2/DR3/DR6/DR7
%I	-	second immediate operand
%O	-	Operand size register modifier (!osize -> 'E')
%T	-	Test register TR6/TR7
%S	-	size code ('W' or 'L')
%W	-	Weird opcode: OSIZE == 'W' => "CBW"; else => "CWDE"
%d	-	displacement 16-32 bits
%e	-	effective address - Mod R/M value
%f	-	floating point register F0-F7 - from Mod R/M register
%g	-	segment register
%i	-	immediate operand 8-32 bits
%p	-	PC-relative - signed displacement in immediate field
%r	-	Reg from Mod R/M
%w	-	Weird opcode: OSIZE == 'W' => "CWD"; else => "CDQ"
*/

typedef struct Optable Optable;
struct Optable
{
	char	operand[2];
	void	*proto;		/* actually either (char*) or (Optable*) */
};
	/* Operand decoding codes */
enum {
	Ib = 1,			/* 8-bit immediate - (no sign extension)*/
	Ibs,			/* 8-bit immediate (sign extended) */
	Jbs,			/* 8-bit sign-extended immediate in jump or call */
	Iw,			/* 16-bit immediate -> imm */
	Iw2,			/* 16-bit immediate -> imm2 */
	Iwd,			/* Operand-sized immediate (no sign extension)*/
	Iwdq,			/* Operand-sized immediate, possibly 64 bits */
	Awd,			/* Address offset */
	Iwds,			/* Operand-sized immediate (sign extended) */
	RM,			/* Word or long R/M field with register (/r) */
	RMB,			/* Byte R/M field with register (/r) */
	RMOP,			/* Word or long R/M field with op code (/digit) */
	RMOPB,			/* Byte R/M field with op code (/digit) */
	RMR,			/* R/M register only (mod = 11) */
	RMM,			/* R/M memory only (mod = 0/1/2) */
	R0,			/* Base reg of Mod R/M is literal 0x00 */
	R1,			/* Base reg of Mod R/M is literal 0x01 */
	FRMOP,			/* Floating point R/M field with opcode */
	FRMEX,			/* Extended floating point R/M field with opcode */
	JUMP,			/* Jump or Call flag - no operand */
	RET,			/* Return flag - no operand */
	OA,			/* literal 0x0a byte */
	PTR,			/* Seg:Displacement addr (ptr16:16 or ptr16:32) */
	AUX,			/* Multi-byte op code - Auxiliary table */
	AUXMM,			/* multi-byte op code - auxiliary table chosen by prefix */
	PRE,			/* Instr Prefix */
	OPRE,			/* Instr Prefix or media op extension */
	SEG,			/* Segment Prefix */
	OPOVER,			/* Operand size override */
	ADDOVER,		/* Address size override */
};
	
static Optable optab0F00[8]=
{
[0x00]	0,0,		"MOVW	LDT,%e",
[0x01]	0,0,		"MOVW	TR,%e",
[0x02]	0,0,		"MOVW	%e,LDT",
[0x03]	0,0,		"MOVW	%e,TR",
[0x04]	0,0,		"VERR	%e",
[0x05]	0,0,		"VERW	%e",
};

static Optable optab0F01[8]=
{
[0x00]	0,0,		"MOVL	GDTR,%e",
[0x01]	0,0,		"MOVL	IDTR,%e",
[0x02]	0,0,		"MOVL	%e,GDTR",
[0x03]	0,0,		"MOVL	%e,IDTR",
[0x04]	0,0,		"MOVW	MSW,%e",	/* word */
[0x06]	0,0,		"MOVW	%e,MSW",	/* word */
[0x07]	0,0,		"INVLPG	%e",		/* or SWAPGS */
};

static Optable optab0F01F8[1]=
{
[0x00]	0,0,		"SWAPGS",
};

/* 0F71 */
/* 0F72 */
/* 0F73 */

static Optable optab0FAE[8]=
{
[0x00]	0,0,		"FXSAVE	%e",
[0x01]	0,0,		"FXRSTOR	%e",
[0x02]	0,0,		"LDMXCSR	%e",
[0x03]	0,0,		"STMXCSR	%e",
[0x05]	0,0,		"LFENCE",
[0x06]	0,0,		"MFENCE",
[0x07]	0,0,		"SFENCE",
};

/* 0F18 */
/* 0F0D */

static Optable optab0FBA[8]=
{
[0x04]	Ib,0,		"BT%S	%i,%e",
[0x05]	Ib,0,		"BTS%S	%i,%e",
[0x06]	Ib,0,		"BTR%S	%i,%e",
[0x07]	Ib,0,		"BTC%S	%i,%e",
};

static Optable optab0F0F[256]=
{
[0x0c]	0,0,		"PI2FW	%m,%M",
[0x0d]	0,0,		"PI2L	%m,%M",
[0x1c]	0,0,		"PF2IW	%m,%M",
[0x1d]	0,0,		"PF2IL	%m,%M",
[0x8a]	0,0,		"PFNACC	%m,%M",
[0x8e]	0,0,		"PFPNACC	%m,%M",
[0x90]	0,0,		"PFCMPGE	%m,%M",
[0x94]	0,0,		"PFMIN	%m,%M",
[0x96]	0,0,		"PFRCP	%m,%M",
[0x97]	0,0,		"PFRSQRT	%m,%M",
[0x9a]	0,0,		"PFSUB	%m,%M",
[0x9e]	0,0,		"PFADD	%m,%M",
[0xa0]	0,0,		"PFCMPGT	%m,%M",
[0xa4]	0,0,		"PFMAX	%m,%M",
[0xa6]	0,0,		"PFRCPIT1	%m,%M",
[0xa7]	0,0,		"PFRSQIT1	%m,%M",
[0xaa]	0,0,		"PFSUBR	%m,%M",
[0xae]	0,0,		"PFACC	%m,%M",
[0xb0]	0,0,		"PFCMPEQ	%m,%M",
[0xb4]	0,0,		"PFMUL	%m,%M",
[0xb6]	0,0,		"PFRCPI2T	%m,%M",
[0xb7]	0,0,		"PMULHRW	%m,%M",
[0xbb]	0,0,		"PSWAPL	%m,%M",
};

static Optable optab0FC7[8]=
{
[0x01]	0,0,		"CMPXCHG8B	%e",
};

static Optable optab660F71[8]=
{
[0x02]	Ib,0,		"PSRLW	%i,%X",
[0x04]	Ib,0,		"PSRAW	%i,%X",
[0x06]	Ib,0,		"PSLLW	%i,%X",
};

static Optable optab660F72[8]=
{
[0x02]	Ib,0,		"PSRLL	%i,%X",
[0x04]	Ib,0,		"PSRAL	%i,%X",
[0x06]	Ib,0,		"PSLLL	%i,%X",
};

static Optable optab660F73[8]=
{
[0x02]	Ib,0,		"PSRLQ	%i,%X",
[0x03]	Ib,0,		"PSRLO	%i,%X",
[0x06]	Ib,0,		"PSLLQ	%i,%X",
[0x07]	Ib,0,		"PSLLO	%i,%X",
};

static Optable optab660F[256]=
{
[0x2B]	RM,0,		"MOVNTPD	%x,%e",
[0x2E]	RM,0,		"UCOMISD	%x,%X",
[0x2F]	RM,0,		"COMISD	%x,%X",
[0x5A]	RM,0,		"CVTPD2PS	%x,%X",
[0x5B]	RM,0,		"CVTPS2PL	%x,%X",
[0x6A]	RM,0,		"PUNPCKHLQ %x,%X",
[0x6B]	RM,0,		"PACKSSLW %x,%X",
[0x6C]	RM,0,		"PUNPCKLQDQ %x,%X",
[0x6D]	RM,0,		"PUNPCKHQDQ %x,%X",
[0x6E]	RM,0,		"MOV%S	%e,%X",
[0x6F]	RM,0,		"MOVO	%x,%X",		/* MOVDQA */
[0x70]	RM,Ib,		"PSHUFL	%i,%x,%X",
[0x71]	RMOP,0,		optab660F71,
[0x72]	RMOP,0,		optab660F72,
[0x73]	RMOP,0,		optab660F73,
[0x7E]	RM,0,		"MOV%S	%X,%e",
[0x7F]	RM,0,		"MOVO	%X,%x",
[0xC4]	RM,Ib,		"PINSRW	%i,%e,%X",
[0xC5]	RMR,Ib,		"PEXTRW	%i,%X,%e",
[0xD4]	RM,0,		"PADDQ	%x,%X",
[0xD5]	RM,0,		"PMULLW	%x,%X",
[0xD6]	RM,0,		"MOVQ	%X,%x",
[0xE6]	RM,0,		"CVTTPD2PL	%x,%X",
[0xE7]	RM,0,		"MOVNTO	%X,%e",
[0xF7]	RM,0,		"MASKMOVOU	%x,%X",
};

static Optable optabF20F[256]=
{
[0x10]	RM,0,		"MOVSD	%x,%X",
[0x11]	RM,0,		"MOVSD	%X,%x",
[0x2A]	RM,0,		"CVTS%S2SD	%e,%X",
[0x2C]	RM,0,		"CVTTSD2S%S	%x,%r",
[0x2D]	RM,0,		"CVTSD2S%S	%x,%r",
[0x5A]	RM,0,		"CVTSD2SS	%x,%X",
[0x6F]	RM,0,		"MOVOU	%x,%X",
[0x70]	RM,Ib,		"PSHUFLW	%i,%x,%X",
[0x7F]	RM,0,		"MOVOU	%X,%x",
[0xD6]	RM,0,		"MOVQOZX	%M,%X",
[0xE6]	RM,0,		"CVTPD2PL	%x,%X",
};

static Optable optabF30F[256]=
{
[0x10]	RM,0,		"MOVSS	%x,%X",
[0x11]	RM,0,		"MOVSS	%X,%x",
[0x2A]	RM,0,		"CVTS%S2SS	%e,%X",
[0x2C]	RM,0,		"CVTTSS2S%S	%x,%r",
[0x2D]	RM,0,		"CVTSS2S%S	%x,%r",
[0x5A]	RM,0,		"CVTSS2SD	%x,%X",
[0x5B]	RM,0,		"CVTTPS2PL	%x,%X",
[0x6F]	RM,0,		"MOVOU	%x,%X",
[0x70]	RM,Ib,		"PSHUFHW	%i,%x,%X",
[0x7E]	RM,0,		"MOVQOZX	%x,%X",
[0x7F]	RM,0,		"MOVOU	%X,%x",
[0xD6]	RM,0,		"MOVQOZX	%m*,%X",
[0xE6]	RM,0,		"CVTPL2PD	%x,%X",
};

static Optable optab0F[256]=
{
[0x00]	RMOP,0,		optab0F00,
[0x01]	RMOP,0,		optab0F01,
[0x02]	RM,0,		"LAR	%e,%r",
[0x03]	RM,0,		"LSL	%e,%r",
[0x05]	0,0,		"SYSCALL",
[0x06]	0,0,		"CLTS",
[0x07]	0,0,		"SYSRET",
[0x08]	0,0,		"INVD",
[0x09]	0,0,		"WBINVD",
[0x0B]	0,0,		"UD2",
[0x0F]	RM,AUX,		optab0F0F,		/* 3DNow! */
[0x10]	RM,0,		"MOVU%s	%x,%X",
[0x11]	RM,0,		"MOVU%s	%X,%x",
[0x12]	RM,0,		"MOV[H]L%s	%x,%X",	/* TO DO: H if source is XMM */
[0x13]	RM,0,		"MOVL%s	%X,%e",
[0x14]	RM,0,		"UNPCKL%s	%x,%X",
[0x15]	RM,0,		"UNPCKH%s	%x,%X",
[0x16]	RM,0,		"MOV[L]H%s	%x,%X",	/* TO DO: L if source is XMM */
[0x17]	RM,0,		"MOVH%s	%X,%x",
[0x20]	RMR,0,		"MOVL	%C,%e",
[0x21]	RMR,0,		"MOVL	%D,%e",
[0x22]	RMR,0,		"MOVL	%e,%C",
[0x23]	RMR,0,		"MOVL	%e,%D",
[0x24]	RMR,0,		"MOVL	%T,%e",
[0x26]	RMR,0,		"MOVL	%e,%T",
[0x28]	RM,0,		"MOVA%s	%x,%X",
[0x29]	RM,0,		"MOVA%s	%X,%x",
[0x2A]	RM,0,		"CVTPL2%s	%m*,%X",
[0x2B]	RM,0,		"MOVNT%s	%X,%e",
[0x2C]	RM,0,		"CVTT%s2PL	%x,%M",
[0x2D]	RM,0,		"CVT%s2PL	%x,%M",
[0x2E]	RM,0,		"UCOMISS	%x,%X",
[0x2F]	RM,0,		"COMISS	%x,%X",
[0x30]	0,0,		"WRMSR",
[0x31]	0,0,		"RDTSC",
[0x32]	0,0,		"RDMSR",
[0x33]	0,0,		"RDPMC",
[0x42]	RM,0,		"CMOVC	%e,%r",		/* CF */
[0x43]	RM,0,		"CMOVNC	%e,%r",		/* ¬ CF */
[0x44]	RM,0,		"CMOVZ	%e,%r",		/* ZF */
[0x45]	RM,0,		"CMOVNZ	%e,%r",		/* ¬ ZF */
[0x46]	RM,0,		"CMOVBE	%e,%r",		/* CF ∨ ZF */
[0x47]	RM,0,		"CMOVA	%e,%r",		/* ¬CF ∧ ¬ZF */
[0x48]	RM,0,		"CMOVS	%e,%r",		/* SF */
[0x49]	RM,0,		"CMOVNS	%e,%r",		/* ¬ SF */
[0x4A]	RM,0,		"CMOVP	%e,%r",		/* PF */
[0x4B]	RM,0,		"CMOVNP	%e,%r",		/* ¬ PF */
[0x4C]	RM,0,		"CMOVLT	%e,%r",		/* LT ≡ OF ≠ SF */
[0x4D]	RM,0,		"CMOVGE	%e,%r",		/* GE ≡ ZF ∨ SF */
[0x4E]	RM,0,		"CMOVLE	%e,%r",		/* LE ≡ ZF ∨ LT */
[0x4F]	RM,0,		"CMOVGT	%e,%r",		/* GT ≡ ¬ZF ∧ GE */
[0x50]	RM,0,		"MOVMSK%s	%X,%r",	/* TO DO: check */
[0x51]	RM,0,		"SQRT%s	%x,%X",
[0x52]	RM,0,		"RSQRT%s	%x,%X",
[0x53]	RM,0,		"RCP%s	%x,%X",
[0x54]	RM,0,		"AND%s	%x,%X",
[0x55]	RM,0,		"ANDN%s	%x,%X",
[0x56]	RM,0,		"OR%s	%x,%X",		/* TO DO: S/D */
[0x57]	RM,0,		"XOR%s	%x,%X",		/* S/D */
[0x58]	RM,0,		"ADD%s	%x,%X",		/* S/P S/D */
[0x59]	RM,0,		"MUL%s	%x,%X",
[0x5A]	RM,0,		"CVTPS2PD	%x,%X",
[0x5B]	RM,0,		"CVTPL2PS	%x,%X",
[0x5C]	RM,0,		"SUB%s	%x,%X",
[0x5D]	RM,0,		"MIN%s	%x,%X",
[0x5E]	RM,0,		"DIV%s	%x,%X",		/* TO DO: S/P S/D */
[0x5F]	RM,0,		"MAX%s	%x,%X",
[0x60]	RM,0,		"PUNPCKLBW %m,%M",
[0x61]	RM,0,		"PUNPCKLWL %m,%M",
[0x62]	RM,0,		"PUNPCKLLQ %m,%M",
[0x63]	RM,0,		"PACKSSWB %m,%M",
[0x64]	RM,0,		"PCMPGTB %m,%M",
[0x65]	RM,0,		"PCMPGTW %m,%M",
[0x66]	RM,0,		"PCMPGTL %m,%M",
[0x67]	RM,0,		"PACKUSWB %m,%M",
[0x68]	RM,0,		"PUNPCKHBW %m,%M",
[0x69]	RM,0,		"PUNPCKHWL %m,%M",
[0x6A]	RM,0,		"PUNPCKHLQ %m,%M",
[0x6B]	RM,0,		"PACKSSLW %m,%M",
[0x6E]	RM,0,		"MOV%S %e,%M",
[0x6F]	RM,0,		"MOVQ %m,%M",
[0x70]	RM,Ib,		"PSHUFW	%i,%m,%M",
[0x74]	RM,0,		"PCMPEQB %m,%M",
[0x75]	RM,0,		"PCMPEQW %m,%M",
[0x76]	RM,0,		"PCMPEQL %m,%M",
[0x7E]	RM,0,		"MOV%S %M,%e",
[0x7F]	RM,0,		"MOVQ %M,%m",
[0xAE]	RMOP,0,		optab0FAE,
[0xAA]	0,0,		"RSM",
[0xB0]	RM,0,		"CMPXCHGB	%r,%e",
[0xB1]	RM,0,		"CMPXCHG%S	%r,%e",
[0xC0]	RMB,0,		"XADDB	%r,%e",
[0xC1]	RM,0,		"XADD%S	%r,%e",