mikepaul-LuaJIT/src/buildvm_peobj.c

/*
** LuaJIT VM builder: PE object emitter.
** Copyright (C) 2005-2009 Mike Pall. See Copyright Notice in luajit.h
**
** Only used for building on Windows, since we cannot assume the presence
** of a suitable assembler. The host and target byte order must match.
*/

#include "buildvm.h"
#include "lj_bc.h"

#if LJ_TARGET_X86ORX64

/* Context for PE object emitter. */
static char *strtab;
static size_t strtabofs;

/* -- PE object definitions ----------------------------------------------- */

/* PE header. */
typedef struct PEheader {
  uint16_t arch;
  uint16_t nsects;
  uint32_t time;
  uint32_t symtabofs;
  uint32_t nsyms;
  uint16_t opthdrsz;
  uint16_t flags;
} PEheader;

/* PE section. */
typedef struct PEsection {
  char name[8];
  uint32_t vsize;
  uint32_t vaddr;
  uint32_t size;
  uint32_t ofs;
  uint32_t relocofs;
  uint32_t lineofs;
  uint16_t nreloc;
  uint16_t nline;
  uint32_t flags;
} PEsection;

/* PE relocation. */
typedef struct PEreloc {
  uint32_t vaddr;
  uint32_t symidx;
  uint16_t type;
} PEreloc;

/* Cannot use sizeof, because it pads up to the max. alignment. */
#define PEOBJ_RELOC_SIZE	(4+4+2)

/* PE symbol table entry. */
typedef struct PEsym {
  union {
    char name[8];
    uint32_t nameref[2];
  } n;
  uint32_t value;
  int16_t sect;
  uint16_t type;
  uint8_t scl;
  uint8_t naux;
} PEsym;

/* PE symbol table auxiliary entry for a section. */
typedef struct PEsymaux {
  uint32_t size;
  uint16_t nreloc;
  uint16_t nline;
  uint32_t cksum;
  uint16_t assoc;
  uint8_t comdatsel;
  uint8_t unused[3];
} PEsymaux;

/* Cannot use sizeof, because it pads up to the max. alignment. */
#define PEOBJ_SYM_SIZE	(8+4+2+2+1+1)

/* PE object CPU specific defines. */
#if LJ_TARGET_X86
#define PEOBJ_ARCH_TARGET	0x014c
#define PEOBJ_RELOC_REL32	0x14  /* MS: REL32, GNU: DISP32. */
#define PEOBJ_RELOC_DIR32	0x06
#define PEOBJ_SYM_PREFIX	"_"
#elif LJ_TARGET_X64
#define PEOBJ_ARCH_TARGET	0x8664
#define PEOBJ_RELOC_REL32	0x04  /* MS: REL32, GNU: DISP32. */
#define PEOBJ_RELOC_DIR32	0x02
#define PEOBJ_SYM_PREFIX	""
#endif

/* Section numbers (0-based). */
enum {
  PEOBJ_SECT_ABS = -2,
  PEOBJ_SECT_UNDEF = -1,
  PEOBJ_SECT_TEXT,
  /* TODO: add .pdata/.xdata for x64. */
  PEOBJ_SECT_RDATA,
  PEOBJ_SECT_RDATA_Z,
  PEOBJ_NSECTIONS
};

/* Symbol types. */
#define PEOBJ_TYPE_NULL		0
#define PEOBJ_TYPE_FUNC		0x20

/* Symbol storage class. */
#define PEOBJ_SCL_EXTERN	2
#define PEOBJ_SCL_STATIC	3

/* -- PE object emitter --------------------------------------------------- */

/* Emit PE object symbol. */
static void emit_peobj_sym(BuildCtx *ctx, const char *name, uint32_t value,
			   int sect, int type, int scl)
{
  PEsym sym;
  size_t len = strlen(name);
  if (!strtab) {  /* Pass 1: only calculate string table length. */
    if (len > 8) strtabofs += len+1;
    return;
  }
  if (len <= 8) {
    memcpy(sym.n.name, name, len);
    memset(sym.n.name+len, 0, 8-len);
  } else {
    sym.n.nameref[0] = 0;
    sym.n.nameref[1] = strtabofs;
    memcpy(strtab + strtabofs, name, len);
    strtab[strtabofs+len] = 0;
    strtabofs += len+1;
  }
  sym.value = value;
  sym.sect = (int16_t)(sect+1);  /* 1-based section number. */
  sym.type = (uint16_t)type;
  sym.scl = (uint8_t)scl;
  sym.naux = 0;
  owrite(ctx, &sym, PEOBJ_SYM_SIZE);
}

/* Emit PE object section symbol. */
static void emit_peobj_sym_sect(BuildCtx *ctx, PEsection *pesect, int sect)
{
  PEsym sym;
  PEsymaux aux;
  if (!strtab) return;  /* Pass 1: no output. */
  memcpy(sym.n.name, pesect[sect].name, 8);
  sym.value = 0;
  sym.sect = (int16_t)(sect+1);  /* 1-based section number. */
  sym.type = PEOBJ_TYPE_NULL;
  sym.scl = PEOBJ_SCL_STATIC;
  sym.naux = 1;
  owrite(ctx, &sym, PEOBJ_SYM_SIZE);
  memset(&aux, 0, sizeof(PEsymaux));
  aux.size = pesect[sect].size;
  aux.nreloc = pesect[sect].nreloc;
  owrite(ctx, &aux, PEOBJ_SYM_SIZE);
}

#define emit_peobj_sym_func(ctx, name, ofs) \
  emit_peobj_sym(ctx, name, (uint32_t)(ofs), \
		 PEOBJ_SECT_TEXT, PEOBJ_TYPE_FUNC, PEOBJ_SCL_EXTERN)
#define emit_peobj_sym_rdata(ctx, name, ofs) \
  emit_peobj_sym(ctx, name, (uint32_t)(ofs), \
		 PEOBJ_SECT_RDATA, PEOBJ_TYPE_NULL, PEOBJ_SCL_EXTERN)

/* Emit Windows PE object file. */
void emit_peobj(BuildCtx *ctx)
{
  PEheader pehdr;
  PEsection pesect[PEOBJ_NSECTIONS];
  int nzsym, relocsyms;
  uint32_t sofs;
  int i;
  union { uint8_t b; uint32_t u; } host_endian;

  host_endian.u = 1;
  if (host_endian.b != LJ_ENDIAN_SELECT(1, 0)) {
    fprintf(stderr, "Error: different byte order for host and target\n");
    exit(1);
  }

  sofs = sizeof(PEheader) + PEOBJ_NSECTIONS*sizeof(PEsection);

  /* Fill in PE sections. */
  memset(&pesect, 0, PEOBJ_NSECTIONS*sizeof(PEsection));
  memcpy(pesect[PEOBJ_SECT_TEXT].name, ".text", sizeof(".text")-1);
  pesect[PEOBJ_SECT_TEXT].ofs = sofs;
  sofs += (pesect[PEOBJ_SECT_TEXT].size = (uint32_t)ctx->codesz);
  pesect[PEOBJ_SECT_TEXT].relocofs = sofs;
  sofs += (pesect[PEOBJ_SECT_TEXT].nreloc = (uint16_t)ctx->nreloc) * PEOBJ_RELOC_SIZE;
  /* Flags: 60 = read+execute, 50 = align16, 20 = code. */
  pesect[PEOBJ_SECT_TEXT].flags = 0x60500020;

  memcpy(pesect[PEOBJ_SECT_RDATA].name, ".rdata", sizeof(".rdata")-1);
  pesect[PEOBJ_SECT_RDATA].ofs = sofs;
  sofs += (pesect[PEOBJ_SECT_RDATA].size = ctx->npc*sizeof(uint16_t));
  /* Flags: 40 = read, 30 = align4, 40 = initialized data. */
  pesect[PEOBJ_SECT_RDATA].flags = 0x40300040;

  memcpy(pesect[PEOBJ_SECT_RDATA_Z].name, ".rdata$Z", sizeof(".rdata$Z")-1);
  pesect[PEOBJ_SECT_RDATA_Z].ofs = sofs;
  sofs += (pesect[PEOBJ_SECT_RDATA_Z].size = (uint32_t)strlen(ctx->dasm_ident)+1);
  /* Flags: 40 = read, 30 = align4, 40 = initialized data. */
  pesect[PEOBJ_SECT_RDATA_Z].flags = 0x40300040;

  /* Fill in PE header. */
  pehdr.arch = PEOBJ_ARCH_TARGET;
  pehdr.nsects = PEOBJ_NSECTIONS;
  pehdr.time = 0;  /* Timestamp is optional. */
  pehdr.symtabofs = sofs;
  pehdr.opthdrsz = 0;
  pehdr.flags = 0;

  /* Compute the size of the symbol table:
  ** @feat.00 + nsections*2
  ** + asm_start + (nsyms-nzsym) + op_ofs
  ** + relocsyms
  */
  /* Skip _Z syms. */
  for (nzsym = 0; ctx->sym_ofs[ctx->perm[nzsym]] < 0; nzsym++) ;
  for (relocsyms = 0; ctx->extnames[relocsyms]; relocsyms++) ;
  pehdr.nsyms = 1+PEOBJ_NSECTIONS*2 + 1+(ctx->nsym-nzsym)+1 + relocsyms;

  /* Write PE object header and all sections. */
  owrite(ctx, &pehdr, sizeof(PEheader));
  owrite(ctx, &pesect, sizeof(PEsection)*PEOBJ_NSECTIONS);

  /* Write .text section. */
  owrite(ctx, ctx->code, ctx->codesz);
  for (i = 0; i < ctx->nreloc; i++) {
    PEreloc reloc;
    reloc.vaddr = (uint32_t)ctx->reloc[i].ofs;
    reloc.symidx = 1+2+ctx->reloc[i].sym;  /* Reloc syms are after .text sym. */
    reloc.type = ctx->reloc[i].type ? PEOBJ_RELOC_REL32 : PEOBJ_RELOC_DIR32;
    owrite(ctx, &reloc, PEOBJ_RELOC_SIZE);
  }

  /* Write .rdata section. */
  for (i = 0; i < ctx->npc; i++) {
    uint16_t pcofs = (uint16_t)ctx->sym_ofs[i];
    owrite(ctx, &pcofs, 2);
  }

  /* Write .rdata$Z section. */
  owrite(ctx, ctx->dasm_ident, strlen(ctx->dasm_ident)+1);

  /* Write symbol table. */
  strtab = NULL;  /* 1st pass: collect string sizes. */
  for (;;) {
    char name[80];

    strtabofs = 4;
    /* Mark as SafeSEH compliant. */
    emit_peobj_sym(ctx, "@feat.00", 1,
		   PEOBJ_SECT_ABS, PEOBJ_TYPE_NULL, PEOBJ_SCL_STATIC);

    emit_peobj_sym_sect(ctx, pesect, PEOBJ_SECT_TEXT);
    for (i = 0; ctx->extnames[i]; i++) {
      sprintf(name, PEOBJ_SYM_PREFIX "%s", ctx->extnames[i]);
      emit_peobj_sym(ctx, name, 0,
		     PEOBJ_SECT_UNDEF, PEOBJ_TYPE_FUNC, PEOBJ_SCL_EXTERN);
    }
    emit_peobj_sym(ctx, PEOBJ_SYM_PREFIX LABEL_ASM_BEGIN, 0,
		   PEOBJ_SECT_TEXT, PEOBJ_TYPE_NULL, PEOBJ_SCL_EXTERN);
    for (i = nzsym; i < ctx->nsym; i++) {
      int pi = ctx->perm[i];
      if (pi >= ctx->npc) {
	sprintf(name, PEOBJ_SYM_PREFIX LABEL_PREFIX "%s",
		ctx->globnames[pi-ctx->npc]);
	emit_peobj_sym_func(ctx, name, ctx->sym_ofs[pi]);
#if LJ_HASJIT
      } else {
#else
      } else if (!(pi == BC_JFORI || pi == BC_JFORL || pi == BC_JITERL ||
		   pi == BC_JLOOP || pi == BC_IFORL || pi == BC_IITERL ||
		   pi == BC_ILOOP)) {
#endif
	sprintf(name, PEOBJ_SYM_PREFIX LABEL_PREFIX_BC "%s",
		bc_names[pi]);
	emit_peobj_sym_func(ctx, name, ctx->sym_ofs[pi]);
      }
    }

    emit_peobj_sym_sect(ctx, pesect, PEOBJ_SECT_RDATA);
    emit_peobj_sym_rdata(ctx, PEOBJ_SYM_PREFIX LABEL_OP_OFS, 0);

    emit_peobj_sym_sect(ctx, pesect, PEOBJ_SECT_RDATA_Z);

    if (strtab)
      break;
    /* 2nd pass: alloc strtab, write syms and copy strings. */
    strtab = (char *)malloc(strtabofs);
    *(uint32_t *)strtab = strtabofs;
  }

  /* Write string table. */
  owrite(ctx, strtab, strtabofs);
}

#endif