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/*
** LuaJIT VM builder: Assembler source code emitter.
** Copyright (C) 2005-2022 Mike Pall. See Copyright Notice in luajit.h
*/
#include "buildvm.h"
#include "lj_bc.h"
/* ------------------------------------------------------------------------ */
#if LJ_TARGET_X86ORX64
/* Emit bytes piecewise as assembler text. */
static void emit_asm_bytes(BuildCtx *ctx, uint8_t *p, int n)
{
int i;
for (i = 0; i < n; i++) {
if ((i & 15) == 0)
fprintf(ctx->fp, "\t.byte %d", p[i]);
else
fprintf(ctx->fp, ",%d", p[i]);
if ((i & 15) == 15) putc('\n', ctx->fp);
}
if ((n & 15) != 0) putc('\n', ctx->fp);
}
/* Emit relocation */
static void emit_asm_reloc(BuildCtx *ctx, int type, const char *sym)
{
switch (ctx->mode) {
case BUILD_elfasm:
if (type)
fprintf(ctx->fp, "\t.long %s-.-4\n", sym);
else
fprintf(ctx->fp, "\t.long %s\n", sym);
break;
case BUILD_coffasm:
fprintf(ctx->fp, "\t.def %s; .scl 3; .type 32; .endef\n", sym);
if (type)
fprintf(ctx->fp, "\t.long %s-.-4\n", sym);
else
fprintf(ctx->fp, "\t.long %s\n", sym);
break;
default: /* BUILD_machasm for relative relocations handled below. */
fprintf(ctx->fp, "\t.long %s\n", sym);
break;
}
}
static const char *const jccnames[] = {
"jo", "jno", "jb", "jnb", "jz", "jnz", "jbe", "ja",
"js", "jns", "jpe", "jpo", "jl", "jge", "jle", "jg"
};
/* Emit x86/x64 text relocations. */
static void emit_asm_reloc_text(BuildCtx *ctx, uint8_t *cp, int n,
const char *sym)
{
const char *opname = NULL;
if (--n < 0) goto err;
if (cp[n] == 0xe8) {
opname = "call";
} else if (cp[n] == 0xe9) {
opname = "jmp";
} else if (cp[n] >= 0x80 && cp[n] <= 0x8f && n > 0 && cp[n-1] == 0x0f) {
opname = jccnames[cp[n]-0x80];
n--;
} else {
err:
fprintf(stderr, "Error: unsupported opcode for %s symbol relocation.\n",
sym);
exit(1);
}
emit_asm_bytes(ctx, cp, n);
if (strncmp(sym+(*sym == '_'), LABEL_PREFIX, sizeof(LABEL_PREFIX)-1)) {
/* Various fixups for external symbols outside of our binary. */
if (ctx->mode == BUILD_elfasm) {
if (LJ_32)
fprintf(ctx->fp, "#if __PIC__\n\t%s lj_wrap_%s\n#else\n", opname, sym);
fprintf(ctx->fp, "\t%s %s@PLT\n", opname, sym);
if (LJ_32)
fprintf(ctx->fp, "#endif\n");
return;
} else if (LJ_32 && ctx->mode == BUILD_machasm) {
fprintf(ctx->fp, "\t%s L%s$stub\n", opname, sym);
return;
}
}
fprintf(ctx->fp, "\t%s %s\n", opname, sym);
}
#else
/* Emit words piecewise as assembler text. */
static void emit_asm_words(BuildCtx *ctx, uint8_t *p, int n)
{
int i;
for (i = 0; i < n; i += 4) {
uint32_t ins = *(uint32_t *)(p+i);
#if LJ_TARGET_ARM64 && LJ_BE
ins = lj_bswap(ins); /* ARM64 instructions are always little-endian. */
#endif
if ((i & 15) == 0)
fprintf(ctx->fp, "\t.long 0x%08x", ins);
else
fprintf(ctx->fp, ",0x%08x", ins);
if ((i & 15) == 12) putc('\n', ctx->fp);
}
if ((n & 15) != 0) putc('\n', ctx->fp);
}
/* Emit relocation as part of an instruction. */
static void emit_asm_wordreloc(BuildCtx *ctx, uint8_t *p, int n,
const char *sym)
{
uint32_t ins;
emit_asm_words(ctx, p, n-4);
ins = *(uint32_t *)(p+n-4);
#if LJ_TARGET_ARM
if ((ins & 0xff000000u) == 0xfa000000u) {
fprintf(ctx->fp, "\tblx %s\n", sym);
} else if ((ins & 0x0e000000u) == 0x0a000000u) {
fprintf(ctx->fp, "\t%s%.2s %s\n", (ins & 0x01000000u) ? "bl" : "b",
&"eqnecsccmiplvsvchilsgeltgtle"[2*(ins >> 28)], sym);
} else {
fprintf(stderr,
"Error: unsupported opcode %08x for %s symbol relocation.\n",
ins, sym);
exit(1);
}
#elif LJ_TARGET_ARM64
if ((ins >> 26) == 0x25u) {
fprintf(ctx->fp, "\tbl %s\n", sym);
} else {
fprintf(stderr,
"Error: unsupported opcode %08x for %s symbol relocation.\n",
ins, sym);
exit(1);
}
#elif LJ_TARGET_PPC
#if LJ_TARGET_PS3
#define TOCPREFIX "."
#else
#define TOCPREFIX ""
#endif
if ((ins >> 26) == 16) {
fprintf(ctx->fp, "\t%s %d, %d, " TOCPREFIX "%s\n",
(ins & 1) ? "bcl" : "bc", (ins >> 21) & 31, (ins >> 16) & 31, sym);
} else if ((ins >> 26) == 18) {
fprintf(ctx->fp, "\t%s " TOCPREFIX "%s\n", (ins & 1) ? "bl" : "b", sym);
} else {
fprintf(stderr,
"Error: unsupported opcode %08x for %s symbol relocation.\n",
ins, sym);
exit(1);
}
#elif LJ_TARGET_MIPS
fprintf(stderr,
"Error: unsupported opcode %08x for %s symbol relocation.\n",
ins, sym);
exit(1);
#else
#error "missing relocation support for this architecture"
#endif
}
#endif
#if LJ_TARGET_ARM
#define ELFASM_PX "%%"
#else
#define ELFASM_PX "@"
#endif
/* Emit an assembler label. */
static void emit_asm_label(BuildCtx *ctx, const char *name, int size, int isfunc)
{
switch (ctx->mode) {
case BUILD_elfasm:
#if LJ_TARGET_PS3
if (!strncmp(name, "lj_vm_", 6) &&
strcmp(name, ctx->beginsym) &&
!strstr(name, "hook")) {
fprintf(ctx->fp,
"\n\t.globl %s\n"
"\t.section \".opd\",\"aw\"\n"
"%s:\n"
"\t.long .%s,.TOC.@tocbase32\n"
"\t.size %s,8\n"
"\t.previous\n"
"\t.globl .%s\n"
"\t.hidden .%s\n"
"\t.type .%s, " ELFASM_PX "function\n"
"\t.size .%s, %d\n"
".%s:\n",
name, name, name, name, name, name, name, name, size, name);
break;
}
#endif
fprintf(ctx->fp,
"\n\t.globl %s\n"
"\t.hidden %s\n"
"\t.type %s, " ELFASM_PX "%s\n"
"\t.size %s, %d\n"
"%s:\n",
name, name, name, isfunc ? "function" : "object", name, size, name);
break;
case BUILD_coffasm:
fprintf(ctx->fp, "\n\t.globl %s\n", name);
if (isfunc)
fprintf(ctx->fp, "\t.def %s; .scl 3; .type 32; .endef\n", name);
fprintf(ctx->fp, "%s:\n", name);
break;
case BUILD_machasm:
fprintf(ctx->fp,
"\n\t.private_extern %s\n"
"\t.no_dead_strip %s\n"
"%s:\n", name, name, name);
break;
default:
break;
}
}
/* Emit alignment. */
static void emit_asm_align(BuildCtx *ctx, int bits)
{
switch (ctx->mode) {
case BUILD_elfasm:
case BUILD_coffasm:
fprintf(ctx->fp, "\t.p2align %d\n", bits);
break;
case BUILD_machasm:
fprintf(ctx->fp, "\t.align %d\n", bits);
break;
default:
break;
}
}
/* ------------------------------------------------------------------------ */
/* Emit assembler source code. */
void emit_asm(BuildCtx *ctx)
{
int i, rel;
fprintf(ctx->fp, "\t.file \"buildvm_%s.dasc\"\n", ctx->dasm_arch);
fprintf(ctx->fp, "\t.text\n");
emit_asm_align(ctx, 4);
#if LJ_TARGET_PS3
emit_asm_label(ctx, ctx->beginsym, ctx->codesz, 0);
#else
emit_asm_label(ctx, ctx->beginsym, 0, 0);
#endif
if (ctx->mode != BUILD_machasm)
fprintf(ctx->fp, ".Lbegin:\n");
#if LJ_TARGET_ARM && defined(__GNUC__) && !LJ_NO_UNWIND
/* This should really be moved into buildvm_arm.dasc. */
#if LJ_ARCH_HASFPU
fprintf(ctx->fp,
".fnstart\n"
".save {r5, r6, r7, r8, r9, r10, r11, lr}\n"
".vsave {d8-d15}\n"
".save {r4}\n"
".pad #28\n");
#else
fprintf(ctx->fp,
".fnstart\n"
".save {r4, r5, r6, r7, r8, r9, r10, r11, lr}\n"
".pad #28\n");
#endif
#endif
#if LJ_TARGET_MIPS
fprintf(ctx->fp, ".set nomips16\n.abicalls\n.set noreorder\n.set nomacro\n");
#endif
for (i = rel = 0; i < ctx->nsym; i++) {
int32_t ofs = ctx->sym[i].ofs;
int32_t next = ctx->sym[i+1].ofs;
#if LJ_TARGET_ARM && defined(__GNUC__) && !LJ_NO_UNWIND && LJ_HASFFI
if (!strcmp(ctx->sym[i].name, "lj_vm_ffi_call"))
fprintf(ctx->fp,
".globl lj_err_unwind_arm\n"
".personality lj_err_unwind_arm\n"
".fnend\n"
".fnstart\n"
".save {r4, r5, r11, lr}\n"
".setfp r11, sp\n");
#endif
emit_asm_label(ctx, ctx->sym[i].name, next - ofs, 1);
while (rel < ctx->nreloc && ctx->reloc[rel].ofs <= next) {
BuildReloc *r = &ctx->reloc[rel];
int n = r->ofs - ofs;
#if LJ_TARGET_X86ORX64
if (r->type != 0 &&
(ctx->mode == BUILD_elfasm || ctx->mode == BUILD_machasm)) {
emit_asm_reloc_text(ctx, ctx->code+ofs, n, ctx->relocsym[r->sym]);
} else {
emit_asm_bytes(ctx, ctx->code+ofs, n);
emit_asm_reloc(ctx, r->type, ctx->relocsym[r->sym]);
}
ofs += n+4;
#else
emit_asm_wordreloc(ctx, ctx->code+ofs, n, ctx->relocsym[r->sym]);
ofs += n;
#endif
rel++;
}
#if LJ_TARGET_X86ORX64
emit_asm_bytes(ctx, ctx->code+ofs, next-ofs);
#else
emit_asm_words(ctx, ctx->code+ofs, next-ofs);
#endif
}
#if LJ_TARGET_ARM && defined(__GNUC__) && !LJ_NO_UNWIND
fprintf(ctx->fp,
#if !LJ_HASFFI
".globl lj_err_unwind_arm\n"
".personality lj_err_unwind_arm\n"
#endif
".fnend\n");
#endif
fprintf(ctx->fp, "\n");
switch (ctx->mode) {
case BUILD_elfasm:
#if !(LJ_TARGET_PS3 || LJ_TARGET_PSVITA)
fprintf(ctx->fp, "\t.section .note.GNU-stack,\"\"," ELFASM_PX "progbits\n");
#endif
#if LJ_TARGET_PPC && !LJ_TARGET_PS3 && !LJ_ABI_SOFTFP
/* Hard-float ABI. */
fprintf(ctx->fp, "\t.gnu_attribute 4, 1\n");
#endif
/* fallthrough */
case BUILD_coffasm:
fprintf(ctx->fp, "\t.ident \"%s\"\n", ctx->dasm_ident);
break;
case BUILD_machasm:
fprintf(ctx->fp,
"\t.cstring\n"
"\t.ascii \"%s\\0\"\n", ctx->dasm_ident);
break;
default:
break;
}
fprintf(ctx->fp, "\n");
}
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