dyngen.c

qemu性能直逼VMware的仿真器QEMU 的模擬速度約為實機的 25％；約為 Bochs 的 60 倍。Plex86、User-Mode-Linux、VMware 和 Virtual PC 則比

            }
            fprintf(outfile, ";\n");
        }
#if defined(HOST_IA64)
        fprintf(outfile, "    extern char %s;\n", name);
#else
        fprintf(outfile, "    extern void %s();\n", name);
#endif

        for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) {
            host_ulong offset = get_rel_offset(rel);
            if (offset >= start_offset &&
                offset < start_offset + (p_end - p_start)) {
                sym_name = get_rel_sym_name(rel);
                if(!sym_name)
                    continue;
                if (*sym_name && 
                    !strstart(sym_name, "__op_param", NULL) &&
                    !strstart(sym_name, "__op_jmp", NULL) &&
                    !strstart(sym_name, "__op_gen_label", NULL)) {
#if defined(HOST_SPARC)
		    if (sym_name[0] == '.') {
			fprintf(outfile,
				"extern char __dot_%s __asm__(\"%s\");\n",
				sym_name+1, sym_name);
			continue;
		    }
#endif
#if defined(__APPLE__)
/* set __attribute((unused)) on darwin because we wan't to avoid warning when we don't use the symbol */
                    fprintf(outfile, "extern char %s __attribute__((unused));\n", sym_name);
#elif defined(HOST_IA64)
			if (ELF64_R_TYPE(rel->r_info) != R_IA64_PCREL21B)
				/*
				 * PCREL21 br.call targets generally
				 * are out of range and need to go
				 * through an "import stub".
				 */
				fprintf(outfile, "    extern char %s;\n",
					sym_name);
#else
                    fprintf(outfile, "extern char %s;\n", sym_name);
#endif
                }
            }
        }

        fprintf(outfile, "    memcpy(gen_code_ptr, (void *)((char *)&%s+%d), %d);\n",
					name, (int)(start_offset - offset), copy_size);

        /* emit code offset information */
        {
            EXE_SYM *sym;
            const char *sym_name, *p;
            unsigned long val;
            int n;

            for(i = 0, sym = symtab; i < nb_syms; i++, sym++) {
                sym_name = get_sym_name(sym);
                if (strstart(sym_name, "__op_label", &p)) {
                    uint8_t *ptr;
                    unsigned long offset;
                    
                    /* test if the variable refers to a label inside
                       the code we are generating */
#ifdef CONFIG_FORMAT_COFF
                    if (sym->st_shndx == text_shndx) {
                        ptr = sdata[coff_text_shndx];
                    } else if (sym->st_shndx == data_shndx) {
                        ptr = sdata[coff_data_shndx];
                    } else {
                        ptr = NULL;
                    }
#elif defined(CONFIG_FORMAT_MACH)
                    if(!sym->n_sect)
                        continue;
                    ptr = sdata[sym->n_sect-1];
#else
                    ptr = sdata[sym->st_shndx];
#endif
                    if (!ptr)
                        error("__op_labelN in invalid section");
                    offset = sym->st_value;
#ifdef CONFIG_FORMAT_MACH
                    offset -= section_hdr[sym->n_sect-1].addr;
#endif
                    val = *(unsigned long *)(ptr + offset);
#ifdef ELF_USES_RELOCA
                    {
                        int reloc_shndx, nb_relocs1, j;

                        /* try to find a matching relocation */
                        reloc_shndx = find_reloc(sym->st_shndx);
                        if (reloc_shndx) {
                            nb_relocs1 = shdr[reloc_shndx].sh_size / 
                                shdr[reloc_shndx].sh_entsize;
                            rel = (ELF_RELOC *)sdata[reloc_shndx];
                            for(j = 0; j < nb_relocs1; j++) {
                                if (rel->r_offset == offset) {
				    val = rel->r_addend;
                                    break;
                                }
				rel++;
                            }
                        }
                    }
#endif                    
                    if (val >= start_offset && val <= start_offset + copy_size) {
                        n = strtol(p, NULL, 10);
                        fprintf(outfile, "    label_offsets[%d] = %ld + (gen_code_ptr - gen_code_buf);\n", n, (long)(val - start_offset));
                    }
                }
            }
        }

        /* load parameres in variables */
        for(i = 0; i < nb_args; i++) {
            fprintf(outfile, "    param%d = *opparam_ptr++;\n", i + 1);
        }

        /* patch relocations */
#if defined(HOST_I386)
            {
                char name[256];
                int type;
                int addend;
                int reloc_offset;
                for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) {
                if (rel->r_offset >= start_offset &&
		    rel->r_offset < start_offset + copy_size) {
                    sym_name = get_rel_sym_name(rel);
                    if (!sym_name)
                        continue;
                    reloc_offset = rel->r_offset - start_offset;
                    if (strstart(sym_name, "__op_jmp", &p)) {
                        int n;
                        n = strtol(p, NULL, 10);
                        /* __op_jmp relocations are done at
                           runtime to do translated block
                           chaining: the offset of the instruction
                           needs to be stored */
                        fprintf(outfile, "    jmp_offsets[%d] = %d + (gen_code_ptr - gen_code_buf);\n",
                                n, reloc_offset);
                        continue;
                    }

                    get_reloc_expr(name, sizeof(name), sym_name);
                    addend = get32((uint32_t *)(text + rel->r_offset));
#ifdef CONFIG_FORMAT_ELF
                    type = ELF32_R_TYPE(rel->r_info);
                    switch(type) {
                    case R_386_32:
                        fprintf(outfile, "    *(uint32_t *)(gen_code_ptr + %d) = %s + %d;\n", 
                                reloc_offset, name, addend);
                        break;
                    case R_386_PC32:
                        fprintf(outfile, "    *(uint32_t *)(gen_code_ptr + %d) = %s - (long)(gen_code_ptr + %d) + %d;\n", 
                                reloc_offset, name, reloc_offset, addend);
                        break;
                    default:
                        error("unsupported i386 relocation (%d)", type);
                    }
#elif defined(CONFIG_FORMAT_COFF)
                    {
                        char *temp_name;
                        int j;
                        EXE_SYM *sym;
                        temp_name = get_sym_name(symtab + *(uint32_t *)(rel->r_reloc->r_symndx));
                        if (!strcmp(temp_name, ".data")) {
                            for (j = 0, sym = symtab; j < nb_syms; j++, sym++) {
                                if (strstart(sym->st_name, sym_name, NULL)) {
                                    addend -= sym->st_value;
                                }
                            }
                        }
                    }
                    type = rel->r_type;
                    switch(type) {
                    case DIR32:
                        fprintf(outfile, "    *(uint32_t *)(gen_code_ptr + %d) = %s + %d;\n", 
                                reloc_offset, name, addend);
                        break;
                    case DISP32:
                        fprintf(outfile, "    *(uint32_t *)(gen_code_ptr + %d) = %s - (long)(gen_code_ptr + %d) + %d -4;\n", 
                                reloc_offset, name, reloc_offset, addend);
                        break;
                    default:
                        error("unsupported i386 relocation (%d)", type);
                    }
#else
#error unsupport object format
#endif
                }
                }
            }
#elif defined(HOST_X86_64)
            {
                char name[256];
                int type;
                int addend;
                int reloc_offset;
                for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) {
                if (rel->r_offset >= start_offset &&
		    rel->r_offset < start_offset + copy_size) {
                    sym_name = strtab + symtab[ELFW(R_SYM)(rel->r_info)].st_name;
                    get_reloc_expr(name, sizeof(name), sym_name);
                    type = ELF32_R_TYPE(rel->r_info);
                    addend = rel->r_addend;
                    reloc_offset = rel->r_offset - start_offset;
                    switch(type) {
                    case R_X86_64_32:
                        fprintf(outfile, "    *(uint32_t *)(gen_code_ptr + %d) = (uint32_t)%s + %d;\n", 
                                reloc_offset, name, addend);
                        break;
                    case R_X86_64_32S:
                        fprintf(outfile, "    *(uint32_t *)(gen_code_ptr + %d) = (int32_t)%s + %d;\n", 
                                reloc_offset, name, addend);
                        break;
                    case R_X86_64_PC32:
                        fprintf(outfile, "    *(uint32_t *)(gen_code_ptr + %d) = %s - (long)(gen_code_ptr + %d) + %d;\n", 
                                reloc_offset, name, reloc_offset, addend);
                        break;
                    default:
                        error("unsupported X86_64 relocation (%d)", type);
                    }
                }
                }
            }
#elif defined(HOST_PPC)
            {
#ifdef CONFIG_FORMAT_ELF
                char name[256];
                int type;
                int addend;
                int reloc_offset;
                for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) {
                    if (rel->r_offset >= start_offset &&
			rel->r_offset < start_offset + copy_size) {
                        sym_name = strtab + symtab[ELFW(R_SYM)(rel->r_info)].st_name;
                        reloc_offset = rel->r_offset - start_offset;
                        if (strstart(sym_name, "__op_jmp", &p)) {
                            int n;
                            n = strtol(p, NULL, 10);
                            /* __op_jmp relocations are done at
                               runtime to do translated block
                               chaining: the offset of the instruction
                               needs to be stored */
                            fprintf(outfile, "    jmp_offsets[%d] = %d + (gen_code_ptr - gen_code_buf);\n",
                                    n, reloc_offset);
                            continue;
                        }
                        
                        get_reloc_expr(name, sizeof(name), sym_name);
                        type = ELF32_R_TYPE(rel->r_info);
                        addend = rel->r_addend;
                        switch(type) {
                        case R_PPC_ADDR32:
                            fprintf(outfile, "    *(uint32_t *)(gen_code_ptr + %d) = %s + %d;\n", 
                                    reloc_offset, name, addend);
                            break;
                        case R_PPC_ADDR16_LO:
                            fprintf(outfile, "    *(uint16_t *)(gen_code_ptr + %d) = (%s + %d);\n", 
                                    reloc_offset, name, addend);
                            break;
                        case R_PPC_ADDR16_HI:
                            fprintf(outfile, "    *(uint16_t *)(gen_code_ptr + %d) = (%s + %d) >> 16;\n", 
                                    reloc_offset, name, addend);
                            break;
                        case R_PPC_ADDR16_HA:
                            fprintf(outfile, "    *(uint16_t *)(gen_code_ptr + %d) = (%s + %d + 0x8000) >> 16;\n", 
                                    reloc_offset, name, addend);
                            break;
                        case R_PPC_REL24:
                            /* warning: must be at 32 MB distancy */
                            fprintf(outfile, "    *(uint32_t *)(gen_code_ptr + %d) = (*(uint32_t *)(gen_code_ptr + %d) & ~0x03fffffc) | ((%s - (long)(gen_code_ptr + %d) + %d) & 0x03fffffc);\n", 
                                    reloc_offset, reloc_offset, name, reloc_offset, addend);
                            break;
                        default:
                            error("unsupported powerpc relocation (%d)", type);
                        }
                    }
                }
#elif defined(CONFIG_FORMAT_MACH)
				struct scattered_relocation_info *scarel;
				struct relocation_info * rel;
				char final_sym_name[256];
				const char *sym_name;
				const char *p;
				int slide, sslide;
				int i;
	
				for(i = 0, rel = relocs; i < nb_relocs; i++, rel++) {
					unsigned int offset, length, value = 0;
					unsigned int type, pcrel, isym = 0;
					unsigned int usesym = 0;
				
					if(R_SCATTERED & rel->r_address) {
						scarel = (struct scattered_relocation_info*)rel;
						offset = (unsigned int)scarel->r_address;
						length = scarel->r_length;
						pcrel = scarel->r_pcrel;
						type = scarel->r_type;
						value = scarel->r_value;
					} else {
						value = isym = rel->r_symbolnum;
						usesym = (rel->r_extern);
						offset = rel->r_address;
						length = rel->r_length;
						pcrel = rel->r_pcrel;
						type = rel->r_type;
					}
				
					slide = offset - start_offset;
		
					if (!(offset >= start_offset && offset < start_offset + size)) 
						continue;  /* not in our range */

					sym_name = get_reloc_name(rel, &sslide);
					
					if(usesym && symtab[isym].n_type & N_STAB)
						continue; /* don't handle STAB (debug sym) */
					
					if (sym_name && strstart(sym_name, "__op_jmp", &p)) {
						int n;
						n = strtol(p, NULL, 10);
						fprintf(outfile, "    jmp_offsets[%d] = %d + (gen_code_ptr - gen_code_buf);\n",
							n, slide);
						continue; /* Nothing more to do */
					}
					
					if(!sym_name)
					{
						fprintf(outfile, "/* #warning relocation not handled in %s (value 0x%x, %s, offset 0x%x, length 0x%x, %s, type 0x%x) */\n",
						           name, value, usesym ? "use sym" : "don't use sym", offset, length, pcrel ? "pcrel":"", type);
						continue; /* dunno how to handle without final_sym_name */
					}
													   
                                        get_reloc_expr(final_sym_name, sizeof(final_sym_name), 
                                                       sym_name);
					switch(type) {
					case PPC_RELOC_BR24:
					    if (!strstart(sym_name,"__op_gen_label",&p)) {
    						fprintf(outfile, "{\n");
    						fprintf(outfile, "    uint32_t imm = *(uint32_t *)(gen_code_ptr + %d) & 0x3fffffc;\n", slide);
    						fprintf(outfile, "    *(uint32_t *)(gen_code_ptr + %d) = (*(uint32_t *)(gen_code_ptr + %d) & ~0x03fffffc) | ((imm + ((long)%s - (long)gen_code_ptr) + %d) & 0x03fffffc);\n", 
											slide, slide, name, sslide );
    						fprintf(outfile, "}\n");
    					} else {
							fprintf(outfile, "    *(uint32_t *)(gen_code_ptr + %d) = (*(uint32_t *)(gen_code_ptr + %d) & ~0x03fffffc) | (((long)%s - (long)gen_code_ptr - %d) & 0x03fffffc);\n",
											slide, slide, final_sym_name, slide);
    					}
						break;
					case PPC_RELOC_HI16:
						fprintf(outfile, "    *(uint16_t *)(gen_code_ptr + %d + 2) = (%s + %d) >> 16;\n", 
							slide, final_sym_name, sslide);
						break;
					case PPC_RELOC_LO16:
						fprintf(outfile, "    *(uint16_t *)(gen_code_ptr + %d + 2) = (%s + %d);\n", 
					slide, final_sym_name, sslide);
                            break;
					case PPC_RELOC_HA16:
						fprintf(outfile, "    *(uint16_t *)(gen_code_ptr + %d + 2) = (%s + %d + 0x8000) >> 16;\n", 
							slide, final_sym_name, sslide);
						break;
				default:
					error("unsupported powerpc relocation (%d)", type);
				}
			}
#else
#error unsupport object format
#endif
            }
#elif defined(HOST_S390)
            {
                char name[256];
                int type;
                int addend;
                int reloc_offset;
                for(i = 0, rel = relocs;i < nb_relocs; i++, rel++) {
                    if (rel->r_offset >= start_offset &&
			rel->r_offset < start_offset + copy_size) {
                        sym_name = strtab + symtab[ELFW(R_SYM)(rel->r_info)].st_name;
                        get_reloc_expr(name, sizeof(name), sym_name);
                        type = ELF32_R_TYPE(rel->r_info);
                        addend = rel->r_addend;
                        reloc_offset = rel->r_offset - start_offset;
                        switch(type) {
                        case R_390_32:
                            fprintf(outfile, "    *(uint32_t *)(gen_code_ptr + %d) = %s + %d;\n", 
                                    reloc_offset, name, addend);
                            break;
                        case R_390_16:
                            fprintf(outfile, "    *(uint16_t *)(gen_code_ptr + %d) = %s + %d;\n", 
                                    reloc_offset, name, addend);
                            break;
                        case R_390_8:
                            fprintf(outfile, "    *(uint8_t *)(gen_code_ptr + %d) = %s + %d;\n", 
                                    reloc_offset, name, addend);
                            break;
                        default:
                            error("unsupported s390 relocation (%d)", type);
                        }
                    }
                }
            }
#elif defined(HOST_ALPHA)
            {
                for (i = 0, rel = relocs; i < nb_relocs; i++, rel++) {
		    if (rel->r_offset >= start_offset && rel->r_offset < start_offset + copy_size) {
			int type;
                        long reloc_offset;

			type = ELF64_R_TYPE(rel->r_info);
			sym_name = strtab + symtab[ELF64_R_SYM(rel->r_info)].st_name;
                        reloc_offset = rel->r_offset - start_offset;
			switch (type) {
			case R_ALPHA_GPDISP:
			    /* The gp is just 32 bit, and never changes, so it's easiest