/* outelf.c output routines for the Netwide Assembler to produce * ELF32 (i386 of course) object file format * * The Netwide Assembler is copyright (C) 1996 Simon Tatham and * Julian Hall. All rights reserved. The software is * redistributable under the licence given in the file "Licence" * distributed in the NASM archive. */ #include "compiler.h" #include #include #include #include #include #include "nasm.h" #include "nasmlib.h" #include "stdscan.h" #include "outform.h" #ifdef OF_ELF32 /* * Relocation types. */ enum reloc_type { R_386_32 = 1, /* ordinary absolute relocation */ R_386_PC32 = 2, /* PC-relative relocation */ R_386_GOT32 = 3, /* an offset into GOT */ R_386_PLT32 = 4, /* a PC-relative offset into PLT */ R_386_COPY = 5, /* ??? */ R_386_GLOB_DAT = 6, /* ??? */ R_386_JUMP_SLOT = 7, /* ??? */ R_386_RELATIVE = 8, /* ??? */ R_386_GOTOFF = 9, /* an offset from GOT base */ R_386_GOTPC = 10, /* a PC-relative offset _to_ GOT */ /* These are GNU extensions, but useful */ R_386_16 = 20, /* A 16-bit absolute relocation */ R_386_PC16 = 21, /* A 16-bit PC-relative relocation */ R_386_8 = 22, /* An 8-bit absolute relocation */ R_386_PC8 = 23 /* An 8-bit PC-relative relocation */ }; struct Reloc { struct Reloc *next; int32_t address; /* relative to _start_ of section */ int32_t symbol; /* symbol index */ int type; /* type of relocation */ }; struct Symbol { int32_t strpos; /* string table position of name */ int32_t section; /* section ID of the symbol */ int type; /* symbol type */ int other; /* symbol visibility */ int32_t value; /* address, or COMMON variable align */ int32_t size; /* size of symbol */ int32_t globnum; /* symbol table offset if global */ struct Symbol *next; /* list of globals in each section */ struct Symbol *nextfwd; /* list of unresolved-size symbols */ char *name; /* used temporarily if in above list */ }; #define SHT_PROGBITS 1 #define SHT_NOBITS 8 #define SHF_WRITE 1 #define SHF_ALLOC 2 #define SHF_EXECINSTR 4 struct Section { struct SAA *data; uint32_t len, size, nrelocs; int32_t index; int type; /* SHT_PROGBITS or SHT_NOBITS */ int align; /* alignment: power of two */ uint32_t flags; /* section flags */ char *name; struct SAA *rel; int32_t rellen; struct Reloc *head, **tail; struct Symbol *gsyms; /* global symbols in section */ }; #define SECT_DELTA 32 static struct Section **sects; static int nsects, sectlen; #define SHSTR_DELTA 256 static char *shstrtab; static int shstrtablen, shstrtabsize; static struct SAA *syms; static uint32_t nlocals, nglobs; static int32_t def_seg; static struct RAA *bsym; static struct SAA *strs; static uint32_t strslen; static FILE *elffp; static efunc error; static evalfunc evaluate; static struct Symbol *fwds; static char elf_module[FILENAME_MAX]; extern struct ofmt of_elf32; extern struct ofmt of_elf; #define SHN_ABS 0xFFF1 #define SHN_COMMON 0xFFF2 #define SHN_UNDEF 0 #define SYM_GLOBAL 0x10 #define STT_NOTYPE 0 /* Symbol type is unspecified */ #define STT_OBJECT 1 /* Symbol is a data object */ #define STT_FUNC 2 /* Symbol is a code object */ #define STT_SECTION 3 /* Symbol associated with a section */ #define STT_FILE 4 /* Symbol's name is file name */ #define STT_COMMON 5 /* Symbol is a common data object */ #define STT_TLS 6 /* Symbol is thread-local data object*/ #define STT_NUM 7 /* Number of defined types. */ #define STV_DEFAULT 0 #define STV_INTERNAL 1 #define STV_HIDDEN 2 #define STV_PROTECTED 3 #define GLOBAL_TEMP_BASE 16 /* bigger than any constant sym id */ #define SEG_ALIGN 16 /* alignment of sections in file */ #define SEG_ALIGN_1 (SEG_ALIGN-1) static const char align_str[SEG_ALIGN] = ""; /* ANSI will pad this with 0s */ #define ELF_MAX_SECTIONS 16 /* really 10, but let's play safe */ static struct ELF_SECTDATA { void *data; int32_t len; bool is_saa; } *elf_sects; static int elf_nsect; static int32_t elf_foffs; static void elf_write(void); static void elf_sect_write(struct Section *, const uint8_t *, uint32_t); static void elf_section_header(int, int, int, void *, bool, int32_t, int, int, int, int); static void elf_write_sections(void); static struct SAA *elf_build_symtab(int32_t *, int32_t *); static struct SAA *elf_build_reltab(int32_t *, struct Reloc *); static void add_sectname(char *, char *); /* this stuff is needed for the stabs debugging format */ #define N_SO 0x64 /* ID for main source file */ #define N_SOL 0x84 /* ID for sub-source file */ #define N_BINCL 0x82 #define N_EINCL 0xA2 #define N_SLINE 0x44 #define TY_STABSSYMLIN 0x40 /* ouch */ struct stabentry { uint32_t n_strx; uint8_t n_type; uint8_t n_other; uint16_t n_desc; uint32_t n_value; }; struct erel { int offset, info; }; struct symlininfo { int offset; int section; /* section index */ char *name; /* shallow-copied pointer of section name */ }; struct linelist { struct symlininfo info; int line; char *filename; struct linelist *next; struct linelist *last; }; static struct linelist *stabslines = 0; static int stabs_immcall = 0; static int currentline = 0; static int numlinestabs = 0; static char *stabs_filename = 0; static int symtabsection; static uint8_t *stabbuf = 0, *stabstrbuf = 0, *stabrelbuf = 0; static int stablen, stabstrlen, stabrellen; static struct dfmt df_stabs; static struct Symbol *lastsym; void stabs32_init(struct ofmt *, void *, FILE *, efunc); void stabs32_linenum(const char *filename, int32_t linenumber, int32_t); void stabs32_deflabel(char *, int32_t, int64_t, int, char *); void stabs32_directive(const char *, const char *); void stabs32_typevalue(int32_t); void stabs32_output(int, void *); void stabs32_generate(void); void stabs32_cleanup(void); /* end of stabs debugging stuff */ /* * Special section numbers which are used to define ELF special * symbols, which can be used with WRT to provide PIC relocation * types. */ static int32_t elf_gotpc_sect, elf_gotoff_sect; static int32_t elf_got_sect, elf_plt_sect; static int32_t elf_sym_sect; static void elf_init(FILE * fp, efunc errfunc, ldfunc ldef, evalfunc eval) { elffp = fp; error = errfunc; evaluate = eval; (void)ldef; /* placate optimisers */ sects = NULL; nsects = sectlen = 0; syms = saa_init((int32_t)sizeof(struct Symbol)); nlocals = nglobs = 0; bsym = raa_init(); strs = saa_init(1L); saa_wbytes(strs, "\0", 1L); saa_wbytes(strs, elf_module, (int32_t)(strlen(elf_module) + 1)); strslen = 2 + strlen(elf_module); shstrtab = NULL; shstrtablen = shstrtabsize = 0;; add_sectname("", ""); fwds = NULL; elf_gotpc_sect = seg_alloc(); ldef("..gotpc", elf_gotpc_sect + 1, 0L, NULL, false, false, &of_elf32, error); elf_gotoff_sect = seg_alloc(); ldef("..gotoff", elf_gotoff_sect + 1, 0L, NULL, false, false, &of_elf32, error); elf_got_sect = seg_alloc(); ldef("..got", elf_got_sect + 1, 0L, NULL, false, false, &of_elf32, error); elf_plt_sect = seg_alloc(); ldef("..plt", elf_plt_sect + 1, 0L, NULL, false, false, &of_elf32, error); elf_sym_sect = seg_alloc(); ldef("..sym", elf_sym_sect + 1, 0L, NULL, false, false, &of_elf32, error); def_seg = seg_alloc(); } static void elf_cleanup(int debuginfo) { struct Reloc *r; int i; (void)debuginfo; elf_write(); fclose(elffp); for (i = 0; i < nsects; i++) { if (sects[i]->type != SHT_NOBITS) saa_free(sects[i]->data); if (sects[i]->head) saa_free(sects[i]->rel); while (sects[i]->head) { r = sects[i]->head; sects[i]->head = sects[i]->head->next; nasm_free(r); } } nasm_free(sects); saa_free(syms); raa_free(bsym); saa_free(strs); if (of_elf32.current_dfmt) { of_elf32.current_dfmt->cleanup(); } } static void add_sectname(char *firsthalf, char *secondhalf) { int len = strlen(firsthalf) + strlen(secondhalf); while (shstrtablen + len + 1 > shstrtabsize) shstrtab = nasm_realloc(shstrtab, (shstrtabsize += SHSTR_DELTA)); strcpy(shstrtab + shstrtablen, firsthalf); strcat(shstrtab + shstrtablen, secondhalf); shstrtablen += len + 1; } static int elf_make_section(char *name, int type, int flags, int align) { struct Section *s; s = nasm_malloc(sizeof(*s)); if (type != SHT_NOBITS) s->data = saa_init(1L); s->head = NULL; s->tail = &s->head; s->len = s->size = 0; s->nrelocs = 0; if (!strcmp(name, ".text")) s->index = def_seg; else s->index = seg_alloc(); add_sectname("", name); s->name = nasm_malloc(1 + strlen(name)); strcpy(s->name, name); s->type = type; s->flags = flags; s->align = align; s->gsyms = NULL; if (nsects >= sectlen) sects = nasm_realloc(sects, (sectlen += SECT_DELTA) * sizeof(*sects)); sects[nsects++] = s; return nsects - 1; } static int32_t elf_section_names(char *name, int pass, int *bits) { char *p; unsigned flags_and, flags_or; int type, align, i; /* * Default is 32 bits. */ if (!name) { *bits = 32; return def_seg; } p = name; while (*p && !isspace(*p)) p++; if (*p) *p++ = '\0'; flags_and = flags_or = type = align = 0; while (*p && isspace(*p)) p++; while (*p) { char *q = p; while (*p && !isspace(*p)) p++; if (*p) *p++ = '\0'; while (*p && isspace(*p)) p++; if (!nasm_strnicmp(q, "align=", 6)) { align = atoi(q + 6); if (align == 0) align = 1; if ((align - 1) & align) { /* means it's not a power of two */ error(ERR_NONFATAL, "section alignment %d is not" " a power of two", align); align = 1; } } else if (!nasm_stricmp(q, "alloc")) { flags_and |= SHF_ALLOC; flags_or |= SHF_ALLOC; } else if (!nasm_stricmp(q, "noalloc")) { flags_and |= SHF_ALLOC; flags_or &= ~SHF_ALLOC; } else if (!nasm_stricmp(q, "exec")) { flags_and |= SHF_EXECINSTR; flags_or |= SHF_EXECINSTR; } else if (!nasm_stricmp(q, "noexec")) { flags_and |= SHF_EXECINSTR; flags_or &= ~SHF_EXECINSTR; } else if (!nasm_stricmp(q, "write")) { flags_and |= SHF_WRITE; flags_or |= SHF_WRITE; } else if (!nasm_stricmp(q, "nowrite")) { flags_and |= SHF_WRITE; flags_or &= ~SHF_WRITE; } else if (!nasm_stricmp(q, "progbits")) { type = SHT_PROGBITS; } else if (!nasm_stricmp(q, "nobits")) { type = SHT_NOBITS; } } if (!strcmp(name, ".comment") || !strcmp(name, ".shstrtab") || !strcmp(name, ".symtab") || !strcmp(name, ".strtab")) { error(ERR_NONFATAL, "attempt to redefine reserved section" "name `%s'", name); return NO_SEG; } for (i = 0; i < nsects; i++) if (!strcmp(name, sects[i]->name)) break; if (i == nsects) { if (!strcmp(name, ".text")) i = elf_make_section(name, SHT_PROGBITS, SHF_ALLOC | SHF_EXECINSTR, 16); else if (!strcmp(name, ".rodata")) i = elf_make_section(name, SHT_PROGBITS, SHF_ALLOC, 4); else if (!strcmp(name, ".data")) i = elf_make_section(name, SHT_PROGBITS, SHF_ALLOC | SHF_WRITE, 4); else if (!strcmp(name, ".bss")) i = elf_make_section(name, SHT_NOBITS, SHF_ALLOC | SHF_WRITE, 4); else i = elf_make_section(name, SHT_PROGBITS, SHF_ALLOC, 1); if (type) sects[i]->type = type; if (align) sects[i]->align = align; sects[i]->flags &= ~flags_and; sects[i]->flags |= flags_or; } else if (pass == 1) { if ((type && sects[i]->type != type) || (align && sects[i]->align != align) || (flags_and && ((sects[i]->flags & flags_and) != flags_or))) error(ERR_WARNING, "section attributes ignored on" " redeclaration of section `%s'", name); } return sects[i]->index; } static void elf_deflabel(char *name, int32_t segment, int64_t offset, int is_global, char *special) { int pos = strslen; struct Symbol *sym; bool special_used = false; #if defined(DEBUG) && DEBUG>2 fprintf(stderr, " elf_deflabel: %s, seg=%ld, off=%ld, is_global=%d, %s\n", name, segment, offset, is_global, special); #endif if (name[0] == '.' && name[1] == '.' && name[2] != '@') { /* * This is a NASM special symbol. We never allow it into * the ELF symbol table, even if it's a valid one. If it * _isn't_ a valid one, we should barf immediately. */ if (strcmp(name, "..gotpc") && strcmp(name, "..gotoff") && strcmp(name, "..got") && strcmp(name, "..plt") && strcmp(name, "..sym")) error(ERR_NONFATAL, "unrecognised special symbol `%s'", name); return; } if (is_global == 3) { struct Symbol **s; /* * Fix up a forward-reference symbol size from the first * pass. */ for (s = &fwds; *s; s = &(*s)->nextfwd) if (!strcmp((*s)->name, name)) { struct tokenval tokval; expr *e; char *p = special; while (*p && !isspace(*p)) p++; while (*p && isspace(*p)) p++; stdscan_reset(); stdscan_bufptr = p; tokval.t_type = TOKEN_INVALID; e = evaluate(stdscan, NULL, &tokval, NULL, 1, error, NULL); if (e) { if (!is_simple(e)) error(ERR_NONFATAL, "cannot use relocatable" " expression as symbol size"); else (*s)->size = reloc_value(e); } /* * Remove it from the list of unresolved sizes. */ nasm_free((*s)->name); *s = (*s)->nextfwd; return; } return; /* it wasn't an important one */ } saa_wbytes(strs, name, (int32_t)(1 + strlen(name))); strslen += 1 + strlen(name); lastsym = sym = saa_wstruct(syms); sym->strpos = pos; sym->type = is_global ? SYM_GLOBAL : 0; sym->other = STV_DEFAULT; sym->size = 0; if (segment == NO_SEG) sym->section = SHN_ABS; else { int i; sym->section = SHN_UNDEF; if (nsects == 0 && segment == def_seg) { int tempint; if (segment != elf_section_names(".text", 2, &tempint)) error(ERR_PANIC, "strange segment conditions in ELF driver"); sym->section = nsects; } else { for (i = 0; i < nsects; i++) if (segment == sects[i]->index) { sym->section = i + 1; break; } } } if (is_global == 2) { sym->size = offset; sym->value = 0; sym->section = SHN_COMMON; /* * We have a common variable. Check the special text to see * if it's a valid number and power of two; if so, store it * as the alignment for the common variable. */ if (special) { bool err; sym->value = readnum(special, &err); if (err) error(ERR_NONFATAL, "alignment constraint `%s' is not a" " valid number", special); else if ((sym->value | (sym->value - 1)) != 2 * sym->value - 1) error(ERR_NONFATAL, "alignment constraint `%s' is not a" " power of two", special); } special_used = true; } else sym->value = (sym->section == SHN_UNDEF ? 0 : offset); if (sym->type == SYM_GLOBAL) { /* * If sym->section == SHN_ABS, then the first line of the * else section would cause a core dump, because its a reference * beyond the end of the section array. * This behaviour is exhibited by this code: * GLOBAL crash_nasm * crash_nasm equ 0 * To avoid such a crash, such requests are silently discarded. * This may not be the best solution. */ if (sym->section == SHN_UNDEF || sym->section == SHN_COMMON) { bsym = raa_write(bsym, segment, nglobs); } else if (sym->section != SHN_ABS) { /* * This is a global symbol; so we must add it to the linked * list of global symbols in its section. We'll push it on * the beginning of the list, because it doesn't matter * much which end we put it on and it's easier like this. * * In addition, we check the special text for symbol * type and size information. */ sym->next = sects[sym->section - 1]->gsyms; sects[sym->section - 1]->gsyms = sym; if (special) { int n = strcspn(special, " \t"); if (!nasm_strnicmp(special, "function", n)) sym->type |= STT_FUNC; else if (!nasm_strnicmp(special, "data", n) || !nasm_strnicmp(special, "object", n)) sym->type |= STT_OBJECT; else if (!nasm_strnicmp(special, "notype", n)) sym->type |= STT_NOTYPE; else error(ERR_NONFATAL, "unrecognised symbol type `%.*s'", n, special); special += n; while (isspace(*special)) ++special; if (*special) { n = strcspn(special, " \t"); if (!nasm_strnicmp(special, "default", n)) sym->other = STV_DEFAULT; else if (!nasm_strnicmp(special, "internal", n)) sym->other = STV_INTERNAL; else if (!nasm_strnicmp(special, "hidden", n)) sym->other = STV_HIDDEN; else if (!nasm_strnicmp(special, "protected", n)) sym->other = STV_PROTECTED; else n = 0; special += n; } if (*special) { struct tokenval tokval; expr *e; int fwd = 0; char *saveme = stdscan_bufptr; /* bugfix? fbk 8/10/00 */ while (special[n] && isspace(special[n])) n++; /* * We have a size expression; attempt to * evaluate it. */ stdscan_reset(); stdscan_bufptr = special + n; tokval.t_type = TOKEN_INVALID; e = evaluate(stdscan, NULL, &tokval, &fwd, 0, error, NULL); if (fwd) { sym->nextfwd = fwds; fwds = sym; sym->name = nasm_strdup(name); } else if (e) { if (!is_simple(e)) error(ERR_NONFATAL, "cannot use relocatable" " expression as symbol size"); else sym->size = reloc_value(e); } stdscan_bufptr = saveme; /* bugfix? fbk 8/10/00 */ } special_used = true; } } sym->globnum = nglobs; nglobs++; } else nlocals++; if (special && !special_used) error(ERR_NONFATAL, "no special symbol features supported here"); } static void elf_add_reloc(struct Section *sect, int32_t segment, int type) { struct Reloc *r; r = *sect->tail = nasm_malloc(sizeof(struct Reloc)); sect->tail = &r->next; r->next = NULL; r->address = sect->len; if (segment == NO_SEG) r->symbol = 0; else { int i; r->symbol = 0; for (i = 0; i < nsects; i++) if (segment == sects[i]->index) r->symbol = i + 2; if (!r->symbol) r->symbol = GLOBAL_TEMP_BASE + raa_read(bsym, segment); } r->type = type; sect->nrelocs++; } /* * This routine deals with ..got and ..sym relocations: the more * complicated kinds. In shared-library writing, some relocations * with respect to global symbols must refer to the precise symbol * rather than referring to an offset from the base of the section * _containing_ the symbol. Such relocations call to this routine, * which searches the symbol list for the symbol in question. * * R_386_GOT32 references require the _exact_ symbol address to be * used; R_386_32 references can be at an offset from the symbol. * The boolean argument `exact' tells us this. * * Return value is the adjusted value of `addr', having become an * offset from the symbol rather than the section. Should always be * zero when returning from an exact call. * * Limitation: if you define two symbols at the same place, * confusion will occur. * * Inefficiency: we search, currently, using a linked list which * isn't even necessarily sorted. */ static int32_t elf_add_gsym_reloc(struct Section *sect, int32_t segment, int32_t offset, int type, bool exact) { struct Reloc *r; struct Section *s; struct Symbol *sym, *sm; int i; /* * First look up the segment/offset pair and find a global * symbol corresponding to it. If it's not one of our segments, * then it must be an external symbol, in which case we're fine * doing a normal elf_add_reloc after first sanity-checking * that the offset from the symbol is zero. */ s = NULL; for (i = 0; i < nsects; i++) if (segment == sects[i]->index) { s = sects[i]; break; } if (!s) { if (exact && offset != 0) error(ERR_NONFATAL, "unable to find a suitable global symbol" " for this reference"); else elf_add_reloc(sect, segment, type); return offset; } if (exact) { /* * Find a symbol pointing _exactly_ at this one. */ for (sym = s->gsyms; sym; sym = sym->next) if (sym->value == offset) break; } else { /* * Find the nearest symbol below this one. */ sym = NULL; for (sm = s->gsyms; sm; sm = sm->next) if (sm->value <= offset && (!sym || sm->value > sym->value)) sym = sm; } if (!sym && exact) { error(ERR_NONFATAL, "unable to find a suitable global symbol" " for this reference"); return 0; } r = *sect->tail = nasm_malloc(sizeof(struct Reloc)); sect->tail = &r->next; r->next = NULL; r->address = sect->len; r->symbol = GLOBAL_TEMP_BASE + sym->globnum; r->type = type; sect->nrelocs++; return offset - sym->value; } static void elf_out(int32_t segto, const void *data, enum out_type type, uint64_t size, int32_t segment, int32_t wrt) { struct Section *s; int32_t addr; uint8_t mydata[4], *p; int i; static struct symlininfo sinfo; /* * handle absolute-assembly (structure definitions) */ if (segto == NO_SEG) { if (type != OUT_RESERVE) error(ERR_NONFATAL, "attempt to assemble code in [ABSOLUTE]" " space"); return; } s = NULL; for (i = 0; i < nsects; i++) if (segto == sects[i]->index) { s = sects[i]; break; } if (!s) { int tempint; /* ignored */ if (segto != elf_section_names(".text", 2, &tempint)) error(ERR_PANIC, "strange segment conditions in ELF driver"); else { s = sects[nsects - 1]; i = nsects - 1; } } /* again some stabs debugging stuff */ if (of_elf32.current_dfmt) { sinfo.offset = s->len; sinfo.section = i; sinfo.name = s->name; of_elf32.current_dfmt->debug_output(TY_STABSSYMLIN, &sinfo); } /* end of debugging stuff */ if (s->type == SHT_NOBITS && type != OUT_RESERVE) { error(ERR_WARNING, "attempt to initialize memory in" " BSS section `%s': ignored", s->name); if (type == OUT_REL2ADR) size = 2; else if (type == OUT_REL4ADR) size = 4; s->len += size; return; } if (type == OUT_RESERVE) { if (s->type == SHT_PROGBITS) { error(ERR_WARNING, "uninitialized space declared in" " non-BSS section `%s': zeroing", s->name); elf_sect_write(s, NULL, size); } else s->len += size; } else if (type == OUT_RAWDATA) { if (segment != NO_SEG) error(ERR_PANIC, "OUT_RAWDATA with other than NO_SEG"); elf_sect_write(s, data, size); } else if (type == OUT_ADDRESS) { bool gnu16 = false; addr = *(int32_t *)data; if (segment != NO_SEG) { if (segment % 2) { error(ERR_NONFATAL, "ELF format does not support" " segment base references"); } else { if (wrt == NO_SEG) { if (size == 2) { gnu16 = true; elf_add_reloc(s, segment, R_386_16); } else { elf_add_reloc(s, segment, R_386_32); } } else if (wrt == elf_gotpc_sect + 1) { /* * The user will supply GOT relative to $$. ELF * will let us have GOT relative to $. So we * need to fix up the data item by $-$$. */ addr += s->len; elf_add_reloc(s, segment, R_386_GOTPC); } else if (wrt == elf_gotoff_sect + 1) { elf_add_reloc(s, segment, R_386_GOTOFF); } else if (wrt == elf_got_sect + 1) { addr = elf_add_gsym_reloc(s, segment, addr, R_386_GOT32, true); } else if (wrt == elf_sym_sect + 1) { if (size == 2) { gnu16 = true; addr = elf_add_gsym_reloc(s, segment, addr, R_386_16, false); } else { addr = elf_add_gsym_reloc(s, segment, addr, R_386_32, false); } } else if (wrt == elf_plt_sect + 1) { error(ERR_NONFATAL, "ELF format cannot produce non-PC-" "relative PLT references"); } else { error(ERR_NONFATAL, "ELF format does not support this" " use of WRT"); wrt = NO_SEG; /* we can at least _try_ to continue */ } } } p = mydata; if (gnu16) { error(ERR_WARNING | ERR_WARN_GNUELF, "16-bit relocations in ELF is a GNU extension"); WRITESHORT(p, addr); } else { if (size != 4 && segment != NO_SEG) { error(ERR_NONFATAL, "Unsupported non-32-bit ELF relocation"); } WRITELONG(p, addr); } elf_sect_write(s, mydata, size); } else if (type == OUT_REL2ADR) { if (segment == segto) error(ERR_PANIC, "intra-segment OUT_REL2ADR"); if (segment != NO_SEG && segment % 2) { error(ERR_NONFATAL, "ELF format does not support" " segment base references"); } else { if (wrt == NO_SEG) { error(ERR_WARNING | ERR_WARN_GNUELF, "16-bit relocations in ELF is a GNU extension"); elf_add_reloc(s, segment, R_386_PC16); } else { error(ERR_NONFATAL, "Unsupported non-32-bit ELF relocation"); } } p = mydata; WRITESHORT(p, *(int32_t *)data - size); elf_sect_write(s, mydata, 2L); } else if (type == OUT_REL4ADR) { if (segment == segto) error(ERR_PANIC, "intra-segment OUT_REL4ADR"); if (segment != NO_SEG && segment % 2) { error(ERR_NONFATAL, "ELF format does not support" " segment base references"); } else { if (wrt == NO_SEG) { elf_add_reloc(s, segment, R_386_PC32); } else if (wrt == elf_plt_sect + 1) { elf_add_reloc(s, segment, R_386_PLT32); } else if (wrt == elf_gotpc_sect + 1 || wrt == elf_gotoff_sect + 1 || wrt == elf_got_sect + 1) { error(ERR_NONFATAL, "ELF format cannot produce PC-" "relative GOT references"); } else { error(ERR_NONFATAL, "ELF format does not support this" " use of WRT"); wrt = NO_SEG; /* we can at least _try_ to continue */ } } p = mydata; WRITELONG(p, *(int32_t *)data - size); elf_sect_write(s, mydata, 4L); } } static void elf_write(void) { int nsections, align; int scount; char *p; int commlen; char comment[64]; int i; struct SAA *symtab; int32_t symtablen, symtablocal; /* * Work out how many sections we will have. We have SHN_UNDEF, * then the flexible user sections, then the four fixed * sections `.comment', `.shstrtab', `.symtab' and `.strtab', * then optionally relocation sections for the user sections. */ if (of_elf32.current_dfmt == &df_stabs) nsections = 8; else nsections = 5; /* SHN_UNDEF and the fixed ones */ add_sectname("", ".comment"); add_sectname("", ".shstrtab"); add_sectname("", ".symtab"); add_sectname("", ".strtab"); for (i = 0; i < nsects; i++) { nsections++; /* for the section itself */ if (sects[i]->head) { nsections++; /* for its relocations */ add_sectname(".rel", sects[i]->name); } } if (of_elf32.current_dfmt == &df_stabs) { /* in case the debug information is wanted, just add these three sections... */ add_sectname("", ".stab"); add_sectname("", ".stabstr"); add_sectname(".rel", ".stab"); } /* * Do the comment. */ *comment = '\0'; commlen = 2 + sprintf(comment + 1, "The Netwide Assembler %s", NASM_VER); /* * Output the ELF header. */ fwrite("\177ELF\1\1\1\0\0\0\0\0\0\0\0\0", 16, 1, elffp); fwriteint16_t(1, elffp); /* ET_REL relocatable file */ fwriteint16_t(3, elffp); /* EM_386 processor ID */ fwriteint32_t(1L, elffp); /* EV_CURRENT file format version */ fwriteint32_t(0L, elffp); /* no entry point */ fwriteint32_t(0L, elffp); /* no program header table */ fwriteint32_t(0x40L, elffp); /* section headers straight after * ELF header plus alignment */ fwriteint32_t(0L, elffp); /* 386 defines no special flags */ fwriteint16_t(0x34, elffp); /* size of ELF header */ fwriteint16_t(0, elffp); /* no program header table, again */ fwriteint16_t(0, elffp); /* still no program header table */ fwriteint16_t(0x28, elffp); /* size of section header */ fwriteint16_t(nsections, elffp); /* number of sections */ fwriteint16_t(nsects + 2, elffp); /* string table section index for * section header table */ fwriteint32_t(0L, elffp); /* align to 0x40 bytes */ fwriteint32_t(0L, elffp); fwriteint32_t(0L, elffp); /* * Build the symbol table and relocation tables. */ symtab = elf_build_symtab(&symtablen, &symtablocal); for (i = 0; i < nsects; i++) if (sects[i]->head) sects[i]->rel = elf_build_reltab(§s[i]->rellen, sects[i]->head); /* * Now output the section header table. */ elf_foffs = 0x40 + 0x28 * nsections; align = ((elf_foffs + SEG_ALIGN_1) & ~SEG_ALIGN_1) - elf_foffs; elf_foffs += align; elf_nsect = 0; elf_sects = nasm_malloc(sizeof(*elf_sects) * (2 * nsects + 10)); elf_section_header(0, 0, 0, NULL, false, 0L, 0, 0, 0, 0); /* SHN_UNDEF */ scount = 1; /* needed for the stabs debugging to track the symtable section */ p = shstrtab + 1; for (i = 0; i < nsects; i++) { elf_section_header(p - shstrtab, sects[i]->type, sects[i]->flags, (sects[i]->type == SHT_PROGBITS ? sects[i]->data : NULL), true, sects[i]->len, 0, 0, sects[i]->align, 0); p += strlen(p) + 1; scount++; /* dito */ } elf_section_header(p - shstrtab, 1, 0, comment, false, (int32_t)commlen, 0, 0, 1, 0); /* .comment */ scount++; /* dito */ p += strlen(p) + 1; elf_section_header(p - shstrtab, 3, 0, shstrtab, false, (int32_t)shstrtablen, 0, 0, 1, 0); /* .shstrtab */ scount++; /* dito */ p += strlen(p) + 1; elf_section_header(p - shstrtab, 2, 0, symtab, true, symtablen, nsects + 4, symtablocal, 4, 16); /* .symtab */ symtabsection = scount; /* now we got the symtab section index in the ELF file */ p += strlen(p) + 1; elf_section_header(p - shstrtab, 3, 0, strs, true, strslen, 0, 0, 1, 0); /* .strtab */ for (i = 0; i < nsects; i++) if (sects[i]->head) { p += strlen(p) + 1; elf_section_header(p - shstrtab, 9, 0, sects[i]->rel, true, sects[i]->rellen, nsects + 3, i + 1, 4, 8); } if (of_elf32.current_dfmt == &df_stabs) { /* for debugging information, create the last three sections which are the .stab , .stabstr and .rel.stab sections respectively */ /* this function call creates the stab sections in memory */ stabs32_generate(); if ((stabbuf) && (stabstrbuf) && (stabrelbuf)) { p += strlen(p) + 1; elf_section_header(p - shstrtab, 1, 0, stabbuf, false, stablen, nsections - 2, 0, 4, 12); p += strlen(p) + 1; elf_section_header(p - shstrtab, 3, 0, stabstrbuf, false, stabstrlen, 0, 0, 4, 0); p += strlen(p) + 1; /* link -> symtable info -> section to refer to */ elf_section_header(p - shstrtab, 9, 0, stabrelbuf, false, stabrellen, symtabsection, nsections - 3, 4, 8); } } fwrite(align_str, align, 1, elffp); /* * Now output the sections. */ elf_write_sections(); nasm_free(elf_sects); saa_free(symtab); } static struct SAA *elf_build_symtab(int32_t *len, int32_t *local) { struct SAA *s = saa_init(1L); struct Symbol *sym; uint8_t entry[16], *p; int i; *len = *local = 0; /* * First, an all-zeros entry, required by the ELF spec. */ saa_wbytes(s, NULL, 16L); /* null symbol table entry */ *len += 16; (*local)++; /* * Next, an entry for the file name. */ p = entry; WRITELONG(p, 1); /* we know it's 1st entry in strtab */ WRITELONG(p, 0); /* no value */ WRITELONG(p, 0); /* no size either */ WRITESHORT(p, STT_FILE); /* type FILE */ WRITESHORT(p, SHN_ABS); saa_wbytes(s, entry, 16L); *len += 16; (*local)++; /* * Now some standard symbols defining the segments, for relocation * purposes. */ for (i = 1; i <= nsects; i++) { p = entry; WRITELONG(p, 0); /* no symbol name */ WRITELONG(p, 0); /* offset zero */ WRITELONG(p, 0); /* size zero */ WRITESHORT(p, STT_SECTION); /* type, binding, and visibility */ WRITESHORT(p, i); /* section id */ saa_wbytes(s, entry, 16L); *len += 16; (*local)++; } /* * Now the other local symbols. */ saa_rewind(syms); while ((sym = saa_rstruct(syms))) { if (sym->type & SYM_GLOBAL) continue; p = entry; WRITELONG(p, sym->strpos); WRITELONG(p, sym->value); WRITELONG(p, sym->size); WRITECHAR(p, sym->type); /* type and binding */ WRITECHAR(p, sym->other); /* visibility */ WRITESHORT(p, sym->section); saa_wbytes(s, entry, 16L); *len += 16; (*local)++; } /* * Now the global symbols. */ saa_rewind(syms); while ((sym = saa_rstruct(syms))) { if (!(sym->type & SYM_GLOBAL)) continue; p = entry; WRITELONG(p, sym->strpos); WRITELONG(p, sym->value); WRITELONG(p, sym->size); WRITECHAR(p, sym->type); /* type and binding */ WRITECHAR(p, sym->other); /* visibility */ WRITESHORT(p, sym->section); saa_wbytes(s, entry, 16L); *len += 16; } return s; } static struct SAA *elf_build_reltab(int32_t *len, struct Reloc *r) { struct SAA *s; uint8_t *p, entry[8]; if (!r) return NULL; s = saa_init(1L); *len = 0; while (r) { int32_t sym = r->symbol; if (sym >= GLOBAL_TEMP_BASE) sym += -GLOBAL_TEMP_BASE + (nsects + 2) + nlocals; p = entry; WRITELONG(p, r->address); WRITELONG(p, (sym << 8) + r->type); saa_wbytes(s, entry, 8L); *len += 8; r = r->next; } return s; } static void elf_section_header(int name, int type, int flags, void *data, bool is_saa, int32_t datalen, int link, int info, int align, int eltsize) { elf_sects[elf_nsect].data = data; elf_sects[elf_nsect].len = datalen; elf_sects[elf_nsect].is_saa = is_saa; elf_nsect++; fwriteint32_t((int32_t)name, elffp); fwriteint32_t((int32_t)type, elffp); fwriteint32_t((int32_t)flags, elffp); fwriteint32_t(0L, elffp); /* no address, ever, in object files */ fwriteint32_t(type == 0 ? 0L : elf_foffs, elffp); fwriteint32_t(datalen, elffp); if (data) elf_foffs += (datalen + SEG_ALIGN_1) & ~SEG_ALIGN_1; fwriteint32_t((int32_t)link, elffp); fwriteint32_t((int32_t)info, elffp); fwriteint32_t((int32_t)align, elffp); fwriteint32_t((int32_t)eltsize, elffp); } static void elf_write_sections(void) { int i; for (i = 0; i < elf_nsect; i++) if (elf_sects[i].data) { int32_t len = elf_sects[i].len; int32_t reallen = (len + SEG_ALIGN_1) & ~SEG_ALIGN_1; int32_t align = reallen - len; if (elf_sects[i].is_saa) saa_fpwrite(elf_sects[i].data, elffp); else fwrite(elf_sects[i].data, len, 1, elffp); fwrite(align_str, align, 1, elffp); } } static void elf_sect_write(struct Section *sect, const uint8_t *data, uint32_t len) { saa_wbytes(sect->data, data, len); sect->len += len; } static int32_t elf_segbase(int32_t segment) { return segment; } static int elf_directive(char *directive, char *value, int pass) { (void)directive; (void)value; (void)pass; return 0; } static void elf_filename(char *inname, char *outname, efunc error) { strcpy(elf_module, inname); standard_extension(inname, outname, ".o", error); } static const char *elf_stdmac[] = { "%define __SECT__ [section .text]", "%macro __NASM_CDecl__ 1", "%define $_%1 $%1", "%endmacro", NULL }; static int elf_set_info(enum geninfo type, char **val) { (void)type; (void)val; return 0; } static struct dfmt df_stabs = { "ELF32 (i386) stabs debug format for Linux", "stabs", stabs32_init, stabs32_linenum, stabs32_deflabel, stabs32_directive, stabs32_typevalue, stabs32_output, stabs32_cleanup }; struct dfmt *elf32_debugs_arr[2] = { &df_stabs, NULL }; struct ofmt of_elf32 = { "ELF32 (i386) object files (e.g. Linux)", "elf32", NULL, elf32_debugs_arr, &null_debug_form, elf_stdmac, elf_init, elf_set_info, elf_out, elf_deflabel, elf_section_names, elf_segbase, elf_directive, elf_filename, elf_cleanup }; struct ofmt of_elf = { "ELF (short name for ELF32) ", "elf", NULL, elf32_debugs_arr, &null_debug_form, elf_stdmac, elf_init, elf_set_info, elf_out, elf_deflabel, elf_section_names, elf_segbase, elf_directive, elf_filename, elf_cleanup }; /* again, the stabs debugging stuff (code) */ void stabs32_init(struct ofmt *of, void *id, FILE * fp, efunc error) { (void)of; (void)id; (void)fp; (void)error; } void stabs32_linenum(const char *filename, int32_t linenumber, int32_t segto) { (void)segto; if (!stabs_filename) { stabs_filename = (char *)nasm_malloc(strlen(filename) + 1); strcpy(stabs_filename, filename); } else { if (strcmp(stabs_filename, filename)) { /* yep, a memory leak...this program is one-shot anyway, so who cares... in fact, this leak comes in quite handy to maintain a list of files encountered so far in the symbol lines... */ /* why not nasm_free(stabs_filename); we're done with the old one */ stabs_filename = (char *)nasm_malloc(strlen(filename) + 1); strcpy(stabs_filename, filename); } } stabs_immcall = 1; currentline = linenumber; } void stabs32_deflabel(char *name, int32_t segment, int64_t offset, int is_global, char *special) { (void)name; (void)segment; (void)offset; (void)is_global; (void)special; } void stabs32_directive(const char *directive, const char *params) { (void)directive; (void)params; } void stabs32_typevalue(int32_t type) { int32_t stype, ssize; switch (TYM_TYPE(type)) { case TY_LABEL: ssize = 0; stype = STT_NOTYPE; break; case TY_BYTE: ssize = 1; stype = STT_OBJECT; break; case TY_WORD: ssize = 2; stype = STT_OBJECT; break; case TY_DWORD: ssize = 4; stype = STT_OBJECT; break; case TY_FLOAT: ssize = 4; stype = STT_OBJECT; break; case TY_QWORD: ssize = 8; stype = STT_OBJECT; break; case TY_TBYTE: ssize = 10; stype = STT_OBJECT; break; case TY_OWORD: ssize = 8; stype = STT_OBJECT; break; case TY_COMMON: ssize = 0; stype = STT_COMMON; break; case TY_SEG: ssize = 0; stype = STT_SECTION; break; case TY_EXTERN: ssize = 0; stype = STT_NOTYPE; break; case TY_EQU: ssize = 0; stype = STT_NOTYPE; break; default: ssize = 0; stype = STT_NOTYPE; break; } if (stype == STT_OBJECT && !lastsym->type) { lastsym->size = ssize; lastsym->type = stype; } } void stabs32_output(int type, void *param) { struct symlininfo *s; struct linelist *el; if (type == TY_STABSSYMLIN) { if (stabs_immcall) { s = (struct symlininfo *)param; if (!(sects[s->section]->flags & SHF_EXECINSTR)) return; /* we are only interested in the text stuff */ numlinestabs++; el = (struct linelist *)nasm_malloc(sizeof(struct linelist)); el->info.offset = s->offset; el->info.section = s->section; el->info.name = s->name; el->line = currentline; el->filename = stabs_filename; el->next = 0; if (stabslines) { stabslines->last->next = el; stabslines->last = el; } else { stabslines = el; stabslines->last = el; } } } stabs_immcall = 0; } #define WRITE_STAB(p,n_strx,n_type,n_other,n_desc,n_value) \ do {\ WRITELONG(p,n_strx); \ WRITECHAR(p,n_type); \ WRITECHAR(p,n_other); \ WRITESHORT(p,n_desc); \ WRITELONG(p,n_value); \ } while (0) /* for creating the .stab , .stabstr and .rel.stab sections in memory */ void stabs32_generate(void) { int i, numfiles, strsize, numstabs = 0, currfile, mainfileindex; uint8_t *sbuf, *ssbuf, *rbuf, *sptr, *rptr; char **allfiles; int *fileidx; struct linelist *ptr; ptr = stabslines; allfiles = (char **)nasm_malloc(numlinestabs * sizeof(char *)); for (i = 0; i < numlinestabs; i++) allfiles[i] = 0; numfiles = 0; while (ptr) { if (numfiles == 0) { allfiles[0] = ptr->filename; numfiles++; } else { for (i = 0; i < numfiles; i++) { if (!strcmp(allfiles[i], ptr->filename)) break; } if (i >= numfiles) { allfiles[i] = ptr->filename; numfiles++; } } ptr = ptr->next; } strsize = 1; fileidx = (int *)nasm_malloc(numfiles * sizeof(int)); for (i = 0; i < numfiles; i++) { fileidx[i] = strsize; strsize += strlen(allfiles[i]) + 1; } mainfileindex = 0; for (i = 0; i < numfiles; i++) { if (!strcmp(allfiles[i], elf_module)) { mainfileindex = i; break; } } /* worst case size of the stab buffer would be: the sourcefiles changes each line, which would mean 1 SOL, 1 SYMLIN per line */ sbuf = (uint8_t *)nasm_malloc((numlinestabs * 2 + 3) * sizeof(struct stabentry)); ssbuf = (uint8_t *)nasm_malloc(strsize); rbuf = (uint8_t *)nasm_malloc(numlinestabs * 8 * (2 + 3)); rptr = rbuf; for (i = 0; i < numfiles; i++) { strcpy((char *)ssbuf + fileidx[i], allfiles[i]); } ssbuf[0] = 0; stabstrlen = strsize; /* set global variable for length of stab strings */ sptr = sbuf; ptr = stabslines; numstabs = 0; if (ptr) { /* this is the first stab, its strx points to the filename of the the source-file, the n_desc field should be set to the number of remaining stabs */ WRITE_STAB(sptr, fileidx[0], 0, 0, 0, strlen(allfiles[0] + 12)); /* this is the stab for the main source file */ WRITE_STAB(sptr, fileidx[mainfileindex], N_SO, 0, 0, 0); /* relocation table entry */ /* Since the symbol table has two entries before */ /* the section symbols, the index in the info.section */ /* member must be adjusted by adding 2 */ WRITELONG(rptr, (sptr - sbuf) - 4); WRITELONG(rptr, ((ptr->info.section + 2) << 8) | R_386_32); numstabs++; currfile = mainfileindex; } while (ptr) { if (strcmp(allfiles[currfile], ptr->filename)) { /* oops file has changed... */ for (i = 0; i < numfiles; i++) if (!strcmp(allfiles[i], ptr->filename)) break; currfile = i; WRITE_STAB(sptr, fileidx[currfile], N_SOL, 0, 0, ptr->info.offset); numstabs++; /* relocation table entry */ WRITELONG(rptr, (sptr - sbuf) - 4); WRITELONG(rptr, ((ptr->info.section + 2) << 8) | R_386_32); } WRITE_STAB(sptr, 0, N_SLINE, 0, ptr->line, ptr->info.offset); numstabs++; /* relocation table entry */ WRITELONG(rptr, (sptr - sbuf) - 4); WRITELONG(rptr, ((ptr->info.section + 2) << 8) | R_386_32); ptr = ptr->next; } ((struct stabentry *)sbuf)->n_desc = numstabs; nasm_free(allfiles); nasm_free(fileidx); stablen = (sptr - sbuf); stabrellen = (rptr - rbuf); stabrelbuf = rbuf; stabbuf = sbuf; stabstrbuf = ssbuf; } void stabs32_cleanup(void) { struct linelist *ptr, *del; if (!stabslines) return; ptr = stabslines; while (ptr) { del = ptr; ptr = ptr->next; nasm_free(del); } if (stabbuf) nasm_free(stabbuf); if (stabrelbuf) nasm_free(stabrelbuf); if (stabstrbuf) nasm_free(stabstrbuf); } #endif /* OF_ELF */