/* 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <inttypes.h>
#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];
static uint8_t elf_osabi = 0; /* Default OSABI = 0 (System V or Linux) */
static uint8_t elf_abiver = 0; /* Current ABI version */
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 = *(int64_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, *(int64_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, *(int64_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", 7, 1, elffp);
fputc(elf_osabi, elffp);
fputc(elf_abiver, elffp);
fwrite("\0\0\0\0\0\0\0", 7, 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)
{
bool err;
int64_t n;
char *p;
if (!strcmp(directive, "osabi")) {
if (pass == 2)
return 1; /* ignore in pass 2 */
n = readnum(value, &err);
if (err) {
error(ERR_NONFATAL, "`osabi' directive requires a parameter");
return 1;
}
if (n < 0 || n > 255) {
error(ERR_NONFATAL, "valid osabi numbers are 0 to 255");
return 1;
}
elf_osabi = n;
elf_abiver = 0;
if ((p = strchr(value,',')) == NULL)
return 1;
n = readnum(p+1, &err);
if (err || n < 0 || n > 255) {
error(ERR_NONFATAL, "invalid ABI version number (valid: 0 to 255)");
return 1;
}
elf_abiver = n;
return 1;
}
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",
"%macro osabi 1+.nolist",
"[osabi %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 */