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t_elf64.c
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t_elf64.c
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/* $VER: vlink t_elf64.c V0.17a (30.03.22)
*
* This file is part of vlink, a portable linker for multiple
* object formats.
* Copyright (c) 1997-2022 Frank Wille
*/
#include "config.h"
#ifdef ELF64
#define T_ELF64_C
#include "vlink.h"
#include "elf64.h"
/*#include "stabdefs.h" @@@ stabs are uncommon for 64-bit? */
/* static data required for output file generation */
static struct RelocList *reloclist;
static struct Section *dynamic;
/* stabs */
static struct ShdrNode *stabshdr;
/*static struct list stabcompunits;*/
static uint32_t stabdebugidx;
/*****************************************************************/
/* Read ELF */
/*****************************************************************/
static struct Elf64_Shdr *elf64_shdr(struct LinkFile *lf,
struct Elf64_Ehdr *ehdr,uint16_t idx)
/* return pointer to section header #idx */
{
bool be = (ehdr->e_ident[EI_DATA] == ELFDATA2MSB);
struct Elf64_Shdr *shdr;
if (idx < read16(be,ehdr->e_shnum)) {
shdr = (struct Elf64_Shdr *)(((char *)ehdr) + ((read32(be,ehdr->e_shoff) +
(uint32_t)read16(be,ehdr->e_shentsize) * (uint32_t)idx)));
if (((uint8_t *)shdr < lf->data) ||
(((uint8_t *)shdr)+read16(be,ehdr->e_shentsize) > lf->data+lf->length))
/* section header #x has illegal offset */
error(44,lf->pathname,(int)idx,lf->objname);
return shdr;
}
else /* Invalid ELF section header index */
error(43,lf->pathname,(int)idx,lf->objname);
return NULL; /* not reached, for compiler's sake */
}
static char *elf64_shstrtab(struct LinkFile *lf,struct Elf64_Ehdr *ehdr)
/* returns a pointer to the section header string table, if present, */
/* or NULL, otherwise */
{
bool be = (ehdr->e_ident[EI_DATA] == ELFDATA2MSB);
uint16_t i;
struct Elf64_Shdr *shdr;
char *stab;
if (i = read16(be,ehdr->e_shstrndx)) {
shdr = elf64_shdr(lf,ehdr,i);
if (read32(be,shdr->sh_type) != SHT_STRTAB)
error(45,lf->pathname,lf->objname); /* illegal type */
stab = ((char *)ehdr) + read64(be,shdr->sh_offset);
if (((uint8_t *)stab < lf->data) ||
((uint8_t *)stab + read64(be,shdr->sh_size) > lf->data + lf->length))
error(46,lf->pathname,lf->objname); /* illegal offset */
else
return stab;
}
return NULL;
}
static char *elf64_strtab(struct LinkFile *lf,struct Elf64_Ehdr *ehdr,int idx)
/* returns a pointer to the string table */
{
static char *tabname = "string";
bool be = (ehdr->e_ident[EI_DATA] == ELFDATA2MSB);
struct Elf64_Shdr *shdr;
char *stab;
shdr = elf64_shdr(lf,ehdr,idx);
if (read32(be,shdr->sh_type) != SHT_STRTAB)
error(50,lf->pathname,tabname,lf->objname); /* illegal type */
stab = ((char *)ehdr) + read64(be,shdr->sh_offset);
elf_check_offset(lf,tabname,stab,read64(be,shdr->sh_size));
return stab;
}
static struct Elf64_Sym *elf64_symtab(struct LinkFile *lf,
struct Elf64_Ehdr *ehdr,int idx)
/* returns a pointer to the symbol table */
{
static char *tabname = "symbol";
bool be = (ehdr->e_ident[EI_DATA] == ELFDATA2MSB);
struct Elf64_Shdr *shdr;
struct Elf64_Sym *symtab;
uint32_t shtype;
shdr = elf64_shdr(lf,ehdr,idx);
shtype = read32(be,shdr->sh_type);
if (shtype!=SHT_SYMTAB && shtype!=SHT_DYNSYM)
error(50,lf->pathname,tabname,lf->objname); /* illegal type */
symtab = (struct Elf64_Sym *)((uint8_t *)ehdr + read64(be,shdr->sh_offset));
elf_check_offset(lf,tabname,symtab,read64(be,shdr->sh_size));
return symtab;
}
static void elf64_section(struct GlobalVars *gv,struct Elf64_Ehdr *ehdr,
struct ObjectUnit *ou,struct Elf64_Shdr *shdr,
int shndx,char *shstrtab)
/* create a new section */
{
bool be = (ehdr->e_ident[EI_DATA] == ELFDATA2MSB);
struct Section *s;
if (s = elf_add_section(gv,ou,
shstrtab+read32(be,shdr->sh_name),
(uint8_t *)ehdr+read64(be,shdr->sh_offset),
read64(be,shdr->sh_size),
read32(be,shdr->sh_type),
read64(be,shdr->sh_flags),
shiftcnt(read64(be,shdr->sh_addralign)))) {
s->link = read32(be,shdr->sh_link); /* save link for later use */
s->id = shndx; /* use section header index for identification */
}
}
static void elf64_symbols(struct GlobalVars *gv,struct Elf64_Ehdr *ehdr,
struct ObjectUnit *ou,struct Elf64_Shdr *shdr)
/* convert ELF symbol definitions into internal format */
{
bool be = (ehdr->e_ident[EI_DATA] == ELFDATA2MSB);
struct LinkFile *lf = ou->lnkfile;
uint8_t *data = (uint8_t *)ehdr + read64(be,shdr->sh_offset);
unsigned long entsize = read64(be,shdr->sh_entsize);
int nsyms = (int)(read64(be,shdr->sh_size) / (uint64_t)entsize);
char *strtab = elf64_strtab(lf,ehdr,read32(be,shdr->sh_link));
elf_check_offset(lf,"symbol",data,read64(be,shdr->sh_size));
/* read ELF xdef symbols and convert to internal format */
while (--nsyms > 0) {
struct Elf64_Sym *elfsym;
char *symname;
elfsym = (struct Elf64_Sym *)(data += entsize);
symname = strtab + read32(be,elfsym->st_name);
if (symname<(char *)lf->data || symname>(char *)lf->data+lf->length)
error(127,lf->pathname,read32(be,elfsym->st_name),lf->objname);
elf_add_symbol(gv,ou,symname,
(read32(be,shdr->sh_type)==SHT_DYNSYM) ? SYMF_SHLIB : 0,
read16(be,elfsym->st_shndx),
read32(be,shdr->sh_type),
ELF64_ST_TYPE(*elfsym->st_info),
ELF64_ST_BIND(*elfsym->st_info),
read64(be,elfsym->st_value),
read64(be,elfsym->st_size));
}
}
static void elf64_dynrefs(struct GlobalVars *gv,struct Elf64_Ehdr *ehdr,
struct ObjectUnit *ou,struct Elf64_Shdr *shdr,
bool be,
uint8_t (*reloc_elf2vlink)(uint8_t,struct RelocInsert *))
/* Find all relocs in a shared object which refer to an undefined symbol. */
{
uint8_t *data = (uint8_t *)ehdr + read64(be,shdr->sh_offset);
unsigned long entsize = read64(be,shdr->sh_entsize);
uint32_t symndx = read32(be,shdr->sh_link);
int nrelocs = (int)(read64(be,shdr->sh_size) / (uint64_t)entsize);
struct LinkFile *lf = ou->lnkfile;
struct Section *sec;
struct Reloc *r;
elf_check_offset(lf,"reloc",data,read64(be,shdr->sh_size));
/* just put all xrefs into the first section of the shared object */
sec = abs_section(ou);
for (; nrelocs; nrelocs--,data+=entsize) {
struct Elf64_Rela *elfrel = (struct Elf64_Rela *)data;
struct Elf64_Shdr *symhdr = elf64_shdr(lf,ehdr,symndx);
struct Elf64_Sym *sym = elf64_symtab(lf,ehdr,symndx) +
ELF64_R_SYM(read64(be,elfrel->r_info));
uint32_t shndx = (uint32_t)read16(be,sym->st_shndx);
struct RelocInsert ri;
uint8_t rtype;
if (shndx == SHN_UNDEF || shndx == SHN_COMMON) {
memset(&ri,0,sizeof(struct RelocInsert));
rtype = reloc_elf2vlink(ELF64_R_TYPE(read64(be,elfrel->r_info)),&ri);
r = newreloc(gv,sec,elf64_strtab(lf,ehdr,read32(be,symhdr->sh_link))
+ read32(be,sym->st_name),
NULL,0,(unsigned long)read64(be,elfrel->r_offset),rtype,0);
addreloc_ri(sec,r,&ri);
/* referenced symbol is weak? */
if (ELF64_ST_BIND(*sym->st_info)==STB_WEAK)
r->flags |= RELF_WEAK;
}
}
}
static void elf64_reloc(struct GlobalVars *gv,struct Elf64_Ehdr *ehdr,
struct ObjectUnit *ou,struct Elf64_Shdr *shdr,
char *shstrtab,bool be,
uint8_t (*reloc_elf2vlink)(uint8_t,struct RelocInsert *))
/* Read ELF64 relocations, which are relative to a defined symbol, into
the section's reloc-list. If the symbol is undefined, create an
external reference on it, with the supplied relocation type. */
{
uint8_t *data = (uint8_t *)ehdr + read64(be,shdr->sh_offset);
bool is_rela = read32(be,shdr->sh_type) == SHT_RELA;
unsigned long entsize = read64(be,shdr->sh_entsize);
uint32_t symndx = read32(be,shdr->sh_link);
int nrelocs = (int)(read64(be,shdr->sh_size) / (uint64_t)entsize);
char *sec_name = shstrtab + read32(be,shdr->sh_name);
struct LinkFile *lf = ou->lnkfile;
struct Section *sec;
if (gv->strip_symbols>=STRIP_DEBUG &&
(!strncmp(sec_name,".rel.debug",10) ||
!strncmp(sec_name,".rel.stab",9) ||
!strncmp(sec_name,".rela.debug",11) ||
!strncmp(sec_name,".rela.stab",10)))
return; /* ignore debugging sections when -S or -s is given */
elf_check_offset(lf,"reloc",data,read64(be,shdr->sh_size));
if (!(sec = find_sect_id(ou,read32(be,shdr->sh_info)))) {
/* a section with this index doesn't exist! */
error(52,lf->pathname,shstrtab + read32(be,shdr->sh_name),
getobjname(ou),(int)read32(be,shdr->sh_info));
}
for (; nrelocs; nrelocs--,data+=entsize) {
struct Elf64_Rela *elfrel = (struct Elf64_Rela *)data;
struct Elf64_Shdr *symhdr = elf64_shdr(lf,ehdr,symndx);
struct Elf64_Sym *sym = elf64_symtab(lf,ehdr,symndx) +
ELF64_R_SYM(read64(be,elfrel->r_info));
uint64_t offs = read64(be,elfrel->r_offset);
uint32_t shndx = (uint32_t)read16(be,sym->st_shndx);
char *xrefname = NULL;
struct Section *relsec=NULL;
struct Reloc *r;
struct RelocInsert ri;
lword a;
uint8_t rtype;
memset(&ri,0,sizeof(struct RelocInsert));
rtype = reloc_elf2vlink(ELF64_R_TYPE(read64(be,elfrel->r_info)),&ri);
/* if addend is not defined in Reloc, read it directly from the section */
if (is_rela)
a = (lword)read64(be,elfrel->r_addend);
else
a = readsection(gv,rtype,sec->data,offs,&ri);
if (shndx == SHN_UNDEF || shndx == SHN_COMMON ||
ELF64_ST_BIND(*sym->st_info) == STB_WEAK) {
/* undefined, common or weak symbol - create external reference */
xrefname = elf64_strtab(lf,ehdr,read32(be,symhdr->sh_link)) +
read32(be,sym->st_name);
relsec = NULL;
}
else if (ELF64_ST_TYPE(*sym->st_info) == STT_SECTION) {
/* a normal relocation, with an offset relative to a section base */
relsec = find_sect_id(ou,shndx);
}
else if (ELF64_ST_TYPE(*sym->st_info)<STT_SECTION && shndx<SHN_ABS) {
/* relocations, which are relative to a known symbol */
relsec = find_sect_id(ou,shndx);
a += (lword)read64(be,sym->st_value);
}
else
ierror("elf64_reloc(): %s (%s): Only relocations which are relative "
"to a section, function or object are supported "
"(sym=%s, ST_TYPE=%d)",lf->pathname,lf->objname,
elf64_strtab(lf,ehdr,read32(be,symhdr->sh_link)) +
read32(be,sym->st_name),
ELF64_ST_TYPE(*sym->st_info));
r = newreloc(gv,sec,xrefname,relsec,0,(unsigned long)offs,rtype,a);
addreloc_ri(sec,r,&ri);
if (xrefname!=NULL && ELF64_ST_BIND(*sym->st_info)==STB_WEAK)
r->flags |= RELF_WEAK; /* referenced symbol is weak */
/* make sure that section data reflects this addend for other formats */
if (is_rela)
writesection(gv,sec->data,offs,r,a);
}
}
static void elf64_stabs(struct GlobalVars *gv,struct LinkFile *lf,
struct Elf64_Ehdr *ehdr,struct ObjectUnit *ou)
/* find .stabstr belonging to .stab, convert everything (including
.rela.stab) into internal format and delete *.stab* afterwards. */
{
#if 0 /* @@@ stabs */
static const char *fn = "elf64_stabs";
static const char *stabname = "stab";
bool be = (ehdr->e_ident[EI_DATA] == ELFDATA2MSB);
struct Section *stabsec;
if (stabsec = find_sect_name(ou,".stab")) {
char *strtab = elf64_strtab(lf,ehdr,stabsec->link);
struct nlist64 *nlst = (struct nlist32 *)stabsec->data;
long nlstlen = (long)stabsec->size;
while (nlstlen >= sizeof(struct nlist64)) {
/* next compilation unit: */
/* read number of nlist records and size of string table */
int cnt = (int)read16(be,&nlst->n_desc);
uint32_t strtabsize = read32(be,&nlst->n_value);
uint32_t funstart = 0; /* start address of last function definition */
struct Section *funsec = NULL;
nlst++;
nlstlen -= sizeof(struct nlist64);
while (cnt--) {
struct Reloc *r;
struct Section *relsec;
char *name;
uint64_t val;
if (nlstlen < sizeof(struct nlist64))
error(118,lf->pathname,stabname,lf->objname); /* malformatted */
if (nlst->n_strx)
name = strtab + read32(be,&nlst->n_strx);
else
name = NULL;
switch (nlst->n_type & N_TYPE) {
case N_TEXT:
case N_DATA:
case N_BSS:
if (r = findreloc(stabsec,
(uint8_t *)&nlst->n_value - stabsec->data)) {
if (r->rtype!=R_ABS || r->insert->bsiz!=32)
ierror("%s: Bad .stab relocation",fn);
relsec = r->relocsect.ptr;
val = (uint64_t)r->addend;
break;
}
default:
relsec = NULL;
val = read64(be,&nlst->n_value);
break;
}
switch (nlst->n_type) {
case N_FUN:
if (nlst->n_strx) {
if (relsec) { /* function start is always relocatable */
funsec = relsec;
funstart = val;
}
#if 0 /* @@@ N_FUN without a label in n_value seems legal? */
else
ierror("%s: N_FUN without relocatable address",fn);
#endif
}
else { /* no name marks function end, still relative */
relsec = funsec;
val += funstart;
}
break;
case N_SLINE:
if (relsec == NULL) {
relsec = funsec;
val += funstart;
}
break;
}
addstabs(ou,relsec,name,nlst->n_type,nlst->n_other,
(int16_t)read16(be,&nlst->n_desc),val);
nlst++;
nlstlen -= sizeof(struct nlist64);
}
strtab += strtabsize;
}
if (nlstlen)
error(118,lf->pathname,stabname,lf->objname); /* ignoring junk */
/* remove .stab from this object unit - will be recreated later */
remnode(&stabsec->n);
}
#endif
}
void elf64_parse(struct GlobalVars *gv,struct LinkFile *lf,
struct Elf64_Ehdr *ehdr,
uint8_t (*reloc_elf2vlink)(uint8_t,struct RelocInsert *))
/* parses a complete ELF file and converts into vlink-internal format */
{
static const char *fn = "elf64_parse(): ";
bool be = (ehdr->e_ident[EI_DATA] == ELFDATA2MSB);
struct ObjectUnit *u;
struct Elf64_Shdr *shdr;
uint16_t i,num_shdr,dynstr_idx,dynsym_idx;
char *shstrtab;
struct Elf64_Dyn *dyn;
shstrtab = elf64_shstrtab(lf,ehdr);
u = create_objunit(gv,lf,lf->objname);
switch (read16(be,ehdr->e_type)) {
case ET_REL: /* relocatable object file */
if (read16(be,ehdr->e_phnum) > 0)
error(47,lf->pathname,lf->objname); /* ignoring program hdr. tab */
num_shdr = read16(be,ehdr->e_shnum);
/* create vlink sections */
for (i=1; i<num_shdr; i++) {
shdr = elf64_shdr(lf,ehdr,i);
switch (read32(be,shdr->sh_type)) {
case SHT_PROGBITS:
case SHT_NOBITS:
case SHT_NOTE:
/* create a new section */
elf64_section(gv,ehdr,u,shdr,i,shstrtab);
default:
break;
}
}
/* parse the other section headers */
for (i=1; i<num_shdr; i++) {
shdr = elf64_shdr(lf,ehdr,i);
switch (read32(be,shdr->sh_type)) {
case SHT_NULL:
case SHT_STRTAB:
case SHT_NOTE:
case SHT_PROGBITS:
case SHT_NOBITS:
break;
case SHT_SYMTAB:
elf64_symbols(gv,ehdr,u,shdr); /* symbol definitions */
break;
case SHT_REL:
case SHT_RELA:
elf64_reloc(gv,ehdr,u,shdr,shstrtab,be,reloc_elf2vlink);
break;
default:
/* section header type not needed in relocatable objects */
error(48,lf->pathname,read32(be,shdr->sh_type),lf->objname);
break;
}
}
elf64_stabs(gv,lf,ehdr,u); /* convert .stab into internal format */
break;
case ET_DYN: /* shared object file */
dyn = NULL;
dynstr_idx = dynsym_idx = 0;
num_shdr = read16(be,ehdr->e_shnum);
/* create vlink sections */
for (i=1; i<num_shdr; i++) {
shdr = elf64_shdr(lf,ehdr,i);
switch (read32(be,shdr->sh_type)) {
case SHT_DYNAMIC:
/* remember pointer to .dynamic section contents */
dyn = (struct Elf64_Dyn *)((uint8_t *)ehdr
+ read64(be,shdr->sh_offset));
break;
case SHT_DYNSYM:
dynsym_idx = i;
break;
case SHT_PROGBITS:
case SHT_NOBITS:
/* create a new section */
elf64_section(gv,ehdr,u,shdr,i,shstrtab);
default:
break;
}
}
/* parse the other section headers */
for (i=1; i<num_shdr; i++) {
shdr = elf64_shdr(lf,ehdr,i);
switch (read32(be,shdr->sh_type)) {
case SHT_NULL:
case SHT_STRTAB:
case SHT_NOTE:
case SHT_PROGBITS:
case SHT_NOBITS:
case SHT_HASH:
case SHT_DYNAMIC:
case SHT_SYMTAB:
break;
case SHT_DYNSYM:
dynstr_idx = read32(be,shdr->sh_link);
elf64_symbols(gv,ehdr,u,shdr); /* symbol definitions */
break;
case SHT_REL:
case SHT_RELA:
if (fff[gv->dest_format]->flags & FFF_DYN_RESOLVE_ALL) {
/* The dynamic link editor is limited, so we even have to
resolve references from the shared object at link time.
But only those which are linked to .dynsym. */
if (read32(be,shdr->sh_link) == dynsym_idx)
elf64_dynrefs(gv,ehdr,u,shdr,be,reloc_elf2vlink);
}
break;
default:
/* section header type not needed in shared objects */
error(60,lf->pathname,read32(be,shdr->sh_type),lf->objname);
break;
}
}
if (dynstr_idx!=0 && dyn!=NULL) {
/* set ObjectUnit's objname to the SONAME of the shared object */
uint64_t tag;
shdr = elf64_shdr(lf,ehdr,dynstr_idx); /* .dynstr */
while (tag = read64(be,dyn->d_tag)) {
if (tag == DT_SONAME) {
u->objname = (char *)ehdr + read64(be,shdr->sh_offset)
+ read64(be,dyn->d_un.d_val);
break;
}
dyn++;
}
}
break;
case ET_EXEC: /* executable file */
/* @@@ */
ierror("%s%s: Executables are currently not supported",fn,lf->pathname);
break;
default:
error(41,lf->pathname,lf->objname); /* illegal fmt./file corrupted */
break;
}
/* add new object unit to the appropriate list */
add_objunit(gv,u,FALSE);
}
/*****************************************************************/
/* Link ELF */
/*****************************************************************/
static void elf64_initsym(void *p,uint32_t nameoff,uint64_t value,
uint64_t size,uint8_t bind,uint8_t type,
uint16_t shndx,bool be)
{
struct Elf64_Sym *s = (struct Elf64_Sym *)p;
write32(be,s->st_name,nameoff);
write64(be,s->st_value,value);
write64(be,s->st_size,size);
s->st_info[0] = ELF64_ST_INFO(bind,type);
s->st_other[0] = 0;
write16(be,s->st_shndx,shndx);
}
static void elf64_initreloc(void *p,uint64_t offset,uint64_t addend,
uint32_t symidx,uint32_t type,bool be)
{
struct Elf64_Rela *r = (struct Elf64_Rela *)p;
write64(be,r->r_offset,offset);
write64(be,r->r_addend,addend);
write64(be,r->r_info,ELF64_R_INFO((uint64_t)symidx,(uint64_t)type));
}
void elf64_initdynlink(struct GlobalVars *gv)
{
elf_initsymtabs(sizeof(struct Elf64_Sym),elf64_initsym);
dynamic = elf_initdynlink(gv);
}
struct Symbol *elf64_pltgotentry(struct GlobalVars *gv,struct Section *sec,
DynArg a,uint8_t entrysymtype,
unsigned long offsadd,unsigned long sizeadd,
int etype)
/* Make a table entry for indirectly accessing a location from an external
symbol definition (GOT_ENTRY/PLT_ENTRY) or a local relocation (GOT_LOCAL).
The entry has a size of offsadd bytes, while the table section sec will
become sizeadd bytes larger per entry. */
{
bool relaflag = gv->reloctab_format == RTAB_ADDEND;
return elf_pltgotentry(gv,sec,a,entrysymtype,offsadd,sizeadd,etype,relaflag,
relaflag ?
sizeof(struct Elf64_Rela) : sizeof(struct Elf64_Rel),
64);
}
struct Symbol *elf64_bssentry(struct GlobalVars *gv,const char *secname,
struct Symbol *xdef)
/* Allocate space for a copy-object in a .bss or .sbss section and create
a R_COPY relocation to the original symbol in the shared object. */
{
bool relaflag = gv->reloctab_format == RTAB_ADDEND;
return elf_bssentry(gv,secname,xdef,relaflag,relaflag ?
sizeof(struct Elf64_Rela) : sizeof(struct Elf64_Rel),
64);
}
void elf64_dynamicentry(struct GlobalVars *gv,uint64_t tag,uint64_t val,
struct Section *relsec)
/* store another entry into the .dynamic section, make new relocation with
relsec in value-field, when nonzero */
{
if (dynamic) {
bool be = elf_endianness == _BIG_ENDIAN_;
struct Elf64_Dyn dyn;
unsigned long offs = dynamic->size;
write64(be,dyn.d_tag,tag);
write64(be,dyn.d_un.d_val,val);
dynamic->data = re_alloc(dynamic->data,
dynamic->size+sizeof(struct Elf64_Dyn));
memcpy(dynamic->data+offs,&dyn,sizeof(struct Elf64_Dyn));
dynamic->size += sizeof(struct Elf64_Dyn);
if (relsec) {
/* we need a 64-bit R_ABS relocation for d_val */
struct Reloc *r;
int o = offsetof(struct Elf64_Dyn,d_un);
r = newreloc(gv,dynamic,NULL,relsec,0,offs+o,R_ABS,(lword)val);
r->flags |= RELF_INTERNAL; /* just for calculating the address */
addreloc(dynamic,r,0,64,-1);
}
}
else
ierror("elf64_dynamicentry(): .dynamic was never created");
}
static void elf64_makehash(struct GlobalVars *gv)
/* Allocate and populate .hash section. */
{
bool be = elf_endianness == _BIG_ENDIAN_;
size_t nsyms = elfdsymlist.nextindex;
size_t nbuckets = elf_num_buckets(nsyms);
struct Section *hashsec = find_sect_name(gv->dynobj,hash_name);
if (hashsec) {
struct SymbolNode *sn;
uint64_t *hdata;
/* .hash layout: nbuckets, nsyms, [buckets], [sym-indexes] */
hashsec->size = (2 + nbuckets + nsyms) * sizeof(uint64_t);
hashsec->data = alloczero(hashsec->size);
hdata = (uint64_t *)hashsec->data;
write64(be,&hdata[0],nbuckets);
write64(be,&hdata[1],nsyms);
for (sn=(struct SymbolNode *)elfdsymlist.l.first;
sn->n.next!=NULL; sn=(struct SymbolNode *)sn->n.next) {
uint64_t *i = &hdata[2 + elf_hash(sn->name) % nbuckets];
uint64_t j;
while (j = read64(be,i))
i = &hdata[2 + nbuckets + j];
write64(be,i,sn->index);
}
}
else
ierror("elf64_makehash(): no %s",hash_name);
}
void elf64_dyncreate(struct GlobalVars *gv,const char *pltgot_name)
/* generate .hash, populate .dynstr and .dynamic, allocate .dynsym,
so that all sections have a valid size for the address calculation */
{
const char *fn = "elf64_dyncreate():";
struct Section *dynstr,*dynsym,*pltgot;
struct LibPath *lpn;
if (gv->dynobj == NULL)
ierror("%s no dynobj",fn);
/* write SONAME and RPATHs */
if (gv->soname && gv->dest_sharedobj)
elf64_dynamicentry(gv,DT_SONAME,elf_adddynstr(gv->soname),NULL);
for (lpn=(struct LibPath *)gv->rpaths.first; lpn->n.next!=NULL;
lpn=(struct LibPath *)lpn->n.next) {
elf64_dynamicentry(gv,DT_RPATH,elf_adddynstr(lpn->path),NULL);
}
/* generate .hash section */
elf64_makehash(gv);
/* allocate and populate .dynstr section */
if (dynstr = find_sect_name(gv->dynobj,dynstr_name)) {
dynstr->size = elfdstrlist.nextindex;
dynstr->data = alloc(dynstr->size);
elf_putstrtab(dynstr->data,&elfdstrlist);
}
else
ierror("%s %s missing",fn,dynstr_name);
/* allocate .dynsym section - populate it later, when addresses are fixed */
if (dynsym = find_sect_name(gv->dynobj,dynsym_name)) {
dynsym->size = elfdsymlist.nextindex * sizeof(struct Elf64_Sym);
dynsym->data = alloc(dynsym->size);
}
else
ierror("%s %s missing",fn,dynsym_name);
/* finish .dynamic section */
elf64_dynamicentry(gv,DT_HASH,0,find_sect_name(gv->dynobj,hash_name));
elf64_dynamicentry(gv,DT_STRTAB,0,dynstr);
elf64_dynamicentry(gv,DT_SYMTAB,0,dynsym);
elf64_dynamicentry(gv,DT_STRSZ,dynstr->size,NULL);
elf64_dynamicentry(gv,DT_SYMENT,sizeof(struct Elf64_Sym),NULL);
elf64_dynamicentry(gv,DT_DEBUG,0,NULL); /* needed? */
/* do we have a .plt or .got section (target dependent) */
if (pltgot = find_sect_name(gv->dynobj,pltgot_name)) {
elf64_dynamicentry(gv,DT_PLTGOT,0,pltgot);
}
/* do we have .plt relocations? */
if (elfpltrelocs) {
elf64_dynamicentry(gv,DT_PLTRELSZ,elfpltrelocs->size,NULL);
elf64_dynamicentry(gv,DT_PLTREL,
gv->reloctab_format==RTAB_ADDEND?DT_RELA:DT_REL,
NULL);
elf64_dynamicentry(gv,DT_JMPREL,0,elfpltrelocs);
}
/* do we have any other dynamic relocations? */
if (elfdynrelocs) {
if (gv->reloctab_format == RTAB_ADDEND) {
elf64_dynamicentry(gv,DT_RELA,0,elfdynrelocs);
elf64_dynamicentry(gv,DT_RELASZ,elfdynrelocs->size,NULL);
elf64_dynamicentry(gv,DT_RELAENT,sizeof(struct Elf64_Rela),NULL);
}
else {
elf64_dynamicentry(gv,DT_REL,0,elfdynrelocs);
elf64_dynamicentry(gv,DT_RELSZ,elfdynrelocs->size,NULL);
elf64_dynamicentry(gv,DT_RELENT,sizeof(struct Elf64_Rel),NULL);
}
}
/* end tag */
elf64_dynamicentry(gv,DT_NULL,0,NULL);
}
/*****************************************************************/
/* Write ELF */
/*****************************************************************/
unsigned long elf64_headersize(struct GlobalVars *gv)
{
return sizeof(struct Elf64_Ehdr) +
elf_numsegments(gv) * sizeof(struct Elf64_Phdr);
}
static void elf64_header(FILE *f,uint16_t type,uint16_t mach,uint64_t entry,
uint64_t phoff,uint64_t shoff,uint32_t flags,
uint16_t phnum,uint16_t shnum,uint16_t shstrndx,
bool be)
/* write 64-bit ELF header */
{
struct Elf64_Ehdr eh;
memset(&eh,0,sizeof(struct Elf64_Ehdr));
elf_ident(&eh,be,ELFCLASS64,type,mach);
write64(be,eh.e_entry,entry);
write64(be,eh.e_phoff,phoff);
write64(be,eh.e_shoff,shoff);
write32(be,eh.e_flags,flags);
write16(be,eh.e_ehsize,sizeof(struct Elf64_Ehdr));
write16(be,eh.e_phentsize,phnum ? sizeof(struct Elf64_Phdr):0);
write16(be,eh.e_phnum,phnum);
write16(be,eh.e_shentsize,shnum ? sizeof(struct Elf64_Shdr):0);
write16(be,eh.e_shnum,shnum);
write16(be,eh.e_shstrndx,shstrndx);
fwritex(f,&eh,sizeof(struct Elf64_Ehdr));
}
static struct ShdrNode *elf64_newshdr(void)
{
struct ShdrNode *s = alloczero(sizeof(struct ShdrNode));
addtail(&shdrlist,&s->n);
++elfshdridx;
return s;
}
static struct ShdrNode *elf64_addshdr(uint32_t name,uint32_t type,
uint64_t flags,uint64_t addr,
uint64_t offset,uint64_t size,
uint32_t link,uint32_t info,
uint64_t align,uint64_t entsize,bool be)
{
struct ShdrNode *shn = elf64_newshdr();
write32(be,shn->s.sh_name,name);
write32(be,shn->s.sh_type,type);
write64(be,shn->s.sh_flags,flags);
write64(be,shn->s.sh_addr,addr);
write64(be,shn->s.sh_offset,offset);
write64(be,shn->s.sh_size,size);
write32(be,shn->s.sh_link,link);
write32(be,shn->s.sh_info,info);
write64(be,shn->s.sh_addralign,align);
write64(be,shn->s.sh_entsize,entsize);
return shn;
}
static void elf64_writephdrs(struct GlobalVars *gv,FILE *f)
/* write 32-bit ELF Program Header (PHDR) */
{
bool be = elf_endianness == _BIG_ENDIAN_;
long gapsize = elf_file_hdr_gap;
struct Elf64_Phdr phdr;
struct Phdr *p;
for (p=gv->phdrlist; p; p=p->next) {
if (p->flags & PHDR_USED) {
if (p->start!=ADDR_NONE && p->start_vma!=ADDR_NONE) {
write32(be,phdr.p_type,p->type);
write64(be,phdr.p_offset,p->offset);
write64(be,phdr.p_vaddr,p->start_vma);
write64(be,phdr.p_paddr,p->start);
write64(be,phdr.p_filesz,p->file_end - p->start);
write64(be,phdr.p_memsz,p->mem_end - p->start);
write32(be,phdr.p_flags,p->flags & PHDR_PFMASK);
write64(be,phdr.p_align,1LL<<p->alignment);
fwritex(f,&phdr,sizeof(struct Elf64_Phdr));
}
else
gapsize += sizeof(struct Elf64_Phdr);
}
}
fwritegap(gv,f,gapsize); /* gap at the end, for unused PHDRs */
}
static void elf64_writeshdrs(struct GlobalVars *gv,FILE *f,
uint32_t reloffset,uint32_t stabndx)
/* write all section headers */
{
const char *fn = "elf64_writeshdrs():";
bool be = elf_endianness == _BIG_ENDIAN_;
struct LinkedSection *ls;
struct ShdrNode *shn;
uint32_t type;
while (shn = (struct ShdrNode *)remhead(&shdrlist)) {
type = read32(be,shn->s.sh_type);
/* handle REL and RELA sections */
if (type == SHT_RELA || type == SHT_REL) {
if (read64(be,shn->s.sh_flags) & SHF_ALLOC) {
/* allocated, so probably dynamic relocs: link to .dynsym */
if (ls = find_lnksec(gv,dynsym_name,0,0,0,0))
write32(be,shn->s.sh_link,(uint32_t)ls->index);
else
ierror("%s %s",fn,dynsym_name);
if (read32(be,shn->s.sh_info) != 0) {
/* link to .plt requested in info field */
if (ls = find_lnksec(gv,plt_name,0,0,0,0))
write32(be,shn->s.sh_info,(uint32_t)ls->index);
else
ierror("%s %s",fn,plt_name);
}
}
else {
/* patch correct sh_offset and sh_link for reloc header */
write64(be,shn->s.sh_offset,
read64(be,shn->s.sh_offset)+(uint64_t)reloffset);
write32(be,shn->s.sh_link,stabndx);
}
}
/* handle HASH sections, which need a .dynsym link */
else if (type == SHT_HASH) {
if (ls = find_lnksec(gv,dynsym_name,0,0,0,0))
write32(be,shn->s.sh_link,(uint32_t)ls->index);
else
ierror("%s %s",fn,dynsym_name);
}
/* handle DYNAMIC and DYNSYM sections */
else if (type==SHT_DYNAMIC || type==SHT_DYNSYM) {
/* write .dynstr link */
if (ls = find_lnksec(gv,dynstr_name,0,0,0,0))
write32(be,shn->s.sh_link,(uint32_t)ls->index);
else
ierror("%s %s",fn,dynstr_name);
if (type == SHT_DYNSYM) {
write32(be,shn->s.sh_info,1); /* @@ FIXME! number of local symbols */
}
}
fwritex(f,&shn->s,sizeof(struct Elf64_Shdr));
}
}
static void elf64_sec2shdr(struct LinkedSection *ls,bool bss,uint64_t f)
{
struct ShdrNode *shn;
uint32_t type = bss ? SHT_NOBITS : SHT_PROGBITS;
uint32_t info = 0;
uint32_t entsize = 0;
if (!strncmp(ls->name,note_name,strlen(note_name)))
type = SHT_NOTE;
else if (!strncmp(ls->name,".rela",5)) {
type = SHT_RELA;
entsize = sizeof(struct Elf64_Rela);
}
else if (!strncmp(ls->name,".rel",4)) {
type = SHT_REL;
entsize = sizeof(struct Elf64_Rel);
}
else if (!strcmp(ls->name,hash_name)) {
type = SHT_HASH;
entsize = sizeof(uint32_t);
}
else if (!strcmp(ls->name,dynsym_name)) {
type = SHT_DYNSYM;
entsize = sizeof(struct Elf64_Sym);
}
else if (!strcmp(ls->name,dyn_name)) {
type = SHT_DYNAMIC;
entsize = sizeof(struct Elf64_Dyn);
}
else if (!strcmp(ls->name,dynstr_name))
type = SHT_STRTAB;
else if (!strncmp(ls->name,got_name,strlen(got_name)))
entsize = sizeof(uint64_t);
if (!strcmp(ls->name,pltrel_name[0]) || !strcmp(ls->name,pltrel_name[1]))
info = ~0; /* request .plt index in info field for .rel(a).plt */
shn = elf64_addshdr(elf_addshdrstr(ls->name),type,f,ls->base,
(uint64_t)elfoffset,ls->size,0,info,1LL<<ls->alignment,
(uint64_t)entsize,elf_endianness);
if (stabdebugidx && !strcmp(ls->name,".stab"))
stabshdr = shn; /* patch sh_link field for .stabstr later */
}
static void elf64_addrelocs(struct GlobalVars *gv,
uint8_t (*reloc_vlink2elf)(struct Reloc *))
/* creates relocations for all sections */
{
bool be = elf_endianness == _BIG_ENDIAN_;
struct LinkedSection *ls;
struct Reloc *rel;
uint32_t sroffs=0,roffs=0;
for (ls=(struct LinkedSection *)gv->lnksec.first;