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Calculate relocation base for the main object, and apply the relocation

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adjustment for all virtual addresses encoded into the ELF structures of
it. PIE binary could and should be loaded at non-zero mapbase.

For sym_zero pseudosymbol used as a return value from find_symdef()
for undefined weak symbols, st_value also should be adjusted, since
_rtld_bind corrects symbol values by relocbase.

Discussed with:	bz
Reviewed by:	kan
Tested by:	bz (i386, amd64), bsam (linux)
MFC after:	some time
This commit is contained in:
Konstantin Belousov 2009-10-10 15:27:10 +00:00
parent 47d81c1b70
commit dec4912e62
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=197931
1 changed files with 15 additions and 14 deletions
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29
libexec/rtld-elf/rtld.c
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@ -474,6 +474,7 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
/* Initialize a fake symbol for resolving undefined weak references. */
sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
sym_zero.st_shndx = SHN_UNDEF;
sym_zero.st_value = -(uintptr_t)obj_main->relocbase;
if (!libmap_disable)
libmap_disable = (bool)lm_init(libmap_override);
@ -990,27 +991,27 @@ digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
int nsegs = 0;
obj = obj_new();
for (ph = phdr; ph < phlimit; ph++) {
if (ph->p_type != PT_PHDR)
continue;
obj->phdr = phdr;
obj->phsize = ph->p_memsz;
obj->relocbase = (caddr_t)phdr - ph->p_vaddr;
break;
}
for (ph = phdr; ph < phlimit; ph++) {
switch (ph->p_type) {
case PT_PHDR:
if ((const Elf_Phdr *)ph->p_vaddr != phdr) {
_rtld_error("%s: invalid PT_PHDR", path);
return NULL;
}
obj->phdr = (const Elf_Phdr *) ph->p_vaddr;
obj->phsize = ph->p_memsz;
break;
case PT_INTERP:
obj->interp = (const char *) ph->p_vaddr;
obj->interp = (const char *)(ph->p_vaddr + obj->relocbase);
break;
case PT_LOAD:
if (nsegs == 0) { /* First load segment */
obj->vaddrbase = trunc_page(ph->p_vaddr);
obj->mapbase = (caddr_t) obj->vaddrbase;
obj->relocbase = obj->mapbase - obj->vaddrbase;
obj->mapbase = obj->vaddrbase + obj->relocbase;
obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
obj->vaddrbase;
} else { /* Last load segment */
@ -1021,7 +1022,7 @@ digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
break;
case PT_DYNAMIC:
obj->dynamic = (const Elf_Dyn *) ph->p_vaddr;
obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
break;
case PT_TLS:
@ -1029,7 +1030,7 @@ digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
obj->tlssize = ph->p_memsz;
obj->tlsalign = ph->p_align;
obj->tlsinitsize = ph->p_filesz;
obj->tlsinit = (void*) ph->p_vaddr;
obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
break;
}
}