xref: /src/libexec/ld.elf_so/arch/x86_64/mdreloc.c

#include <sys/types.h>
#include <sys/mman.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <elf.h>

#include "debug.h"
#include "rtld.h"

extern Elf64_Addr _GLOBAL_OFFSET_TABLE_[];

int
_rtld_relocate_nonplt_object(Obj_Entry *obj, const Elf_RelA *rela, bool dodebug)
{
	Elf64_Addr *where64;
	Elf32_Addr *where32;
	const Elf_Sym *def;
	const Obj_Entry *defobj;
	Elf64_Addr tmp64;
	Elf32_Addr tmp32;

	where64 = (Elf64_Addr *)(obj->relocbase + rela->r_offset);
	where32 = (Elf32_Addr *)where64;

	switch (ELF_R_TYPE(rela->r_info)) {

	case R_TYPE(NONE):
		break;

	case R_TYPE(32):	/* word32 S + A, truncate */
	case R_TYPE(32S):	/* word32 S + A, signed truncate */
	case R_TYPE(GOT32):	/* word32 G + A (XXX can we see these?) */
		def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj,
		    &defobj, false);
		if (def == NULL)
			return -1;
		tmp32 = (Elf32_Addr)(u_long)(defobj->relocbase + def->st_value +
		    rela->r_addend);

		if (*where32 != tmp32)
			*where32 = tmp32;
		rdbg(dodebug, ("32/32S %s in %s --> %p in %s",
		    defobj->strtab + def->st_name, obj->path,
		    (void *)(unsigned long)*where32, defobj->path));
		break;
	case R_TYPE(64):	/* word64 S + A */
		def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj,
		    &defobj, false);
		if (def == NULL)
			return -1;

		tmp64 = (Elf64_Addr)(defobj->relocbase + def->st_value +
		    rela->r_addend);

		if (*where64 != tmp64)
			*where64 = tmp64;
		rdbg(dodebug, ("64 %s in %s --> %p in %s",
		    defobj->strtab + def->st_name, obj->path,
		    (void *)*where64, defobj->path));
		break;
	case R_TYPE(PC32):	/* word32 S + A - P */
		def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj,
		    &defobj, false);
		if (def == NULL)
			return -1;
		tmp32 = (Elf32_Addr)(u_long)(defobj->relocbase + def->st_value +
		    rela->r_addend - (Elf64_Addr)where64);
		if (*where32 != tmp32)
			*where32 = tmp32;
		rdbg(dodebug, ("PC32 %s in %s --> %p in %s",
		    defobj->strtab + def->st_name, obj->path,
		    (void *)(unsigned long)*where32, defobj->path));
		break;
	case R_TYPE(GLOB_DAT):	/* word64 S */
		def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj,
		    &defobj, false);
		if (def == NULL)
			return -1;

		tmp64 = (Elf64_Addr)(defobj->relocbase + def->st_value);

		if (*where64 != tmp64)
			*where64 = tmp64;
		rdbg(dodebug, ("64 %s in %s --> %p in %s",
		    defobj->strtab + def->st_name, obj->path,
		    (void *)*where64, defobj->path));
		break;
	case R_TYPE(RELATIVE):  /* word64 B + A */
		tmp64 = (Elf64_Addr)(obj->relocbase + rela->r_addend);
		if (*where64 != tmp64)
			*where64 = tmp64;
		rdbg(dodebug, ("RELATIVE in %s --> %p", obj->path,
		    (void *)*where64));
                break;

	case R_TYPE(COPY):
		rdbg(dodebug, ("COPY"));
		break;

	default:
		def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj,
		    &defobj, true);
		rdbg(dodebug, ("sym = %lu, type = %lu, offset = %p, "
		    "addend = %p, contents = %p, symbol = %s",
		    (u_long)ELF_R_SYM(rela->r_info),
		    (u_long)ELF_R_TYPE(rela->r_info),
		    (void *)rela->r_offset, (void *)rela->r_addend,
		    (void *)*where64,
		    def ? defobj->strtab + def->st_name : "??"));
		_rtld_error("%s: Unsupported relocation type %ld "
		    "in non-PLT relocations\n",
		    obj->path, (u_long) ELF_R_TYPE(rela->r_info));
		return -1;
	}
	return 0;
}



int
_rtld_relocate_plt_object(Obj_Entry *obj, const Elf_RelA *rela, caddr_t *addrp,
			  bool bind_now, bool dodebug)
{
	Elf32_Addr *where = (Elf32_Addr *)(obj->relocbase + rela->r_offset);
	Elf32_Addr new_value;

	/* Fully resolve procedure addresses now */

	if (bind_now || obj->pltgot == NULL) {
		const Elf_Sym  *def;
		const Obj_Entry *defobj;

		assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JUMP_SLOT));

		def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj,
		    &defobj, true);
		if (def == NULL)
			return -1;

		new_value = (Elf32_Addr)(u_long)
		    (defobj->relocbase + def->st_value + rela->r_addend);
		rdbg(dodebug, ("bind now %d/fixup in %s --> old=%p new=%p",
		    (int)bind_now,
		    defobj->strtab + def->st_name,
		    (void *)(u_long)*where, (void *)(u_long)new_value));
	} else {
		if (!obj->mainprog) {
			/* Just relocate the GOT slots pointing into the PLT */
			new_value = *where + (Elf32_Addr)(u_long)
			    obj->relocbase;
			rdbg(dodebug, ("fixup !main in %s --> %p", obj->path,
			    (void *)(unsigned long)*where));
		} else {
			return 0;
		}
	}
	/*
         * Since this page is probably copy-on-write, let's not write
         * it unless we really really have to.
         */
	if (*where != new_value)
		*where = new_value;
	if (addrp != NULL)
		*addrp = *(caddr_t *)(obj->relocbase + rela->r_offset) -
		    rela->r_addend;
	return 0;
}