Initial pass at supporting shared libraries on amd64. There are still
a few missing relocation types in amd64/reloc.c, but I have not found any of them in use yet. :-) Approved by: re (amd64/* blanket)
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b3aa27a531
commit
9783a12b34
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=115280
@ -48,7 +48,7 @@
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#include "rtld.h"
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/*
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* Process the special R_386_COPY relocations in the main program. These
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* Process the special R_X86_64_COPY relocations in the main program. These
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* copy data from a shared object into a region in the main program's BSS
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* segment.
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*
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@ -57,14 +57,14 @@
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int
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do_copy_relocations(Obj_Entry *dstobj)
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{
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const Elf_Rel *rellim;
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const Elf_Rel *rel;
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const Elf_Rela *relalim;
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const Elf_Rela *rela;
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assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */
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rellim = (const Elf_Rel *) ((caddr_t) dstobj->rel + dstobj->relsize);
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for (rel = dstobj->rel; rel < rellim; rel++) {
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if (ELF_R_TYPE(rel->r_info) == R_386_COPY) {
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relalim = (const Elf_Rela *) ((caddr_t) dstobj->rela + dstobj->relasize);
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for (rela = dstobj->rela; rela < relalim; rela++) {
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if (ELF_R_TYPE(rela->r_info) == R_X86_64_COPY) {
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void *dstaddr;
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const Elf_Sym *dstsym;
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const char *name;
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@ -74,8 +74,8 @@ do_copy_relocations(Obj_Entry *dstobj)
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const Elf_Sym *srcsym;
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Obj_Entry *srcobj;
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dstaddr = (void *) (dstobj->relocbase + rel->r_offset);
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dstsym = dstobj->symtab + ELF_R_SYM(rel->r_info);
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dstaddr = (void *) (dstobj->relocbase + rela->r_offset);
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dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info);
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name = dstobj->strtab + dstsym->st_name;
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hash = elf_hash(name);
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size = dstsym->st_size;
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@ -112,8 +112,8 @@ init_pltgot(Obj_Entry *obj)
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int
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reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
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{
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const Elf_Rel *rellim;
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const Elf_Rel *rel;
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const Elf_Rela *relalim;
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const Elf_Rela *rela;
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SymCache *cache;
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int bytes = obj->nchains * sizeof(SymCache);
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int r = -1;
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@ -126,30 +126,30 @@ reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
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if (cache == MAP_FAILED)
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cache = NULL;
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rellim = (const Elf_Rel *) ((caddr_t) obj->rel + obj->relsize);
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for (rel = obj->rel; rel < rellim; rel++) {
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Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
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relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize);
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for (rela = obj->rela; rela < relalim; rela++) {
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Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset);
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switch (ELF_R_TYPE(rel->r_info)) {
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switch (ELF_R_TYPE(rela->r_info)) {
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case R_386_NONE:
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case R_X86_64_NONE:
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break;
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case R_386_32:
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case R_X86_64_64:
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{
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
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false, cache);
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if (def == NULL)
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goto done;
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*where += (Elf_Addr) (defobj->relocbase + def->st_value);
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*where = (Elf_Addr) (defobj->relocbase + def->st_value + rela->r_addend);
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}
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break;
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case R_386_PC32:
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case R_X86_64_PC32:
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/*
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* I don't think the dynamic linker should ever see this
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* type of relocation. But the binutils-2.6 tools sometimes
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@ -159,18 +159,19 @@ reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
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false, cache);
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if (def == NULL)
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goto done;
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*where +=
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(Elf_Addr) (defobj->relocbase + def->st_value) -
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*where =
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(Elf_Addr) (defobj->relocbase + def->st_value + rela->r_addend) -
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(Elf_Addr) where;
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}
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break;
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/* missing: R_X86_64_GOT32 R_X86_64_PLT32 */
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case R_386_COPY:
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case R_X86_64_COPY:
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/*
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* These are deferred until all other relocations have
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* been done. All we do here is make sure that the COPY
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@ -178,18 +179,18 @@ reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
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* only in executable files.
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*/
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if (!obj->mainprog) {
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_rtld_error("%s: Unexpected R_386_COPY relocation"
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_rtld_error("%s: Unexpected R_X86_64_COPY relocation"
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" in shared library", obj->path);
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goto done;
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}
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break;
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case R_386_GLOB_DAT:
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case R_X86_64_GLOB_DAT:
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{
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
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false, cache);
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if (def == NULL)
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goto done;
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@ -198,14 +199,16 @@ reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
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}
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break;
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case R_386_RELATIVE:
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*where += (Elf_Addr) obj->relocbase;
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case R_X86_64_RELATIVE:
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*where = (Elf_Addr)(obj->relocbase + rela->r_addend);
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break;
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/* missing: R_X86_64_GOTPCREL, R_X86_64_32, R_X86_64_32S, R_X86_64_16, R_X86_64_PC16, R_X86_64_8, R_X86_64_PC8 */
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default:
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_rtld_error("%s: Unsupported relocation type %d"
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" in non-PLT relocations\n", obj->path,
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ELF_R_TYPE(rel->r_info));
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ELF_R_TYPE(rela->r_info));
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goto done;
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}
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}
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@ -220,17 +223,17 @@ reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
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int
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reloc_plt(Obj_Entry *obj)
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{
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const Elf_Rel *rellim;
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const Elf_Rel *rel;
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const Elf_Rela *relalim;
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const Elf_Rela *rela;
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rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
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for (rel = obj->pltrel; rel < rellim; rel++) {
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relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
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for (rela = obj->pltrela; rela < relalim; rela++) {
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Elf_Addr *where;
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assert(ELF_R_TYPE(rel->r_info) == R_386_JMP_SLOT);
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assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT);
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/* Relocate the GOT slot pointing into the PLT. */
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where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
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where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
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*where += (Elf_Addr)obj->relocbase;
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}
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return 0;
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@ -240,24 +243,24 @@ reloc_plt(Obj_Entry *obj)
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int
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reloc_jmpslots(Obj_Entry *obj)
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{
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const Elf_Rel *rellim;
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const Elf_Rel *rel;
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const Elf_Rela *relalim;
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const Elf_Rela *rela;
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if (obj->jmpslots_done)
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return 0;
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rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
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for (rel = obj->pltrel; rel < rellim; rel++) {
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relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
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for (rela = obj->pltrela; rela < relalim; rela++) {
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Elf_Addr *where, target;
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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assert(ELF_R_TYPE(rel->r_info) == R_386_JMP_SLOT);
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where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
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def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL);
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assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT);
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where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true, NULL);
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if (def == NULL)
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return -1;
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target = (Elf_Addr)(defobj->relocbase + def->st_value);
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reloc_jmpslot(where, target, defobj, obj, rel);
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target = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend);
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reloc_jmpslot(where, target, defobj, obj, (const Elf_Rel *)rela);
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}
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obj->jmpslots_done = true;
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return 0;
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@ -30,27 +30,24 @@
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.globl .rtld_start
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.type .rtld_start,@function
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.rtld_start:
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xorl %ebp,%ebp # Clear frame pointer for good form
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movl %esp,%eax # Save initial stack pointer
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subl $8,%esp # A place to store exit procedure addr
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movl %esp,%ebx # save address of exit proc
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movl %esp,%ecx # construct address of obj_main
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addl $4,%ecx
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pushl %ecx # Pass address of obj_main
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pushl %ebx # Pass address of exit proc
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pushl %eax # Pass initial stack pointer to rtld
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xorq %rbp,%rbp # Clear frame pointer for good form
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subq $16,%rsp # A place to store exit procedure addr
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movq %rdi,%r12
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movq %rsp,%rsi # save address of exit proc
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movq %rsp,%rdx # construct address of obj_main
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addq $8,%rdx
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call _rtld@PLT # Call rtld(sp); returns entry point
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addl $12,%esp # Remove arguments from stack
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popl %edx # Get exit procedure address
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addl $4,%esp # Ignore obj_main
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popq %rsi # Get exit procedure address
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addq $8,%rsp # Ignore obj_main
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movq %r12,%rdi # *ap
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/*
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* At this point, %eax contains the entry point of the main program, and
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* %edx contains a pointer to a termination function that should be
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* At this point, %rax contains the entry point of the main program, and
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* %rdx contains a pointer to a termination function that should be
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* registered with atexit(). (crt1.o registers it.)
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*/
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.globl .rtld_goto_main
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.rtld_goto_main: # This symbol exists just to make debugging easier.
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jmp *%eax # Enter main program
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jmp *%rax # Enter main program
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/*
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@ -63,26 +60,54 @@
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* We are careful to preserve all registers, even the the caller-save
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* registers. That is because this code may be invoked by low-level
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* assembly-language code that is not ABI-compliant.
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*
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* Stack map:
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* reloff 0x58
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* obj 0x50
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* rflags 0x48
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* rax 0x40
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* rdx 0x38
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* rcx 0x30
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* rsi 0x28
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* rdi 0x20
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* r8 0x18
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* r9 0x10
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* r10 0x8
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* r11 0x0
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*/
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.align 4
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.globl _rtld_bind_start
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.type _rtld_bind_start,@function
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_rtld_bind_start:
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pushf # Save eflags
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pushl %eax # Save %eax
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pushl %edx # Save %edx
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pushl %ecx # Save %ecx
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pushl 20(%esp) # Copy reloff argument
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pushl 20(%esp) # Copy obj argument
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pushfq # Save rflags
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pushq %rax # Save %rax
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pushq %rdx # Save %rdx
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pushq %rcx # Save %rcx
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pushq %rsi # Save %rsi
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pushq %rdi # Save %rdi
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pushq %r8 # Save %r8
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pushq %r9 # Save %r9
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pushq %r10 # Save %r10
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pushq %r11 # Save %r11
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movq 0x50(%rsp),%rdi # Fetch obj argument
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movq 0x58(%rsp),%rsi # Fetch reloff argument
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leaq (%rsi,%rsi,2),%rsi # multiply by 3
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leaq (,%rsi,8),%rsi # now 8, for 24 (sizeof Elf_Rela)
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call _rtld_bind@PLT # Transfer control to the binder
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/* Now %eax contains the entry point of the function being called. */
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/* Now %rax contains the entry point of the function being called. */
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addl $8,%esp # Discard binder arguments
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movl %eax,20(%esp) # Store target over obj argument
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popl %ecx # Restore %ecx
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popl %edx # Restore %edx
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popl %eax # Restore %eax
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popf # Restore eflags
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leal 4(%esp),%esp # Discard reloff, do not change eflags
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movq %rax,0x58(%rsp) # Store target over reloff argument
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popq %r11 # Restore %r11
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popq %r10 # Restore %r10
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popq %r9 # Restore %r9
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popq %r8 # Restore %r8
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popq %rdi # Restore %rdi
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popq %rsi # Restore %rsi
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popq %rcx # Restore %rcx
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popq %rdx # Restore %rdx
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popq %rax # Restore %rax
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popfq # Restore rflags
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leaq 8(%rsp),%rsp # Discard obj, do not change rflags
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ret # "Return" to target address
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