/* $NetBSD: ppc_reloc.c,v 1.66 2024/11/30 01:04:05 christos Exp $ */ /*- * Copyright (C) 1998 Tsubai Masanari * Portions copyright 2002 Charles M. Hannum * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /* * Power ELF relocations. * * Reference: * * Power Architecture(R) 32-bit * Application Binary Interface Supplement 1.0 - Linux(R) * http://web.archive.org/web/20120608163845/https://www.power.org/resources/downloads/Power-Arch-32-bit-ABI-supp-1.0-Linux.pdf * * 64-bit PowerPC ELF Application Binary Interface Supplement 1.9 * https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.pdf */ #include #ifndef lint __RCSID("$NetBSD: ppc_reloc.c,v 1.66 2024/11/30 01:04:05 christos Exp $"); #endif /* not lint */ #include #include #include #include #include #include #include "debug.h" #include "rtld.h" #include void _rtld_powerpc_pltcall(Elf_Word); void _rtld_powerpc_pltresolve(Elf_Word, Elf_Word); #define __u64(x) ((uint64_t)(x)) #define __u32(x) ((uint32_t)(x)) #define __ha48 __u64(0xffffffff8000) #define __ha32 __u64(0xffff8000) #define __ha16 __u32(0x8000) #define __ha(x,n) ((((x) >> (n)) + (((x) & __ha##n) == __ha##n)) & 0xffff) #define __hi(x,n) (((x) >> (n)) & 0xffff) #ifdef __LP64 #define highesta(x) __ha(__u64(x), 48) #define highest(x) __hi(__u64(x), 48) #define higher(x) __ha(__u64(x), 32) #define higher(x) __hi(__u64(x), 32) #endif #define ha(x) __ha(__u32(x), 16) #define hi(x) __hi(__u32(x), 16) #define lo(x) (__u32(x) & 0xffff) #ifdef _LP64 /* function descriptor for _rtld_bind_start */ extern const uint64_t _rtld_bind_start[3]; #else void _rtld_bind_bssplt_start(void); void _rtld_bind_secureplt_start(void); #endif Elf_Addr _rtld_bind(const Obj_Entry *, Elf_Word); void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); static int _rtld_relocate_plt_object(const Obj_Entry *, const Elf_Rela *, int, Elf_Addr *); /* * The PPC32 PLT format consists of three sections: * (1) The "pltcall" and "pltresolve" glue code. This is always 18 words. * (2) The code part of the PLT entries. There are 2 words per entry for * up to 8192 entries, then 4 words per entry for any additional entries. * (3) The data part of the PLT entries, comprising a jump table. * This section is half the size of the second section (ie. 1 or 2 words * per entry). */ void _rtld_setup_pltgot(const Obj_Entry *obj) { #ifdef _LP64 /* * For powerpc64, just copy the function descriptor to pltgot[0]. */ if (obj->pltgot != NULL) { obj->pltgot[0] = (Elf_Addr) _rtld_bind_start[0]; obj->pltgot[1] = (Elf_Addr) _rtld_bind_start[1]; obj->pltgot[2] = (Elf_Addr) obj; } #else /* * Secure-PLT is much more sane. */ if (obj->gotptr != NULL) { obj->gotptr[1] = (Elf_Addr) _rtld_bind_secureplt_start; obj->gotptr[2] = (Elf_Addr) obj; dbg(("obj %s secure-plt gotptr=%p start=%p obj=%p", obj->path, obj->gotptr, (void *) obj->gotptr[1], (void *) obj->gotptr[2])); } else { /* * Setup the plt glue routines (for bss-plt). */ #define BSSPLTCALL_SIZE 20 #define BSSPLTRESOLVE_SIZE 24 Elf_Word *pltcall, *pltresolve; Elf_Word *jmptab; int N = obj->pltrelalim - obj->pltrela; /* Entries beyond 8192 take twice as much space. */ if (N > 8192) N += N-8192; dbg(("obj %s bss-plt pltgot=%p jmptab=%u start=%p obj=%p", obj->path, obj->pltgot, 18 + N * 2, _rtld_bind_bssplt_start, obj)); pltcall = obj->pltgot; jmptab = pltcall + 18 + N * 2; memcpy(pltcall, _rtld_powerpc_pltcall, BSSPLTCALL_SIZE); pltcall[1] |= ha(jmptab); pltcall[2] |= lo(jmptab); pltresolve = obj->pltgot + 8; memcpy(pltresolve, _rtld_powerpc_pltresolve, BSSPLTRESOLVE_SIZE); pltresolve[0] |= ha(_rtld_bind_bssplt_start); pltresolve[1] |= lo(_rtld_bind_bssplt_start); pltresolve[3] |= ha(obj); pltresolve[4] |= lo(obj); /* * Invalidate the icache for only the code part of the PLT * (and not the jump table at the end). */ __syncicache(pltcall, (char *)jmptab - (char *)pltcall); } #endif } void _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) { const Elf_Rela *rela = 0, *relalim; Elf_Addr relasz = 0; Elf_Addr *where; for (; dynp->d_tag != DT_NULL; dynp++) { switch (dynp->d_tag) { case DT_RELA: rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr); break; case DT_RELASZ: relasz = dynp->d_un.d_val; break; } } relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz); for (; rela < relalim; rela++) { where = (Elf_Addr *)(relocbase + rela->r_offset); *where = (Elf_Addr)(relocbase + rela->r_addend); } } int _rtld_relocate_nonplt_objects(Obj_Entry *obj) { const Elf_Rela *rela; const Elf_Sym *def = NULL; const Obj_Entry *defobj = NULL; unsigned long last_symnum = ULONG_MAX; for (rela = obj->rela; rela < obj->relalim; rela++) { Elf_Addr *where; Elf_Addr tmp; unsigned long symnum; where = (Elf_Addr *)(obj->relocbase + rela->r_offset); symnum = ELF_R_SYM(rela->r_info); switch (ELF_R_TYPE(rela->r_info)) { #ifdef _LP64 case R_TYPE(ADDR64): /*
S + A */ #else case R_TYPE(ADDR32): /*
S + A */ case R_TYPE(UADDR32): /*
S + A */ #endif case R_TYPE(GLOB_DAT): /*
S + A */ case R_TYPE(ADDR16_LO): case R_TYPE(ADDR16_HI): case R_TYPE(ADDR16_HA): case R_TYPE(DTPMOD): case R_TYPE(DTPREL): case R_TYPE(TPREL): if (last_symnum != symnum) { last_symnum = symnum; def = _rtld_find_symdef(symnum, obj, &defobj, false); if (def == NULL) return -1; } break; default: break; } switch (ELF_R_TYPE(rela->r_info)) { #if 1 /* XXX Should not be necessary. */ case R_TYPE(JMP_SLOT): #endif case R_TYPE(NONE): break; #ifdef _LP64 case R_TYPE(ADDR64): /*
S + A */ #else case R_TYPE(ADDR32): /*
S + A */ case R_TYPE(UADDR32): /*
S + A */ #endif case R_TYPE(GLOB_DAT): /*
S + A */ tmp = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend); if (*where != tmp) *where = tmp; rdbg(("32/GLOB_DAT %s in %s --> %p in %s", obj->strtab + obj->symtab[symnum].st_name, obj->path, (void *)*where, defobj->path)); break; /* * Recent GNU ld does not resolve ADDR16_{LO,HI,HA} if * the reloc is in a writable section and the symbol * is not already referenced from text. */ case R_TYPE(ADDR16_LO): { tmp = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend); uint16_t tmp16 = lo(tmp); uint16_t *where16 = (uint16_t *)where; if (*where16 != tmp16) *where16 = tmp16; rdbg(("ADDR16_LO %s in %s --> #lo(%p) = 0x%x in %s", obj->strtab + obj->symtab[symnum].st_name, obj->path, (void *)tmp, tmp16, defobj->path)); break; } case R_TYPE(ADDR16_HI): case R_TYPE(ADDR16_HA): { tmp = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend); uint16_t tmp16 = hi(tmp); if (ELF_R_TYPE(rela->r_info) == R_TYPE(ADDR16_HA) && (tmp & __ha16)) ++tmp16; /* adjust to ha(tmp) */ uint16_t *where16 = (uint16_t *)where; if (*where16 != tmp16) *where16 = tmp16; rdbg(("ADDR16_H%c %s in %s --> #h%c(%p) = 0x%x in %s", (ELF_R_TYPE(rela->r_info) == R_TYPE(ADDR16_HI) ? 'I' : 'A'), obj->strtab + obj->symtab[symnum].st_name, obj->path, (ELF_R_TYPE(rela->r_info) == R_TYPE(ADDR16_HI) ? 'i' : 'a'), (void *)tmp, tmp16, defobj->path)); break; } case R_TYPE(RELATIVE): /*
B + A */ *where = (Elf_Addr)(obj->relocbase + rela->r_addend); rdbg(("RELATIVE in %s --> %p", obj->path, (void *)*where)); break; case R_TYPE(COPY): /* * These are deferred until all other relocations have * been done. All we do here is make sure that the * COPY relocation is not in a shared library. They * are allowed only in executable files. */ if (obj->isdynamic) { _rtld_error( "%s: Unexpected R_COPY relocation in shared library", obj->path); return -1; } rdbg(("COPY (avoid in main)")); break; case R_TYPE(DTPMOD): *where = (Elf_Addr)defobj->tlsindex; rdbg(("DTPMOD32 %s in %s --> %p in %s", obj->strtab + obj->symtab[symnum].st_name, obj->path, (void *)*where, defobj->path)); break; case R_TYPE(DTPREL): *where = (Elf_Addr)(def->st_value + rela->r_addend - TLS_DTV_OFFSET); rdbg(("DTPREL32 %s in %s --> %p in %s", obj->strtab + obj->symtab[symnum].st_name, obj->path, (void *)*where, defobj->path)); break; case R_TYPE(TPREL): if (!defobj->tls_static && _rtld_tls_offset_allocate(__UNCONST(defobj))) return -1; *where = (Elf_Addr)(def->st_value + rela->r_addend + defobj->tlsoffset - TLS_TP_OFFSET); rdbg(("TPREL32 %s in %s --> %p in %s", obj->strtab + obj->symtab[symnum].st_name, obj->path, (void *)*where, defobj->path)); break; case R_TYPE(IRELATIVE): /* IFUNC relocations are handled in _rtld_call_ifunc */ if (obj->ifunc_remaining_nonplt == 0) { obj->ifunc_remaining_nonplt = obj->relalim - rela; } break; default: rdbg(("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 *)*where, obj->strtab + obj->symtab[symnum].st_name)); _rtld_error("%s: Unsupported relocation type %ld " "in non-PLT relocations", obj->path, (u_long) ELF_R_TYPE(rela->r_info)); return -1; } } return 0; } int _rtld_relocate_plt_lazy(Obj_Entry *obj) { #ifdef _LP64 /* * For PowerPC64, the plt stubs handle an empty function descriptor * so there's nothing to do. */ /* XXX ifunc support */ #else Elf_Addr * const pltresolve = obj->pltgot + 8; const Elf_Rela *rela; for (rela = obj->pltrelalim; rela-- > obj->pltrela;) { size_t reloff = rela - obj->pltrela; Elf_Word *where = (Elf_Word *)(obj->relocbase + rela->r_offset); assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT) || ELF_R_TYPE(rela->r_info) == R_TYPE(IRELATIVE)); if (ELF_R_TYPE(rela->r_info) == R_TYPE(IRELATIVE)) { /* No ifunc support for old-style insecure PLT. */ assert(obj->gotptr != NULL); obj->ifunc_remaining = obj->pltrelalim - rela; } if (obj->gotptr != NULL) { /* * For now, simply treat then as relative. */ *where += (Elf_Addr)obj->relocbase; } else { int distance; if (reloff < 32768) { /* li r11,reloff */ *where++ = 0x39600000 | reloff; } else { /* lis r11,ha(reloff) */ /* addi r11,lo(reloff) */ *where++ = 0x3d600000 | ha(reloff); *where++ = 0x396b0000 | lo(reloff); } /* b pltresolve */ distance = (Elf_Addr)pltresolve - (Elf_Addr)where; *where++ = 0x48000000 | (distance & 0x03fffffc); /* * Icache invalidation is not done for each entry here * because we sync the entire code part of the PLT once * in _rtld_setup_pltgot() after all the entries have been * initialized. */ /* __syncicache(where - 3, 12); */ } } #endif /* !_LP64 */ return 0; } static int _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, int reloff, Elf_Addr *tp) { Elf_Word *where = (Elf_Word *)(obj->relocbase + rela->r_offset); Elf_Addr value; const Elf_Sym *def; const Obj_Entry *defobj; unsigned long info = rela->r_info; assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); if (__predict_false(def == NULL)) return -1; if (__predict_false(def == &_rtld_sym_zero)) return 0; if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { if (tp == NULL) return 0; value = _rtld_resolve_ifunc(defobj, def); } else { value = (Elf_Addr)(defobj->relocbase + def->st_value); } rdbg(("bind now/fixup in %s --> new=%p", defobj->strtab + def->st_name, (void *)value)); #ifdef _LP64 /* * For PowerPC64 we simply replace the function descriptor in the * PLTGOT with the one from source object. */ assert(where >= (Elf_Word *)obj->pltgot); assert(where < (Elf_Word *)obj->pltgot + (obj->pltrelalim - obj->pltrela)); const Elf_Addr * const fdesc = (Elf_Addr *) value; where[0] = fdesc[0]; where[1] = fdesc[1]; where[2] = fdesc[2]; #else ptrdiff_t distance = value - (Elf_Addr)where; if (obj->gotptr != NULL) { /* * For Secure-PLT we simply replace the entry in GOT with the * address of the routine. */ assert(where >= (Elf_Word *)obj->pltgot); assert(where < (Elf_Word *)obj->pltgot + (obj->pltrelalim - obj->pltrela)); *where = value; } else if (labs(distance) < 32*1024*1024) { /* inside 32MB? */ /* b value # branch directly */ *where = 0x48000000 | (distance & 0x03fffffc); __syncicache(where, 4); } else { Elf_Addr *pltcall, *jmptab; int N = obj->pltrelalim - obj->pltrela; /* Entries beyond 8192 take twice as much space. */ if (N > 8192) N += N-8192; pltcall = obj->pltgot; jmptab = pltcall + 18 + N * 2; jmptab[reloff] = value; if (reloff < 32768) { /* li r11,reloff */ *where++ = 0x39600000 | reloff; } else { #ifdef notyet /* lis r11,ha(value) */ /* addi r11,lo(value) */ /* mtctr r11 */ /* bctr */ *where++ = 0x3d600000 | ha(value); *where++ = 0x396b0000 | lo(value); *where++ = 0x7d6903a6; *where++ = 0x4e800420; #else /* lis r11,ha(reloff) */ /* addi r11,lo(reloff) */ *where++ = 0x3d600000 | ha(reloff); *where++ = 0x396b0000 | lo(reloff); #endif } /* b pltcall */ distance = (Elf_Addr)pltcall - (Elf_Addr)where; *where++ = 0x48000000 | (distance & 0x03fffffc); __syncicache(where - 3, 12); } #endif /* _LP64 */ if (tp) *tp = value; return 0; } Elf_Addr _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) { const Elf_Rela *rela = obj->pltrela + reloff; Elf_Addr new_value; int err; new_value = 0; /* XXX gcc */ _rtld_shared_enter(); err = _rtld_relocate_plt_object(obj, rela, reloff, &new_value); if (err) _rtld_die(); _rtld_shared_exit(); #ifdef _LP64 return obj->glink; #else return new_value; #endif } int _rtld_relocate_plt_objects(const Obj_Entry *obj) { const Elf_Rela *rela; int reloff; for (rela = obj->pltrela, reloff = 0; rela < obj->pltrelalim; rela++, reloff++) { if (_rtld_relocate_plt_object(obj, rela, reloff, NULL) < 0) return -1; } return 0; }