/* $NetBSD: ppc_reloc.c,v 1.10 2001/09/10 06:09:41 mycroft Exp $ */ /*- * SPDX-License-Identifier: BSD-2-Clause * * Copyright (C) 1998 Tsubai Masanari * 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. */ #include #include #include #include #include #include #include #include #include #include #include "debug.h" #include "rtld.h" #define _ppc_ha(x) ((((u_int32_t)(x) & 0x8000) ? \ ((u_int32_t)(x) + 0x10000) : (u_int32_t)(x)) >> 16) #define _ppc_la(x) ((u_int32_t)(x) & 0xffff) #define min(a,b) (((a) < (b)) ? (a) : (b)) #define max(a,b) (((a) > (b)) ? (a) : (b)) #define PLT_EXTENDED_BEGIN (1 << 13) #define JMPTAB_BASE(N) (18 + N*2 + ((N > PLT_EXTENDED_BEGIN) ? \ (N - PLT_EXTENDED_BEGIN)*2 : 0)) void _rtld_bind_secureplt_start(void); /* * Process the R_PPC_COPY relocations */ int do_copy_relocations(Obj_Entry *dstobj) { const Elf_Rela *relalim; const Elf_Rela *rela; /* * COPY relocs are invalid outside of the main program */ assert(dstobj->mainprog); relalim = (const Elf_Rela *)((const char *) dstobj->rela + dstobj->relasize); for (rela = dstobj->rela; rela < relalim; rela++) { void *dstaddr; const Elf_Sym *dstsym; const char *name; size_t size; const void *srcaddr; const Elf_Sym *srcsym = NULL; const Obj_Entry *srcobj, *defobj; SymLook req; int res; if (ELF_R_TYPE(rela->r_info) != R_PPC_COPY) { continue; } dstaddr = (void *)(dstobj->relocbase + rela->r_offset); dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); name = dstobj->strtab + dstsym->st_name; size = dstsym->st_size; symlook_init(&req, name); req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info)); req.flags = SYMLOOK_EARLY; for (srcobj = globallist_next(dstobj); srcobj != NULL; srcobj = globallist_next(srcobj)) { res = symlook_obj(&req, srcobj); if (res == 0) { srcsym = req.sym_out; defobj = req.defobj_out; break; } } if (srcobj == NULL) { _rtld_error("Undefined symbol \"%s\" " " referenced from COPY" " relocation in %s", name, dstobj->path); return (-1); } srcaddr = (const void *)(defobj->relocbase+srcsym->st_value); memcpy(dstaddr, srcaddr, size); dbg("copy_reloc: src=%p,dst=%p,size=%d\n",srcaddr,dstaddr,size); } return (0); } /* * Perform early relocation of the run-time linker image */ void reloc_non_plt_self(Elf_Dyn *dynp, Elf_Addr relocbase) { const Elf_Rela *rela = NULL, *relalim; Elf_Addr relasz = 0; Elf_Addr *where; /* * Extract the rela/relasz values from the dynamic section */ 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; } } /* * Relocate these values */ relalim = (const Elf_Rela *)((const char *)rela + relasz); for (; rela < relalim; rela++) { where = (Elf_Addr *)(relocbase + rela->r_offset); *where = (Elf_Addr)(relocbase + rela->r_addend); } } /* * Relocate a non-PLT object with addend. */ static int reloc_nonplt_object(Obj_Entry *obj_rtld __unused, Obj_Entry *obj, const Elf_Rela *rela, SymCache *cache, int flags, RtldLockState *lockstate) { const Elf_Sym *def = NULL; const Obj_Entry *defobj; Elf_Addr *where, symval = 0; /* * First, resolve symbol for relocations which * reference symbols. */ switch (ELF_R_TYPE(rela->r_info)) { case R_PPC_UADDR32: /* word32 S + A */ case R_PPC_ADDR32: case R_PPC_GLOB_DAT: /* word32 S + A */ case R_PPC_DTPMOD32: case R_PPC_TPREL32: case R_PPC_DTPREL32: def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, flags, cache, lockstate); if (def == NULL) { return (-1); } /* * If symbol is IFUNC, only perform relocation * when caller allowed it by passing * SYMLOOK_IFUNC flag. Skip the relocations * otherwise. * * Also error out in case IFUNC relocations * are specified for TLS, which cannot be * usefully interpreted. */ if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { switch (ELF_R_TYPE(rela->r_info)) { case R_PPC_UADDR32: case R_PPC_ADDR32: case R_PPC_GLOB_DAT: if ((flags & SYMLOOK_IFUNC) == 0) { dbg("Non-PLT reference to IFUNC found!"); obj->non_plt_gnu_ifunc = true; return (0); } symval = (Elf_Addr)rtld_resolve_ifunc( defobj, def); break; default: _rtld_error("%s: IFUNC for TLS reloc", obj->path); return (-1); } } else { if ((flags & SYMLOOK_IFUNC) != 0) return (0); symval = (Elf_Addr)defobj->relocbase + def->st_value; } break; default: if ((flags & SYMLOOK_IFUNC) != 0) return (0); } where = (Elf_Addr *)(obj->relocbase + rela->r_offset); switch (ELF_R_TYPE(rela->r_info)) { case R_PPC_NONE: break; case R_PPC_UADDR32: case R_PPC_ADDR32: case R_PPC_GLOB_DAT: /* Don't issue write if unnecessary; avoid COW page fault */ if (*where != symval + rela->r_addend) { *where = symval + rela->r_addend; } break; case R_PPC_DTPMOD32: *where = (Elf_Addr) defobj->tlsindex; break; case R_PPC_TPREL32: /* * We lazily allocate offsets for static TLS as we * see the first relocation that references the * TLS block. This allows us to support (small * amounts of) static TLS in dynamically loaded * modules. If we run out of space, we generate an * error. */ if (!defobj->tls_static) { if (!allocate_tls_offset( __DECONST(Obj_Entry *, defobj))) { _rtld_error("%s: No space available for static " "Thread Local Storage", obj->path); return (-1); } } *(Elf_Addr **)where = *where * sizeof(Elf_Addr) + (Elf_Addr *)(def->st_value + rela->r_addend + defobj->tlsoffset - TLS_TP_OFFSET - TLS_TCB_SIZE); break; case R_PPC_DTPREL32: *where += (Elf_Addr)(def->st_value + rela->r_addend - TLS_DTV_OFFSET); break; case R_PPC_RELATIVE: /* word32 B + A */ symval = (Elf_Addr)(obj->relocbase + rela->r_addend); /* As above, don't issue write unnecessarily */ if (*where != symval) { *where = symval; } break; case R_PPC_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->mainprog) { _rtld_error("%s: Unexpected R_COPY " " relocation in shared library", obj->path); return (-1); } break; case R_PPC_IRELATIVE: /* * These will be handled by reloc_iresolve(). */ obj->irelative = true; break; case R_PPC_JMP_SLOT: /* * These will be handled by the plt/jmpslot routines */ break; default: _rtld_error("%s: Unsupported relocation type %d" " in non-PLT relocations\n", obj->path, ELF_R_TYPE(rela->r_info)); return (-1); } return (0); } /* * Process non-PLT relocations */ int reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags, RtldLockState *lockstate) { const Elf_Rela *relalim; const Elf_Rela *rela; const Elf_Phdr *phdr; SymCache *cache; int r = -1; /* * The dynamic loader may be called from a thread, we have * limited amounts of stack available so we cannot use alloca(). */ if (obj != obj_rtld) { cache = calloc(obj->dynsymcount, sizeof(SymCache)); /* No need to check for NULL here */ } else cache = NULL; /* * From the SVR4 PPC ABI: * "The PowerPC family uses only the Elf32_Rela relocation * entries with explicit addends." */ relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize); for (rela = obj->rela; rela < relalim; rela++) { if (reloc_nonplt_object(obj_rtld, obj, rela, cache, flags, lockstate) < 0) goto done; } r = 0; done: if (cache != NULL) free(cache); /* * Synchronize icache for executable segments in case we made * any changes. */ for (phdr = obj->phdr; (const char *)phdr < (const char *)obj->phdr + obj->phsize; phdr++) { if (phdr->p_type == PT_LOAD && (phdr->p_flags & PF_X) != 0) { __syncicache(obj->relocbase + phdr->p_vaddr, phdr->p_memsz); } } return (r); } /* * Initialise a PLT slot to the resolving trampoline */ static int reloc_plt_object(Obj_Entry *obj, const Elf_Rela *rela) { Elf_Word *where = (Elf_Word *)(obj->relocbase + rela->r_offset); Elf_Addr *pltresolve, *pltlongresolve, *jmptab; Elf_Addr distance; int N = obj->pltrelasize / sizeof(Elf_Rela); int reloff; reloff = rela - obj->pltrela; if (reloff < 0) return (-1); if (obj->gotptr != NULL) { *where += (Elf_Addr)obj->relocbase; return (0); } pltlongresolve = obj->pltgot + 5; pltresolve = pltlongresolve + 5; distance = (Elf_Addr)pltresolve - (Elf_Addr)(where + 1); dbg(" reloc_plt_object: where=%p,pltres=%p,reloff=%x,distance=%x", (void *)where, (void *)pltresolve, reloff, distance); if (reloff < PLT_EXTENDED_BEGIN) { /* li r11,reloff */ /* b pltresolve */ where[0] = 0x39600000 | reloff; where[1] = 0x48000000 | (distance & 0x03fffffc); } else { jmptab = obj->pltgot + JMPTAB_BASE(N); jmptab[reloff] = (u_int)pltlongresolve; /* lis r11,jmptab[reloff]@ha */ /* lwzu r12,jmptab[reloff]@l(r11) */ /* mtctr r12 */ /* bctr */ where[0] = 0x3d600000 | _ppc_ha(&jmptab[reloff]); where[1] = 0x858b0000 | _ppc_la(&jmptab[reloff]); where[2] = 0x7d8903a6; where[3] = 0x4e800420; } /* * The icache will be sync'd in reloc_plt, which is called * after all the slots have been updated */ return (0); } /* * Process the PLT relocations. */ int reloc_plt(Obj_Entry *obj, int flags __unused, RtldLockState *lockstate __unused) { const Elf_Rela *relalim; const Elf_Rela *rela; int N = obj->pltrelasize / sizeof(Elf_Rela); if (obj->pltrelasize != 0) { relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); for (rela = obj->pltrela; rela < relalim; rela++) { if (ELF_R_TYPE(rela->r_info) == R_PPC_IRELATIVE) { dbg("ABI violation - found IRELATIVE in the PLT."); obj->irelative = true; continue; } /* * PowerPC(64) .rela.plt is composed of an array of * R_PPC_JMP_SLOT relocations. Unlike other platforms, * this is the ONLY relocation type that is valid here. */ assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT); if (reloc_plt_object(obj, rela) < 0) { return (-1); } } } /* * Sync the icache for the byte range represented by the * trampoline routines and call slots. */ if (obj->pltgot != NULL && obj->gotptr == NULL) __syncicache(obj->pltgot, JMPTAB_BASE(N)*4); return (0); } /* * LD_BIND_NOW was set - force relocation for all jump slots */ int reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate) { const Obj_Entry *defobj; const Elf_Rela *relalim; const Elf_Rela *rela; const Elf_Sym *def; Elf_Addr *where; Elf_Addr target; relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); for (rela = obj->pltrela; rela < relalim; rela++) { /* This isn't actually a jump slot, ignore it. */ if (ELF_R_TYPE(rela->r_info) == R_PPC_IRELATIVE) continue; assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT); where = (Elf_Addr *)(obj->relocbase + rela->r_offset); def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, SYMLOOK_IN_PLT | flags, NULL, lockstate); if (def == NULL) { dbg("reloc_jmpslots: sym not found"); return (-1); } target = (Elf_Addr)(defobj->relocbase + def->st_value); if (def == &sym_zero) { /* Zero undefined weak symbols */ *where = 0; } else { if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { /* LD_BIND_NOW, ifunc in shared lib.*/ obj->gnu_ifunc = true; continue; } reloc_jmpslot(where, target, defobj, obj, (const Elf_Rel *) rela); } } obj->jmpslots_done = true; return (0); } /* * Update the value of a PLT jump slot. */ Elf_Addr reloc_jmpslot(Elf_Addr *wherep, Elf_Addr target, const Obj_Entry *defobj __unused, const Obj_Entry *obj, const Elf_Rel *rel) { Elf_Addr offset; const Elf_Rela *rela = (const Elf_Rela *) rel; dbg(" reloc_jmpslot: where=%p, target=%p", (void *)wherep, (void *)target); if (ld_bind_not) goto out; /* * Process Secure-PLT. */ if (obj->gotptr != NULL) { assert(wherep >= (Elf_Word *)obj->pltgot); assert(wherep < (Elf_Word *)obj->pltgot + obj->pltrelasize); if (*wherep != target) *wherep = target; goto out; } /* * BSS-PLT optimization: * Branch directly to the target if it is within +/- 32Mb, * otherwise go indirectly via the pltcall trampoline call and * jump table. */ offset = target - (Elf_Addr)wherep; if (abs((int)offset) < 32*1024*1024) { /* inside 32MB? */ /* * At the PLT entry pointed at by `wherep', construct * a direct transfer to the now fully resolved function * address. */ /* b value # branch directly */ *wherep = 0x48000000 | (offset & 0x03fffffc); __syncicache(wherep, 4); } else { Elf_Addr *pltcall, *jmptab; int distance; int N = obj->pltrelasize / sizeof(Elf_Rela); int reloff = rela - obj->pltrela; if (reloff < 0) return (-1); pltcall = obj->pltgot; dbg(" reloc_jmpslot: indir, reloff=%x, N=%x\n", reloff, N); jmptab = obj->pltgot + JMPTAB_BASE(N); jmptab[reloff] = target; mb(); /* Order jmptab update before next changes */ if (reloff < PLT_EXTENDED_BEGIN) { /* for extended PLT entries, we keep the old code */ distance = (Elf_Addr)pltcall - (Elf_Addr)(wherep + 1); /* li r11,reloff */ /* b pltcall # use indirect pltcall routine */ /* first instruction same as before */ wherep[1] = 0x48000000 | (distance & 0x03fffffc); __syncicache(wherep, 8); } } out: return (target); } int reloc_iresolve(Obj_Entry *obj, struct Struct_RtldLockState *lockstate) { /* * Since PLT slots on PowerPC are always R_PPC_JMP_SLOT, * R_PPC_IRELATIVE is in RELA. */ const Elf_Rela *relalim; const Elf_Rela *rela; Elf_Addr *where, target, *ptr; if (!obj->irelative) return (0); relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize); for (rela = obj->rela; rela < relalim; rela++) { if (ELF_R_TYPE(rela->r_info) == R_PPC_IRELATIVE) { ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend); where = (Elf_Addr *)(obj->relocbase + rela->r_offset); lock_release(rtld_bind_lock, lockstate); target = call_ifunc_resolver(ptr); wlock_acquire(rtld_bind_lock, lockstate); *where = target; } } /* * XXX Remove me when lld is fixed! * LLD currently makes illegal relocations in the PLT. */ relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); for (rela = obj->pltrela; rela < relalim; rela++) { if (ELF_R_TYPE(rela->r_info) == R_PPC_IRELATIVE) { ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend); where = (Elf_Addr *)(obj->relocbase + rela->r_offset); lock_release(rtld_bind_lock, lockstate); target = call_ifunc_resolver(ptr); wlock_acquire(rtld_bind_lock, lockstate); *where = target; } } obj->irelative = false; return (0); } int reloc_iresolve_nonplt(Obj_Entry *obj __unused, struct Struct_RtldLockState *lockstate __unused) { return (0); } int reloc_gnu_ifunc(Obj_Entry *obj __unused, int flags __unused, struct Struct_RtldLockState *lockstate __unused) { const Elf_Rela *relalim; const Elf_Rela *rela; Elf_Addr *where, target; const Elf_Sym *def; const Obj_Entry *defobj; if (!obj->gnu_ifunc) return (0); relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); for (rela = obj->pltrela; rela < relalim; rela++) { if (ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT) { where = (Elf_Addr *)(obj->relocbase + rela->r_offset); def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, SYMLOOK_IN_PLT | flags, NULL, lockstate); if (def == NULL) return (-1); if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC) continue; lock_release(rtld_bind_lock, lockstate); target = (Elf_Addr)rtld_resolve_ifunc(defobj, def); wlock_acquire(rtld_bind_lock, lockstate); reloc_jmpslot(where, target, defobj, obj, (const Elf_Rel *)rela); } } obj->gnu_ifunc = false; return (0); } /* * Setup the plt glue routines. */ #define PLTCALL_SIZE 20 #define PLTLONGRESOLVE_SIZE 20 #define PLTRESOLVE_SIZE 24 void init_pltgot(Obj_Entry *obj) { Elf_Word *pltcall, *pltresolve, *pltlongresolve; Elf_Word *jmptab; int N = obj->pltrelasize / sizeof(Elf_Rela); pltcall = obj->pltgot; if (pltcall == NULL) { return; } /* Handle Secure-PLT first, if applicable. */ 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]); return; } /* * From the SVR4 PPC ABI: * * 'The first 18 words (72 bytes) of the PLT are reserved for * use by the dynamic linker. * ... * 'If the executable or shared object requires N procedure * linkage table entries, the link editor shall reserve 3*N * words (12*N bytes) following the 18 reserved words. The * first 2*N of these words are the procedure linkage table * entries themselves. The static linker directs calls to bytes * (72 + (i-1)*8), for i between 1 and N inclusive. The remaining * N words (4*N bytes) are reserved for use by the dynamic linker.' */ /* * Copy the absolute-call assembler stub into the first part of * the reserved PLT area. */ memcpy(pltcall, _rtld_powerpc_pltcall, PLTCALL_SIZE); /* * Determine the address of the jumptable, which is the dyn-linker * reserved area after the call cells. Write the absolute address * of the jumptable into the absolute-call assembler code so it * can determine this address. */ jmptab = obj->pltgot + JMPTAB_BASE(N); pltcall[1] |= _ppc_ha(jmptab); /* addis 11,11,jmptab@ha */ pltcall[2] |= _ppc_la(jmptab); /* lwz 11,jmptab@l(11) */ /* * Skip down 20 bytes into the initial reserved area and copy * in the standard resolving assembler call. Into this assembler, * insert the absolute address of the _rtld_bind_start routine * and the address of the relocation object. * * We place pltlongresolve first, so it can fix up its arguments * and then fall through to the regular PLT resolver. */ pltlongresolve = obj->pltgot + 5; memcpy(pltlongresolve, _rtld_powerpc_pltlongresolve, PLTLONGRESOLVE_SIZE); pltlongresolve[0] |= _ppc_ha(jmptab); /* lis 12,jmptab@ha */ pltlongresolve[1] |= _ppc_la(jmptab); /* addi 12,12,jmptab@l */ pltresolve = pltlongresolve + PLTLONGRESOLVE_SIZE/sizeof(uint32_t); memcpy(pltresolve, _rtld_powerpc_pltresolve, PLTRESOLVE_SIZE); pltresolve[0] |= _ppc_ha(_rtld_bind_start); pltresolve[1] |= _ppc_la(_rtld_bind_start); pltresolve[3] |= _ppc_ha(obj); pltresolve[4] |= _ppc_la(obj); /* * The icache will be sync'd in reloc_plt, which is called * after all the slots have been updated */ } /* * 32 bit cpu feature flag fields. */ u_long cpu_features; u_long cpu_features2; void powerpc_abi_variant_hook(Elf_Auxinfo** aux_info) { /* * Since aux_info[] is easier to work with than aux, go ahead and * initialize cpu_features / cpu_features2. */ cpu_features = -1UL; cpu_features2 = -1UL; if (aux_info[AT_HWCAP] != NULL) cpu_features = aux_info[AT_HWCAP]->a_un.a_val; if (aux_info[AT_HWCAP2] != NULL) cpu_features2 = aux_info[AT_HWCAP2]->a_un.a_val; } void ifunc_init(Elf_Auxinfo aux_info[__min_size(AT_COUNT)] __unused) { } void allocate_initial_tls(Obj_Entry *list) { /* * Fix the size of the static TLS block by using the maximum * offset allocated so far and adding a bit for dynamic modules to * use. */ tls_static_space = tls_last_offset + tls_last_size + RTLD_STATIC_TLS_EXTRA; _tcb_set(allocate_tls(list, NULL, TLS_TCB_SIZE, TLS_TCB_ALIGN)); } void* __tls_get_addr(tls_index* ti) { uintptr_t **dtvp; char *p; dtvp = &_tcb_get()->tcb_dtv; p = tls_get_addr_common(dtvp, ti->ti_module, ti->ti_offset); return (p + TLS_DTV_OFFSET); }