395 lines
12 KiB
C
395 lines
12 KiB
C
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/* $NetBSD: mdreloc.c,v 1.44 2010/08/06 16:33:18 joerg Exp $ */
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/*-
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* Copyright (c) 1999, 2002 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Paul Kranenburg and by Charles M. Hannum.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__RCSID("$NetBSD: mdreloc.c,v 1.44 2010/08/06 16:33:18 joerg Exp $");
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#endif /* not lint */
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "rtldenv.h"
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#include "debug.h"
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#include "rtld.h"
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/*
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* The following table holds for each relocation type:
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* - the width in bits of the memory location the relocation
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* applies to (not currently used)
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* - the number of bits the relocation value must be shifted to the
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* right (i.e. discard least significant bits) to fit into
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* the appropriate field in the instruction word.
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* - flags indicating whether
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* * the relocation involves a symbol
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* * the relocation is relative to the current position
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* * the relocation is for a GOT entry
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* * the relocation is relative to the load address
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*
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*/
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#define _RF_S 0x80000000 /* Resolve symbol */
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#define _RF_A 0x40000000 /* Use addend */
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#define _RF_P 0x20000000 /* Location relative */
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#define _RF_G 0x10000000 /* GOT offset */
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#define _RF_B 0x08000000 /* Load address relative */
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#define _RF_U 0x04000000 /* Unaligned */
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#define _RF_SZ(s) (((s) & 0xff) << 8) /* memory target size */
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#define _RF_RS(s) ( (s) & 0xff) /* right shift */
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static const int reloc_target_flags[] = {
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0, /* NONE */
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_RF_S|_RF_A| _RF_SZ(8) | _RF_RS(0), /* RELOC_8 */
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_RF_S|_RF_A| _RF_SZ(16) | _RF_RS(0), /* RELOC_16 */
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_RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* RELOC_32 */
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_RF_S|_RF_A|_RF_P| _RF_SZ(8) | _RF_RS(0), /* DISP_8 */
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_RF_S|_RF_A|_RF_P| _RF_SZ(16) | _RF_RS(0), /* DISP_16 */
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_RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* DISP_32 */
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_RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WDISP_30 */
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_RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WDISP_22 */
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_RF_S|_RF_A| _RF_SZ(32) | _RF_RS(10), /* HI22 */
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_RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 22 */
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_RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 13 */
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_RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* LO10 */
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_RF_G| _RF_SZ(32) | _RF_RS(0), /* GOT10 */
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_RF_G| _RF_SZ(32) | _RF_RS(0), /* GOT13 */
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_RF_G| _RF_SZ(32) | _RF_RS(10), /* GOT22 */
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_RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* PC10 */
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_RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(10), /* PC22 */
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_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WPLT30 */
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_RF_SZ(32) | _RF_RS(0), /* COPY */
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_RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* GLOB_DAT */
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_RF_SZ(32) | _RF_RS(0), /* JMP_SLOT */
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_RF_A| _RF_B| _RF_SZ(32) | _RF_RS(0), /* RELATIVE */
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_RF_S|_RF_A| _RF_U| _RF_SZ(32) | _RF_RS(0), /* UA_32 */
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};
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#ifdef RTLD_DEBUG_RELOC
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static const char *reloc_names[] = {
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"NONE", "RELOC_8", "RELOC_16", "RELOC_32", "DISP_8",
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"DISP_16", "DISP_32", "WDISP_30", "WDISP_22", "HI22",
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"22", "13", "LO10", "GOT10", "GOT13",
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"GOT22", "PC10", "PC22", "WPLT30", "COPY",
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"GLOB_DAT", "JMP_SLOT", "RELATIVE", "UA_32"
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};
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#endif
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#define RELOC_RESOLVE_SYMBOL(t) ((reloc_target_flags[t] & _RF_S) != 0)
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#define RELOC_PC_RELATIVE(t) ((reloc_target_flags[t] & _RF_P) != 0)
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#define RELOC_BASE_RELATIVE(t) ((reloc_target_flags[t] & _RF_B) != 0)
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#define RELOC_UNALIGNED(t) ((reloc_target_flags[t] & _RF_U) != 0)
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#define RELOC_USE_ADDEND(t) ((reloc_target_flags[t] & _RF_A) != 0)
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#define RELOC_TARGET_SIZE(t) ((reloc_target_flags[t] >> 8) & 0xff)
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#define RELOC_VALUE_RIGHTSHIFT(t) (reloc_target_flags[t] & 0xff)
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static const int reloc_target_bitmask[] = {
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#define _BM(x) (~(-(1ULL << (x))))
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0, /* NONE */
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_BM(8), _BM(16), _BM(32), /* RELOC_8, _16, _32 */
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_BM(8), _BM(16), _BM(32), /* DISP8, DISP16, DISP32 */
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_BM(30), _BM(22), /* WDISP30, WDISP22 */
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_BM(22), _BM(22), /* HI22, _22 */
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_BM(13), _BM(10), /* RELOC_13, _LO10 */
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_BM(10), _BM(13), _BM(22), /* GOT10, GOT13, GOT22 */
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_BM(10), _BM(22), /* _PC10, _PC22 */
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_BM(30), 0, /* _WPLT30, _COPY */
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-1, -1, -1, /* _GLOB_DAT, JMP_SLOT, _RELATIVE */
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_BM(32) /* _UA32 */
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#undef _BM
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};
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#define RELOC_VALUE_BITMASK(t) (reloc_target_bitmask[t])
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void _rtld_bind_start(void);
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void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
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caddr_t _rtld_bind(const Obj_Entry *, Elf_Word);
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static inline int _rtld_relocate_plt_object(const Obj_Entry *,
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const Elf_Rela *, Elf_Addr *);
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void
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_rtld_setup_pltgot(const Obj_Entry *obj)
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{
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/*
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* PLTGOT is the PLT on the sparc.
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* The first entry holds the call the dynamic linker.
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* We construct a `call' sequence that transfers
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* to `_rtld_bind_start()'.
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* The second entry holds the object identification.
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* Note: each PLT entry is three words long.
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*/
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#define SAVE 0x9de3bfa0 /* i.e. `save %sp,-96,%sp' */
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#define CALL 0x40000000
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#define NOP 0x01000000
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obj->pltgot[0] = SAVE;
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obj->pltgot[1] = CALL |
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((Elf_Addr) &_rtld_bind_start - (Elf_Addr) &obj->pltgot[1]) >> 2;
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obj->pltgot[2] = NOP;
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obj->pltgot[3] = (Elf_Addr) obj;
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}
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void
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_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
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{
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const Elf_Rela *rela = 0, *relalim;
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Elf_Addr relasz = 0;
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Elf_Addr *where;
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for (; dynp->d_tag != DT_NULL; dynp++) {
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switch (dynp->d_tag) {
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case DT_RELA:
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rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr);
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break;
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case DT_RELASZ:
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relasz = dynp->d_un.d_val;
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break;
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}
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}
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relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz);
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for (; rela < relalim; rela++) {
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where = (Elf_Addr *)(relocbase + rela->r_offset);
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*where += (Elf_Addr)(relocbase + rela->r_addend);
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}
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}
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int
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_rtld_relocate_nonplt_objects(Obj_Entry *obj)
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{
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const Elf_Rela *rela;
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for (rela = obj->rela; rela < obj->relalim; rela++) {
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Elf_Addr *where;
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Elf_Word type, value, mask;
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const Elf_Sym *def = NULL;
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const Obj_Entry *defobj = NULL;
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unsigned long symnum;
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where = (Elf_Addr *) (obj->relocbase + rela->r_offset);
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symnum = ELF_R_SYM(rela->r_info);
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type = ELF_R_TYPE(rela->r_info);
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if (type == R_TYPE(NONE))
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continue;
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/* We do JMP_SLOTs in _rtld_bind() below */
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if (type == R_TYPE(JMP_SLOT))
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continue;
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/* COPY relocs are also handled elsewhere */
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if (type == R_TYPE(COPY))
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continue;
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/*
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* We use the fact that relocation types are an `enum'
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* Note: R_SPARC_6 is currently numerically largest.
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*/
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if (type > R_TYPE(6))
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return (-1);
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value = rela->r_addend;
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/*
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* Handle relative relocs here, as an optimization.
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*/
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if (type == R_TYPE(RELATIVE)) {
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*where += (Elf_Addr)(obj->relocbase + value);
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rdbg(("RELATIVE in %s --> %p", obj->path,
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(void *)*where));
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continue;
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}
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if (RELOC_RESOLVE_SYMBOL(type)) {
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/* Find the symbol */
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def = _rtld_find_symdef(symnum, obj, &defobj, false);
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if (def == NULL)
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return (-1);
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/* Add in the symbol's absolute address */
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value += (Elf_Word)(defobj->relocbase + def->st_value);
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}
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if (RELOC_PC_RELATIVE(type)) {
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value -= (Elf_Word)where;
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}
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if (RELOC_BASE_RELATIVE(type)) {
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/*
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* Note that even though sparcs use `Elf_rela'
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* exclusively we still need the implicit memory addend
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* in relocations referring to GOT entries.
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* Undoubtedly, someone f*cked this up in the distant
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* past, and now we're stuck with it in the name of
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* compatibility for all eternity..
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*
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* In any case, the implicit and explicit should be
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* mutually exclusive. We provide a check for that
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* here.
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*/
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#define DIAGNOSTIC
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#ifdef DIAGNOSTIC
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if (value != 0 && *where != 0) {
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xprintf("BASE_REL(%s): where=%p, *where 0x%x, "
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"addend=0x%x, base %p\n",
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obj->path, where, *where,
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rela->r_addend, obj->relocbase);
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}
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#endif
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value += (Elf_Word)(obj->relocbase + *where);
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}
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mask = RELOC_VALUE_BITMASK(type);
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value >>= RELOC_VALUE_RIGHTSHIFT(type);
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value &= mask;
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if (RELOC_UNALIGNED(type)) {
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/* Handle unaligned relocations. */
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Elf_Addr tmp = 0;
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char *ptr = (char *)where;
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int i, size = RELOC_TARGET_SIZE(type)/8;
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/* Read it in one byte at a time. */
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for (i=0; i<size; i++)
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tmp = (tmp << 8) | ptr[i];
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tmp &= ~mask;
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tmp |= value;
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/* Write it back out. */
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for (i=0; i<size; i++)
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ptr[i] = ((tmp >> (8*i)) & 0xff);
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#ifdef RTLD_DEBUG_RELOC
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value = (Elf_Word)tmp;
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#endif
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} else {
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*where &= ~mask;
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*where |= value;
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#ifdef RTLD_DEBUG_RELOC
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value = (Elf_Word)*where;
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#endif
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}
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#ifdef RTLD_DEBUG_RELOC
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if (RELOC_RESOLVE_SYMBOL(type)) {
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rdbg(("%s %s in %s --> %p in %s", reloc_names[type],
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obj->strtab + obj->symtab[symnum].st_name,
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obj->path, (void *)value, defobj->path));
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} else {
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rdbg(("%s in %s --> %p", reloc_names[type],
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obj->path, (void *)value));
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}
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#endif
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}
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return (0);
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}
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int
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_rtld_relocate_plt_lazy(const Obj_Entry *obj)
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{
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return (0);
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}
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caddr_t
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_rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
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{
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const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff);
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Elf_Addr value;
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int err;
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value = 0; /* XXX gcc */
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|
|
||
|
|
err = _rtld_relocate_plt_object(obj, rela, &value);
|
||
|
|
if (err)
|
||
|
|
_rtld_die();
|
||
|
|
|
||
|
|
return (caddr_t)value;
|
||
|
|
}
|
||
|
|
|
||
|
|
int
|
||
|
|
_rtld_relocate_plt_objects(const Obj_Entry *obj)
|
||
|
|
{
|
||
|
|
const Elf_Rela *rela = obj->pltrela;
|
||
|
|
|
||
|
|
for (; rela < obj->pltrelalim; rela++)
|
||
|
|
if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
|
||
|
|
return -1;
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static inline int
|
||
|
|
_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp)
|
||
|
|
{
|
||
|
|
const Elf_Sym *def;
|
||
|
|
const Obj_Entry *defobj;
|
||
|
|
Elf_Word *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
|
||
|
|
Elf_Addr value;
|
||
|
|
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;
|
||
|
|
|
||
|
|
value = (Elf_Addr)(defobj->relocbase + def->st_value);
|
||
|
|
rdbg(("bind now/fixup in %s --> new=%p",
|
||
|
|
defobj->strtab + def->st_name, (void *)value));
|
||
|
|
|
||
|
|
/*
|
||
|
|
* At the PLT entry pointed at by `where', we now construct
|
||
|
|
* a direct transfer to the now fully resolved function
|
||
|
|
* address. The resulting code in the jump slot is:
|
||
|
|
*
|
||
|
|
* sethi %hi(roffset), %g1
|
||
|
|
* sethi %hi(addr), %g1
|
||
|
|
* jmp %g1+%lo(addr)
|
||
|
|
*
|
||
|
|
* We write the third instruction first, since that leaves the
|
||
|
|
* previous `b,a' at the second word in place. Hence the whole
|
||
|
|
* PLT slot can be atomically change to the new sequence by
|
||
|
|
* writing the `sethi' instruction at word 2.
|
||
|
|
*/
|
||
|
|
#define SETHI 0x03000000
|
||
|
|
#define JMP 0x81c06000
|
||
|
|
#define NOP 0x01000000
|
||
|
|
where[2] = JMP | (value & 0x000003ff);
|
||
|
|
where[1] = SETHI | ((value >> 10) & 0x003fffff);
|
||
|
|
__asm volatile("iflush %0+8" : : "r" (where));
|
||
|
|
__asm volatile("iflush %0+4" : : "r" (where));
|
||
|
|
|
||
|
|
if (tp)
|
||
|
|
*tp = value;
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|