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342 lines
11 KiB
C
342 lines
11 KiB
C
/* Machine-dependent ELF dynamic relocation inline functions. ARC version.
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Copyright (C) 2020-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef dl_machine_h
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#define dl_machine_h
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#define ELF_MACHINE_NAME "arc"
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#include <entry.h>
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#ifndef ENTRY_POINT
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# error ENTRY_POINT needs to be defined for ARC
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#endif
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#include <string.h>
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#include <link.h>
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#include <dl-tls.h>
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/* Dynamic Linking ABI for ARCv2 ISA.
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PLT
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-------------------------------- <---- DT_PLTGOT
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| ld r11, [pcl, off-to-GOT[1] | 0
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| | 4
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plt0 | ld r10, [pcl, off-to-GOT[2] | 8
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| | 12
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| j [r10] | 16
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--------------------------------
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| Base address of GOT | 20
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--------------------------------
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| ld r12, [pcl, off-to-GOT[3] | 24
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plt1 | |
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| j.d [r12] | 32
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| mov r12, pcl | 36
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--------------------------------
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| | 40
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~ ~
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~ ~
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--------------------------------
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.got
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--------------
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| [0] |
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| ... | Runtime address for data symbols
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| [n] |
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--------------
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.got.plt
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--------------
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| [0] | Build address of .dynamic
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--------------
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| [1] | Module info - setup by ld.so
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--------------
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| [2] | resolver entry point
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--------------
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| [3] |
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| ... | Runtime address for function symbols
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| [f] |
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--------------
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For ARCompact, the PLT is 12 bytes due to short instructions
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--------------------------------
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| ld r12, [pcl, off-to-GOT[3] | 24 (12 bytes each)
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plt1 | |
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| j_s.d [r12] | 32
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| mov_s r12, pcl | 34
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--------------------------------
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| | 36 */
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/* Return nonzero iff ELF header is compatible with the running host. */
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static inline int
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elf_machine_matches_host (const ElfW(Ehdr) *ehdr)
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{
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return (ehdr->e_machine == EM_ARCV2 /* ARC HS. */
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|| ehdr->e_machine == EM_ARC_COMPACT); /* ARC 700. */
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}
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/* Get build time address of .dynamic as setup in GOT[0]
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This is called very early in _dl_start so it has not been relocated to
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runtime value. */
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static inline ElfW(Addr)
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elf_machine_dynamic (void)
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{
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extern const ElfW(Addr) _GLOBAL_OFFSET_TABLE_[] attribute_hidden;
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return _GLOBAL_OFFSET_TABLE_[0];
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}
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/* Return the run-time load address of the shared object. */
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static inline ElfW(Addr)
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elf_machine_load_address (void)
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{
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ElfW(Addr) build_addr, run_addr;
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/* For build address, below generates
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ld r0, [pcl, _GLOBAL_OFFSET_TABLE_@pcl]. */
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build_addr = elf_machine_dynamic ();
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__asm__ ("add %0, pcl, _DYNAMIC@pcl \n" : "=r" (run_addr));
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return run_addr - build_addr;
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}
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/* Set up the loaded object described by L so its unrelocated PLT
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entries will jump to the on-demand fixup code in dl-runtime.c. */
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static inline int
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__attribute__ ((always_inline))
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elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
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{
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extern void _dl_runtime_resolve (void);
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if (l->l_info[DT_JMPREL] && lazy)
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{
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/* On ARC DT_PLTGOT point to .plt whose 5th word (after the PLT header)
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contains the address of .got. */
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ElfW(Addr) *plt_base = (ElfW(Addr) *) D_PTR (l, l_info[DT_PLTGOT]);
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ElfW(Addr) *got = (ElfW(Addr) *) (plt_base[5] + l->l_addr);
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got[1] = (ElfW(Addr)) l; /* Identify this shared object. */
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/* This function will get called to fix up the GOT entry indicated by
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the offset on the stack, and then jump to the resolved address. */
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got[2] = (ElfW(Addr)) &_dl_runtime_resolve;
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}
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return lazy;
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}
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/* What this code does:
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-ldso starts execution here when kernel returns from execve
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-calls into generic ldso entry point _dl_start
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-optionally adjusts argc for executable if exec passed as cmd
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-calls into app main with address of finaliser. */
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#define RTLD_START asm ("\
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.text \n\
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.globl __start \n\
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.type __start, @function \n\
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__start: \n\
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/* (1). bootstrap ld.so. */ \n\
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bl.d _dl_start \n\
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mov_s r0, sp /* pass ptr to aux vector tbl. */ \n\
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mov r13, r0 /* safekeep app elf entry point. */ \n\
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\n\
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/* (2). If ldso ran with executable as arg. */ \n\
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/* skip the extra args calc by dl_start. */ \n\
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ld_s r1, [sp] /* orig argc. */ \n\
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ld r12, [pcl, _dl_skip_args@pcl] \n\
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breq r12, 0, 1f \n\
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\n\
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add2 sp, sp, r12 /* discard argv entries from stack. */ \n\
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sub_s r1, r1, r12 /* adjusted argc on stack. */ \n\
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st_s r1, [sp] \n\
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add r2, sp, 4 \n\
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/* intermediate LD for ST emcoding limitations. */ \n\
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ld r3, [pcl, _dl_argv@gotpc] \n\
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st r2, [r3] \n\
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1: \n\
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/* (3). call preinit stuff. */ \n\
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ld r0, [pcl, _rtld_local@pcl] \n\
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add r2, sp, 4 ; argv \n\
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add2 r3, r2, r1 \n\
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add r3, r3, 4 ; env \n\
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bl _dl_init@plt \n\
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\n\
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/* (4) call app elf entry point. */ \n\
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add r0, pcl, _dl_fini@pcl \n\
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j [r13] \n\
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\n\
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.size __start,.-__start \n\
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.previous \n\
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");
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/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
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PLT entries should not be allowed to define the value.
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ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
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of the main executable's symbols, as for a COPY reloc. */
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#define elf_machine_type_class(type) \
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((((type) == R_ARC_JUMP_SLOT \
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|| (type) == R_ARC_TLS_DTPMOD \
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|| (type) == R_ARC_TLS_DTPOFF \
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|| (type) == R_ARC_TLS_TPOFF) * ELF_RTYPE_CLASS_PLT) \
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| (((type) == R_ARC_COPY) * ELF_RTYPE_CLASS_COPY))
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/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
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#define ELF_MACHINE_JMP_SLOT R_ARC_JUMP_SLOT
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/* ARC uses Rela relocations. */
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#define ELF_MACHINE_NO_REL 1
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#define ELF_MACHINE_NO_RELA 0
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/* Fixup a PLT entry to bounce directly to the function at VALUE. */
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static inline ElfW(Addr)
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elf_machine_fixup_plt (struct link_map *map, lookup_t t,
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const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
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const ElfW(Rela) *reloc,
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ElfW(Addr) *reloc_addr, ElfW(Addr) value)
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{
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return *reloc_addr = value;
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}
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/* Return the final value of a plt relocation. */
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#define elf_machine_plt_value(map, reloc, value) (value)
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/* Names of the architecture-specific auditing callback functions. */
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#define ARCH_LA_PLTENTER arc_gnu_pltenter
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#define ARCH_LA_PLTEXIT arc_gnu_pltexit
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#endif /* dl_machine_h */
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#ifdef RESOLVE_MAP
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inline void
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__attribute__ ((always_inline))
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elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc,
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const ElfW(Sym) *sym, const struct r_found_version *version,
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void *const reloc_addr_arg, int skip_ifunc)
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{
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ElfW(Addr) r_info = reloc->r_info;
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const unsigned long int r_type = ELFW (R_TYPE) (r_info);
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ElfW(Addr) *const reloc_addr = reloc_addr_arg;
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if (__glibc_unlikely (r_type == R_ARC_RELATIVE))
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*reloc_addr += map->l_addr;
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else if (__glibc_unlikely (r_type == R_ARC_NONE))
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return;
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else
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{
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const ElfW(Sym) *const refsym = sym;
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struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
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ElfW(Addr) value = SYMBOL_ADDRESS (sym_map, sym, true);
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switch (r_type)
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{
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case R_ARC_COPY:
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if (__glibc_unlikely (sym == NULL))
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/* This can happen in trace mode if an object could not be
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found. */
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break;
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size_t size = sym->st_size;
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if (__glibc_unlikely (size != refsym->st_size))
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{
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const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
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if (sym->st_size > refsym->st_size)
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size = refsym->st_size;
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if (sym->st_size > refsym->st_size || GLRO(dl_verbose))
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_dl_error_printf ("\
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%s: Symbol `%s' has different size in shared object, consider re-linking\n",
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rtld_progname ?: "<program name unknown>",
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strtab + refsym->st_name);
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}
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memcpy (reloc_addr_arg, (void *) value, size);
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break;
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case R_ARC_GLOB_DAT:
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case R_ARC_JUMP_SLOT:
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*reloc_addr = value;
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break;
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case R_ARC_TLS_DTPMOD:
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if (sym_map != NULL)
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/* Get the information from the link map returned by the
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resolv function. */
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*reloc_addr = sym_map->l_tls_modid;
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break;
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case R_ARC_TLS_DTPOFF:
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if (sym != NULL)
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/* Offset set by the linker in the GOT entry would be overwritten
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by dynamic loader instead of added to the symbol location.
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Other target have the same approach on DTPOFF relocs. */
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*reloc_addr += sym->st_value;
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break;
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case R_ARC_TLS_TPOFF:
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if (sym != NULL)
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{
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CHECK_STATIC_TLS (map, sym_map);
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*reloc_addr = sym_map->l_tls_offset + sym->st_value + reloc->r_addend;
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}
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break;
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case R_ARC_32:
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*reloc_addr += value + reloc->r_addend;
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break;
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case R_ARC_PC32:
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*reloc_addr += value + reloc->r_addend - (unsigned long int) reloc_addr;
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break;
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default:
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_dl_reloc_bad_type (map, r_type, 0);
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break;
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}
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}
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}
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inline void
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__attribute__ ((always_inline))
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elf_machine_rela_relative (ElfW(Addr) l_addr, const ElfW(Rela) *reloc,
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void *const reloc_addr_arg)
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{
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ElfW(Addr) *const reloc_addr = reloc_addr_arg;
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*reloc_addr += l_addr;
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}
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inline void
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__attribute__ ((always_inline))
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elf_machine_lazy_rel (struct link_map *map, ElfW(Addr) l_addr,
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const ElfW(Rela) *reloc, int skip_ifunc)
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{
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ElfW(Addr) *const reloc_addr = (void *) (l_addr + reloc->r_offset);
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const unsigned int r_type = ELFW (R_TYPE) (reloc->r_info);
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if (r_type == R_ARC_JUMP_SLOT)
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*reloc_addr += l_addr;
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else
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_dl_reloc_bad_type (map, r_type, 1);
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}
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#endif /* RESOLVE_MAP */
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