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This patch adds support for the ELFv2 ABI feature to remove function descriptors. See this GCC patch for in-depth discussion: http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01141.html This mostly involves two types of changes: updating assembler source files to the new logic, and updating the dynamic loader. After the refactoring in the previous patch, most of the assembler source changes can be handled simply by providing ELFv2 versions of the macros in sysdep.h. One somewhat non-obvious change is in __GI__setjmp: this used to "fall through" to the immediately following __setjmp ENTRY point. This is no longer safe in the ELFv2 since ENTRY defines both a global and a local entry point, and you cannot simply fall through to a global entry point as it requires r12 to be set up. Also, makecontext needs to be updated to set up registers according to the new ABI for calling into the context's start routine. The dynamic linker changes mostly consist of removing special code to handle function descriptors. We also need to support the new PLT and glink format used by the the ELFv2 linker, see: https://sourceware.org/ml/binutils/2013-10/msg00376.html In addition, the dynamic linker now verifies that the dynamic libraries it loads match its own ABI. The hack in VDSO_IFUNC_RET to "synthesize" a function descriptor for vDSO routines is also no longer necessary for ELFv2.
64 lines
1.9 KiB
C
64 lines
1.9 KiB
C
/* Machine-dependent ELF indirect relocation inline functions.
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PowerPC64 version.
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Copyright (C) 2009-2013 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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<http://www.gnu.org/licenses/>. */
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#ifndef _DL_IREL_H
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#define _DL_IREL_H
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#include <stdio.h>
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#include <unistd.h>
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#include <ldsodefs.h>
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#include <dl-machine.h>
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#define ELF_MACHINE_IRELA 1
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static inline Elf64_Addr
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__attribute ((always_inline))
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elf_ifunc_invoke (Elf64_Addr addr)
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{
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return ((Elf64_Addr (*) (unsigned long int)) (addr)) (GLRO(dl_hwcap));
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}
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static inline void
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__attribute ((always_inline))
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elf_irela (const Elf64_Rela *reloc)
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{
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unsigned int r_type = ELF64_R_TYPE (reloc->r_info);
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if (__builtin_expect (r_type == R_PPC64_IRELATIVE, 1))
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{
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Elf64_Addr *const reloc_addr = (void *) reloc->r_offset;
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Elf64_Addr value = elf_ifunc_invoke(reloc->r_addend);
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*reloc_addr = value;
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}
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else if (__builtin_expect (r_type == R_PPC64_JMP_IREL, 1))
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{
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Elf64_Addr *const reloc_addr = (void *) reloc->r_offset;
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Elf64_Addr value = elf_ifunc_invoke(reloc->r_addend);
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#if _CALL_ELF != 2
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*(Elf64_FuncDesc *) reloc_addr = *(Elf64_FuncDesc *) value;
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#else
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*reloc_addr = value;
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#endif
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}
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else
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__libc_fatal ("unexpected reloc type in static binary");
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}
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#endif /* dl-irel.h */
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