531 lines
16 KiB
C
531 lines
16 KiB
C
/* Machine-dependent ELF dynamic relocation inline functions. x86-64 version.
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Copyright (C) 2001, 2002 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Andreas Jaeger <aj@suse.de>.
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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, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#ifndef dl_machine_h
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#define dl_machine_h
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#define ELF_MACHINE_NAME "x86_64"
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#include <sys/param.h>
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/* Return nonzero iff ELF header is compatible with the running host. */
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static inline int __attribute__ ((unused))
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elf_machine_matches_host (const Elf64_Ehdr *ehdr)
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{
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return ehdr->e_machine == EM_X86_64;
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}
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/* Return the link-time address of _DYNAMIC. Conveniently, this is the
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first element of the GOT. This must be inlined in a function which
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uses global data. */
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static inline Elf64_Addr __attribute__ ((unused))
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elf_machine_dynamic (void)
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{
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Elf64_Addr addr;
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/* This works because we have our GOT address available in the small PIC
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model. */
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addr = (Elf64_Addr) &_DYNAMIC;
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return addr;
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}
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/* Return the run-time load address of the shared object. */
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static inline Elf64_Addr __attribute__ ((unused))
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elf_machine_load_address (void)
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{
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register Elf64_Addr addr, tmp;
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/* The easy way is just the same as on x86:
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leaq _dl_start, %0
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leaq _dl_start(%%rip), %1
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subq %0, %1
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but this does not work with binutils since we then have
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a R_X86_64_32S relocation in a shared lib.
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Instead we store the address of _dl_start in the data section
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and compare it with the current value that we can get via
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an RIP relative addressing mode. */
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asm ("movq 1f(%%rip), %1\n"
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"0:\tleaq _dl_start(%%rip), %0\n\t"
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"subq %1, %0\n\t"
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".section\t.data\n"
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"1:\t.quad _dl_start\n\t"
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".previous\n\t"
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: "=r" (addr), "=r" (tmp) : : "cc");
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return 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 __attribute__ ((unused))
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elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
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{
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Elf64_Addr *got;
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extern void _dl_runtime_resolve (Elf64_Word) attribute_hidden;
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extern void _dl_runtime_profile (Elf64_Word) attribute_hidden;
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if (l->l_info[DT_JMPREL] && lazy)
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{
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/* The GOT entries for functions in the PLT have not yet been filled
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in. Their initial contents will arrange when called to push an
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offset into the .rel.plt section, push _GLOBAL_OFFSET_TABLE_[1],
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and then jump to _GLOBAL_OFFSET_TABLE[2]. */
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got = (Elf64_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
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/* If a library is prelinked but we have to relocate anyway,
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we have to be able to undo the prelinking of .got.plt.
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The prelinker saved us here address of .plt + 0x16. */
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if (got[1])
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{
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l->l_mach.plt = got[1] + l->l_addr;
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l->l_mach.gotplt = (Elf64_Addr) &got[3];
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}
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got[1] = (Elf64_Addr) l; /* Identify this shared object. */
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/* The got[2] entry contains the address of a function which gets
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called to get the address of a so far unresolved function and
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jump to it. The profiling extension of the dynamic linker allows
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to intercept the calls to collect information. In this case we
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don't store the address in the GOT so that all future calls also
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end in this function. */
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if (__builtin_expect (profile, 0))
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{
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got[2] = (Elf64_Addr) &_dl_runtime_profile;
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if (_dl_name_match_p (GL(dl_profile), l))
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/* This is the object we are looking for. Say that we really
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want profiling and the timers are started. */
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GL(dl_profile_map) = l;
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}
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else
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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] = (Elf64_Addr) &_dl_runtime_resolve;
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}
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return lazy;
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}
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/* This code is used in dl-runtime.c to call the `fixup' function
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and then redirect to the address it returns. */
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#ifndef PROF
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# define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\n\
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.text\n\
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.globl _dl_runtime_resolve\n\
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.type _dl_runtime_resolve, @function\n\
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.align 16\n\
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_dl_runtime_resolve:\n\
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pushq %rax # Preserve registers otherwise clobbered.\n\
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pushq %rcx\n\
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pushq %rdx\n\
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pushq %rsi\n\
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pushq %rdi\n\
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pushq %r8\n\
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pushq %r9\n\
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movq 64(%rsp), %rsi # Copy args pushed by PLT in register.\n\
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movq %rsi,%r11 # Multiply by 24\n\
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addq %r11,%rsi\n\
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addq %r11,%rsi\n\
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shlq $3, %rsi\n\
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movq 56(%rsp), %rdi # %rdi: link_map, %rsi: reloc_offset\n\
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call fixup # Call resolver.\n\
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movq %rax, %r11 # Save return value\n\
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popq %r9 # Get register content back.\n\
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popq %r8\n\
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popq %rdi\n\
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popq %rsi\n\
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popq %rdx\n\
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popq %rcx\n\
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popq %rax\n\
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addq $16,%rsp # Adjust stack\n\
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jmp *%r11 # Jump to function address.\n\
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.size _dl_runtime_resolve, .-_dl_runtime_resolve\n\
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\n\
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.globl _dl_runtime_profile\n\
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.type _dl_runtime_profile, @function\n\
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.align 16\n\
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_dl_runtime_profile:\n\
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pushq %rax # Preserve registers otherwise clobbered.\n\
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pushq %rcx\n\
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pushq %rdx\n\
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pushq %rsi\n\
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pushq %rdi\n\
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pushq %r8\n\
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pushq %r9\n\
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movq 72(%rsp), %rdx # Load return address if needed\n\
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movq 64(%rsp), %rsi # Copy args pushed by PLT in register.\n\
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movq %rsi,%r11 # Multiply by 24\n\
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addq %r11,%rsi\n\
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addq %r11,%rsi\n\
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shlq $3, %rsi\n\
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movq 56(%rsp), %rdi # %rdi: link_map, %rsi: reloc_offset\n\
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call profile_fixup # Call resolver.\n\
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movq %rax, %r11 # Save return value\n\
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popq %r9 # Get register content back.\n\
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popq %r8\n\
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popq %rdi\n\
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popq %rsi\n\
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popq %rdx\n\
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popq %rcx\n\
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popq %rax\n\
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addq $16,%rsp # Adjust stack\n\
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jmp *%r11 # Jump to function address.\n\
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.size _dl_runtime_profile, .-_dl_runtime_profile\n\
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.previous\n\
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");
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#else
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# define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\n\
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.text\n\
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.globl _dl_runtime_resolve\n\
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.globl _dl_runtime_profile\n\
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.type _dl_runtime_resolve, @function\n\
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.type _dl_runtime_profile, @function\n\
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.align 16\n\
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_dl_runtime_resolve:\n\
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_dl_runtime_profile:\n\
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pushq %rax # Preserve registers otherwise clobbered.\n\
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pushq %rcx\n\
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pushq %rdx\n\
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pushq %rsi\n\
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pushq %rdi\n\
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pushq %r8\n\
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pushq %r9\n\
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movq 64(%rsp), %rsi # Copy args pushed by PLT in register.\n\
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movq %rsi,%r11 # Multiply by 24\n\
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addq %r11,%rsi\n\
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addq %r11,%rsi\n\
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shlq $3, %rsi\n\
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movq 56(%rsp), %rdi # %rdi: link_map, %rsi: reloc_offset\n\
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call fixup # Call resolver.\n\
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movq %rax, %r11 # Save return value\n\
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popq %r9 # Get register content back.\n\
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popq %r8\n\
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popq %rdi\n\
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popq %rsi\n\
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popq %rdx\n\
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popq %rcx\n\
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popq %rax\n\
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addq $16,%rsp # Adjust stack\n\
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jmp *%r11 # Jump to function address.\n\
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.size _dl_runtime_resolve, .-_dl_runtime_resolve\n\
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.size _dl_runtime_profile, .-_dl_runtime_profile\n\
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.previous\n\
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");
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#endif
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/* Initial entry point code for the dynamic linker.
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The C function `_dl_start' is the real entry point;
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its return value is the user program's entry point. */
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#define RTLD_START asm ("\n\
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.text\n\
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.align 16\n\
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.globl _start\n\
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.globl _dl_start_user\n\
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_start:\n\
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movq %rsp, %rdi\n\
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call _dl_start\n\
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_dl_start_user:\n\
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# Save the user entry point address in %r12.\n\
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movq %rax, %r12\n\
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# Store the highest stack address\n\
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movq __libc_stack_end@GOTPCREL(%rip), %rax\n\
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movq %rsp, (%rax)\n\
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# See if we were run as a command with the executable file\n\
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# name as an extra leading argument.\n\
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movq _dl_skip_args@GOTPCREL(%rip), %rax\n\
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movl (%rax), %eax\n\
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# Pop the original argument count.\n\
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popq %rdx\n\
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# Adjust the stack pointer to skip _dl_skip_args words.\n\
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leaq (%rsp,%rax,8), %rsp\n\
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# Subtract _dl_skip_args from argc.\n\
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subl %eax, %edx\n\
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# Push argc back on the stack.\n\
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pushq %rdx\n\
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# Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
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# argc -> rsi\n\
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movq %rdx, %rsi\n\
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# _dl_loaded -> rdi\n\
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movq _rtld_local@GOTPCREL(%rip), %rdi\n\
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movq (%rdi), %rdi\n\
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# env -> rcx\n\
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leaq 16(%rsp,%rdx,8), %rcx\n\
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# argv -> rdx\n\
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leaq 8(%rsp), %rdx\n\
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# Call the function to run the initializers.\n\
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call _dl_init_internal@PLT\n\
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# Pass our finalizer function to the user in %rdx, as per ELF ABI.\n\
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movq _dl_fini@GOTPCREL(%rip), %rdx\n\
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# Jump to the user's entry point.\n\
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jmp *%r12\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 or
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TLS variable, so undefined references should not be allowed to
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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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#ifdef USE_TLS
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# define elf_machine_type_class(type) \
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((((type) == R_X86_64_JUMP_SLOT \
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|| (type) == R_X86_64_DTPMOD64 \
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|| (type) == R_X86_64_DTPOFF64 || (type) == R_X86_64_TPOFF64) \
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* ELF_RTYPE_CLASS_PLT) \
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| (((type) == R_X86_64_COPY) * ELF_RTYPE_CLASS_COPY))
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#else
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# define elf_machine_type_class(type) \
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((((type) == R_X86_64_JUMP_SLOT) * ELF_RTYPE_CLASS_PLT) \
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| (((type) == R_X86_64_COPY) * ELF_RTYPE_CLASS_COPY))
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#endif
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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_X86_64_JUMP_SLOT
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/* The x86-64 never uses Elf64_Rel relocations. */
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#define ELF_MACHINE_NO_REL 1
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/* We define an initialization functions. This is called very early in
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_dl_sysdep_start. */
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#define DL_PLATFORM_INIT dl_platform_init ()
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static inline void __attribute__ ((unused))
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dl_platform_init (void)
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{
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if (GL(dl_platform) != NULL && *GL(dl_platform) == '\0')
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/* Avoid an empty string which would disturb us. */
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GL(dl_platform) = NULL;
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}
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static inline Elf64_Addr
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elf_machine_fixup_plt (struct link_map *map, lookup_t t,
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const Elf64_Rela *reloc,
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Elf64_Addr *reloc_addr, Elf64_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. On x86-64 the
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JUMP_SLOT relocation ignores the addend. */
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static inline Elf64_Addr
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elf_machine_plt_value (struct link_map *map, const Elf64_Rela *reloc,
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Elf64_Addr value)
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{
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return value;
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}
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#endif /* !dl_machine_h */
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#ifdef RESOLVE
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/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
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MAP is the object containing the reloc. */
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static inline void
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elf_machine_rela (struct link_map *map, const Elf64_Rela *reloc,
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const Elf64_Sym *sym, const struct r_found_version *version,
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Elf64_Addr *const reloc_addr)
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{
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const unsigned long int r_type = ELF64_R_TYPE (reloc->r_info);
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#if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC
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if (__builtin_expect (r_type == R_X86_64_RELATIVE, 0))
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{
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# if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
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/* This is defined in rtld.c, but nowhere in the static libc.a;
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make the reference weak so static programs can still link.
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This declaration cannot be done when compiling rtld.c
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(i.e. #ifdef RTLD_BOOTSTRAP) because rtld.c contains the
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common defn for _dl_rtld_map, which is incompatible with a
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weak decl in the same file. */
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# ifndef SHARED
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weak_extern (GL(dl_rtld_map));
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# endif
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if (map != &GL(dl_rtld_map)) /* Already done in rtld itself. */
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# endif
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*reloc_addr = map->l_addr + reloc->r_addend;
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}
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else
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#endif
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if (__builtin_expect (r_type == R_X86_64_NONE, 0))
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return;
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else
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{
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#ifndef RTLD_BOOTSTRAP
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const Elf64_Sym *const refsym = sym;
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#endif
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#if defined USE_TLS && !defined RTLD_BOOTSTRAP
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struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
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Elf64_Addr value = sym == NULL ? 0 : sym_map->l_addr + sym->st_value;
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#else
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Elf64_Addr value = RESOLVE (&sym, version, r_type);
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# ifndef RTLD_BOOTSTRAP
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if (sym != NULL)
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# endif
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value += sym->st_value;
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#endif
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#if defined RTLD_BOOTSTRAP && !(USE_TLS && HAVE___THREAD)
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assert (r_type == R_X86_64_GLOB_DAT || r_type == R_X86_64_JUMP_SLOT);
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*reloc_addr = value + reloc->r_addend;
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#else
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switch (r_type)
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{
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case R_X86_64_GLOB_DAT:
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case R_X86_64_JUMP_SLOT:
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*reloc_addr = value + reloc->r_addend;
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break;
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|
#ifdef USE_TLS
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case R_X86_64_DTPMOD64:
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|
# ifdef RTLD_BOOTSTRAP
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/* During startup the dynamic linker is always the module
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|
with index 1.
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XXX If this relocation is necessary move before RESOLVE
|
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call. */
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*reloc_addr = 1;
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# else
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|
/* Get the information from the link map returned by the
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resolve function. */
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if (sym_map != NULL)
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*reloc_addr = sym_map->l_tls_modid;
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# endif
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break;
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case R_X86_64_DTPOFF64:
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# ifndef RTLD_BOOTSTRAP
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/* During relocation all TLS symbols are defined and used.
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Therefore the offset is already correct. */
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if (sym != NULL)
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*reloc_addr = sym->st_value + reloc->r_addend;
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# endif
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break;
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case R_X86_64_TPOFF64:
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/* The offset is negative, forward from the thread pointer. */
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# ifndef RTLD_BOOTSTRAP
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if (sym != NULL)
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# endif
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|
/* We know the offset of the object the symbol is contained in.
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|
It is a negative value which will be added to the
|
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thread pointer. */
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*reloc_addr = (sym->st_value + reloc->r_addend
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|
- sym_map->l_tls_offset);
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break;
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#endif /* use TLS */
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|
|
#ifndef RTLD_BOOTSTRAP
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|
case R_X86_64_64:
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|
*reloc_addr = value + reloc->r_addend;
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break;
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|
case R_X86_64_32:
|
|
*(unsigned int *) reloc_addr = value + reloc->r_addend;
|
|
if (value + reloc->r_addend > UINT_MAX)
|
|
{
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|
const char *strtab;
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|
strtab = (const char *) D_PTR (map, l_info[DT_STRTAB]);
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|
|
|
_dl_error_printf ("\
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|
%s: Symbol `%s' causes overflow in R_X86_64_32 relocation\n",
|
|
rtld_progname ?: "<program name unknown>",
|
|
strtab + refsym->st_name);
|
|
}
|
|
break;
|
|
case R_X86_64_PC32:
|
|
*(unsigned int *) reloc_addr = value + reloc->r_addend
|
|
- (Elf64_Addr) reloc_addr;
|
|
if (value + reloc->r_addend - (Elf64_Addr) reloc_addr
|
|
!= (unsigned int)(value + reloc->r_addend - (Elf64_Addr) reloc_addr))
|
|
{
|
|
const char *strtab;
|
|
|
|
strtab = (const char *) D_PTR (map, l_info[DT_STRTAB]);
|
|
|
|
_dl_error_printf ("\
|
|
%s: Symbol `%s' causes overflow in R_X86_64_PC32 relocation\n",
|
|
rtld_progname ?: "<program name unknown>",
|
|
strtab + refsym->st_name);
|
|
}
|
|
break;
|
|
case R_X86_64_COPY:
|
|
if (sym == NULL)
|
|
/* This can happen in trace mode if an object could not be
|
|
found. */
|
|
break;
|
|
if (__builtin_expect (sym->st_size > refsym->st_size, 0)
|
|
|| (__builtin_expect (sym->st_size < refsym->st_size, 0)
|
|
&& GL(dl_verbose)))
|
|
{
|
|
const char *strtab;
|
|
|
|
strtab = (const char *) D_PTR (map, l_info[DT_STRTAB]);
|
|
_dl_error_printf ("\
|
|
%s: Symbol `%s' has different size in shared object, consider re-linking\n",
|
|
rtld_progname ?: "<program name unknown>",
|
|
strtab + refsym->st_name);
|
|
}
|
|
memcpy (reloc_addr, (void *) value, MIN (sym->st_size,
|
|
refsym->st_size));
|
|
break;
|
|
default:
|
|
_dl_reloc_bad_type (map, r_type, 0);
|
|
break;
|
|
#endif
|
|
}
|
|
#endif
|
|
}
|
|
}
|
|
|
|
static inline void
|
|
elf_machine_rela_relative (Elf64_Addr l_addr, const Elf64_Rela *reloc,
|
|
Elf64_Addr *const reloc_addr)
|
|
{
|
|
assert (ELF64_R_TYPE (reloc->r_info) == R_X86_64_RELATIVE);
|
|
*reloc_addr = l_addr + reloc->r_addend;
|
|
}
|
|
|
|
static inline void
|
|
elf_machine_lazy_rel (struct link_map *map,
|
|
Elf64_Addr l_addr, const Elf64_Rela *reloc)
|
|
{
|
|
Elf64_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
|
|
const unsigned long int r_type = ELF64_R_TYPE (reloc->r_info);
|
|
|
|
/* Check for unexpected PLT reloc type. */
|
|
if (__builtin_expect (r_type == R_X86_64_JUMP_SLOT, 1))
|
|
{
|
|
if (__builtin_expect (map->l_mach.plt, 0) == 0)
|
|
*reloc_addr += l_addr;
|
|
else
|
|
*reloc_addr =
|
|
map->l_mach.plt
|
|
+ (((Elf64_Addr) reloc_addr) - map->l_mach.gotplt) * 2;
|
|
}
|
|
else
|
|
_dl_reloc_bad_type (map, r_type, 1);
|
|
}
|
|
|
|
#endif /* RESOLVE */
|