36f451a6d9
* LP32 should use sa_restorer too. gdb expects this, and future (>= 3.15) x86 kernels will apparently stop supporting the case where SA_RESTORER isn't set. * gdb and libunwind care about the exact instruction sequences, so we need to modify the code slightly in a few cases to match what they're looking for. * gdb also cares about the exact function names (for some architectures), so we need to use __restore and __restore_rt rather than __sigreturn and __rt_sigreturn. * It's possible that we don't have a VDSO; dl_iterate_phdr shouldn't assume that getauxval(AT_SYSINFO_EHDR) will return a non-null pointer. This fixes unwinding through a signal handler in gdb for all architectures. It doesn't fix libunwind for arm and arm64. I'll keep investigating that... Bug: 17436734 Change-Id: Ic1ea1184db6655c5d96180dc07bcc09628e647cb
86 lines
3.3 KiB
C++
86 lines
3.3 KiB
C++
/*
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* Copyright (C) 2006 The Android Open Source Project
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* All rights reserved.
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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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* * 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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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <elf.h>
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#include <string.h>
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#include <sys/auxv.h>
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#include <sys/types.h>
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#include <link.h>
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/* ld provides this to us in the default link script */
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extern "C" void* __executable_start;
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int dl_iterate_phdr(int (*cb)(struct dl_phdr_info* info, size_t size, void* data), void* data) {
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ElfW(Ehdr)* ehdr = reinterpret_cast<ElfW(Ehdr)*>(&__executable_start);
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if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) {
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return -1;
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}
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// Dynamic binaries get their dl_iterate_phdr from the dynamic linker, but
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// static binaries get this. We don't have a list of shared objects to
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// iterate over, since there's really only a single monolithic blob of
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// code/data, plus optionally a VDSO.
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struct dl_phdr_info exe_info;
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exe_info.dlpi_addr = 0;
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exe_info.dlpi_name = NULL;
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exe_info.dlpi_phdr = reinterpret_cast<ElfW(Phdr)*>(reinterpret_cast<uintptr_t>(ehdr) + ehdr->e_phoff);
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exe_info.dlpi_phnum = ehdr->e_phnum;
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#if defined(AT_SYSINFO_EHDR)
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// Try the executable first.
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int rc = cb(&exe_info, sizeof(exe_info), data);
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if (rc != 0) {
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return rc;
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}
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// Try the VDSO if that didn't work.
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ElfW(Ehdr)* ehdr_vdso = reinterpret_cast<ElfW(Ehdr)*>(getauxval(AT_SYSINFO_EHDR));
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if (ehdr_vdso == nullptr) {
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// There is no VDSO, so there's nowhere left to look.
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return rc;
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}
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struct dl_phdr_info vdso_info;
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vdso_info.dlpi_addr = 0;
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vdso_info.dlpi_name = NULL;
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vdso_info.dlpi_phdr = reinterpret_cast<ElfW(Phdr)*>(reinterpret_cast<char*>(ehdr_vdso) + ehdr_vdso->e_phoff);
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vdso_info.dlpi_phnum = ehdr_vdso->e_phnum;
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for (size_t i = 0; i < vdso_info.dlpi_phnum; ++i) {
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if (vdso_info.dlpi_phdr[i].p_type == PT_LOAD) {
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vdso_info.dlpi_addr = (ElfW(Addr)) ehdr_vdso - vdso_info.dlpi_phdr[i].p_vaddr;
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break;
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}
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}
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return cb(&vdso_info, sizeof(vdso_info), data);
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#else
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// There's only the executable to try.
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return cb(&exe_info, sizeof(exe_info), data);
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#endif
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}
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