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d4dfb6ff84
There is no requirement that all notes be placed in a single PT_NOTE. It looks like recent lld's actually put each section in its own PT_NOTE. This change looks for build-id in all PT_NOTE headers. Fixes #5525 Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com> Reviewed-by: Benny Halevy <bhalevy@scylladb.com> Message-Id: <20191227000311.421843-1-espindola@scylladb.com>
72 lines
1.7 KiB
C++
72 lines
1.7 KiB
C++
/*
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* Copyright (C) 2019 ScyllaDB
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*/
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#include "build_id.hh"
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#include <fmt/printf.h>
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#include <link.h>
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#include <seastar/core/align.hh>
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#include <sstream>
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using namespace seastar;
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static const Elf64_Nhdr* get_nt_build_id(dl_phdr_info* info) {
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auto base = info->dlpi_addr;
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const auto* h = info->dlpi_phdr;
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auto num_headers = info->dlpi_phnum;
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for (int i = 0; i != num_headers; ++i, ++h) {
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if (h->p_type != PT_NOTE) {
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continue;
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}
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auto* p = reinterpret_cast<const char*>(base) + h->p_vaddr;
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auto* e = p + h->p_memsz;
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while (p != e) {
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const auto* n = reinterpret_cast<const Elf64_Nhdr*>(p);
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if (n->n_type == NT_GNU_BUILD_ID) {
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return n;
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}
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p += sizeof(Elf64_Nhdr);
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p += n->n_namesz;
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p = align_up(p, 4);
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p += n->n_descsz;
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p = align_up(p, 4);
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}
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}
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assert(0 && "no NT_GNU_BUILD_ID note");
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}
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static int callback(dl_phdr_info* info, size_t size, void* data) {
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std::string& ret = *(std::string*)data;
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std::ostringstream os;
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// The first DSO is always the main program, which has an empty name.
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assert(strlen(info->dlpi_name) == 0);
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auto* n = get_nt_build_id(info);
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auto* p = reinterpret_cast<const char*>(n);
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p += sizeof(Elf64_Nhdr);
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p += n->n_namesz;
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p = align_up(p, 4);
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const char* desc = p;
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for (unsigned i = 0; i < n->n_descsz; ++i) {
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fmt::fprintf(os, "%02x", (unsigned char)*(desc + i));
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}
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ret = os.str();
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return 1;
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}
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std::string get_build_id() {
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std::string ret;
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int r = dl_iterate_phdr(callback, &ret);
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assert(r == 1);
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return ret;
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}
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