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Kernel: Work using copies of specific region data during a coredump
This limits our interaction with the "real" region tree (and therefore its lock) to the time where we actually read from the user address space.
This commit is contained in:
Tim Schumacher
Andreas Kling
parent
066c5acee1
commit
32a03cffeb
Notes:
sideshowbarker
2024-07-17 07:36:02 +09:00
Author: https://github.com/timschumi Commit: https://github.com/SerenityOS/serenity/commit/32a03cffeb Pull-request: https://github.com/SerenityOS/serenity/pull/14993 Reviewed-by: https://github.com/bgianfo
2 changed files with 148 additions and 75 deletions
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@ -25,9 +25,23 @@
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namespace Kernel {
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[[maybe_unused]] static bool looks_like_userspace_heap_region(Memory::Region const& region)
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bool Coredump::FlatRegionData::looks_like_userspace_heap_region() const
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{
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return region.name().starts_with("LibJS:"sv) || region.name().starts_with("malloc:"sv);
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return name().starts_with("LibJS:"sv) || name().starts_with("malloc:"sv);
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}
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bool Coredump::FlatRegionData::is_consistent_with_region(Memory::Region const& region) const
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{
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if (m_access != region.access())
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return false;
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if (m_page_count != region.page_count() || m_size != region.size())
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return false;
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if (m_vaddr != region.vaddr())
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return false;
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return true;
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}
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ErrorOr<NonnullOwnPtr<Coredump>> Coredump::try_create(NonnullLockRefPtr<Process> process, StringView output_path)
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@ -37,27 +51,37 @@ ErrorOr<NonnullOwnPtr<Coredump>> Coredump::try_create(NonnullLockRefPtr<Process>
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return EPERM;
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}
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Vector<FlatRegionData> regions;
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size_t number_of_regions = process->address_space().with([](auto& space) {
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return space->region_tree().regions().size();
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});
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TRY(regions.try_ensure_capacity(number_of_regions));
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TRY(process->address_space().with([&](auto& space) -> ErrorOr<void> {
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for (auto& region : space->region_tree().regions())
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TRY(regions.try_empend(region, TRY(KString::try_create(region.name()))));
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return {};
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}));
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auto description = TRY(try_create_target_file(process, output_path));
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return adopt_nonnull_own_or_enomem(new (nothrow) Coredump(move(process), move(description)));
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return adopt_nonnull_own_or_enomem(new (nothrow) Coredump(move(process), move(description), move(regions)));
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}
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Coredump::Coredump(NonnullLockRefPtr<Process> process, NonnullLockRefPtr<OpenFileDescription> description)
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Coredump::Coredump(NonnullLockRefPtr<Process> process, NonnullLockRefPtr<OpenFileDescription> description, Vector<FlatRegionData> regions)
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: m_process(move(process))
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, m_description(move(description))
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, m_regions(move(regions))
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{
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m_num_program_headers = 0;
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m_process->address_space().with([&](auto& space) {
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for (auto& region : space->region_tree().regions()) {
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for (auto& region : m_regions) {
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#if !INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS
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if (looks_like_userspace_heap_region(region))
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continue;
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if (region.looks_like_userspace_heap_region())
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continue;
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#endif
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if (region.access() == Memory::Region::Access::None)
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continue;
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++m_num_program_headers;
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}
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});
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if (region.access() == Memory::Region::Access::None)
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continue;
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++m_num_program_headers;
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}
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++m_num_program_headers; // +1 for NOTE segment
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}
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@ -135,39 +159,36 @@ ErrorOr<void> Coredump::write_elf_header()
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ErrorOr<void> Coredump::write_program_headers(size_t notes_size)
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{
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size_t offset = sizeof(ElfW(Ehdr)) + m_num_program_headers * sizeof(ElfW(Phdr));
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m_process->address_space().with([&](auto& space) {
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for (auto& region : space->region_tree().regions()) {
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for (auto& region : m_regions) {
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#if !INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS
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if (looks_like_userspace_heap_region(region))
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continue;
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if (region.looks_like_userspace_heap_region())
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continue;
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#endif
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if (region.access() == Memory::Region::Access::None)
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continue;
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if (region.access() == Memory::Region::Access::None)
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continue;
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ElfW(Phdr) phdr {};
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ElfW(Phdr) phdr {};
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phdr.p_type = PT_LOAD;
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phdr.p_offset = offset;
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phdr.p_vaddr = region.vaddr().get();
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phdr.p_paddr = 0;
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phdr.p_type = PT_LOAD;
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phdr.p_offset = offset;
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phdr.p_vaddr = region.vaddr().get();
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phdr.p_paddr = 0;
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phdr.p_filesz = region.page_count() * PAGE_SIZE;
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phdr.p_memsz = region.page_count() * PAGE_SIZE;
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phdr.p_align = 0;
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phdr.p_filesz = region.page_count() * PAGE_SIZE;
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phdr.p_memsz = region.page_count() * PAGE_SIZE;
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phdr.p_align = 0;
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phdr.p_flags = region.is_readable() ? PF_R : 0;
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if (region.is_writable())
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phdr.p_flags |= PF_W;
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if (region.is_executable())
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phdr.p_flags |= PF_X;
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phdr.p_flags = region.is_readable() ? PF_R : 0;
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if (region.is_writable())
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phdr.p_flags |= PF_W;
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if (region.is_executable())
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phdr.p_flags |= PF_X;
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offset += phdr.p_filesz;
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offset += phdr.p_filesz;
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[[maybe_unused]] auto rc = m_description->write(UserOrKernelBuffer::for_kernel_buffer(reinterpret_cast<uint8_t*>(&phdr)), sizeof(ElfW(Phdr)));
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}
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});
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[[maybe_unused]] auto rc = m_description->write(UserOrKernelBuffer::for_kernel_buffer(reinterpret_cast<uint8_t*>(&phdr)), sizeof(ElfW(Phdr)));
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}
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ElfW(Phdr) notes_pheader {};
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notes_pheader.p_type = PT_NOTE;
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@ -188,27 +209,35 @@ ErrorOr<void> Coredump::write_regions()
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{
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u8 zero_buffer[PAGE_SIZE] = {};
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return m_process->address_space().with([&](auto& space) -> ErrorOr<void> {
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for (auto& region : space->region_tree().regions()) {
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VERIFY(!region.is_kernel());
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for (auto& region : m_regions) {
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VERIFY(!region.is_kernel());
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#if !INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS
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if (looks_like_userspace_heap_region(region))
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continue;
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if (region.looks_like_userspace_heap_region())
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continue;
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#endif
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if (region.access() == Memory::Region::Access::None)
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continue;
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if (region.access() == Memory::Region::Access::None)
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continue;
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TRY(m_process->address_space().with([&](auto& space) -> ErrorOr<void> {
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auto* real_region = space->region_tree().regions().find(region.vaddr().get());
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if (!real_region)
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return Error::from_string_view("Failed to find matching region in the process"sv);
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if (!region.is_consistent_with_region(*real_region))
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return Error::from_string_view("Found region does not match stored metadata"sv);
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// If we crashed in the middle of mapping in Regions, they do not have a page directory yet, and will crash on a remap() call
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if (!region.is_mapped())
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continue;
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if (!real_region->is_mapped())
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return {};
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region.set_readable(true);
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region.remap();
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real_region->set_readable(true);
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real_region->remap();
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for (size_t i = 0; i < region.page_count(); i++) {
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auto page = region.physical_page(i);
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auto page = real_region->physical_page(i);
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auto src_buffer = [&]() -> ErrorOr<UserOrKernelBuffer> {
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if (page)
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return UserOrKernelBuffer::for_user_buffer(reinterpret_cast<uint8_t*>((region.vaddr().as_ptr() + (i * PAGE_SIZE))), PAGE_SIZE);
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@ -217,9 +246,12 @@ ErrorOr<void> Coredump::write_regions()
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}();
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TRY(m_description->write(src_buffer.value(), PAGE_SIZE));
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}
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}
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return {};
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});
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return {};
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}));
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}
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return {};
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}
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ErrorOr<void> Coredump::write_notes_segment(ReadonlyBytes notes_segment)
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@ -279,35 +311,33 @@ ErrorOr<void> Coredump::create_notes_threads_data(auto& builder) const
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ErrorOr<void> Coredump::create_notes_regions_data(auto& builder) const
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{
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size_t region_index = 0;
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return m_process->address_space().with([&](auto& space) -> ErrorOr<void> {
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for (auto const& region : space->region_tree().regions()) {
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for (auto const& region : m_regions) {
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#if !INCLUDE_USERSPACE_HEAP_MEMORY_IN_COREDUMPS
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if (looks_like_userspace_heap_region(region))
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continue;
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if (region.looks_like_userspace_heap_region())
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continue;
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#endif
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if (region.access() == Memory::Region::Access::None)
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continue;
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if (region.access() == Memory::Region::Access::None)
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continue;
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ELF::Core::MemoryRegionInfo info {};
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info.header.type = ELF::Core::NotesEntryHeader::Type::MemoryRegionInfo;
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ELF::Core::MemoryRegionInfo info {};
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info.header.type = ELF::Core::NotesEntryHeader::Type::MemoryRegionInfo;
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info.region_start = region.vaddr().get();
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info.region_end = region.vaddr().offset(region.size()).get();
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info.program_header_index = region_index++;
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info.region_start = region.vaddr().get();
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info.region_end = region.vaddr().offset(region.size()).get();
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info.program_header_index = region_index++;
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TRY(builder.append_bytes(ReadonlyBytes { (void*)&info, sizeof(info) }));
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TRY(builder.append_bytes(ReadonlyBytes { (void*)&info, sizeof(info) }));
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// NOTE: The region name *is* null-terminated, so the following is ok:
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auto name = region.name();
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if (name.is_empty())
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TRY(builder.append('\0'));
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else
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TRY(builder.append(name.characters_without_null_termination(), name.length() + 1));
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}
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return {};
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});
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// NOTE: The region name *is* null-terminated, so the following is ok:
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auto name = region.name();
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if (name.is_empty())
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TRY(builder.append('\0'));
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else
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TRY(builder.append(name.characters_without_null_termination(), name.length() + 1));
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}
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return {};
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}
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ErrorOr<void> Coredump::create_notes_metadata_data(auto& builder) const
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@ -8,8 +8,10 @@
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#pragma once
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#include <AK/OwnPtr.h>
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#include <AK/Vector.h>
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#include <Kernel/Forward.h>
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#include <Kernel/Library/NonnullLockRefPtr.h>
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#include <Kernel/Memory/Region.h>
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namespace Kernel {
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@ -21,7 +23,47 @@ public:
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ErrorOr<void> write();
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private:
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Coredump(NonnullLockRefPtr<Process>, NonnullLockRefPtr<OpenFileDescription>);
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class FlatRegionData {
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public:
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explicit FlatRegionData(Memory::Region const& region, NonnullOwnPtr<KString> name)
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: m_access(region.access())
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, m_is_executable(region.is_executable())
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, m_is_kernel(region.is_kernel())
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, m_is_readable(region.is_readable())
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, m_is_writable(region.is_writable())
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, m_name(move(name))
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, m_page_count(region.page_count())
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, m_size(region.size())
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, m_vaddr(region.vaddr())
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{
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}
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auto access() const { return m_access; }
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auto name() const { return m_name->view(); }
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auto is_executable() const { return m_is_executable; }
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auto is_kernel() const { return m_is_kernel; }
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auto is_readable() const { return m_is_readable; }
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auto is_writable() const { return m_is_writable; }
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auto page_count() const { return m_page_count; }
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auto size() const { return m_size; }
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auto vaddr() const { return m_vaddr; }
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bool looks_like_userspace_heap_region() const;
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bool is_consistent_with_region(Memory::Region const& region) const;
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private:
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Memory::Region::Access m_access;
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bool m_is_executable;
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bool m_is_kernel;
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bool m_is_readable;
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bool m_is_writable;
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NonnullOwnPtr<KString> m_name;
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size_t m_page_count;
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size_t m_size;
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VirtualAddress m_vaddr;
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};
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Coredump(NonnullLockRefPtr<Process>, NonnullLockRefPtr<OpenFileDescription>, Vector<FlatRegionData>);
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static ErrorOr<NonnullLockRefPtr<OpenFileDescription>> try_create_target_file(Process const&, StringView output_path);
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ErrorOr<void> write_elf_header();
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@ -38,6 +80,7 @@ private:
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NonnullLockRefPtr<Process> m_process;
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NonnullLockRefPtr<OpenFileDescription> m_description;
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size_t m_num_program_headers { 0 };
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Vector<FlatRegionData> m_regions;
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};
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}
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