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Differential D114967

[lldb] [Process/elf-core] Disable for FreeBSD vmcores
ClosedPublic

Authored by mgorny on Dec 2 2021, 9:36 AM.

Details

Reviewers
labath
krytarowski
emaste
Commits
rGfdc1638b5cbd: [lldb] [Process/elf-core] Disable for FreeBSD vmcores
Summary

Recognize FreeBSD vmcores (kernel core dumps) through OS ABI = 0xFF
+ ELF version = 0, and do not process them via the elf-core plugin.
While these files use ELF as a container format, they contain raw memory
dump rather than proper VM segments and therefore are not usable
to the elf-core plugin.

Diff Detail

Event Timeline

mgorny created this revision.Dec 2 2021, 9:36 AM
Herald added a subscriber: arichardson. · View Herald TranscriptDec 2 2021, 9:36 AM
mgorny requested review of this revision.Dec 2 2021, 9:36 AM
Harbormaster completed remote builds in B137159: Diff 391358.Dec 2 2021, 9:39 AM
emaste added inline comments.Dec 3 2021, 1:59 PM
lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp
67

Maybe "FreeBSD full ELF vmcore" or such? We may have three different FreeBSD vmcore formats to deal with

  1. kernel-generated ELF dumps (sysctl debug.minidump=0)
  2. kernel-generated minidumps (sysctl debug.minidump=1)
  3. minidump post-processed by (a fixed version of) https://reviews.freebsd.org/D19253
mgorny updated this revision to Diff 391808.Dec 3 2021, 9:20 PM

Try making the comment more precise.

mgorny updated this revision to Diff 391809.Dec 3 2021, 9:21 PM
mgorny marked an inline comment as done.

Fix thinko.

lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp
67

Good idea. I've changed it to use "full memory dump" to follow the Handbook, and added "raw" to make it clearer we're not talking of the converted version.

Harbormaster completed remote builds in B137488: Diff 391809.Dec 3 2021, 9:23 PM
mgorny updated this revision to Diff 391822.Dec 4 2021, 3:16 AM

Add arm64 support, simplify logic in ThreadFreeBSDKernel, handle unsupported architectures gracefully (instead of crashing).

Harbormaster completed remote builds in B137493: Diff 391822.Dec 4 2021, 3:18 AM
mgorny updated this revision to Diff 391826.Dec 4 2021, 3:47 AM

Sorry, accidentally uploaded the patch to the wrong revision.

Harbormaster completed remote builds in B137496: Diff 391826.Dec 4 2021, 3:49 AM
labath accepted this revision.Dec 6 2021, 5:30 AM
This revision is now accepted and ready to land.Dec 6 2021, 5:30 AM
Closed by commit rGfdc1638b5cbd: [lldb] [Process/elf-core] Disable for FreeBSD vmcores (authored by mgorny). · Explain WhyDec 6 2021, 5:55 AM
This revision was automatically updated to reflect the committed changes.
mgorny added a commit: rGfdc1638b5cbd: [lldb] [Process/elf-core] Disable for FreeBSD vmcores.
Herald added a project: Restricted Project. · View Herald TranscriptDec 6 2021, 5:55 AM

Revision Contents

PathSize
lldb/
source/
Plugins/
Process/
elf-core/
4 lines

Diff 391808

lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp

Show First 20 Lines • Show All 58 Lines • ▼ Show 20 Lines if (crash_file && !can_connect) {
auto data_sp = FileSystem::Instance().CreateDataBuffer( auto data_sp = FileSystem::Instance().CreateDataBuffer(
crash_file->GetPath(), header_size, 0); crash_file->GetPath(), header_size, 0);
if (data_sp && data_sp->GetByteSize() == header_size && if (data_sp && data_sp->GetByteSize() == header_size &&
elf::ELFHeader::MagicBytesMatch(data_sp->GetBytes())) { elf::ELFHeader::MagicBytesMatch(data_sp->GetBytes())) {
elf::ELFHeader elf_header; elf::ELFHeader elf_header;
DataExtractor data(data_sp, lldb::eByteOrderLittle, 4); DataExtractor data(data_sp, lldb::eByteOrderLittle, 4);
lldb::offset_t data_offset = 0; lldb::offset_t data_offset = 0;
if (elf_header.Parse(data, &data_offset)) { if (elf_header.Parse(data, &data_offset)) {
// Check whether we're dealing with a raw FreeBSD "whole memory dump"
emasteUnsubmitted
Done
ReplyInline Actions

Maybe "FreeBSD full ELF vmcore" or such? We may have three different FreeBSD vmcore formats to deal with

  1. kernel-generated ELF dumps (sysctl debug.minidump=0)
  2. kernel-generated minidumps (sysctl debug.minidump=1)
  3. minidump post-processed by (a fixed version of) https://reviews.freebsd.org/D19253
emaste: Maybe "FreeBSD full ELF vmcore" or such? We may have three different FreeBSD vmcore formats to…
mgornyAuthorUnsubmitted
Done
ReplyInline Actions

Good idea. I've changed it to use "full memory dump" to follow the Handbook, and added "raw" to make it clearer we're not talking of the converted version.

mgorny: Good idea. I've changed it to use "full memory dump" to follow the Handbook, and added "raw" to…
// ELF vmcore that needs to be handled via FreeBSDKernel plugin instead.
if (elf_header.e_ident[7] == 0xFF && elf_header.e_version == 0)
return process_sp;
if (elf_header.e_type == llvm::ELF::ET_CORE) if (elf_header.e_type == llvm::ELF::ET_CORE)
process_sp = std::make_shared<ProcessElfCore>(target_sp, listener_sp, process_sp = std::make_shared<ProcessElfCore>(target_sp, listener_sp,
*crash_file); *crash_file);
} }
} }
} }
return process_sp; return process_sp;
} }
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