https://github.com/jasonmolenda created
https://github.com/llvm/llvm-project/pull/136065
This patch is making three changes, when loading a Mach-O corefile:
1. At the start of `DoLoadCore`, if a binary was provided in addition to the
corefile, initialize the Target's ArchSpec.
2. Before ProcessMachCore does its "exhaustive search" fallback, looking
through the corefile contents for a userland dyld or mach kernel, we must make
sure the Target has an ArchSpec, or methods that check the address word size,
or initialize a DataExtractor based on the Target arch will not succeed.
3. Add logging when setting the Target's arch listing exactly what that setting
was based on -- the corefile itself, or the main binary.
Jonas landed a change last August (started with a patch from me) which removed
the Target ArchSpec initialization at the start of DoLoadCore, in a scenario
where the corefile had arch armv7 and the main binary had arch armv7em
(Cortex-M), and there was python code in the main binary's dSYM which sets the
operating system threads provider based on the Target arch. It did different
things for armv7 or armv7em, and so it would fail.
Jonas' patch removed any ArchSpec setting at the start of DoLoadCore, so we
wouldn't have an incorrect arch value, but that broke the exhaustive search for
kernel binaries, because we didn't have an address word size or endianness.
This patch should navigate the needs of both use cases.
I spent a good bit of time trying to construct a test to capture all of these
requirements -- but it turns out to be a good bit difficult, encompassing both
a genuine kernel corefiles and a microcontroller firmware corefiles.
rdar://146821929
>From 41274f7632d13ab7ec83a420c6ad6258e6fe8c36 Mon Sep 17 00:00:00 2001
From: Jason Molenda <jmole...@apple.com>
Date: Wed, 16 Apr 2025 17:18:02 -0700
Subject: [PATCH] [lldb][Mach-O corefiles] Don't init Target arch to corefile
This patch is making three changes, when loading a Mach-O
corefile:
1. At the start of `DoLoadCore`, if a binary was provided in addition
to the corefile, initialize the Target's ArchSpec.
2. Before ProcessMachCore does its "exhaustive search" fallback,
looking through the corefile contents for a userland dyld or mach
kernel, we must make sure the Target has an ArchSpec, or methods
that check the address word size, or initialize a DataExtractor
based on the Target arch will not succeed.
3. Add logging when setting the Target's arch listing exactly what
that setting was based on -- the corefile itself, or the main binary.
Jonas landed a change last August (started with a patch from me)
which removed the Target ArchSpec initialization at the start of
DoLoadCore, in a scenario where the corefile had arch armv7 and
the main binary had arch armv7em (Cortex-M), and there was python
code in the main binary's dSYM which sets the operating system threads
provider based on the Target arch. It did different things for
armv7 or armv7em, and so it would fail.
Jonas' patch removed any ArchSpec setting at the start of DoLoadCore,
so we wouldn't have an incorrect arch value, but that broke the
exhaustive search for kernel binaries, because we didn't have an
address word size or endianness.
This patch should navigate the needs of both use cases.
I spent a good bit of time trying to construct a test to capture all
of these requirements -- but it turns out to be a good bit difficult,
encompassing both a genuine kernel corefiles and a microcontroller
firmware corefiles.
rdar://146821929
---
.../Process/mach-core/ProcessMachCore.cpp | 58 ++++++++++++++++++-
1 file changed, 56 insertions(+), 2 deletions(-)
diff --git a/lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp
b/lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp
index 281f3a0db8f69..17362b2d2855d 100644
--- a/lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp
+++ b/lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp
@@ -426,6 +426,32 @@ void ProcessMachCore::LoadBinariesViaExhaustiveSearch() {
std::vector<addr_t> dylds_found;
std::vector<addr_t> kernels_found;
+ // To do an exhaustive search, we'll need to create data extractors
+ // to get correctly sized/endianness fields, and if the Target still
+ // doesn't have an architecture set, we need to seed it from either
+ // the main binary (if we were given one) or the corefile cputype/cpusubtype.
+ if (!GetTarget().GetArchitecture().IsValid()) {
+ Log *log(GetLog(LLDBLog::DynamicLoader | LLDBLog::Target));
+ ModuleSP exe_module_sp = GetTarget().GetExecutableModule();
+ if (exe_module_sp && exe_module_sp->GetArchitecture().IsValid()) {
+ LLDB_LOGF(log,
+ "ProcessMachCore::%s: Was given binary + corefile, setting "
+ "target ArchSpec to binary to start",
+ __FUNCTION__);
+ GetTarget().SetArchitecture(exe_module_sp->GetArchitecture());
+ } else {
+ // The corefile's architecture is our best starting point.
+ ArchSpec arch(m_core_module_sp->GetArchitecture());
+ if (arch.IsValid()) {
+ LLDB_LOGF(log,
+ "ProcessMachCore::%s: Setting target ArchSpec based on "
+ "corefile mach-o cputype/cpusubtype",
+ __FUNCTION__);
+ GetTarget().SetArchitecture(arch);
+ }
+ }
+ }
+
const size_t num_core_aranges = m_core_aranges.GetSize();
for (size_t i = 0; i < num_core_aranges; ++i) {
const VMRangeToFileOffset::Entry *entry =
m_core_aranges.GetEntryAtIndex(i);
@@ -569,6 +595,7 @@ Status ProcessMachCore::DoLoadCore() {
error = Status::FromErrorString("invalid core module");
return error;
}
+ Log *log(GetLog(LLDBLog::DynamicLoader | LLDBLog::Target));
ObjectFile *core_objfile = m_core_module_sp->GetObjectFile();
if (core_objfile == nullptr) {
@@ -578,20 +605,47 @@ Status ProcessMachCore::DoLoadCore() {
SetCanJIT(false);
+ // If we have an executable binary in the Target already,
+ // use that to set the Target's ArchSpec.
+ //
+ // Don't initialize the ArchSpec based on the corefile's cputype/cpusubtype
+ // here, the corefile creator may not know the correct subtype of the code
+ // that is executing, initialize the Target to that, and if the
+ // main binary has Python code which initializes based on the Target arch,
+ // get the wrong subtype value.
+ ModuleSP exe_module_sp = GetTarget().GetExecutableModule();
+ if (exe_module_sp && exe_module_sp->GetArchitecture().IsValid()) {
+ LLDB_LOGF(log,
+ "ProcessMachCore::%s: Was given binary + corefile, setting "
+ "target ArchSpec to binary to start",
+ __FUNCTION__);
+ GetTarget().SetArchitecture(exe_module_sp->GetArchitecture());
+ }
+
CreateMemoryRegions();
LoadBinariesAndSetDYLD();
CleanupMemoryRegionPermissions();
- ModuleSP exe_module_sp = GetTarget().GetExecutableModule();
+ exe_module_sp = GetTarget().GetExecutableModule();
if (exe_module_sp && exe_module_sp->GetArchitecture().IsValid()) {
+ LLDB_LOGF(log,
+ "ProcessMachCore::%s: have executable binary in the Target "
+ "after metadata/scan. Setting Target's ArchSpec based on "
+ "that.",
+ __FUNCTION__);
GetTarget().SetArchitecture(exe_module_sp->GetArchitecture());
} else {
// The corefile's architecture is our best starting point.
ArchSpec arch(m_core_module_sp->GetArchitecture());
- if (arch.IsValid())
+ if (arch.IsValid()) {
+ LLDB_LOGF(log,
+ "ProcessMachCore::%s: Setting target ArchSpec based on "
+ "corefile mach-o cputype/cpusubtype",
+ __FUNCTION__);
GetTarget().SetArchitecture(arch);
+ }
}
AddressableBits addressable_bits = core_objfile->GetAddressableBits();
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