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llvm-project/lldb/source/Plugins/DynamicLoader/Hexagon-DYLD/DynamicLoaderHexagonDYLD.cpp

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//===-- DynamicLoaderHexagonDYLD.cpp --------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "lldb/Breakpoint/BreakpointLocation.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/ModuleSpec.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/Section.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "lldb/Target/ThreadPlanRunToAddress.h"
#include "lldb/Utility/Log.h"
#include "DynamicLoaderHexagonDYLD.h"
#include <memory>
using namespace lldb;
using namespace lldb_private;
LLDB_PLUGIN_DEFINE(DynamicLoaderHexagonDYLD)
// Aidan 21/05/2014
//
// Notes about hexagon dynamic loading:
//
// When we connect to a target we find the dyld breakpoint address. We put
// a
// breakpoint there with a callback 'RendezvousBreakpointHit()'.
//
// It is possible to find the dyld structure address from the ELF symbol
// table,
// but in the case of the simulator it has not been initialized before the
// target calls dlinit().
//
// We can only safely parse the dyld structure after we hit the dyld
// breakpoint
// since at that time we know dlinit() must have been called.
//
// Find the load address of a symbol
static lldb::addr_t findSymbolAddress(Process *proc, ConstString findName) {
assert(proc != nullptr);
ModuleSP module = proc->GetTarget().GetExecutableModule();
assert(module.get() != nullptr);
ObjectFile *exe = module->GetObjectFile();
assert(exe != nullptr);
lldb_private::Symtab *symtab = exe->GetSymtab();
assert(symtab != nullptr);
for (size_t i = 0; i < symtab->GetNumSymbols(); i++) {
const Symbol *sym = symtab->SymbolAtIndex(i);
assert(sym != nullptr);
ConstString symName = sym->GetName();
if (ConstString::Compare(findName, symName) == 0) {
Address addr = sym->GetAddress();
return addr.GetLoadAddress(&proc->GetTarget());
}
}
return LLDB_INVALID_ADDRESS;
}
void DynamicLoaderHexagonDYLD::Initialize() {
PluginManager::RegisterPlugin(GetPluginNameStatic(),
GetPluginDescriptionStatic(), CreateInstance);
}
void DynamicLoaderHexagonDYLD::Terminate() {}
lldb_private::ConstString DynamicLoaderHexagonDYLD::GetPluginName() {
return GetPluginNameStatic();
}
lldb_private::ConstString DynamicLoaderHexagonDYLD::GetPluginNameStatic() {
static ConstString g_name("hexagon-dyld");
return g_name;
}
const char *DynamicLoaderHexagonDYLD::GetPluginDescriptionStatic() {
return "Dynamic loader plug-in that watches for shared library "
"loads/unloads in Hexagon processes.";
}
uint32_t DynamicLoaderHexagonDYLD::GetPluginVersion() { return 1; }
DynamicLoader *DynamicLoaderHexagonDYLD::CreateInstance(Process *process,
bool force) {
bool create = force;
if (!create) {
const llvm::Triple &triple_ref =
process->GetTarget().GetArchitecture().GetTriple();
if (triple_ref.getArch() == llvm::Triple::hexagon)
create = true;
}
if (create)
return new DynamicLoaderHexagonDYLD(process);
return nullptr;
}
DynamicLoaderHexagonDYLD::DynamicLoaderHexagonDYLD(Process *process)
: DynamicLoader(process), m_rendezvous(process),
m_load_offset(LLDB_INVALID_ADDRESS), m_entry_point(LLDB_INVALID_ADDRESS),
m_dyld_bid(LLDB_INVALID_BREAK_ID) {}
DynamicLoaderHexagonDYLD::~DynamicLoaderHexagonDYLD() {
if (m_dyld_bid != LLDB_INVALID_BREAK_ID) {
m_process->GetTarget().RemoveBreakpointByID(m_dyld_bid);
m_dyld_bid = LLDB_INVALID_BREAK_ID;
}
}
void DynamicLoaderHexagonDYLD::DidAttach() {
ModuleSP executable;
addr_t load_offset;
executable = GetTargetExecutable();
// Find the difference between the desired load address in the elf file and
// the real load address in memory
load_offset = ComputeLoadOffset();
// Check that there is a valid executable
if (executable.get() == nullptr)
return;
// Disable JIT for hexagon targets because its not supported
m_process->SetCanJIT(false);
// Enable Interpreting of function call expressions
m_process->SetCanInterpretFunctionCalls(true);
// Add the current executable to the module list
ModuleList module_list;
module_list.Append(executable);
// Map the loaded sections of this executable
if (load_offset != LLDB_INVALID_ADDRESS)
UpdateLoadedSections(executable, LLDB_INVALID_ADDRESS, load_offset, true);
// AD: confirm this?
// Load into LLDB all of the currently loaded executables in the stub
LoadAllCurrentModules();
// AD: confirm this?
// Callback for the target to give it the loaded module list
m_process->GetTarget().ModulesDidLoad(module_list);
// Try to set a breakpoint at the rendezvous breakpoint. DidLaunch uses
// ProbeEntry() instead. That sets a breakpoint, at the dyld breakpoint
// address, with a callback so that when hit, the dyld structure can be
// parsed.
if (!SetRendezvousBreakpoint()) {
// fail
}
}
void DynamicLoaderHexagonDYLD::DidLaunch() {}
/// Checks to see if the target module has changed, updates the target
/// accordingly and returns the target executable module.
ModuleSP DynamicLoaderHexagonDYLD::GetTargetExecutable() {
Target &target = m_process->GetTarget();
ModuleSP executable = target.GetExecutableModule();
// There is no executable
if (!executable.get())
return executable;
// The target executable file does not exits
if (!FileSystem::Instance().Exists(executable->GetFileSpec()))
return executable;
// Prep module for loading
ModuleSpec module_spec(executable->GetFileSpec(),
executable->GetArchitecture());
ModuleSP module_sp(new Module(module_spec));
// Check if the executable has changed and set it to the target executable if
// they differ.
if (module_sp.get() && module_sp->GetUUID().IsValid() &&
executable->GetUUID().IsValid()) {
// if the executable has changed ??
if (module_sp->GetUUID() != executable->GetUUID())
executable.reset();
} else if (executable->FileHasChanged())
executable.reset();
if (executable.get())
return executable;
// TODO: What case is this code used?
executable = target.GetOrCreateModule(module_spec, true /* notify */);
if (executable.get() != target.GetExecutableModulePointer()) {
// Don't load dependent images since we are in dyld where we will know and
// find out about all images that are loaded
target.SetExecutableModule(executable, eLoadDependentsNo);
}
return executable;
}
// AD: Needs to be updated?
Status DynamicLoaderHexagonDYLD::CanLoadImage() { return Status(); }
void DynamicLoaderHexagonDYLD::UpdateLoadedSections(ModuleSP module,
addr_t link_map_addr,
addr_t base_addr,
bool base_addr_is_offset) {
Target &target = m_process->GetTarget();
const SectionList *sections = GetSectionListFromModule(module);
assert(sections && "SectionList missing from loaded module.");
m_loaded_modules[module] = link_map_addr;
const size_t num_sections = sections->GetSize();
for (unsigned i = 0; i < num_sections; ++i) {
SectionSP section_sp(sections->GetSectionAtIndex(i));
lldb::addr_t new_load_addr = section_sp->GetFileAddress() + base_addr;
// AD: 02/05/14
// since our memory map starts from address 0, we must not ignore
// sections that load to address 0. This violates the reference
// ELF spec, however is used for Hexagon.
// If the file address of the section is zero then this is not an
// allocatable/loadable section (property of ELF sh_addr). Skip it.
// if (new_load_addr == base_addr)
// continue;
target.SetSectionLoadAddress(section_sp, new_load_addr);
}
}
/// Removes the loaded sections from the target in \p module.
///
/// \param module The module to traverse.
void DynamicLoaderHexagonDYLD::UnloadSections(const ModuleSP module) {
Target &target = m_process->GetTarget();
const SectionList *sections = GetSectionListFromModule(module);
assert(sections && "SectionList missing from unloaded module.");
m_loaded_modules.erase(module);
const size_t num_sections = sections->GetSize();
for (size_t i = 0; i < num_sections; ++i) {
SectionSP section_sp(sections->GetSectionAtIndex(i));
target.SetSectionUnloaded(section_sp);
}
}
// Place a breakpoint on <_rtld_debug_state>
bool DynamicLoaderHexagonDYLD::SetRendezvousBreakpoint() {
Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
// This is the original code, which want to look in the rendezvous structure
// to find the breakpoint address. Its backwards for us, since we can easily
// find the breakpoint address, since it is exported in our executable. We
// however know that we cant read the Rendezvous structure until we have hit
// the breakpoint once.
const ConstString dyldBpName("_rtld_debug_state");
addr_t break_addr = findSymbolAddress(m_process, dyldBpName);
Target &target = m_process->GetTarget();
// Do not try to set the breakpoint if we don't know where to put it
if (break_addr == LLDB_INVALID_ADDRESS) {
LLDB_LOGF(log, "Unable to locate _rtld_debug_state breakpoint address");
return false;
}
// Save the address of the rendezvous structure
m_rendezvous.SetBreakAddress(break_addr);
// If we haven't set the breakpoint before then set it
if (m_dyld_bid == LLDB_INVALID_BREAK_ID) {
Breakpoint *dyld_break =
target.CreateBreakpoint(break_addr, true, false).get();
dyld_break->SetCallback(RendezvousBreakpointHit, this, true);
dyld_break->SetBreakpointKind("shared-library-event");
m_dyld_bid = dyld_break->GetID();
// Make sure our breakpoint is at the right address.
assert(target.GetBreakpointByID(m_dyld_bid)
->FindLocationByAddress(break_addr)
->GetBreakpoint()
.GetID() == m_dyld_bid);
if (log && dyld_break == nullptr)
LLDB_LOGF(log, "Failed to create _rtld_debug_state breakpoint");
// check we have successfully set bp
return (dyld_break != nullptr);
} else
// rendezvous already set
return true;
}
// We have just hit our breakpoint at <_rtld_debug_state>
bool DynamicLoaderHexagonDYLD::RendezvousBreakpointHit(
void *baton, StoppointCallbackContext *context, user_id_t break_id,
user_id_t break_loc_id) {
Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
LLDB_LOGF(log, "Rendezvous breakpoint hit!");
DynamicLoaderHexagonDYLD *dyld_instance = nullptr;
dyld_instance = static_cast<DynamicLoaderHexagonDYLD *>(baton);
// if the dyld_instance is still not valid then try to locate it on the
// symbol table
if (!dyld_instance->m_rendezvous.IsValid()) {
Process *proc = dyld_instance->m_process;
const ConstString dyldStructName("_rtld_debug");
addr_t structAddr = findSymbolAddress(proc, dyldStructName);
if (structAddr != LLDB_INVALID_ADDRESS) {
dyld_instance->m_rendezvous.SetRendezvousAddress(structAddr);
LLDB_LOGF(log, "Found _rtld_debug structure @ 0x%08" PRIx64, structAddr);
} else {
LLDB_LOGF(log, "Unable to resolve the _rtld_debug structure");
}
}
dyld_instance->RefreshModules();
// Return true to stop the target, false to just let the target run.
return dyld_instance->GetStopWhenImagesChange();
}
/// Helper method for RendezvousBreakpointHit. Updates LLDB's current set
/// of loaded modules.
void DynamicLoaderHexagonDYLD::RefreshModules() {
Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
if (!m_rendezvous.Resolve())
return;
HexagonDYLDRendezvous::iterator I;
HexagonDYLDRendezvous::iterator E;
ModuleList &loaded_modules = m_process->GetTarget().GetImages();
if (m_rendezvous.ModulesDidLoad()) {
ModuleList new_modules;
E = m_rendezvous.loaded_end();
for (I = m_rendezvous.loaded_begin(); I != E; ++I) {
FileSpec file(I->path);
FileSystem::Instance().Resolve(file);
ModuleSP module_sp =
LoadModuleAtAddress(file, I->link_addr, I->base_addr, true);
if (module_sp.get()) {
loaded_modules.AppendIfNeeded(module_sp);
new_modules.Append(module_sp);
}
if (log) {
LLDB_LOGF(log, "Target is loading '%s'", I->path.c_str());
if (!module_sp.get())
LLDB_LOGF(log, "LLDB failed to load '%s'", I->path.c_str());
else
LLDB_LOGF(log, "LLDB successfully loaded '%s'", I->path.c_str());
}
}
m_process->GetTarget().ModulesDidLoad(new_modules);
}
if (m_rendezvous.ModulesDidUnload()) {
ModuleList old_modules;
E = m_rendezvous.unloaded_end();
for (I = m_rendezvous.unloaded_begin(); I != E; ++I) {
FileSpec file(I->path);
FileSystem::Instance().Resolve(file);
ModuleSpec module_spec(file);
ModuleSP module_sp = loaded_modules.FindFirstModule(module_spec);
if (module_sp.get()) {
old_modules.Append(module_sp);
UnloadSections(module_sp);
}
LLDB_LOGF(log, "Target is unloading '%s'", I->path.c_str());
}
loaded_modules.Remove(old_modules);
m_process->GetTarget().ModulesDidUnload(old_modules, false);
}
}
// AD: This is very different to the Static Loader code.
// It may be wise to look over this and its relation to stack
// unwinding.
ThreadPlanSP
DynamicLoaderHexagonDYLD::GetStepThroughTrampolinePlan(Thread &thread,
bool stop) {
ThreadPlanSP thread_plan_sp;
StackFrame *frame = thread.GetStackFrameAtIndex(0).get();
const SymbolContext &context = frame->GetSymbolContext(eSymbolContextSymbol);
Symbol *sym = context.symbol;
if (sym == nullptr || !sym->IsTrampoline())
return thread_plan_sp;
const ConstString sym_name =
sym->GetMangled().GetName(Mangled::ePreferMangled);
if (!sym_name)
return thread_plan_sp;
SymbolContextList target_symbols;
Target &target = thread.GetProcess()->GetTarget();
const ModuleList &images = target.GetImages();
images.FindSymbolsWithNameAndType(sym_name, eSymbolTypeCode, target_symbols);
size_t num_targets = target_symbols.GetSize();
if (!num_targets)
return thread_plan_sp;
typedef std::vector<lldb::addr_t> AddressVector;
AddressVector addrs;
for (size_t i = 0; i < num_targets; ++i) {
SymbolContext context;
AddressRange range;
if (target_symbols.GetContextAtIndex(i, context)) {
context.GetAddressRange(eSymbolContextEverything, 0, false, range);
lldb::addr_t addr = range.GetBaseAddress().GetLoadAddress(&target);
if (addr != LLDB_INVALID_ADDRESS)
addrs.push_back(addr);
}
}
if (addrs.size() > 0) {
AddressVector::iterator start = addrs.begin();
AddressVector::iterator end = addrs.end();
llvm::sort(start, end);
addrs.erase(std::unique(start, end), end);
thread_plan_sp =
std::make_shared<ThreadPlanRunToAddress>(thread, addrs, stop);
}
return thread_plan_sp;
}
/// Helper for the entry breakpoint callback. Resolves the load addresses
/// of all dependent modules.
void DynamicLoaderHexagonDYLD::LoadAllCurrentModules() {
HexagonDYLDRendezvous::iterator I;
HexagonDYLDRendezvous::iterator E;
ModuleList module_list;
if (!m_rendezvous.Resolve()) {
Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
LLDB_LOGF(
log,
"DynamicLoaderHexagonDYLD::%s unable to resolve rendezvous address",
__FUNCTION__);
return;
}
// The rendezvous class doesn't enumerate the main module, so track that
// ourselves here.
ModuleSP executable = GetTargetExecutable();
m_loaded_modules[executable] = m_rendezvous.GetLinkMapAddress();
for (I = m_rendezvous.begin(), E = m_rendezvous.end(); I != E; ++I) {
const char *module_path = I->path.c_str();
FileSpec file(module_path);
ModuleSP module_sp =
LoadModuleAtAddress(file, I->link_addr, I->base_addr, true);
if (module_sp.get()) {
module_list.Append(module_sp);
} else {
Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
LLDB_LOGF(log,
"DynamicLoaderHexagonDYLD::%s failed loading module %s at "
"0x%" PRIx64,
__FUNCTION__, module_path, I->base_addr);
}
}
m_process->GetTarget().ModulesDidLoad(module_list);
}
/// Computes a value for m_load_offset returning the computed address on
/// success and LLDB_INVALID_ADDRESS on failure.
addr_t DynamicLoaderHexagonDYLD::ComputeLoadOffset() {
// Here we could send a GDB packet to know the load offset
//
// send: $qOffsets#4b
// get: Text=0;Data=0;Bss=0
//
// Currently qOffsets is not supported by pluginProcessGDBRemote
//
return 0;
}
// Here we must try to read the entry point directly from the elf header. This
// is possible if the process is not relocatable or dynamically linked.
//
// an alternative is to look at the PC if we can be sure that we have connected
// when the process is at the entry point.
// I dont think that is reliable for us.
addr_t DynamicLoaderHexagonDYLD::GetEntryPoint() {
if (m_entry_point != LLDB_INVALID_ADDRESS)
return m_entry_point;
// check we have a valid process
if (m_process == nullptr)
return LLDB_INVALID_ADDRESS;
// Get the current executable module
Module &module = *(m_process->GetTarget().GetExecutableModule().get());
// Get the object file (elf file) for this module
lldb_private::ObjectFile &object = *(module.GetObjectFile());
// Check if the file is executable (ie, not shared object or relocatable)
if (object.IsExecutable()) {
// Get the entry point address for this object
lldb_private::Address entry = object.GetEntryPointAddress();
// Return the entry point address
return entry.GetFileAddress();
}
// No idea so back out
return LLDB_INVALID_ADDRESS;
}
const SectionList *DynamicLoaderHexagonDYLD::GetSectionListFromModule(
const ModuleSP module) const {
SectionList *sections = nullptr;
if (module.get()) {
ObjectFile *obj_file = module->GetObjectFile();
if (obj_file) {
sections = obj_file->GetSectionList();
}
}
return sections;
}
static int ReadInt(Process *process, addr_t addr) {
Status error;
int value = (int)process->ReadUnsignedIntegerFromMemory(
addr, sizeof(uint32_t), 0, error);
if (error.Fail())
return -1;
else
return value;
}
lldb::addr_t
DynamicLoaderHexagonDYLD::GetThreadLocalData(const lldb::ModuleSP module,
const lldb::ThreadSP thread,
lldb::addr_t tls_file_addr) {
auto it = m_loaded_modules.find(module);
if (it == m_loaded_modules.end())
return LLDB_INVALID_ADDRESS;
addr_t link_map = it->second;
if (link_map == LLDB_INVALID_ADDRESS)
return LLDB_INVALID_ADDRESS;
const HexagonDYLDRendezvous::ThreadInfo &metadata =
m_rendezvous.GetThreadInfo();
if (!metadata.valid)
return LLDB_INVALID_ADDRESS;
// Get the thread pointer.
addr_t tp = thread->GetThreadPointer();
if (tp == LLDB_INVALID_ADDRESS)
return LLDB_INVALID_ADDRESS;
// Find the module's modid.
int modid = ReadInt(m_process, link_map + metadata.modid_offset);
if (modid == -1)
return LLDB_INVALID_ADDRESS;
// Lookup the DTV structure for this thread.
addr_t dtv_ptr = tp + metadata.dtv_offset;
addr_t dtv = ReadPointer(dtv_ptr);
if (dtv == LLDB_INVALID_ADDRESS)
return LLDB_INVALID_ADDRESS;
// Find the TLS block for this module.
addr_t dtv_slot = dtv + metadata.dtv_slot_size * modid;
addr_t tls_block = ReadPointer(dtv_slot + metadata.tls_offset);
Module *mod = module.get();
Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
LLDB_LOGF(log,
"DynamicLoaderHexagonDYLD::Performed TLS lookup: "
"module=%s, link_map=0x%" PRIx64 ", tp=0x%" PRIx64
", modid=%i, tls_block=0x%" PRIx64,
mod->GetObjectName().AsCString(""), link_map, tp, modid, tls_block);
if (tls_block == LLDB_INVALID_ADDRESS)
return LLDB_INVALID_ADDRESS;
else
return tls_block + tls_file_addr;
}
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