1 //===-- FunctionCaller.cpp ------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 
10 #include "lldb/Expression/FunctionCaller.h"
11 #include "lldb/Core/Module.h"
12 #include "lldb/Core/ValueObject.h"
13 #include "lldb/Core/ValueObjectList.h"
14 #include "lldb/Expression/DiagnosticManager.h"
15 #include "lldb/Expression/IRExecutionUnit.h"
16 #include "lldb/Interpreter/CommandReturnObject.h"
17 #include "lldb/Symbol/Function.h"
18 #include "lldb/Symbol/Type.h"
19 #include "lldb/Target/ExecutionContext.h"
20 #include "lldb/Target/Process.h"
21 #include "lldb/Target/RegisterContext.h"
22 #include "lldb/Target/Target.h"
23 #include "lldb/Target/Thread.h"
24 #include "lldb/Target/ThreadPlan.h"
25 #include "lldb/Target/ThreadPlanCallFunction.h"
26 #include "lldb/Utility/DataExtractor.h"
27 #include "lldb/Utility/LLDBLog.h"
28 #include "lldb/Utility/Log.h"
29 #include "lldb/Utility/State.h"
30 
31 using namespace lldb_private;
32 
33 char FunctionCaller::ID;
34 
35 // FunctionCaller constructor
36 FunctionCaller::FunctionCaller(ExecutionContextScope &exe_scope,
37                                const CompilerType &return_type,
38                                const Address &functionAddress,
39                                const ValueList &arg_value_list,
40                                const char *name)
41     : Expression(exe_scope), m_execution_unit_sp(), m_parser(),
42       m_jit_module_wp(), m_name(name ? name : "<unknown>"),
43       m_function_ptr(nullptr), m_function_addr(functionAddress),
44       m_function_return_type(return_type),
45       m_wrapper_function_name("__lldb_caller_function"),
46       m_wrapper_struct_name("__lldb_caller_struct"), m_wrapper_args_addrs(),
47       m_struct_valid(false), m_struct_size(0), m_return_size(0),
48       m_return_offset(0), m_arg_values(arg_value_list), m_compiled(false),
49       m_JITted(false) {
50   m_jit_process_wp = lldb::ProcessWP(exe_scope.CalculateProcess());
51   // Can't make a FunctionCaller without a process.
52   assert(m_jit_process_wp.lock());
53 }
54 
55 // Destructor
56 FunctionCaller::~FunctionCaller() {
57   lldb::ProcessSP process_sp(m_jit_process_wp.lock());
58   if (process_sp) {
59     lldb::ModuleSP jit_module_sp(m_jit_module_wp.lock());
60     if (jit_module_sp)
61       process_sp->GetTarget().GetImages().Remove(jit_module_sp);
62   }
63 }
64 
65 bool FunctionCaller::WriteFunctionWrapper(
66     ExecutionContext &exe_ctx, DiagnosticManager &diagnostic_manager) {
67   Process *process = exe_ctx.GetProcessPtr();
68 
69   if (!process) {
70     diagnostic_manager.Printf(eDiagnosticSeverityError, "no process.");
71     return false;
72   }
73 
74   lldb::ProcessSP jit_process_sp(m_jit_process_wp.lock());
75 
76   if (process != jit_process_sp.get()) {
77     diagnostic_manager.Printf(eDiagnosticSeverityError,
78                              "process does not match the stored process.");
79     return false;
80   }
81 
82   if (process->GetState() != lldb::eStateStopped) {
83     diagnostic_manager.Printf(eDiagnosticSeverityError,
84                               "process is not stopped");
85     return false;
86   }
87 
88   if (!m_compiled) {
89     diagnostic_manager.Printf(eDiagnosticSeverityError,
90                               "function not compiled");
91     return false;
92   }
93 
94   if (m_JITted)
95     return true;
96 
97   bool can_interpret = false; // should stay that way
98 
99   Status jit_error(m_parser->PrepareForExecution(
100       m_jit_start_addr, m_jit_end_addr, m_execution_unit_sp, exe_ctx,
101       can_interpret, eExecutionPolicyAlways));
102 
103   if (!jit_error.Success()) {
104     diagnostic_manager.Printf(eDiagnosticSeverityError,
105                               "Error in PrepareForExecution: %s.",
106                               jit_error.AsCString());
107     return false;
108   }
109 
110   if (m_parser->GetGenerateDebugInfo()) {
111     lldb::ModuleSP jit_module_sp(m_execution_unit_sp->GetJITModule());
112 
113     if (jit_module_sp) {
114       ConstString const_func_name(FunctionName());
115       FileSpec jit_file;
116       jit_file.SetFilename(const_func_name);
117       jit_module_sp->SetFileSpecAndObjectName(jit_file, ConstString());
118       m_jit_module_wp = jit_module_sp;
119       process->GetTarget().GetImages().Append(jit_module_sp,
120                                               true /* notify */);
121     }
122   }
123   if (process && m_jit_start_addr)
124     m_jit_process_wp = process->shared_from_this();
125 
126   m_JITted = true;
127 
128   return true;
129 }
130 
131 bool FunctionCaller::WriteFunctionArguments(
132     ExecutionContext &exe_ctx, lldb::addr_t &args_addr_ref,
133     DiagnosticManager &diagnostic_manager) {
134   return WriteFunctionArguments(exe_ctx, args_addr_ref, m_arg_values,
135                                 diagnostic_manager);
136 }
137 
138 // FIXME: Assure that the ValueList we were passed in is consistent with the one
139 // that defined this function.
140 
141 bool FunctionCaller::WriteFunctionArguments(
142     ExecutionContext &exe_ctx, lldb::addr_t &args_addr_ref,
143     ValueList &arg_values, DiagnosticManager &diagnostic_manager) {
144   // All the information to reconstruct the struct is provided by the
145   // StructExtractor.
146   if (!m_struct_valid) {
147     diagnostic_manager.PutString(eDiagnosticSeverityError,
148                                  "Argument information was not correctly "
149                                  "parsed, so the function cannot be called.");
150     return false;
151   }
152 
153   Status error;
154   lldb::ExpressionResults return_value = lldb::eExpressionSetupError;
155 
156   Process *process = exe_ctx.GetProcessPtr();
157 
158   if (process == nullptr)
159     return return_value;
160 
161   lldb::ProcessSP jit_process_sp(m_jit_process_wp.lock());
162 
163   if (process != jit_process_sp.get())
164     return false;
165 
166   if (args_addr_ref == LLDB_INVALID_ADDRESS) {
167     args_addr_ref = process->AllocateMemory(
168         m_struct_size, lldb::ePermissionsReadable | lldb::ePermissionsWritable,
169         error);
170     if (args_addr_ref == LLDB_INVALID_ADDRESS)
171       return false;
172     m_wrapper_args_addrs.push_back(args_addr_ref);
173   } else {
174     // Make sure this is an address that we've already handed out.
175     if (find(m_wrapper_args_addrs.begin(), m_wrapper_args_addrs.end(),
176              args_addr_ref) == m_wrapper_args_addrs.end()) {
177       return false;
178     }
179   }
180 
181   // TODO: verify fun_addr needs to be a callable address
182   Scalar fun_addr(
183       m_function_addr.GetCallableLoadAddress(exe_ctx.GetTargetPtr()));
184   uint64_t first_offset = m_member_offsets[0];
185   process->WriteScalarToMemory(args_addr_ref + first_offset, fun_addr,
186                                process->GetAddressByteSize(), error);
187 
188   // FIXME: We will need to extend this for Variadic functions.
189 
190   Status value_error;
191 
192   size_t num_args = arg_values.GetSize();
193   if (num_args != m_arg_values.GetSize()) {
194     diagnostic_manager.Printf(
195         eDiagnosticSeverityError,
196         "Wrong number of arguments - was: %" PRIu64 " should be: %" PRIu64 "",
197         (uint64_t)num_args, (uint64_t)m_arg_values.GetSize());
198     return false;
199   }
200 
201   for (size_t i = 0; i < num_args; i++) {
202     // FIXME: We should sanity check sizes.
203 
204     uint64_t offset = m_member_offsets[i + 1]; // Clang sizes are in bytes.
205     Value *arg_value = arg_values.GetValueAtIndex(i);
206 
207     // FIXME: For now just do scalars:
208 
209     // Special case: if it's a pointer, don't do anything (the ABI supports
210     // passing cstrings)
211 
212     if (arg_value->GetValueType() == Value::ValueType::HostAddress &&
213         arg_value->GetContextType() == Value::ContextType::Invalid &&
214         arg_value->GetCompilerType().IsPointerType())
215       continue;
216 
217     const Scalar &arg_scalar = arg_value->ResolveValue(&exe_ctx);
218 
219     if (!process->WriteScalarToMemory(args_addr_ref + offset, arg_scalar,
220                                       arg_scalar.GetByteSize(), error))
221       return false;
222   }
223 
224   return true;
225 }
226 
227 bool FunctionCaller::InsertFunction(ExecutionContext &exe_ctx,
228                                     lldb::addr_t &args_addr_ref,
229                                     DiagnosticManager &diagnostic_manager) {
230   // Since we might need to call allocate memory and maybe call code to make
231   // the caller, we need to be stopped.
232   Process *process = exe_ctx.GetProcessPtr();
233   if (!process) {
234     diagnostic_manager.PutString(eDiagnosticSeverityError, "no process");
235     return false;
236   }
237   if (process->GetState() != lldb::eStateStopped) {
238     diagnostic_manager.PutString(eDiagnosticSeverityError, "process running");
239     return false;
240   }
241   if (CompileFunction(exe_ctx.GetThreadSP(), diagnostic_manager) != 0)
242     return false;
243   if (!WriteFunctionWrapper(exe_ctx, diagnostic_manager))
244     return false;
245   if (!WriteFunctionArguments(exe_ctx, args_addr_ref, diagnostic_manager))
246     return false;
247 
248   Log *log = GetLog(LLDBLog::Step);
249   LLDB_LOGF(log, "Call Address: 0x%" PRIx64 " Struct Address: 0x%" PRIx64 ".\n",
250             m_jit_start_addr, args_addr_ref);
251 
252   return true;
253 }
254 
255 lldb::ThreadPlanSP FunctionCaller::GetThreadPlanToCallFunction(
256     ExecutionContext &exe_ctx, lldb::addr_t args_addr,
257     const EvaluateExpressionOptions &options,
258     DiagnosticManager &diagnostic_manager) {
259   Log *log(GetLog(LLDBLog::Expressions | LLDBLog::Step));
260 
261   LLDB_LOGF(log,
262             "-- [FunctionCaller::GetThreadPlanToCallFunction] Creating "
263             "thread plan to call function \"%s\" --",
264             m_name.c_str());
265 
266   // FIXME: Use the errors Stream for better error reporting.
267   Thread *thread = exe_ctx.GetThreadPtr();
268   if (thread == nullptr) {
269     diagnostic_manager.PutString(
270         eDiagnosticSeverityError,
271         "Can't call a function without a valid thread.");
272     return nullptr;
273   }
274 
275   // Okay, now run the function:
276 
277   Address wrapper_address(m_jit_start_addr);
278 
279   lldb::addr_t args = {args_addr};
280 
281   lldb::ThreadPlanSP new_plan_sp(new ThreadPlanCallFunction(
282       *thread, wrapper_address, CompilerType(), args, options));
283   new_plan_sp->SetIsControllingPlan(true);
284   new_plan_sp->SetOkayToDiscard(false);
285   return new_plan_sp;
286 }
287 
288 bool FunctionCaller::FetchFunctionResults(ExecutionContext &exe_ctx,
289                                           lldb::addr_t args_addr,
290                                           Value &ret_value) {
291   // Read the return value - it is the last field in the struct:
292   // FIXME: How does clang tell us there's no return value?  We need to handle
293   // that case.
294   // FIXME: Create our ThreadPlanCallFunction with the return CompilerType, and
295   // then use GetReturnValueObject
296   // to fetch the value.  That way we can fetch any values we need.
297 
298   Log *log(GetLog(LLDBLog::Expressions | LLDBLog::Step));
299 
300   LLDB_LOGF(log,
301             "-- [FunctionCaller::FetchFunctionResults] Fetching function "
302             "results for \"%s\"--",
303             m_name.c_str());
304 
305   Process *process = exe_ctx.GetProcessPtr();
306 
307   if (process == nullptr)
308     return false;
309 
310   lldb::ProcessSP jit_process_sp(m_jit_process_wp.lock());
311 
312   if (process != jit_process_sp.get())
313     return false;
314 
315   Status error;
316   ret_value.GetScalar() = process->ReadUnsignedIntegerFromMemory(
317       args_addr + m_return_offset, m_return_size, 0, error);
318 
319   if (error.Fail())
320     return false;
321 
322   ret_value.SetCompilerType(m_function_return_type);
323   ret_value.SetValueType(Value::ValueType::Scalar);
324   return true;
325 }
326 
327 void FunctionCaller::DeallocateFunctionResults(ExecutionContext &exe_ctx,
328                                                lldb::addr_t args_addr) {
329   std::list<lldb::addr_t>::iterator pos;
330   pos = std::find(m_wrapper_args_addrs.begin(), m_wrapper_args_addrs.end(),
331                   args_addr);
332   if (pos != m_wrapper_args_addrs.end())
333     m_wrapper_args_addrs.erase(pos);
334 
335   exe_ctx.GetProcessRef().DeallocateMemory(args_addr);
336 }
337 
338 lldb::ExpressionResults FunctionCaller::ExecuteFunction(
339     ExecutionContext &exe_ctx, lldb::addr_t *args_addr_ptr,
340     const EvaluateExpressionOptions &options,
341     DiagnosticManager &diagnostic_manager, Value &results) {
342   lldb::ExpressionResults return_value = lldb::eExpressionSetupError;
343 
344   // FunctionCaller::ExecuteFunction execution is always just to get the
345   // result. Unless explicitly asked for, ignore breakpoints and unwind on
346   // error.
347   const bool enable_debugging =
348       exe_ctx.GetTargetPtr() &&
349       exe_ctx.GetTargetPtr()->GetDebugUtilityExpression();
350   EvaluateExpressionOptions real_options = options;
351   real_options.SetDebug(false); // This halts the expression for debugging.
352   real_options.SetGenerateDebugInfo(enable_debugging);
353   real_options.SetUnwindOnError(!enable_debugging);
354   real_options.SetIgnoreBreakpoints(!enable_debugging);
355 
356   lldb::addr_t args_addr;
357 
358   if (args_addr_ptr != nullptr)
359     args_addr = *args_addr_ptr;
360   else
361     args_addr = LLDB_INVALID_ADDRESS;
362 
363   if (CompileFunction(exe_ctx.GetThreadSP(), diagnostic_manager) != 0)
364     return lldb::eExpressionSetupError;
365 
366   if (args_addr == LLDB_INVALID_ADDRESS) {
367     if (!InsertFunction(exe_ctx, args_addr, diagnostic_manager))
368       return lldb::eExpressionSetupError;
369   }
370 
371   Log *log(GetLog(LLDBLog::Expressions | LLDBLog::Step));
372 
373   LLDB_LOGF(log,
374             "== [FunctionCaller::ExecuteFunction] Executing function \"%s\" ==",
375             m_name.c_str());
376 
377   lldb::ThreadPlanSP call_plan_sp = GetThreadPlanToCallFunction(
378       exe_ctx, args_addr, real_options, diagnostic_manager);
379   if (!call_plan_sp)
380     return lldb::eExpressionSetupError;
381 
382   // We need to make sure we record the fact that we are running an expression
383   // here otherwise this fact will fail to be recorded when fetching an
384   // Objective-C object description
385   if (exe_ctx.GetProcessPtr())
386     exe_ctx.GetProcessPtr()->SetRunningUserExpression(true);
387 
388   return_value = exe_ctx.GetProcessRef().RunThreadPlan(
389       exe_ctx, call_plan_sp, real_options, diagnostic_manager);
390 
391   if (log) {
392     if (return_value != lldb::eExpressionCompleted) {
393       LLDB_LOGF(log,
394                 "== [FunctionCaller::ExecuteFunction] Execution of \"%s\" "
395                 "completed abnormally: %s ==",
396                 m_name.c_str(),
397                 Process::ExecutionResultAsCString(return_value));
398     } else {
399       LLDB_LOGF(log,
400                 "== [FunctionCaller::ExecuteFunction] Execution of \"%s\" "
401                 "completed normally ==",
402                 m_name.c_str());
403     }
404   }
405 
406   if (exe_ctx.GetProcessPtr())
407     exe_ctx.GetProcessPtr()->SetRunningUserExpression(false);
408 
409   if (args_addr_ptr != nullptr)
410     *args_addr_ptr = args_addr;
411 
412   if (return_value != lldb::eExpressionCompleted)
413     return return_value;
414 
415   FetchFunctionResults(exe_ctx, args_addr, results);
416 
417   if (args_addr_ptr == nullptr)
418     DeallocateFunctionResults(exe_ctx, args_addr);
419 
420   return lldb::eExpressionCompleted;
421 }
422