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