1 //===-- NativeThreadLinux.cpp --------------------------------- -*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "NativeThreadLinux.h"
11 
12 #include <signal.h>
13 #include <sstream>
14 
15 #include "NativeProcessLinux.h"
16 #include "NativeRegisterContextLinux.h"
17 #include "SingleStepCheck.h"
18 
19 #include "lldb/Core/State.h"
20 #include "lldb/Host/HostNativeThread.h"
21 #include "lldb/Host/linux/Ptrace.h"
22 #include "lldb/Host/linux/Support.h"
23 #include "lldb/Utility/LLDBAssert.h"
24 #include "lldb/Utility/Log.h"
25 #include "lldb/lldb-enumerations.h"
26 
27 #include "llvm/ADT/SmallString.h"
28 
29 #include "Plugins/Process/POSIX/CrashReason.h"
30 
31 #include <sys/syscall.h>
32 // Try to define a macro to encapsulate the tgkill syscall
33 #define tgkill(pid, tid, sig)                                                  \
34   syscall(__NR_tgkill, static_cast<::pid_t>(pid), static_cast<::pid_t>(tid),   \
35           sig)
36 
37 using namespace lldb;
38 using namespace lldb_private;
39 using namespace lldb_private::process_linux;
40 
41 namespace {
42 void LogThreadStopInfo(Log &log, const ThreadStopInfo &stop_info,
43                        const char *const header) {
44   switch (stop_info.reason) {
45   case eStopReasonNone:
46     log.Printf("%s: %s no stop reason", __FUNCTION__, header);
47     return;
48   case eStopReasonTrace:
49     log.Printf("%s: %s trace, stopping signal 0x%" PRIx32, __FUNCTION__, header,
50                stop_info.details.signal.signo);
51     return;
52   case eStopReasonBreakpoint:
53     log.Printf("%s: %s breakpoint, stopping signal 0x%" PRIx32, __FUNCTION__,
54                header, stop_info.details.signal.signo);
55     return;
56   case eStopReasonWatchpoint:
57     log.Printf("%s: %s watchpoint, stopping signal 0x%" PRIx32, __FUNCTION__,
58                header, stop_info.details.signal.signo);
59     return;
60   case eStopReasonSignal:
61     log.Printf("%s: %s signal 0x%02" PRIx32, __FUNCTION__, header,
62                stop_info.details.signal.signo);
63     return;
64   case eStopReasonException:
65     log.Printf("%s: %s exception type 0x%02" PRIx64, __FUNCTION__, header,
66                stop_info.details.exception.type);
67     return;
68   case eStopReasonExec:
69     log.Printf("%s: %s exec, stopping signal 0x%" PRIx32, __FUNCTION__, header,
70                stop_info.details.signal.signo);
71     return;
72   case eStopReasonPlanComplete:
73     log.Printf("%s: %s plan complete", __FUNCTION__, header);
74     return;
75   case eStopReasonThreadExiting:
76     log.Printf("%s: %s thread exiting", __FUNCTION__, header);
77     return;
78   case eStopReasonInstrumentation:
79     log.Printf("%s: %s instrumentation", __FUNCTION__, header);
80     return;
81   default:
82     log.Printf("%s: %s invalid stop reason %" PRIu32, __FUNCTION__, header,
83                static_cast<uint32_t>(stop_info.reason));
84   }
85 }
86 }
87 
88 NativeThreadLinux::NativeThreadLinux(NativeProcessLinux &process,
89                                      lldb::tid_t tid)
90     : NativeThreadProtocol(process, tid), m_state(StateType::eStateInvalid),
91       m_stop_info(), m_reg_context_sp(), m_stop_description() {}
92 
93 std::string NativeThreadLinux::GetName() {
94   NativeProcessLinux &process = GetProcess();
95 
96   auto BufferOrError = getProcFile(process.GetID(), GetID(), "comm");
97   if (!BufferOrError)
98     return "";
99   return BufferOrError.get()->getBuffer().rtrim('\n');
100 }
101 
102 lldb::StateType NativeThreadLinux::GetState() { return m_state; }
103 
104 bool NativeThreadLinux::GetStopReason(ThreadStopInfo &stop_info,
105                                       std::string &description) {
106   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));
107 
108   description.clear();
109 
110   switch (m_state) {
111   case eStateStopped:
112   case eStateCrashed:
113   case eStateExited:
114   case eStateSuspended:
115   case eStateUnloaded:
116     if (log)
117       LogThreadStopInfo(*log, m_stop_info, "m_stop_info in thread:");
118     stop_info = m_stop_info;
119     description = m_stop_description;
120     if (log)
121       LogThreadStopInfo(*log, stop_info, "returned stop_info:");
122 
123     return true;
124 
125   case eStateInvalid:
126   case eStateConnected:
127   case eStateAttaching:
128   case eStateLaunching:
129   case eStateRunning:
130   case eStateStepping:
131   case eStateDetached:
132     if (log) {
133       log->Printf("NativeThreadLinux::%s tid %" PRIu64
134                   " in state %s cannot answer stop reason",
135                   __FUNCTION__, GetID(), StateAsCString(m_state));
136     }
137     return false;
138   }
139   llvm_unreachable("unhandled StateType!");
140 }
141 
142 NativeRegisterContextSP NativeThreadLinux::GetRegisterContext() {
143   // Return the register context if we already created it.
144   if (m_reg_context_sp)
145     return m_reg_context_sp;
146 
147   const uint32_t concrete_frame_idx = 0;
148   m_reg_context_sp.reset(
149       NativeRegisterContextLinux::CreateHostNativeRegisterContextLinux(
150           m_process.GetArchitecture(), *this, concrete_frame_idx));
151 
152   return m_reg_context_sp;
153 }
154 
155 Status NativeThreadLinux::SetWatchpoint(lldb::addr_t addr, size_t size,
156                                         uint32_t watch_flags, bool hardware) {
157   if (!hardware)
158     return Status("not implemented");
159   if (m_state == eStateLaunching)
160     return Status();
161   Status error = RemoveWatchpoint(addr);
162   if (error.Fail())
163     return error;
164   NativeRegisterContextSP reg_ctx = GetRegisterContext();
165   uint32_t wp_index = reg_ctx->SetHardwareWatchpoint(addr, size, watch_flags);
166   if (wp_index == LLDB_INVALID_INDEX32)
167     return Status("Setting hardware watchpoint failed.");
168   m_watchpoint_index_map.insert({addr, wp_index});
169   return Status();
170 }
171 
172 Status NativeThreadLinux::RemoveWatchpoint(lldb::addr_t addr) {
173   auto wp = m_watchpoint_index_map.find(addr);
174   if (wp == m_watchpoint_index_map.end())
175     return Status();
176   uint32_t wp_index = wp->second;
177   m_watchpoint_index_map.erase(wp);
178   if (GetRegisterContext()->ClearHardwareWatchpoint(wp_index))
179     return Status();
180   return Status("Clearing hardware watchpoint failed.");
181 }
182 
183 Status NativeThreadLinux::SetHardwareBreakpoint(lldb::addr_t addr,
184                                                 size_t size) {
185   if (m_state == eStateLaunching)
186     return Status();
187 
188   Status error = RemoveHardwareBreakpoint(addr);
189   if (error.Fail())
190     return error;
191 
192   NativeRegisterContextSP reg_ctx = GetRegisterContext();
193   uint32_t bp_index = reg_ctx->SetHardwareBreakpoint(addr, size);
194 
195   if (bp_index == LLDB_INVALID_INDEX32)
196     return Status("Setting hardware breakpoint failed.");
197 
198   m_hw_break_index_map.insert({addr, bp_index});
199   return Status();
200 }
201 
202 Status NativeThreadLinux::RemoveHardwareBreakpoint(lldb::addr_t addr) {
203   auto bp = m_hw_break_index_map.find(addr);
204   if (bp == m_hw_break_index_map.end())
205     return Status();
206 
207   uint32_t bp_index = bp->second;
208   if (GetRegisterContext()->ClearHardwareBreakpoint(bp_index)) {
209     m_hw_break_index_map.erase(bp);
210     return Status();
211   }
212 
213   return Status("Clearing hardware breakpoint failed.");
214 }
215 
216 Status NativeThreadLinux::Resume(uint32_t signo) {
217   const StateType new_state = StateType::eStateRunning;
218   MaybeLogStateChange(new_state);
219   m_state = new_state;
220 
221   m_stop_info.reason = StopReason::eStopReasonNone;
222   m_stop_description.clear();
223 
224   // If watchpoints have been set, but none on this thread,
225   // then this is a new thread. So set all existing watchpoints.
226   if (m_watchpoint_index_map.empty()) {
227     NativeProcessLinux &process = GetProcess();
228 
229     const auto &watchpoint_map = process.GetWatchpointMap();
230     GetRegisterContext()->ClearAllHardwareWatchpoints();
231     for (const auto &pair : watchpoint_map) {
232       const auto &wp = pair.second;
233       SetWatchpoint(wp.m_addr, wp.m_size, wp.m_watch_flags, wp.m_hardware);
234     }
235   }
236 
237   // Set all active hardware breakpoint on all threads.
238   if (m_hw_break_index_map.empty()) {
239     NativeProcessLinux &process = GetProcess();
240 
241     const auto &hw_breakpoint_map = process.GetHardwareBreakpointMap();
242     GetRegisterContext()->ClearAllHardwareBreakpoints();
243     for (const auto &pair : hw_breakpoint_map) {
244       const auto &bp = pair.second;
245       SetHardwareBreakpoint(bp.m_addr, bp.m_size);
246     }
247   }
248 
249   intptr_t data = 0;
250 
251   if (signo != LLDB_INVALID_SIGNAL_NUMBER)
252     data = signo;
253 
254   return NativeProcessLinux::PtraceWrapper(PTRACE_CONT, GetID(), nullptr,
255                                            reinterpret_cast<void *>(data));
256 }
257 
258 Status NativeThreadLinux::SingleStep(uint32_t signo) {
259   const StateType new_state = StateType::eStateStepping;
260   MaybeLogStateChange(new_state);
261   m_state = new_state;
262   m_stop_info.reason = StopReason::eStopReasonNone;
263 
264   if(!m_step_workaround) {
265     // If we already hava a workaround inplace, don't reset it. Otherwise, the
266     // destructor of the existing instance will run after the new instance has
267     // fetched the cpu mask, and the thread will end up with the wrong mask.
268     m_step_workaround = SingleStepWorkaround::Get(m_tid);
269   }
270 
271   intptr_t data = 0;
272   if (signo != LLDB_INVALID_SIGNAL_NUMBER)
273     data = signo;
274 
275   // If hardware single-stepping is not supported, we just do a continue. The
276   // breakpoint on the
277   // next instruction has been setup in NativeProcessLinux::Resume.
278   return NativeProcessLinux::PtraceWrapper(
279       GetProcess().SupportHardwareSingleStepping() ? PTRACE_SINGLESTEP
280                                                    : PTRACE_CONT,
281       m_tid, nullptr, reinterpret_cast<void *>(data));
282 }
283 
284 void NativeThreadLinux::SetStoppedBySignal(uint32_t signo,
285                                            const siginfo_t *info) {
286   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));
287   if (log)
288     log->Printf("NativeThreadLinux::%s called with signal 0x%02" PRIx32,
289                 __FUNCTION__, signo);
290 
291   SetStopped();
292 
293   m_stop_info.reason = StopReason::eStopReasonSignal;
294   m_stop_info.details.signal.signo = signo;
295 
296   m_stop_description.clear();
297   if (info) {
298     switch (signo) {
299     case SIGSEGV:
300     case SIGBUS:
301     case SIGFPE:
302     case SIGILL:
303       // In case of MIPS64 target, SI_KERNEL is generated for invalid 64bit
304       // address.
305       const auto reason =
306           (info->si_signo == SIGBUS && info->si_code == SI_KERNEL)
307               ? CrashReason::eInvalidAddress
308               : GetCrashReason(*info);
309       m_stop_description = GetCrashReasonString(reason, *info);
310       break;
311     }
312   }
313 }
314 
315 bool NativeThreadLinux::IsStopped(int *signo) {
316   if (!StateIsStoppedState(m_state, false))
317     return false;
318 
319   // If we are stopped by a signal, return the signo.
320   if (signo && m_state == StateType::eStateStopped &&
321       m_stop_info.reason == StopReason::eStopReasonSignal) {
322     *signo = m_stop_info.details.signal.signo;
323   }
324 
325   // Regardless, we are stopped.
326   return true;
327 }
328 
329 void NativeThreadLinux::SetStopped() {
330   if (m_state == StateType::eStateStepping)
331     m_step_workaround.reset();
332 
333   const StateType new_state = StateType::eStateStopped;
334   MaybeLogStateChange(new_state);
335   m_state = new_state;
336   m_stop_description.clear();
337 }
338 
339 void NativeThreadLinux::SetStoppedByExec() {
340   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));
341   if (log)
342     log->Printf("NativeThreadLinux::%s()", __FUNCTION__);
343 
344   SetStopped();
345 
346   m_stop_info.reason = StopReason::eStopReasonExec;
347   m_stop_info.details.signal.signo = SIGSTOP;
348 }
349 
350 void NativeThreadLinux::SetStoppedByBreakpoint() {
351   SetStopped();
352 
353   m_stop_info.reason = StopReason::eStopReasonBreakpoint;
354   m_stop_info.details.signal.signo = SIGTRAP;
355   m_stop_description.clear();
356 }
357 
358 void NativeThreadLinux::SetStoppedByWatchpoint(uint32_t wp_index) {
359   SetStopped();
360 
361   lldbassert(wp_index != LLDB_INVALID_INDEX32 && "wp_index cannot be invalid");
362 
363   std::ostringstream ostr;
364   ostr << GetRegisterContext()->GetWatchpointAddress(wp_index) << " ";
365   ostr << wp_index;
366 
367   /*
368    * MIPS: Last 3bits of the watchpoint address are masked by the kernel. For
369    * example:
370    * 'n' is at 0x120010d00 and 'm' is 0x120010d04. When a watchpoint is set at
371    * 'm', then
372    * watch exception is generated even when 'n' is read/written. To handle this
373    * case,
374    * find the base address of the load/store instruction and append it in the
375    * stop-info
376    * packet.
377   */
378   ostr << " " << GetRegisterContext()->GetWatchpointHitAddress(wp_index);
379 
380   m_stop_description = ostr.str();
381 
382   m_stop_info.reason = StopReason::eStopReasonWatchpoint;
383   m_stop_info.details.signal.signo = SIGTRAP;
384 }
385 
386 bool NativeThreadLinux::IsStoppedAtBreakpoint() {
387   return GetState() == StateType::eStateStopped &&
388          m_stop_info.reason == StopReason::eStopReasonBreakpoint;
389 }
390 
391 bool NativeThreadLinux::IsStoppedAtWatchpoint() {
392   return GetState() == StateType::eStateStopped &&
393          m_stop_info.reason == StopReason::eStopReasonWatchpoint;
394 }
395 
396 void NativeThreadLinux::SetStoppedByTrace() {
397   SetStopped();
398 
399   m_stop_info.reason = StopReason::eStopReasonTrace;
400   m_stop_info.details.signal.signo = SIGTRAP;
401 }
402 
403 void NativeThreadLinux::SetStoppedWithNoReason() {
404   SetStopped();
405 
406   m_stop_info.reason = StopReason::eStopReasonNone;
407   m_stop_info.details.signal.signo = 0;
408 }
409 
410 void NativeThreadLinux::SetExited() {
411   const StateType new_state = StateType::eStateExited;
412   MaybeLogStateChange(new_state);
413   m_state = new_state;
414 
415   m_stop_info.reason = StopReason::eStopReasonThreadExiting;
416 }
417 
418 Status NativeThreadLinux::RequestStop() {
419   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));
420 
421   NativeProcessLinux &process = GetProcess();
422 
423   lldb::pid_t pid = process.GetID();
424   lldb::tid_t tid = GetID();
425 
426   if (log)
427     log->Printf("NativeThreadLinux::%s requesting thread stop(pid: %" PRIu64
428                 ", tid: %" PRIu64 ")",
429                 __FUNCTION__, pid, tid);
430 
431   Status err;
432   errno = 0;
433   if (::tgkill(pid, tid, SIGSTOP) != 0) {
434     err.SetErrorToErrno();
435     if (log)
436       log->Printf("NativeThreadLinux::%s tgkill(%" PRIu64 ", %" PRIu64
437                   ", SIGSTOP) failed: %s",
438                   __FUNCTION__, pid, tid, err.AsCString());
439   }
440 
441   return err;
442 }
443 
444 void NativeThreadLinux::MaybeLogStateChange(lldb::StateType new_state) {
445   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));
446   // If we're not logging, we're done.
447   if (!log)
448     return;
449 
450   // If this is a state change to the same state, we're done.
451   lldb::StateType old_state = m_state;
452   if (new_state == old_state)
453     return;
454 
455   LLDB_LOG(log, "pid={0}, tid={1}: changing from state {2} to {3}",
456            m_process.GetID(), GetID(), old_state, new_state);
457 }
458 
459 NativeProcessLinux &NativeThreadLinux::GetProcess() {
460   return static_cast<NativeProcessLinux &>(m_process);
461 }
462