[compiler-rt] Cleanup SignalContext initialization

compiler-rt/lib/asan/asan_posix.cc

 #include <sys/resource.h>
 #include <unistd.h>
 
 namespace __asan {
 
 void AsanOnDeadlySignal(int signo, void *siginfo, void *context) {
   ScopedDeadlySignal signal_scope(GetCurrentThread());
   StartReportDeadlySignal();
-  SignalContext sig = SignalContext::Create(siginfo, context);
+  SignalContext sig(siginfo, context);
   if (IsStackOverflow(sig))
     ReportStackOverflow(sig);
   else
     ReportDeadlySignal(sig);
 }
 
 // ---------------------- TSD ---------------- {{{1
 

compiler-rt/lib/asan/asan_win.cc

 
 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 long __asan_unhandled_exception_filter(EXCEPTION_POINTERS *info) {
   EXCEPTION_RECORD *exception_record = info->ExceptionRecord;
   CONTEXT *context = info->ContextRecord;
 
   // FIXME: Handle EXCEPTION_STACK_OVERFLOW here.
 
-  SignalContext sig = SignalContext::Create(exception_record, context);
+  SignalContext sig(exception_record, context);
   ReportDeadlySignal(sig);
   UNREACHABLE("returned from reporting deadly signal");
 }
 
 // Wrapper SEH Handler. If the exception should be handled by asan, we call
 // __asan_unhandled_exception_filter, otherwise, we execute the user provided
 // exception handler or the default.
 static long WINAPI SEHHandler(EXCEPTION_POINTERS *info) {

compiler-rt/lib/sanitizer_common/sanitizer_common.h

 struct SignalContext {
   void *siginfo;
   void *context;
   uptr addr;
   uptr pc;
   uptr sp;
   uptr bp;
   bool is_memory_access;
-
   enum WriteFlag { UNKNOWN, READ, WRITE } write_flag;
 
   // VS2013 doesn't implement unrestricted unions, so we need a trivial default
   // constructor
   SignalContext() = default;
+
+  // Creates signal context in a platform-specific manner.
   // SignalContext is going to keep pointers to siginfo and context without
   // owning them.
-  SignalContext(void *siginfo, void *context, uptr addr, uptr pc, uptr sp,
-                uptr bp, bool is_memory_access, WriteFlag write_flag)
+  SignalContext(void *siginfo, void *context)
       : siginfo(siginfo),
         context(context),
-        addr(addr),
-        pc(pc),
-        sp(sp),
-        bp(bp),
-        is_memory_access(is_memory_access),
-        write_flag(write_flag) {}
+        addr(GetAddress()),
+        is_memory_access(IsMemoryAccess()),
+        write_flag(GetWriteFlag()) {
+    InitPcSpBp();
+  }
 
   static void DumpAllRegisters(void *context);
 
-  // Creates signal context in a platform-specific manner.
-  static SignalContext Create(void *siginfo, void *context);
-
-  // Returns true if the "context" indicates a memory write.
-  static WriteFlag GetWriteFlag(void *context);
-
   // Type of signal e.g. SIGSEGV or EXCEPTION_ACCESS_VIOLATION.
   int GetType() const;
 
   // String description of the signal.
   const char *Describe() const;
-};
 
-void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp);
+ private:
+  // Platform specific initialization.
+  void InitPcSpBp();
+  uptr GetAddress() const;
+  WriteFlag GetWriteFlag() const;
+  bool IsMemoryAccess() const;
+};
 
 void MaybeReexec();
 
 template <typename Fn>
 class RunOnDestruction {
  public:
   explicit RunOnDestruction(Fn fn) : fn_(fn) {}
   ~RunOnDestruction() { fn_(); }

compiler-rt/lib/sanitizer_common/sanitizer_linux.cc

if (ctx->magic == kEsrMagic) {
       return true;
     }
     aux += ctx->size;
   }
   return false;
 }
 #endif
 
-SignalContext::WriteFlag SignalContext::GetWriteFlag(void *context) {
+SignalContext::WriteFlag SignalContext::GetWriteFlag() const {
   ucontext_t *ucontext = (ucontext_t *)context;
 #if defined(__x86_64__) || defined(__i386__)
   static const uptr PF_WRITE = 1U << 1;
 #if SANITIZER_FREEBSD
   uptr err = ucontext->uc_mcontext.mc_err;
 #elif SANITIZER_NETBSD
   uptr err = ucontext->uc_mcontext.__gregs[_REG_ERR];
 #else
#else
   return UNKNOWN;  // FIXME: Implement.
 #endif
 }
 
 void SignalContext::DumpAllRegisters(void *context) {
   // FIXME: Implement this.
 }
 
-void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
+static void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
 #if defined(__arm__)
   ucontext_t *ucontext = (ucontext_t*)context;
   *pc = ucontext->uc_mcontext.arm_pc;
   *bp = ucontext->uc_mcontext.arm_fp;
   *sp = ucontext->uc_mcontext.arm_sp;
 #elif defined(__aarch64__)
   ucontext_t *ucontext = (ucontext_t*)context;
   *pc = ucontext->uc_mcontext.pc;

 # endif
   *bp = ucontext->uc_mcontext.gregs[11];
   *sp = ucontext->uc_mcontext.gregs[15];
 #else
 # error "Unsupported arch"
 #endif
 }
 
+void SignalContext::InitPcSpBp() { GetPcSpBp(context, &pc, &sp, &bp); }
+
 void MaybeReexec() {
   // No need to re-exec on Linux.
 }
 
 void PrintModuleMap() { }
 
 void CheckNoDeepBind(const char *filename, int flag) {
 #ifdef RTLD_DEEPBIND

compiler-rt/lib/sanitizer_common/sanitizer_mac.cc

#endif
   BlockingMutexLock l(&syslog_lock);
   if (common_flags()->log_to_syslog)
     WriteToSyslog(buffer);
 
   // The report is added to CrashLog as part of logging all of Printf output.
 #endif
 }
 
-SignalContext::WriteFlag SignalContext::GetWriteFlag(void *context) {
+SignalContext::WriteFlag SignalContext::GetWriteFlag() const {
 #if defined(__x86_64__) || defined(__i386__)
   ucontext_t *ucontext = static_cast<ucontext_t*>(context);
   return ucontext->uc_mcontext->__es.__err & 2 /*T_PF_WRITE*/ ? WRITE : READ;
 #else
   return UNKNOWN;
 #endif
 }
 
-void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
+static void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
   ucontext_t *ucontext = (ucontext_t*)context;
 # if defined(__aarch64__)
   *pc = ucontext->uc_mcontext->__ss.__pc;
 #   if defined(__IPHONE_8_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_8_0
   *bp = ucontext->uc_mcontext->__ss.__fp;
 #   else
   *bp = ucontext->uc_mcontext->__ss.__lr;
 #   endif
# elif defined(__i386__)
   *pc = ucontext->uc_mcontext->__ss.__eip;
   *bp = ucontext->uc_mcontext->__ss.__ebp;
   *sp = ucontext->uc_mcontext->__ss.__esp;
 # else
 # error "Unknown architecture"
 # endif
 }
 
+void SignalContext::InitPcSpBp() { GetPcSpBp(context, &pc, &sp, &bp); }
+
 #if !SANITIZER_GO
 static const char kDyldInsertLibraries[] = "DYLD_INSERT_LIBRARIES";
 LowLevelAllocator allocator_for_env;
 
 // Change the value of the env var |name|, leaking the original value.
 // If |name_value| is NULL, the variable is deleted from the environment,
 // otherwise the corresponding "NAME=value" string is replaced with
 // |name_value|.

compiler-rt/lib/sanitizer_common/sanitizer_posix.cc

if (segment.IsExecutable() &&
       *start = segment.start;
       *end = segment.end;
       return true;
     }
   }
   return false;
 }
 
-SignalContext SignalContext::Create(void *siginfo, void *context) {
+uptr SignalContext::GetAddress() const {
   auto si = static_cast<const siginfo_t *>(siginfo);
-  uptr addr = (uptr)si->si_addr;
-  uptr pc, sp, bp;
-  GetPcSpBp(context, &pc, &sp, &bp);
-  WriteFlag write_flag = GetWriteFlag(context);
-  bool is_memory_access = si->si_signo == SIGSEGV;
-  return SignalContext(siginfo, context, addr, pc, sp, bp, is_memory_access,
-                       write_flag);
+  return (uptr)si->si_addr;
+}
+
+bool SignalContext::IsMemoryAccess() const {
+  auto si = static_cast<const siginfo_t *>(siginfo);
+  return si->si_signo == SIGSEGV;
 }
 
 int SignalContext::GetType() const {
   return static_cast<const siginfo_t *>(siginfo)->si_signo;
 }
 
 const char *SignalContext::Describe() const {
   switch (GetType()) {

compiler-rt/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc

static void TracerThreadDieCallback() {
   if (inst && stoptheworld_tracer_pid == internal_getpid()) {
     inst->KillAllThreads();
     thread_suspender_instance = nullptr;
   }
 }
 
 // Signal handler to wake up suspended threads when the tracer thread dies.
 static void TracerThreadSignalHandler(int signum, void *siginfo, void *uctx) {
-  SignalContext ctx = SignalContext::Create(siginfo, uctx);
+  SignalContext ctx(siginfo, uctx);
   Printf("Tracer caught signal %d: addr=0x%zx pc=0x%zx sp=0x%zx\n", signum,
          ctx.addr, ctx.pc, ctx.sp);
   ThreadSuspender *inst = thread_suspender_instance;
   if (inst) {
     if (signum == SIGABRT)
       inst->KillAllThreads();
     else
       inst->ResumeAllThreads();

compiler-rt/lib/sanitizer_common/sanitizer_win.cc

if (info.RegionSize == 0)
       return false;
 
     page += info.RegionSize;
   }
 
   return true;
 }
 
-SignalContext SignalContext::Create(void *siginfo, void *context) {
+void SignalContext::InitPcSpBp() {
   EXCEPTION_RECORD *exception_record = (EXCEPTION_RECORD *)siginfo;
   CONTEXT *context_record = (CONTEXT *)context;
 
-  uptr pc = (uptr)exception_record->ExceptionAddress;
+  pc = (uptr)exception_record->ExceptionAddress;
 #ifdef _WIN64
-  uptr bp = (uptr)context_record->Rbp;
-  uptr sp = (uptr)context_record->Rsp;
+  bp = (uptr)context_record->Rbp;
+  sp = (uptr)context_record->Rsp;
 #else
-  uptr bp = (uptr)context_record->Ebp;
-  uptr sp = (uptr)context_record->Esp;
+  bp = (uptr)context_record->Ebp;
+  sp = (uptr)context_record->Esp;
 #endif
-  uptr access_addr = exception_record->ExceptionInformation[1];
+}
+
+uptr SignalContext::GetAddress() const {
+  EXCEPTION_RECORD *exception_record = (EXCEPTION_RECORD *)siginfo;
+  return exception_record->ExceptionInformation[1];
+}
+
+bool SignalContext::IsMemoryAccess() const {
+  return GetWriteFlag() != SignalContext::UNKNOWN;
+}
 
+int SignalContext::GetType() const {
+  return static_cast<const siginfo_t *>(siginfo)->si_signo;
+}
+
+SignalContext::WriteFlag SignalContext::GetWriteFlag() const {
+  EXCEPTION_RECORD *exception_record = (EXCEPTION_RECORD *)siginfo;
   // The contents of this array are documented at
   // https://msdn.microsoft.com/en-us/library/windows/desktop/aa363082(v=vs.85).aspx
   // The first element indicates read as 0, write as 1, or execute as 8.  The
   // second element is the faulting address.
-  WriteFlag write_flag = SignalContext::UNKNOWN;
   switch (exception_record->ExceptionInformation[0]) {
-  case 0: write_flag = SignalContext::READ; break;
-  case 1: write_flag = SignalContext::WRITE; break;
-  case 8: write_flag = SignalContext::UNKNOWN; break;
-  }
-  bool is_memory_access = write_flag != SignalContext::UNKNOWN;
-  return SignalContext(siginfo, context, access_addr, pc, sp, bp,
-                       is_memory_access, write_flag);
+    case 0:
+      return SignalContext::READ;
+    case 1:
+      return SignalContext::WRITE;
+    case 8:
+      return SignalContext::UNKNOWN;
+  }
+  return SignalContext::UNKNOWN;
 }
 
 void SignalContext::DumpAllRegisters(void *context) {
   // FIXME: Implement this.
 }
 
 int SignalContext::GetType() const {
   return static_cast<const EXCEPTION_RECORD *>(siginfo)->ExceptionCode;