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      1 //===-- hwasan_exceptions.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 // This file is a part of HWAddressSanitizer.
     10 //
     11 // HWAddressSanitizer runtime.
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "hwasan_poisoning.h"
     15 #include "sanitizer_common/sanitizer_common.h"
     16 
     17 #include <unwind.h>
     18 
     19 using namespace __hwasan;
     20 using namespace __sanitizer;
     21 
     22 typedef _Unwind_Reason_Code PersonalityFn(int version, _Unwind_Action actions,
     23                                           uint64_t exception_class,
     24                                           _Unwind_Exception* unwind_exception,
     25                                           _Unwind_Context* context);
     26 
     27 // Pointers to the _Unwind_GetGR and _Unwind_GetCFA functions are passed in
     28 // instead of being called directly. This is to handle cases where the unwinder
     29 // is statically linked and the sanitizer runtime and the program are linked
     30 // against different unwinders. The _Unwind_Context data structure is opaque so
     31 // it may be incompatible between unwinders.
     32 typedef uintptr_t GetGRFn(_Unwind_Context* context, int index);
     33 typedef uintptr_t GetCFAFn(_Unwind_Context* context);
     34 
     35 extern "C" SANITIZER_INTERFACE_ATTRIBUTE _Unwind_Reason_Code
     36 __hwasan_personality_wrapper(int version, _Unwind_Action actions,
     37                              uint64_t exception_class,
     38                              _Unwind_Exception* unwind_exception,
     39                              _Unwind_Context* context,
     40                              PersonalityFn* real_personality, GetGRFn* get_gr,
     41                              GetCFAFn* get_cfa) {
     42   _Unwind_Reason_Code rc;
     43   if (real_personality)
     44     rc = real_personality(version, actions, exception_class, unwind_exception,
     45                           context);
     46   else
     47     rc = _URC_CONTINUE_UNWIND;
     48 
     49   // We only untag frames without a landing pad because landing pads are
     50   // responsible for untagging the stack themselves if they resume.
     51   //
     52   // Here we assume that the frame record appears after any locals. This is not
     53   // required by AAPCS but is a requirement for HWASAN instrumented functions.
     54   if ((actions & _UA_CLEANUP_PHASE) && rc == _URC_CONTINUE_UNWIND) {
     55 #if defined(__x86_64__)
     56     uptr fp = get_gr(context, 6); // rbp
     57 #elif defined(__aarch64__)
     58     uptr fp = get_gr(context, 29); // x29
     59 #elif SANITIZER_RISCV64
     60     uptr fp = get_gr(context, 8);  // x8
     61 #else
     62 #error Unsupported architecture
     63 #endif
     64     uptr sp = get_cfa(context);
     65     TagMemory(UntagAddr(sp), UntagAddr(fp) - UntagAddr(sp),
     66               GetTagFromPointer(sp));
     67   }
     68 
     69   return rc;
     70 }
     71