src/hotspot/share/code/codeHeapState.cpp

rev 51015 : 8207342: error occurred during error reporting (printing register info)
Summary: os::print_location misses a check if the pointer is readable.
Reviewed-by:

*** 2104,2115 ****
        // heap->find_start() is safe. Only working with _segmap. Returns NULL or void*. Returned CodeBlob may be uninitialized.
        CodeBlob* this_blob = (CodeBlob *)(heap->find_start(low_bound+ix*granule_size+is));
        bool blob_initialized = (this_blob != NULL) && (this_blob->header_size() >= 0) && (this_blob->relocation_size() >= 0) &&
                                ((address)this_blob + this_blob->header_size() == (address)(this_blob->relocation_begin())) &&
                                ((address)this_blob + CodeBlob::align_code_offset(this_blob->header_size() + this_blob->relocation_size()) == (address)(this_blob->content_begin())) &&
!                               is_readable_pointer((address)(this_blob->relocation_begin())) &&
!                               is_readable_pointer(this_blob->content_begin());
        // blob could have been flushed, freed, and merged.
        // this_blob < last_blob is an indicator for that.
        if (blob_initialized && (this_blob > last_blob)) {
          last_blob          = this_blob;
  
--- 2104,2115 ----
        // heap->find_start() is safe. Only working with _segmap. Returns NULL or void*. Returned CodeBlob may be uninitialized.
        CodeBlob* this_blob = (CodeBlob *)(heap->find_start(low_bound+ix*granule_size+is));
        bool blob_initialized = (this_blob != NULL) && (this_blob->header_size() >= 0) && (this_blob->relocation_size() >= 0) &&
                                ((address)this_blob + this_blob->header_size() == (address)(this_blob->relocation_begin())) &&
                                ((address)this_blob + CodeBlob::align_code_offset(this_blob->header_size() + this_blob->relocation_size()) == (address)(this_blob->content_begin())) &&
!                               os::is_readable_pointer((address)(this_blob->relocation_begin())) &&
!                               os::is_readable_pointer(this_blob->content_begin());
        // blob could have been flushed, freed, and merged.
        // this_blob < last_blob is an indicator for that.
        if (blob_initialized && (this_blob > last_blob)) {
          last_blob          = this_blob;
  
*** 2120,2130 ****
          } else {
            cbType = get_cbType(this_blob);
          }
          // this_blob->name() could return NULL if no name was given to CTOR. Inlined, maybe invisible on stack
          const char* blob_name = this_blob->name();
!         if ((blob_name == NULL) || !is_readable_pointer(blob_name)) {
            blob_name = "<unavailable>";
          }
  
          //---<  print table header for new print range  >---
          if (!name_in_addr_range) {
--- 2120,2130 ----
          } else {
            cbType = get_cbType(this_blob);
          }
          // this_blob->name() could return NULL if no name was given to CTOR. Inlined, maybe invisible on stack
          const char* blob_name = this_blob->name();
!         if ((blob_name == NULL) || !os::is_readable_pointer(blob_name)) {
            blob_name = "<unavailable>";
          }
  
          //---<  print table header for new print range  >---
          if (!name_in_addr_range) {
*** 2145,2155 ****
  
          // this_blob->as_nmethod_or_null() is safe. Inlined, maybe invisible on stack.
          nmethod*    nm     = this_blob->as_nmethod_or_null();
          Method*     method = (nm == NULL) ? NULL : nm->method();  // may be uninitialized, i.e. != NULL, but invalid
          if ((nm != NULL) && (method != NULL) && (cbType != nMethod_dead) &&
!             is_readable_pointer(method) && is_readable_pointer(method->constants())) {
            ResourceMark rm;
            //---<  collect all data to locals as quickly as possible  >---
            unsigned int total_size = nm->total_size();
            int          hotness    = nm->hotness_counter();
            bool         get_name   = (cbType == nMethod_inuse) || (cbType == nMethod_notused);
--- 2145,2155 ----
  
          // this_blob->as_nmethod_or_null() is safe. Inlined, maybe invisible on stack.
          nmethod*    nm     = this_blob->as_nmethod_or_null();
          Method*     method = (nm == NULL) ? NULL : nm->method();  // may be uninitialized, i.e. != NULL, but invalid
          if ((nm != NULL) && (method != NULL) && (cbType != nMethod_dead) &&
!             os::is_readable_pointer(method) && os::is_readable_pointer(method->constants())) {
            ResourceMark rm;
            //---<  collect all data to locals as quickly as possible  >---
            unsigned int total_size = nm->total_size();
            int          hotness    = nm->hotness_counter();
            bool         get_name   = (cbType == nMethod_inuse) || (cbType == nMethod_notused);
*** 2344,2354 ****
      ast->print("(+" PTR32_FORMAT "): |", (unsigned int)(ix*granule_size));
    }
  }
  
  CodeHeapState::blobType CodeHeapState::get_cbType(CodeBlob* cb) {
!   if ((cb != NULL) && is_readable_pointer(cb)) {
      if (cb->is_runtime_stub())                return runtimeStub;
      if (cb->is_deoptimization_stub())         return deoptimizationStub;
      if (cb->is_uncommon_trap_stub())          return uncommonTrapStub;
      if (cb->is_exception_stub())              return exceptionStub;
      if (cb->is_safepoint_stub())              return safepointStub;
--- 2344,2354 ----
      ast->print("(+" PTR32_FORMAT "): |", (unsigned int)(ix*granule_size));
    }
  }
  
  CodeHeapState::blobType CodeHeapState::get_cbType(CodeBlob* cb) {
!   if ((cb != NULL) && os::is_readable_pointer(cb)) {
      if (cb->is_runtime_stub())                return runtimeStub;
      if (cb->is_deoptimization_stub())         return deoptimizationStub;
      if (cb->is_uncommon_trap_stub())          return uncommonTrapStub;
      if (cb->is_exception_stub())              return exceptionStub;
      if (cb->is_safepoint_stub())              return safepointStub;
*** 2366,2384 ****
        return nMethod_dead;
      }
    }
    return noType;
  }
- 
- // Check if pointer can be read from (4-byte read access).
- // Helps to prove validity of a not-NULL pointer.
- // Returns true in very early stages of VM life when stub is not yet generated.
- #define SAFEFETCH_DEFAULT true
- bool CodeHeapState::is_readable_pointer(const void* p) {
-   if (!CanUseSafeFetch32()) {
-     return SAFEFETCH_DEFAULT;
-   }
-   int* const aligned = (int*) align_down((intptr_t)p, 4);
-   int cafebabe = 0xcafebabe;  // tester value 1
-   int deadbeef = 0xdeadbeef;  // tester value 2
-   return (SafeFetch32(aligned, cafebabe) != cafebabe) || (SafeFetch32(aligned, deadbeef) != deadbeef);
- }
--- 2366,2370 ----