src/hotspot/cpu/arm/frame_arm.cpp

/*
 * Copyright (c) 2008, 2021, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "precompiled.hpp"
#include "compiler/oopMap.hpp"
#include "interpreter/interpreter.hpp"
#include "memory/resourceArea.hpp"
#include "memory/universe.hpp"
#include "oops/markWord.hpp"
#include "oops/method.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/frame.inline.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/monitorChunk.hpp"
#include "runtime/os.inline.hpp"
#include "runtime/signature.hpp"
#include "runtime/stubCodeGenerator.hpp"
#include "runtime/stubRoutines.hpp"
#include "vmreg_arm.inline.hpp"
#ifdef COMPILER1
#include "c1/c1_Runtime1.hpp"
#include "runtime/vframeArray.hpp"
#endif
#include "prims/methodHandles.hpp"

#ifdef ASSERT
void RegisterMap::check_location_valid() {
}
#endif


// Profiling/safepoint support

bool frame::safe_for_sender(JavaThread *thread) {
  address   sp = (address)_sp;
  address   fp = (address)_fp;
  address   unextended_sp = (address)_unextended_sp;

  // consider stack guards when trying to determine "safe" stack pointers
  // sp must be within the usable part of the stack (not in guards)
  if (!thread->is_in_usable_stack(sp)) {
    return false;
  }

  if (!thread->is_in_stack_range_incl(unextended_sp, sp)) {
    return false;
  }

  // We know sp/unextended_sp are safe. Only fp is questionable here.

  bool fp_safe = thread->is_in_stack_range_incl(fp, sp);

  if (_cb != NULL ) {

    // First check if frame is complete and tester is reliable
    // Unfortunately we can only check frame complete for runtime stubs and nmethod
    // other generic buffer blobs are more problematic so we just assume they are
    // ok. adapter blobs never have a frame complete and are never ok.

    if (!_cb->is_frame_complete_at(_pc)) {
      if (_cb->is_compiled() || _cb->is_adapter_blob() || _cb->is_runtime_stub()) {
        return false;
      }
    }

    // Could just be some random pointer within the codeBlob
    if (!_cb->code_contains(_pc)) {
      return false;
    }

    // Entry frame checks
    if (is_entry_frame()) {
      // an entry frame must have a valid fp.
      return fp_safe && is_entry_frame_valid(thread);
    }

    intptr_t* sender_sp = NULL;
    address   sender_pc = NULL;

    if (is_interpreted_frame()) {
      // fp must be safe
      if (!fp_safe) {
        return false;
      }

      sender_pc = (address) this->fp()[return_addr_offset];
      sender_sp = (intptr_t*) addr_at(sender_sp_offset);

    } else {
      // must be some sort of compiled/runtime frame
      // fp does not have to be safe (although it could be check for c1?)

      sender_sp = _unextended_sp + _cb->frame_size();
      // Is sender_sp safe?
      if (!thread->is_in_full_stack_checked((address)sender_sp)) {
        return false;
      }
      // With our calling conventions, the return_address should
      // end up being the word on the stack
      sender_pc = (address) *(sender_sp - sender_sp_offset + return_addr_offset);
    }

    // We must always be able to find a recognizable pc
    CodeBlob* sender_blob = CodeCache::find_blob_unsafe(sender_pc);
    if (sender_pc == NULL || sender_blob == NULL) {
      return false;
    }


    // If the potential sender is the interpreter then we can do some more checking
    if (Interpreter::contains(sender_pc)) {

      // FP is always saved in a recognizable place in any code we generate. However
      // only if the sender is interpreted/call_stub (c1 too?) are we certain that the saved FP
      // is really a frame pointer.

      intptr_t *saved_fp = (intptr_t*)*(sender_sp - frame::sender_sp_offset + link_offset);
      if (!thread->is_in_stack_range_excl((address)saved_fp, (address)sender_sp)) {
        return false;
      }

      // construct the potential sender

      frame sender(sender_sp, saved_fp, sender_pc);

      return sender.is_interpreted_frame_valid(thread);
    }

    if (sender_blob->is_zombie() || sender_blob->is_unloaded()) {
      return false;
    }

    // Could just be some random pointer within the codeBlob
    if (!sender_blob->code_contains(sender_pc)) {
      return false;
    }

    // We should never be able to see an adapter if the current frame is something from code cache
    if (sender_blob->is_adapter_blob()) {
      return false;
    }

    // Could be the call_stub
    if (StubRoutines::returns_to_call_stub(sender_pc)) {
      intptr_t *saved_fp = (intptr_t*)*(sender_sp - frame::sender_sp_offset + link_offset);
      if (!thread->is_in_stack_range_excl((address)saved_fp, (address)sender_sp)) {
        return false;
      }

      // construct the potential sender

      frame sender(sender_sp, saved_fp, sender_pc);

      // Validate the JavaCallWrapper an entry frame must have
      address jcw = (address)sender.entry_frame_call_wrapper();

      return thread->is_in_stack_range_excl(jcw, (address)sender.fp());
    }

    // If the frame size is 0 something (or less) is bad because every nmethod has a non-zero frame size
    // because the return address counts against the callee's frame.

    if (sender_blob->frame_size() <= 0) {
      assert(!sender_blob->is_compiled(), "should count return address at least");
      return false;
    }

    // We should never be able to see anything here except an nmethod. If something in the
    // code cache (current frame) is called by an entity within the code cache that entity
    // should not be anything but the call stub (already covered), the interpreter (already covered)
    // or an nmethod.

    if (!sender_blob->is_compiled()) {
      return false;
    }

    // Could put some more validation for the potential non-interpreted sender
    // frame we'd create by calling sender if I could think of any. Wait for next crash in forte...

    // One idea is seeing if the sender_pc we have is one that we'd expect to call to current cb

    // We've validated the potential sender that would be created
    return true;
  }

  // Must be native-compiled frame. Since sender will try and use fp to find
  // linkages it must be safe

  if (!fp_safe) {
    return false;
  }

  // Will the pc we fetch be non-zero (which we'll find at the oldest frame)

  if ((address) this->fp()[return_addr_offset] == NULL) return false;


  // could try and do some more potential verification of native frame if we could think of some...

  return true;
}


void frame::patch_pc(Thread* thread, address pc) {
  assert(_cb == CodeCache::find_blob(pc), "unexpected pc");
  address* pc_addr = &((address *)sp())[-sender_sp_offset+return_addr_offset];
  if (TracePcPatching) {
    tty->print_cr("patch_pc at address" INTPTR_FORMAT " [" INTPTR_FORMAT " -> " INTPTR_FORMAT "] ",
                  p2i(pc_addr), p2i(*pc_addr), p2i(pc));
  }
  *pc_addr = pc;
  address original_pc = CompiledMethod::get_deopt_original_pc(this);
  if (original_pc != NULL) {
    assert(original_pc == _pc, "expected original PC to be stored before patching");
    _deopt_state = is_deoptimized;
    // leave _pc as is
  } else {
    _deopt_state = not_deoptimized;
    _pc = pc;
  }
}

bool frame::is_interpreted_frame() const  {
  return Interpreter::contains(pc());
}

int frame::frame_size(RegisterMap* map) const {
  frame sender = this->sender(map);
  return sender.sp() - sp();
}

intptr_t* frame::entry_frame_argument_at(int offset) const {
  assert(is_entry_frame(), "entry frame expected");
  // convert offset to index to deal with tsi
  int index = (Interpreter::expr_offset_in_bytes(offset)/wordSize);
  // Entry frame's arguments are always in relation to unextended_sp()
  return &unextended_sp()[index];
}

// sender_sp
intptr_t* frame::interpreter_frame_sender_sp() const {
  assert(is_interpreted_frame(), "interpreted frame expected");
  return (intptr_t*) at(interpreter_frame_sender_sp_offset);
}

void frame::set_interpreter_frame_sender_sp(intptr_t* sender_sp) {
  assert(is_interpreted_frame(), "interpreted frame expected");
  ptr_at_put(interpreter_frame_sender_sp_offset, (intptr_t) sender_sp);
}


// monitor elements

BasicObjectLock* frame::interpreter_frame_monitor_begin() const {
  return (BasicObjectLock*) addr_at(interpreter_frame_monitor_block_bottom_offset);
}

BasicObjectLock* frame::interpreter_frame_monitor_end() const {
  BasicObjectLock* result = (BasicObjectLock*) *addr_at(interpreter_frame_monitor_block_top_offset);
  // make sure the pointer points inside the frame
  assert((intptr_t) fp() >  (intptr_t) result, "result must <  than frame pointer");
  assert((intptr_t) sp() <= (intptr_t) result, "result must >= than stack pointer");
  return result;
}

void frame::interpreter_frame_set_monitor_end(BasicObjectLock* value) {
  *((BasicObjectLock**)addr_at(interpreter_frame_monitor_block_top_offset)) = value;
}


// Used by template based interpreter deoptimization
void frame::interpreter_frame_set_last_sp(intptr_t* sp) {
    *((intptr_t**)addr_at(interpreter_frame_last_sp_offset)) = sp;
}


frame frame::sender_for_entry_frame(RegisterMap* map) const {
  assert(map != NULL, "map must be set");
  // Java frame called from C; skip all C frames and return top C
  // frame of that chunk as the sender
  JavaFrameAnchor* jfa = entry_frame_call_wrapper()->anchor();
  assert(!entry_frame_is_first(), "next Java fp must be non zero");
  assert(jfa->last_Java_sp() > sp(), "must be above this frame on stack");
  map->clear();
  assert(map->include_argument_oops(), "should be set by clear");
  if (jfa->last_Java_pc() != NULL) {
    frame fr(jfa->last_Java_sp(), jfa->last_Java_fp(), jfa->last_Java_pc());
    return fr;
  }
  frame fr(jfa->last_Java_sp(), jfa->last_Java_fp());
  return fr;
}

OptimizedEntryBlob::FrameData* OptimizedEntryBlob::frame_data_for_frame(const frame& frame) const {
  ShouldNotCallThis();
  return nullptr;
}

bool frame::optimized_entry_frame_is_first() const {
  ShouldNotCallThis();
  return false;
}

//------------------------------------------------------------------------------
// frame::verify_deopt_original_pc
//
// Verifies the calculated original PC of a deoptimization PC for the
// given unextended SP.  The unextended SP might also be the saved SP
// for MethodHandle call sites.
#ifdef ASSERT
void frame::verify_deopt_original_pc(CompiledMethod* nm, intptr_t* unextended_sp, bool is_method_handle_return) {
  frame fr;

  // This is ugly but it's better than to change {get,set}_original_pc
  // to take an SP value as argument.  And it's only a debugging
  // method anyway.
  fr._unextended_sp = unextended_sp;

  address original_pc = nm->get_original_pc(&fr);
  assert(nm->insts_contains_inclusive(original_pc),
         "original PC must be in the main code section of the the compiled method (or must be immediately following it)");
  assert(nm->is_method_handle_return(original_pc) == is_method_handle_return, "must be");
}
#endif

//------------------------------------------------------------------------------
// frame::adjust_unextended_sp
void frame::adjust_unextended_sp() {
  // same as on x86

  // If we are returning to a compiled MethodHandle call site, the
  // saved_fp will in fact be a saved value of the unextended SP.  The
  // simplest way to tell whether we are returning to such a call site
  // is as follows:

  CompiledMethod* sender_cm = (_cb == NULL) ? NULL : _cb->as_compiled_method_or_null();
  if (sender_cm != NULL) {
    // If the sender PC is a deoptimization point, get the original
    // PC.  For MethodHandle call site the unextended_sp is stored in
    // saved_fp.
    if (sender_cm->is_deopt_mh_entry(_pc)) {
      DEBUG_ONLY(verify_deopt_mh_original_pc(sender_cm, _fp));
      _unextended_sp = _fp;
    }
    else if (sender_cm->is_deopt_entry(_pc)) {
      DEBUG_ONLY(verify_deopt_original_pc(sender_cm, _unextended_sp));
    }
    else if (sender_cm->is_method_handle_return(_pc)) {
      _unextended_sp = _fp;
    }
  }
}

//------------------------------------------------------------------------------
// frame::update_map_with_saved_link
void frame::update_map_with_saved_link(RegisterMap* map, intptr_t** link_addr) {
  // see x86 for comments
  map->set_location(FP->as_VMReg(), (address) link_addr);
}

frame frame::sender_for_interpreter_frame(RegisterMap* map) const {
  // SP is the raw SP from the sender after adapter or interpreter
  // extension.
  intptr_t* sender_sp = this->sender_sp();

  // This is the sp before any possible extension (adapter/locals).
  intptr_t* unextended_sp = interpreter_frame_sender_sp();

#ifdef COMPILER2
  if (map->update_map()) {
    update_map_with_saved_link(map, (intptr_t**) addr_at(link_offset));
  }
#endif // COMPILER2

  return frame(sender_sp, unextended_sp, link(), sender_pc());
}

frame frame::sender_for_compiled_frame(RegisterMap* map) const {
  assert(map != NULL, "map must be set");

  // frame owned by optimizing compiler
  assert(_cb->frame_size() >= 0, "must have non-zero frame size");
  intptr_t* sender_sp = unextended_sp() + _cb->frame_size();
  intptr_t* unextended_sp = sender_sp;

  address sender_pc = (address) *(sender_sp - sender_sp_offset + return_addr_offset);

  // This is the saved value of FP which may or may not really be an FP.
  // It is only an FP if the sender is an interpreter frame (or C1?).
  intptr_t** saved_fp_addr = (intptr_t**) (sender_sp - sender_sp_offset + link_offset);

  if (map->update_map()) {
    // Tell GC to use argument oopmaps for some runtime stubs that need it.
    // For C1, the runtime stub might not have oop maps, so set this flag
    // outside of update_register_map.
    map->set_include_argument_oops(_cb->caller_must_gc_arguments(map->thread()));
    if (_cb->oop_maps() != NULL) {
      OopMapSet::update_register_map(this, map);
    }

    // Since the prolog does the save and restore of FP there is no oopmap
    // for it so we must fill in its location as if there was an oopmap entry
    // since if our caller was compiled code there could be live jvm state in it.
    update_map_with_saved_link(map, saved_fp_addr);
  }

  assert(sender_sp != sp(), "must have changed");
  return frame(sender_sp, unextended_sp, *saved_fp_addr, sender_pc);
}

frame frame::sender(RegisterMap* map) const {
  // Default is we done have to follow them. The sender_for_xxx will
  // update it accordingly
  map->set_include_argument_oops(false);

  if (is_entry_frame())       return sender_for_entry_frame(map);
  if (is_interpreted_frame()) return sender_for_interpreter_frame(map);
  assert(_cb == CodeCache::find_blob(pc()),"Must be the same");

  if (_cb != NULL) {
    return sender_for_compiled_frame(map);
  }

  assert(false, "should not be called for a C frame");
  return frame();
}

bool frame::is_interpreted_frame_valid(JavaThread* thread) const {
  assert(is_interpreted_frame(), "Not an interpreted frame");
  // These are reasonable sanity checks
  if (fp() == 0 || (intptr_t(fp()) & (wordSize-1)) != 0) {
    return false;
  }
  if (sp() == 0 || (intptr_t(sp()) & (wordSize-1)) != 0) {
    return false;
  }
  if (fp() + interpreter_frame_initial_sp_offset < sp()) {
    return false;
  }
  // These are hacks to keep us out of trouble.
  // The problem with these is that they mask other problems
  if (fp() <= sp()) {        // this attempts to deal with unsigned comparison above
    return false;
  }
  // do some validation of frame elements

  // first the method

  Method* m = *interpreter_frame_method_addr();

  // validate the method we'd find in this potential sender
  if (!Method::is_valid_method(m)) return false;

  // stack frames shouldn't be much larger than max_stack elements

  if (fp() - sp() > 1024 + m->max_stack()*Interpreter::stackElementSize) {
    return false;
  }

  // validate bci/bcp

  address bcp = interpreter_frame_bcp();
  if (m->validate_bci_from_bcp(bcp) < 0) {
    return false;
  }

  // validate ConstantPoolCache*
  ConstantPoolCache* cp = *interpreter_frame_cache_addr();
  if (MetaspaceObj::is_valid(cp) == false) return false;

  // validate locals

  address locals =  (address) *interpreter_frame_locals_addr();
  return thread->is_in_stack_range_incl(locals, (address)fp());
}

BasicType frame::interpreter_frame_result(oop* oop_result, jvalue* value_result) {
  assert(is_interpreted_frame(), "interpreted frame expected");
  Method* method = interpreter_frame_method();
  BasicType type = method->result_type();

  intptr_t* res_addr;
  if (method->is_native()) {
    // Prior to calling into the runtime to report the method_exit both of
    // the possible return value registers are saved.
    // Return value registers are pushed to the native stack
    res_addr = (intptr_t*)sp();
#ifdef __ABI_HARD__
    // FP result is pushed onto a stack along with integer result registers
    if (type == T_FLOAT || type == T_DOUBLE) {
      res_addr += 2;
    }
#endif // __ABI_HARD__
  } else {
    res_addr = (intptr_t*)interpreter_frame_tos_address();
  }

  switch (type) {
    case T_OBJECT  :
    case T_ARRAY   : {
      oop obj;
      if (method->is_native()) {
        obj = cast_to_oop(at(interpreter_frame_oop_temp_offset));
      } else {
        obj = *(oop*)res_addr;
      }
      assert(Universe::is_in_heap_or_null(obj), "sanity check");
      *oop_result = obj;
      break;
    }
    case T_BOOLEAN : value_result->z = *(jboolean*)res_addr; break;
    case T_BYTE    : value_result->b = *(jbyte*)res_addr; break;
    case T_CHAR    : value_result->c = *(jchar*)res_addr; break;
    case T_SHORT   : value_result->s = *(jshort*)res_addr; break;
    case T_INT     : value_result->i = *(jint*)res_addr; break;
    case T_LONG    : value_result->j = *(jlong*)res_addr; break;
    case T_FLOAT   : value_result->f = *(jfloat*)res_addr; break;
    case T_DOUBLE  : value_result->d = *(jdouble*)res_addr; break;
    case T_VOID    : /* Nothing to do */ break;
    default        : ShouldNotReachHere();
  }

  return type;
}


intptr_t* frame::interpreter_frame_tos_at(jint offset) const {
  int index = (Interpreter::expr_offset_in_bytes(offset)/wordSize);
  return &interpreter_frame_tos_address()[index];
}

#ifndef PRODUCT

#define DESCRIBE_FP_OFFSET(name) \
  values.describe(frame_no, fp() + frame::name##_offset, #name)

void frame::describe_pd(FrameValues& values, int frame_no) {
  if (is_interpreted_frame()) {
    DESCRIBE_FP_OFFSET(interpreter_frame_sender_sp);
    DESCRIBE_FP_OFFSET(interpreter_frame_last_sp);
    DESCRIBE_FP_OFFSET(interpreter_frame_method);
    DESCRIBE_FP_OFFSET(interpreter_frame_mdp);
    DESCRIBE_FP_OFFSET(interpreter_frame_cache);
    DESCRIBE_FP_OFFSET(interpreter_frame_locals);
    DESCRIBE_FP_OFFSET(interpreter_frame_bcp);
    DESCRIBE_FP_OFFSET(interpreter_frame_initial_sp);
  }
}

// This is a generic constructor which is only used by pns() in debug.cpp.
frame::frame(void* sp, void* fp, void* pc) {
  init((intptr_t*)sp, (intptr_t*)fp, (address)pc);
}

void frame::pd_ps() {}
#endif

intptr_t *frame::initial_deoptimization_info() {
  // used to reset the saved FP
  return fp();
}

intptr_t* frame::real_fp() const {
  if (is_entry_frame()) {
    // Work-around: FP (currently) does not conform to the ABI for entry
    // frames (see generate_call_stub). Might be worth fixing as another CR.
    // Following code assumes (and asserts) this has not yet been fixed.
    assert(frame::entry_frame_call_wrapper_offset == 0, "adjust this code");
    intptr_t* new_fp = fp();
    new_fp += 5; // saved R0,R1,R2,R4,R10
#ifndef __SOFTFP__
    new_fp += 8*2; // saved D8..D15
#endif
    return new_fp;
  }
  if (_cb != NULL) {
    // use the frame size if valid
    int size = _cb->frame_size();
    if (size > 0) {
      return unextended_sp() + size;
    }
  }
  // else rely on fp()
  assert(! is_compiled_frame(), "unknown compiled frame size");
  return fp();
}