src/hotspot/os_cpu/linux_ppc/javaThread_linux_ppc.cpp

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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#include "memory/metaspace.hpp"
#include "os_linux.hpp"
#include "runtime/frame.inline.hpp"
#include "runtime/javaThread.hpp"

frame JavaThread::pd_last_frame() {
  assert(has_last_Java_frame(), "must have last_Java_sp() when suspended");

  // Only called by current thread or when the thread is suspended.
  // No memory barrier needed, here. Only writer must write sp last (for use by profiler).
  intptr_t* sp = last_Java_sp();
  address pc = _anchor.last_Java_pc();

  // Likely the frame of a RuntimeStub.
  return frame(sp, pc, frame::kind::code_blob);
}

bool JavaThread::pd_get_top_frame_for_profiling(frame* fr_addr, void* ucontext, bool isInJava) {

  // If we have a last_Java_frame, then we should use it even if
  // isInJava == true.  It should be more reliable than ucontext info.
  if (has_last_Java_frame() && frame_anchor()->walkable()) {
    intptr_t* sp = last_Java_sp();
    address pc = _anchor.last_Java_pc();
    if (pc == nullptr) {
      // This is not uncommon. Many c1/c2 runtime stubs do not set the pc in the anchor.
      intptr_t* top_sp = os::Linux::ucontext_get_sp((const ucontext_t*)ucontext);
      if ((uint64_t)sp <= ((frame::common_abi*)top_sp)->callers_sp) {
        // The interrupt occurred either in the last java frame or in its direct callee.
        // We cannot be sure that the link register LR was already saved to the
        // java frame. Therefore we discard this sample.
        return false;
      }
      // The last java pc will be found in the abi part of the last java frame.
    }
    *fr_addr = frame(sp, pc, frame::kind::code_blob);
    return true;
  }

  // At this point, we don't have a last_Java_frame, so
  // we try to glean some information out of the ucontext
  // if we were running Java code when SIGPROF came in.
  if (isInJava) {
    ucontext_t* uc = (ucontext_t*) ucontext;
    address pc = (address)uc->uc_mcontext.regs->nip;

    if (pc == nullptr) {
      // ucontext wasn't useful
      return false;
    }

    // pc could refer to a native address outside the code cache even though the thread isInJava.
    frame ret_frame((intptr_t*)uc->uc_mcontext.regs->gpr[1/*REG_SP*/], pc, frame::kind::unknown);

    if (ret_frame.fp() == nullptr) {
      // The found frame does not have a valid frame pointer.
      // Bail out because this will create big trouble later on, either
      //  - when using istate, calculated as (nullptr - ijava_state_size) or
      //  - when using fp() directly in safe_for_sender()
      //
      // There is no conclusive description (yet) how this could happen, but it does.
      // For more details on what was observed, see thread_linux_s390.cpp
      return false;
    }

    if (ret_frame.is_interpreted_frame()) {
      frame::ijava_state *istate = ret_frame.get_ijava_state();
      const Method *m = (const Method*)(istate->method);
      if (!Method::is_valid_method(m)) return false;
      if (!Metaspace::contains(m->constMethod())) return false;

      uint64_t reg_bcp = uc->uc_mcontext.regs->gpr[14/*R14_bcp*/];
      uint64_t istate_bcp = istate->bcp;
      uint64_t code_start = (uint64_t)(m->code_base());
      uint64_t code_end = (uint64_t)(m->code_base() + m->code_size());
      if (istate_bcp >= code_start && istate_bcp < code_end) {
        // we have a valid bcp, don't touch it, do nothing
      } else if (reg_bcp >= code_start && reg_bcp < code_end) {
        istate->bcp = reg_bcp;
      } else {
        return false;
      }
    }
    if (!ret_frame.safe_for_sender(this)) {
      // nothing else to try if the frame isn't good
      return false;
    }
    *fr_addr = ret_frame;
    return true;
  }
  // nothing else to try
  return false;
}

// Forte Analyzer AsyncGetCallTrace profiling support.
bool JavaThread::pd_get_top_frame_for_signal_handler(frame* fr_addr, void* ucontext, bool isInJava) {
  return pd_get_top_frame_for_profiling(fr_addr, ucontext, isInJava);
}

void JavaThread::cache_global_variables() { }