[Lldb-commits] [PATCH] D71372: [lldb] Add additional validation on return address in 'thread step-out'

[Ted Woodward via Phabricator via lldb-commits]

ted added a comment.

I've got another failure case for this. If the remote gdbserver doesn't implement qMemoryRegionInfo or qXfer:memory-map:read, thread step-out will fail.

error: Could not create return address breakpoint. Return address (0x5bc0) permissions not found.

That comes from this code:

  if (!m_thread.GetProcess()->GetLoadAddressPermissions(m_return_addr,
                                                        permissions)) {
    m_constructor_errors.Printf("Return address (0x%" PRIx64
                                ") permissions not found.",
                                m_return_addr);
    LLDB_LOGF(log, "ThreadPlanStepOut(%p): %s", static_cast<void *>(this),
              m_constructor_errors.GetData());
    return;

GetLoadAddressPermissions does this:

  Status error(GetMemoryRegionInfo(load_addr, range_info));
  if (!error.Success())
    return false;

and ProcessGDBRemote::GetMemoryRegionInfo will send a qMemoryRegionInfo. If that fails, it will try qXfer::memory-map:read. qMemoryRegionInfo isn't required:

//----------------------------------------------------------------------
// "qMemoryRegionInfo:<addr>"
//
// BRIEF
//  Get information about the address range that contains "<addr>"
//
// PRIORITY TO IMPLEMENT
//  Medium. This is nice to have, but it isn't necessary.

Many embedded stubs do not implement this, which means thread step-out won't work with them anymore.

How should we fix this?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71372/new/

https://reviews.llvm.org/D71372