text: /*
   * Copyright (c) 2021, Patrick Meyer <git@the-space.agency>
   *
   * SPDX-License-Identifier: BSD-2-Clause
   */
  
  #include <Kernel/Devices/KCOVInstance.h>
  
  namespace Kernel {
  
  KCOVInstance::KCOVInstance(ProcessID pid)
  {
      m_pid = pid;
  }
  
  ErrorOr<void> KCOVInstance::buffer_allocate(size_t buffer_size_in_entries)
  {
      if (buffer_size_in_entries < 2 || buffer_size_in_entries > KCOV_MAX_ENTRIES)
          return EINVAL;
  
      // first entry contains index of last PC
      m_buffer_size_in_entries = buffer_size_in_entries - 1;
      m_buffer_size_in_bytes = TRY(Memory::page_round_up(buffer_size_in_entries * KCOV_ENTRY_SIZE));
  
      // one single vmobject is representing the buffer
      // - we allocate one kernel region using that vmobject
      // - when an mmap call comes in, we allocate another userspace region,
      //   backed by the same vmobject
      m_vmobject = TRY(Memory::AnonymousVMObject::try_create_with_size(m_buffer_size_in_bytes, AllocationStrategy::AllocateNow));
  
      auto region_name = TRY(KString::formatted("kcov_{}", m_pid));
      m_kernel_region = TRY(MM.allocate_kernel_region_with_vmobject(
          *m_vmobject, m_buffer_size_in_bytes, region_name->view(),
          Memory::Region::Access::ReadWrite));
  
      m_buffer = (u64*)m_kernel_region->vaddr().as_ptr();
      return {};
  }
  
  void KCOVInstance::buffer_add_pc(u64 pc)
  {
      auto idx = (u64)m_buffer[0];
      if (idx >= m_buffer_size_in_entries) {
          // the buffer is already full
          return;
      }
  
      m_buffer[idx + 1] = pc;
      m_buffer[0] = idx + 1;
  }
  
  }
  