jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2021, Patrick Meyer <git@the-space.agency>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <Kernel/Devices/KCOVInstance.h>
8
9namespace Kernel {
10
11KCOVInstance::KCOVInstance(ProcessID pid)
12{
13 m_pid = pid;
14}
15
16ErrorOr<void> KCOVInstance::buffer_allocate(size_t buffer_size_in_entries)
17{
18 if (buffer_size_in_entries < 2 || buffer_size_in_entries > KCOV_MAX_ENTRIES)
19 return EINVAL;
20
21 // first entry contains index of last PC
22 m_buffer_size_in_entries = buffer_size_in_entries - 1;
23 m_buffer_size_in_bytes = TRY(Memory::page_round_up(buffer_size_in_entries * KCOV_ENTRY_SIZE));
24
25 // one single vmobject is representing the buffer
26 // - we allocate one kernel region using that vmobject
27 // - when an mmap call comes in, we allocate another userspace region,
28 // backed by the same vmobject
29 m_vmobject = TRY(Memory::AnonymousVMObject::try_create_with_size(m_buffer_size_in_bytes, AllocationStrategy::AllocateNow));
30
31 auto region_name = TRY(KString::formatted("kcov_{}", m_pid));
32 m_kernel_region = TRY(MM.allocate_kernel_region_with_vmobject(
33 *m_vmobject, m_buffer_size_in_bytes, region_name->view(),
34 Memory::Region::Access::ReadWrite));
35
36 m_buffer = (u64*)m_kernel_region->vaddr().as_ptr();
37 return {};
38}
39
40void KCOVInstance::buffer_add_pc(u64 pc)
41{
42 auto idx = (u64)m_buffer[0];
43 if (idx >= m_buffer_size_in_entries) {
44 // the buffer is already full
45 return;
46 }
47
48 m_buffer[idx + 1] = pc;
49 m_buffer[0] = idx + 1;
50}
51
52}