mirror of
https://github.com/SerenityOS/serenity
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a721e4d507
While this clutters Process.cpp a tiny bit, I feel that it's worth it: - 2x speed on the kcov_loop benchmark. Likely more during fuzzing. - Overall code complexity is going down with this change. - By reducing the code reachable from __sanitizer_cov_trace_pc code, we can now instrument more code.
57 lines
1.8 KiB
C++
57 lines
1.8 KiB
C++
/*
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* Copyright (c) 2021, Patrick Meyer <git@the-space.agency>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <Kernel/API/kcov.h>
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#include <Kernel/Locking/Spinlock.h>
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#include <Kernel/Memory/AnonymousVMObject.h>
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namespace Kernel {
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#define KCOV_MAX_ENTRIES (10 * 1024 * 1024)
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/*
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* 1. When a thread opens /dev/kcov for the first time, a KCOVInstance is
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* allocated and tracked via an OwnPtr on the Kernel::Process object.
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* 2. When a thread in the same process then uses the KCOV_SETBUFSIZE ioctl
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* on the block device, a Memory::Region is allocated and tracked via an
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* OwnPtr on the KCOVInstance.
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* 3. When a thread in the same process then uses the KCOV_ENABLE ioctl on
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* the block device, a flag is set in the Thread object and __sanitizer_cov_trace_pc
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* will start recording this threads visited code paths .
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* 3. When the same thread then uses the KCOV_DISABLE ioctl on the block device,
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* a flag is unset in the Thread object and __sanitizer_cov_trace_pc will
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* no longer record this threads visited code paths.
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* 4. When the Process dies, the KCOVInstance and Memory::Region are GCed.
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*/
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class KCOVInstance final {
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public:
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explicit KCOVInstance(ProcessID pid);
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ErrorOr<void> buffer_allocate(size_t buffer_size_in_entries);
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bool has_buffer() const { return m_buffer != nullptr; }
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void buffer_add_pc(u64 pc);
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Memory::VMObject* vmobject() { return m_vmobject; }
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Spinlock<LockRank::None>& spinlock() { return m_lock; }
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private:
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ProcessID m_pid { 0 };
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u64 m_buffer_size_in_entries { 0 };
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size_t m_buffer_size_in_bytes { 0 };
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kcov_pc_t* m_buffer { nullptr };
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LockRefPtr<Memory::AnonymousVMObject> m_vmobject;
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// Here to ensure it's not garbage collected at the end of open()
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OwnPtr<Memory::Region> m_kernel_region;
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Spinlock<LockRank::None> m_lock {};
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};
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}
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