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c314292319
This patch introduces a "MallocTracer" to the UserspaceEmulator.
If this object is present on the Emulator, it can be notified whenever
the emulated program does a malloc() or free().
The notifications come in via a magic instruction sequence that we
embed in the LibC malloc() and free() functions. The sequence is:
"salc x2, push reg32 x2, pop reg32 x3"
The data about the malloc/free operation is in the three pushes.
We make sure the sequence is harmless when running natively.
Memory accesses on MmapRegion are then audited to see if they fall
inside a known-to-be-freed malloc chunk. If so, we complain loud
and red in the debugger output. :^)
This is very, very cool! :^)
It's also a whole lot slower than before, since now we're auditing
memory accesses against a new set of metadata. This will need to be
optimized (and running in this mode should be opt-in, perhaps even
a separate program, etc.)
64 lines
2.4 KiB
C++
64 lines
2.4 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include "SoftMMU.h"
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#include <sys/mman.h>
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namespace UserspaceEmulator {
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class MmapRegion final : public SoftMMU::Region {
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public:
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static NonnullOwnPtr<MmapRegion> create_anonymous(u32 base, u32 size, u32 prot);
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static NonnullOwnPtr<MmapRegion> create_file_backed(u32 base, u32 size, u32 prot, int flags, int fd, off_t offset);
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virtual ~MmapRegion() override;
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virtual u8 read8(u32 offset) override;
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virtual u16 read16(u32 offset) override;
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virtual u32 read32(u32 offset) override;
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virtual void write8(u32 offset, u8 value) override;
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virtual void write16(u32 offset, u16 value) override;
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virtual void write32(u32 offset, u32 value) override;
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u8* data() { return m_data; }
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bool is_readable() const { return m_prot & PROT_READ; }
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bool is_writable() const { return m_prot & PROT_WRITE; }
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bool is_executable() const { return m_prot & PROT_EXEC; }
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bool is_malloc_block() const;
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private:
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MmapRegion(u32 base, u32 size, int prot);
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u8* m_data { nullptr };
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int m_prot { 0 };
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bool m_file_backed { false };
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};
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}
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