eden/docs/dynarmic/README.md

Dynarmic
========

A dynamic recompiler for ARM.

Highlight features:

- Fast dynamic binary translation via Just-in-Time compilation
- Clean API
- Implemented in modern C++20
- Hooks exposed for easy code instrumentation
- Code injection support for very fine-grained instrumentation
- Support for unusual address space setups (bring-your-own memory system)
- Native support for most popular operating systems (Windows, macOS, Linux, FreeBSD, OpenBSD, NetBSD, Android)

*Please note that an adversarial guest program [can determine if it is being run under dynarmic](#disadvantages-of-dynarmic). Preventing this is not a goal of this project.*

### Supported guest architectures

* v3
* v4
* v4T
* v5TE
* v6K
* v6T2
* v7A
* 32-bit v8
* 64-bit v8

You can specify the specific guest version using [ArchVersion](src/dynarmic/interface/A32/arch_version.h).

There are no plans to support v1 or v2.

### Supported host architectures

* x86-64
* AArch64

There are no plans to support any 32-bit architecture.

Important API Changes in v6.x Series
------------------------------------

* **v6.7.0**
  * To support use cases where one wants to have the guest to have the same address space as the host, `nullptr` is now a valid value for `fastmem_pointer`.
    **This change is not backwards-compatible.** If you were previously using `nullptr` to represent an invalid fastmem arena, you will now have to use `std::nullopt`.


Documentation
-------------

Design documentation can be found at [./Design.md](./Design.md).


Usage Example
-------------

The below is a minimal example. Bring-your-own memory system.

```cpp
#include <array>
#include <cstdint>
#include <cstdio>
#include <exception>

#include "dynarmic/interface/A32/a32.h"
#include "dynarmic/interface/A32/config.h"

using u8 = std::uint8_t;
using u16 = std::uint16_t;
using u32 = std::uint32_t;
using u64 = std::uint64_t;

class MyEnvironment final : public Dynarmic::A32::UserCallbacks {
public:
    u64 ticks_left = 0;
    std::array<u8, 2048> memory{};

    u8 MemoryRead8(u32 vaddr) override {
        if (vaddr >= memory.size()) {
            return 0;
        }
        return memory[vaddr];
    }

    u16 MemoryRead16(u32 vaddr) override {
        return u16(MemoryRead8(vaddr)) | u16(MemoryRead8(vaddr + 1)) << 8;
    }

    u32 MemoryRead32(u32 vaddr) override {
        return u32(MemoryRead16(vaddr)) | u32(MemoryRead16(vaddr + 2)) << 16;
    }

    u64 MemoryRead64(u32 vaddr) override {
        return u64(MemoryRead32(vaddr)) | u64(MemoryRead32(vaddr + 4)) << 32;
    }

    void MemoryWrite8(u32 vaddr, u8 value) override {
        if (vaddr >= memory.size()) {
            return;
        }
        memory[vaddr] = value;
    }

    void MemoryWrite16(u32 vaddr, u16 value) override {
        MemoryWrite8(vaddr, u8(value));
        MemoryWrite8(vaddr + 1, u8(value >> 8));
    }

    void MemoryWrite32(u32 vaddr, u32 value) override {
        MemoryWrite16(vaddr, u16(value));
        MemoryWrite16(vaddr + 2, u16(value >> 16));
    }

    void MemoryWrite64(u32 vaddr, u64 value) override {
        MemoryWrite32(vaddr, u32(value));
        MemoryWrite32(vaddr + 4, u32(value >> 32));
    }

    void CallSVC(u32 swi) override {
        // Do something.
    }

    void ExceptionRaised(u32 pc, Dynarmic::A32::Exception exception) override {
        // Do something.
    }

    void AddTicks(u64 ticks) override {
        if (ticks > ticks_left) {
            ticks_left = 0;
            return;
        }
        ticks_left -= ticks;
    }

    u64 GetTicksRemaining() override {
        return ticks_left;
    }
};

int main(int argc, char** argv) {
    MyEnvironment env;
    Dynarmic::A32::UserConfig user_config;
    user_config.callbacks = &env;
    Dynarmic::A32::Jit cpu{user_config};

    // Execute at least 1 instruction.
    // (Note: More than one instruction may be executed.)
    env.ticks_left = 1;

    // Write some code to memory.
    env.MemoryWrite16(0, 0x0088); // lsls r0, r1, #2
    env.MemoryWrite16(2, 0xE7FE); // b +#0 (infinite loop)

    // Setup registers.
    cpu.Regs()[0] = 1;
    cpu.Regs()[1] = 2;
    cpu.Regs()[15] = 0; // PC = 0
    cpu.SetCpsr(0x00000030); // Thumb mode

    // Execute!
    cpu.Run();

    // Here we would expect cpu.Regs()[0] == 8
    printf("R0: %u\n", cpu.Regs()[0]);

    return 0;
}
```

Alternatives to Dynarmic
------------------------

Here are some projects with the same goals as dynarmic:

* [Unicorn](https://www.unicorn-engine.org/) - Recompiling multi-architecture CPU emulator, based on QEMU
* [SkyEye](http://skyeye.sourceforge.net) - Cached interpreter for ARM

More general alternatives:

* [tARMac](https://davidsharp.com/tarmac/) - Tarmac's use of armlets was initial inspiration for us to use an intermediate representation
* [QEMU](https://www.qemu.org/) - Recompiling multi-architecture system emulator
* [VisUAL](https://salmanarif.bitbucket.io/visual/index.html) - Visual ARM UAL emulator intended for education
* A wide variety of other recompilers, interpreters and emulators can be found embedded in other projects, here are some we would recommend looking at:
  * [firebird's recompiler](https://github.com/nspire-emus/firebird) - Takes more of a call-threaded approach to recompilation
  * [higan's arm7tdmi emulator](https://github.com/higan-emu/higan/tree/master/higan/component/processor/arm7tdmi) - Very clean code-style
  * [arm-js by ozaki-r](https://github.com/ozaki-r/arm-js) - Emulates ARMv7A and some peripherals of Versatile Express, in the browser

Disadvantages of Dynarmic
-------------------------

In the pursuit of speed, some behavior not commonly depended upon is elided. Therefore this emulator does not match spec.
Please note that this would mean that a guest application can easily determine if it is being run under instrumentation.

Known examples:

* Only user-mode is emulated, there is no emulation of any other privilege levels.
* FPSR state is approximate.
* Misaligned loads/stores are not appropriately trapped in certain cases.
* Exclusive monitor behavior may not match any known physical processor.

No formal verification has been done, and no security assessment has been made.
Use this code base at your own risk.

Legal
-----

dynarmic is under a 0BSD license. See LICENSE.txt for more details.

dynarmic uses several other libraries, whose licenses are included below:

### biscuit

```
Copyright 2021 Lioncash/Lioncache

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
IN THE SOFTWARE.
```

### catch

```
Boost Software License - Version 1.0 - August 17th, 2003

Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
this license (the "Software") to use, reproduce, display, distribute,
execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:

The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software, in whole or in part, and
all derivative works of the Software, unless such copies or derivative
works are solely in the form of machine-executable object code generated by
a source language processor.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
```

### fmt

```
Copyright (c) 2012 - 2016, Victor Zverovich

All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
```

### mcl & oaknut

```
MIT License

Copyright (c) 2022 merryhime <https://mary.rs>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
```

### unordered_dense

```
MIT License

Copyright (c) 2022 Martin Leitner-Ankerl

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
```

### xbyak

```
Copyright (c) 2007 MITSUNARI Shigeo
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
Neither the name of the copyright owner nor the names of its contributors may
be used to endorse or promote products derived from this software without
specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
THE POSSIBILITY OF SUCH DAMAGE.
-----------------------------------------------------------------------------
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問わず、かつ責任の根拠が契約であるか厳格責任であるか（過失その他の）不法行為で
あるかを問わず、仮にそのような損害が発生する可能性を知らされていたとしても、
本ソフトウェアの使用によって発生した（代替品または代用サービスの調達、使用の
喪失、データの喪失、利益の喪失、業務の中断も含め、またそれに限定されない）直接
損害、間接損害、偶発的な損害、特別損害、懲罰的損害、または結果損害について、
一切責任を負わないものとします。
```