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Ryan Houdek
4f93259332
Due to how we emulate the guest signal handlers, we do the state setup in the real host signal handler, then we jump out after state setup. This was causing a situation where we were setting up the guest signal handler state with the correct sa_mask. Then after setting up the guest state we would leave the FEX signal handler, restoring the signal mask to our original mask. Instead now as we are setting up the guest state, we save our host signal mask. Then on signal handler return we modify our host signal mask to match what the guest wants. Once we hit our sigreturn emulation we then restore the original signal mask. This looks to improve some stability problems regarding how wine uses signals but it still doesn't fix the gvisor test sadly.
FEXCore - Fast x86 Core emulation library
This is the core emulation library that is used for the FEX emulator project. This project aims to provide a fast and functional x86-64 emulation library that can meet and surpass other x86-64 emulation libraries.
Goals
- Be as fast as possible, beating and exceeding current options for x86-64 emulation
- 25% - 50% lower performance than native code would be desired target
- Use an IR to efficiently translate x86-64 to our host architecture
- Support a tiered recompiler to allow for fast runtime performance
- Support offline compilation and offline tooling for inspection and performance analysis
- Support threaded emulation. Including emulating x86-64's strong memory model on weak memory model architectures
- Support a significant portion of the x86-64 instruction space.
- Including MMX, SSE, SSE2, SSE3, SSSE3, and SSE4*
- Support fallback routines for uncommonly used x86-64 instructions
- Including x87 and 3DNow!
- Only support userspace emulation.
- All x86-64 instructions run as if they are under CPL-3(userland) security layer
- Minimal Linux Syscall emulation for testing purposes
- Portable library implementation in order to support easy integration in to applications
Target Host Architecture
The target host architecture for this library is AArch64. Specifically the ARMv8.1 version or newer. The CPU IR is designed with AArch64 in mind but there is a desire to run the recompiled code on other architectures as well. Multiple architecture support is desired for easier bringup and debugging, performance isn't as much of a priority there (ex. x86-64(guest) translated to x86-64(host))
Not currently goals but will be in the future
- 32bit x86 support
- This will be a desire in the future, but to lower the amount of work required, decided to push this off for now.
- Integration in to WINE
- Later generation of x86-64 instruction sets
- Including AVX, F16C, XOP, FMA, AVX2, etc
Not desired
- Kernel space emulation
- CPL0-2 emulation
- Real Mode, Protected Mode, Virtual-8086 Mode, System Management Mode
- IRQs
- SVM
- "Cycle Accurate" emulation
Dependencies
- clang-tidy if you want to ensure the code stays tidy
- cmake
- A C++17 compliant compiler (There are assumptions made about using Clang and LTO)