LosFuzzys / ebcvm

EFI Byte Code Virtual Machine in userspace

ebcvm

EFI Byte Code Virtual Machine in Userspace

ebcvm is a usermode EFI Byte Code (EBC) virtual machine. It supports all EBC instructions described in UEFI Specification. It also supports a few UEFI native code emulations and a simple debugger.

Building ebcvm

To build ebcvm, simply run:

$ make

This will build following executables.

• ebcvm: EBC VM
• tools/ebcdisas: Disassembler for EBC binaries
• tools/fnv1: Fowler-Noll-Vo hash tool

To run tests, run:

$ make test

Usage

Usage: ./ebcvm [OPTION] FILE
EFI Byte Code Interpreter
[OPTION]
  --debug={0,1}   debug mode
  --mem=INT   size of memory
  --stack=INT   size of stack
  --heap=INT    size of heap
  --step={0,1}    step execution
  --reloc={0,1}   relocate sections
  --help    show this help

Working with ELVM

Since there is no single EBC binary available in public, we created an EBC backend for ELVM.

To test EBC backend, run:

$ export PATH=`pwd`:$PATH
$ git clone https://github.com/retrage/elvm.git
$ cd elvm && git checkout retrage/ebc-v2
$ make ebc

The ELVM EBC backend will generate EBC binaries from EIR and C source code using modified 8cc.

EFI native code emulations

ebcvm has following native code emulations:

• EFI_BOOT_SERVICES.AllocatePool()
• EFI_SYSTEM_TABLE.ConIn.ReadKeyStroke()
• EFI_SYSTEM_TABLE.ConOut.OutputString()

License

ebcvm is released under the MIT license.