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use armv4t_emu::{reg, Cpu, ExampleMem, Memory, Mode};
use crate::mem_sniffer::{AccessKind, MemSniffer};
use crate::DynResult;
const HLE_RETURN_ADDR: u32 = 0x12345678;
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum Event {
DoneStep,
Halted,
Break,
WatchWrite(u32),
WatchRead(u32),
}
pub enum ExecMode {
Step,
Continue,
RangeStep(u32, u32),
}
/// incredibly barebones armv4t-based emulator
pub struct Emu {
start_addr: u32,
// example custom register. only read/written to from the GDB client
pub(crate) custom_reg: u32,
pub(crate) exec_mode: ExecMode,
pub(crate) cpu: Cpu,
pub(crate) mem: ExampleMem,
pub(crate) watchpoints: Vec<u32>,
pub(crate) breakpoints: Vec<u32>,
pub(crate) files: Vec<Option<std::fs::File>>,
}
impl Emu {
pub fn new(program_elf: &[u8]) -> DynResult<Emu> {
// set up emulated system
let mut cpu = Cpu::new();
let mut mem = ExampleMem::new();
// load ELF
let elf_header = goblin::elf::Elf::parse(program_elf)?;
// copy all in-memory sections from the ELF file into system RAM
let sections = elf_header
.section_headers
.iter()
.filter(|h| h.is_alloc() && h.sh_type != goblin::elf::section_header::SHT_NOBITS);
for h in sections {
eprintln!(
"loading section {:?} into memory from [{:#010x?}..{:#010x?}]",
elf_header.shdr_strtab.get_at(h.sh_name).unwrap(),
h.sh_addr,
h.sh_addr + h.sh_size,
);
for (i, b) in program_elf[h.file_range().unwrap()].iter().enumerate() {
mem.w8(h.sh_addr as u32 + i as u32, *b);
}
}
// setup execution state
eprintln!("Setting PC to {:#010x?}", elf_header.entry);
cpu.reg_set(Mode::User, reg::SP, 0x10000000);
cpu.reg_set(Mode::User, reg::LR, HLE_RETURN_ADDR);
cpu.reg_set(Mode::User, reg::PC, elf_header.entry as u32);
cpu.reg_set(Mode::User, reg::CPSR, 0x10); // user mode
Ok(Emu {
start_addr: elf_header.entry as u32,
custom_reg: 0x12345678,
exec_mode: ExecMode::Continue,
cpu,
mem,
watchpoints: Vec::new(),
breakpoints: Vec::new(),
files: Vec::new(),
})
}
pub(crate) fn reset(&mut self) {
self.cpu.reg_set(Mode::User, reg::SP, 0x10000000);
self.cpu.reg_set(Mode::User, reg::LR, HLE_RETURN_ADDR);
self.cpu.reg_set(Mode::User, reg::PC, self.start_addr);
self.cpu.reg_set(Mode::User, reg::CPSR, 0x10);
}
/// single-step the interpreter
pub fn step(&mut self) -> Option<Event> {
let mut hit_watchpoint = None;
let mut sniffer = MemSniffer::new(&mut self.mem, &self.watchpoints, |access| {
hit_watchpoint = Some(access)
});
self.cpu.step(&mut sniffer);
let pc = self.cpu.reg_get(Mode::User, reg::PC);
if let Some(access) = hit_watchpoint {
let fixup = if self.cpu.thumb_mode() { 2 } else { 4 };
self.cpu.reg_set(Mode::User, reg::PC, pc - fixup);
return Some(match access.kind {
AccessKind::Read => Event::WatchRead(access.addr),
AccessKind::Write => Event::WatchWrite(access.addr),
});
}
if self.breakpoints.contains(&pc) {
return Some(Event::Break);
}
if pc == HLE_RETURN_ADDR {
return Some(Event::Halted);
}
None
}
/// run the emulator in accordance with the currently set `ExecutionMode`.
///
/// since the emulator runs in the same thread as the GDB loop, the emulator
/// will use the provided callback to poll the connection for incoming data
/// every 1024 steps.
pub fn run(&mut self, mut poll_incoming_data: impl FnMut() -> bool) -> RunEvent {
match self.exec_mode {
ExecMode::Step => RunEvent::Event(self.step().unwrap_or(Event::DoneStep)),
ExecMode::Continue => {
let mut cycles = 0;
loop {
if cycles % 1024 == 0 {
// poll for incoming data
if poll_incoming_data() {
break RunEvent::IncomingData;
}
}
cycles += 1;
if let Some(event) = self.step() {
break RunEvent::Event(event);
};
}
}
// just continue, but with an extra PC check
ExecMode::RangeStep(start, end) => {
let mut cycles = 0;
loop {
if cycles % 1024 == 0 {
// poll for incoming data
if poll_incoming_data() {
break RunEvent::IncomingData;
}
}
cycles += 1;
if let Some(event) = self.step() {
break RunEvent::Event(event);
};
if !(start..end).contains(&self.cpu.reg_get(self.cpu.mode(), reg::PC)) {
break RunEvent::Event(Event::DoneStep);
}
}
}
}
}
}
pub enum RunEvent {
IncomingData,
Event(Event),
}
|
