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UserspaceEmulator: Load the target executable ELF semi-properly :^)

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This patch adds a basic ELF program loader to the UserspaceEmulator and
creates MMU regions for each PT_LOAD header. (Note that we don't yet
respect the R/W/X flags etc.)

We also turn the SoftCPU into an X86::InstructionStream and give it an
EIP register so we can actually execute code by fetching memory through
our MMU abstraction.
This commit is contained in:
Andreas Kling 2020-07-11 16:45:48 +02:00
parent 0eab5659f8
commit ae1d14bc7a
5 changed files with 68 additions and 22 deletions
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27
DevTools/UserspaceEmulator/Emulator.cpp
View file

@ -29,6 +29,7 @@
#include <AK/LogStream.h>
#include <Kernel/API/Syscall.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
namespace UserspaceEmulator {
@ -85,6 +86,8 @@ public:
*reinterpret_cast<u32*>(m_data + offset) = value;
}
u8* data() { return m_data; }
private:
u8* m_data { nullptr };
};
@ -107,12 +110,26 @@ void Emulator::setup_stack()
m_cpu.push32(0);
}
int Emulator::exec(X86::SimpleInstructionStream& stream, u32 base)
bool Emulator::load_elf(const ELF::Loader& elf)
{
elf.image().for_each_program_header([&](const ELF::Image::ProgramHeader& program_header) {
if (program_header.type() != PT_LOAD)
return;
auto region = make<SimpleRegion>(program_header.vaddr().get(), program_header.size_in_memory());
memcpy(region->data(), program_header.raw_data(), program_header.size_in_image());
mmu().add_region(move(region));
});
m_cpu.set_eip(elf.image().entry().get());
return true;
}
int Emulator::exec()
{
size_t offset = 0;
while (!m_shutdown) {
auto insn = X86::Instruction::from_stream(stream, true, true);
out() << "\033[33;1m" << insn.to_string(base + offset) << "\033[0m";
auto base_eip = m_cpu.eip();
auto insn = X86::Instruction::from_stream(m_cpu, true, true);
out() << "\033[33;1m" << insn.to_string(base_eip) << "\033[0m";
// FIXME: Remove this hack once it's no longer needed :^)
if (insn.mnemonic() == "RET")
@ -120,8 +137,6 @@ int Emulator::exec(X86::SimpleInstructionStream& stream, u32 base)
(m_cpu.*insn.handler())(insn);
m_cpu.dump();
offset += insn.length();
}
return m_exit_status;
}