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[a64] Implement instruction stepping. 

Uses `0x0000'dead` as an instructon-stepping sentinel value.
Support for basic jumping instructions like `b`, `bl`, `br`, and `blr`.
This commit is contained in:
Wunkolo 2024-05-16 10:58:19 -07:00
parent f7bd0c89a3
commit c3efaaa286
1 changed files with 33 additions and 18 deletions
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51
src/xenia/cpu/backend/a64/a64_backend.cc
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@ -228,26 +228,41 @@ uint64_t A64Backend::CalculateNextHostInstruction(ThreadDebugInfo* thread_info,
insn.detail = &all_detail;
cs_disasm_iter(capstone_handle_, &machine_code_ptr,
&remaining_machine_code_size, &host_address, &insn);
auto& detail = all_detail.x86;
const auto& detail = all_detail.arm64;
switch (insn.id) {
case ARM64_INS_B:
case ARM64_INS_BL:
case ARM64_INS_BL: {
assert_true(detail.operands[0].type == ARM64_OP_IMM);
uint64_t target_pc = static_cast<uint64_t>(detail.operands[0].imm);
return current_pc + target_pc;
} break;
case ARM64_INS_BLR:
case ARM64_INS_BR:
case ARM64_INS_RET:
// todo(wunkolo): determine next instruction
default:
case ARM64_INS_BR: {
assert_true(detail.operands[0].type == ARM64_OP_REG);
uint64_t target_pc =
ReadCapstoneReg(&thread_info->host_context, detail.operands[0].reg);
return target_pc;
} break;
case ARM64_INS_RET: {
assert_zero(detail.op_count);
// Jump to link register
return thread_info->host_context.x[30];
} break;
case ARM64_INS_CBNZ:
case ARM64_INS_CBZ:
default: {
// Not a branching instruction - just move over it.
return current_pc + insn.size;
} break;
}
}
void A64Backend::InstallBreakpoint(Breakpoint* breakpoint) {
breakpoint->ForEachHostAddress([breakpoint](uint64_t host_address) {
auto ptr = reinterpret_cast<void*>(host_address);
auto original_bytes = xe::load_and_swap<uint16_t>(ptr);
assert_true(original_bytes != 0x0F0B);
xe::store_and_swap<uint16_t>(ptr, 0x0F0B);
auto original_bytes = xe::load_and_swap<uint32_t>(ptr);
assert_true(original_bytes != 0x0000'dead);
xe::store_and_swap<uint32_t>(ptr, 0x0000'dead);
breakpoint->backend_data().emplace_back(host_address, original_bytes);
});
}
@ -265,18 +280,18 @@ void A64Backend::InstallBreakpoint(Breakpoint* breakpoint, Function* fn) {
// Assume we haven't already installed a breakpoint in this spot.
auto ptr = reinterpret_cast<void*>(host_address);
auto original_bytes = xe::load_and_swap<uint16_t>(ptr);
assert_true(original_bytes != 0x0F0B);
xe::store_and_swap<uint16_t>(ptr, 0x0F0B);
auto original_bytes = xe::load_and_swap<uint32_t>(ptr);
assert_true(original_bytes != 0x0000'dead);
xe::store_and_swap<uint32_t>(ptr, 0x0000'dead);
breakpoint->backend_data().emplace_back(host_address, original_bytes);
}
void A64Backend::UninstallBreakpoint(Breakpoint* breakpoint) {
for (auto& pair : breakpoint->backend_data()) {
auto ptr = reinterpret_cast<uint8_t*>(pair.first);
auto instruction_bytes = xe::load_and_swap<uint16_t>(ptr);
assert_true(instruction_bytes == 0x0F0B);
xe::store_and_swap<uint16_t>(ptr, static_cast<uint16_t>(pair.second));
auto instruction_bytes = xe::load_and_swap<uint32_t>(ptr);
assert_true(instruction_bytes == 0x0000'dead);
xe::store_and_swap<uint32_t>(ptr, static_cast<uint32_t>(pair.second));
}
breakpoint->backend_data().clear();
}
@ -296,9 +311,9 @@ bool A64Backend::ExceptionCallback(Exception* ex) {
// Verify an expected illegal instruction.
auto instruction_bytes =
xe::load_and_swap<uint16_t>(reinterpret_cast<void*>(ex->pc()));
if (instruction_bytes != 0x0F0B) {
// Not our ud2 - not us.
xe::load_and_swap<uint32_t>(reinterpret_cast<void*>(ex->pc()));
if (instruction_bytes != 0x0000'dead) {
// Not our `udf #0xdead` - not us.
return false;
}