// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include "common/arm64/native_clock.h"
#include "common/bit_cast.h"
#include "common/literals.h"
#include "core/arm/nce/arm_nce.h"
#include "core/arm/nce/guest_context.h"
#include "core/arm/nce/instructions.h"
#include "core/arm/nce/patcher.h"
#include "core/core.h"
#include "core/core_timing.h"
#include "core/hle/kernel/svc.h"
namespace Core::NCE {
using namespace Common::Literals;
using namespace oaknut::util;
using NativeExecutionParameters = Kernel::KThread::NativeExecutionParameters;
constexpr size_t MaxRelativeBranch = 128_MiB;
constexpr u32 ModuleCodeIndex = 0x24 / sizeof(u32);
Patcher::Patcher() : c(m_patch_instructions) {}
Patcher::~Patcher() = default;
void Patcher::PatchText(const Kernel::PhysicalMemory& program_image,
const Kernel::CodeSet::Segment& code) {
// Branch to the first instruction of the module.
this->BranchToModule(0);
// Write save context helper function.
c.l(m_save_context);
WriteSaveContext();
// Write load context helper function.
c.l(m_load_context);
WriteLoadContext();
// Retrieve text segment data.
const auto text = std::span{program_image}.subspan(code.offset, code.size);
const auto text_words =
std::span<const u32>{reinterpret_cast<const u32*>(text.data()), text.size() / sizeof(u32)};
// Loop through instructions, patching as needed.
for (u32 i = ModuleCodeIndex; i < static_cast<u32>(text_words.size()); i++) {
const u32 inst = text_words[i];
const auto AddRelocations = [&] {
const uintptr_t this_offset = i * sizeof(u32);
const uintptr_t next_offset = this_offset + sizeof(u32);
// Relocate from here to patch.
this->BranchToPatch(this_offset);
// Relocate from patch to next instruction.
return next_offset;
};
// SVC
if (auto svc = SVC{inst}; svc.Verify()) {
WriteSvcTrampoline(AddRelocations(), svc.GetValue());
continue;
}
// MRS Xn, TPIDR_EL0
// MRS Xn, TPIDRRO_EL0
if (auto mrs = MRS{inst};
mrs.Verify() && (mrs.GetSystemReg() == TpidrroEl0 || mrs.GetSystemReg() == TpidrEl0)) {
const auto src_reg = mrs.GetSystemReg() == TpidrroEl0 ? oaknut::SystemReg::TPIDRRO_EL0
: oaknut::SystemReg::TPIDR_EL0;
const auto dest_reg = oaknut::XReg{static_cast<int>(mrs.GetRt())};
WriteMrsHandler(AddRelocations(), dest_reg, src_reg);
continue;
}
// MRS Xn, CNTPCT_EL0
if (auto mrs = MRS{inst}; mrs.Verify() && mrs.GetSystemReg() == CntpctEl0) {
WriteCntpctHandler(AddRelocations(), oaknut::XReg{static_cast<int>(mrs.GetRt())});
continue;
}
// MRS Xn, CNTFRQ_EL0
if (auto mrs = MRS{inst}; mrs.Verify() && mrs.GetSystemReg() == CntfrqEl0) {
UNREACHABLE();
}
// MSR TPIDR_EL0, Xn
if (auto msr = MSR{inst}; msr.Verify() && msr.GetSystemReg() == TpidrEl0) {
WriteMsrHandler(AddRelocations(), oaknut::XReg{static_cast<int>(msr.GetRt())});
continue;
}
if (auto exclusive = Exclusive{inst}; exclusive.Verify()) {
m_exclusives.push_back(i);
}
}
// Determine patching mode for the final relocation step
const size_t image_size = program_image.size();
this->mode = image_size > MaxRelativeBranch ? PatchMode::PreText : PatchMode::PostData;
}
void Patcher::RelocateAndCopy(Common::ProcessAddress load_base,
const Kernel::CodeSet::Segment& code,
Kernel::PhysicalMemory& program_image,
EntryTrampolines* out_trampolines) {
const size_t patch_size = GetSectionSize();
const size_t image_size = program_image.size();
// Retrieve text segment data.
const auto text = std::span{program_image}.subspan(code.offset, code.size);
const auto text_words =
std::span<u32>{reinterpret_cast<u32*>(text.data()), text.size() / sizeof(u32)};
const auto ApplyBranchToPatchRelocation = [&](u32* target, const Relocation& rel) {
oaknut::CodeGenerator rc{target};
if (mode == PatchMode::PreText) {
rc.B(rel.patch_offset - patch_size - rel.module_offset);
} else {
rc.B(image_size - rel.module_offset + rel.patch_offset);
}
};
const auto ApplyBranchToModuleRelocation = [&](u32* target, const Relocation& rel) {
oaknut::CodeGenerator rc{target};
if (mode == PatchMode::PreText) {
rc.B(patch_size - rel.patch_offset + rel.module_offset);
} else {
rc.B(rel.module_offset - image_size - rel.patch_offset);
}
};
const auto RebasePatch = [&](ptrdiff_t patch_offset) {
if (mode == PatchMode::PreText) {
return GetInteger(load_base) + patch_offset;
} else {
return GetInteger(load_base) + image_size + patch_offset;
}
};
const auto RebasePc = [&](uintptr_t module_offset) {
if (mode == PatchMode::PreText) {
return GetInteger(load_base) + patch_size + module_offset;
} else {
return GetInteger(load_base) + module_offset;
}
};
// We are now ready to relocate!
for (const Relocation& rel : m_branch_to_patch_relocations) {
ApplyBranchToPatchRelocation(text_words.data() + rel.module_offset / sizeof(u32), rel);
}
for (const Relocation& rel : m_branch_to_module_relocations) {
ApplyBranchToModuleRelocation(m_patch_instructions.data() + rel.patch_offset / sizeof(u32),
rel);
}
// Rewrite PC constants and record post trampolines
for (const Relocation& rel : m_write_module_pc_relocations) {
oaknut::CodeGenerator rc{m_patch_instructions.data() + rel.patch_offset / sizeof(u32)};
rc.dx(RebasePc(rel.module_offset));
}
for (const Trampoline& rel : m_trampolines) {
out_trampolines->insert({RebasePc(rel.module_offset), RebasePatch(rel.patch_offset)});
}
// Cortex-A57 seems to treat all exclusives as ordered, but newer processors do not.
// Convert to ordered to preserve this assumption.
for (const ModuleTextAddress i : m_exclusives) {
auto exclusive = Exclusive{text_words[i]};
text_words[i] = exclusive.AsOrdered();
}
// Copy to program image
if (this->mode == PatchMode::PreText) {
std::memcpy(program_image.data(), m_patch_instructions.data(),
m_patch_instructions.size() * sizeof(u32));
} else {
program_image.resize(image_size + patch_size);
std::memcpy(program_image.data() + image_size, m_patch_instructions.data(),
m_patch_instructions.size() * sizeof(u32));
}
}
size_t Patcher::GetSectionSize() const noexcept {
return Common::AlignUp(m_patch_instructions.size() * sizeof(u32), Core::Memory::YUZU_PAGESIZE);
}
void Patcher::WriteLoadContext() {
// This function was called, which modifies X30, so use that as a scratch register.
// SP contains the guest X30, so save our return X30 to SP + 8, since we have allocated 16 bytes
// of stack.
c.STR(X30, SP, 8);
c.MRS(X30, oaknut::SystemReg::TPIDR_EL0);
c.LDR(X30, X30, offsetof(NativeExecutionParameters, native_context));
// Load system registers.
c.LDR(W0, X30, offsetof(GuestContext, fpsr));
c.MSR(oaknut::SystemReg::FPSR, X0);
c.LDR(W0, X30, offsetof(GuestContext, fpcr));
c.MSR(oaknut::SystemReg::FPCR, X0);
c.LDR(W0, X30, offsetof(GuestContext, nzcv));
c.MSR(oaknut::SystemReg::NZCV, X0);
// Load all vector registers.
static constexpr size_t VEC_OFF = offsetof(GuestContext, vector_registers);
for (int i = 0; i <= 30; i += 2) {
c.LDP(oaknut::QReg{i}, oaknut::QReg{i + 1}, X30, VEC_OFF + 16 * i);
}
// Load all general-purpose registers except X30.
for (int i = 0; i <= 28; i += 2) {
c.LDP(oaknut::XReg{i}, oaknut::XReg{i + 1}, X30, 8 * i);
}
// Reload our return X30 from the stack and return.
// The patch code will reload the guest X30 for us.
c.LDR(X30, SP, 8);
c.RET();
}
void Patcher::WriteSaveContext() {
// This function was called, which modifies X30, so use that as a scratch register.
// SP contains the guest X30, so save our X30 to SP + 8, since we have allocated 16 bytes of
// stack.
c.STR(X30, SP, 8);
c.MRS(X30, oaknut::SystemReg::TPIDR_EL0);
c.LDR(X30, X30, offsetof(NativeExecutionParameters, native_context));
// Store all general-purpose registers except X30.
for (int i = 0; i <= 28; i += 2) {
c.STP(oaknut::XReg{i}, oaknut::XReg{i + 1}, X30, 8 * i);
}
// Store all vector registers.
static constexpr size_t VEC_OFF = offsetof(GuestContext, vector_registers);
for (int i = 0; i <= 30; i += 2) {
c.STP(oaknut::QReg{i}, oaknut::QReg{i + 1}, X30, VEC_OFF + 16 * i);
}
// Store guest system registers, X30 and SP, using X0 as a scratch register.
c.STR(X0, SP, PRE_INDEXED, -16);
c.LDR(X0, SP, 16);
c.STR(X0, X30, 8 * 30);
c.ADD(X0, SP, 32);
c.STR(X0, X30, offsetof(GuestContext, sp));
c.MRS(X0, oaknut::SystemReg::FPSR);
c.STR(W0, X30, offsetof(GuestContext, fpsr));
c.MRS(X0, oaknut::SystemReg::FPCR);
c.STR(W0, X30, offsetof(GuestContext, fpcr));
c.MRS(X0, oaknut::SystemReg::NZCV);
c.STR(W0, X30, offsetof(GuestContext, nzcv));
c.LDR(X0, SP, POST_INDEXED, 16);
// Reload our return X30 from the stack, and return.
c.LDR(X30, SP, 8);
c.RET();
}
void Patcher::WriteSvcTrampoline(ModuleDestLabel module_dest, u32 svc_id) {
// We are about to start saving state, so we need to lock the context.
this->LockContext();
// Store guest X30 to the stack. Then, save the context and restore the stack.
// This will save all registers except PC, but we know PC at patch time.
c.STR(X30, SP, PRE_INDEXED, -16);
c.BL(m_save_context);
c.LDR(X30, SP, POST_INDEXED, 16);
// Now that we've saved all registers, we can use any registers as scratch.
// Store PC + 4 to arm interface, since we know the instruction offset from the entry point.
oaknut::Label pc_after_svc;
c.MRS(X1, oaknut::SystemReg::TPIDR_EL0);
c.LDR(X1, X1, offsetof(NativeExecutionParameters, native_context));
c.LDR(X2, pc_after_svc);
c.STR(X2, X1, offsetof(GuestContext, pc));
// Store SVC number to execute when we return
c.MOV(X2, svc_id);
c.STR(W2, X1, offsetof(GuestContext, svc_swi));
// We are calling a SVC. Clear esr_el1 and return it.
static_assert(std::is_same_v<std::underlying_type_t<HaltReason>, u64>);
oaknut::Label retry;
c.ADD(X2, X1, offsetof(GuestContext, esr_el1));
c.l(retry);
c.LDAXR(X0, X2);
c.STLXR(W3, XZR, X2);
c.CBNZ(W3, retry);
// Add "calling SVC" flag. Since this is X0, this is now our return value.
c.ORR(X0, X0, static_cast<u64>(HaltReason::SupervisorCall));
// Offset the GuestContext pointer to the HostContext member.
// STP has limited range of [-512, 504] which we can't reach otherwise
// NB: Due to this all offsets below are from the start of HostContext.
c.ADD(X1, X1, offsetof(GuestContext, host_ctx));
// Reload host TPIDR_EL0 and SP.
static_assert(offsetof(HostContext, host_sp) + 8 == offsetof(HostContext, host_tpidr_el0));
c.LDP(X2, X3, X1, offsetof(HostContext, host_sp));
c.MOV(SP, X2);
c.MSR(oaknut::SystemReg::TPIDR_EL0, X3);
// Load callee-saved host registers and return to host.
static constexpr size_t HOST_REGS_OFF = offsetof(HostContext, host_saved_regs);
static constexpr size_t HOST_VREGS_OFF = offsetof(HostContext, host_saved_vregs);
c.LDP(X19, X20, X1, HOST_REGS_OFF);
c.LDP(X21, X22, X1, HOST_REGS_OFF + 2 * sizeof(u64));
c.LDP(X23, X24, X1, HOST_REGS_OFF + 4 * sizeof(u64));
c.LDP(X25, X26, X1, HOST_REGS_OFF + 6 * sizeof(u64));
c.LDP(X27, X28, X1, HOST_REGS_OFF + 8 * sizeof(u64));
c.LDP(X29, X30, X1, HOST_REGS_OFF + 10 * sizeof(u64));
c.LDP(Q8, Q9, X1, HOST_VREGS_OFF);
c.LDP(Q10, Q11, X1, HOST_VREGS_OFF + 2 * sizeof(u128));
c.LDP(Q12, Q13, X1, HOST_VREGS_OFF + 4 * sizeof(u128));
c.LDP(Q14, Q15, X1, HOST_VREGS_OFF + 6 * sizeof(u128));
c.RET();
// Write the post-SVC trampoline address, which will jump back to the guest after restoring its
// state.
m_trampolines.push_back({c.offset(), module_dest});
// Host called this location. Save the return address so we can
// unwind the stack properly when jumping back.
c.MRS(X2, oaknut::SystemReg::TPIDR_EL0);
c.LDR(X2, X2, offsetof(NativeExecutionParameters, native_context));
c.ADD(X0, X2, offsetof(GuestContext, host_ctx));
c.STR(X30, X0, offsetof(HostContext, host_saved_regs) + 11 * sizeof(u64));
// Reload all guest registers except X30 and PC.
// The function also expects 16 bytes of stack already allocated.
c.STR(X30, SP, PRE_INDEXED, -16);
c.BL(m_load_context);
c.LDR(X30, SP, POST_INDEXED, 16);
// Use X1 as a scratch register to restore X30.
c.STR(X1, SP, PRE_INDEXED, -16);
c.MRS(X1, oaknut::SystemReg::TPIDR_EL0);
c.LDR(X1, X1, offsetof(NativeExecutionParameters, native_context));
c.LDR(X30, X1, offsetof(GuestContext, cpu_registers) + sizeof(u64) * 30);
c.LDR(X1, SP, POST_INDEXED, 16);
// Unlock the context.
this->UnlockContext();
// Jump back to the instruction after the emulated SVC.
this->BranchToModule(module_dest);
// Store PC after call.
c.l(pc_after_svc);
this->WriteModulePc(module_dest);
}
void Patcher::WriteMrsHandler(ModuleDestLabel module_dest, oaknut::XReg dest_reg,
oaknut::SystemReg src_reg) {
// Retrieve emulated TLS register from GuestContext.
c.MRS(dest_reg, oaknut::SystemReg::TPIDR_EL0);
if (src_reg == oaknut::SystemReg::TPIDRRO_EL0) {
c.LDR(dest_reg, dest_reg, offsetof(NativeExecutionParameters, tpidrro_el0));
} else {
c.LDR(dest_reg, dest_reg, offsetof(NativeExecutionParameters, tpidr_el0));
}
// Jump back to the instruction after the emulated MRS.
this->BranchToModule(module_dest);
}
void Patcher::WriteMsrHandler(ModuleDestLabel module_dest, oaknut::XReg src_reg) {
const auto scratch_reg = src_reg.index() == 0 ? X1 : X0;
c.STR(scratch_reg, SP, PRE_INDEXED, -16);
// Save guest value to NativeExecutionParameters::tpidr_el0.
c.MRS(scratch_reg, oaknut::SystemReg::TPIDR_EL0);
c.STR(src_reg, scratch_reg, offsetof(NativeExecutionParameters, tpidr_el0));
// Restore scratch register.
c.LDR(scratch_reg, SP, POST_INDEXED, 16);
// Jump back to the instruction after the emulated MSR.
this->BranchToModule(module_dest);
}
void Patcher::WriteCntpctHandler(ModuleDestLabel module_dest, oaknut::XReg dest_reg) {
static Common::Arm64::NativeClock clock{};
const auto factor = clock.GetGuestCNTFRQFactor();
const auto raw_factor = Common::BitCast<std::array<u64, 2>>(factor);
const auto use_x2_x3 = dest_reg.index() == 0 || dest_reg.index() == 1;
oaknut::XReg scratch0 = use_x2_x3 ? X2 : X0;
oaknut::XReg scratch1 = use_x2_x3 ? X3 : X1;
oaknut::Label factorlo;
oaknut::Label factorhi;
// Save scratches.
c.STP(scratch0, scratch1, SP, PRE_INDEXED, -16);
// Load counter value.
c.MRS(dest_reg, oaknut::SystemReg::CNTVCT_EL0);
// Load scaling factor.
c.LDR(scratch0, factorlo);
c.LDR(scratch1, factorhi);
// Multiply low bits and get result.
c.UMULH(scratch0, dest_reg, scratch0);
// Multiply high bits and add low bit result.
c.MADD(dest_reg, dest_reg, scratch1, scratch0);
// Reload scratches.
c.LDP(scratch0, scratch1, SP, POST_INDEXED, 16);
// Jump back to the instruction after the emulated MRS.
this->BranchToModule(module_dest);
// Scaling factor constant values.
c.l(factorlo);
c.dx(raw_factor[0]);
c.l(factorhi);
c.dx(raw_factor[1]);
}
void Patcher::LockContext() {
oaknut::Label retry;
// Save scratches.
c.STP(X0, X1, SP, PRE_INDEXED, -16);
// Reload lock pointer.
c.l(retry);
c.CLREX();
c.MRS(X0, oaknut::SystemReg::TPIDR_EL0);
c.ADD(X0, X0, offsetof(NativeExecutionParameters, lock));
static_assert(SpinLockLocked == 0);
// Load-linked with acquire ordering.
c.LDAXR(W1, X0);
// If the value was SpinLockLocked, clear monitor and retry.
c.CBZ(W1, retry);
// Store-conditional SpinLockLocked with relaxed ordering.
c.STXR(W1, WZR, X0);
// If we failed to store, retry.
c.CBNZ(W1, retry);
// We succeeded! Reload scratches.
c.LDP(X0, X1, SP, POST_INDEXED, 16);
}
void Patcher::UnlockContext() {
// Save scratches.
c.STP(X0, X1, SP, PRE_INDEXED, -16);
// Load lock pointer.
c.MRS(X0, oaknut::SystemReg::TPIDR_EL0);
c.ADD(X0, X0, offsetof(NativeExecutionParameters, lock));
// Load SpinLockUnlocked.
c.MOV(W1, SpinLockUnlocked);
// Store value with release ordering.
c.STLR(W1, X0);
// Load scratches.
c.LDP(X0, X1, SP, POST_INDEXED, 16);
}
} // namespace Core::NCE