Atmosphere/libraries/libmesosphere/source/arch/arm64/kern_exception_handlers.cpp

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/*
* Copyright (c) Atmosphère-NX
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*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <mesosphere.hpp>
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namespace ams::kern::svc {
void RestoreContext(uintptr_t sp);
}
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namespace ams::kern::arch::arm64 {
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namespace {
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enum EsrEc : u32 {
EsrEc_Unknown = 0b000000,
EsrEc_WaitForInterruptOrEvent = 0b000001,
EsrEc_Cp15McrMrc = 0b000011,
EsrEc_Cp15McrrMrrc = 0b000100,
EsrEc_Cp14McrMrc = 0b000101,
EsrEc_FpAccess = 0b000111,
EsrEc_Cp14Mrrc = 0b001100,
EsrEc_BranchTarget = 0b001101,
EsrEc_IllegalExecution = 0b001110,
EsrEc_Svc32 = 0b010001,
EsrEc_Svc64 = 0b010101,
EsrEc_SystemInstruction64 = 0b011000,
EsrEc_SveZen = 0b011001,
EsrEc_PointerAuthInstruction = 0b011100,
EsrEc_InstructionAbortEl0 = 0b100000,
EsrEc_InstructionAbortEl1 = 0b100001,
EsrEc_PcAlignmentFault = 0b100010,
EsrEc_DataAbortEl0 = 0b100100,
EsrEc_DataAbortEl1 = 0b100101,
EsrEc_SpAlignmentFault = 0b100110,
EsrEc_FpException32 = 0b101000,
EsrEc_FpException64 = 0b101100,
EsrEc_SErrorInterrupt = 0b101111,
EsrEc_BreakPointEl0 = 0b110000,
EsrEc_BreakPointEl1 = 0b110001,
EsrEc_SoftwareStepEl0 = 0b110010,
EsrEc_SoftwareStepEl1 = 0b110011,
EsrEc_WatchPointEl0 = 0b110100,
EsrEc_WatchPointEl1 = 0b110101,
EsrEc_BkptInstruction = 0b111000,
EsrEc_BrkInstruction = 0b111100,
};
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constexpr u32 GetInstructionData(const KExceptionContext *context, u64 esr) {
/* Check for THUMB usermode */
if ((context->psr & 0x3F) == 0x30) {
u32 insn = *reinterpret_cast<u16 *>(context->pc & ~0x1);
/* Check if the instruction was 32-bit. */
if ((esr >> 25) & 1) {
insn = (insn << 16) | *reinterpret_cast<u16 *>((context->pc & ~0x1) + sizeof(u16));
}
return insn;
} else {
/* Not thumb, so just get the instruction. */
return *reinterpret_cast<u32 *>(context->pc);
}
}
void HandleUserException(KExceptionContext *context, u64 esr, u64 far, u64 afsr0, u64 afsr1, u32 data) {
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KProcess &cur_process = GetCurrentProcess();
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bool should_process_user_exception = KTargetSystem::IsUserExceptionHandlersEnabled();
const u64 ec = (esr >> 26) & 0x3F;
switch (ec) {
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case EsrEc_Unknown:
case EsrEc_IllegalExecution:
case EsrEc_Svc32:
case EsrEc_Svc64:
case EsrEc_PcAlignmentFault:
case EsrEc_SpAlignmentFault:
case EsrEc_SErrorInterrupt:
case EsrEc_BreakPointEl0:
case EsrEc_SoftwareStepEl0:
case EsrEc_WatchPointEl0:
case EsrEc_BkptInstruction:
case EsrEc_BrkInstruction:
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break;
default:
{
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/* If the fault address's state is KMemoryState_Code and the user can't read the address, force processing exception. */
KMemoryInfo info;
ams::svc::PageInfo pi;
if (R_SUCCEEDED(cur_process.GetPageTable().QueryInfo(std::addressof(info), std::addressof(pi), far))) {
if (info.GetState() == KMemoryState_Code && ((info.GetPermission() & KMemoryPermission_UserRead) != KMemoryPermission_UserRead)) {
should_process_user_exception = true;
}
}
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}
break;
}
/* In the event that we return from this exception, we want SPSR.SS set so that we advance an instruction if single-stepping. */
#if defined(MESOSPHERE_ENABLE_HARDWARE_SINGLE_STEP)
context->psr |= (1ul << 21);
#endif
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/* If we should process the user exception (and it's not a breakpoint), try to enter. */
const bool is_software_break = (ec == EsrEc_Unknown || ec == EsrEc_IllegalExecution || ec == EsrEc_BkptInstruction || ec == EsrEc_BrkInstruction);
const bool is_breakpoint = (ec == EsrEc_BreakPointEl0 || ec == EsrEc_SoftwareStepEl0 || ec == EsrEc_WatchPointEl0);
if ((should_process_user_exception) &&
!(is_software_break && cur_process.IsAttachedToDebugger() && KDebug::IsBreakInstruction(data, context->psr)) &&
!(is_breakpoint))
{
if (cur_process.EnterUserException()) {
/* Fill out the exception info. */
const bool is_aarch64 = (context->psr & 0x10) == 0;
if (is_aarch64) {
/* 64-bit. */
ams::svc::aarch64::ExceptionInfo *info = std::addressof(static_cast<ams::svc::aarch64::ProcessLocalRegion *>(cur_process.GetProcessLocalRegionHeapAddress())->exception_info);
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for (size_t i = 0; i < util::size(info->r); ++i) {
info->r[i] = context->x[i];
}
info->sp = context->sp;
info->lr = context->x[30];
info->pc = context->pc;
info->pstate = (context->psr & cpu::El0Aarch64PsrMask);
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info->afsr0 = afsr0;
info->afsr1 = afsr1;
info->esr = esr;
info->far = far;
} else {
/* 32-bit. */
ams::svc::aarch32::ExceptionInfo *info = std::addressof(static_cast<ams::svc::aarch32::ProcessLocalRegion *>(cur_process.GetProcessLocalRegionHeapAddress())->exception_info);
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for (size_t i = 0; i < util::size(info->r); ++i) {
info->r[i] = context->x[i];
}
info->sp = context->x[13];
info->lr = context->x[14];
info->pc = context->pc;
info->flags = 1;
info->status_64.pstate = (context->psr & cpu::El0Aarch32PsrMask);
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info->status_64.afsr0 = afsr0;
info->status_64.afsr1 = afsr1;
info->status_64.esr = esr;
info->status_64.far = far;
}
/* Save the debug parameters to the current thread. */
GetCurrentThread().SaveDebugParams(far, esr, data);
/* Get the exception type. */
u32 type;
switch (ec) {
case EsrEc_Unknown:
case EsrEc_IllegalExecution:
case EsrEc_Cp15McrMrc:
case EsrEc_Cp15McrrMrrc:
case EsrEc_Cp14McrMrc:
case EsrEc_Cp14Mrrc:
case EsrEc_SystemInstruction64:
case EsrEc_BkptInstruction:
case EsrEc_BrkInstruction:
type = ams::svc::ExceptionType_InstructionAbort;
break;
case EsrEc_PcAlignmentFault:
type = ams::svc::ExceptionType_UnalignedInstruction;
break;
case EsrEc_SpAlignmentFault:
type = ams::svc::ExceptionType_UnalignedData;
break;
case EsrEc_Svc32:
case EsrEc_Svc64:
type = ams::svc::ExceptionType_InvalidSystemCall;
break;
case EsrEc_SErrorInterrupt:
type = ams::svc::ExceptionType_MemorySystemError;
break;
case EsrEc_InstructionAbortEl0:
type = ams::svc::ExceptionType_InstructionAbort;
break;
case EsrEc_DataAbortEl0:
default:
type = ams::svc::ExceptionType_DataAbort;
break;
}
/* We want to enter at the process entrypoint, with x0 = type. */
context->pc = GetInteger(cur_process.GetEntryPoint());
context->x[0] = type;
if (is_aarch64) {
context->x[1] = GetInteger(cur_process.GetProcessLocalRegionAddress() + AMS_OFFSETOF(ams::svc::aarch64::ProcessLocalRegion, exception_info));
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const auto *plr = GetPointer<ams::svc::aarch64::ProcessLocalRegion>(cur_process.GetProcessLocalRegionAddress());
context->sp = util::AlignDown(reinterpret_cast<uintptr_t>(plr->data) + sizeof(plr->data), 0x10);
context->psr = 0;
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} else {
context->x[1] = GetInteger(cur_process.GetProcessLocalRegionAddress() + AMS_OFFSETOF(ams::svc::aarch32::ProcessLocalRegion, exception_info));
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const auto *plr = GetPointer<ams::svc::aarch32::ProcessLocalRegion>(cur_process.GetProcessLocalRegionAddress());
context->x[13] = util::AlignDown(reinterpret_cast<uintptr_t>(plr->data) + sizeof(plr->data), 0x08);
context->psr = 0x10;
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}
/* Process that we're entering a usermode exception on the current thread. */
GetCurrentThread().OnEnterUsermodeException();
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return;
}
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}
/* If we should, clear the thread's state as single-step. */
#if defined(MESOSPHERE_ENABLE_HARDWARE_SINGLE_STEP)
if (AMS_UNLIKELY(GetCurrentThread().IsHardwareSingleStep())) {
GetCurrentThread().ClearHardwareSingleStep();
cpu::MonitorDebugSystemControlRegisterAccessor().SetSoftwareStep(false).Store();
cpu::InstructionMemoryBarrier();
}
#endif
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{
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/* Collect additional information based on the ec. */
uintptr_t params[3] = {};
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switch (ec) {
case EsrEc_Unknown:
case EsrEc_IllegalExecution:
case EsrEc_BkptInstruction:
case EsrEc_BrkInstruction:
{
params[0] = ams::svc::DebugException_UndefinedInstruction;
params[1] = far;
params[2] = data;
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}
break;
case EsrEc_PcAlignmentFault:
case EsrEc_SpAlignmentFault:
{
params[0] = ams::svc::DebugException_AlignmentFault;
params[1] = far;
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}
break;
case EsrEc_Svc32:
case EsrEc_Svc64:
{
params[0] = ams::svc::DebugException_UndefinedSystemCall;
params[1] = far;
params[2] = (esr & 0xFF);
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}
break;
case EsrEc_BreakPointEl0:
case EsrEc_SoftwareStepEl0:
{
params[0] = ams::svc::DebugException_BreakPoint;
params[1] = far;
params[2] = ams::svc::BreakPointType_HardwareInstruction;
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}
break;
case EsrEc_WatchPointEl0:
{
params[0] = ams::svc::DebugException_BreakPoint;
params[1] = far;
params[2] = ams::svc::BreakPointType_HardwareData;
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}
break;
case EsrEc_SErrorInterrupt:
{
params[0] = ams::svc::DebugException_MemorySystemError;
params[1] = far;
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}
break;
case EsrEc_InstructionAbortEl0:
{
params[0] = ams::svc::DebugException_InstructionAbort;
params[1] = far;
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}
break;
case EsrEc_DataAbortEl0:
default:
{
params[0] = ams::svc::DebugException_DataAbort;
params[1] = far;
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}
break;
}
/* Process the debug event. */
Result result = KDebug::OnDebugEvent(ams::svc::DebugEvent_Exception, params, util::size(params));
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/* If we should stop processing the exception, do so. */
if (svc::ResultStopProcessingException::Includes(result)) {
return;
}
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#if defined(MESOSPHERE_ENABLE_HARDWARE_SINGLE_STEP)
{
if (ec != EsrEc_SoftwareStepEl0) {
/* If the exception wasn't single-step, print details. */
MESOSPHERE_EXCEPTION_LOG("Exception occurred. ");
{
/* Print the current thread's registers. */
KDebug::PrintRegister();
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/* Print a backtrace. */
KDebug::PrintBacktrace();
}
} else {
/* If the exception was single-step and we have no debug object, we should just return. */
if (AMS_UNLIKELY(!cur_process.IsAttachedToDebugger())) {
return;
}
}
}
#else
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{
/* Print that an exception occurred. */
MESOSPHERE_EXCEPTION_LOG("Exception occurred. ");
{
/* Print the current thread's registers. */
KDebug::PrintRegister();
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/* Print a backtrace. */
KDebug::PrintBacktrace();
}
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}
#endif
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/* If the SVC is handled, handle it. */
if (!svc::ResultNotHandled::Includes(result)) {
/* If we successfully enter jit debug, stop processing the exception. */
if (cur_process.EnterJitDebug(ams::svc::DebugEvent_Exception, static_cast<ams::svc::DebugException>(params[0]), params[1], params[2])) {
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return;
}
}
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}
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/* Exit the current process. */
cur_process.Exit();
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}
}
/* NOTE: This function is called from ASM. */
void FpuContextSwitchHandler() {
KThreadContext::FpuContextSwitchHandler(GetCurrentThreadPointer());
}
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/* NOTE: This function is called from ASM. */
void ReturnFromException(Result user_result) {
/* Get the current thread. */
KThread *cur_thread = GetCurrentThreadPointer();
/* Get the current exception context. */
KExceptionContext *e_ctx = GetExceptionContext(cur_thread);
/* Get the current process. */
KProcess &cur_process = GetCurrentProcess();
/* Read the exception info that userland put in tls. */
union {
ams::svc::aarch64::ExceptionInfo info64;
ams::svc::aarch32::ExceptionInfo info32;
} info = {};
const bool is_aarch64 = (e_ctx->psr & 0x10) == 0;
if (is_aarch64) {
/* We're 64-bit. */
info.info64 = static_cast<const ams::svc::aarch64::ProcessLocalRegion *>(cur_process.GetProcessLocalRegionHeapAddress())->exception_info;
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} else {
/* We're 32-bit. */
info.info32 = static_cast<const ams::svc::aarch32::ProcessLocalRegion *>(cur_process.GetProcessLocalRegionHeapAddress())->exception_info;
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}
/* Try to leave the user exception. */
if (cur_process.LeaveUserException()) {
/* Process that we're leaving a usermode exception on the current thread. */
GetCurrentThread().OnLeaveUsermodeException();
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/* Copy the user context to the thread context. */
if (is_aarch64) {
for (size_t i = 0; i < util::size(info.info64.r); ++i) {
e_ctx->x[i] = info.info64.r[i];
}
e_ctx->x[30] = info.info64.lr;
e_ctx->sp = info.info64.sp;
e_ctx->pc = info.info64.pc;
e_ctx->psr = (info.info64.pstate & cpu::El0Aarch64PsrMask) | (e_ctx->psr & ~cpu::El0Aarch64PsrMask);
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} else {
for (size_t i = 0; i < util::size(info.info32.r); ++i) {
e_ctx->x[i] = info.info32.r[i];
}
e_ctx->x[14] = info.info32.lr;
e_ctx->x[13] = info.info32.sp;
e_ctx->pc = info.info32.pc;
e_ctx->psr = (info.info32.status_64.pstate & cpu::El0Aarch32PsrMask) | (e_ctx->psr & ~cpu::El0Aarch32PsrMask);
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}
/* Note that PC was adjusted. */
e_ctx->write = 1;
if (R_SUCCEEDED(user_result)) {
/* If result handling succeeded, just restore the context. */
svc::RestoreContext(reinterpret_cast<uintptr_t>(e_ctx));
} else {
/* Restore the debug params for the exception. */
uintptr_t far, esr, data;
GetCurrentThread().RestoreDebugParams(std::addressof(far), std::addressof(esr), std::addressof(data));
/* Collect additional information based on the ec. */
uintptr_t params[3] = {};
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switch ((esr >> 26) & 0x3F) {
case EsrEc_Unknown:
case EsrEc_IllegalExecution:
case EsrEc_BkptInstruction:
case EsrEc_BrkInstruction:
{
params[0] = ams::svc::DebugException_UndefinedInstruction;
params[1] = far;
params[2] = data;
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}
break;
case EsrEc_PcAlignmentFault:
case EsrEc_SpAlignmentFault:
{
params[0] = ams::svc::DebugException_AlignmentFault;
params[1] = far;
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}
break;
case EsrEc_Svc32:
case EsrEc_Svc64:
{
params[0] = ams::svc::DebugException_UndefinedSystemCall;
params[1] = far;
params[2] = (esr & 0xFF);
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}
break;
case EsrEc_SErrorInterrupt:
{
params[0] = ams::svc::DebugException_MemorySystemError;
params[1] = far;
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}
break;
case EsrEc_InstructionAbortEl0:
{
params[0] = ams::svc::DebugException_InstructionAbort;
params[1] = far;
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}
break;
case EsrEc_DataAbortEl0:
default:
{
params[0] = ams::svc::DebugException_DataAbort;
params[1] = far;
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}
break;
}
/* Process the debug event. */
Result result = KDebug::OnDebugEvent(ams::svc::DebugEvent_Exception, params, util::size(params));
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/* If the SVC is handled, handle it. */
if (!svc::ResultNotHandled::Includes(result)) {
/* If we should stop processing the exception, restore. */
if (svc::ResultStopProcessingException::Includes(result)) {
svc::RestoreContext(reinterpret_cast<uintptr_t>(e_ctx));
}
/* If we successfully enter jit debug, restore. */
if (cur_process.EnterJitDebug(ams::svc::DebugEvent_Exception, static_cast<ams::svc::DebugException>(params[0]), params[1], params[2])) {
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svc::RestoreContext(reinterpret_cast<uintptr_t>(e_ctx));
}
}
/* Otherwise, if result debug was returned, restore. */
if (svc::ResultDebug::Includes(result)) {
svc::RestoreContext(reinterpret_cast<uintptr_t>(e_ctx));
}
}
}
/* Print that an exception occurred. */
MESOSPHERE_EXCEPTION_LOG("Exception occurred. ");
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/* Exit the current process. */
GetCurrentProcess().Exit();
}
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/* NOTE: This function is called from ASM. */
void HandleException(KExceptionContext *context) {
MESOSPHERE_ASSERT(!KInterruptManager::AreInterruptsEnabled());
/* Retrieve information about the exception. */
const u64 esr = cpu::GetEsrEl1();
const u64 afsr0 = cpu::GetAfsr0El1();
const u64 afsr1 = cpu::GetAfsr1El1();
u64 far = 0;
u32 data = 0;
/* Collect far and data based on the ec. */
switch ((esr >> 26) & 0x3F) {
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case EsrEc_Unknown:
case EsrEc_IllegalExecution:
case EsrEc_BkptInstruction:
case EsrEc_BrkInstruction:
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far = context->pc;
data = GetInstructionData(context, esr);
break;
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case EsrEc_Svc32:
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if (context->psr & 0x20) {
/* Thumb mode. */
context->pc -= 2;
} else {
/* ARM mode. */
context->pc -= 4;
}
far = context->pc;
break;
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case EsrEc_Svc64:
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context->pc -= 4;
far = context->pc;
break;
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case EsrEc_BreakPointEl0:
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far = context->pc;
break;
default:
far = cpu::GetFarEl1();
break;
}
/* Note that we're in an exception handler. */
GetCurrentThread().SetInExceptionHandler();
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/* Verify that spsr's M is allowable (EL0t). */
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{
const bool is_user_mode = (context->psr & 0xF) == 0;
if (is_user_mode) {
/* If the user disable count is set, we may need to pin the current thread. */
if (GetCurrentThread().GetUserDisableCount() != 0 && GetCurrentProcess().GetPinnedThread(GetCurrentCoreId()) == nullptr) {
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KScopedSchedulerLock lk;
/* Pin the current thread. */
GetCurrentProcess().PinCurrentThread();
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/* Set the interrupt flag for the thread. */
GetCurrentThread().SetInterruptFlag();
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}
/* Enable interrupts while we process the usermode exception. */
{
KScopedInterruptEnable ei;
/* Terminate the thread, if we should. */
if (GetCurrentThread().IsTerminationRequested()) {
GetCurrentThread().Exit();
}
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HandleUserException(context, esr, far, afsr0, afsr1, data);
}
} else {
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const s32 core_id = GetCurrentCoreId();
MESOSPHERE_LOG("%d: Unhandled Exception in Supervisor Mode\n", core_id);
if (GetCurrentProcessPointer() != nullptr) {
MESOSPHERE_LOG("%d: Current Process = %s\n", core_id, GetCurrentProcess().GetName());
}
for (size_t i = 0; i < 31; i++) {
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MESOSPHERE_LOG("%d: X[%02zu] = %016lx\n", core_id, i, context->x[i]);
}
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MESOSPHERE_LOG("%d: PC = %016lx\n", core_id, context->pc);
MESOSPHERE_LOG("%d: SP = %016lx\n", core_id, context->sp);
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MESOSPHERE_PANIC("Unhandled Exception in Supervisor Mode\n");
}
MESOSPHERE_ASSERT(!KInterruptManager::AreInterruptsEnabled());
/* Handle any DPC requests. */
while (GetCurrentThread().HasDpc()) {
KDpcManager::HandleDpc();
}
}
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/* Note that we're no longer in an exception handler. */
GetCurrentThread().ClearInExceptionHandler();
}
}