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ladybird/Kernel/Arch/x86/common/Processor.cpp
Lenny Maiorani c6acf64558 Kernel: Change static constexpr variables to constexpr where possible 
Function-local `static constexpr` variables can be `constexpr`. This
can reduce memory consumption, binary size, and offer additional
compiler optimizations.

These changes result in a stripped x86_64 kernel binary size reduction
of 592 bytes.
2022-02-09 21:04:51 +00:00

1395 lines
48 KiB
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/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2022, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/BuiltinWrappers.h>
#include <AK/Format.h>
#include <AK/StdLibExtras.h>
#include <AK/StringBuilder.h>
#include <AK/Types.h>
#include <Kernel/Interrupts/APIC.h>
#include <Kernel/Process.h>
#include <Kernel/Scheduler.h>
#include <Kernel/Sections.h>
#include <Kernel/StdLib.h>
#include <Kernel/Thread.h>
#include <Kernel/Arch/Processor.h>
#include <Kernel/Arch/ScopedCritical.h>
#include <Kernel/Arch/x86/CPUID.h>
#include <Kernel/Arch/x86/InterruptDisabler.h>
#include <Kernel/Arch/x86/Interrupts.h>
#include <Kernel/Arch/x86/MSR.h>
#include <Kernel/Arch/x86/ProcessorInfo.h>
#include <Kernel/Arch/x86/SafeMem.h>
#include <Kernel/Arch/x86/TrapFrame.h>
#include <Kernel/Memory/PageDirectory.h>
#include <Kernel/Memory/ScopedAddressSpaceSwitcher.h>
namespace Kernel {
READONLY_AFTER_INIT FPUState Processor::s_clean_fpu_state;
READONLY_AFTER_INIT static ProcessorContainer s_processors {};
READONLY_AFTER_INIT Atomic<u32> Processor::g_total_processors;
READONLY_AFTER_INIT static volatile bool s_smp_enabled;
static Atomic<ProcessorMessage*> s_message_pool;
Atomic<u32> Processor::s_idle_cpu_mask { 0 };
// The compiler can't see the calls to these functions inside assembly.
// Declare them, to avoid dead code warnings.
extern "C" void context_first_init(Thread* from_thread, Thread* to_thread, TrapFrame* trap) __attribute__((used));
extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread) __attribute__((used));
extern "C" FlatPtr do_init_context(Thread* thread, u32 flags) __attribute__((used));
extern "C" void syscall_entry();
bool Processor::is_smp_enabled()
{
return s_smp_enabled;
}
UNMAP_AFTER_INIT static void sse_init()
{
write_cr0((read_cr0() & 0xfffffffbu) | 0x2);
write_cr4(read_cr4() | 0x600);
}
void exit_kernel_thread(void)
{
Thread::current()->exit();
}
UNMAP_AFTER_INIT void Processor::cpu_detect()
{
// NOTE: This is called during Processor::early_initialize, we cannot
// safely log at this point because we don't have kmalloc
// initialized yet!
auto set_feature =
[&](CPUFeature f) {
m_features = static_cast<CPUFeature>(static_cast<u32>(m_features) | static_cast<u32>(f));
};
m_features = static_cast<CPUFeature>(0);
CPUID processor_info(0x1);
if (processor_info.edx() & (1 << 4))
set_feature(CPUFeature::TSC);
if (processor_info.edx() & (1 << 6))
set_feature(CPUFeature::PAE);
if (processor_info.edx() & (1 << 13))
set_feature(CPUFeature::PGE);
if (processor_info.edx() & (1 << 23))
set_feature(CPUFeature::MMX);
if (processor_info.edx() & (1 << 24))
set_feature(CPUFeature::FXSR);
if (processor_info.edx() & (1 << 25))
set_feature(CPUFeature::SSE);
if (processor_info.edx() & (1 << 26))
set_feature(CPUFeature::SSE2);
if (processor_info.ecx() & (1 << 0))
set_feature(CPUFeature::SSE3);
if (processor_info.ecx() & (1 << 9))
set_feature(CPUFeature::SSSE3);
if (processor_info.ecx() & (1 << 19))
set_feature(CPUFeature::SSE4_1);
if (processor_info.ecx() & (1 << 20))
set_feature(CPUFeature::SSE4_2);
if (processor_info.ecx() & (1 << 26))
set_feature(CPUFeature::XSAVE);
if (processor_info.ecx() & (1 << 28))
set_feature(CPUFeature::AVX);
if (processor_info.ecx() & (1 << 30))
set_feature(CPUFeature::RDRAND);
if (processor_info.ecx() & (1u << 31))
set_feature(CPUFeature::HYPERVISOR);
if (processor_info.edx() & (1 << 11)) {
u32 stepping = processor_info.eax() & 0xf;
u32 model = (processor_info.eax() >> 4) & 0xf;
u32 family = (processor_info.eax() >> 8) & 0xf;
if (!(family == 6 && model < 3 && stepping < 3))
set_feature(CPUFeature::SEP);
if ((family == 6 && model >= 3) || (family == 0xf && model >= 0xe))
set_feature(CPUFeature::CONSTANT_TSC);
}
if (processor_info.edx() & (1 << 16))
set_feature(CPUFeature::PAT);
u32 max_extended_leaf = CPUID(0x80000000).eax();
if (max_extended_leaf >= 0x80000001) {
CPUID extended_processor_info(0x80000001);
if (extended_processor_info.edx() & (1 << 20))
set_feature(CPUFeature::NX);
if (extended_processor_info.edx() & (1 << 27))
set_feature(CPUFeature::RDTSCP);
if (extended_processor_info.edx() & (1 << 29))
set_feature(CPUFeature::LM);
if (extended_processor_info.edx() & (1 << 11)) {
// Only available in 64 bit mode
set_feature(CPUFeature::SYSCALL);
}
}
if (max_extended_leaf >= 0x80000007) {
CPUID cpuid(0x80000007);
if (cpuid.edx() & (1 << 8)) {
set_feature(CPUFeature::CONSTANT_TSC);
set_feature(CPUFeature::NONSTOP_TSC);
}
}
if (max_extended_leaf >= 0x80000008) {
// CPUID.80000008H:EAX[7:0] reports the physical-address width supported by the processor.
CPUID cpuid(0x80000008);
m_physical_address_bit_width = cpuid.eax() & 0xff;
// CPUID.80000008H:EAX[15:8] reports the linear-address width supported by the processor.
m_virtual_address_bit_width = (cpuid.eax() >> 8) & 0xff;
} else {
// For processors that do not support CPUID function 80000008H, the width is generally 36 if CPUID.01H:EDX.PAE [bit 6] = 1 and 32 otherwise.
m_physical_address_bit_width = has_feature(CPUFeature::PAE) ? 36 : 32;
// Processors that do not support CPUID function 80000008H, support a linear-address width of 32.
m_virtual_address_bit_width = 32;
}
CPUID extended_features(0x7);
if (extended_features.ebx() & (1 << 20))
set_feature(CPUFeature::SMAP);
if (extended_features.ebx() & (1 << 7))
set_feature(CPUFeature::SMEP);
if (extended_features.ecx() & (1 << 2))
set_feature(CPUFeature::UMIP);
if (extended_features.ebx() & (1 << 18))
set_feature(CPUFeature::RDSEED);
}
UNMAP_AFTER_INIT void Processor::cpu_setup()
{
// NOTE: This is called during Processor::early_initialize, we cannot
// safely log at this point because we don't have kmalloc
// initialized yet!
cpu_detect();
if (has_feature(CPUFeature::SSE)) {
// enter_thread_context() assumes that if a x86 CPU supports SSE then it also supports FXSR.
// SSE support without FXSR is an extremely unlikely scenario, so let's be pragmatic about it.
VERIFY(has_feature(CPUFeature::FXSR));
sse_init();
}
write_cr0(read_cr0() | 0x00010000);
if (has_feature(CPUFeature::PGE)) {
// Turn on CR4.PGE so the CPU will respect the G bit in page tables.
write_cr4(read_cr4() | 0x80);
}
if (has_feature(CPUFeature::NX)) {
// Turn on IA32_EFER.NXE
MSR ia32_efer(MSR_IA32_EFER);
ia32_efer.set(ia32_efer.get() | 0x800);
}
if (has_feature(CPUFeature::PAT)) {
MSR ia32_pat(MSR_IA32_PAT);
// Set PA4 to Write Comine. This allows us to
// use this mode by only setting the bit in the PTE
// and leaving all other bits in the upper levels unset,
// which maps to setting bit 3 of the index, resulting
// in the index value 0 or 4.
u64 pat = ia32_pat.get() & ~(0x7ull << 32);
pat |= 0x1ull << 32; // set WC mode for PA4
ia32_pat.set(pat);
}
if (has_feature(CPUFeature::SMEP)) {
// Turn on CR4.SMEP
write_cr4(read_cr4() | 0x100000);
}
if (has_feature(CPUFeature::SMAP)) {
// Turn on CR4.SMAP
write_cr4(read_cr4() | 0x200000);
}
if (has_feature(CPUFeature::UMIP)) {
write_cr4(read_cr4() | 0x800);
}
if (has_feature(CPUFeature::TSC)) {
write_cr4(read_cr4() | 0x4);
}
if (has_feature(CPUFeature::XSAVE)) {
// Turn on CR4.OSXSAVE
write_cr4(read_cr4() | 0x40000);
// According to the Intel manual: "After reset, all bits (except bit 0) in XCR0 are cleared to zero; XCR0[0] is set to 1."
// Sadly we can't trust this, for example VirtualBox starts with bits 0-4 set, so let's do it ourselves.
write_xcr0(0x1);
if (has_feature(CPUFeature::AVX)) {
// Turn on SSE, AVX and x87 flags
write_xcr0(read_xcr0() | 0x7);
}
}
#if ARCH(X86_64)
// x86_64 processors must support the syscall feature.
VERIFY(has_feature(CPUFeature::SYSCALL));
MSR efer_msr(MSR_EFER);
efer_msr.set(efer_msr.get() | 1u);
// Write code and stack selectors to the STAR MSR. The first value stored in bits 63:48 controls the sysret CS (value + 0x10) and SS (value + 0x8),
// and the value stored in bits 47:32 controls the syscall CS (value) and SS (value + 0x8).
u64 star = 0;
star |= 0x13ul << 48u;
star |= 0x08ul << 32u;
MSR star_msr(MSR_STAR);
star_msr.set(star);
// Write the syscall entry point to the LSTAR MSR.
MSR lstar_msr(MSR_LSTAR);
lstar_msr.set(reinterpret_cast<u64>(&syscall_entry));
// Write the SFMASK MSR. This MSR controls which bits of rflags are masked when a syscall instruction is executed -
// if a bit is set in sfmask, the corresponding bit in rflags is cleared. The value set here clears most of rflags,
// but keeps the reserved and virtualization bits intact. The userspace rflags value is saved in r11 by syscall.
constexpr u64 rflags_mask = 0x257fd5u;
MSR sfmask_msr(MSR_SFMASK);
sfmask_msr.set(rflags_mask);
#endif
}
NonnullOwnPtr<KString> Processor::features_string() const
{
StringBuilder builder;
auto feature_to_str =
[](CPUFeature f) -> StringView {
switch (f) {
case CPUFeature::NX:
return "nx"sv;
case CPUFeature::PAE:
return "pae"sv;
case CPUFeature::PGE:
return "pge"sv;
case CPUFeature::RDRAND:
return "rdrand"sv;
case CPUFeature::RDSEED:
return "rdseed"sv;
case CPUFeature::SMAP:
return "smap"sv;
case CPUFeature::SMEP:
return "smep"sv;
case CPUFeature::SSE:
return "sse"sv;
case CPUFeature::TSC:
return "tsc"sv;
case CPUFeature::RDTSCP:
return "rdtscp"sv;
case CPUFeature::CONSTANT_TSC:
return "constant_tsc"sv;
case CPUFeature::NONSTOP_TSC:
return "nonstop_tsc"sv;
case CPUFeature::UMIP:
return "umip"sv;
case CPUFeature::SEP:
return "sep"sv;
case CPUFeature::SYSCALL:
return "syscall"sv;
case CPUFeature::MMX:
return "mmx"sv;
case CPUFeature::FXSR:
return "fxsr"sv;
case CPUFeature::SSE2:
return "sse2"sv;
case CPUFeature::SSE3:
return "sse3"sv;
case CPUFeature::SSSE3:
return "ssse3"sv;
case CPUFeature::SSE4_1:
return "sse4.1"sv;
case CPUFeature::SSE4_2:
return "sse4.2"sv;
case CPUFeature::XSAVE:
return "xsave"sv;
case CPUFeature::AVX:
return "avx"sv;
case CPUFeature::LM:
return "lm"sv;
case CPUFeature::HYPERVISOR:
return "hypervisor"sv;
// no default statement here intentionally so that we get
// a warning if a new feature is forgotten to be added here
case CPUFeature::PAT:
return "pat"sv;
}
// Shouldn't ever happen
return "???"sv;
};
bool first = true;
for (u32 flag = 1; flag != 0; flag <<= 1) {
if ((static_cast<u32>(m_features) & flag) != 0) {
if (first)
first = false;
else
MUST(builder.try_append(' '));
auto str = feature_to_str(static_cast<CPUFeature>(flag));
MUST(builder.try_append(str));
}
}
return KString::must_create(builder.string_view());
}
UNMAP_AFTER_INIT void Processor::early_initialize(u32 cpu)
{
m_self = this;
m_cpu = cpu;
m_in_irq = 0;
m_in_critical = 0;
m_invoke_scheduler_async = false;
m_scheduler_initialized = false;
m_in_scheduler = true;
m_message_queue = nullptr;
m_idle_thread = nullptr;
m_current_thread = nullptr;
m_info = nullptr;
m_halt_requested = false;
if (cpu == 0) {
s_smp_enabled = false;
g_total_processors.store(1u, AK::MemoryOrder::memory_order_release);
} else {
g_total_processors.fetch_add(1u, AK::MemoryOrder::memory_order_acq_rel);
}
deferred_call_pool_init();
cpu_setup();
gdt_init();
VERIFY(is_initialized()); // sanity check
VERIFY(&current() == this); // sanity check
}
UNMAP_AFTER_INIT void Processor::initialize(u32 cpu)
{
VERIFY(m_self == this);
VERIFY(&current() == this); // sanity check
dmesgln("CPU[{}]: Supported features: {}", current_id(), features_string());
if (!has_feature(CPUFeature::RDRAND))
dmesgln("CPU[{}]: No RDRAND support detected, randomness will be poor", current_id());
dmesgln("CPU[{}]: Physical address bit width: {}", current_id(), m_physical_address_bit_width);
dmesgln("CPU[{}]: Virtual address bit width: {}", current_id(), m_virtual_address_bit_width);
if (cpu == 0)
idt_init();
else
flush_idt();
if (cpu == 0) {
VERIFY((FlatPtr(&s_clean_fpu_state) & 0xF) == 0);
asm volatile("fninit");
if (has_feature(CPUFeature::FXSR))
asm volatile("fxsave %0"
: "=m"(s_clean_fpu_state));
else
asm volatile("fnsave %0"
: "=m"(s_clean_fpu_state));
if (has_feature(CPUFeature::HYPERVISOR))
detect_hypervisor();
}
m_info = new ProcessorInfo(*this);
{
// We need to prevent races between APs starting up at the same time
VERIFY(cpu < s_processors.size());
s_processors[cpu] = this;
}
}
UNMAP_AFTER_INIT void Processor::detect_hypervisor()
{
CPUID hypervisor_leaf_range(0x40000000);
// Get signature of hypervisor.
alignas(sizeof(u32)) char hypervisor_signature_buffer[13];
*reinterpret_cast<u32*>(hypervisor_signature_buffer) = hypervisor_leaf_range.ebx();
*reinterpret_cast<u32*>(hypervisor_signature_buffer + 4) = hypervisor_leaf_range.ecx();
*reinterpret_cast<u32*>(hypervisor_signature_buffer + 8) = hypervisor_leaf_range.edx();
hypervisor_signature_buffer[12] = '\0';
StringView hypervisor_signature(hypervisor_signature_buffer);
dmesgln("CPU[{}]: CPUID hypervisor signature '{}' ({:#x} {:#x} {:#x}), max leaf {:#x}", current_id(), hypervisor_signature, hypervisor_leaf_range.ebx(), hypervisor_leaf_range.ecx(), hypervisor_leaf_range.edx(), hypervisor_leaf_range.eax());
if (hypervisor_signature == "Microsoft Hv"sv)
detect_hypervisor_hyperv(hypervisor_leaf_range);
}
UNMAP_AFTER_INIT void Processor::detect_hypervisor_hyperv(CPUID const& hypervisor_leaf_range)
{
if (hypervisor_leaf_range.eax() < 0x40000001)
return;
CPUID hypervisor_interface(0x40000001);
// Get signature of hypervisor interface.
alignas(sizeof(u32)) char interface_signature_buffer[5];
*reinterpret_cast<u32*>(interface_signature_buffer) = hypervisor_interface.eax();
interface_signature_buffer[4] = '\0';
StringView hyperv_interface_signature(interface_signature_buffer);
dmesgln("CPU[{}]: Hyper-V interface signature '{}' ({:#x})", current_id(), hyperv_interface_signature, hypervisor_interface.eax());
if (hypervisor_leaf_range.eax() < 0x40000001)
return;
CPUID hypervisor_sysid(0x40000002);
dmesgln("CPU[{}]: Hyper-V system identity {}.{}, build number {}", current_id(), hypervisor_sysid.ebx() >> 16, hypervisor_sysid.ebx() & 0xFFFF, hypervisor_sysid.eax());
if (hypervisor_leaf_range.eax() < 0x40000005 || hyperv_interface_signature != "Hv#1"sv)
return;
dmesgln("CPU[{}]: Hyper-V hypervisor detected", current_id());
// TODO: Actually do something with Hyper-V.
}
void Processor::write_raw_gdt_entry(u16 selector, u32 low, u32 high)
{
u16 i = (selector & 0xfffc) >> 3;
u32 prev_gdt_length = m_gdt_length;
if (i >= m_gdt_length) {
m_gdt_length = i + 1;
VERIFY(m_gdt_length <= sizeof(m_gdt) / sizeof(m_gdt[0]));
m_gdtr.limit = (m_gdt_length + 1) * 8 - 1;
}
m_gdt[i].low = low;
m_gdt[i].high = high;
// clear selectors we may have skipped
for (auto j = prev_gdt_length; j < i; ++j) {
m_gdt[j].low = 0;
m_gdt[j].high = 0;
}
}
void Processor::write_gdt_entry(u16 selector, Descriptor& descriptor)
{
write_raw_gdt_entry(selector, descriptor.low, descriptor.high);
}
Descriptor& Processor::get_gdt_entry(u16 selector)
{
u16 i = (selector & 0xfffc) >> 3;
return *(Descriptor*)(&m_gdt[i]);
}
void Processor::flush_gdt()
{
m_gdtr.address = m_gdt;
m_gdtr.limit = (m_gdt_length * 8) - 1;
asm volatile("lgdt %0" ::"m"(m_gdtr)
: "memory");
}
const DescriptorTablePointer& Processor::get_gdtr()
{
return m_gdtr;
}
ErrorOr<Vector<FlatPtr, 32>> Processor::capture_stack_trace(Thread& thread, size_t max_frames)
{
FlatPtr frame_ptr = 0, ip = 0;
Vector<FlatPtr, 32> stack_trace;
auto walk_stack = [&](FlatPtr stack_ptr) -> ErrorOr<void> {
constexpr size_t max_stack_frames = 4096;
bool is_walking_userspace_stack = false;
TRY(stack_trace.try_append(ip));
size_t count = 1;
while (stack_ptr && stack_trace.size() < max_stack_frames) {
FlatPtr retaddr;
count++;
if (max_frames != 0 && count > max_frames)
break;
if (!Memory::is_user_address(VirtualAddress { stack_ptr })) {
if (is_walking_userspace_stack) {
dbgln("SHENANIGANS! Userspace stack points back into kernel memory");
break;
}
} else {
is_walking_userspace_stack = true;
}
if (Memory::is_user_range(VirtualAddress(stack_ptr), sizeof(FlatPtr) * 2)) {
if (copy_from_user(&retaddr, &((FlatPtr*)stack_ptr)[1]).is_error() || !retaddr)
break;
TRY(stack_trace.try_append(retaddr));
if (copy_from_user(&stack_ptr, (FlatPtr*)stack_ptr).is_error())
break;
} else {
void* fault_at;
if (!safe_memcpy(&retaddr, &((FlatPtr*)stack_ptr)[1], sizeof(FlatPtr), fault_at) || !retaddr)
break;
TRY(stack_trace.try_append(retaddr));
if (!safe_memcpy(&stack_ptr, (FlatPtr*)stack_ptr, sizeof(FlatPtr), fault_at))
break;
}
}
return {};
};
auto capture_current_thread = [&]() {
frame_ptr = (FlatPtr)__builtin_frame_address(0);
ip = (FlatPtr)__builtin_return_address(0);
return walk_stack(frame_ptr);
};
// Since the thread may be running on another processor, there
// is a chance a context switch may happen while we're trying
// to get it. It also won't be entirely accurate and merely
// reflect the status at the last context switch.
SpinlockLocker lock(g_scheduler_lock);
if (&thread == Processor::current_thread()) {
VERIFY(thread.state() == Thread::State::Running);
// Leave the scheduler lock. If we trigger page faults we may
// need to be preempted. Since this is our own thread it won't
// cause any problems as the stack won't change below this frame.
lock.unlock();
TRY(capture_current_thread());
} else if (thread.is_active()) {
VERIFY(thread.cpu() != Processor::current_id());
// If this is the case, the thread is currently running
// on another processor. We can't trust the kernel stack as
// it may be changing at any time. We need to probably send
// an IPI to that processor, have it walk the stack and wait
// until it returns the data back to us
auto& proc = Processor::current();
ErrorOr<void> result;
smp_unicast(
thread.cpu(),
[&]() {
dbgln("CPU[{}] getting stack for cpu #{}", Processor::current_id(), proc.id());
ScopedAddressSpaceSwitcher switcher(thread.process());
VERIFY(&Processor::current() != &proc);
VERIFY(&thread == Processor::current_thread());
// NOTE: Because the other processor is still holding the
// scheduler lock while waiting for this callback to finish,
// the current thread on the target processor cannot change
// TODO: What to do about page faults here? We might deadlock
// because the other processor is still holding the
// scheduler lock...
result = capture_current_thread();
},
false);
TRY(result);
} else {
switch (thread.state()) {
case Thread::State::Running:
VERIFY_NOT_REACHED(); // should have been handled above
case Thread::State::Runnable:
case Thread::State::Stopped:
case Thread::State::Blocked:
case Thread::State::Dying:
case Thread::State::Dead: {
// We need to retrieve ebp from what was last pushed to the kernel
// stack. Before switching out of that thread, it switch_context
// pushed the callee-saved registers, and the last of them happens
// to be ebp.
ScopedAddressSpaceSwitcher switcher(thread.process());
auto& regs = thread.regs();
auto* stack_top = reinterpret_cast<FlatPtr*>(regs.sp());
if (Memory::is_user_range(VirtualAddress(stack_top), sizeof(FlatPtr))) {
if (copy_from_user(&frame_ptr, &((FlatPtr*)stack_top)[0]).is_error())
frame_ptr = 0;
} else {
void* fault_at;
if (!safe_memcpy(&frame_ptr, &((FlatPtr*)stack_top)[0], sizeof(FlatPtr), fault_at))
frame_ptr = 0;
}
ip = regs.ip();
// TODO: We need to leave the scheduler lock here, but we also
// need to prevent the target thread from being run while
// we walk the stack
lock.unlock();
TRY(walk_stack(frame_ptr));
break;
}
default:
dbgln("Cannot capture stack trace for thread {} in state {}", thread, thread.state_string());
break;
}
}
return stack_trace;
}
ProcessorContainer& Processor::processors()
{
return s_processors;
}
Processor& Processor::by_id(u32 id)
{
return *s_processors[id];
}
void Processor::enter_trap(TrapFrame& trap, bool raise_irq)
{
VERIFY_INTERRUPTS_DISABLED();
VERIFY(&Processor::current() == this);
trap.prev_irq_level = m_in_irq;
if (raise_irq)
m_in_irq++;
auto* current_thread = Processor::current_thread();
if (current_thread) {
auto& current_trap = current_thread->current_trap();
trap.next_trap = current_trap;
current_trap = &trap;
// The cs register of this trap tells us where we will return back to
auto new_previous_mode = ((trap.regs->cs & 3) != 0) ? Thread::PreviousMode::UserMode : Thread::PreviousMode::KernelMode;
if (current_thread->set_previous_mode(new_previous_mode) && trap.prev_irq_level == 0) {
current_thread->update_time_scheduled(Scheduler::current_time(), new_previous_mode == Thread::PreviousMode::KernelMode, false);
}
} else {
trap.next_trap = nullptr;
}
}
void Processor::exit_trap(TrapFrame& trap)
{
VERIFY_INTERRUPTS_DISABLED();
VERIFY(&Processor::current() == this);
// Temporarily enter a critical section. This is to prevent critical
// sections entered and left within e.g. smp_process_pending_messages
// to trigger a context switch while we're executing this function
// See the comment at the end of the function why we don't use
// ScopedCritical here.
m_in_critical = m_in_critical + 1;
VERIFY(m_in_irq >= trap.prev_irq_level);
m_in_irq = trap.prev_irq_level;
if (s_smp_enabled)
smp_process_pending_messages();
// Process the deferred call queue. Among other things, this ensures
// that any pending thread unblocks happen before we enter the scheduler.
deferred_call_execute_pending();
auto* current_thread = Processor::current_thread();
if (current_thread) {
auto& current_trap = current_thread->current_trap();
current_trap = trap.next_trap;
Thread::PreviousMode new_previous_mode;
if (current_trap) {
VERIFY(current_trap->regs);
// If we have another higher level trap then we probably returned
// from an interrupt or irq handler. The cs register of the
// new/higher level trap tells us what the mode prior to it was
new_previous_mode = ((current_trap->regs->cs & 3) != 0) ? Thread::PreviousMode::UserMode : Thread::PreviousMode::KernelMode;
} else {
// If we don't have a higher level trap then we're back in user mode.
// Which means that the previous mode prior to being back in user mode was kernel mode
new_previous_mode = Thread::PreviousMode::KernelMode;
}
if (current_thread->set_previous_mode(new_previous_mode))
current_thread->update_time_scheduled(Scheduler::current_time(), true, false);
}
VERIFY_INTERRUPTS_DISABLED();
// Leave the critical section without actually enabling interrupts.
// We don't want context switches to happen until we're explicitly
// triggering a switch in check_invoke_scheduler.
m_in_critical = m_in_critical - 1;
if (!m_in_irq && !m_in_critical)
check_invoke_scheduler();
}
void Processor::check_invoke_scheduler()
{
InterruptDisabler disabler;
VERIFY(!m_in_irq);
VERIFY(!m_in_critical);
VERIFY(&Processor::current() == this);
if (m_invoke_scheduler_async && m_scheduler_initialized) {
m_invoke_scheduler_async = false;
Scheduler::invoke_async();
}
}
void Processor::flush_tlb_local(VirtualAddress vaddr, size_t page_count)
{
auto ptr = vaddr.as_ptr();
while (page_count > 0) {
// clang-format off
asm volatile("invlpg %0"
:
: "m"(*ptr)
: "memory");
// clang-format on
ptr += PAGE_SIZE;
page_count--;
}
}
void Processor::flush_tlb(Memory::PageDirectory const* page_directory, VirtualAddress vaddr, size_t page_count)
{
if (s_smp_enabled && (!Memory::is_user_address(vaddr) || Process::current().thread_count() > 1))
smp_broadcast_flush_tlb(page_directory, vaddr, page_count);
else
flush_tlb_local(vaddr, page_count);
}
void Processor::smp_return_to_pool(ProcessorMessage& msg)
{
ProcessorMessage* next = nullptr;
for (;;) {
msg.next = next;
if (s_message_pool.compare_exchange_strong(next, &msg, AK::MemoryOrder::memory_order_acq_rel))
break;
Processor::pause();
}
}
ProcessorMessage& Processor::smp_get_from_pool()
{
ProcessorMessage* msg;
// The assumption is that messages are never removed from the pool!
for (;;) {
msg = s_message_pool.load(AK::MemoryOrder::memory_order_consume);
if (!msg) {
if (!Processor::current().smp_process_pending_messages()) {
Processor::pause();
}
continue;
}
// If another processor were to use this message in the meanwhile,
// "msg" is still valid (because it never gets freed). We'd detect
// this because the expected value "msg" and pool would
// no longer match, and the compare_exchange will fail. But accessing
// "msg->next" is always safe here.
if (s_message_pool.compare_exchange_strong(msg, msg->next, AK::MemoryOrder::memory_order_acq_rel)) {
// We successfully "popped" this available message
break;
}
}
VERIFY(msg != nullptr);
return *msg;
}
u32 Processor::smp_wake_n_idle_processors(u32 wake_count)
{
VERIFY_INTERRUPTS_DISABLED();
VERIFY(wake_count > 0);
if (!s_smp_enabled)
return 0;
// Wake at most N - 1 processors
if (wake_count >= Processor::count()) {
wake_count = Processor::count() - 1;
VERIFY(wake_count > 0);
}
u32 current_id = Processor::current_id();
u32 did_wake_count = 0;
auto& apic = APIC::the();
while (did_wake_count < wake_count) {
// Try to get a set of idle CPUs and flip them to busy
u32 idle_mask = s_idle_cpu_mask.load(AK::MemoryOrder::memory_order_relaxed) & ~(1u << current_id);
u32 idle_count = popcount(idle_mask);
if (idle_count == 0)
break; // No (more) idle processor available
u32 found_mask = 0;
for (u32 i = 0; i < idle_count; i++) {
u32 cpu = bit_scan_forward(idle_mask) - 1;
idle_mask &= ~(1u << cpu);
found_mask |= 1u << cpu;
}
idle_mask = s_idle_cpu_mask.fetch_and(~found_mask, AK::MemoryOrder::memory_order_acq_rel) & found_mask;
if (idle_mask == 0)
continue; // All of them were flipped to busy, try again
idle_count = popcount(idle_mask);
for (u32 i = 0; i < idle_count; i++) {
u32 cpu = bit_scan_forward(idle_mask) - 1;
idle_mask &= ~(1u << cpu);
// Send an IPI to that CPU to wake it up. There is a possibility
// someone else woke it up as well, or that it woke up due to
// a timer interrupt. But we tried hard to avoid this...
apic.send_ipi(cpu);
did_wake_count++;
}
}
return did_wake_count;
}
UNMAP_AFTER_INIT void Processor::smp_enable()
{
size_t msg_pool_size = Processor::count() * 100u;
size_t msg_entries_cnt = Processor::count();
auto msgs = new ProcessorMessage[msg_pool_size];
auto msg_entries = new ProcessorMessageEntry[msg_pool_size * msg_entries_cnt];
size_t msg_entry_i = 0;
for (size_t i = 0; i < msg_pool_size; i++, msg_entry_i += msg_entries_cnt) {
auto& msg = msgs[i];
msg.next = i < msg_pool_size - 1 ? &msgs[i + 1] : nullptr;
msg.per_proc_entries = &msg_entries[msg_entry_i];
for (size_t k = 0; k < msg_entries_cnt; k++)
msg_entries[msg_entry_i + k].msg = &msg;
}
s_message_pool.store(&msgs[0], AK::MemoryOrder::memory_order_release);
// Start sending IPI messages
s_smp_enabled = true;
}
void Processor::smp_cleanup_message(ProcessorMessage& msg)
{
switch (msg.type) {
case ProcessorMessage::Callback:
msg.callback_value().~Function();
break;
default:
break;
}
}
bool Processor::smp_process_pending_messages()
{
VERIFY(s_smp_enabled);
bool did_process = false;
enter_critical();
if (auto pending_msgs = m_message_queue.exchange(nullptr, AK::MemoryOrder::memory_order_acq_rel)) {
// We pulled the stack of pending messages in LIFO order, so we need to reverse the list first
auto reverse_list =
[](ProcessorMessageEntry* list) -> ProcessorMessageEntry* {
ProcessorMessageEntry* rev_list = nullptr;
while (list) {
auto next = list->next;
list->next = rev_list;
rev_list = list;
list = next;
}
return rev_list;
};
pending_msgs = reverse_list(pending_msgs);
// now process in the right order
ProcessorMessageEntry* next_msg;
for (auto cur_msg = pending_msgs; cur_msg; cur_msg = next_msg) {
next_msg = cur_msg->next;
auto msg = cur_msg->msg;
dbgln_if(SMP_DEBUG, "SMP[{}]: Processing message {}", current_id(), VirtualAddress(msg));
switch (msg->type) {
case ProcessorMessage::Callback:
msg->invoke_callback();
break;
case ProcessorMessage::FlushTlb:
if (Memory::is_user_address(VirtualAddress(msg->flush_tlb.ptr))) {
// We assume that we don't cross into kernel land!
VERIFY(Memory::is_user_range(VirtualAddress(msg->flush_tlb.ptr), msg->flush_tlb.page_count * PAGE_SIZE));
if (read_cr3() != msg->flush_tlb.page_directory->cr3()) {
// This processor isn't using this page directory right now, we can ignore this request
dbgln_if(SMP_DEBUG, "SMP[{}]: No need to flush {} pages at {}", current_id(), msg->flush_tlb.page_count, VirtualAddress(msg->flush_tlb.ptr));
break;
}
}
flush_tlb_local(VirtualAddress(msg->flush_tlb.ptr), msg->flush_tlb.page_count);
break;
}
bool is_async = msg->async; // Need to cache this value *before* dropping the ref count!
auto prev_refs = msg->refs.fetch_sub(1u, AK::MemoryOrder::memory_order_acq_rel);
VERIFY(prev_refs != 0);
if (prev_refs == 1) {
// All processors handled this. If this is an async message,
// we need to clean it up and return it to the pool
if (is_async) {
smp_cleanup_message(*msg);
smp_return_to_pool(*msg);
}
}
if (m_halt_requested.load(AK::MemoryOrder::memory_order_relaxed))
halt_this();
}
did_process = true;
} else if (m_halt_requested.load(AK::MemoryOrder::memory_order_relaxed)) {
halt_this();
}
leave_critical();
return did_process;
}
bool Processor::smp_enqueue_message(ProcessorMessage& msg)
{
// Note that it's quite possible that the other processor may pop
// the queue at any given time. We rely on the fact that the messages
// are pooled and never get freed!
auto& msg_entry = msg.per_proc_entries[id()];
VERIFY(msg_entry.msg == &msg);
ProcessorMessageEntry* next = nullptr;
for (;;) {
msg_entry.next = next;
if (m_message_queue.compare_exchange_strong(next, &msg_entry, AK::MemoryOrder::memory_order_acq_rel))
break;
Processor::pause();
}
// If the enqueued message was the only message in the queue when posted,
// we return true. This is used by callers when deciding whether to generate an IPI.
return next == nullptr;
}
void Processor::smp_broadcast_message(ProcessorMessage& msg)
{
auto& current_processor = Processor::current();
dbgln_if(SMP_DEBUG, "SMP[{}]: Broadcast message {} to cpus: {} processor: {}", current_processor.id(), VirtualAddress(&msg), count(), VirtualAddress(&current_processor));
msg.refs.store(count() - 1, AK::MemoryOrder::memory_order_release);
VERIFY(msg.refs > 0);
bool need_broadcast = false;
for_each(
[&](Processor& proc) {
if (&proc != &current_processor) {
if (proc.smp_enqueue_message(msg))
need_broadcast = true;
}
});
// Now trigger an IPI on all other APs (unless all targets already had messages queued)
if (need_broadcast)
APIC::the().broadcast_ipi();
}
void Processor::smp_broadcast_wait_sync(ProcessorMessage& msg)
{
auto& cur_proc = Processor::current();
VERIFY(!msg.async);
// If synchronous then we must cleanup and return the message back
// to the pool. Otherwise, the last processor to complete it will return it
while (msg.refs.load(AK::MemoryOrder::memory_order_consume) != 0) {
Processor::pause();
// We need to process any messages that may have been sent to
// us while we're waiting. This also checks if another processor
// may have requested us to halt.
cur_proc.smp_process_pending_messages();
}
smp_cleanup_message(msg);
smp_return_to_pool(msg);
}
void Processor::smp_unicast_message(u32 cpu, ProcessorMessage& msg, bool async)
{
auto& current_processor = Processor::current();
VERIFY(cpu != current_processor.id());
auto& target_processor = processors()[cpu];
msg.async = async;
dbgln_if(SMP_DEBUG, "SMP[{}]: Send message {} to cpu #{} processor: {}", current_processor.id(), VirtualAddress(&msg), cpu, VirtualAddress(&target_processor));
msg.refs.store(1u, AK::MemoryOrder::memory_order_release);
if (target_processor->smp_enqueue_message(msg)) {
APIC::the().send_ipi(cpu);
}
if (!async) {
// If synchronous then we must cleanup and return the message back
// to the pool. Otherwise, the last processor to complete it will return it
while (msg.refs.load(AK::MemoryOrder::memory_order_consume) != 0) {
Processor::pause();
// We need to process any messages that may have been sent to
// us while we're waiting. This also checks if another processor
// may have requested us to halt.
current_processor.smp_process_pending_messages();
}
smp_cleanup_message(msg);
smp_return_to_pool(msg);
}
}
void Processor::smp_unicast(u32 cpu, Function<void()> callback, bool async)
{
auto& msg = smp_get_from_pool();
msg.type = ProcessorMessage::Callback;
new (msg.callback_storage) ProcessorMessage::CallbackFunction(move(callback));
smp_unicast_message(cpu, msg, async);
}
void Processor::smp_broadcast_flush_tlb(Memory::PageDirectory const* page_directory, VirtualAddress vaddr, size_t page_count)
{
auto& msg = smp_get_from_pool();
msg.async = false;
msg.type = ProcessorMessage::FlushTlb;
msg.flush_tlb.page_directory = page_directory;
msg.flush_tlb.ptr = vaddr.as_ptr();
msg.flush_tlb.page_count = page_count;
smp_broadcast_message(msg);
// While the other processors handle this request, we'll flush ours
flush_tlb_local(vaddr, page_count);
// Now wait until everybody is done as well
smp_broadcast_wait_sync(msg);
}
void Processor::smp_broadcast_halt()
{
// We don't want to use a message, because this could have been triggered
// by being out of memory and we might not be able to get a message
for_each(
[&](Processor& proc) {
proc.m_halt_requested.store(true, AK::MemoryOrder::memory_order_release);
});
// Now trigger an IPI on all other APs
APIC::the().broadcast_ipi();
}
void Processor::Processor::halt()
{
if (s_smp_enabled)
smp_broadcast_halt();
halt_this();
}
UNMAP_AFTER_INIT void Processor::deferred_call_pool_init()
{
size_t pool_count = sizeof(m_deferred_call_pool) / sizeof(m_deferred_call_pool[0]);
for (size_t i = 0; i < pool_count; i++) {
auto& entry = m_deferred_call_pool[i];
entry.next = i < pool_count - 1 ? &m_deferred_call_pool[i + 1] : nullptr;
new (entry.handler_storage) DeferredCallEntry::HandlerFunction;
entry.was_allocated = false;
}
m_pending_deferred_calls = nullptr;
m_free_deferred_call_pool_entry = &m_deferred_call_pool[0];
}
void Processor::deferred_call_return_to_pool(DeferredCallEntry* entry)
{
VERIFY(m_in_critical);
VERIFY(!entry->was_allocated);
entry->handler_value() = {};
entry->next = m_free_deferred_call_pool_entry;
m_free_deferred_call_pool_entry = entry;
}
DeferredCallEntry* Processor::deferred_call_get_free()
{
VERIFY(m_in_critical);
if (m_free_deferred_call_pool_entry) {
// Fast path, we have an entry in our pool
auto* entry = m_free_deferred_call_pool_entry;
m_free_deferred_call_pool_entry = entry->next;
VERIFY(!entry->was_allocated);
return entry;
}
auto* entry = new DeferredCallEntry;
new (entry->handler_storage) DeferredCallEntry::HandlerFunction;
entry->was_allocated = true;
return entry;
}
void Processor::deferred_call_execute_pending()
{
VERIFY(m_in_critical);
if (!m_pending_deferred_calls)
return;
auto* pending_list = m_pending_deferred_calls;
m_pending_deferred_calls = nullptr;
// We pulled the stack of pending deferred calls in LIFO order, so we need to reverse the list first
auto reverse_list =
[](DeferredCallEntry* list) -> DeferredCallEntry* {
DeferredCallEntry* rev_list = nullptr;
while (list) {
auto next = list->next;
list->next = rev_list;
rev_list = list;
list = next;
}
return rev_list;
};
pending_list = reverse_list(pending_list);
do {
pending_list->invoke_handler();
// Return the entry back to the pool, or free it
auto* next = pending_list->next;
if (pending_list->was_allocated) {
pending_list->handler_value().~Function();
delete pending_list;
} else
deferred_call_return_to_pool(pending_list);
pending_list = next;
} while (pending_list);
}
void Processor::deferred_call_queue_entry(DeferredCallEntry* entry)
{
VERIFY(m_in_critical);
entry->next = m_pending_deferred_calls;
m_pending_deferred_calls = entry;
}
void Processor::deferred_call_queue(Function<void()> callback)
{
// NOTE: If we are called outside of a critical section and outside
// of an irq handler, the function will be executed before we return!
ScopedCritical critical;
auto& cur_proc = Processor::current();
auto* entry = cur_proc.deferred_call_get_free();
entry->handler_value() = move(callback);
cur_proc.deferred_call_queue_entry(entry);
}
UNMAP_AFTER_INIT void Processor::gdt_init()
{
m_gdt_length = 0;
m_gdtr.address = nullptr;
m_gdtr.limit = 0;
write_raw_gdt_entry(0x0000, 0x00000000, 0x00000000);
#if ARCH(I386)
write_raw_gdt_entry(GDT_SELECTOR_CODE0, 0x0000ffff, 0x00cf9a00); // code0
write_raw_gdt_entry(GDT_SELECTOR_DATA0, 0x0000ffff, 0x00cf9200); // data0
write_raw_gdt_entry(GDT_SELECTOR_CODE3, 0x0000ffff, 0x00cffa00); // code3
write_raw_gdt_entry(GDT_SELECTOR_DATA3, 0x0000ffff, 0x00cff200); // data3
#else
write_raw_gdt_entry(GDT_SELECTOR_CODE0, 0x0000ffff, 0x00af9a00); // code0
write_raw_gdt_entry(GDT_SELECTOR_DATA0, 0x0000ffff, 0x00af9200); // data0
write_raw_gdt_entry(GDT_SELECTOR_DATA3, 0x0000ffff, 0x008ff200); // data3
write_raw_gdt_entry(GDT_SELECTOR_CODE3, 0x0000ffff, 0x00affa00); // code3
#endif
#if ARCH(I386)
Descriptor tls_descriptor {};
tls_descriptor.low = tls_descriptor.high = 0;
tls_descriptor.dpl = 3;
tls_descriptor.segment_present = 1;
tls_descriptor.granularity = 0;
tls_descriptor.operation_size64 = 0;
tls_descriptor.operation_size32 = 1;
tls_descriptor.descriptor_type = 1;
tls_descriptor.type = 2;
write_gdt_entry(GDT_SELECTOR_TLS, tls_descriptor); // tls3
Descriptor gs_descriptor {};
gs_descriptor.set_base(VirtualAddress { this });
gs_descriptor.set_limit(sizeof(Processor) - 1);
gs_descriptor.dpl = 0;
gs_descriptor.segment_present = 1;
gs_descriptor.granularity = 0;
gs_descriptor.operation_size64 = 0;
gs_descriptor.operation_size32 = 1;
gs_descriptor.descriptor_type = 1;
gs_descriptor.type = 2;
write_gdt_entry(GDT_SELECTOR_PROC, gs_descriptor); // gs0
#endif
Descriptor tss_descriptor {};
tss_descriptor.set_base(VirtualAddress { (size_t)&m_tss & 0xffffffff });
tss_descriptor.set_limit(sizeof(TSS) - 1);
tss_descriptor.dpl = 0;
tss_descriptor.segment_present = 1;
tss_descriptor.granularity = 0;
tss_descriptor.operation_size64 = 0;
tss_descriptor.operation_size32 = 1;
tss_descriptor.descriptor_type = 0;
tss_descriptor.type = Descriptor::SystemType::AvailableTSS;
write_gdt_entry(GDT_SELECTOR_TSS, tss_descriptor); // tss
#if ARCH(X86_64)
Descriptor tss_descriptor_part2 {};
tss_descriptor_part2.low = (size_t)&m_tss >> 32;
write_gdt_entry(GDT_SELECTOR_TSS_PART2, tss_descriptor_part2);
#endif
flush_gdt();
load_task_register(GDT_SELECTOR_TSS);
#if ARCH(X86_64)
MSR gs_base(MSR_GS_BASE);
gs_base.set((u64)this);
#else
asm volatile(
"mov %%ax, %%ds\n"
"mov %%ax, %%es\n"
"mov %%ax, %%fs\n"
"mov %%ax, %%ss\n" ::"a"(GDT_SELECTOR_DATA0)
: "memory");
set_gs(GDT_SELECTOR_PROC);
#endif
#if ARCH(I386)
// Make sure CS points to the kernel code descriptor.
// clang-format off
asm volatile(
"ljmpl $" __STRINGIFY(GDT_SELECTOR_CODE0) ", $sanity\n"
"sanity:\n");
// clang-format on
#endif
}
extern "C" void context_first_init([[maybe_unused]] Thread* from_thread, [[maybe_unused]] Thread* to_thread, [[maybe_unused]] TrapFrame* trap)
{
VERIFY(!are_interrupts_enabled());
VERIFY(is_kernel_mode());
dbgln_if(CONTEXT_SWITCH_DEBUG, "switch_context <-- from {} {} to {} {} (context_first_init)", VirtualAddress(from_thread), *from_thread, VirtualAddress(to_thread), *to_thread);
VERIFY(to_thread == Thread::current());
Scheduler::enter_current(*from_thread);
auto in_critical = to_thread->saved_critical();
VERIFY(in_critical > 0);
Processor::restore_in_critical(in_critical);
// Since we got here and don't have Scheduler::context_switch in the
// call stack (because this is the first time we switched into this
// context), we need to notify the scheduler so that it can release
// the scheduler lock. We don't want to enable interrupts at this point
// as we're still in the middle of a context switch. Doing so could
// trigger a context switch within a context switch, leading to a crash.
FlatPtr flags = trap->regs->flags();
Scheduler::leave_on_first_switch(flags & ~0x200);
}
extern "C" void enter_thread_context(Thread* from_thread, Thread* to_thread)
{
VERIFY(from_thread == to_thread || from_thread->state() != Thread::State::Running);
VERIFY(to_thread->state() == Thread::State::Running);
bool has_fxsr = Processor::current().has_feature(CPUFeature::FXSR);
Processor::set_current_thread(*to_thread);
auto& from_regs = from_thread->regs();
auto& to_regs = to_thread->regs();
// NOTE: IOPL should never be non-zero in any situation, so let's panic immediately
// instead of carrying on with elevated I/O privileges.
VERIFY(get_iopl_from_eflags(to_regs.flags()) == 0);
if (has_fxsr)
asm volatile("fxsave %0"
: "=m"(from_thread->fpu_state()));
else
asm volatile("fnsave %0"
: "=m"(from_thread->fpu_state()));
#if ARCH(I386)
from_regs.fs = get_fs();
from_regs.gs = get_gs();
set_fs(to_regs.fs);
set_gs(to_regs.gs);
#endif
if (from_thread->process().is_traced())
read_debug_registers_into(from_thread->debug_register_state());
if (to_thread->process().is_traced()) {
write_debug_registers_from(to_thread->debug_register_state());
} else {
clear_debug_registers();
}
auto& processor = Processor::current();
#if ARCH(I386)
auto& tls_descriptor = processor.get_gdt_entry(GDT_SELECTOR_TLS);
tls_descriptor.set_base(to_thread->thread_specific_data());
tls_descriptor.set_limit(to_thread->thread_specific_region_size());
#else
MSR fs_base_msr(MSR_FS_BASE);
fs_base_msr.set(to_thread->thread_specific_data().get());
#endif
if (from_regs.cr3 != to_regs.cr3)
write_cr3(to_regs.cr3);
to_thread->set_cpu(processor.id());
auto in_critical = to_thread->saved_critical();
VERIFY(in_critical > 0);
Processor::restore_in_critical(in_critical);
if (has_fxsr)
asm volatile("fxrstor %0" ::"m"(to_thread->fpu_state()));
else
asm volatile("frstor %0" ::"m"(to_thread->fpu_state()));
}
extern "C" FlatPtr do_init_context(Thread* thread, u32 flags)
{
VERIFY_INTERRUPTS_DISABLED();
thread->regs().set_flags(flags);
return Processor::current().init_context(*thread, true);
}
void Processor::assume_context(Thread& thread, FlatPtr flags)
{
dbgln_if(CONTEXT_SWITCH_DEBUG, "Assume context for thread {} {}", VirtualAddress(&thread), thread);
VERIFY_INTERRUPTS_DISABLED();
Scheduler::prepare_after_exec();
// in_critical() should be 2 here. The critical section in Process::exec
// and then the scheduler lock
VERIFY(Processor::in_critical() == 2);
do_assume_context(&thread, flags);
VERIFY_NOT_REACHED();
}
u64 Processor::time_spent_idle() const
{
return m_idle_thread->time_in_user() + m_idle_thread->time_in_kernel();
}
}
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