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essence-os/arch/x86_32/kernel.cpp

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// TODO Support for systems without MMX/SSE.
// TODO Support for systems without an APIC.
#ifndef IMPLEMENTATION
struct MMArchVAS {
// NOTE Must be first in the structure. See ProcessorSetAddressSpace and ArchSwitchContext.
uintptr_t cr3;
// Each process has a 32-bit address space.
// That's 2^20 pages.
// That's 2^10 L1 page tables. 2^7 bytes of bitset.
// Tracking of the committed L1 tables is done in l1Commit.
#define L1_COMMIT_SIZE_BYTES (1 << 7)
uint8_t l1Commit[L1_COMMIT_SIZE_BYTES];
size_t pageTablesCommitted;
size_t pageTablesActive;
// TODO Consider core/kernel mutex consistency? I think it's fine, but...
KMutex mutex; // Acquire to modify the page tables.
};
#define MM_KERNEL_SPACE_START (0xC4000000)
#define MM_KERNEL_SPACE_SIZE (0xE0000000 - 0xC4000000)
#define MM_MODULES_START (0xE0000000)
#define MM_MODULES_SIZE (0xE6000000 - 0xE0000000)
#define MM_CORE_REGIONS_START (0xE6000000)
#define MM_CORE_REGIONS_COUNT ((0xE7000000 - 0xE6000000) / sizeof(MMRegion))
#define MM_CORE_SPACE_START (0xE7000000)
#define MM_CORE_SPACE_SIZE (0xEC000000 - 0xE7000000)
#define LOW_MEMORY_MAP_START (0xEC000000)
#define LOW_MEMORY_LIMIT (0x00400000) // The first 4MB - 4KB is mapped here; the last 4KB map to the local APIC.
#define LOCAL_APIC_BASE (0xEC3FF000)
#define ArchCheckBundleHeader() (header.mapAddress >= 0xC0000000ULL || header.mapAddress < 0x1000 || fileSize > 0x10000000ULL)
#define ArchCheckELFHeader() (header->virtualAddress >= 0xC0000000ULL || header->virtualAddress < 0x1000 || header->segmentSize > 0x10000000ULL)
#define K_ARCH_STACK_GROWS_DOWN
#define K_ARCH_NAME "x86_32"
#endif
#ifdef IMPLEMENTATION
// Recursive page table mapping in slot 0x1FF.
#define PAGE_TABLE_L2 ((volatile uint32_t *) 0xFFFFF000)
#define PAGE_TABLE_L1 ((volatile uint32_t *) 0xFFC00000)
#define ENTRIES_PER_PAGE_TABLE (1024)
#define ENTRIES_PER_PAGE_TABLE_BITS (10)
struct InterruptContext {
uint32_t cr8, cr2, ds;
uint8_t fxsave[512 + 16];
uint32_t ebp, edi, esi, edx, ecx, ebx, eax;
uint32_t fromRing0, irq, errorCode;
uint32_t eip, cs, flags, esp, ss;
// Note that when ring 0 is interrupted the order is different:
// esp, ss, irq, errorCode, eip, cs, flags.
// However we fix it before and after interrupts in InterruptHandler.
};
volatile uintptr_t tlbShootdownVirtualAddress;
volatile size_t tlbShootdownPageCount;
volatile size_t tlbShootdownProcessorsRemaining;
#include <arch/x86_pc.h>
#include <drivers/acpi.cpp>
#include <arch/x86_pc.cpp>
InterruptContext *ArchInitialiseThread(uintptr_t kernelStack, uintptr_t kernelStackSize,
Thread *thread, uintptr_t startAddress, uintptr_t argument1,
uintptr_t argument2, bool userland, uintptr_t stack, uintptr_t userStackSize) {
InterruptContext *context = ((InterruptContext *) (kernelStack + kernelStackSize - 12)) - 1;
thread->kernelStack = kernelStack + kernelStackSize - 12;
*((uintptr_t *) (kernelStack + kernelStackSize - 12)) = (uintptr_t) KThreadTerminate;
*((uintptr_t *) (kernelStack + kernelStackSize - 8)) = argument1;
*((uintptr_t *) (kernelStack + kernelStackSize - 4)) = argument2;
context->fxsave[32] = 0x80;
context->fxsave[33] = 0x1F;
if (userland) {
context->cs = 0x1B;
context->ds = 0x23;
context->ss = 0x23;
} else {
context->cs = 0x08;
context->ds = 0x10;
context->ss = 0x10;
context->fromRing0 = true;
}
context->flags = 1 << 9; // Interrupt flag
context->eip = startAddress;
context->esp = stack + userStackSize;
return context;
}
void TLBShootdownCallback() {
uintptr_t page = tlbShootdownVirtualAddress;
// TODO How should this be determined?
#define INVALIDATE_ALL_PAGES_THRESHOLD (1024)
if (tlbShootdownPageCount > INVALIDATE_ALL_PAGES_THRESHOLD) {
ProcessorInvalidateAllPages();
} else {
for (uintptr_t i = 0; i < tlbShootdownPageCount; i++, page += K_PAGE_SIZE) {
ProcessorInvalidatePage(page);
}
}
}
void MMArchInvalidatePages(uintptr_t virtualAddressStart, uintptr_t pageCount) {
KSpinlockAcquire(&ipiLock);
tlbShootdownVirtualAddress = virtualAddressStart;
tlbShootdownPageCount = pageCount;
tlbShootdownProcessorsRemaining = KGetCPUCount();
if (tlbShootdownProcessorsRemaining > 1) {
size_t ignored = ProcessorSendIPI(TLB_SHOOTDOWN_IPI);
__sync_fetch_and_sub(&tlbShootdownProcessorsRemaining, ignored);
while (tlbShootdownProcessorsRemaining);
}
TLBShootdownCallback();
KSpinlockRelease(&ipiLock);
}
bool MMArchIsBufferInUserRange(uintptr_t baseAddress, size_t byteCount) {
// TODO.
KernelPanic("Unimplemented!\n");
return false;
}
bool MMArchSafeCopy(uintptr_t destinationAddress, uintptr_t sourceAddress, size_t byteCount) {
// TODO.
KernelPanic("Unimplemented!\n");
return false;
}
bool MMArchCommitPageTables(MMSpace *space, MMRegion *region) {
KMutexAssertLocked(&space->reserveMutex);
MMArchVAS *data = &space->data;
uintptr_t base = region->baseAddress - (space == coreMMSpace ? MM_CORE_SPACE_START : 0);
uintptr_t end = base + (region->pageCount << K_PAGE_BITS);
uintptr_t needed = 0;
for (uintptr_t i = base; i < end; i += 1L << (K_PAGE_BITS + ENTRIES_PER_PAGE_TABLE_BITS * 1)) {
uintptr_t indexL2 = i >> (K_PAGE_BITS + ENTRIES_PER_PAGE_TABLE_BITS * 1);
if (!(data->l1Commit[indexL2 >> 3] & (1 << (indexL2 & 7)))) needed++;
i = indexL2 << (K_PAGE_BITS + ENTRIES_PER_PAGE_TABLE_BITS * 1);
}
if (needed) {
if (!MMCommit(needed * K_PAGE_SIZE, true)) {
return false;
}
data->pageTablesCommitted += needed;
}
for (uintptr_t i = base; i < end; i += 1L << (K_PAGE_BITS + ENTRIES_PER_PAGE_TABLE_BITS * 1)) {
uintptr_t indexL2 = i >> (K_PAGE_BITS + ENTRIES_PER_PAGE_TABLE_BITS * 1);
data->l1Commit[indexL2 >> 3] |= (1 << (indexL2 & 7));
i = indexL2 << (K_PAGE_BITS + ENTRIES_PER_PAGE_TABLE_BITS * 1);
}
return true;
}
bool MMArchInitialiseUserSpace(MMSpace *space, MMRegion *firstRegion) {
// TODO.
KernelPanic("Unimplemented!\n");
return false;
}
void MMArchFreeVAS(MMSpace *space) {
// TODO.
KernelPanic("Unimplemented!\n");
}
void MMArchFinalizeVAS(MMSpace *space) {
// TODO.
KernelPanic("Unimplemented!\n");
}
void ArchStartupApplicationProcessors() {
// TODO.
}
bool MMArchHandlePageFault(uintptr_t address, uint32_t flags) {
address &= ~(K_PAGE_SIZE - 1);
bool forSupervisor = flags & MM_HANDLE_PAGE_FAULT_FOR_SUPERVISOR;
if (!ProcessorAreInterruptsEnabled()) {
KernelPanic("MMArchHandlePageFault - Page fault with interrupts disabled.\n");
}
if (address >= MM_CORE_REGIONS_START && address < MM_CORE_REGIONS_START + MM_CORE_REGIONS_COUNT * sizeof(MMRegion) && forSupervisor) {
// This is where coreMMSpace stores its regions.
// Allocate physical memory and map it.
MMArchMapPage(kernelMMSpace, MMPhysicalAllocate(MM_PHYSICAL_ALLOCATE_ZEROED), address, MM_MAP_PAGE_COMMIT_TABLES_NOW);
return true;
} else if (address >= MM_CORE_SPACE_START && address < MM_CORE_SPACE_START + MM_CORE_SPACE_SIZE && forSupervisor) {
return MMHandlePageFault(coreMMSpace, address, flags);
} else if (address >= MM_KERNEL_SPACE_START && address < MM_KERNEL_SPACE_START + MM_KERNEL_SPACE_SIZE && forSupervisor) {
return MMHandlePageFault(kernelMMSpace, address, flags);
} else if (address >= MM_MODULES_START && address < MM_MODULES_START + MM_MODULES_SIZE && forSupervisor) {
return MMHandlePageFault(kernelMMSpace, address, flags);
} else if (address >= K_PAGE_SIZE) {
Thread *thread = GetCurrentThread();
return MMHandlePageFault(thread->temporaryAddressSpace ?: thread->process->vmm, address, flags);
}
return false;
}
void ContextSanityCheck(InterruptContext *context) {
if (context->cs > 0x100 || context->ds > 0x100 || context->ss > 0x100
|| (context->eip < 0xC0000000 && context->cs == 0x08)) {
KernelPanic("ContextSanityCheck - Corrupt context (%x/%x/%x/%x/%x/%x)\n",
context, context->cs, context->ds, context->ss, context->eip, context->esp);
}
}
extern "C" void InterruptHandler(InterruptContext *context) {
if (context->fromRing0) {
uint32_t esp = context->irq;
uint32_t ss = context->errorCode;
context->irq = context->eip;
context->errorCode = context->cs;
context->eip = context->flags;
context->cs = context->esp;
context->flags = context->ss;
context->esp = esp;
context->ss = ss;
}
CPULocalStorage *local = GetLocalStorage();
if (scheduler.panic && context->irq != 2) {
goto end;
}
if (context->irq < 0x20) {
// Processor exception.
ProcessorEnableInterrupts();
if ((context->cs & 3) == 0) {
bool handled = false;
if (context->irq == 0x0E && (~context->errorCode & (1 << 3))) {
if (MMArchHandlePageFault(context->cr2, MM_HANDLE_PAGE_FAULT_FOR_SUPERVISOR
| ((context->errorCode & 2) ? MM_HANDLE_PAGE_FAULT_WRITE : 0))) {
handled = true;
}
}
if (!handled) {
KernelPanic("Unresolvable processor exception encountered in supervisor mode.\n%z\nEIP = %x (CPU %d)\nX86 error codes: [err] %x, [cr2] %x\n"
"Stack: [esp] %x, [ebp] %x\nRegisters: [eax] %x, [ebx] %x, [esi] %x, [edi] %x.\nThread ID = %d\n",
exceptionInformation[context->irq], context->eip, local ? local->processorID : -1, context->errorCode, context->cr2,
context->esp, context->ebp, context->eax, context->ebx, context->esi, context->edi,
local && local->currentThread ? local->currentThread->id : -1);
}
} else {
// TODO User exceptions.
}
} else if (context->irq == 0xFF) {
// Spurious interrupt (APIC), ignore.
} else if (context->irq >= 0x20 && context->irq < 0x30) {
// Spurious interrupt (PIC), ignore.
} else if (context->irq == TLB_SHOOTDOWN_IPI) {
TLBShootdownCallback();
if (!tlbShootdownProcessorsRemaining) KernelPanic("InterruptHandler - tlbShootdownProcessorsRemaining is 0.\n");
__sync_fetch_and_sub(&tlbShootdownProcessorsRemaining, 1);
} else if (context->irq == TIMER_INTERRUPT) {
if (local && scheduler.started && local->schedulerReady) {
scheduler.Yield(context);
}
} else if (context->irq >= INTERRUPT_VECTOR_MSI_START && context->irq < INTERRUPT_VECTOR_MSI_START + INTERRUPT_VECTOR_MSI_COUNT && local) {
KSpinlockAcquire(&irqHandlersLock);
MSIHandler handler = msiHandlers[context->irq - INTERRUPT_VECTOR_MSI_START];
KSpinlockRelease(&irqHandlersLock);
local->irqSwitchThread = false;
if (!handler.callback) {
KernelLog(LOG_ERROR, "Arch", "unexpected MSI", "Unexpected MSI vector %X (no handler).\n", context->irq);
} else {
handler.callback(context->irq - INTERRUPT_VECTOR_MSI_START, handler.context);
}
if (local->irqSwitchThread && scheduler.started && local->schedulerReady) {
scheduler.Yield(context); // LapicEndOfInterrupt is called in PostContextSwitch.
}
LapicEndOfInterrupt();
} else if (context->irq >= IRQ_BASE && context->irq < IRQ_BASE + 0x20 && local) {
// See InterruptHandler in arch/x86_64/kernel.cpp for a discussion of what this is doing.
local->irqSwitchThread = false;
local->inIRQ = true;
uintptr_t line = context->irq - IRQ_BASE;
KSpinlockAcquire(&irqHandlersLock);
for (uintptr_t i = 0; i < sizeof(irqHandlers) / sizeof(irqHandlers[0]); i++) {
IRQHandler handler = irqHandlers[i];
if (!handler.callback) continue;
if (handler.line == -1) {
if (line != 9 && line != 10 && line != 11) {
continue;
} else {
uint8_t mappedLine = pciIRQLines[handler.pciDevice->slot][handler.pciDevice->interruptPin - 1];
if (mappedLine && line != mappedLine) {
continue;
}
}
} else {
if ((uintptr_t) handler.line != line) {
continue;
}
}
KSpinlockRelease(&irqHandlersLock);
handler.callback(context->irq - IRQ_BASE, handler.context);
KSpinlockAcquire(&irqHandlersLock);
}
KSpinlockRelease(&irqHandlersLock);
local->inIRQ = false;
if (local->irqSwitchThread && scheduler.started && local->schedulerReady) {
scheduler.Yield(context);
}
LapicEndOfInterrupt();
}
if (context->irq >= 0x30 && context->irq != 0xFF) {
LapicEndOfInterrupt();
}
end:;
ContextSanityCheck(context);
if (context->fromRing0) {
uint32_t irq = context->esp;
uint32_t errorCode = context->ss;
context->ss = context->flags;
context->esp = context->cs;
context->flags = context->eip;
context->cs = context->errorCode;
context->eip = context->irq;
context->irq = irq;
context->errorCode = errorCode;
}
}
#include <kernel/terminal.cpp>
#endif
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