mirror of
https://github.com/LadybirdBrowser/ladybird.git
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2d045d2a64
sys$fork() now clones all writable regions with per-page COW bits. The pages are then mapped read-only and we handle a PF by COWing the pages. This is quite delightful. Obviously there's lots of work to do still, and it needs better data structures, but the general concept works.
447 lines
11 KiB
C++
447 lines
11 KiB
C++
#include "types.h"
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#include "kmalloc.h"
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#include "VGA.h"
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#include "i386.h"
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#include "Assertions.h"
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#include "Process.h"
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#include "MemoryManager.h"
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#include "IRQHandler.h"
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#include "PIC.h"
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struct DescriptorTablePointer {
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WORD size;
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void* address;
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} PACKED;
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static DescriptorTablePointer s_idtr;
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static DescriptorTablePointer s_gdtr;
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static Descriptor* s_idt;
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static Descriptor* s_gdt;
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static IRQHandler** s_irqHandler;
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static Vector<word, KmallocEternalAllocator>* s_gdt_freelist;
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static WORD s_gdtLength;
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word gdt_alloc_entry()
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{
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ASSERT(s_gdt_freelist);
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ASSERT(!s_gdt_freelist->isEmpty());
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return s_gdt_freelist->takeLast();
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}
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void gdt_free_entry(word entry)
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{
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s_gdt_freelist->append(entry);
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}
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extern "C" void handleIRQ();
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extern "C" void commonIRQEntry();
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asm(
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".globl commonIRQEntry\n"
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"commonIRQEntry: \n"
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" pusha\n"
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" pushw %ds\n"
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" pushw %es\n"
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" pushw %ss\n"
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" pushw %ss\n"
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" popw %ds\n"
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" popw %es\n"
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" call handleIRQ\n"
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" popw %es\n"
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" popw %ds\n"
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" popa\n"
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" iret\n"
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);
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#define EH_ENTRY(ec) \
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extern "C" void exception_ ## ec ## _handler(RegisterDumpWithExceptionCode&); \
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extern "C" void exception_ ## ec ## _entry(); \
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asm( \
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".globl exception_" # ec "_entry\n" \
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"exception_" # ec "_entry: \n" \
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" pusha\n" \
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" pushw %ds\n" \
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" pushw %es\n" \
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" pushw %fs\n" \
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" pushw %gs\n" \
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" pushw %ss\n" \
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" pushw %ss\n" \
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" pushw %ss\n" \
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" pushw %ss\n" \
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" pushw %ss\n" \
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" popw %ds\n" \
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" popw %es\n" \
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" popw %fs\n" \
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" popw %gs\n" \
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" mov %esp, %eax\n" \
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" call exception_" # ec "_handler\n" \
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" popw %gs\n" \
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" popw %gs\n" \
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" popw %fs\n" \
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" popw %es\n" \
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" popw %ds\n" \
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" popa\n" \
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" add $0x4, %esp\n" \
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" iret\n" \
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);
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#define EH_ENTRY_NO_CODE(ec) \
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extern "C" void exception_ ## ec ## _handler(RegisterDump&); \
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extern "C" void exception_ ## ec ## _entry(); \
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asm( \
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".globl exception_" # ec "_entry\n" \
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"exception_" # ec "_entry: \n" \
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" pusha\n" \
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" pushw %ds\n" \
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" pushw %es\n" \
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" pushw %fs\n" \
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" pushw %gs\n" \
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" pushw %ss\n" \
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" pushw %ss\n" \
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" pushw %ss\n" \
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" pushw %ss\n" \
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" pushw %ss\n" \
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" popw %ds\n" \
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" popw %es\n" \
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" popw %fs\n" \
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" popw %gs\n" \
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" mov %esp, %eax\n" \
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" call exception_" # ec "_handler\n" \
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" popw %gs\n" \
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" popw %gs\n" \
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" popw %fs\n" \
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" popw %es\n" \
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" popw %ds\n" \
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" popa\n" \
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" iret\n" \
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);
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// 6: Invalid Opcode
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EH_ENTRY_NO_CODE(6);
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void exception_6_handler(RegisterDump& regs)
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{
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kprintf("%s invalid opcode: %u(%s)\n", current->isRing0() ? "Kernel" : "Process", current->pid(), current->name().characters());
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word ss;
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dword esp;
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if (current->isRing0()) {
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ss = regs.ds;
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esp = regs.esp;
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} else {
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ss = regs.ss_if_crossRing;
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esp = regs.esp_if_crossRing;
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}
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kprintf("pc=%w:%x ds=%w es=%w fs=%w gs=%w\n", regs.cs, regs.eip, regs.ds, regs.es, regs.fs, regs.gs);
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kprintf("eax=%x ebx=%x ecx=%x edx=%x\n", regs.eax, regs.ebx, regs.ecx, regs.edx);
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kprintf("ebp=%x esp=%x esi=%x edi=%x\n", regs.ebp, esp, regs.esi, regs.edi);
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if (current->isRing0()) {
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kprintf("Oh shit, we've crashed in ring 0 :(\n");
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HANG;
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}
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HANG;
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Process::processDidCrash(current);
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}
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// 13: General Protection Fault
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EH_ENTRY(13);
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void exception_13_handler(RegisterDumpWithExceptionCode& regs)
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{
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kprintf("%s GPF: %u(%s)\n", current->isRing0() ? "Kernel" : "User", current->pid(), current->name().characters());
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word ss;
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dword esp;
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if (current->isRing0()) {
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ss = regs.ds;
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esp = regs.esp;
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} else {
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ss = regs.ss_if_crossRing;
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esp = regs.esp_if_crossRing;
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}
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kprintf("exception code: %w\n", regs.exception_code);
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kprintf("pc=%w:%x ds=%w es=%w fs=%w gs=%w\n", regs.cs, regs.eip, regs.ds, regs.es, regs.fs, regs.gs);
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kprintf("eax=%x ebx=%x ecx=%x edx=%x\n", regs.eax, regs.ebx, regs.ecx, regs.edx);
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kprintf("ebp=%x esp=%x esi=%x edi=%x\n", regs.ebp, esp, regs.esi, regs.edi);
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if (current->isRing0()) {
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kprintf("Oh shit, we've crashed in ring 0 :(\n");
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HANG;
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}
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Process::processDidCrash(current);
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}
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// 14: Page Fault
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EH_ENTRY(14);
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void exception_14_handler(RegisterDumpWithExceptionCode& regs)
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{
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ASSERT(current);
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dword faultAddress;
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asm ("movl %%cr2, %%eax":"=a"(faultAddress));
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dbgprintf("Ring%u page fault in %s(%u), %s laddr=%p\n",
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regs.cs & 3,
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current->name().characters(),
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current->pid(),
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regs.exception_code & 2 ? "write" : "read",
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faultAddress);
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word ss;
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dword esp;
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if (current->isRing0()) {
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ss = regs.ds;
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esp = regs.esp;
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} else {
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ss = regs.ss_if_crossRing;
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esp = regs.esp_if_crossRing;
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}
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#ifdef PAGE_FAULT_DEBUG
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dbgprintf("exception code: %w\n", regs.exception_code);
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dbgprintf("pc=%w:%x ds=%w es=%w fs=%w gs=%w\n", regs.cs, regs.eip, regs.ds, regs.es, regs.fs, regs.gs);
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dbgprintf("stk=%w:%x\n", ss, esp);
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dbgprintf("eax=%x ebx=%x ecx=%x edx=%x\n", regs.eax, regs.ebx, regs.ecx, regs.edx);
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dbgprintf("ebp=%x esp=%x esi=%x edi=%x\n", regs.ebp, esp, regs.esi, regs.edi);
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byte* codeptr = (byte*)regs.eip;
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dbgprintf("code: %b %b %b %b %b %b %b %b\n",
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codeptr[0],
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codeptr[1],
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codeptr[2],
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codeptr[3],
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codeptr[4],
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codeptr[5],
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codeptr[6],
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codeptr[7]
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);
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#endif
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if (current->isRing0())
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HANG;
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auto response = MM.handle_page_fault(PageFault(regs.exception_code, LinearAddress(faultAddress)));
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if (response == PageFaultResponse::ShouldCrash) {
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kprintf("Crashing after unresolved page fault\n");
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Process::processDidCrash(current);
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} else if (response == PageFaultResponse::Continue) {
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#ifdef PAGE_FAULT_DEBUG
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dbgprintf("Continuing after resolved page fault\n");
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#endif
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} else {
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ASSERT_NOT_REACHED();
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}
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}
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#define EH(i, msg) \
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static void _exception ## i () \
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{ \
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kprintf(msg"\n"); \
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DWORD cr0, cr2, cr3, cr4; \
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asm ("movl %%cr0, %%eax":"=a"(cr0)); \
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asm ("movl %%cr2, %%eax":"=a"(cr2)); \
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asm ("movl %%cr3, %%eax":"=a"(cr3)); \
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asm ("movl %%cr4, %%eax":"=a"(cr4)); \
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kprintf("CR0=%x CR2=%x CR3=%x CR4=%x\n", cr0, cr2, cr3, cr4); \
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HANG; \
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}
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EH(0, "Divide error")
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EH(1, "Debug exception")
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EH(2, "Unknown error")
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EH(3, "Breakpoint")
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EH(4, "Overflow")
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EH(5, "Bounds check")
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EH(6, "Invalid opcode")
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EH(7, "Coprocessor not available")
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EH(8, "Double fault")
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EH(9, "Coprocessor segment overrun")
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EH(10, "Invalid TSS")
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EH(11, "Segment not present")
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EH(12, "Stack exception")
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EH(13, "General protection fault")
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EH(14, "Page fault")
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EH(15, "Unknown error")
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EH(16, "Coprocessor error")
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static void writeRawGDTEntry(WORD selector, DWORD low, DWORD high)
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{
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WORD i = (selector & 0xfffc) >> 3;
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s_gdt[i].low = low;
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s_gdt[i].high = high;
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if (i > s_gdtLength) {
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s_gdtr.size = (s_gdtLength + 1) * 8;
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}
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}
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void writeGDTEntry(WORD selector, Descriptor& descriptor)
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{
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writeRawGDTEntry(selector, descriptor.low, descriptor.high);
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}
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Descriptor& getGDTEntry(WORD selector)
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{
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WORD i = (selector & 0xfffc) >> 3;
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return *(Descriptor*)(&s_gdt[i]);
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}
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void flushGDT()
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{
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s_gdtr.address = s_gdt;
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s_gdtr.size = (s_gdtLength * 8) - 1;
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asm("lgdt %0"::"m"(s_gdtr));
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}
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void gdt_init()
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{
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s_gdt = static_cast<Descriptor*>(kmalloc_eternal(sizeof(Descriptor) * 256));
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s_gdtLength = 5;
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s_gdt_freelist = new Vector<word, KmallocEternalAllocator>();
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s_gdt_freelist->ensureCapacity(256);
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for (size_t i = s_gdtLength; i < 256; ++i)
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s_gdt_freelist->unchecked_append(i * 8);
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s_gdtLength = 256;
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s_gdtr.address = s_gdt;
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s_gdtr.size = (s_gdtLength * 8) - 1;
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writeRawGDTEntry(0x0000, 0x00000000, 0x00000000);
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writeRawGDTEntry(0x0008, 0x0000ffff, 0x00cf9a00);
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writeRawGDTEntry(0x0010, 0x0000ffff, 0x00cf9200);
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writeRawGDTEntry(0x0018, 0x0000ffff, 0x00cffa00);
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writeRawGDTEntry(0x0020, 0x0000ffff, 0x00cff200);
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flushGDT();
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}
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static void unimp_trap()
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{
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kprintf("Unhandled IRQ.");
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HANG;
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}
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void registerIRQHandler(byte irq, IRQHandler& handler)
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{
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ASSERT(!s_irqHandler[irq]);
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s_irqHandler[irq] = &handler;
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kprintf("irq handler for %u: %p\n", irq, &handler);
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registerInterruptHandler(IRQ_VECTOR_BASE + irq, commonIRQEntry);
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}
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void unregisterIRQHandler(byte irq, IRQHandler& handler)
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{
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ASSERT(s_irqHandler[irq] == &handler);
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s_irqHandler[irq] = nullptr;
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}
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void registerInterruptHandler(BYTE index, void (*f)())
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{
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s_idt[index].low = 0x00080000 | LSW((f));
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s_idt[index].high = ((DWORD)(f) & 0xffff0000) | 0x8e00;
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flushIDT();
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}
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void registerUserCallableInterruptHandler(BYTE index, void (*f)())
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{
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s_idt[index].low = 0x00080000 | LSW((f));
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s_idt[index].high = ((DWORD)(f) & 0xffff0000) | 0xef00;
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flushIDT();
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}
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void flushIDT()
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{
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asm("lidt %0"::"m"(s_idtr));
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}
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/* If an 8259 gets cranky, it'll generate a spurious IRQ7.
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* ATM I don't have a clear grasp on when/why this happens,
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* so I ignore them and assume it makes no difference.
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*/
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extern "C" void irq7_handler();
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asm(
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".globl irq7_handler \n"
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"irq7_handler: \n"
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" iret\n"
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);
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void idt_init()
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{
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s_idt = static_cast<Descriptor*>(kmalloc_eternal(sizeof(Descriptor) * 256));
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s_idtr.address = s_idt;
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s_idtr.size = 0x100 * 8;
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for (BYTE i = 0xff; i > 0x10; --i)
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registerInterruptHandler(i, unimp_trap);
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registerInterruptHandler(0x00, _exception0);
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registerInterruptHandler(0x01, _exception1);
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registerInterruptHandler(0x02, _exception2);
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registerInterruptHandler(0x03, _exception3);
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registerInterruptHandler(0x04, _exception4);
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registerInterruptHandler(0x05, _exception5);
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registerInterruptHandler(0x06, exception_6_entry);
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registerInterruptHandler(0x07, _exception7);
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registerInterruptHandler(0x08, _exception8);
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registerInterruptHandler(0x09, _exception9);
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registerInterruptHandler(0x0a, _exception10);
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registerInterruptHandler(0x0b, _exception11);
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registerInterruptHandler(0x0c, _exception12);
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registerInterruptHandler(0x0d, exception_13_entry);
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registerInterruptHandler(0x0e, exception_14_entry);
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registerInterruptHandler(0x0f, _exception15);
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registerInterruptHandler(0x10, _exception16);
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registerInterruptHandler(0x57, irq7_handler);
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s_irqHandler = static_cast<IRQHandler**>(kmalloc_eternal(sizeof(IRQHandler*) * 16));
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for (byte i = 0; i < 16; ++i) {
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s_irqHandler[i] = nullptr;
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}
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flushIDT();
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}
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void loadTaskRegister(WORD selector)
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{
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asm("ltr %0"::"r"(selector));
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}
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void handleIRQ()
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{
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WORD isr = PIC::getISR();
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if (!isr) {
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kprintf("Spurious IRQ\n");
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return;
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}
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byte irq;
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for (byte i = 0; i < 16; ++i) {
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if (isr & (1 << i)) {
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irq = i;
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break;
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}
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}
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if (s_irqHandler[irq])
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s_irqHandler[irq]->handleIRQ();
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PIC::eoi(irq);
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}
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void __assertion_failed(const char* msg, const char* file, unsigned line, const char* func)
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{
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asm volatile("cli");
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kprintf("ASSERTION FAILED: %s\n%s:%u in %s\n", msg, file, line, func);
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asm volatile("hlt");
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}
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