mirror of
https://github.com/taigrr/gopher-os
synced 2025-01-18 04:43:13 -08:00
Install exception handlers for page faults/GPFs and provide kernel.Panic
This commit is contained in:
Achilleas Anagnostopoulos
parent
c5aa5fe05f
commit
6e8d504ae8
@ -1,10 +1,11 @@
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package kmain
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import (
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"github.com/achilleasa/gopher-os/kernel"
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"github.com/achilleasa/gopher-os/kernel/hal"
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"github.com/achilleasa/gopher-os/kernel/hal/multiboot"
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"github.com/achilleasa/gopher-os/kernel/kfmt/early"
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"github.com/achilleasa/gopher-os/kernel/mem/pmm/allocator"
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"github.com/achilleasa/gopher-os/kernel/mem/vmm"
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)
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// Kmain is the only Go symbol that is visible (exported) from the rt0 initialization
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@ -24,7 +25,10 @@ func Kmain(multibootInfoPtr, kernelStart, kernelEnd uintptr) {
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hal.InitTerminal()
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hal.ActiveTerminal.Clear()
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if err := allocator.Init(kernelStart, kernelEnd); err != nil {
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early.Printf("[%s] error: %s\n", err.Module, err.Message)
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var err *kernel.Error
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if err = allocator.Init(kernelStart, kernelEnd); err != nil {
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kernel.Panic(err)
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} else if err = vmm.Init(); err != nil {
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kernel.Panic(err)
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}
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}
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@ -2,10 +2,23 @@ package vmm
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import (
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"github.com/achilleasa/gopher-os/kernel"
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"github.com/achilleasa/gopher-os/kernel/cpu"
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"github.com/achilleasa/gopher-os/kernel/irq"
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"github.com/achilleasa/gopher-os/kernel/kfmt/early"
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"github.com/achilleasa/gopher-os/kernel/mem/pmm"
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)
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var frameAllocator FrameAllocatorFn
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var (
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// frameAllocator points to a frame allocator function registered using
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// SetFrameAllocator.
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frameAllocator FrameAllocatorFn
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// the following functions are mocked by tests and are automatically
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// inlined by the compiler.
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panicFn = kernel.Panic
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handleExceptionWithCodeFn = irq.HandleExceptionWithCode
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readCR2Fn = cpu.ReadCR2
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)
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// FrameAllocatorFn is a function that can allocate physical frames.
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type FrameAllocatorFn func() (pmm.Frame, *kernel.Error)
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@ -15,3 +28,51 @@ type FrameAllocatorFn func() (pmm.Frame, *kernel.Error)
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func SetFrameAllocator(allocFn FrameAllocatorFn) {
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frameAllocator = allocFn
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}
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func pageFaultHandler(errorCode uint64, frame *irq.Frame, regs *irq.Regs) {
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early.Printf("\nPage fault while accessing address: 0x%16x\nReason: ", readCR2Fn())
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switch {
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case errorCode == 0:
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early.Printf("read from non-present page")
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case errorCode == 1:
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early.Printf("page protection violation (read)")
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case errorCode == 2:
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early.Printf("write to non-present page")
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case errorCode == 3:
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early.Printf("page protection violation (write)")
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case errorCode == 4:
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early.Printf("page-fault in user-mode")
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case errorCode == 8:
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early.Printf("page table has reserved bit set")
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case errorCode == 16:
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early.Printf("instruction fetch")
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default:
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early.Printf("unknown")
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}
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early.Printf("\n\nRegisters:\n")
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regs.Print()
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frame.Print()
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// TODO: Revisit this when user-mode tasks are implemented
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panicFn(nil)
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}
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func generalProtectionFaultHandler(_ uint64, frame *irq.Frame, regs *irq.Regs) {
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early.Printf("\nGeneral protection fault while accessing address: 0x%x\n", readCR2Fn())
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early.Printf("Registers:\n")
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regs.Print()
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frame.Print()
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// TODO: Revisit this when user-mode tasks are implemented
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panicFn(nil)
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}
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// Init initializes the vmm system and installs paging-related exception
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// handlers.
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func Init() *kernel.Error {
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handleExceptionWithCodeFn(irq.PageFaultException, pageFaultHandler)
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handleExceptionWithCodeFn(irq.GPFException, generalProtectionFaultHandler)
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return nil
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}
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169
kernel/mem/vmm/vmm_test.go
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169
kernel/mem/vmm/vmm_test.go
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@ -0,0 +1,169 @@
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package vmm
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import (
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"bytes"
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"strings"
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"testing"
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"unsafe"
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"github.com/achilleasa/gopher-os/kernel"
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"github.com/achilleasa/gopher-os/kernel/cpu"
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"github.com/achilleasa/gopher-os/kernel/driver/video/console"
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"github.com/achilleasa/gopher-os/kernel/hal"
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"github.com/achilleasa/gopher-os/kernel/irq"
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)
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func TestPageFaultHandler(t *testing.T) {
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defer func() {
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panicFn = kernel.Panic
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readCR2Fn = cpu.ReadCR2
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}()
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specs := []struct {
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errCode uint64
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expReason string
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expPanic bool
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}{
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{
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0,
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"read from non-present page",
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true,
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},
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{
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1,
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"page protection violation (read)",
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true,
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},
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{
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2,
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"write to non-present page",
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true,
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},
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{
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3,
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"page protection violation (write)",
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true,
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},
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{
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4,
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"page-fault in user-mode",
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true,
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},
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{
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8,
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"page table has reserved bit set",
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true,
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},
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{
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16,
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"instruction fetch",
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true,
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},
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{
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0xf00,
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"unknown",
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true,
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},
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}
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var (
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regs irq.Regs
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frame irq.Frame
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)
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readCR2Fn = func() uint64 {
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return 0xbadf00d000
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}
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panicCalled := false
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panicFn = func(_ *kernel.Error) {
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panicCalled = true
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}
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for specIndex, spec := range specs {
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fb := mockTTY()
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panicCalled = false
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pageFaultHandler(spec.errCode, &frame, ®s)
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if got := readTTY(fb); !strings.Contains(got, spec.expReason) {
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t.Errorf("[spec %d] expected reason %q; got output:\n%q", specIndex, spec.expReason, got)
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continue
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}
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if spec.expPanic != panicCalled {
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t.Errorf("[spec %d] expected panic %t; got %t", specIndex, spec.expPanic, panicCalled)
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}
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}
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}
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func TestGPtHandler(t *testing.T) {
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defer func() {
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panicFn = kernel.Panic
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readCR2Fn = cpu.ReadCR2
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}()
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var (
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regs irq.Regs
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frame irq.Frame
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fb = mockTTY()
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)
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readCR2Fn = func() uint64 {
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return 0xbadf00d000
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}
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panicCalled := false
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panicFn = func(_ *kernel.Error) {
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panicCalled = true
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}
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generalProtectionFaultHandler(0, &frame, ®s)
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exp := "\nGeneral protection fault while accessing address: 0xbadf00d000\nRegisters:\nRAX = 0000000000000000 RBX = 0000000000000000\nRCX = 0000000000000000 RDX = 0000000000000000\nRSI = 0000000000000000 RDI = 0000000000000000\nRBP = 0000000000000000\nR8 = 0000000000000000 R9 = 0000000000000000\nR10 = 0000000000000000 R11 = 0000000000000000\nR12 = 0000000000000000 R13 = 0000000000000000\nR14 = 0000000000000000 R15 = 0000000000000000\nRIP = 0000000000000000 CS = 0000000000000000\nRSP = 0000000000000000 SS = 0000000000000000\nRFL = 0000000000000000"
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if got := readTTY(fb); got != exp {
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t.Errorf("expected output:\n%q\ngot:\n%q", exp, got)
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}
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if !panicCalled {
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t.Error("expected kernel.Panic to be called")
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}
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}
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func TestInit(t *testing.T) {
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defer func() {
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handleExceptionWithCodeFn = irq.HandleExceptionWithCode
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}()
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handleExceptionWithCodeFn = func(_ irq.ExceptionNum, _ irq.ExceptionHandlerWithCode) {}
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if err := Init(); err != nil {
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t.Fatal(err)
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}
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}
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func readTTY(fb []byte) string {
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var buf bytes.Buffer
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for i := 0; i < len(fb); i += 2 {
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ch := fb[i]
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if ch == 0 {
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if i+2 < len(fb) && fb[i+2] != 0 {
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buf.WriteByte('\n')
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}
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continue
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}
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buf.WriteByte(ch)
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}
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return buf.String()
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}
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func mockTTY() []byte {
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// Mock a tty to handle early.Printf output
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mockConsoleFb := make([]byte, 160*25)
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mockConsole := &console.Ega{}
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mockConsole.Init(80, 25, uintptr(unsafe.Pointer(&mockConsoleFb[0])))
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hal.ActiveTerminal.AttachTo(mockConsole)
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return mockConsoleFb
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}
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24
kernel/panic.go
Normal file
24
kernel/panic.go
Normal file
@ -0,0 +1,24 @@
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package kernel
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import (
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"github.com/achilleasa/gopher-os/kernel/cpu"
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"github.com/achilleasa/gopher-os/kernel/kfmt/early"
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)
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var (
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// cpuHaltFn is mocked by tests and is automatically inlined by the compiler.
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cpuHaltFn = cpu.Halt
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)
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// Panic outputs the supplied error (if not nil) to the console and halts the
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// CPU. Calls to Panic never return.
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func Panic(err *Error) {
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early.Printf("\n-----------------------------------\n")
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if err != nil {
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early.Printf("[%s] unrecoverable error: %s\n", err.Module, err.Message)
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}
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early.Printf("*** kernel panic: system halted ***")
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early.Printf("\n-----------------------------------\n")
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cpuHaltFn()
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}
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84
kernel/panic_test.go
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84
kernel/panic_test.go
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@ -0,0 +1,84 @@
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package kernel
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import (
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"bytes"
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"testing"
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"unsafe"
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"github.com/achilleasa/gopher-os/kernel/cpu"
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"github.com/achilleasa/gopher-os/kernel/driver/video/console"
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"github.com/achilleasa/gopher-os/kernel/hal"
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)
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func TestPanic(t *testing.T) {
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defer func() {
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cpuHaltFn = cpu.Halt
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}()
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var cpuHaltCalled bool
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cpuHaltFn = func() {
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cpuHaltCalled = true
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}
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t.Run("with error", func(t *testing.T) {
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cpuHaltCalled = false
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fb := mockTTY()
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err := &Error{Module: "test", Message: "panic test"}
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Panic(err)
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exp := "\n-----------------------------------\n[test] unrecoverable error: panic test\n*** kernel panic: system halted ***\n-----------------------------------"
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if got := readTTY(fb); got != exp {
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t.Fatalf("expected to get:\n%q\ngot:\n%q", exp, got)
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}
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if !cpuHaltCalled {
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t.Fatal("expected cpu.Halt() to be called by Panic")
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}
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})
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t.Run("without error", func(t *testing.T) {
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cpuHaltCalled = false
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fb := mockTTY()
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Panic(nil)
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exp := "\n-----------------------------------\n*** kernel panic: system halted ***\n-----------------------------------"
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if got := readTTY(fb); got != exp {
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t.Fatalf("expected to get:\n%q\ngot:\n%q", exp, got)
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}
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if !cpuHaltCalled {
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t.Fatal("expected cpu.Halt() to be called by Panic")
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}
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})
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}
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func readTTY(fb []byte) string {
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var buf bytes.Buffer
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for i := 0; i < len(fb); i += 2 {
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ch := fb[i]
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if ch == 0 {
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if i+2 < len(fb) && fb[i+2] != 0 {
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buf.WriteByte('\n')
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}
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continue
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}
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buf.WriteByte(ch)
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}
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return buf.String()
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}
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func mockTTY() []byte {
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// Mock a tty to handle early.Printf output
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mockConsoleFb := make([]byte, 160*25)
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mockConsole := &console.Ega{}
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mockConsole.Init(80, 25, uintptr(unsafe.Pointer(&mockConsoleFb[0])))
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hal.ActiveTerminal.AttachTo(mockConsole)
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return mockConsoleFb
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}
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