[zion] Use a separate stack for PF and GP faults in the kernel.

zion/common/gdt.cpp

@@ -93,4 +93,8 @@ void InitGdt() {
           : "rax");
 }
 
+void SetIst1(uint64_t* ist1) {
+  gTaskStateSegment.ist1 = reinterpret_cast<uint64_t>(ist1);
+}
+
 void SetRsp0(uint64_t rsp0) { gTaskStateSegment.rsp0 = rsp0; }

zion/common/gdt.h

@@ -4,4 +4,6 @@
 
 void InitGdt();
 
+void SetIst1(uint64_t* ist1);
+
 void SetRsp0(uint64_t rsp0);

zion/interrupt/interrupt.cpp

@@ -30,12 +30,12 @@ struct InterruptDescriptor {
 
 static InterruptDescriptor gIdt[256];
 
-InterruptDescriptor CreateDescriptor(void isr(void)) {
+InterruptDescriptor CreateDescriptor(void isr(void), uint8_t ist = 0) {
   uint64_t offset = reinterpret_cast<uint64_t>(isr);
   return InterruptDescriptor{
       .offset_low = static_cast<uint16_t>(offset),
       .selector = KERNEL_CS,
-      .ist = 0,
+      .ist = ist,
       .flags = IDT_INTERRUPT_GATE,
       .offset_medium = static_cast<uint16_t>(offset >> 16),
       .offset_high = static_cast<uint32_t>(offset >> 32),
@@ -192,4 +192,15 @@ void InitIdt() {
   asm volatile("lidt %0" ::"m"(idtp));
 }
 
+void UpdateFaultHandlersToIst1() {
+  gIdt[13] = CreateDescriptor(isr_protection_fault, 1);
+  gIdt[14] = CreateDescriptor(isr_page_fault, 1);
+
+  InterruptDescriptorTablePointer idtp{
+      .size = sizeof(gIdt),
+      .base = reinterpret_cast<uint64_t>(gIdt),
+  };
+  asm volatile("lidt %0" ::"m"(idtp));
+}
+
 void RegisterPciPort(const glcr::RefPtr<Port>& port) { pci1_port = port; }

zion/interrupt/interrupt.h

@@ -6,4 +6,6 @@
 
 void InitIdt();
 
+void UpdateFaultHandlersToIst1();
+
 void RegisterPciPort(const glcr::RefPtr<Port>& port);

zion/memory/kernel_stack_manager.cpp

@@ -1,5 +1,6 @@
 #include "memory/kernel_stack_manager.h"
 
+#include "common/gdt.h"
 #include "debug/debug.h"
 #include "memory/paging_util.h"
 
@@ -11,6 +12,8 @@ KernelStackManager* gKernelStackManager;
 
 void KernelStackManager::Init() {
   gKernelStackManager = new KernelStackManager();
+
+  SetIst1(gKernelStackManager->AllocateKernelStack());
 }
 
 KernelStackManager::KernelStackManager()

zion/zion.cpp

@@ -38,6 +38,10 @@ extern "C" void zion() {
   dbgln("[boot] Init Kernel Stack Manager.");
   KernelStackManager::Init();
 
+  // The KernelStackManager sets Ist1 as a part of initialization so we can use
+  // it now.
+  UpdateFaultHandlersToIst1();
+
   dbgln("[boot] Init syscalls.");
   InitSyscall();