From c22a4301ed0341477295d7ae481b1223d2428eaa Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Wed, 25 Dec 2019 11:34:07 +0100
Subject: [PATCH] Kernel: Interpret "reserved bit violation" page faults
 correctly

We don't actually react to these in any meaningful way other than
crashing, but let's at least print the correct information. :^)
---
 Kernel/Arch/i386/CPU.cpp | 3 ++-
 Kernel/Arch/i386/CPU.h   | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/Kernel/Arch/i386/CPU.cpp b/Kernel/Arch/i386/CPU.cpp
index 8d7daee5d7..1d713b584d 100644
--- a/Kernel/Arch/i386/CPU.cpp
+++ b/Kernel/Arch/i386/CPU.cpp
@@ -279,10 +279,11 @@ void page_fault_handler(RegisterDump regs)
             return;
         }
 
-        kprintf("\033[31;1m%s(%u:%u) Unrecoverable page fault, %s%s address %p\033[0m\n",
+        kprintf("\033[31;1m%s(%u:%u) Unrecoverable page fault, %s%s%s address %p\033[0m\n",
             current->process().name().characters(),
             current->pid(),
             current->tid(),
+                regs.exception_code & PageFaultFlags::ReservedBitViolation ? "reserved bit violation / " : "",
             regs.exception_code & PageFaultFlags::InstructionFetch ? "instruction fetch / " : "",
             regs.exception_code & PageFaultFlags::Write ? "write to" : "read from",
             fault_address);
diff --git a/Kernel/Arch/i386/CPU.h b/Kernel/Arch/i386/CPU.h
index 0f592e9037..d946a783f0 100644
--- a/Kernel/Arch/i386/CPU.h
+++ b/Kernel/Arch/i386/CPU.h
@@ -348,7 +348,8 @@ struct PageFaultFlags {
         Write = 0x02,
         UserMode = 0x04,
         SupervisorMode = 0x00,
-        InstructionFetch = 0x08,
+        ReservedBitViolation = 0x08,
+        InstructionFetch = 0x10,
     };
 };