Kernel: Generate page fault events from the kernel profiler

Hook the kernel page fault handler and capture page fault events when
the fault has a current thread attached in TLS. We capture the eip and
ebp so we can unwind the stack and locate which pieces of code are
generating the most page faults.

Co-authored-by: Gunnar Beutner <gbeutner@serenityos.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/Kernel/Arch/i386/CPU.cpp b/Kernel/Arch/i386/CPU.cpp
index be267ea97b..10b8136662 100644
--- a/Kernel/Arch/i386/CPU.cpp
+++ b/Kernel/Arch/i386/CPU.cpp
@@ -23,6 +23,7 @@
 #include <Kernel/Interrupts/UnhandledInterruptHandler.h>
 #include <Kernel/KSyms.h>
 #include <Kernel/Panic.h>
+#include <Kernel/PerformanceManager.h>
 #include <Kernel/Process.h>
 #include <Kernel/Random.h>
 #include <Kernel/Thread.h>
@@ -243,8 +244,11 @@ void page_fault_handler(TrapFrame* trap)
 
     auto current_thread = Thread::current();
 
-    if (current_thread)
+    if (current_thread) {
         current_thread->set_handling_page_fault(true);
+        PerformanceManager::add_page_fault_event(*current_thread, regs);
+    }
+
     ScopeGuard guard = [current_thread] {
         if (current_thread)
             current_thread->set_handling_page_fault(false);