From 0d437cfcca4f117d27e78fb2873b02b869a08442 Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Wed, 7 Dec 2022 17:39:59 +0100
Subject: [PATCH] Add support for stack traces

---
 kernel/src/arch/CPU.h          |  3 +++
 kernel/src/arch/x86_64/CPU.cpp | 43 ++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/kernel/src/arch/CPU.h b/kernel/src/arch/CPU.h
index 35159630..ac05ed6a 100644
--- a/kernel/src/arch/CPU.h
+++ b/kernel/src/arch/CPU.h
@@ -20,4 +20,7 @@ namespace CPU
     void enable_interrupts();
     void disable_interrupts();
     void wait_for_interrupt();
+
+    void get_stack_trace(void (*callback)(u64, void*), void* arg);
+    void get_stack_trace_at(Registers* regs, void (*callback)(u64, void*), void* arg);
 }
\ No newline at end of file
diff --git a/kernel/src/arch/x86_64/CPU.cpp b/kernel/src/arch/x86_64/CPU.cpp
index 6a9f8600..8d8476c9 100644
--- a/kernel/src/arch/x86_64/CPU.cpp
+++ b/kernel/src/arch/x86_64/CPU.cpp
@@ -3,6 +3,7 @@
 #include "arch/Timer.h"
 #include "arch/x86_64/CPU.h"
 #include "arch/x86_64/IO.h"
+#include "memory/MemoryManager.h"
 #include "thread/Scheduler.h"
 #include <cpuid.h>
 #include <luna/Check.h>
@@ -301,6 +302,17 @@ static void setup_idt()
     u64 cr2;
     asm volatile("mov %%cr2, %0" : "=r"(cr2));
     kerrorln("Page fault at RIP %lx while accessing %lx!", regs->rip, cr2);
+
+    int frame_index = 0;
+    CPU::get_stack_trace_at(
+        regs,
+        [](u64 instruction, void* arg) {
+            int* ptr = (int*)arg;
+            kinfoln("#%d at %p", *ptr, (void*)instruction);
+            (*ptr)++;
+        },
+        &frame_index);
+
     CPU::efficient_halt();
 }
 
@@ -444,6 +456,37 @@ namespace CPU
     {
         task_state_segment.rsp[0] = top;
     }
+
+    struct StackFrame
+    {
+        StackFrame* next;
+        u64 instruction;
+    };
+
+    void get_stack_trace(void (*callback)(u64, void*), void* arg)
+    {
+        u64 rbp;
+        asm volatile("mov %%rbp, %0" : "=r"(rbp));
+        StackFrame* current_frame = (StackFrame*)rbp;
+        // FIXME: Validate that the frame itself is readable, might span across multiple pages
+        while (current_frame && MemoryManager::validate_readable_page((u64)current_frame))
+        {
+            callback(current_frame->instruction, arg);
+            current_frame = current_frame->next;
+        }
+    }
+
+    void get_stack_trace_at(Registers* regs, void (*callback)(u64, void*), void* arg)
+    {
+        callback(regs->rip, arg);
+        StackFrame* current_frame = (StackFrame*)regs->rbp;
+        // FIXME: Validate that the frame itself is readable, might span across multiple pages
+        while (current_frame && MemoryManager::validate_readable_page((u64)current_frame))
+        {
+            callback(current_frame->instruction, arg);
+            current_frame = current_frame->next;
+        }
+    }
 }
 
 // called by kernel_yield