From 1cb5c671f7a0c77787d3d6d3ba7f922dafc5d44d Mon Sep 17 00:00:00 2001
From: Curle <curle@gemwire.uk>
Date: Mon, 9 Nov 2020 18:39:34 +0000
Subject: [PATCH] Add basic stack unwinding functionality

---
 CMakeLists.txt                   |  3 ++-
 chroma/inc/kernel/chroma.h       |  1 +
 chroma/inc/kernel/system/stack.h | 15 +++++++++++++++
 chroma/system/memory/stack.c     | 29 +++++++++++++++++++++++++++++
 4 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 chroma/inc/kernel/system/stack.h
 create mode 100644 chroma/system/memory/stack.c

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7b15e04..14cc4bd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -19,6 +19,7 @@ SET(src_files
     ${CMAKE_SOURCE_DIR}/chroma/system/rw.c
     ${CMAKE_SOURCE_DIR}/chroma/system/serial.c
     ${CMAKE_SOURCE_DIR}/chroma/system/pci.c
+    ${CMAKE_SOURCE_DIR}/chroma/system/memory/stack.c
     ${CMAKE_SOURCE_DIR}/chroma/system/memory/paging.c
     ${CMAKE_SOURCE_DIR}/chroma/system/memory/abstract_allocator.c
     ${CMAKE_SOURCE_DIR}/chroma/system/memory/physmem.c
@@ -53,5 +54,5 @@ set_property(SOURCE ${src_no_sse} PROPERTY COMPILE_FLAGS -mgeneral-regs-only)
 add_executable(kernel)
 
 target_sources(kernel PUBLIC ${src_preamble} PUBLIC ${src_files} PUBLIC ${src_no_sse} PUBLIC ${lib_files} PUBLIC ${CMAKE_SOURCE_DIR}/font.o PUBLIC ${src_epilogue})
-target_compile_options(kernel PRIVATE -ffreestanding -O2 -Wall -Wextra -Wall -Werror -pedantic -fPIC -fno-exceptions )
+target_compile_options(kernel PRIVATE -ffreestanding -O0 -Wall -Wextra -Wall -Werror -pedantic -fPIC -fno-exceptions -fno-omit-frame-pointer -mno-red-zone -fno-stack-protector )
 target_link_options(kernel PRIVATE -T linker.ld -ffreestanding -O2 -nostdlib -nostartfiles -lgcc)
diff --git a/chroma/inc/kernel/chroma.h b/chroma/inc/kernel/chroma.h
index 5186271..8ec5f92 100644
--- a/chroma/inc/kernel/chroma.h
+++ b/chroma/inc/kernel/chroma.h
@@ -18,6 +18,7 @@
 #include <kernel/system/io.h>
 #include <kernel/system/memory.h>
 #include <kernel/system/pci.h>
+#include <kernel/system/stack.h>
 
 //Removed cause "wacky copyrighted stuff"
 //#include <kernel/system/screen.h>
diff --git a/chroma/inc/kernel/system/stack.h b/chroma/inc/kernel/system/stack.h
new file mode 100644
index 0000000..14bedec
--- /dev/null
+++ b/chroma/inc/kernel/system/stack.h
@@ -0,0 +1,15 @@
+#pragma once
+#include <stddef.h>
+#include <stdint.h>
+
+/************************
+ *** Team Kitty, 2020 ***
+ ***     Chroma       ***
+ ***********************/
+
+typedef struct stackframe {
+  struct stackframe* rbp;
+  size_t rip;
+} stackframe_t;
+
+void StackTrace(size_t cycles);
\ No newline at end of file
diff --git a/chroma/system/memory/stack.c b/chroma/system/memory/stack.c
new file mode 100644
index 0000000..45010a0
--- /dev/null
+++ b/chroma/system/memory/stack.c
@@ -0,0 +1,29 @@
+#include <kernel/chroma.h>
+/************************
+ *** Team Kitty, 2020 ***
+ ***     Chroma       ***
+ ***********************/
+
+/* 
+ * This file aims to implement stack unwinding
+ * to trace faulty functions.
+ * 
+ * I was in the middle of debugging a jump to null
+ * when i started creating this, so there will be a
+ * lot of functionality here left over from that
+ * initial goal, probably...
+ * 
+ * //TODO: Rework this to allow unwinding function parameters on call.
+ */
+
+void StackTrace(size_t cycles) {
+    struct stackframe* stack;
+
+    __asm__ __volatile__ ("mov %%rbp, %[dest]" : [dest] "=r" (stack) : :);
+    SerialPrintf("[Trace] Beginning stack trace. RBP is currently 0x%p\r\n", stack);
+    for(size_t frame = 0; stack != 0 && frame < cycles; ++frame) {
+        SerialPrintf("[Trace]   0x%p \r\n", stack->rip);
+        stack = stack->rbp;
+    }
+    SerialPrintf("[Trace] Stack trace over.\r\n");
+}
\ No newline at end of file