From 461194fdfd7fbbf531d99ec1836985ad5749660a Mon Sep 17 00:00:00 2001
From: ngiddings <nathang567@gmail.com>
Date: Sat, 17 Apr 2021 06:26:56 -0500
Subject: [PATCH] Fixed initialize_context() Function did not take 'popal'
 instruction into account when initializing stack

---
 src/x86/context.c | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/src/x86/context.c b/src/x86/context.c
index 9be0f1a..9da0bb2 100644
--- a/src/x86/context.c
+++ b/src/x86/context.c
@@ -1,6 +1,24 @@
 #include "context.h"
 #include "pageallocator.h"
 #include "mmgr.h"
+#include "string.h"
+
+struct process_state_t
+{
+    uint32_t edi;
+    uint32_t esi;
+    uint32_t ebp;
+    uint32_t esp_temp;
+    uint32_t ebx;
+    uint32_t edx;
+    uint32_t ecx;
+    uint32_t eax;
+    uint32_t eip;
+    uint32_t cs;
+    uint32_t flags;
+    uint32_t esp;
+    uint32_t ss;
+};
 
 void *initialize_context(void *task_entry, struct page_stack_t *page_stack)
 {
@@ -9,16 +27,18 @@ void *initialize_context(void *task_entry, struct page_stack_t *page_stack)
     unmap_page((void*)0xFF7FE000);
     unmap_page((void*)0xFF7FC000);
     uint32_t flags;
-    uint32_t *stack = (uint32_t*)((void*)0xFF800000 - 20);
+    struct process_state_t *stack = (struct process_state_t*)((void*)0xFF800000 - 20 - 8*4);
     asm("pushf; "
         "mov (%%esp), %0; "
         "popf; "
         : "=r"(flags));
-    stack[0] = (uint32_t)task_entry;
-    stack[1] = 27;
-    stack[2] = flags;
-    stack[3] = 0xFF7FE000;
-    stack[4] = 35;
+    memset(stack, 0, sizeof(*stack));
+    stack->eip = (uint32_t)task_entry;
+    stack->cs = 27;
+    stack->flags = flags;
+    stack->esp = 0xFF7FE000;
+    stack->ss = 35;
+    stack->esp_temp = &stack->eax;
     return (void*)stack;
 }