From b6ee4fc3de326f1f6be2e9baab4bca141a9bfa88 Mon Sep 17 00:00:00 2001
From: slinky55 <lbmason55@gmail.com>
Date: Wed, 1 Jul 2026 20:00:22 -0500
Subject: [PATCH] more userspace stuff

---
 deploy_programs.sh            | 21 +++++++++++++++
 kernel/common.S               | 23 +++++++++--------
 kernel/common.h               |  2 ++
 kernel/drivers/pic/pic.S      |  4 +--
 kernel/gdt.h                  |  1 +
 kernel/interrupts.c           |  8 +++++-
 kernel/kmain.c                | 43 +++++++++++++++++++++----------
 kernel/lib/memory.c           |  4 +++
 kernel/lib/memory.h           |  2 +-
 kernel/memory/mm.c            |  3 +++
 kernel/process.h              | 10 ++++++--
 kernel/scheduler.S            |  4 +--
 kernel/scheduler.c            | 28 ++++++++++++++------
 kernel/scheduler.h            |  2 +-
 kernel/syscall.S              | 48 +++++++++++++++++------------------
 kernel/syscall.c              |  4 ++-
 programs/crt0.S               | 25 ++++++++----------
 programs/crt0.s               | 28 --------------------
 programs/main.c               |  6 ++---
 programs/makefile             |  4 +--
 rocklibc/src/rockos/syscall.c | 12 ++++-----
 21 files changed, 161 insertions(+), 121 deletions(-)
 create mode 100755 deploy_programs.sh
 delete mode 100644 programs/crt0.s

diff --git a/deploy_programs.sh b/deploy_programs.sh
new file mode 100755
index 0000000..f970e8e
--- /dev/null
+++ b/deploy_programs.sh
@@ -0,0 +1,21 @@
+#!/bin/bash 
+
+cd rocklibc 
+make clean
+make
+cd .. 
+
+cd programs 
+make clean
+make
+cd .. 
+
+make clean 
+make
+
+cd initrd
+./make_img.sh
+cd ..
+
+make -B
+
diff --git a/kernel/common.S b/kernel/common.S
index 2b1b563..31f5c73 100644
--- a/kernel/common.S
+++ b/kernel/common.S
@@ -20,8 +20,8 @@ io_wait:
 liftoff:
     cli
 
-    mov 4(%esp), %ecx
-    mov 8(%esp), %ebx
+    mov 4(%esp), %ecx 
+    mov 8(%esp), %ebx  
 
     mov $0x23, %ax
     mov %ax, %ds
@@ -29,15 +29,20 @@ liftoff:
     mov %ax, %fs
     mov %ax, %gs
 
-    push $0x23           
-    push %ebx
-    push $0x202
-    push $0x1B
-    push %ecx
+    pushl $0x23         # User Data Segment (SS)
+    pushl %ebx          # User Stack Pointer (ESP)
+    pushl $0x202        # EFLAGS (Interrupts enabled, bit 1 standard)
+    pushl $0x1B         # User Code Segment (CS)
+    pushl %ecx          # User Entry Point (EIP)
 
     xor %eax, %eax
+    xor %ebx, %ebx
+    xor %ecx, %ecx
     xor %edx, %edx
-    
+    xor %esi, %esi
+    xor %edi, %edi
+    xor %ebp, %ebp
+
     iret
 
 .global outb
@@ -121,5 +126,3 @@ outsw:
 fetch_cr3: 
     mov %cr3, %eax 
     ret
-
-.global set_cr3
diff --git a/kernel/common.h b/kernel/common.h
index b7c189a..0cd97ab 100644
--- a/kernel/common.h
+++ b/kernel/common.h
@@ -7,4 +7,6 @@ void enable_interrupts();
 void disable_interrupts();
 uint32_t fetch_cr3();
 
+void liftoff(uint32_t entry_point, uint32_t user_stack) __attribute__((noreturn));
+
 #endif
\ No newline at end of file
diff --git a/kernel/drivers/pic/pic.S b/kernel/drivers/pic/pic.S
index 0719097..da5fff6 100644
--- a/kernel/drivers/pic/pic.S
+++ b/kernel/drivers/pic/pic.S
@@ -33,9 +33,9 @@ init_pic:
     outb %al, $PIC2_DATA 
 
     # mask
-    mov $0xF8, %al
+    mov $0xFF, %al
     outb %al, $PIC1_DATA
-    mov $0x3F, %al
+    mov $0xFF, %al
     outb %al, $PIC2_DATA 
 
     ret
diff --git a/kernel/gdt.h b/kernel/gdt.h
index 43104cf..f4338bb 100644
--- a/kernel/gdt.h
+++ b/kernel/gdt.h
@@ -34,6 +34,7 @@ typedef struct __attribute__((packed)) {
 } tss_entry_t;
 
 void init_gdt();
+void tss_flush();
 
 extern tss_entry_t tss;
 
diff --git a/kernel/interrupts.c b/kernel/interrupts.c
index f9838c1..d53e868 100644
--- a/kernel/interrupts.c
+++ b/kernel/interrupts.c
@@ -110,7 +110,7 @@ void common_interrupt_handler(registers *args) {
         case 13:
         case 15:
         case 16:
-            kprintf("CPU Error: %s", err_messages[args->int_no]);
+            kprintf("CPU Error: %s, %d\n", err_messages[args->int_no], args->error_code);
             break;
         case 14:{
             uint32_t faulting_address;
@@ -119,6 +119,9 @@ void common_interrupt_handler(registers *args) {
             kprintf("Faulted Virtual Address: 0x%x\n", faulting_address);
             kprintf("Error Code: 0x%x\n", args->error_code);
             kprintf("Instruction Pointer: 0x%x\n", args->eip);
+            kprintf("Stack Pointer: 0x%x\n", args->useresp);
+            kprintf("EAX: 0x%x\n", args->eax);
+            kprintf("EFLAGS: 0x%x\n", args->eflags);
             kprintf("Caused by: %s, %s, running in %s mode\n",
                 (args->error_code & 0x01) ? "Protection Violation" : "Page Not Present",
                 (args->error_code & 0x02) ? "Write" : "Read",
@@ -127,15 +130,18 @@ void common_interrupt_handler(registers *args) {
             break;
         }
         case 33: {
+            kprintf("ps2 keyboard interrupt\n");
             uint8_t data = ps2_read_data();
             send_eoi_master();
             break;
         }
         case 46: { // IDE PRIMARY
+            kprintf("IDE PRIMARY interrupt\n");
             send_eoi_slave();
             break;
         }
         case 47: {  // IDE SLAVE
+            kprintf("IDE SLAVE interrupt\n");
             send_eoi_slave();
             break;
         }
diff --git a/kernel/kmain.c b/kernel/kmain.c
index 1b714f7..e58f9ee 100644
--- a/kernel/kmain.c
+++ b/kernel/kmain.c
@@ -1,10 +1,11 @@
 #include "multiboot.h"
 #include "interrupts.h"
 #include "gdt.h"
-#include "scheduler.h"
 #include "common.h"
+#include "scheduler.h"
 #include "vfs.h"
 #include "elf.h"
+#include "gdt.h"
 
 #include <lib/print.h>
 #include <lib/stream.h>
@@ -26,6 +27,9 @@
 extern char __kernel_start;
 extern char __kernel_end;
 
+extern uint32_t page_directory[1024];
+void* kernel_cr3 = page_directory;
+
 void parse_multiboot_modules(uint32_t mbi_vaddr) {
   // find where grub put the boot module containing initrd
   multiboot_info* mbi = (multiboot_info*)mbi_vaddr;
@@ -52,7 +56,8 @@ vfs_node_t* load_initrd() {
   return cpio_read_fs(initrd_module->mod_start);
 }
 
-void load_program(const char* path) {
+void load_root_program(const char* path) {
+  uint32_t kernel_cr3 = fetch_cr3();
   void* cr3 = create_task_pd();
   load_pd(cr3);
   flush_tlb();
@@ -93,12 +98,12 @@ void load_program(const char* path) {
 
       for (uint32_t v = page_start; v < page_end; v += PAGE_SIZE) {
           void* phys_frame = p_alloc_frame();
-          map_page(v, (uint32_t)phys_frame, 0x07);
+          map_page(v, (uint32_t)phys_frame, PAGE_PRESENT | PAGE_WRITABLE | PAGE_USER);
       }
 
       uint32_t data_ptr = ph->p_offset;
       fseek(fd, data_ptr);
-      read(fd, (void*)vstart, ph->p_memsz);
+      read(fd, (void*)vstart, ph->p_filesz);
 
       // 0 out bss
       if (ph->p_memsz > ph->p_filesz) {
@@ -110,15 +115,24 @@ void load_program(const char* path) {
     ph_table_ptr += sizeof(elf_program_header_t);
   }
 
-  uint32_t esp = 0xBFFF0000;
-  void* pesp = p_alloc_frame();
-  map_page(esp - PAGE_SIZE, (uint32_t)pesp, 0x07);
+  uint32_t stack_sz = PAGE_SIZE * 16;
+  uint32_t stack_top = 0xBFFF0000;
+  uint32_t stack_bottom = stack_top - stack_sz;
+  for (uint32_t vaddr = stack_bottom; vaddr < stack_top; vaddr += PAGE_SIZE) {
+    void* phys_frame = p_alloc_frame();
+    map_page(vaddr, (uint32_t)phys_frame, PAGE_PRESENT | PAGE_WRITABLE | PAGE_USER);
+  }
 
-  create_task(e_hdr->e_entry, fetch_cr3(), 1);
-}
+  uint32_t* u_esp = (uint32_t*)stack_top;
+  *(--u_esp) = 0;          // envp = NULL
+  *(--u_esp) = 0;          // argv = NULL
+  *(--u_esp) = 0;          // argc = 0
 
-void start_origin() {
-  load_program("/origin.elf");
+  create_task(e_hdr->e_entry, (uint32_t)cr3, 1, (uint32_t)u_esp);
+  load_pd((void*)kernel_cr3);
+  flush_tlb();
+
+  kprintf("task created for origin program %s\n", path);
 }
 
 void kmain(uint32_t magic, multiboot_info* mbi)  {
@@ -150,13 +164,14 @@ void kmain(uint32_t magic, multiboot_info* mbi)  {
   if (!initrd_root) {
     kprintf("failed to load initrd\n");
   }
+
   mount(vfs_root, initrd_root);
   kprintf("initrd read, mounted @ /\n");
 
-  disable_interrupts();
   init_scheduler();
   enable_interrupts();
 
-  kprintf("loading user program\n");
-  start_origin();
+  kprintf("loading origin program\n");
+  load_root_program("/origin.elf");
+  yield();
 }
diff --git a/kernel/lib/memory.c b/kernel/lib/memory.c
index 6fa9533..698e0eb 100644
--- a/kernel/lib/memory.c
+++ b/kernel/lib/memory.c
@@ -134,4 +134,8 @@ void* kalloc(size_t sz) {
     }
     
     return kalloc(sz);
+}
+
+void kfree(void* ptr) {
+    
 }
\ No newline at end of file
diff --git a/kernel/lib/memory.h b/kernel/lib/memory.h
index a8470fc..3e98ae8 100644
--- a/kernel/lib/memory.h
+++ b/kernel/lib/memory.h
@@ -14,6 +14,6 @@ char* strcpy(char* dest, const char* src);
 
 void kgrow(size_t pages);
 void* kalloc(size_t sz);
-
+void kfree(void* ptr);
 
 #endif
\ No newline at end of file
diff --git a/kernel/memory/mm.c b/kernel/memory/mm.c
index 2d3c175..1b10b30 100644
--- a/kernel/memory/mm.c
+++ b/kernel/memory/mm.c
@@ -18,6 +18,9 @@ extern uint32_t page_directory[1024];
 
 #define TEMP_MAPPING_VADDR 0xDFFF0000
 
+#define USR_PAGE 0x07
+#define SUP_PAGE 0x03
+
 static uint32_t max_address = 0;
 static uint32_t total_available_memory = 0;
 static uint8_t memory_bitmap[BITMAP_SIZE];
diff --git a/kernel/process.h b/kernel/process.h
index 689f691..3dd028e 100644
--- a/kernel/process.h
+++ b/kernel/process.h
@@ -10,15 +10,21 @@ typedef enum {
     STATE_DEAD
 } process_state_t;
 
+typedef enum {
+    PROCESS_FLAG_NONE = 0,
+    PROCESS_FLAG_KERNEL = 1 << 0,
+    PROCESS_FLAG_USER = 1 << 1
+} process_flags_t;
+
 typedef struct {
     uint32_t pid;
     uint32_t esp;
-    uint32_t esp0;
+    uint32_t kstack_top;
     uint32_t cr3;
     process_state_t state;
     uint32_t sleep;
-    void* next;
     uint32_t heap_end;
+    uint32_t flags;
 } __attribute__((packed)) process_t;
 
 #endif 
\ No newline at end of file
diff --git a/kernel/scheduler.S b/kernel/scheduler.S
index fa526e0..83181d5 100644
--- a/kernel/scheduler.S
+++ b/kernel/scheduler.S
@@ -17,9 +17,7 @@ yield: # void yield()
     movl 0(%esp), %ebx      # Get Return EIP
     movl %ebx, 4(%esp)      # Move Return EIP over CS
     addl $4, %esp           # Adjust stack pointer up.
-
-    # the stack now looks like a hardware interrupt just happened, even though we never called one.
-
+    
     pushal
     
     pushl %esp
diff --git a/kernel/scheduler.c b/kernel/scheduler.c
index ef70e01..021e58a 100644
--- a/kernel/scheduler.c
+++ b/kernel/scheduler.c
@@ -1,4 +1,5 @@
 #include <lib/tasks.h>
+#include <lib/print.h>
 #include <lib/memory.h>
 
 #include <memory/mm.h>
@@ -69,7 +70,9 @@ uint32_t switch_context(uint32_t current_esp) {
 
     current_process = next_process;
 
-    tss.esp0 = process_table[current_process].esp0;
+    if (process_table[current_process].flags & PROCESS_FLAG_USER ) {
+        tss.esp0 = process_table[current_process].kstack_top;
+    }
 
     if (fetch_cr3() != process_table[current_process].cr3) {
         load_pd((void*)process_table[current_process].cr3);
@@ -88,14 +91,15 @@ void init_scheduler() {
     process->cr3 = fetch_cr3();
     process->state = STATE_READY;
     process->sleep = 0;
+    process->flags = PROCESS_FLAG_KERNEL;
     total_processes++;
 
-    create_task((uint32_t)idle_task, fetch_cr3(), 0);
+    create_task((uint32_t)idle_task, fetch_cr3(), 0, 0);
 
     current_process = 0;
 }
 
-int create_task(uint32_t entry_point, uint32_t cr3, int user) {
+int create_task(uint32_t entry_point, uint32_t cr3, int user, uint32_t u_esp) {
     if (total_processes >= 16) {
         return 0;
     }
@@ -103,12 +107,14 @@ int create_task(uint32_t entry_point, uint32_t cr3, int user) {
     lock_scheduler();
 
     // default to a new task, but if we find a dead one, re use it
+    int reuse = 0;
     process_t* process = &process_table[total_processes];
     uint32_t pid = total_processes;
     for (uint32_t i = 0; i < total_processes; i++) {
         if (process_table[i].state == STATE_DEAD) {
             process = &process_table[i];
             pid = i;
+            reuse = 1;
         }
     }
 
@@ -116,22 +122,26 @@ int create_task(uint32_t entry_point, uint32_t cr3, int user) {
     process->cr3 = cr3;
     process->state = STATE_READY;
     process->sleep = 0;
+    process->flags = user ? PROCESS_FLAG_USER : PROCESS_FLAG_KERNEL;
 
-    void* stack_bottom = kalloc(4096);
-    uint32_t* esp = (uint32_t*)((uint32_t)stack_bottom + 4096);
-    process->esp0 = (uint32_t)esp;
+    void* kstack_bottom = kalloc(PAGE_SIZE);
+    uint32_t kstack_top = (uint32_t)kstack_bottom + PAGE_SIZE;
+    process->kstack_top = kstack_top;
 
+    uint32_t* esp = (uint32_t*)kstack_top;
     if (user) {
         *(--esp) = 0x23;            // User Data Segment (SS) with RPL 3 (0x20 | 3)
-        *(--esp) = 0xBFFFF000;      // User Stack Pointer (ESP) - location mapped in user space
+        *(--esp) = u_esp;      // User Stack Pointer (ESP) - location mapped in user space
         *(--esp) = 0x0202;          // EFLAGS (Interrupts enabled)
         *(--esp) = 0x1B;            // User Code Segment (CS) with RPL 3 (0x18 | 3)
         *(--esp) = entry_point;     // EIP
+        *(--esp) = 0x23;
     } else {
         // IRET values for Ring 0
         *(--esp) = 0x0202;          // EFLAGS
         *(--esp) = 0x08;            // Kernel Code Segment (CS)
         *(--esp) = entry_point;     // EIP
+        *(--esp) = 0x10;
     }
 
     *(--esp) = 0;             // EAX
@@ -144,7 +154,9 @@ int create_task(uint32_t entry_point, uint32_t cr3, int user) {
     *(--esp) = 0;             // EDI
 
     process->esp = (uint32_t)esp;
-    total_processes++;
+    if (!reuse) {
+        total_processes++;
+    }
     unlock_scheduler();
     return 1;
 }
diff --git a/kernel/scheduler.h b/kernel/scheduler.h
index 20616d0..63755fe 100644
--- a/kernel/scheduler.h
+++ b/kernel/scheduler.h
@@ -6,7 +6,7 @@
 
 void init_scheduler();
 
-int create_task(uint32_t entry_point, uint32_t cr3, int user);
+int create_task(uint32_t entry_point, uint32_t cr3, int user, uint32_t u_esp);
 process_t* current_task();
 
 void sleep(uint32_t ms);
diff --git a/kernel/syscall.S b/kernel/syscall.S
index 931e612..bd7e539 100644
--- a/kernel/syscall.S
+++ b/kernel/syscall.S
@@ -4,33 +4,33 @@
 syscall_handler: 
     cli
 
-    push $0
-    push $0x80
+    pushfl          
+    pushl %cs
 
-    pusha
+    movl 8(%esp), %eax      
+    pushl %eax
+    movl 4(%esp), %ebx      # Get CS
+    movl %ebx, 8(%esp)      # Move CS over Old EIP
+    movl 0(%esp), %ebx      # Get Return EIP
+    movl %ebx, 4(%esp)      # Move Return EIP over CS
+    addl $4, %esp           # Adjust stack pointer
 
-    push %ds
-    push %es
-    push %fs
-    push %gs
+    movw %ds, %ax
+    pushl %eax
 
-    mov $0x10, %ax               
-    mov %ax, %ds
-    mov %ax, %es
-    mov %ax, %fs
-    mov %ax, %gs
+    pushal
+
+    pushl %esp
+    call switch_context
+    movl %eax, %esp
+
+    popal
     
-    push %esp
-    call syscall
-    add $4, %esp
-    
-    mov 28(%esp), %eax
+    popl %eax
+    movw %ax, %ds
+    movw %ax, %es
+    movw %ax, %fs
+    movw %ax, %gs
 
-    pop %gs
-    pop %fs
-    pop %es
-    pop %ds
-
-    popa
-    add $8, %esp
+    sti
     iret
\ No newline at end of file
diff --git a/kernel/syscall.c b/kernel/syscall.c
index 84c5571..c3fb359 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -7,6 +7,8 @@
 
 #include <drivers/vga/vga.h>
 
+#include <lib/print.h>
+
 typedef struct registers {
     uint32_t gs, fs, es, ds;                           // Pushed manually
     uint32_t edi, esi, ebp, esp, ebx, edx, ecx, eax;   // Pushed by pusha
@@ -16,7 +18,7 @@ typedef struct registers {
 
 
 static int32_t sys_exit(int status) {
-    exit();
+    asm volatile("hlt");
     return 0;
 }
 
diff --git a/programs/crt0.S b/programs/crt0.S
index 5521689..655f862 100644
--- a/programs/crt0.S
+++ b/programs/crt0.S
@@ -1,24 +1,21 @@
 .global _start
-.intel_syntax noprefix
 
 .section .text
 _start:
-    xor ebp, ebp
-    push ebp
-    mov ebp, esp
+    xor %ebp, %ebp
+    push %ebp
+    mov %esp, %ebp
 
-    mov eax, [esp + 4]
-    lea ebx, [esp + 8]
-    lea ecx, [esp + 12]
+    mov (%esp), %eax
+    lea 4(%esp), %ebx
+    lea 8(%esp, %eax, 4), %ecx
 
-    push ecx
-    push ebx
-    push eax
+    push %ecx
+    push %ebx
+    push %eax
 
     call main
 
-    push eax
+    push %eax
     call exit
-
-1:  hlt
-    jmp 1b
\ No newline at end of file
+1: jmp 1b   
diff --git a/programs/crt0.s b/programs/crt0.s
deleted file mode 100644
index 8c72caa..0000000
--- a/programs/crt0.s
+++ /dev/null
@@ -1,28 +0,0 @@
-# 0 "crt0.S"
-# 0 "<built-in>"
-# 0 "<command-line>"
-# 1 "crt0.S"
-.global _start
-.intel_syntax noprefix
-
-.section .text
-_start:
-    xor ebp, ebp
-    push ebp
-    mov ebp, esp
-
-    mov eax, [esp + 4]
-    lea ebx, [esp + 8]
-    lea ecx, [esp + 12]
-
-    push ecx
-    push ebx
-    push eax
-
-    call main
-
-    push eax
-    call exit
-
-1: hlt
-    jmp 1b
diff --git a/programs/main.c b/programs/main.c
index 69d8084..a3d10c6 100644
--- a/programs/main.c
+++ b/programs/main.c
@@ -1,8 +1,6 @@
 #include <stdio.h>
-#include <stdlib.h>
 
-int main(int argc, char** argv) {
-    printf("Hello, World from RockOS!\n");
-    
+int main() {
+    printf("RockOS booting...\n");
     return 0;
 }
\ No newline at end of file
diff --git a/programs/makefile b/programs/makefile
index 9d074de..8bf6c96 100644
--- a/programs/makefile
+++ b/programs/makefile
@@ -8,8 +8,8 @@ TARGET = origin.elf
 
 all: $(TARGET)
 
-crt0.o: crt0.s
-	$(CC) $(CFLAGS) -c crt0.s -o crt0.o
+crt0.o: crt0.S
+	$(CC) $(CFLAGS) -c crt0.S -o crt0.o
 
 main.o: main.c
 	$(CC) $(CFLAGS) -c main.c -o main.o
diff --git a/rocklibc/src/rockos/syscall.c b/rocklibc/src/rockos/syscall.c
index fa1b822..f318af0 100644
--- a/rocklibc/src/rockos/syscall.c
+++ b/rocklibc/src/rockos/syscall.c
@@ -1,5 +1,6 @@
 #include <stdint.h>
 #include <stddef.h>
+#include <stdio.h>
 
 typedef int _PDCLIB_fd_t;
 
@@ -14,13 +15,8 @@ static inline int32_t inline_syscall(uint32_t num, uint32_t arg1, uint32_t arg2,
     return ret;
 }
 
-void _exit(int status) {
-    inline_syscall(1, (uint32_t)status, 0, 0);
-    while(1) { asm volatile("hlt"); }
-}
-
 void _PDCLIB_exit(int status) {
-    _exit(status);
+    inline_syscall(1, (uint32_t)status, 0, 0);;
 }
 
 int _PDCLIB_read(_PDCLIB_fd_t fd, void *buf, size_t count) {
@@ -111,4 +107,8 @@ void * sbrk(intptr_t increment) {
     }
 
     return (void *)-1;
+}
+
+void exit(int status) {
+    _PDCLIB_exit(status);
 }
\ No newline at end of file