tasking: fix ELF file execution

grubshit/aaa.asm

@@ -0,0 +1,15 @@
+section .text
+    global _start       ;must be declared for using gcc
+_start:                     ;tell linker entry point
+    mov edx, len    ;message length
+    mov ecx, msg    ;message to write
+    mov ebx, 1      ;file descriptor (stdout)
+    mov eax, 4      ;system call number (sys_write)
+    int 0x80        ;call kernel
+    mov eax, 1      ;system call number (sys_exit)
+    int 0x80        ;call kernel
+
+section .data
+
+msg db  'Hello, world!',0xa ;our dear string
+len equ $ - msg         ;length of our dear string

include/task.h

@@ -60,7 +60,7 @@ typedef struct Process
     struct Process* next;      // Следующий процесс
 } Process;
 
-Process* task_create(uint32_t func, void** args, uint32_t arg_count, uint32_t ring, uint32_t* pagedir);
+Process* task_create(uint32_t func, uint32_t user_esp, uint32_t ring, uint32_t* pagedir);
 void     scheduler_init();
 void     schedule();
 void     scheduler_lock();

src/tasking/exec_from_file.c

@@ -8,6 +8,10 @@
 
 #define DivRoundUp(number, divisor) ((number + divisor - 1) / divisor)
 
+#define USER_STACK_TOP            0xBFFFFFF0//0xC0000000 // Top of user space memory
+#define USER_STACK_SIZE         0x4000         // 16KB stack (4 pages)
+#define USER_STACK_BOTTOM     (USER_STACK_TOP - USER_STACK_SIZE)
+
 disk_ops_t ops1 =
 {
 	.read = ata_read,
@@ -64,7 +68,7 @@ void exec_from_file(const char* filename)
 
     uint8_t* file;
 
-    int result = read_file("/ebalo/testfile", &file);
+    int result = read_file("/ebalo/aaa", &file);
     printf("result: %X\n", result);
     printf("buffer: %s\n", file);
 
@@ -95,7 +99,8 @@ void exec_from_file(const char* filename)
             printf("not PT_LOAD, skipping...\n");
             continue;
         }
-      int pages_needed = (elf_phdr->p_memsz / 0x1000) + 1;
+
+        int pages_needed = DivRoundUp(elf_phdr->p_memsz, 0x1000);//(elf_phdr->p_memsz / 0x1000) + 1;
         printf("pages needed: %X\n", pages_needed);
 
         for(int j = 0; j < pages_needed; j++)
@@ -104,29 +109,55 @@ void exec_from_file(const char* filename)
             void* phys_addr = alloc_page();
 
             printf("mapping 0x%X -> 0x%X\n", phys_addr, vaddr);
-        //map_page_in_directory(proc_pd, phys_addr, (void*)vaddr, PAGE_PRESENT | PAGE_RW | PAGE_USER);
             map_page(phys_addr, (void*)vaddr, PAGE_PRESENT | PAGE_RW | PAGE_USER);
         }
 
-      
-
         memcpy((void*)elf_phdr->p_vaddr, file+elf_phdr->p_offset, elf_phdr->p_filesz);
         
-      
+        if (elf_phdr->p_memsz > elf_phdr->p_filesz) {
-
+            uint32_t bss_start = elf_phdr->p_vaddr + elf_phdr->p_filesz;
-      uint32_t file_start = (elf_phdr->p_vaddr & ~0xFFF) + elf_phdr->p_filesz;
+            uint32_t bss_end = elf_phdr->p_vaddr + elf_phdr->p_memsz;
-      uint32_t file_end = (elf_phdr->p_vaddr & ~0xFFF) + pages_needed * 0x1000;
+            memset((void*)bss_start, 0, bss_end - bss_start);
-      memset((void*)file_start, 0, file_end - file_start);
+        }
 
         printf("p_filesz: 0x%X (%X)\n", elf_phdr->p_filesz, elf_phdr->p_filesz);
-      
-      
-
         printf("================================\n\n\n\n");
     }
     
+    printf("setting up the user stack...\n");
+
+    //TODO: i think this thing allocates more pages than needed
+    for (uint32_t vaddr = USER_STACK_BOTTOM; vaddr <= USER_STACK_TOP; vaddr += PAGE_SIZE) {
+        void* phys_addr = alloc_page();
+        if(!phys_addr)
+        {
+            printf("error allocating user stack page, aborting...\n");
             set_page_dir(curr_pd_phys);
-  Process* p_task1 = task_create(elf_ehdr->e_entry, NULL, 0, 3, proc_pd);
+            //TODO: free previously allocated pages
+            return;
+        }
+        map_page(phys_addr, (void*)(vaddr & ~0xFFF), PAGE_PRESENT | PAGE_RW | PAGE_USER);
+        printf("mapping stack 0x%X -> 0x%X (0x%X)\n", (uint32_t)phys_addr, vaddr, (vaddr & ~0xFFF));
+        memset((void*)(vaddr & ~0xFFF), 0, PAGE_SIZE); // Add this
+    }
+    /*
+    uint32_t user_esp = USER_STACK_TOP;
+
+    // envp (environment pointer array) = NULL terminator
+    user_esp -= 4; 
+    *(uint32_t*)user_esp = 0;
+
+    // argv (argument pointer array) = NULL terminator
+    user_esp -= 4;
+    *(uint32_t*)user_esp = 0;
+
+    // argc (argument count) = 0
+    user_esp -= 4;
+    *(uint32_t*)user_esp = 0;
+    */
+    
+    set_page_dir(curr_pd_phys);
+    Process* p_task1 = task_create(elf_ehdr->e_entry, USER_STACK_TOP, 3, proc_pd);
     
     asm volatile("sti");
 }

src/tasking/sys_exit.asm

@@ -16,10 +16,27 @@ sys_exit_handler:
     mov fs, ax
     mov gs, ax
 
+    mov eax, [esp+44]       ; System call number
+    mov ebx, [esp+32]       ; Arg1
+    mov ecx, [esp+40]       ; Arg2
+    mov edx, [esp+36]       ; Arg3
+    mov esi, [esp+28]       ; Arg4
+    mov edi, [esp+24]       ; Arg5
+
+    ; Print debug information
+    push edi                ; arg5
+    push esi                ; arg4
+    push edx                ; arg3
+    push ecx                ; arg2
+    push ebx                ; arg1
+    push eax                ; syscall number
+    push syscall_debug_fmt
+
     ; Выполняем действие
-    push sys_exit_msg
+    ;push sys_exit_msg
     call printf
-    add esp, 4
+    ;add esp, 4
+    add esp, 28
 
     ; Восстанавливаем сегменты Ring 3
     pop gs
@@ -47,3 +64,4 @@ heh:
 
 section .data
 sys_exit_msg: db "Returned from Ring 3", 0
+syscall_debug_fmt: db "Syscall #%x, args: 0x%x 0x%x 0x%x 0x%x 0x%x", 10, 0

src/tasking/task.c

@@ -22,7 +22,7 @@ extern Process* current;
 extern uint32_t pid_counter;
 extern uint32_t task_count;
 
-Process* task_create(uint32_t func, void** args, uint32_t arg_count, uint32_t ring, uint32_t* pagedir)
+Process* task_create(uint32_t func, uint32_t user_esp, uint32_t ring, uint32_t* pagedir)
 {
     void *p_physical = alloc_page();
     Process* p = (Process*)((uint32_t)p_physical+0xC0000000);
@@ -60,14 +60,15 @@ Process* task_create(uint32_t func, void** args, uint32_t arg_count, uint32_t ri
 
     if(ring == 3)
     {
-        void* user_stack_physical = alloc_page();
+        /*void* user_stack_physical = alloc_page();
 
         uint32_t user_stack_virtual_top = 0xBFFFF000 - ((p->pid -1) * (USTACKSIZE + 4096)); // Уникальный верх стека для каждого процесса
         uint32_t user_stack_virtual_base = user_stack_virtual_top - USTACKSIZE;
 
         map_page_in_directory(p->pagedir, user_stack_physical, (void*)user_stack_virtual_base, PAGE_PRESENT | PAGE_RW | PAGE_USER); // Флаги 0x7
+        */
 
-        p->tf->usermode_esp = user_stack_virtual_top;
+        p->tf->usermode_esp = user_esp;//user_stack_virtual_top;
 
     }
 
@@ -145,7 +146,7 @@ void scheduler_init()
 {
     uint32_t* kernel_tasks_pagedir = (uint32_t*)create_page_dir();
 
-    task_create((uint32_t)idle, NULL, 0, 0, kernel_tasks_pagedir);
+    task_create((uint32_t)idle, 0, 0, kernel_tasks_pagedir);
 
     /*void* args1[] = {(void*)42, (void*)"ebalo"};
     task_create((uint32_t)task1, args1, 2, 0, kernel_tasks_pagedir);
@@ -195,7 +196,7 @@ void jump_usermode2(void) {
 
     uint32_t* proc_pd = create_page_dir();
     uint32_t* proc2_pd = create_page_dir();
-    Process* p_task1 = task_create(0x400000, NULL, 0, 3, proc_pd);
+    /*Process* p_task1 = task_create(0x400000, NULL, 3, proc_pd);
     Process* p_task2 = task_create(0x400000, NULL, 0, 3, proc2_pd);
 
     if (map_page_in_directory(p_task1->pagedir, 
@@ -216,6 +217,6 @@ void jump_usermode2(void) {
         printf("jump_usermode2: Failed to map user code into task's PD for PID %d\n", p_task2->pid);
         // TODO: Terminate/cleanup p_task1, free code_phys_task1
         return;
-    }
+    }*/
     scheduler_unlock();
 }